Handbook of Biodiversity Methods

This page intentionally left blank Handbook of Biodiversity Methods

Biodiversity is recognised to be of global (lower plants, fungi, vascular plants, importance, yet species and habitats continue to be invertebrates, fish, amphibians, reptiles, birds under increasing pressure from human-induced and mammals). influences, whether in urban, rural or wilderness The Handbook provides an invaluable settings. Environmental concerns have never compendium for ecologists, wildlife managers, before been so high on the political agenda, driving nature conservation professionals, local and increased legislation which places major emphasis national authorities, environmental managers, on individual, public and corporate responsibility corporate bodies and companies, government for conserving biodiversity and for managing conservation agencies and regulators involved in development in an environmentally sensitive and auditing ecological resources. It will enable sustainable way. The starting point for assessing practitioners to better monitor the condition of the legal compliance is the requirement for a biodiversity resource, resulting in improved data comprehensive biodiversity audit. For those upon which to base future conservation, needing to undertake such audits, this Handbook management, development and policy decisions provides standard procedures for planning and and actions. conducting a survey of any terrestrial or freshwater David Hill is Director of Ecology for RPS Group species or habitat and for evaluating the data so as plc, a leading environmental consultancy. to determine its local, national and international Matthew Fasham is a Principal Consultant for significance. RPS Group plc. Organised in three parts, the Handbook first Graham Tucker is a freelance ecologist with addresses planning, providing a pragmatic Ecological Solutions. approach to method selection, sampling strategy, Michael Shewry is an environmental statistician and data analysis and evaluation. The second part with Scottish Natural Heritage. is devoted to habitats, describing survey, Philip Shaw is an environmental audit specialist evaluation and monitoring methods for a broad with the Advisory Services of Scottish Natural ra nge o f hab itats.III c onsPart iders spe cies andHeritage. provides information on general methods before Any opinions expressed are those of the authors addressing specific methods of survey and and do not necessarily represent the views of RPS mo nito rin g fo r t he majo r t axon omicor Scottish g ro Natural ups Heritage.

Handbook of Biodiversity Methods Survey, Evaluation and Monitoring

Edited by David Hill Matthew Fasham Graham Tucker Michael Shewry Philip Shaw    Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo

Cambridge University Press The Edinburgh Building, Cambridge  ,UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridg e.org /9780521823685

This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.

First published in print format 2005

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Cambridge University Press has no responsibility for the persistence or accuracy of s for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. In memory of Colin J. Bibby, an outstanding conservation scientist

Contents

Preface page xi Part II Habitats Acknowledgements xiii GRAHAM TUCKER, MATTHEW FASHAM, TIM RICH, MICK REBANE, GEORGE PETERKEN, FIONA Part I Planning MCMEECHAN AND DICK BIRNIE GRAHAM TUCKER, MATTHEW FASHAM, DAVID HILL, 4 Introduction to habitat evaluation 105 MICHAEL SHEWRY, PHILIP SHAW AND MAX WADE G. TUCKER, AND M. FASHAM 1 Introduction to planning 4.1 How to use the Handbook: a recap 105 G. TUCKER, D. HILL AND M. FASHAM 4.2 Habitat survey and monitoring 105 1.1 The purpose of surveying and monitoring 3 5 Habitat requirements and issues 107 T. RICH, G. PETERKEN, G. TUCKER, F. MCMEECHAN 2 Planning a programme 6 AND D. DOBSON G. TUCKER, M. FASHAM, D. HILL, M. SHEWRY, P. SHAW AND M. WADE 5.1 Woodland and scrub 107 5.2 Lowland wood-pastures and parkland 114 2.1 Setting the objectives for the monitoring 5.3 Farmland boundary features 117 programme 6 5.4 Grassland and herbaceous communities 121 2.2 Selection of methods for monitoring 5.5 Limestone pavement 124 each attribute 17 5.6 Lowland and upland 2.3 Designing a sampling strategy 23 heathland 126 2.4 Reviewing the monitoring programme 42 5.7 Fens, carr, marsh, swamp and reedbed 128 2.5 Data recording and storage 46 5.8 Lowland raised bog 130 2.6 Data analysis, interpretation and review 49 5.9 Standing open water 132 3 Biodiversity evaluation methods 65 5.10 Rivers and streams 136 G. TUCKER 5.11 Montane habitats 141 3.1 Biodiversity values and evaluation 5.12 Blanket bog 143 purposes 65 5.13 Maritime boulders, rocks, cliffs and 3.2 A framework for ecological evaluations 65 slopes 145 3.3 Identification of valuable ecosystem 5.14 Shingle above high tide 147 components 65 5.15 Sand dunes and strandline vegetation 148 3.4 Principles underlying the setting of 5.16 Saltmarsh 150 conservation priorities 68 6 Methods for surveying habitats 154 3.5 Species and habitat conservation priority lists 72 6.1 General habitat survey and monitoring 3.6 Site evaluations and selection of methods 154 protected areas 81 R.V. BIRNIE, G. TUCKER AND M. FASHAM 3.7 Site conservation designations 88 6.2 Physical attributes 195 3.8 Site evaluations for management M. FASHAM AND G. TUCKER planning 95 6.3 River morphology and aquatic 3.9 Site evaluations for Environmental vegetation composition 197 Impact Assessments (EIAs) 96 G. TUCKER

vii viii CONTENTS

6.4 Ground and shrub vegetation 201 12 Lichens 279 T. RICH, M. REBANE, M. FASHAM, F. MCMEECHAN S. DAVEY, M. FASHAM AND D. DOBSON AND D. DOBSON 12.1 Attributes for assessing condition 280 6.5 Trees and woodland stands 222 12.2 General methods 280 G. PETERKEN AND M. FASHAM 12.3 Lichen conservation evaluation criteria 284

7 Surveying and monitoring management or 13 Bryophytes 288 environmental impacts 237 G. ROTHERO, D. DOBSON AND M. FASHAM M. REBANE, M. FASHAM AND G. TUCKER 13.1 Attributes for assessing condition 288 7.1 Grazing and browsing 237 13.2 General methods 289 7.2 Burning 240 13.3 Bryophyte conservation evaluation 7.3 Erosion 243 criteria 292 7.4 Vegetation surveys in relation to 14 Aquatic macrophytes and algae 295 developments 244 N. STEWART AND M. WADE

8 Habitat conservation evaluation criteria 245 14.1 Attributes for assessing condition 296 G. TUCKER AND F. MCMEECHAN 14.2 General methods 296 8.1 Key evaluation considerations 245 14.3 Requirements for species of particular 8.2 Protection status in the UK and EU 245 conservation importance 300 8.3 Conservation status in the UK 246 14.4 Aquatic macrophyte conservation evaluation criteria 301

Part III Species 15 Vascular plants 303 9 Introduction to species assessment 253 T. RICH, V. HACK AND F. MCMEECHAN

9.1 Species surveying and monitoring 253 15.1 Attributes for assessing condition 305 15.2 General methods 307 10 General principles and methods for species 255 15.3 Vascular plant conservation M. FASHAM AND S. MUSTOE evaluation criteria 318 10.1 Introduction 255 16 Dragonflies and damselflies 322 10.2 Terminology 255 C. PLANT, R. SANDS AND M. FASHAM 10.3 Total counts 257 10.4 Timed searches 257 16.1 Attributes for assessing condition 322 10.5 Quadrats 258 16.2 General methods 322 10.6 Distance sampling 260 16.3 Odonata conservation evaluation 10.7 Line and strip transects 264 criteria 327 10.8 Point counts 266 17 Butterflies 328 10.9 Trapping webs 267 C. PLANT, R. SANDS AND M. FASHAM 10.10 Removal method 268 17.1 Attributes for assessing condition 328 10.11 Mark–recapture techniques 268 17.2 General methods 329 11 Fungi 271 17.3 Butterfly conservation evaluation R. WATLING, M. FASHAM AND D. DOBSON criteria 333

11.1 Attributes for assessing condition 272 18 Moths 335 11.2 General methods 272 C. PLANT, R. SANDS AND M. FASHAM 11.3 Fungus conservation evaluation 18.1 Attributes for assessing condition 335 criteria 276 18.2 General methods 336 Contents ix

18.3 Macromoth conservation evaluation 24.6 Protection status in the UK and EU 427 criteria 339 25 Bats 433 19 Other terrestrial invertebrates 341 R. STEBBINGS, H. MANSFIELD AND M. FASHAM P. DENNIS, C. PLANT, R. SANDS AND M. FASHAM 25.1 Attributes for assessing condition 433 19.1 Attributes for assessing condition 342 25.2 General methods 438 19.2 General methods 342 25.3 Bat conservation evaluation criteria 446 19.3 Terrestrial invertebrate conservation 26 Other mammals 450 evaluation criteria 357 A. BENNETT, P. RATCLIFFE, E. JONES, H. MANSFIELD 20 Aquatic invertebrates 359 AND R. SANDS P. KERRISON, T. NORMAN AND M. FASHAM 26.1 Attributes for assessing condition 450 20.1 Attributes for assessing condition 359 26.2 Indirect methods 450 20.2 General methods 360 26.3 General methods 455 20.3 Requirements for species of particular 26.4 Direct methods 460 conservation importance 365 26.5 Requirements for species of particular 20.4 Aquatic invertebrate conservation conservation importance 464 evaluation criteria 365 26.6 Mammal conservation evaluation criteria 469 21 Fish 368 N. GILES, R. SANDS AND M. FASHAM Appendix 1 Monitoring and reporting obligations 21.1 Attributes for assessing condition 368 under international conservation agreements 473 21.2 General methods 375 Appendix 2 Relationship between BAP Priority 21.3 Freshwater fish conservation Habitat and Broad Habitat categories and Habitats evaluation criteria 385 Directive nomenclature 478 22 Amphibians 387 Appendix 3 Annotated list of key references for plant D. LATHAM, E. JONES AND M. FASHAM identification 490 22.1 Attributes for assessing condition 387 Lichens 490 22.2 General methods 388 Bryophytes 490 22.3 Amphibian conservation evaluation Charophytes 491 criteria 401 Ferns 491 23 Reptiles 404 Vascular plants 491 D. LATHAM, E. JONES AND M. FASHAM Appendix 4 Determining appropriate quadrat size for 23.1 Attributes for assessing condition 404 vegetation sampling 493 23.2 General methods 404 23.3 Reptile conservation evaluation criteria 410 Appendix 5 The relocation of permanent plots 495

24 Birds 412 Mapping 495 S. MUSTOE, D. HILL, D. FROST AND G. TUCKER Marker posts 495 Paint 495 24.1 Attributes for assessing condition 412 Buried metal markers 495 24.2 General methods 413 Photographs 495 24.3 Some specific methods used in Total Stations 496 specialist EIA studies 418 Global positioning systems (GPS) 496 24.4 Some key species regularly considered in EIA studies 420 Appendix 6 Equipment required for undertaking 24.5 Bird conservation evaluation criteria 422 different types of survey 497 x CONTENTS

Recommended sources of further information 519 Aquatic invertebrates (Chap2ter0) 524 Fish (Chapter2 1) 524 Habitat requirements (Chapter5) 519 Amphibians (Chapter2 2) 525 Survey methods (Chapter6) 519 Reptiles (Chapter2 3) 526 Methods for species assessment (Chapter10) 519 Birds (Chapter2 4) 526 Fungi (Chapter1 1) 520 Bats (Chapter2 5) 529 Lichens (Chapter1 2) 520 Other mammals (Chapter26) 529 Bryophytes (Chapter1 3) 521 Aquatic macrophytes and algae (Chapter14) 521 References 530 Vascular plants (Chapter15) 522 Glossary 551 Dragonflies and damselflies (Chapter16) 522 Monitoring terms and acronyms 551 Butterflies (Chapter1 7) 523 Statistical terms 552 Moths (Chapter1 8) 523 Other terrestrial invertebrates (Chapter19) 523 Index 556 Preface

This generation is living at a time when the world’s to expand their reserve network and extend new biodiversity resources have never been so impover- habitats near existing ones by means of novel tech- ished. If we take the UK as an example of what has niques based on scientific understanding. There is happened across many parts of the planet, since large-scale restoration of contaminated land sites. 1945, largely as a result of agricultural intensifica- Coastal managed realignment offers opportunities tion, we have lost over 50% of our ancient lowland to create massive areas of wet grassland, saltmarsh woodlands, 150 000 miles of hedgerow, 95% of and reedbed habitat, which will provide substan- traditional hay meadows, 80% of chalk downland tial benefits to wildfowl and waders. Industry, too, and 80% of wetland fens and mires. This has given is working with organisations to create large-scale rise to massive losses in some, once very common, reserves in currently uninteresting farmland, a farmland birds: in the past 30 years 40% of Song prime example being the Great Fenland Project in Thrushes, 54% of Yellowhammers, a staggering the Cambridgeshire Fens of the UK. 87% of Starlings and 90% of Corn Buntings have As biodiversity has dwindled in the past 50 years, disappeared. so policies and laws aimed at turning the tide have In addition to agricultural intensification, devel- flourished. There are now over 200 legal instruments opment pressure as a result of industrialisation, aimed at protecting the environment and which human population expansion and resultant have an impact on countries such as the UK. The increases in the ‘ecological footprint’ of our own greatest successes have been achieved where there species through, for example, house building, air- has been government regulation: we now have the ports, seaports, road infrastructure, water supply, best air and water quality in Britain for about 200 energy generation, waste management, freight years, almost entirely as a result of regulation. Key distribution and extraction of raw materials, has instruments for biodiversity conservation in the UK taken its toll on biodiversity. The UK government’s are the Wildlife & Countryside Act, the Countryside sustainable development commission recently and Rights of Way Act, The Nature Conservation announced that the country has a very long way to (Scotland) Act EU Birds and Habitats Directives, go before existing developments, and the way we the Habitats Regulations, the EIA Directive and manage environmental resources, can be deemed to EIA Regulations, the Hedgerow Regulations, Bonn be ‘sustainable’. This is without any consideration of Convention, Ramsar Convention, Bern Convention, the impending threat from climate change. European and National Red Lists of species of con- But it would be wrong to focus entirely on the servation concern, and Biodiversity Action Plans. negatives. There are signs that our attitudes to our A whole industry has developed to support biodiver- environment are changing and there are a growing sity conservation, to save what we have and improve number of examples where the primary focus upon it. In parallel there has been increased site- of governments, companies and individuals is based protection: the designation of local wildlife towards the stitching back of the fabric of the sites, green corridors, County Wildlife Sites, Sites of environment and countryside. A range of agri- Special Scientific Interest, National Nature Reserves, environment schemes is attempting to redress the Special Protection Areas, Special Areas of damage caused to farmland biodiversity by the Conservation, Biosphere Reserves and World Common Agricultural Policy, reforming subsidies Heritage Sites. away from production and into environmental During this recent period we have moved from a benefits. Organisations such as the RSPB continue natural history mentality to an accountancy

xi xii PREFACE

mentality, where numbers and targets are the order survey and/or monitoring programme, sampling of the day. Government has set out some ambitious strategy and data analysis. There is then a section targets for biodiversity: by 2010, for example, it which describes generically how to evaluate the wants 95% of all SSSIs in England to be in a data collected: what does it mean at different spa- Favourable Condition. We have a long way to go. tial scales? Currently about 42% of the one million or so hec- Part II is devoted to habitat survey, evaluation tares of SSSIs in England fail to make the grade of and monitoring, describing approaches for the full ‘Favourable Condition’. The percentages in range of habitats in the UK but with direct rele- unfavourable condition in England, according to vance to many countries. For each habitat type the selected habitats, are: rivers and streams 69%, upland potential attributes that indicate condition are grasslands and heaths c.65%,fen,marshandswamp defined, together with appropriate and commonly 35%, and lowland broadleaved woodland 33%. This used methods for surveying them and establishing gives an idea of the widespread losses in quality that a monitoring scheme for the habitat concerned. have taken place in addition to losses in habitat Based on structural similarities the methods can quantity. Changes to quality are being addressed by be applied to the full range of habitat types found a plethora of site or conservation management in Europe and, indeed, in other parts of the world. plans, and similar mechanisms are being used to Evaluation criteria are developed and defined for mitigate for development impacts, including Section each habitat. 106 agreements, unilateral undertakings and mitiga- Part III is devoted to the survey, evaluation and tion plans. monitoring of species. General methods applicable So, against this background of biodiversity to a range of taxa are first described, such as total decline and a commitment to rebuild it, there are counts, timed searches, use of quadrats, distance three observations I would make. First, ecology has sampling, line transects, point counts, etc. Each a vital part to play in delivering a better quality taxonomic group is then addressed, from fungi to environment and better quality of life for people. mammals. For each group, the attributes for asses- Second, environmental quality improvements are sing condition are described, followed by survey increasingly being seen as solutions rather than as and monitoring methods that can be applied, and costly problems at the levels of both the corporate then details of particular methods for species of entity and society at large. Third, there is a need for conservation importance as appropriate. Finally, high-quality information on which to base deci- for each group there is a section that describes sions. We have written this Handbook in order to the currently applicable conservation evaluation enable biodiversity data to be collected and evalu- criteria. ated according to standard procedures. Future I hope that the approaches and methods decisions on policy reforms, land management, described in this Handbook will stand the test of development impacts and biodiversity conserva- time and enable us to better monitor the condition tion initiatives at a range of spatial scales can then of the biodiversity resource. We should then be able be based on fact rather than on conjecture. to plan improved biodiversity conservation and The Handbook consists of three parts. The first measure how well we are doing towards meeting (Part I) addresses planning and describes howtargets to in the years ahead. set objectives, what is it you actually want to do, selecting the appropriate method, how to design a David Hill Acknowledgements

The writing of the Handbook has been a mammoth Primrose, Deborah Procter, Geeta Puri, Rob task. However, we have been very fortunate to Raynor, Terry Rowell, Pamela Strachan, Chris have been able to assemble a highly competent Sydes, Neale Taylor, Gavin Tudor, Stephen Ward, team of authors who not only eased the task but Christine Welch, Peter Wortham and the late were able to take the text to greater depths of David Phillips. detail than any one of the editors could possibly RPS provided time and logistical support to the have achieved. Their wisdom, knowledge and whole project which enabled us to meet deadlines experience shines through. We therefore thank and to see the whole project through to a fruitful our contributing authors for their superb support conclusion. We are most grateful to them. Alan and hard work. Crowden of Cambridge University Press and We were also fortunate to have had to hand a Michael Usher, then Chief Scientist for Scottish long list of experts who kindly commented on the Natural Heritage, were convinced that the project original version. Our sincere thanks go to Helen was worthwhile and gave much encouragement Armstrong, Sally Blyth, Phil Boon, Mairi Cole, and support. Andrew Coupar, Louise Cox, Andy Douse, Kathy Finally, we thank the many professionals who Duncan, Willie Duncan, Lynne Farrell, Vin are striving to ensure we stitch back together the Fleming, Stuart Gardner, Martin Gaywood, Doug fabric of the countryside, both in the UK and Gilbert, Dave Horsfield, Keith Kirby, John Kupiec, abroad, to secure a future environment in which Kate Holl, Philip Immirzi, Ross Johnstone, Ed it is worth living. We hope this book plays some Mackey, Jane Mackintosh, Jill Matthews, Angus small part in assessing how well we are doing in the MacDonald, Ed Mountford, John Orr, Brigid years to come.

xiii

Part I * Planning

1 * Introduction to planning

1.1 THE PURPOSE OF SURVEYING AND evaluated against set agreed criteria. Impacts are MONITORING considered in respect of this resource and assessed for significance. Parts II and III of this Handbook The development of a successful programme is describe specific survey methods for habitats and dependent upon being clear about what you the full range of species from lower plants to mam- want to do and why, i.e. your objectives. It is there- mals. However, for some studies, particularly fore important to define what monitoring is and in relation to testing the effects of macro- how surveys relate to monitoring. Survey and environmental policy changes at a large spatial monitoring is undertaken for a wide range of scale, actual monitoring is performed. The empha- objectives: for example, to measure a site’s qual- sis in Part I of this Handbook is the design of data ity, or a species’ abundance, to assess species collection and the analytical treatment of the data and habitat trends, for Environmental Impact collected. Much of Part I therefore considers the Assessment (EIA) studies, for corporate reporting, planning, design and implementation of survey or to assess compliance with international conser- and monitoring, the latter often comprising a vation agreements. These operate at many differ- series of replicated surveys using standard ent spatial scales and therefore necessitate methods. targeted methods for different applications, objec- Once the data have been collected they will need tives and deliverables. The significance and global to be used for a specific purpose. One of the most importance of monitoring nature conservation is important uses is to evaluate a site, species, com- aptly summarised in Appendix 1, which describes munity, habitat, region, etc. Part I therefore the monitoring and reporting obligations under includes a section on generic approaches to evalua- international conservationagreementsasan tion of biodiversity data, with more specific treat- example of the far-reaching implications of the ment for habitats and species given in the relevant need to use adequate methods. sections of Parts II and III. As with monitoring, it is essential at the outset 1.1.1 General objectives of surveying and of a survey to define objectives. A project may not monitoring meet its full potential unless the aims are properly understood and researched before data collection For the purposes of Environmental Impact begins. Before planning your survey methods, con- Assessment (EIA) studies, the term ‘survey’ defines sider the variety of possible scenarios that could the collection of spatial and/or temporal data about dictate your project’s fieldwork techniques. Do a species, a community or a habitat. The informa- the results need to apply to one site or to a wide tion provides a snapshot of presence, absence and, geographical area? Are many species involved dependent on its design and sophistication, abund- or just one? Are accurate counts needed (spatially ance and spatial distribution. In EIA studies the referenced) or will relative counts or presence– survey data are used to evaluate the ecological absence data suffice? Answers to these questions resource on a site, which is then assessed or will determine the time commitments required

# RPS Group plc and Scottish Natural Heritage 2005. 4 1 INTRODUCTION TO PLANNING

and hence cost. In general terms, surveys coshouldnducte dnot attempt to describe the general ecology for EIA studies should aim to provide informationof a site. Unfortunately, monitoring schemes often on the following. resort to measuring a wide variety of variables, which may or may not be related to the questions * What species and habitats ¼occur the resource)?( that need to be addressed. As a result, resources * Where do they occur? may be spent collecting unnecessary data. Even * How many of them are there or how much of the worse, it may be found that key questions cannot habitat is there? be answered with the information obtained. This is * How does this amount of the resource relate to because monitoring is often planned backwards, that existing in the wider area/biogeographical on a ‘collect-now (data), think-later (of a useful region? question)’ basis (Roberts,1991 ). * What are the seasonal changes and when is the Strictly speaking, the minimum requirement of most susceptible or sensitive period for these spe- monitoring is an assessment of adherence to, or cies/habitats? deviation from, formulated standards. However, it Monitoring is often loosely regarded as isa clearlypro- desirable to collect data in such a way gramme of repeated surveys in which qualitativethat gradual change can be detected to assist man- or quantitative observations are made, usuallyagement by decision-making. Management adjust- means of a standardised procedure. However,ments by (at both field and policy level) require itself this is merely surveillance as there isknowledge no pre- of the dynamic situation, i.e. whether conception of what the findings ought theto featurebe. is moving towards or away from the Monitoring can be more rigorously definedstandard, as from which direction, and whether the ‘intermittent (regular or irregular) surveillancechange is expected, acceptable or otherwise undertaken to determine the extent of compliance(Rowell, 1993). with a predetermined standard or the degreeMonitoring of should not be confused with research deviation from an expected norm’ (Hellawell,aimed at investigating ecological processes. 1991) . In this context, a standard can be Nevertheless,a baseline data collected for monitoring purposes position (e.g. maintenance of the existing areacan sometimesof a also be used to examine possible particular habitat or population of a particularcauses spe- of change and to investigate the relationship cies) or a position set as an objective (e.g.between mainten- features of interest and environmental variance of more than 200 ha of a desired ableshabitat and pressures.or Such information can then be more than 200 individuals of a desired species).used to formulate appropriate responses. For exam- Thus, whereas surveys and surveillance areple, to comparison a of sward composition with stocking large extent open-ended, a monitoring programmedensity may predict optimal management regimes. has a specific purpose that requires the standardFurther monitoringto of the vegetation and stocking be defined or formulated in advance. This ratesrequires can then confirm whether management and the identification of interestfeatures (e.g. various habitat objectives are being met. habitats and species), theirattributes (e.g. area, Thus, in summary, monitoring can: numbers, structure and reproductive success) and their target state, i.e. standardthe that is to be* establish whether standards are being met; monitored (seeGlossary for detailed definitions of* detect change and trigger responses if any of the monitoring terms). Monitoring for conservationchanges are undesirable; purposes should be closely linked to site *manage-contribute to the diagnosis of the causes of ment and should test whether conservation change;and and management objectives have been achieved,* assessas the success of actions taken to maintain outlined in Figure1.1 . standards or to reverse undesirable changes, The monitoring programme and methods cho-and, where necessary, contribute to their sen must befocused and fit for their andpurpose improvement. 1.1 The purpose of surveying and monitoring 5

Figure 1.1. A schematic representation of the relationship between site management and monitoring.

Monitoring should therefore be an integral part of Designated Sites (JNCC, 1997) has been adopted by the all conservation programmes. agencies and the Joint Nature Conservation Committee (JNCC). This formalises the monitoring 1.1.2 Common Standards Monitoring in principles outlined above and provides standards for the UK the setting of objectives, judging the condition of site features, recording activities and management mea- The UK statutory conservation agencies (the sures, and monitoring and reporting within an Countryside Council for Wales, English Nature, the agreed time-frame. Environment and Heritage Service in Northern For further information on the Common Ireland, and Scottish Natural Heritage) have under- Standards approach see Rowell (1993, 1997) and taken to monitor statutory protected sites to deter- Brown (1994). See Shaw & Wind (1997) for a discus- mine whether the features of interest for which each sion of monitoring European conservation sites. site has been designated are being maintained in a Detailed guidance on the interpretation and appli- favourable condition. To provide a basic framework cation of Common Standards Monitoring has been that will ensure consistent monitoring throughout prepared by the statutory agencies and is available the UK, a Statement of Common Standards for Monitoring from them. 2 * Planning a programme

The major steps involved in planning and execut- As there is clearly a link between habitat and ing a monitoring programme are illustrated in species features, there is often likely to be some Figure 2.1. Many of the aspects are relevant to overlap between their monitoring requirements. planning and executing a survey. A list of key con- Species, particularly plants, are often essential com- siderations that must be addressed when planning ponents that define a habitat (e.g. ericoid shrubs on a monitoring programme is given in Box 2.1 with heathlands). Individual species or species assem- the relevant section numbers. All of these issues blages may therefore often be monitored as attri- should be carefully considered in a step-by-step butes of a habitat feature. process before any fieldwork is started. In addition to monitoring species for which sites have been designated, it is important to monitor 2.1 SETTING THE OBJECTIVES FOR THE the area and quality of suitable habitat for such MONITORING PROGRAMME species. There may also be other species that, although not necessarily of conservation concern Clearly and explicitly defining your objectives is in themselves, may require monitoring by virtue probably the most important single step of any of association with a species that is a feature of monitoring programme. Failure to do so may render interest (for example, the food plant of a particular any results gained inappropriate to the question you animal species). Monitoring such habitats and asso- wished to address, and therefore useless. Carefully ciated species can give extra information about the defining your objectives will also allow you to select condition of species features that may prove useful the most appropriate methodology. In particular it for formulating management options for the site. is essential that you ask yourself: What do I really Some sites may be important for the presence need to know? The process of defining objectives of a species assemblage (e.g. a diverse community underpins good site management principles and the of insects or a good example of a particular vegeta- development of management plans (see, for exam- tion community). For these assemblages, it may be ple, CCW, 1996) of which monitoring should be an possible to monitor one or more indicator species, integral part (Figure 1.1). Guidance on establishing which can be used to infer the presence or status clearly defined objectives is provided below. of other associated species, rather than monitoring each individual species. However, the use of indicator species should be approached with care, 2.1.1 What features of conservation andinparticularshouldonlybereliedonwhen interest are to be monitored? the relationship between the condition of the indi- The first step in defining the objectives of any eco- cator and that of the interest feature has been logical monitoring programme must be the identi- proven and quantified. If this is not the case, fication of features of interest on the site. Biological then all relevant species will need to be moni- features may be habitats, species or species tored. See Rowell (1994) for further guidance on assemblages. the use of indicators.

# RPS Group plc and Scottish Natural Heritage 2005. 2.1 Setting objectives 7

Identify the features Citations, Site Management that should be monitored Statements, etc. on the site

Select attributes for Habitats: Part II Chapter 5 each feature Species: Part III Chapters 11–26

Define limits or targets for attribute

Part I Section 2.2 Select methods for Habitats: Part II Chapter 6 monitoring each attribute Species: Part III Chapters 11–26

Repeat for other attributes of the feature

Devise sampling strategy where necessary Part I Section 2.3

Collect data

Analyse data Part I Section 2.6

Determine whether attributes achieve targets set

Once all attributes have been assessed, determine feature condition

Repeat for other features

Act on findings if features not in acceptable condition

Figure 2.1. A schematic diagram of the steps involved in a monitoring programme.

The monitoring of assemblages presents some Assemblages can be assessed by using species rich- problems. On a site important for its diverse beetle ness or diversity indices; judgement will be required community, for example, does the loss of one to decide how to set limits for these. species constitute serious damage, or do several In general, an essential part of monitoring a species need to decline before the assemblage is species of conservation concern will be to monitor considered to be in an unacceptable condition? the area of suitable habitat, and an essential part of 8 2 PLANNING A PROGRAMME

Box 2.1 A checklist of considerations DESIGNING A SAMPLING STRATEGY (2.3) during the preparation of a monitoring Has the method been thoroughly tested and are programme preliminary field trials necessary? (2.3.1) Is the method sufficiently precise? (2.3.2) SETTING OBJECTIVES FOR THE MONITORING Should sample locations be permanent or not? (2.3.3) PROGRAMME (2.1) When should the data be collected? (2.3.6) What features of conservation interest are to be How will consistency be assured? (2.3.7) monitored? (2.1.1) What is the objective for each feature? (2.1.2) REVIEWING THE MONITORING PROGRAMME (2.4) What attributes define condition in these features and Are there sufficient long-term resources available? (2.4.1) what are likely to be their acceptable limits? (2.1.2) Are personnel sufficiently trained and experienced? How often should monitoring be carried out? (2.1.3) (2.4.2) What are the operational and/or management objectives Are licences required? (2.4.3) for the site? (2.1.4) Is specialist equipment required and available? (2.4.4) Are there external factors that may have significant Are there health and safety issues to consider? (2.4.5) impacts on the site? (2.1.5) What monitoring has been undertaken, and are baseline DATA RECORDING AND STORAGE (2.5) surveys required? (2.1.6) How will data be recorded in the field? (2.5.1) Should the site be subdivided into monitoring units? How will the data be stored? (2.5.2) (2.1.7) Who will hold and manage the data? (2.5.3)

SELECTION OF METHODS FOR MONITORING DATA ANALYSIS, INTERPRETATION AND EACH ATTRIBUTE (2.2) REVIEW (2.6) Is the method likely to damage the environment? (2.2.1) Who will carry out the analysis and when? (2.6.1) Are samples required? (2.2.2) How will the data be analysed? (2.6.2) Will the method provide the appropriate type of What statistical tests are appropriate to analyse the measurement? (2.2.3) data? (2.6.4) Can the method measure the attribute across an Is transformation of the data necessary before statistical appropriate range of conditions? (2.2.4) analysis? (2.6.4) Is the method prone to substantial measurement What statistical packages are available for the analysis of error? (2.2.5) data? (2.6.6) monitoring a habitat will involve the monitoring of 2.1.2 What is the objective for each its constituent species. feature? Identifying notified features should be straightforward for Special Areas of Conservation (SACs) For each interest feature to be monitored, and Special Protection Areas (SPAs), as a list of fea- an objective should be defined that identifies tures is drawn up during the designation process. appropriate attributes of the feature and, where Identification of notified features may be more dif- possible, sets a target for each one. Each target ficult on Sites of Special Scientific Interest (SSSIs) for may include an upper and a lower limit, within which the citation may be imprecise or based on an which the feature is considered to be in acceptable early version of the selection guidelines. For clarifi- condition. cation, refer to the guidelines for the selection of Attributes of a habitat may reflect a number of biological SSSIs (NCC, 1989;Hodgetts,1992;JNCC, properties of the feature, including aspects of 1994) and contact the relevant country agency. quantity (e.g. size or number of individuals), 2.1 Setting objectives 9

Box 2.2 Examples of attributes that may be Quality: dynamics used to define the condition of habitats and succession species reproduction or regeneration cyclic change and patch dynamics HABITAT ATTRIBUTES Quantity Quality: function area physical and biochemical (e.g. soil stabilisation, carbon Quality: physical attributes sinks) geological (e.g. presence of bare rock or deep peat) ecosystem (e.g. net producer) water (e.g. presence of open water or depth of water table) SPECIES ATTRIBUTES Quality: composition Quantity communities presence/absence richness or diversity range typical, keystone or indicator species population size presence–absence frequency frequency number/density number or density cover cover Population dynamics biomass recruitment Quality: structure mortality inter-habitat (landscape) scale (e.g. fragmentation, emigration habitat mosaics) immigration intra-habitat scale macro-scale Population structure horizontal (e.g. plant community mosaics) age vertical (e.g. ground-, shrub- and tree-layer sex ratio topography) fragmentation or isolation micro-scale genetic diversity horizontal (e.g. patches of short and tall vegetation) vertical (e.g. within-layer topography) Habitat requirements

composition (presence of particular species, over- (e.g. breeding success and population structure) (see all diversity, etc.), structure, function or dynamics Box 2.2). In most cases, direct monitoring of species (Box 2.2). These principles are outlined below. will generally be targeted towards measuring range There is further discussion of attributes that and abundance; more detailed studies may be con- define the condition of specific habitat types in strained by a lack of resources or appropriate skills. Chapter 5. The costs involved in monitoring population struc- Species attributes for which targets may be set ture, for example, can be particularly high. It should include range, abundance, population dynamics be borne in mind that in some cases (for example, and habitat requirements. Part III describes methods monitoring bryophytes in fragile habitats), quanti- for monitoring range (presence–absence across a tative monitoring may damage the habitat and site), abundance (population density) and dynamics hence the species, and is therefore not feasible. 10 2 PLANNING A PROGRAMME

The setting of targets and limits for attributes is or abundance of typical species or vegetation outside the scope of this Handbook as these are communities. dependent on local site conditions. The UK statu- Typical species are hard to define, but Shaw & tory agencies have produced guidance on this for Wind (1997) suggest the following: the purposes of Common Standards Monitoring. * species on which the identification of the habitat is founded; Habitat attributes * species that are inseparable from the habitat; Quantity * characteristic species; Quantity may be the simplest attribute of a habitat * species that are consistently present but not in terms of indicating its condition. However, in restricted; many situations habitats and communities are not * species that are an integral part of the habitat; and objectively or precisely definable and there is con- * keystone species (Jermy et al., 1996), which signifi- sequently some doubt about where boundaries lie. cantly influence the habitat’s structure and func- This can make habitat quantification and interpre- tion. (Note: such species may include animals as tation of change difficult. None the less, especially well as plants.) for EIA studies, this is important if habitat area is to be lost and needs to be replaced according to some Diversity indices (Magurran, 1983) are not normally criteria. recommended for habitat condition monitoring as the setting of targets and interpretation of changes Quality: physical attributes in these indices is difficult. Certain physical attributes of a habitat can be In some cases it may be appropriate to monitor considered to be essential or desirable in their ‘indicator species’. The presence and/or abundance own right. For example, the presence of peat is an of such species may be used to indicate favourable essential attribute of blanket bog. Similarly, the or unfavourable ecological conditions that may presence of grikes is a characteristic attribute of be difficult or costly to detect by other means. For limestone pavements. example, aquatic plants can be used as indicators of It is often difficult to decide whether physical overall water quality (Palmer et al., 1992). Care properties are direct attributes of a habitat or should be taken with the use of indicator species, factors that may influence it. For example, are the however, as they may not always be reliable chemical characteristics of river water (e.g. nutrient (Rowell, 1994). status and pH) attributes or factors that influence There are a number of parameters that may be other aspects of the habitat such as macrophytic appropriate for target setting and measurement communities? In principle, in habitats in which when monitoring the abundance of typical (or such distinctions are difficult, key factors that may other) species. These are described below. influence the habitat should be monitored. Presence or absence Quantity: composition The simplest target for a species is that its presence The composition of a habitat in terms of its com- at the site, or at a defined location within it, is munities and species is a fundamental attribute of maintained. This is normally straightforward to habitat condition. Many statutory sites are notified monitor, but there are occasions when difficulties because of the presence of particular vegetation may arise: for example, for species that are incon- communities and therefore monitoring should spicuous, difficult to identify or rare, or those that ensure that targets for these are being met. inhabit inaccessible areas. Monitoring all species is clearly not feasible in The distribution (range) of a species across a site all but the simplest habitats. Therefore, the most can be monitored by assessing presence–absence commonly used species-based attributes of habitat across a number of locations (e.g. grid squares), composition are species richness and the presence and distribution maps can be drawn up for such 2.1 Setting objectives 11

surveys. Repeat presence–absence surveys can indi- monitoring because of the difficulties of defining cate expansions or contractions in range. individuals of clonal or rhizomatous plants (White, 1979) and the amount of time required to count Frequency numbers accurately in large sample sizes. However, Frequency is the proportion of quadrats (or other sub-plot frequency is often used as a quicker alter- sample units) examined in which the species is native. Densities depend on reproduction, disper- present. Frequency is a simple, quantitative mea- sal, population ages, etc., which may vary from sure, and has been widely used to describe relative year to year. These annual variations in population abundance. With a large number of sampling sizes mean that samples have to be recorded regu- units of sufficiently small size, frequency estimates larly to separate normal fluctuations from direc- of plant species can approximate to cover (see tional change. below). For plants, there are two measures of fre- Density estimates can be converted to total quency: shoot frequency (the presence of any foli- population size estimates by multiplying the den- age within the quadrat) and root frequency (the sity by the area of similar habitat. Alternatively, presence of rooted individuals only). Frequency total population counts over an area may be used estimates depend on the size of the quadrats and to derive density. Extrapolating density estimates of individual plant species (large plants may be from a smaller area to a larger one is only mean- over-represented compared with small plants) and ingful if the larger area has the same characteristics the spatial distribution of individuals of a species as the area from which the density was originally (clustered species may be under-represented com- estimated. When making such extrapolations you pared with more widely spaced ones). Frequency need to be sure that all individuals are detected or measures may also exaggerate the apparent bio- that a detectability function can be estimated: see mass of small species and hence overestimate Section 10.6 for more details. their functional significance. Changes in frequency are relatively insensitive Cover to seasonal or management changes, and therefore Cover is a measure of the area covered by the above- a large sample size is required to be effective for ground stems and foliage of a plant species when monitoring change in the short term. However, viewed from above. Greig-Smith (1983) defined frequency estimates are relatively free of observer cover as ‘the proportion of ground occupied by a error and hence are particularly useful for general perpendicular projection onto it of the aerial parts habitat condition monitoring purposes. of individuals of the species’. The sum of cover A useful extension of the simple frequency mea- values from all species in layered vegetation often sure is to record presence–absence within subdivi- totals more than 100%. Cover is usually described sions of each plot. For example, a plot may be divided as a percentage, or by using one of the numerous into a 5 5 grid giving 25 subdivisions. The measure categorical indices available (see Shimwell, 1971). recorded is the proportion of subdivisions contain- The most widely used of these is the Domin scale as ing the species of interest. This will be more sensitive used in the National Vegetation Classification to change than simple frequency and is often quicker (NVC) methodology (Rodwell, 1991 et seq.). (Box 2.3) to record than cover. Within this Handbook, this Cover estimates provide a good description of the measure is referred to as sub-plot frequency. contributions of each species to the vegetation; as long as measurements are accurate, they are sensi- Density tive to short-term fluctuations in season or man- Density is the number of individuals per unit area agement. However, cover estimates, whether (e.g. plants within the habitat). Counts of numbers percentages or scales, are prone to bias and con- of individuals in quadrats have been widely used siderable care is required to ensure accuracy and for demographic studies, but less so for vegetation consistency. 12 2 PLANNING A PROGRAMME

Box 2.3 The Domin scale 5 11%–25% Domin scale Equivalent percentage cover 4 4%–10% 10 91%–100% 3 <4% – frequent 9 76%–90% 2 <4% – occasional 8 51%–75% 1 <4% – rare 7 34%–50% + Insignificant: normally 1–2 individuals 6 26%–33% with no measurable cover

complexity increases with decreasing scale, the sett- Biomass ing of meaningful targets and their measurement Biomass is the contribution of each species mea- becomes increasingly difficult. The inclusion of sured by weight (both fresh weight or dry weight microstructural attributes of habitats is therefore can be measured). Biomass estimates are useful beyond the scope of most monitoring programmes. for assessing productivity, but normally require destructive sampling where vegetation is concerned. Quantity: dynamics Usually, only aerial parts of plants are collected. Habitats are never static and therefore monitoring must ensure that essential dynamic processes are Quality: structure functioning adequately. For example, vegetation Structure is an important attribute of a habitat that surveys can indicate insufficient regeneration in can be measured at a variety of scales. Inter-habitat individual species or whole vegetation commu- or landscape-scale structure may be important nities. Some habitats will require areas that are where, for example, fragmentation alters habitat temporarily altered, for example by fire or storms, structure and ecological processes and thereby to allow regrowth of young vegetation. This is reduces the suitability of an area of habitat for particularly important in woodlands, where gap typical species. In contrast, some ecological pro- dynamics affect the species composition and struc- cesses and species may require mosaics of differing ture of stands. habitats. In some cases it is important to ensure that suc- Intra-habitat structure is also often a fundamen- cessional habitats change in specific directions and tal attribute of habitat condition, which itself occurs at desirable rates. at a variety of scales. At the larger scale, vegetation community mosaics may be a distinctive feature of Quantity: function a habitat (e.g. bog pool and hummock communities Processes (e.g. peat formation or dune formation) are in some blanket bogs). Vertical structure is also highly important ecosystem functions. However, important, especially in woodlands, where three such processes are difficult to define and even or more layers of ground flora, shrubs and canopy harder to monitor and assess. Thus, although these vegetation may be found. are important attributes, it is frequently impractic- There is probably no practical lower limit to the able to use them for monitoring habitat condition. size of significant structural variation within habitats, as micro-scale variations in vegetation cover, Species attributes height and layering may be important components Quantity of habitat condition, especially for species with Species may have minimum viable population sizes specific habitat requirements. However, as the (Soule´, 1987): the number of individuals below potential variety of structural attributes and their which the population cannot persist. Minimum 2.1 Setting objectives 13

viable populations should therefore provide the * number or density basis for establishing minimum quantities (lower * cover (for plants) limits) for species. Unfortunately it is widely felt These are discussed under the assessment of habi- that there are usually too many unknowns (in tat composition above. The choice of which mea- terms of both theory and data) to make judgements surement to use will depend on the characteristics on what those lower limits might be. Furthermore, of the target species (see Part III). the use of the concept is complicated by the fact It should be remembered when setting objec- that sites will not normally hold discrete and iso- tives for the abundance of a species at a site that lated populations. it is often very difficult and time-consuming to Minimum desirable populations (the minimum establish absolute population numbers, whether population that is considered to be safely above by total counts or by sampling (see Section 2.3). the minimum viable population) for species are Objectives for abundance should be based on sim- identified by judgement and consensus. Because ple and efficient population index-based measures they are normally based on estimates it is advisable if such assessments are adequate for defining to adopt the precautionary principle, so they should condition. always be well above the likely range of any minimum viable population. Population dynamics Trends in population size and range are there- The dynamics of, and overall trends in, population fore central to the conservation status of a species size depend on the balance between recruit- and are also relatively simple to monitor. Species ment, mortality, emigration and immigration. that are decreasing as a result of habitat changes Recruitment and mortality are of particular impor- may become rarer by two means: tance to the condition of the population. These 1. restriction of their geographical range; must at least balance if the population is to remain 2. reduction in their density. stable and hence in acceptable condition. However, the population at a site may appear stable, yet may In an ideal situation, a species’ condition on a be dependent on immigration to offset poor pro- site would be judged by determining whether it ductivity. As such, if deaths are greater than pro- had achieved targets set for its population size, ductivity the population acts as a ‘sink’ and this can rate of change, and levels of recruitment and mor- be regarded as being in an unacceptable condition tality (Davies & Yost, 1998). However, there are (but see Figure 2.3). Conversely, a population may generally insufficient data or resources to allow act as a ‘source’ if more young are produced than measurement of recruitment or mortality, and are able to breed at the natal site. When consider- too little information on ‘acceptable’ rates of popu- ing the balance of recruitment and mortality, lation change to be able to use this as part of an source and sink populations therefore need to objective. Natural variation in populations is also be taken into account. To ensure a long-term poorly documented and therefore difficult to incor- underlying favourable population trend (i.e. stable porate into definitions of condition for many spe- or increasing) and to ensure that populations are cies. One example in which population change self-sustaining, it is desirable to measure recruit- rates are being used at the site level, however, is ment and mortality. in the application of ‘alert limits’ for wildfowl The following variables may have a bearing on populations (Atkinson et al., 2000). the population dynamics of a species, and can be Measures for directly or indirectly assessing the used as measurable attributes of species condition population size of a species are: where appropriate:

* presence–absence * number of offspring produced by parent(s), * range e.g. seedling germination for trees or the number * frequency of young fledged per pair for birds; 14 2 PLANNING A PROGRAMME

Time 1: Eight areas of suitable habitat, for a species, four of which are Sink occupied (grey circles) Sink

N N Source X Time 2: Two colonies have become extinct X (X); the species has colonised two more areas (N), with the overall population size remaining stable

Sink Source If some of the habitat areas are lost (black circles) and the species cannot disperse over a sufficient distance, isolated colonies cannot be recolonised if a Figure 2.3. Source and sink populations. The population becomes locally extinct. The species is therefore at a greater source–sink model, (Pulliam, 1988) is an elaboration risk of extinction in all remaining areas. of the metapopulation model, in which habitat In the example here, only two of the remaining populations are close enough patches vary in their quality and hence their ability to to allow dispersal. Populations at the other support populations. Patches of good-quality habitat, two areas cannot be replaced if they die out. known as sources, have a net positive population Figure 2.2. Metapopulation structure and the effects growth. Patches of poorer habitat, known as sinks, of habitat fragmentation. have a net negative population growth. Source populations increase until their carrying capacity is reached, whereupon individuals disperse to sink * longevity; and habitats. Without this dispersal, the sink populations * mortality rates (these may vary at different life would die out. However, sinks provide habitat for stages: mortality of young is often higher than surplus individuals from sources, and these that of adults). individuals can recolonise sources in the event of extinctions of source populations. The existence of Population structure sinks therefore increases total population size and the Age and sex persistence of both source and sink populations. The ratio of different age classes of a population may be an attribute that defines condition. For habitat fragmentation. Such small sub-populations example, if the mean age of a population is have a much greater chance of extinction because increasing, it indicates that recruitment is prob- of random demographic accidents and local envir- ably failing; if such a trend persists, the popula- onmental variations. Therefore, persistence of tion may go into decline (if it is not already doing such sub-populations may be dependent on other so). The sex ratio can also be important, particu- viable breeding sub-populations occurring within larly if mortality rates vary between the sexes. the effective dispersal distances undertaken by This is often the case for species that exhibit immigrating and emigrating individuals. Thus, marked behavioural differences between males the population as a whole exhibits a metapopu- and females. For example, female bats are more lation structure (see Figure 2.2). at risk of catastrophic mortality when they gather Although some species such as the Marsh in maternity roosts. Fritillary butterfly Eurodryas aurinia are thought to exhibit metapopulation structures, understanding of the processes within such populations is Fragmentation or isolation generally poor. It is therefore not normally possible Many populations are composed of a number of to define condition reliably with respect to meta- partly isolated sub-populations, often as a result of population structure attributes in such species. 2.1 Setting objectives 15

Instead, the general aim should be to ensure that availability of suitable micro-habitats is important wherever feasible all sub-populations are ‘source’ for many invertebrates, lichens, fungi and other populations, through provision of ‘optimal’ habitat species. Guidance for monitoring micro-habitats conditions, as opposed to ‘sink’ populations is not specifically provided in Part II; however, pro- (Figure 2.3). vided the characteristics of the micro-habitat are known, it should be possible to adapt the methods Genetic diversity in Part II for monitoring some aspects of these. The Conservation strategies should be aimed at conser- abundance and availability of prey species are also ving genetic variability within species as well as components of habitat quality: guidance on mon- conserving the species themselves. The assessment itoring these may be obtained in Part III. of genetic diversity in detail is a scientifically complex procedure, which is beyond the scope 2.1.3 How often should monitoring be of a general species monitoring programme. carried out? However, genetic diversity can be conserved by ensuring that separate populations or races of spe- The frequency with which monitoring should be cies are conserved. For some species, morphologi- carried out should be established at an early stage cally distinct races can be identified without the in the development of a monitoring programme. need for complex analyses (e.g. the Fair Isle Wren Although, within the conservation agencies’ Troglodytes troglodytes fridariensis); conservation and Common Standards framework, notified features monitoring can be targeted towards these. For the need only be assessed once every six years, it is highly majority of species, genetic diversity does not often desirable that monitoring be carried out with suffi- manifest itself physically between populations, but cient frequency to detect changes before they result conservation of separate populations will help to in a feature’s condition becoming unacceptable. At conserve within-species diversity. The introduction the very least, it is clearly essential that monitoring of individuals from outside the natural range of a be frequent enough to ensure that changes are species should generally be avoided, as this can detected before they become irreversible. reduce the genetic distinctions between popu- The timescale over which changes are likely lations (for example, many lowland chalk streams to occur and be detectable will vary according to formerly contained endemic races of Brown Trout the feature in question. In particular, the intrinsic Salmo trutta, most of which have been lost through rate of change is of fundamental importance. For the interbreeding of races following re-stocking example, major structural changes may normally with and competition from introduced Rainbow be very slow in a woodland but potentially rapid Trout Oncorhynchus mykiss). However, it could also in sand dunes. Long-lived species (e.g. perennial be argued that isolated and inbred populations may plants such as trees) will exhibit changes in abun- benefit from the introduction of genes from other dance over a much longer period than will short- populations. lived species or species that live in ephemeral habitats. Attributes also vary according to their Habitat requirements likely rate of change. For example, the extent of a The EU Habitats Directive recognises that favour- habitat may change very slowly, whereas typical able conservation status is dependent on the avail- species of conservation importance may decline ability of sufficient habitat. Although these are rapidly as a result of inappropriate management. not strictly attributes of a species, habitat quality General indications of the optimum timescale for and quantity should therefore also be taken into monitoring various attributes of specific habitats account and monitored when defining condition according to their intrinsic rate of change are proof a species. General aspects of habitat condition vided in Chapter 5. Recommended frequencies of monitoring, such as physical vegetation type and species monitoring are given in the sections on indi- structural attributes, are covered in Part II. The vidual species. 16 2 PLANNING A PROGRAMME

Extrinsic factors may also influence a feature; Habitats and species likely to change over time monitoring programmes should therefore incorpo- as a result of planned management actions should rate sufficient flexibility to deal with unforeseen be identified, as well as the likely timescale of and potentially rapid and catastrophic events (e.g. change in years. For example, it may be a manage- storms and fires). Additional monitoring may be ment objective to coppice a woodland area for required to establish the condition of a site after invertebrates and ground flora. Ideally, the two such events. More extensive and detailed surveys to groups should be sample-surveyed before and establish new baseline conditions may be neces- after management, and for a series of years up to sary if damage has been extensive and features canopy closure again. Monitoring of habitats and have been partly or wholly destroyed. species should tie in directly with the management In addition to these biological considerations, objectives and actions. This is important if the cost- determination of the frequency of assessment should effectiveness of management is to be maximised also take into account the minimum required report- and objectives achieved. ing frequency and available financial resources. Therefore, an appropriate procedure for determining 2.1.5 Are there external factors that may surveillance frequency might be as follows, have significant impacts on the site? 1. Select an interval consistent with: Habitat and species condition may also be affected * the intrinsic rate of change of the feature, taking by external factors, such as airborne pollution or into account the precision with which that climatic change. These may therefore also require change can be measured (see Sections 2.2.3 and monitoring. However, because of the large scale of 2.2.4); some of these processes, monitoring may only be * the timescale dictated by reporting require- feasible at a selection of sites. Data from existing ments; and monitoring schemes (e.g. Meteorological Office * the availability of funds for surveillance. weather stations) may also be suitable. The avail- 2. Aim to make a detailed assessment of the attribute at ability of existing data on such factors should there- the required interval (for example, for woodland fore be carefully investigated before including area, aerial photography may be required at inter- them in monitoring programmes. vals of 10 years). Detailed descriptions of methods for monitoring 3. Assess the risk of change from external factors. management actions and external impacts are Aim to make a basic inspection of the attribute more beyond the scope of this Handbook. However, brief frequently for signs of abrupt change due to extrin- summaries of key management measures and sic factors (for example, for woodland area, a basic external factors influencing habitats are provided inspection at intervals of three years may be in Chapter 5, together with sources of further appropriate). information.

2.1.4 What are the management 2.1.6 What monitoring has been objectives for the site? undertaken and are baseline surveys required? In addition to directly assessing the condition of features of interest, monitoring should, where A baseline survey is carried out to determine the resources permit, establish whether management habitats and species present on a site and their objectives are being met. Ongoing management current condition. If a baseline survey of features objectives and associated actions should therefore and their attributes has not been undertaken, this be identified and appropriate monitoring methods will be required before a detailed monitoring pro- selected. Monitoring of management impacts is gramme can be planned. It is necessary to establish briefly covered in Chapter 5. the baseline levels of the various attributes so that 2.2 Selection of methods 17

any subsequent changes in these levels can be * one part of a feature is in particularly poor condi- identified. tion and you wish to track its recovery. It is therefore important to establish from the Unit boundaries must not cross feature boundaries; outset whether monitoring has previously been each unit should only encompass part of one fea- undertaken at the site, including the attributes cov- ture and each objective must apply to the feature as ered, the methods used, the timescale and fre- a whole. quency over which it took place and whether or A general discussion of monitoring complex not it is ongoing. It is not unusual for the results of sites is provided by Stone (1997). monitoring studies to be forgotten, especially if they are unpublished and the members of staff responsible have moved on. A careful and detailed investiga- 2.2 SELECTION OF METHODS FOR tion may therefore often be worthwhile. MONITORING EACH ATTRIBUTE Available data from previous monitoring programmes or ad hoc surveys should be used to review Once you have defined your objectives for the mon- the appropriateness of methods and sampling stra- itoring programme and decided which feature tegies employed (see Section 2.3.1). Previous mon- attributes are important, you should then decide itoring programmes should not be followed on the most appropriate methods for monitoring without careful consideration of their suitability, each attribute that defines condition for each feature. as they may have been established to meet differ- Monitoring methods for habitat attributes are ent objectives. However, if existing monitoring listed in the tables for each habitat in Chapter 5 programmes are likely to contribute to current and described in Chapter 6. Survey and monitoring monitoring objectives they should be continued. methods for species attributes are listed in the Where appropriate, existing methodologies should general methods tables for each species in also be followed to maintain the validity of long- Chapters 11–26. The methods described in these term datasets. It may also be useful to use existing sections are often specific to one particular group fixed marker systems or permanent quadrats. of species. Chapter 10 gives a general introduction Take care over the use and interpretation of to population monitoring and describes the theory historical data that have not been properly docu- behind the sampling methods most commonly mented. Grid references may be unreliable, and used. Although not comprehensive, the methods maps sometimes differ between editions and given for both habitats and species are likely to be scales. Round numbers (e.g. 100 plants) are usually the most appropriate and efficient tried and tested highly indicative of estimates. Similarly, national methods currently available. distribution maps are very poor indicators of the Clearly, to maximise the efficient use of moni- real status or change in a species (see Rich & Smith toring resources the most cost-effective method (1996) for a detailed review). appropriate to the monitoring objective should be used. Thus, quick and cheap subjective methods should be used if they are adequate. It is unaccep- 2.1.7 Should the site be subdivided into table to use cheap methods, however, if they can- monitoring units? not detect all degrees of undesirable change. Such methods may be a false economy, as in the long For ease of assessment it may sometimes be advan- term the financial cost of repairing damage to a tageous to divide habitat features into ‘monitoring feature is likely to exceed by far the costs of moni- units’. This may be useful if: toring and of early management intervention. It * features are too extensive or too fragmented to be should be remembered that the closer an attribute surveyed adequately in one visit; is to the limits that define condition, the more * you wish to assess the effects of management prac- precise the chosen method must be to determine tices that apply only to certain parts of the feature; whether it is above or below the limit. FOR EACH ATTRIBUTE TO BE MONITORED CONSIDER THE MOST COST-EFFECTIVE METHOD (See Section 2.2 and appropriate sections in Chapter 5 (Habitats) and Chapters 11–26 (Species))

Consider the next most Is the method: cost-effective method

Unlikely to damage the species or environment ∗ (2.2.1)?

Able to provide a type of measurement consistent with the target objectives for the species (2.2.3)? Able to measure the attribute across an appropriate NO range of conditions (2.2.4)?

Able to provide sufficiently precise observations to detect appropriate scales of change (2.3.2)?

YES

Is the method subject to significant bias (2.2.5)? YES

Does the bias matter for monitoring purposes NO if it is consistent?

YES

Can the bias be YES measured or controlled? NO

Are samples required (2.2.2)? Take direct measurements of entire attribute

YES

Design a sampling scheme (see Section 2.3 and Figure 2.6)

Figure 2.4. Selection of methods for monitoring each attribute (see the relevant chapter or section for further information.) *This may depend on whether sampling uses permanent or temporary plots (see Section 2.3.3). 2.2 Selection of methods 19

Selecting the most appropriate method is therefore an important step and needs to take 2.2.2 Are samples required? into account the key considerations described It is sometimes possible to make complete assess- below (summarised in Figure 2.4). If the most cost- ments of an attribute of a feature of interest at a effective method fails any of these considerations, site (e.g. by aerial photography if complete site the next most cost-effective method should be coverage exists, by Phase I mapping, or by counting assessed. the total number of an easily detectable species). In this case, complete measurements can be taken, 2.2.1 Is the method likely to damage although the accuracy of the method will still the environment? need to be considered when presenting the results. However, it is seldom possible, or even necessary, It is clearly essential that monitoring activities do to do a complete count. Unless species are very not damage features of conservation interest on a rare, very conspicuous, or very localised, total site. However, there are unfortunately numerous counts (Section 10.1) can prove too expensive or examples in which research and monitoring probe prone to under- or overcounting. This is particu- grammes have merely measured and recorded the larly true when counting mobile species such as damage caused by their own activities. Therefore, birds, or animals and plants that have a large great care should be taken to ensure that the meth- range and inhabit remote sites where counting is ods chosen will not cause any damage. In particular either impossible or impracticable. the following precautions should be strictly More commonly, it is only practicable to study observed: a sample (i.e. part of a feature), and to generalise from observations made in the sample to the * Ensure that the target attributes are not damaged whole feature. Using sampling methods allows during sampling (e.g. by trampling) and that distur- the researcher to invest more time in avoiding bance to other habitats and species is minimised. the problems with measurement error (see * Be aware of other species or groups of conserva- Section 2.2.5). Although there are a number of stan- tion importance in the area and take care not to dard methods for certain species, when designing a cause disturbance to them. new study it is advisable to tailor monitoring to * Do not use vehicles on the site unless particular achieve the most efficient and appropriate means tracks have been identified and impacts can be of data collection. Some methods are designed to avoided. standardise data collection by time (i.e. counting * Do not use destructive sampling methods unless species for a set length of time) and some by space absolutely necessary. If they are used, minimise (i.e. counting within a set area such as a quadrat). impacts and understand the extent and impor- Choosing a method will also rely heavily on the tance of the impact to the ecological community ecology of the species or habitat concerned. and the attribute being monitored. Sampling is covered in some detail in the next * Be able to relocate fixed quadrats and sampling section. locations easily in successive years or sampling periods to minimise the need for walking over the site and potentially damaging the habitats 2.2.3 Will the method provide the you are going to monitor (see Section 2.3.3 and appropriate type of measurement? Appendix 5 for further discussions). * Position fixed sampling locations sensitively The type of measurement produced by a method is and avoid or minimise damage during their particularly important and must be consistent with establishment. the objective for each attribute. For example, the * Avoid excessive revisiting of sites and sampling target for dead wood volume may be expressed as locations. ‘one or two large (>50 cm diameter) fallen trees or 20 2 PLANNING A PROGRAMME

trunks visible with plenty of 5–50 cm pieces in view that have to be visited. Presence–absence data are at each sample point’. This would require only quick to collect but provide little information that a subjective assessment is made at surveyed about each location. Thus, large numbers of loca- locations. If, however, the target is expressed tions may have to be visited to build up a picture of as ‘a mean of at least 10 m3 ha–1 of dead wood the quantity and condition of a feature at a site. across the site’, quantitative estimates based on Quantitative data can provide much more informa- density measurements at survey locations would tion and usually require fewer locations to be vis- be required. ited. However each measurement will take rather The type of data being collected will also have a longer to collect. Section 2.3 provides more infor- significant impact on the survey design and range mation on the design requirements for different of analyses that can be carried out. The most com- measurement types. monly collected types of data are as follows. Data collected for monitoring will be either a direct or an indirect measure of the attribute. A Nominal direct measure involves making measurements of Each survey location is assigned to a predefined the attribute itself. An indirect measure involves category. For example, a species may be recorded as measuring a related variable, which is used to being present or absent at a location, or a habitat may infer the status of the attribute being monitored be classified as a particular type of grassland. (for example, using counts of otter spraints as an Ordinal index of the number of otters present on a site). An extension of nominal data in which the cate- Such measurements are described as population gories are ordered. Thus, for example, the indices. An index of population size is also abundance of a plant species at a location may obtained from direct sampling of a subset of a be classified in an ordered scale such as ‘rare’, total population. For example, male moth popula- ‘occasional’, ‘frequent’, ‘abundant’ or ‘dominant’ tion size can be estimated by using pheromone (the so-called DAFOR scale). This clearly provides traps. These data are treated as an index of total more information than a nominal measure such population size, since one cannot be sure of the as presence–absence, but may take longer to numbers of females. assess.

Quantitative 2.2.4 Can the method measure To measure abundance we may instead actually the attribute across an appropriate count the number of plants present or, range of conditions? alternatively, what area of ground they cover. This The method needs to be able to measure the attri- provides a quantitative measure. Other examples are bute fully across the range of states over which the height of vegetation, the mass of an animal condition is defined. It is essential that the method and the number of species at a site. These provide has appropriate limits of detection (i.e. the level finer, more sensitive measures than ordinal data but beyond which it is not possible to measure or dis- may take longer to collect and may be prone to tinguish between presence or absence). This is measurement error. If necessary, quantitative data most relevant to measurements of chemical con- can always be converted to ordinal data by centrations, but may also affect other attributes of grouping the data into categories, e.g. 0–2 plants, habitats and species. For example, the use of satel- 3–5 plants, etc. lite-based remote sensing may be inappropriate Further information on data types can be found in for measuring changes in habitat at the site Fowler et al. (1998). level because of the limited spatial resolution If the site is to be sampled, there is usually a obtainable. trade-off between the type of data collected at As another example, grapnel trawl surveys can each sample location and the number of locations be used to detect presence–absence of most aquatic 2.2 Selection of methods 21

Figure 2.5. Bias in measurement. (a) Measurements are unbiased: estimates are distributed around the true value. (b) Measurements are biased: they tend to overestimate the true population. macrophyte species but cannot be certain of detect- this, it is important to know something about how ing some small, fine-leaved or rare species. If much error can be expected. data are required for such species, an alternative In the second set of results 2.5(Figureb) the method may have to be used. observers tend to overestimate the true popu- On the other hand, for simple monitoring pur- lation: these estimates are said to be biased. Bias is poses there is little point in using a technique that clearly of concern if we think the population is measures an attribute well beyond its range of much larger than it really is; if such error is pre- acceptable condition. For example, it is not neces- sent, we need to know about it. Bias is a systematic sary to measure sub-surface water levels (e.g. by source of error that results in under- or overestima- dipwells) if condition is merely dependent on tion of the attribute being measured. It causes esti- water levels always being well above the surface. mates to be inaccurate. Methods free of bias are said to be accurate. Of course, some observers may produce unbiased 2.2.5 Is the method prone to substantial results in a given situation, whereas others may be measurement error? biased. This possibility needs to be considered Some measurement error is almost always unavoid- if successive surveys are likely to be carried out able in ecological studies and it is important to con- by different people and accurate measurement of sider whether such error is likely to affect the value change is important. and validity of the study. An example should help Bias may arise from several sources in a study, make this clear. including: Suppose the population of Capercaillie Tetrao Observer urogallus at a site is estimated by several observers * Incorrect identification of species. independently. Each observer comes up with a dif- * Failing to detect and count all individuals of a ferent estimate because it is impossible to count the particular species being surveyed. numbers without error. Figure 2.5 illustrates two * Different observers recording identical observa- possible sets of results. In the first2. 5a)(Fi, guretions in dissimilar ways. the counts are all spread fairly evenly around the * Different observers having expertise in different true population and so on average the observers get areas, which may affect their interpretation of the it about right. The error in each observer’s estimate observations they record. may or may not be important, depending on how * Variation in observer effort (e.g. speed of good an estimate is required. To be able to judge assessment). 22 2 PLANNING A PROGRAMME

Location Hatton, 1990; Rich & Smith, 1996). These investigations show that: * Studying a species only where it is common; if areas in which it is rare have been ignored the * recorders are better at repeating their own work full dispersion of the species will not be under- than that of others; stood. Estimates of total extent across the whole * results from small areas intensively searched are site cannot therefore be made. more repeatable than those from larger areas less * Using a small subjectively selected sample area intensively searched; when the site being studied is not homogeneous. * large, broad-leaved or clumped taxa are better Habitat differences recorded than small, well-dispersed or fine-leaved taxa (Clymo, 1980; Sykes et al., 1983); and * Species of plant may be more easily detected in * quantitative work involving fully objective mea- some habitats than in others. For example, soil surements is more repeatable than work that uses type and moisture content can affect the growth subjective qualitative or semi-quantitative mea- patterns of plants. surements; visual cover estimates, in particular, * Some habitats may be more accessible to survey are often inconsistent. than others. Whether bias matters to your monitoring pro- Species differences gramme depends on the accuracy of the estimates * Some species may be more easily identifiable than required. If the bias remains consistent and an accu- others. rate estimate is not required then the bias is less important, because it will not affect your ability to Temporal sources detect change. However, determining whether the * The time of year (or day) when a survey is carried bias remains consistent or not is likely to be very out can affect the results. Season is particularly difficult. There are three ways of combating bias: important for vegetation monitoring; survey times must be standardised. 1. If the likely sources are anticipated, steps can be taken to minimise bias for a particular project. Bias Weather can be reduced or controlled in a number of ways: * Always record as much detail in your monitor- * Inclement weather affects observers’ concentra- ing as possible and use the same methods, tion and the time they will willingly spend in the approach, analysis, etc., across years, observers field. Variation between different observers’ capa- and sites; that way any observer bias can be kept city for working under difficult conditions can fairly consistent. If effort cannot be kept con- introduce bias. stant, the next best thing is to measure it. * It may be more difficult to distinguish species in * When choosing a monitoring method, check wet vegetation than in dry vegetation. whether its assumptions (see individual habitat * Many species are less active under inclement and species chapters in Parts II and III) will hold weather conditions. for the habitat or species you wish to study and By being aware of potential sources of bias these for the period of time over which it is to be problems can be reduced, measured or otherwise studied. taken into account. For example, each time vegeta- * Record relevant weather conditions when sur- tion is measured, it is inevitable that there will be veying. Agree and record beforehand at what some recording bias, even with trained observers; point weather conditions should postpone work. numerous studies document this (for example, see * Agree and record definitions (e.g. sample size, Hope-Simpson, 1940; Smith, 1944; Lamacraft, type, population unit, etc.) beforehand. 1978; Sykes et al., 1983; Nilsson & Nilsson, 1985; * Calibrate observers against each other before, Kirby et al., 1986; Rich & Woodruff, 1990; West & and during, monitoring. Introduce a system for 2.3 Sampling strategy 23

quality assurance to verify the data (perhaps by measurements are taken. For example, this may be using a person unconnected with the study or a quadrat in a habitat survey or a bird’s nest in a study by observers checking each other’s work). of breeding success. The term population is used to 2. With careful design it is possible to avoid the mean the set of all possible sample units across the problem by confining comparisons of results to site under study. Thus the population of 1 m 1m attributes that have the same bias. quadrats is the total area of the site divided up into a 3. It is possible, though difficult, to measure the 1m 1mgrid.Asample is a particular set of sampling bias. Measuring bias can be done only if the true units and associated measurements. value can be occasionally ascertained; normally The object of sampling is to avoid having to study this is unachievable. A separate experiment may an attribute across the whole site but to still be able be helpful: for example, you could compare the to estimate what is happening across the whole site. results obtained by different observers measuring As Samuel Johnson said, ‘You don’t have to eat the the same population. whole ox to know that it is tough.’ Thus we make an inference about the whole based on an examination If the bias may affect the monitoring and cannot be of only a part. For these inferences to be valid, sam- adequately measured, controlled for or reduced, pling must follow certain principles: then an alternative method should be used. If it is not possible to find one method that provides * samples must be as representative of the whole as an apparently unbiased estimate, use a number of possible; different methods and compare the results, or * more than one sampling unit is required. This is change the objectives to match what is achievable. known as replication. The first principle enables reliable estimation of 2.3 DESIGNING A SAMPLING STRATEGY an attribute’s value for the population and is usually achieved by randomly locating the sample First and foremost the design of a sampling strat- units. The second principle enables the variation egy must take into account the objectives of the between samples to be calculated and can be used monitoring study, to ensure these are met. These to estimate the uncertainty in the estimate due to objectives might be defined in terms of having only studied part of the population. For example, the area of a site covered by Heather * how ‘good’ the estimate of the attribute, for the Calluna vulgaris may be estimated by calculating whole site, needs to be; the mean area of Heather in a sample of * what level of change between surveys needs to be 1m 1 m quadrats and multiplying this figure detected; and by the size of the site in square metres. The uncer- * which sections of the site are of particular interest tainty in this estimate may be measured by the or most likely to change. standard deviation of the estimate. An account of Some other factors influencing the design are these important statistics is given in Box 2.4, below. See a lsoGlossa the ryfo r further definitions * the type of attribute being measured; of statistical terms. * the method being used; A key feature of sampling is that as the number * the variability of the attribute across the site (if of samples taken increases, so our uncertainty over known); and how closely the sample estimate reflects the true * the time and costs of sampling. population value decreases. The greater the sample Figure 2.6 summarises the steps that should be size, the greater the amount of survey time considered. The steps are described in greater required, and so a balance is needed between detail in the following sections. ensuring that the estimate is ‘good enough’ and In this account of sampling design we use the not expending unnecessary effort. Often, defining term sampling unit to mean the unit from which what is ‘good enough’ is not easy but will depend on 24 2 PLANNING A PROGRAMME

FOR EACH METHOD AND ATTRIBUTE TO BE MEASURED (see 2.2)

Are any data available on the size and variation of the attribute (2.3.1)? NO Consider a preliminary survey YES

Decide whether sample locations should be permanent or temporary (2.3.3)

Consider judgemental Is a representative sample of the sampling (2.3.4) NO attribute required? (2.3) YES

Decide whether samples should be selected randomly or systematically (2.3.4)

Is there likely to be substantial variation YES Consider stratified in the attribute across the site? sampling (2.3.4)

Will travel time between sample sites be high or Consider multi-stage does the attribute vary substantially at small spatial scales YES sampling (2.3.4) or along transects?

Estimate minimum sample size required for desired precision and/or probability of detecting change (2.3.5)

Estimate time and cost of sampling

Is sampling programme feasible NO Reconsider sampling strategy taking into account requirements for other attributes and species? OR YES Seek more resources Document methods and sampling strategy as a Standard Operating Procedure

Figure 2.6. Designing a sampling scheme. the quality of information required for the particu- precise, population estimate is likely to be required. lar feature under study and the use to which the In other situations only a quick check may be results will be put. For example, if a species of inter- needed to confirm that a population is still doing est is important and its population is believed to be well. Further guidance on establishing the number close to the limit of what is viable, then a good, or of sample units required is given in Section 2.3.5. 2.3 Sampling strategy 25

(a) Estimate mean (b)

Estimate mean

True size True size of population of population

Figure 2.7. Precision of measurements taken from a sample. In (a) the measurements are fairly precise: they are closely spread around the mean value. In (b), however, measurements are imprecise: they are widely spread around the mean.

Thesizeofsampleunitchosenwilldependonthe * the surveyor is unfamiliar with the site and/or species or habitat being sampled, the type of mea- method; or surements being made and the method used for * there are no existing data available for the site sampling. This aspect of a sampling scheme is there- that may help formulate a good sampling design. fore considered in the individual method sections in Data from preliminary trials can provide an initial Part II,Chapter6, and Part III,Chapters11–26. assessment of how close feature attributes are to Sample units for monitoring habitats and many their targets and limits, and an estimate of the species, particularly plants, will usually be quad- variation in these attributes between sampling rats (Section 6.4.2) or transects (Section 6.4.6). units. This information can be an invaluable aid Appropriate quadrat size for habitat monitoring is when deciding how best to distribute the sampling discussed in the sections on the use of the National units across the site and how many samples are Vegetation Classification (NVC) for monitoring required. Although such a preliminary trial may (Section 6.1.6) and is treated in more detail in be time-consuming, it is likely to save time and Appendix 4. Transect length for habitat monitoring resources in the long term, particularly where is discussed in Section 6.4.6. sites and their features are poorly known. Sample units for species can be varied. The use Preliminary field trials also enable the surveyor to: of total counts, timed counts, quadrats and transects, and some other generic monitoring methods * become familiar with the characteristics of habi- for species are discussed in Chapter 10. Other tat or study species on the site; methods for particular species groups are dis- * become familiar with the geography of the site; and cussed in PartIII (Chapters 11–26 ). * iron out any problems applying the method.

Larger sites tend to be more complex, with more 2.3.1 Has the method been thoroughly variables influencing the habitats, and so the larger tested and are preliminary field trials the site, the greater will be the benefits of using a necessary? field trial.

Preliminary field trials can be extremely valuable and are often overlooked. They are particularly 2.3.2 Will the appropriate level important if: of precision be achieved?

* the methodology has not been used before in Precision is a measure of the closeness of repeated similar circumstances; measurements to each other and provides a 26 2 PLANNING A PROGRAMME

measure of the uncertainty due to sampling (see variable and we have less confidence that the sam- Figure 2.7). Intuitively, if the sample measurements ple has pinned down the population mean. are all very close to each other then it is likely that Because the sample mean is our estimate of the the site is very uniform and so, provided there is no population mean, we are usually more interested in bias in the measurements, the sample mean is likely its precision rather than that of the individual mea- to be close to the population mean. Conversely, if surements. Regardless of the precision of individual the measurements vary a lot then the site is very measurements, we would expect that, as we increase

Box 2.4 Descriptive statistics: some important Variance: the square of the sample standard deviation definitions (s2). This is another commonly used measure of data variability but, unlike the standard deviation, it is not Mean: The sum () of all individual values (x) divided by measured in the same units as the observations. the number (n) of observations: (x)/n. See figure below. Standard error (SE): the standard deviation of the sam- Median: The middle observation in a set of observations ple mean, given by: that have been ranked in magnitude. s Mode: The most common value of a set of observations. SE ¼ pffiffiffi : n Standard deviation: A measure of the variability of a dataset in terms of the deviation of observations, This is a more informative statistic than the standard xi (i ¼ 1ton), from the mean. When monitoring, we are deviation when the main interest is in the sample generally sampling a subset of the population. In this mean. It will decrease as the sample size increases. case, the sample standard deviation, s, is given by: Coefficient of variation: Another useful measure of the relative variability in the data, which can be compared sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi P between different attributes regardless of the units ðx xÞ2 s ¼ i ; in which they are measured. Relative variability is n 1 measured by calculating the coefficient of variation (%cv), which is the standard deviation expressed as a where x is the sample mean. percentage of the sample mean:

%cv ¼ 100s=x:

Mode = 5

35 Median = 6

30 Mean = 7.2 25

Frequency 10

0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223242526 x

Figure B2.4. An example of a distribution showing mean, median and mode. 2.3 Sampling strategy 27

the number of measurements, so the sample means 2. Detecting changes between one survey and the from repeated samples will tend to become closer next. If small changes need to be detected then a and closer to one another and so each sample will precise estimate of change will be needed, which tend to be closer to the population mean. will usually depend on having a precise estimate Precision in the sample mean is often measured of the attribute’s value from each survey. by its standard error (Box 2.4), which becomes smal- Further guidance on establishing the number of ler as the sample size is increased (Figure 2.8). Thus sample units required is given in Section 2.3.5. precision improves as the standard error decreases. Finally, it should be remembered that simple This is not quite the whole story. As the sample monitoring methods may actually be extremely size increases, so we would expect that the sample time-consuming overall because they produce means from repeat samples will tend to become relatively imprecise results and therefore require closer and closer to one another. However, the more intensive sampling. On the other hand, sample size (n) cannot be larger than the popula- although some sampling methods appear daunting tion size (N). When this limit is reached, the sample because they use a complicated methodology, the is of the whole population, and there is then quality of data collected per unit time may be no uncertainty remaining as to the value of the much higher. population mean. So for the standard error to be a good measure of precision it should be zero when n = N, which is not the case for the formula given 2.3.3 Should sample locations be in Box 2.4. For a finite population a more exact permanent or not? formula for the standard error of the sample Permanent sample locations can provide a good mean is approach for improving precision when detecting rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi changes over time is of prime importance. There s2 n SE ¼ 1 : are, however, a number of significant disadvantages n N to using permanent locations. See Appendix 5 for further information on establishing permanent The quantity n/N is often termed the finite sample locations. population correction (fpc) and it is only when its value Permanent locations should only be used if: is greater than around 0.1 that it has much effect on the value of the standard error. If less than 10% of a * Maximising change detection is of prime import- feature is to be sampled, as will often be the case, the ance and some consistency is expected in how the fpc can be safely ignored. attribute changes across the site; or information is Larger sample sizes require more time; preci- needed on turnover and species dynamics; or the sion, as measured by the standard error, typically feature being monitored is a rare sessile species, increases only in proportion to the square root of which is confined to precisely known location(s). the sample size. Hence, to reduce by half the stan- * There is sufficient fieldwork time available for dard error obtained from 10 sample units requires marking and relocating permanent sampling about 40 units. locations, and this time cannot be more efficiently What precision is needed depends on the use to used for collecting data from a greater number of which the results will be put. Two key uses for temporary sample locations. survey data are as follows. * Sample locations are representative of the site (see Section 2.3.4 for further discussion) and sufficient 1. Determining whether the population value of the samples are taken to minimise the risk of chance attribute being measured is above or below a events reducing representativeness. limit. If this value is close to this limit it may * Provision has been made for the unexpected loss require a large sample size to be certain which of sample locations. side of the limit it really is. 28 2 PLANNING A PROGRAMME

25 (a) 20

10 No. of plots 5

25 (b) 20

10 No. of plots 5

25 (c) 20

10 No. of plots

0 75 80 85 90 95 100 105 110 115 120 125 130 No. orchids per plot

Figure 2.8. The effect of increased sample size on the precision of sample means. The data for the graphs above are taken from a hypothetical population of orchids distributed in a uniform habitat. The true population density is 100 orchids per plot (our hypothetical sampling unit), with a standard deviation (SD) of 10. This density is estimated by the mean (or average) number of orchids in the sample plots. (a) Three randomly selected plots give the mean number of orchids per plot as 94.3, with a high standard error (SE) and no clear picture of how the data are distributed. Estimates of means based on only three samples are likely to vary considerably and would therefore be imprecise. (b) The mean of 20 random plots gives a closer approximation (96.4 orchids per plot) to the true density, and has a lower standard error (2.65). (c) The mean of 100 plots (99.4 orchids per plot) is very close to the true density, with a correspondingly lower standard error (1.07). Thus estimates of means based on this high number of samples are likely to be very close to the true mean, i.e.precise.However,thecostandeffortoftaking100 samples may not be worth the extra increase in precision. This will depend on available resources. Note also that the number of orchids per plot is now revealed to be approximately normally distributed (see Box 2.7). 2.3 Sampling strategy 29

* The feature being monitored and the surrounding conservation reasons, it may also cause the samples environment will not be significantly altered or to become unrepresentative of the site as a whole. damaged. Permanent sample locations may become unrepresentative of the whole study area (assuming that they were representative initially) as a result Advantages of permanent locations of chance events that affect the locations dispro- If permanent locations tend to change with some portionately. Such events may also have perma- consistency, we are more likely to be able to detect nent or long-lasting effects, as successive changes change than when using the same number of tem- at one point tend to be correlated. Therefore, any porary locations. This is because the estimate of recorded changes will not reflect the true pattern change is based on the mean change within sam- of change over the site and may be significantly pling units rather than the change in the mean of biased. This difficulty can usually be overcome by different sampling units. The standard error of this avoiding small sample sizes. Alternatively, record a mean change will tend to be small when the units second set of samples at the end of the first mon- tend to change by the same amount. itoring period, which are used to estimate changes For example, suppose that mean species richness in the second period and so on, i.e. samples A are over 20 quadrats is 15 in one year and 10 in enumerated on the first occasion, samples A and B a subsequent survey and that the decline is fairly on the second, samples B and C on the third, and so consistent across the site. If permanent quadrats are on (Greig-Smith, 1983). used this consistency of change is apparent from the Permanent sample locations may be effectively way the quadrats change. However, if new quadrats lost as a result of unforeseeable events, such as are selected for the second survey we only have the permanent or long-term flooding of part of the site, change in mean richness in the two sets of quadrats or the growth of trees over long time periods. This to go on, and there is a greater possibility that the problem can be alleviated by recording ‘spare’ change is due to the chance location of quadrats in samples. the first survey being in richer parts of the site. Thus, with temporary quadrats, a change would need to be larger for us to be confident it indicated a real 2.3.4 Should the samples be located change across the whole site, than if permanent randomly, systematically or by quadrats were used. judgement? Permanent plots can also be particularly useful The arrangement, number, and size of samples has for monitoring sparse sessile species, such as some a critical influence on the results obtained and how lichens, which may be confined to a small part of a they can be interpreted. Not surprisingly, there site and do not spread. In this case randomly have been numerous investigations into this issue located plots would be very inefficient as most (see Greig-Smith (1983) and Shimwell (1971) for would miss the species altogether. reviews of plant surveying techniques). Various techniques have been used to position the samples. Disadvantages of permanent locations These are summarised in Table 2.1, with various Marking and relocating permanent sample loca- options relating to random and systematic meth- tions can be difficult and time-consuming. This ods described further in Table 2.2. may offset any advantage from additional precision An illustration of the different random and sys- if observations from non-permanent samples can tematic sampling strategies described in this be obtained much more quickly. Handbook is given in Figure 2.9. Surveying at permanent locations may alter or damage the attribute being monitored or its Locating samples by judgement surroundings, e.g. by trampling. Apart from the Sampling units that are located by judgement can- potential unacceptability of such damage for not reliably be regarded as being representative 30 2 PLANNING A PROGRAMME

Table 2.1. Summary of the advantages and disadvantages of different approaches to sample selection

Sample location method Advantages Disadvantages

Judgement Can be quick and simple if knowledge of Extrapolation of results to the whole habitat/species is sufficient feature or site is not valid without strong justification Samples can be deliberately taken Comprehensive knowledge of the site is around e.g. a rare species or feature of required particular importance; useful when all Statistical analysis is not valid and errors locations of a rare species are known cannot be quantified Random Requires minimum knowledge of the Collection of sample observations can be population time-consuming Easy to analyse data and compute Can result in larger errors for a given variability sample size compared with systematic sampling Systematic If the attribute is ordered spatially, there If sampling interval matches a periodic (regular) is a stratification effect, which reduces feature in the habitat (e.g. regular variability compared with random ditches), significant bias may be sampling introduced Determining sample locations is easy Strictly speaking, statistical tests are not Provides an efficient means of mapping valid, although in most cases conclu- distribution and calculating abundance sions are unlikely to be substantially at the same time affected of the entire study area. Consequently, observa- for demonstrating typical changes. However, for tions cannot be extrapolated across the site as a the reasons described above, such data should whole without strong justification, and it is not generally not be extrapolated to the whole feature valid to calculate summary statistics or perform or site. statistical tests on such data. Such samples there- Judgement sampling can, however, be informa- fore only yield information on their own particular tive if carried out by surveyors who use a thorough location. This may not matter when selecting sites knowledge of the site and of the processes acting for monitoring rare and/or sessile species with on the site to describe the site in an intelligent way. known locations or habitat preferences. The usefulness of the results can be increased if the Temporary sampling locations are rarely placed surveyors record as much detail as possible about by judgement except during NVC surveys (Section what they did, and take photographs. If this is done 6.1.6), in which quadrats are placed on ‘representa- well it may be possible to repeat a survey quite tive’ stands of vegetation to assist with the identi- closely. However, it is preferable not to rely on fication of NVC types. Data from such samples subjective techniques such as this. should not be used for monitoring purposes. It is fairly common practice to locate perma- Random sampling nent plots by judgement, particularly when mon- When the goal of sampling is to provide an indica- itoring rare species that are likely to be missed by tion of what is happening across the whole site, random or systematic surveys. Data collected random sampling designs are generally recom- fromsuchplotscanbeinformativeanduseful mended. Random sampling is usually designed to 2.3 Sampling strategy 31

Table 2.2. Summary of the advantages and disadvantages of different random sampling designs

Type of structure Advantages Disadvantages

Simple random Selecting sample units is quicker and Estimates will be less precise on hetero- easier than for other random designs geneous sites than with stratified sampling Statistical analysis of data is Travel time between sample units can be straightforward high Stratified Ensures that all the main habitat types If strata have not been identified prior to present on a site will be sampled (if monitoring, preparation can be time- defined as strata) consuming Characteristics of each stratum can be The most appropriate stratification for a measured and comparisons between site at one time may have changed when them can be made repeat surveys are carried out; monitoring efficiency may therefore also change Greater precision is obtained for each stratum and for overall mean estimates if strata are homogeneous Multi-stage or Can reduce sampling times, thus When calculating overall means, etc., cluster increasing efficiency larger errors are obtained than with a Useful for sites that are heterogeneous at simple random sample of comparable small spatial scales and for studying gra- size if sample units within major units dients along transects are highly correlated

ensure that each of the population of sampling quadrats, and many of the same considerations units has an equal chance of being selected. apply. The direction of fixed-length transect lines Standard statistical methods can then be used to should usually be randomly allocated. However, it analyse the data (see Section 2.6). Plot location may be desirable to select a direction that allows should not in any way be influenced by any prior samples to be taken along a perceived environmen- knowledge. Randomly located plots are picked tal gradient (e.g. a transition from acid to calcare- fromanumberedlistofallplotsthatcouldbesur- ous grassland). This has the effect of reducing veyed, by using random numbers generated by a variation between transects, thereby improving computer or from tables. Locating plots by eye does precision. not yield randomness, because samples are usually Sometimes it is impossible not to deviate from spaced too evenly. Throwing quadrats to obtain loca- randomness when sampling, for instance if access tions, although better than locating by eye, does not to a particular area is not possible. If the inaccessible achieve true randomness either (this is known as area is small this may not matter, but if significant haphazard sampling). Random samples can, how- bias is possible, the issue should be documented and ever, be time-consuming to locate in the field. population estimates may need adjustment. Figure 2.10 shows a method for choosing sampling units randomly. Units that are found to fall Systematic sampling outside the area are ignored. It is often convenient to take samples at regular inter- Transect lines may also be located by utilising vals, for instance at fixed distances along a river. these points. Transects are essentially long, thin However, this method creates one main problem: if 32 2 PLANNING A PROGRAMME

(a) Random sampling (b) Stratified random sampling

a q a r b b b b s p q r c c c c s p q r c t d d d d s p q r d t e e e e s u q r e t

(e)Cluster sampling (two types) (f) Two-stage sampling

B A

Figure 2.9. Different types of sampling strategy. (a) Random sampling: samples taken randomly from the whole study area. (b) Stratified random sampling: study area divided into strata and random samples taken in each stratum. (c) Systematic sampling: samples taken at regular intervals. (d) Stratified systematic unaligned sampling: study area subdivided into equal blocks and x co-ordinates (a–e)andy co-ordinates (p–u) generated randomly. Distance a is used in every block in the first row, b in the second row, etc. Distance p is used in every block in the first column, q in the second column, etc. (e) Two types of cluster sampling. In type A cluster areas (large squares) are chosen randomly and all sample units (x) sampled in each. In type B points are chosen randomly and samples taken in a fixed pattern relative to each point. (f) Two-stage sampling: major units (large squares) chosen randomly and minor units (x) sampled randomly from each. Major units may also be transects. 2.3 Sampling strategy 33

et al., 1990;Watt,1997) without causing substantial 8 X problems, unless a systematic bias such as that out- 7 lined above occurs. Sophisticated statistical techniques have been developed for spatial analysis of 6 both systematic and random samples (Cressie, 1993; 5 S Webster & Oliver, 2001), which enable distribution and density maps to be developed as well as providing 4 S alternative estimation methods. 3 Systematic sampling can be useful because sample sites are relatively easy to select and relocate, 2 and the approach is often more appealing and 1 X straightforward to surveyors. A particular use may be when trying to map both distribution and total 12345678 abundance of an organism across a study area. The Figure 2.10. Choosing sample units from a advantages of a regular distribution of sample sites two-dimensional map. As an example, consider might then outweigh the population estimation choosing 1 ha sample units from a woodland. The disadvantages, for example, if a distribution map shaded area in the diagram represents the woodland; based on a regular grid were the objective of the the lines superimposed on it are 100 m apart. Number study. Grid surveys repeated regularly can provide the grid rows and columns (as above). Select pairs of excellent comparative data to identify potential random numbers by using a random number generator. causes and influences of change. The first number defines the column in the grid; the second defines the row. Reject any grid squares that fall What are the advantages of stratified, cluster outwith the study area. This procedure can be carried and multi-stage sampling? out within a spreadsheet or Geographical Information Stratified sampling System (GIS). An obvious advantage of using a GIS is that Stratified sampling is very commonly used in itcanproduceamapofthesamplelocations.Onthe environmental monitoring as a way of improving ground, sample units are most easily located by using the precision of estimates. Very often there is a Global Positioning System (GPS). Small errors inherent substantial variation across the site in the feature in GPS readings are not important provided these are attributes being measured. This may be due to random. environmental gradients or differences in management, for example. In this situation it makes sense to divide the site into sub-units (strata) that the sampling interval constantly coincides with a relate to the different values of the attributes particular regularity in a species or habitat being being monitored (e.g. different densities of a par- monitored, the results will be biased. For example, if ticular species) and sample each sub-unit sepa- you are sampling vegetation at 10 m intervals, and rately (see Figure 2.9). Separate estimates are this interval coincides with the raised parts of a hum- then made for each stratum, which are then mock–hollow microtopography (perhaps stretching combined to provide an estimate for the whole the example!), the vegetation in the hollows (which site. Stratification has a number of potential may be different) will not be sampled. The results will advantages: therefore give a biased picture of the vegetation. Systematic samples are not placed independently of * An attribute can be estimated with greater preci- each other (unlike random samples) so, strictly, sta- sion, provided that the value of the attribute tistical analysis is not valid. However, if a large num- differs substantially between strata and there is ber of samples are taken, systematic samples can more variation in the attribute between strata usually be treated as random samples (Schaeffer than within strata. 34 2 PLANNING A PROGRAMME

Box 2.5 Optimal allocation of sampling effort The proportion of sampling effort that should for stratified sampling optimally be made in the hth stratum (considering variability and cost) is given by: ffiffiffiffi First we require: p nhðoptÞ PNÀÁhsh= ch n=total number of sampling units required ¼ pffiffiffiffi : n Nhsh= ch (e.g. quadrats). For each stratum (h) we require: If the measurement is a proportion (e.g. the proportion nh(opt) = optimum number of units to be sampled in of quadrats containing a species), this formula can be stratum h; written as pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Nh = total number of possible sampling units in nhðoptÞ Nh phqh=ch stratum h (the stratum area can be used instead); ¼ Ppffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ; n Nh phqh=ch sh = estimated standard deviation of measured variable per sampling unit in stratum h; where c = relative cost of taking one sample in stratum h (e.g. h ph = estimate of the proportion being measured, in c1 =1,c2 = 1.5, c3 =2) stratum h; It is important to note that an estimate of qh =1–ph. standard deviation of the variable being measured As a rule of thumb, for quantitative data no fewer must be made in advance for each stratum. This can be than five samples should be allocated to each strata. done either by making an educated guess or by For proportions rather more are advisable as, conducting a preliminary survey. In the absence of otherwise, the estimation of the standard deviation better information, costs are often all assumed to becomes very unreliable. be the same. For further detail consult Cochran (1977).

* Separate estimates can be made for each stratum If the cost of sampling varies, or the within- if these are of interest in their own right. stratum variance in each stratum differs, sampling * Stratification slightly reduces the time taken to should be more intensive in the strata in which randomly locate samples. the costs of sampling are lower or which are more variable. Sample size should be proportional to To maximise the benefits of stratification the site the size of the strata if the costs and variances of should be subdivided in such a way that it mini- each stratum are similar, or in the absence of mises the within-stratum variability in the attri- such information. A formula for the optimal bute being measured (i.e. strata should be as allocation of sampling effort between strata is pro- uniform, or homogeneous, as possible). This nor- vided in Box 2.5. Methods for calculating overall mally requires previous survey data or a prelimin- means and confidence intervals are provided in ary survey to be carried out. Box 2.13. Alternatively, you can stratify according to known site variations in habitat or ecological Multi-stage and cluster sampling factors, which are believed to influence the fea- In many situations a site may be so large that a high ture attributes (e.g. a sudden change in soil type). proportion of time is spent travelling between sam- Although these divisions are not going to be as ple sites. In this instance cluster or multi-stage accurate, as long as there is lower variability sampling could be considered as a means of increas- within strata this sampling method will provide ing sampling efficiency and in some instances can better results than simple sampling across the improve precision for a given sample size. Multi- whole site. stage sampling is also known as multi-level sampling 2.3 Sampling strategy 35

or subsampling. With multi-stage and cluster sam- relative cost of sampling at the two stages is required. pling a major sample unit is selected, which is divided This may be obtained through a preliminary survey, up into minor units. Data are then collected from or estimated based on available knowledge of the some or all of the minor units (see Figure 2.9). With habitat in question. A preliminary survey may also cluster sampling all the minor units are sampled, but be designed to investigatetheoptimalsizeofthe with multi-stage sampling a random or systematic majorunitsastherewillbeatrade-offbetweenthe sample of minor units is selected. In some cases the benefitofhavingalargesampleofmajorunitsand minor units are themselves sampled (three-stage increasing their size to reduce between-unit varia- sampling) but two-stage sampling is the most com- tion. Formulae for estimating the optimal number mon technique. of minor and major units are provided in Box 2.6. A common example is one in which the major Methods for calculating means and confidence units are transects and the minor units are quad- limits for two-stage sampling are given in Box 2.13. rats along each transect. If all quadrats are sampled These methods assume that all minor units are of this is known as a belt transect. equal size and that each major unit contains the The main consideration with this technique same number of minor units. Table 2.2 summarises is that sample units within each major unit are the advantages and disadvantages of the different unlikely to be independent of one another since random sampling designs. For further information spatial correlation may occur (i.e. sample units are and detail on these see, for example, Cochran likely to be more similar the closer they are to each (1977) or Yates (1981). other). Unless the minor units are sufficiently far apart to avoid this, overall precision is likely to be Some other approaches mainly determined by the variation between the Stratified systematic unaligned sampling major units. In cluster sampling, the minor units This is a variation of stratified sampling that com- are usually combined and analysis is reduced to bines the advantages of random and systematic simple random sampling of the major units. This sampling. The area to be sampled is first stratified may still be advantageous, compared with simple into equally sized blocks (not strata based on habitat random sampling of minor units, if there is a sig- characteristics as in stratified random sampling). nificant reduction in the variation between sam- Samples are placed in each block by using different pling units as these units get larger. x co-ordinates for each column of blocks but the Thus, cluster and multi-stage sampling are likely same x co-ordinate within one column, and differ- to be most useful when the area being sampled is ent y co-ordinates for each row of blocks but the relatively uniform at large spatial scales and most of same y co-ordinate within one row (see Figure 2.9). thevarianceoccursatsmallspatialscales(butatscales This technique can be an improvement on stratified largerthanthesizeofthesampleunit).Transectswill random sampling because the systematic misalign- be most effective if oriented along a gradient in the ment is not subject to localised clustering. This tech- attribute being measured. For example, in a study of nique does not appear to have been widely used. The tree regeneration around woodland, the transects time taken to position samples is similar to that for may be oriented away from the woodland, assuming stratified random sampling. regeneration will decline with distance. Smartt & Grainger (1974) compared the techni- The precision of the overall estimate is primarily ques discussed above. They found that stratified affected by the variance between the mean values for techniques exhibited greater overall comparative major units and, to a lesser extent, by the variance precision than random or systematic techniques, betweenminorunitswithineachmajorunit. especially at low sample densities with clustered Precision is also affected by the number of units distributions. In this situation, the sampling strate- sampled at each level. In order to determine the gies ranked in increasing order of relative precision optimum number of major and minor units to sam- were: random, systematic (regular), stratified ran- ple, some knowledge of the two variances and of the dom, stratified systematic unaligned. 36 2 PLANNING A PROGRAMME

Box 2.6 Optimal allocation of sampling effort It can be seen from this equation that uopt increases

for two-stage sampling as tm/tu increases and as the variance within units (ms ) 2 increases relative to the variance between units (sx ). 2 0 The following quantities need to be determined during If either uopt > U or sx ms < 1/u , then you should the preliminary survey: sample all of the minor units within each major unit, N = number of major units available for sampling; thereby simplifying the sampling strategy to basic n = number of major units sampled; cluster sampling. U = number of minor units within each major unit; If we assume that the mean approximately follows a u = number of minor units sampled within each normal distribution (Box 2.7), the number of major

major unit; units to be sampled, np, required to give a confidence u0 = number of minor units in preliminary study; interval that extends no more than P% either side of

tm= time taken to locate each major unit; the mean (Section 2.3.5), is roughly calculated by using

tu = time taken to sample each minor unit. the following equation: We then require the means and variances of each major unit. These are used to calculate the following: 2 sx np ¼ ÀÁÀÁÀÁ: x = overall mean, i.e. the mean of the major unit 1 2 1 1 x 2 sx þ ms þ P means; N u U 200 2 sx = variance of the major unit means;

ms = mean of the variances for each major unit. These two equations can therefore be used to calculate The optimum number of minor units to be sampled, the optimum number of minor units to sample within each major unit and the optimum number of major uopt, is calculated thus: vffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi u units to sample for a required precision, once initial u ttm=tu estimates have been made of the variability of the data uopt ¼ 2 : sx 1 0 and the relative costs of sampling major and minor ms u units.

Adaptive sampling One disadvantage is that the sample size cannot be Another approach to consider for features that have determined in advance; it will depend on what is very clustered distributions is adaptive sampling encountered in the initial sample. (Thompson and Seber, 1996). This involves selecting Some other sampling techniques for species, such an initial random or systematic sample. If the target as distance sampling, are discussed in Chapter 10. species is found in a given sampling unit, the adjacent sampling units are also included on the basis 2.3.5 How many samples will be required? that there is a good chance these will also contain the species. Potential advantages include: As previously mentioned, increasing sample size increases precision (see Figure 2.8) as well as the * although specialised formulae are required for cost of monitoring. Preliminary field trials or pilot estimation, adaptive sampling can provide better surveys enable the distribution of the species or precision for a given amount of effort than simple habitat to be assessed and the amount of variation random sampling; in each attribute to be estimated. This can be of * the method is more satisfying for surveyors, as enormous value in helping to optimise the sam- they do not have to ignore sightings that fall just pling design and in establishing the number of outside a sampling unit; samples required. Without a pilot survey or some * a better picture of the species’ spatial distribution data from a previous survey, sample size estimates is obtained. are usually down to guesswork. 2.3 Sampling strategy 37

Box 2.7 Probability distributions being interested in the distribution of the measurements themselves, we want to be able to say The probability distribution for a particular something about the mean of those measurements. measurement shows the probability that an individual This mean also has a probability distribution. An drawn at random from a population takes a particular important result, the Central Limit theorem, states value, or lies within a range of values. The true that as sample size increases the distribution of means distribution of a measurement across a study area is of samples will almost always converge towards a usually unknown and has to be approximated by using normal distribution, regardless of the shape of the measurements taken from a sample. For quantitative distribution of the original measurements. Of course, measures, such as vegetation height or counts of plants the more non-normal (e.g. asymmetrical) the parent in a quadrat, the distribution can be illustrated by distribution is, the larger the sample size will have to plotting a histogram, such as those shown in be for this to hold. Figure 2.8, but unless sample sizes are fairly large this In addition, although the normal distribution is may be a poor representation of the population distri- continuous it can often be used to approximate the bution. For presence–absence data the distribution is distribution of count and binary data. This simplifies defined by the probability that a sample unit will the calculations of probability for these data. contain the species of interest. In some cases a transformation, such as log or A lot of statistical analysis relies on assuming that the square root, can be used to make data fit a normal distribution of a measure can be described, at least distribution more closely and therefore facilitate the approximately, by a particular mathematical function. use of statistical methods that rely on this assumption This enables us to estimate the probability that the (see Section 2.6.4). measure is less than, or greater than, some value of For data that are normally distributed, the interest. probability that a measurement is less than a By far the most common theoretical distributions specified value does not have a simple mathematical that arise in monitoring are the normal and binomial formula. However, it can be found in statistical tables distributions. These are described below. or is readily calculated in most spreadsheet or statistical software. As mentioned above we are often more interested in THE NORMAL DISTRIBUTION the distribution of the sample mean rather than that of The normal distribution is the most commonly used the original data. The mean of normally distributed function to describe the distribution of continuous pffiffiffi data has parameters and = n, where n is the sample data. It is one of the easiest distributions to handle in size. It is convenient to standardise normally distributed terms of statistical computation. This distribution is data so that the standardised data follow a normal determined by two parameters, , the mean value of distribution with a mean of zero and a variance of one. the population, and , the standard deviation. Because The standardised mean is calculated as and relate to the population we must estimate their values by using the sample mean and standard ðx Þ : deviation. pffiffi n A normal curve is symmetrical, with the axis of symmetry passing through the mean. About 68% Usually, we do not know what the value of is: it of all observations drawn at random from a normal has to be estimated by s, from the sample. If we replace distribution will fall within one standard deviation of by s in the above equation the distribution ceases the mean; about 95% will fall within two standard to be exactly normal. In fact the standardised mean deviations. See Figure B2.7. follows what is called the t-distribution. This distribution The normal distribution has some very desirable is dependent on the sample size n, and is referred to as mathematical properties. Very often, rather than having n-1 degrees of freedom. For sample sizes greater 38 2 PLANNING A PROGRAMME

than about 30 the t-distribution is almost the same as certain character with the probability p or fail to the equivalent normal distribution and this can be used exhibit it with the probability 1 p = q. The probability as an approximation. P that, in a sample of size n, x individuals possess the The t-distribution is widely used in calculating character is given by: confidence intervals (Box 2.8) and in statistical tests n! (see Section 2.6). For t-distributed data, as with P ¼ pxqðnxÞ; x! n x ! normally distributed data, the probability that a ð Þ measurement is less than a specified value can be where ! = factorial (e.g. 5! = 5 4 3 2 1). found in statistical tables or is readily calculated in The mean and variance of the distribution are given most spreadsheet or statistical software. by np and np (1 p), respectively. These quantities can be used to approximate the binomial distribution by an THE BINOMIAL DISTRIBUTION equivalent normal distribution provided n is large and Observations that are binary (can take one of two p is not close to 0 or 1. This can facilitate the calculation values) such as presence–absence often conform to the of confidence intervals for p (see Box 2.8) and the use of binomial distribution. Individuals may possess a standard statistical tests (see Section 2.6).

68%

–2σ –1σ µ 1σ 2σ

Figure B2.7. The normal distribution curve showing one (shaded) and two (unshaded) standard deviations.

How many samples are required depends very This will typically be in terms of the amount of much on the individual sampling method, the type error or uncertainty we are prepared to tolerate. of attribute being measured, the degree of variabi- For example, suppose we are estimating the per- lity in the attribute being sampled and the desired centage of a raised bog that is covered by sphag- precision or the degree of change that must be num moss, and this is thought to be around 70%. detected. A method for establishing the number We might be content for our sample of the bog to of samples required to provide a desired level of tell us that this percentage is somewhere between precision is outlined below and methods for detect- 60% and 80%. So, in this case, an uncertainty of 10% ing change in Box 2.10. is acceptable. What error is acceptable will depend Both approaches require some understanding on the objectives for the monitoring. In some cases of probability distributions and how these are a rough and ready estimate may be acceptable if a applied to different types of measurement. This feature is believed to be well within acceptable is outlined in Box 2.7, but a fuller account can limits, but where the feature is of particular impor- be found in most introductory statistics texts tance or is the subject of some concern, a very (see, for example, Fowler et al., 1998; Sokal & precise estimate may be desirable. Rohlf, 1996). This approach suggests choosing a sample size that will give us enough measurements so we can Achieving a desired level of precision be confident that the value of the attribute lies The first question to be answered is how we specify between l and u , where the range u l is sufficiently how good we want our population estimate to be. small for our purposes. The range u l is termed a 2.3 Sampling strategy 39

pffiffiffi Box 2.8 Confidence intervals 4:08= 10 ¼ 1:29: Assuming the mean count is approximately normally distributed, the 95% If a population parameter such as the mean is confidence limits are estimated from a sample, there will always be uncertainty as to the whole-population value of the mean. l ¼ 6:2 ð2:26 1:29Þ¼3:3 and Confidence intervals derived from our estimates indicate u ¼ 6:2 þð2:26 1:29Þ¼9:1 ; a range of values within which we have some confidence the true mean lies. since, from statistical tables, for a t-distribution with A 95% confidence interval that ranges from 10 to 30 10 1 ¼ 9 degrees of freedom, p(T < 2.26) ¼ 0.025. That indicates that we are 95% confident that the true is, we are 95% confident that the true mean density of population mean lies between 10 and 30. Suppose bramble shoots lies between 3.3 and 9.1 shoots per the sample has yet to be selected, then we define upper quadrat. and lower 95% confidence limits, L and U, for the Formulae for calculating standard errors for population mean, , so that stratified and two-stage sampling are provided in p (L <U)¼ 0.05, a higher or lower level of confidence may be where p stands for probability. L and U are functions of appropriate. the mean of the sample to be selected. Once we have Presence–absence data generally conform to the our sample data we can calculate particular values of L binomial distribution (see Box 2.7). In this case, the and U; let us call them l and u. If it were possible to number of samples required to provide a given level of select many different samples then each would result precision depends solely on the proportion of all in different values of l and u, but 95% of the confidence quadrats containing the species, which is unknown. intervals calculated from these samples would contain This will also depend on the size of quadrat chosen the true mean. (Appendix 4). For large sample sizes and proportions To calculate l and u for a particular sample we need greater than 0.1 and less than 0.9 the methods to know something about its probability distribution. described above for normally distributed data are For example, for a mean that is normally distributed probably sufficient (see Table 2.5). Otherwise, exact the standardised mean will follow a t-distribution binomial confidence intervals can be calculated in a with n1 degrees of freedom, where n is the sample spreadsheet by using the method described at, for size, and 95% confidence limits are calculated as example, www.itl.nist.gov/div898/handbook/prc/ follows: section2/prc241.htm. For quantitative measurements that have a very l ¼ x ðtn1 SEÞ and u ¼ x þðtn1 SEÞ; non-normal distribution it is probably best to use where tn1 is the value of a t-distribution, T, with n 1 a data transformation so that the transformed data degrees of freedom such that p(T < tn1) ¼ 0.025. This are approximately normally distributed. Common value is used because we want a confidence interval transformations are covered in Section 2.6.4,butitis that is symmetric around the mean and so we set both important to note here that, if a transformation is p (U) to be 0.025. used, the mean of the transformed data will not For example, suppose we have counts of the number usually be the same as the transformed mean of the of bramble shoots for a simple random sample of ten original data. Thus the resulting confidence interval quadrats. The sample mean is 6.2 and the standard will be for the reverse transformed mean of deviation is 4.08. Assuming the population of potential the transformed data. See Section 2.6.4 for an quadrats is large, the standard error is therefore example of this. 40 2 PLANNING A PROGRAMME

confidence interval for the attribute we are estimating birds or juvenile population size of newts after and its calculation depends on the nature of the breeding). The best times to survey particular vege- measurements collected and their probability distr- tation types are shown in Box 6.13.Itisinevitable ibution (see Box 2.8 for more information). that some surveys will have to be carried out outside Being able to estimate the confidence interval these times, but it is particularly important that one would expect requires some knowledge about repeat sampling of habitats for monitoring pur- the mean and standard deviation of the measure- poses is carried out within about two weeks of the ment of interest. This is usually obtained from a day of the year that the original survey was carried pilot survey or from a previous, similarly designed, out. Serious bias may occur if surveys are carried out survey. Suppose the pilot study suggests the mean at different times of year. is x and the standard deviation is s. If the data are The timing also depends on what is being approximately normally distributed then, for the monitored; the best time to monitor floristic main study, we would expect the 95% confidence components may differ from the best time to moni- interval that would result from a sample size of n tor grazing impact. For example, in heathlands, the to be: best time to assess grazing impact is March–May, pffiffiffi but this is probably not a good time to assess flor- x tn1s= n: istic composition. The effect of detectability on data is important. In some cases, plants are best Thus if we want the main study to provide a counted after flowering; this avoids the possibility confidence interval that extends no more than p% of being attracted to flowering plants only. either side of the estimated mean, n should be such that 2.3.7 How will consistency be assured? 2 n > ð100 tn1s=pxÞ : For reliable monitoring it is essential that the methods used for assessing attributes are constant For sample sizes greater than about 30, tn1 can be between surveys. Therefore, before the first survey replaced by 2. is carried out a standard operating procedure (SOP), otherwise known as a monitoring protocol, should Power analysis be written, describing in detail the methods to Power analysis is a method for establishing the num- be used, so that everyone understands what is ber of samples required to detect a given change required and the methods are kept consistent with a given level of statistical certainty. Before between observers and years. Any modifications continuing we need to introduce the idea of hypoth- that are found to be necessary during the execution esis testing, which, among other things, provides a of the survey should be noted down immediately framework for deciding whether a change is likely afterwards and the SOP amended accordingly. The to have taken place. Box 2.9 provides the necessary SOP should then be followed as closely as possible introduction, an understanding of which will also in all subsequent surveys. However, if deviations be important for the account of data analysis in from the SOP are necessary, then these should be Section 2.6. recorded. Monitoring reports should ensure that the SOPs are written out in full in the methods section or 2.3.6 When should data be collected? placed in an appendix. DeviationsfromSOPsshould also be reported in the monitoring report, and the It is important that repeat sampling is carried out implications for the results and interpretation of the at approximately the same time of year each year monitoring should be discussed. unless seasonal cycles are being investigated. The When designing a SOP, consultation with the time of sampling will depend on the attribute being appropriate government agency specialist is measured (e.g. winter populations of migratory important in case a standard procedure is already 2.3 Sampling strategy 41

Box 2.9 Hypothesis testing In a monitoring study a Type II error amounts to concluding that no change is taking place when in fact Once data have been collected we are typically it is. In many situations it is preferable to err on the side interested in using them to test some hypothesis about of caution and try to limit Type I errors. However, Type II the population under study: for example, that the errors may have profound consequences in monitoring population of birds at a site is above some preset level, studies because real changes in the condition of a feature or that the percentage of a raised bog covered by may not be detected. For monitoring studies it may sphagnum moss is higher in year 2 than in year 1. therefore be prudent to follow the precautionary princi- Because our measurements are from a sample of the ple and specify significance levels above 5% at least as a site or population, we cannot test these hypotheses trigger for further studies. with certainty, but provided measurements are from a statistically representative sample we can estimate CHOOSING A TEST how confident we are that the hypothesis holds. Performing a test involves calculating an appropriate Hypothesis testing involves comparing two hypoth- test statistic and deciding whether its value is extreme eses, a null and an alternative hypothesis. Typically, we enough to warrant rejecting the null hypothesis. The want to test whether the data from the sample provide type of test chosen will depend on the type of data any evidence for rejecting the null hypothesis (usually being analysed and the assumptions that we make denoted H0) and accepting the alternative hypothesis about the distribution of the data (see Section 2.6.4 and

(usually denoted H1). Thus for example, H0 might be Figure 2.11). For example, one class of statistical test, that sphagnum cover has not changed across the site known as parametric tests, assumes that the data are and H1 that it has. Has there been a sufficiently large drawn from a particular distribution. The normal dis- change in the sample measurements of cover that it is tribution is the one most commonly used; if continu- unlikely that H0 is true and that it can be rejected? ous data are not normally distributed, they can often To see whether the collected data are consistent be transformed into a closer approximation of a nor- with the null hypothesis of no change, we need to mal distribution (see Section 2.6.4). Alternatively, non- estimate the likelihood of observing such a large parametric or resampling methods can be employed, change in a sample given that the null hypothesis is which do not make assumptions about the underlying true. If this likelihood is small then the null hypothesis distribution of the data. is unlikely to be true, and it is likely that a real The test statistic is compared with tables of values change has taken place. This likelihood is termed the derived from the appropriate statistical distribution significance level of the test and is frequently set at 5%. for the required level of significance. If the test statistic This would mean that if the null hypothesis is true only is greater (or, for a few tests, smaller) than the tabulated 1 in 20 samples would be expected to show such a large value for the chosen significance level, then we can change, suggesting that the null hypothesis is false. conclude that the null hypothesis (no difference) can be rejected. By convention, 5% is frequently used as the TYPES OF ERROR significance level, but it is useful to present the actual Whatever the significance level used there is always a level of significance at which the null hypothesis would chance of incorrectly rejecting the null hypothesis, and be rejected. A very small value would give strong this is termed a Type I error. In addition, there is always evidence for rejection, but a value around, say, 10% would a chance of incorrectly accepting the null hypothesis still raise doubts that the null hypothesis is correct. when it is false, and this is called a Type II error. After For example, suppose that the null hypothesis is true all, just because a test is not significant, it does not and the test statistic is normally distributed. If its value necessarily follow that the null hypothesis is true. For under this hypothesis lies in either of the 2.5% tails, there example, it is possible that the change in sphagnum isa95%chancethatthedatacomefromadifferent cover is quite small and that insufficient data have distribution, and so there is evidence for rejecting the been collected to detect it. null hypothesis. See Figure B2.9. 42 2 PLANNING A PROGRAMME

ONE- OR TWO-SIDED TESTS The power of a statistical hypothesis test is the

In the example above, the statistical test is two-sided:H0 probability of rejecting the null hypothesis given that is rejected if the test statistic falls in either tail of the the alternative hypothesis is true, and, in the case of distribution. These are the norm and arise, for exam- monitoring, is therefore a measure of the likelihood of ple, if the alternative hypothesis is that there has been correctly deciding that a change has taken place. a change, without specifying the direction of change. Conversely, the significance level of a test is the This is normal because we do not usually know the probability of rejecting the null hypothesis when it is direction of change in advance. A one-sided test is true. Thus it measures the likelihood of incorrectly appropriate if a one-sided hypothesis is specified in deciding that a change has taken place. This is illu- advance. This arises, for example, if we want to test strated, with an example for normally distributed data, whether an attribute is below a specified value. in Box 2.10.

Reject Ho Accept Ho Reject Ho

2.5% 95% 2.5%

Figure B2.9. Accepting and rejecting the null hypothesis. See text for details.

used for the species or habitat and to check the two repeats. Alternatively, the site may have to be suitability of the proposed monitoring method. resurveyed for a third time, or one set of results It is important to check the repeatability of the may have to be discounted. The final decision method used. This can be tested by having one should be accurately recorded so that the same observer repeat a survey immediately after another remedy can be applied in the event of the problem observer, or by the same observer conducting recurring (see p. 21). duplicate counts. The results of quality control are There is no doubt that the accuracy of interpre- useful for several reasons. Apart from highlighting tation is considerably enhanced when one recorder the occurrence of any differences that may be is involved in repeating work on one site for a long present due to the ability of a surveyor, such as in period of time. species identification, plant cover estimates, interpreting maps or using a compass, it may be 2.4 REVIEWING THE MONITORING possible to incorporate the results into statistical PROGRAMME tests. Confidence limits and standard errors can be calculated based on the variation in total counts or 2.4.1 Are there sufficient long-term mean values in order to break down the variation resources available? caused by observer bias compared with the variation due to other reasons. If major discrepancies It is important that the long-term future of the mon- are found between two surveys, the underlying itoring programme be considered from the outset; cause should be identified and corrected if possi- monitoring of some species and habitats has to be a ble. If this is not achievable, the results for the long-term undertaking. However, many projects survey on which quality control was carried out start off being too ambitious. Therefore, before may need to be taken as the average of the embarking on the detailed design of a monitoring 2.4 Reviewing the programme 43

Box 2.10 Power analysis ¼ P( z/2 < T < z/2 \H1 is true) ¼ chance of Type II error;

When testing a hypothesis we calculate the appropriate 1 ¼ P(T > z/2 when H1 is true) ¼ chance of test statistic T, and if that statistic exceeds a critical correctly deciding a change has occurred (the power value t, the null hypothesis, that no change has occurred of the test); between time 1 and time 2 (H0: 2 1 ¼ 0) is rejected where T is a test statistic that follows a standard normal in favour of the alternative hypothesis (H1: 2 1 6¼ 0), distribution and will be calculated after the data have where 1 and 2 are the population values at times 1 been collected, and z/2 is the value from tables from and 2, respectively. the normal distribution for the chosen significance

The ‘power’ of the test is therefore level, . For example, if ¼ 0.05 then z ¼ 1.645 and p(T > t \ 2 1 6¼ 0), where ‘\’ means ‘given that’. Thus z/2 ¼ 1.96. the power is the probability that the test statistic The power, 1, for a given sample size can be exceeds the critical value when the means of samples found from the following equation: from time 1 and time 2 are different (the test reaches z d=s z ; the correct conclusion). ¼ d =2

Plotting this probability against 2 1 shows how where sd is the estimated standard error of a level of the power increases as and become further apart, 2 1 change, d, for the given sample size. For i.e. we are much more likely to detect a change if that non-permanent plots, this is usually calculated by first change is large (see Figure B2.10). estimating the sample standard When ¼ 0 the probability that T > t is 2 1 deviation, s, from the pilot data. For reasonably large the probability of rejecting H0 when H0 is true: the sample sizes, sd is then usually estimated as significance level, or the probability of a Type I error. p When 2 1 6¼ 0 the probability that T t is the 2 sd ¼ ð2s =nÞ : probability of not rejecting H0 when H1 is true () a Type II error and the power is 1 . Trying different values of n will give an indication of A power analysis consists of calculating the number the sample size required to achieve a given power. of samples required to detect a given level of change for Permanent plots are more problematic in that sd will chosen values of and . depend on how consistently the plots change, which is difficult to predict. NORMALLY DISTRIBUTED DATA If plots are non-permanent and simple random The example presented here is suitable for equally sampling has been used (i.e. without stratification, sized, normally distributed samples (software is etc.), these formulae can be solved for n: available for this and other distributions; see below). 2 2 2ðz= þ zÞ s A pilot survey is required to obtain an initial estimate n ¼ 2 of the variance of the data. d 2 We need to decide what we consider to be the or acceptable probability of concluding that no change is taking place when in fact it is, and of concluding that 2 2 2ðz=2 þ zÞ P cov change is taking place when in fact it is not. The null n ¼ C2 hypothesis, H0, is that no change has occurred. The 2 alternative, H1, is that change has occurred. where s is the sample variance from the preliminary

We define: survey, Pcov is the percentage coefficient of variation

¼ P(T > z/2 or T < z/2 \H0 is true) ¼ chance of Type (see Glossary) of the preliminary sample, and C is the I error (the significance level); change to be detected expressed as a percentage. 44 2 PLANNING A PROGRAMME

It can be seen from these equations that the number of Statistical power depends on the type of statistical samples required to detect change will increase as the test chosen. One test is said to be more powerful than significance level of the test increases (i.e. as the another if it is more likely to reject the null hypothesis chance of making a Type I error decreases), the power when the null hypothesis is false. of the test increases (i.e. the test is more likely to be Power analysis is most useful when planning correct) and the variance of the data increases. The a study, at which point it is used to calculate the number of samples required decreases as the level of number of samples needed to detect a given change change required to be detected increases. with a predetermined power and significance level (e.g. to detect a 10% change in cover with a power of EXAMPLE 80% at the 5% significance level). When selecting a Let us assume that we are monitoring the number suitable significance level and statistical power, the of orchids flowering in a meadow by using simple precautionary principle should be considered (i.e. is it random sampling. The change to be detected is set at a better to conclude that change is taking place when in mean decrease of flowers per 4 m2 quadrat of 10%. We fact it is not than to conclude that no change is taking will use the conventional significance level of 5% for place when in fact it is?). and we will arbitrarily set the power of the test as 60% A retrospective power analysis can be carried out (i.e. there is a 40% chance that the test will wrongly after the study, which can be useful if a non-significant accept the null hypothesis). result is obtained (see, for example, Thomas & Juanes, A preliminary study was carried out, and the 1996). In this case, sample size and significance level percentage coefficient of variation of the number of are known; these, and the estimate of variance orchids in the quadrats was estimated to be 36.21. Using obtained from the study, can be used to calculate the

tables we obtain z0.2 ¼ z0.025 ¼ 1.96 and z ¼ z0.4 ¼ 0.25. size of change that was detectable with the desired The number of samples required is therefore: level of statistical power. Power analysis is useful because it can provide an 2ð1:96 þ 0:25Þ236:212 12807:7 indication of what is achievable for a given amount of n ¼ ¼ ; 102 100 effort. Thus it may become apparent that only very large changes are detectable with current resources and that t ¼ 128:08128: to detect small amounts of change, particularly in So roughly 128 quadrats would be needed to detect variable populations, requires a lot of effort. If this is a change of 10% in orchid numbers per quadrat at the considered at the planning stage of a monitoring 95% significance level with a power of 60%.

µ µ ≠ P (T>t \ 2 – 1 0) β

µ – µ 2 1 0 H1 true H1 true

H0 true

Figure B2.10. The increase in the power of detecting change as the change increases in extent. 2.4 Reviewing the programme 45

programme it will help to avoid the possibility that the powcase/monitor.html, but some care is needed to monitoring will fail to achieve its objectives. ensure that the assumptions made by MONITOR Performing a power analysis requires data from a are likely to be met. For an introduction to power pilot or previous survey that provides an indication of analysis, a software review and details of where variability in the measurement across the population. to obtain power analysis programs see the Software is usually needed to do the necessary Internet site www.interchg.ubo.ca/cacb/ calculations and there are a number of programs power and the US Geological Survey web page freely available. An example is DSTPLAN, which www.mp1-pwrc.usgs.gov/powcase/powcase.html; is available at odin.mdacc.tmc.edu/anonftp/. The see also Thomas & Krebs (1997). program MONITOR can be used to estimate the number Further information on this subject is also available and intensity of surveys needed to achieve a given in Rotenberry & Wiens (1985), Lipsey (1990), Peterman power for detecting trends over time. This program can (1990a,b), Muller & Benignus (1992) and Taylor & be downloaded from www.mp1-pwrc.usgs.gov/ Gerrodette (1993). programme, it is vital to assess the resources avail- excluding attributes for which monitoring is dis- able, including funding, staff time, staff expertise cretionary. However, it should be remembered that and existing equipment. This should then be taken excluding other features and attributes from mon- into account in the selection of features and attri- itoring may be a false economy. In the long term, butes to be monitored (see Sections 2.1.1 and 2.1.2) the costs of restoring habitats or species popula- and the frequency of monitoring (see Section 2.1.3). tions may far exceed the costs of monitoring and However, as a minimum, resources should be suffi- early management intervention. cient to provide an adequate standard and fre- At the outset it is important to work out how quency of monitoring for all the features and their much time the optimum monitoring protocol will attributes for which monitoring is mandatory. take to achieve. Then determine whether sufficient Following this initial assessment, the full study resources (especially suitably qualified staff) will be requirements should be assessed after establishing consistently available when required. the optimum methods. Monitoring costs should be based on the most cost-effective method that meets the objectives for monitoring each attribute and 2.4.2 Are personnel sufficiently trained the required standards of precision and accuracy, and experienced? etc., as described in Section 2.2. The assessment should take a long-term view of Consideration of staff resources available for mon- the requirements for monitoring and available itoring must include an assessment of the expertise resources, including likely year-to-year variations and experience necessary for the chosen methodol- in monitoring needs and budgets. A poor monitor- ogy and, if necessary, the acquisition of a licence (see ing design is one in which the monitoring effort below). As a minimum, it is essential to be familiar changes from year to year, or in which monitor- with the habitat, study species and survey methods ing is dropped in one year because of a lack of required. The correct identification of target species resources. This variability introduces yet another may require specialist personnel even if the meth- confounding factor, which will cloud the interpre- ods themselves are straightforward. Alternatively, tation of the results obtained. the method itself (e.g. electrofishing or bird ringing) If the resources needed for a full monitoring may require specialist training and/or licensing. If programme exceed those available, the two the monitoring involves several people they should options are: (i) to seek more funds; or (ii) to trim all be trained to a minimum standard and recording the monitoring programme in the least damaging techniques should be standardised; this can be done way, e.g. by monitoring less frequently or by as part of a preliminary study. 46 2 PLANNING A PROGRAMME

Monitoring work may well be contracted out to valuable in determining what equipment is neces- staff from outside agencies. These people must also sary. Going into the field and realising that a piece be suitably trained and experienced to carry out the of equipment is required halfway through getting to work to a sufficient standard. the site, or once on it, is disorganised and may waste considerable time and money. On the other hand 2.4.3 Are licences required, and are there going into the field laden with excessive gear will animal welfare issues to consider? slow you down and is unnecessary.

An important consideration when surveying and monitoring species (particularly for rare species) 2.4.5 Are there health and safety issues is that staff may need to hold a licence. For exam- to consider? ple, under the 1981 Wildlife & Countryside Act, Fieldwork can be a dangerous activity and so licences are required from the relevant government before carrying out any such work, a careful risk department or agency to enter bat roosts, trap pro- assessment should be undertaken to identify tected species such as Great Crested Newts, and potential risks and minimise these by ensuring survey many rare breeding birds. Invasive mark– that safety precautions are strictly followed. recapture methods such as toe-clipping for amphi- Recommended precautions for general fieldwork bians may require a Home Office licence under the are given in Box 2.11, but these are not intended Animals (Scientific Procedure) Act 1986. It is there- to be comprehensive. Fieldwork involving the fore necessary before a method is selected and used use of specialist equipment or activities, such as that the need for a licence be investigated. If one is diving, will certainly need additional safety meas- required, staff should obtain the licence and any ures and may well require staff to be suitably necessary training in advance. qualified. Animal welfare issues may need to be considered: certain survey and monitoring techniques may have unacceptable effects on the animals being surveyed, 2.5 DATA RECORDING AND STORAGE or on other groups (for example, small mammals 2.5.1 How will data be recorded may be killed in invertebrate or amphibian pitfall in the field? traps). Apart from the obvious point that humans are morally obliged not to cause unnecessary suffer- Once the sampling protocol has been defined, ing to wildlife in the cause of surveying, there are the field data sheets can be designed. Specially other reasons for considering animal welfare. Many designed forms encourage consistency and reduce scientific journals such as the Journal of Zoology are unnecessary writing. Where lots of data are being now asking authors and referees specifically to recorded relatively quickly it may be advantageous address whether animal welfare issues have been to type the data directly into a hand-held datalog- taken into consideration. In addition, public (and ger. A database structure should be written, which political) support for monitoring activities may be prompts the observer to enter the appropriate affected by the impact of survey methods on wildlife record. The advantage of this method is that a and the environment in general. large dataset can be downloaded directly to a computer. 2.4.4 Is specialist equipment required Some remote sampling in which continuous and available? recording of environmental variables is required as part of the habitat condition assessment can All equipment needed for the monitoring study also be achieved with automatic dataloggers. It is should be made available for its duration so that unlikely that automatic datalogging will be essen- standardised methods are employed. A scoping exer- tial or cost-effective for the majority of methods of cise prior to starting the formal monitoring may be assessing habitat condition. 2.4 Reviewing the programme 47

Box 2.11 General health and safety considera- items such as flares, electronic devices and air/- or tions for working in the field gas-pressured alarms should be considered. * The International Alpine Distress Signal is six long * Before undertaking monitoring, survey work, etc., whistle blasts or torch flashes in succession, discuss the proposed activity and terrain with your repeated at 1 min intervals. The reply is three long line manager and others with relevant knowledge whistle blasts or torch flashes repeated at 1 min and experience. This will help in deciding the intervals. relevance of the items below and those elsewhere in * Always carry a first aid kit and know how to use it. this Handbook. Emergency first aid training is available for those * Lone working procedures should be followed. The not in possession of full certificates. minimum requirements, whether alone or as a * Inoculation against tetanus is strongly party, are that you leave details of your itinerary recommended for all staff engaged in fieldwork. with a responsible person; you make arrangements * Staff receiving special medical treatment, such as to contact a responsible person at least every eight a course of injections, or suffering from medical hours and at the end of the working day; and you conditions, such as diabetes, allergies, rare blood ensure that your contact knows what to do if you fail groups, etc., are reminded of the advisability of to make scheduled contact. carrying a card or some other indication of special * Always have suitable clothing for the activity, medical requirements. terrain and weather conditions. Principles of good * Where applicable, sufficient additional medicines, clothing concern insulation, and protection from etc., should also be carried on field trips to ensure precipitation and wind. Although it should be that no medical complications arise owing to lack of recognised that survival in exposed winter treatment. In an emergency the carrying of such mountain environments can be extremely difficult items can save a lot of time and perhaps save without improvising an effective shelter, a fair test your life. of your clothing and equipment is the answer to the * Staff visiting hazardous areas should inform those question: could I survive, be it very uncomfortably, based at the location of any special medical if I were immobilised for 24 hours? High-visibility condition, e.g. diabetes. This, in the event of an clothing is desirable in many situations, both to accident or the person becoming lost, is of great prevent accidental injury and, more importantly, to value to the rescue services. If a party is well be located in an emergency. Boots provide equipped and it is overdue, no great concern may be protection and grip. In general, choose the lightest shown for several hours. However, if a member of pair that will do the job: the requirement for a the group requires regular treatment, a search may rigid-soled heavier boot increases if you will be be speeded up; for example, instead of a preliminary travelling in steep, rocky and winter terrain. foot search being undertaken, a helicopter could be * Carry a map and compass. Know how to use the called for immediately. compass to take a bearing, set a course and walk * If you are new to an area, ask the area staff about any on a compass bearing. hazards. * Consider whether a survival bag might be necessary * Do not fail to inform visiting members of staff of any in remote and/or upland or/mountainous situations. dangers in the area they intend to work in. Spare blankets are not recommended. * Staff about to embark on a rigorous period of * Take spare warm clothing. fieldwork, especially after a period of relative * Have with you some high-sustenance food such as inactivity, are reminded that some attention given sweets, chocolate, glucose tablets or biscuits. to physical fitness beforehand can make the job * Always carry some means of raising alarm. more enjoyable as well as being a positive A whistle and torch are essential items and other contribution to safety. 48 2 PLANNING A PROGRAMME

* Always move carefully over rough, rocky or * Take care to avoid hazardous substances such as vegetation-covered ground, avoiding any loose herbicides and pesticides. boulders, etc. Care should be taken on wet ground * Exercise extreme caution in areas of landfill, tips such as bogs, mud or fens. and spoil heaps, which could be unstable, * Never run down scree slopes or steep hills, and take especially in wet weather. Look out for weakness care not to dislodge loose rocks or other objects. resulting from underground combustion and for * Before setting out on a field trip check the local any toxic substance, including gas, that may be weather forecast. This could save a wasted journey present. or prevent you or your party encountering adverse * Identify areas where game shooting may take place. weather conditions, which could put your lives Find out when and where this is taking place and at risk. Be aware of weather conditions around take appropriate measures, including wearing you while outside, for example distant storms, high-visibility clothing. which may change direction and come towards you. * Note that care of general health while doing * Avoid machinery, whether in use or not. fieldwork is essential, as exhaustion can lead to * Enquire about and avoid potentially dangerous careless mistakes and lower resistance to diseases. animals. Source: extract from SNH Health and Safety Manual.

Back-ups of all data files should be kept on disks 2.5.2 How will the data be stored? or different computers, preferably in different build- Storage directly on to a computer or interface in the ings. Logs of existing data, with descriptive details field saves time but machines are prone to breaking and locations, should be kept for all sites. Hard copies down and may be expensive to back up. Work out a of all data should also be kept. Although much of this standard procedure for storing the data with under- is common sense and generally accepted good prac- standable file names if on a computer, or filed by tice, it is surprisingly often ignored. project or site name if in map form. Maps can also be scanned in and stored on computer hard drives, or 2.5.3 Who will hold and manage the data? CD-ROM as a security measure. Collecting data in the field is laborious, expensive and difficult to It is usually valuable to make one person respon- repeat, so good computer and digital storage of sible for databases and for managing them, i.e. information is sensible. The information storage updating, upgrading, producing reports from them, needs to take account of software and hardware and so forth. Some databases, such as Microsoft 1 obsolescence: data will need to be retrieved several Access , allow the manager to design standard decades from now. Consider also the requirements reporting forms and outputs, which anyone of data analysis software, which may only read data responsible for a site, or an aspect of the habitat, organised in a particular format. or, for example, policy factors affecting it can use Databases, such as Microsoft Access1,enableeasy to produce standard outputs. This limits individual manipulation of data for various methods of analysis. bias in interpretation and presentation. Such data- They are also useful for holding textual data, such as bases can be made read-only prior to entering a descriptions of sites, changes to vegetation, etc., password, which prevents data from being chan- which are non-numeric. However, spreadsheets ged by unauthorised personnel. However, the data offer better capacity for analysing numerical data should be made available for use throughout an and are easier to use, especially for beginners. If organisation and beyond, depending on commer- the data are entered into a spreadsheet they can cial confidentiality or other constraints, so it is usually be imported into a variety of statistical important to make sure that people know of its packages for analysis. existence and the name of the contact person or 2.6 Data analysis and interpretation 49

data manager so that they can gain access to it analysis used to demonstrate that such a change is should they need to. occurring.

2.5.4 Will the data be integrated with other datasets and if so, how? 2.6 DATA ANALYSIS, INTERPRETATION AND REVIEW If data are held in a program suite, such as that containing Microsoft Access1 or Excel1, they can 2.6.1 Who will carry out the analysis be integrated with data collected by someone else and when? quite easily. If stored on a compartment basis (i.e. Data should be collected, stored and filed in such a a management compartment for a site, as used in way that anyone with the required skills should be the standardised Countryside Management System able to analyse it. It is always important to describe (CMS)), integration with species-based data can through written SOPs: be achieved in relation to compartment-based * how and when the data were collected; management projects. This is an essential part * what problems and/or issues arose and how they of project planning as part of the Conservation might affect the interpretation of the data; Management Plan for a site. For example, data * the sampling design together with clearly labelled for a site may be held on a compartment-by- maps of site and stratum boundaries; compartment basis, corresponding to manage- * the notation and codes for species; and ment units listed as projects in the Conservation * the format, location and file names of computer Management Plan for the site. As such, both textual datasets or hard copies. and numerical data can be held in the same file. In addition, there could be a number of fields that In addition it is important that monitoring pro- describe other data held for the site, which have grammes should identify the resources required been collected elsewhere. This information should for data analysis and the writing of reports, who consist of type of information, e.g. habitat survey should be responsible for this, and when it should data, year(s), compartments, whether material be undertaken. Often this is overlooked and data has been published, and perhaps compatibility accumulate that are never properly analysed and of these data with those held in the monitoring presented. database. Links to research projects could similarly The data analysis should be carried out by some- be made. one with a good understanding of statistics and, in Spatially referenced data can be integrated into particular, an awareness of when particular analy- a geographical information system (GIS) such as tical methods are appropriate and the potential 1 ArcGIS . GIS systems are becoming increasingly pitfalls associated with their use. Misapplied tests widely used; they can add value to the analysis of or poorly presented data can lead to misinterpreta- spatially referenced data by enabling other datasets tion and poor management decisions. held for the site to be overlaid and compared (for example, data on soil type can be overlaid and 2.6.2 What are the steps in analysing correlated with data on vegetation communities). data? The examination of spatial trends in the range of a species can also be carried out with a GIS pro- A comprehensive account of statistical methods for gram. In addition, the ability to generate visual data analysis would take up most of this book and representations of your data can greatly enhance there are already numerous books devoted to this the ease with which it can be interpreted and (see the suggested references at the end of this understood. For example, a map of a site showing section). The sections that follow simply outline changes in the extent of a particular habitat type the approach to take with some common methods will lend weight to a description of the statistical and the pitfalls to look out for. 50 2 PLANNING A PROGRAMME

Further information on statistical techniques Sokal & Rohlf (1996) Young & Young (1998) BOOKS Zar (1984) See References for full details. Bailey (1981) INTERNET SITES Dytham (2003) www.ltsn.gla.ac.uk (a good starting point for online Fowler et al. (1998) statistical resources) Kent & Coker (1992) www.anu.edu.au/nceph/surfstat/surfstat-home/surf- Krebs (1999) stat.html (an online text in introductory statistics) Manly (1997) www.stats.gla.ac.uk/steps/glossary/index.html Mead et al.(1993) (detailed statistical glossary)

Three distinct stages in the analysis of survey data values or how different measurements are and monitoring data can be identified, as follows. related. These can affect how the data are then analysed and interpreted. For example, are the 1. Description and presentation of data measurements of vegetation height normally dis- 2. Making inferences about the site or population tributed or are there distinct vegetation types on 3. Interpretation and presentation of findings the site, resulting in a more complex distribution? Each of these stages is discussed in turn and Alternatively, is there an association between the together they provide a framework for ensuring abundance of one species and another? Spatial that appropriate methods are used and that the patterns are only likely to be revealed by map- findings are communicated successfully. ping; if these can be combined with other local datasets, additional relationships may become 2.6.3 Description and presentation of data apparent. * The main features of the data are poorly presented. The importance of exploring and summarising Interpretation and presentation of findings is cov- data, before launching into anything more com- ered in Section 2.6.5, but it is worth noting here plex, cannot be overstated. The dangers of missing that graphical displays are often the most powerful out this step include the following. way of communicating what the data show and it is worth taking time to find the best way of * Inappropriate analyses are used or the assump- achieving this. tions for these do not hold. * Peculiar or erroneous data values, which may exert The best way of summarising and displaying data a strong influence on how the data are interpreted, depends on the following. are not detected. These ‘outliers’ may be caused by measurement or recording error or mistakes dur- * The type of data available. Whether the data are ing data entry. Alternatively, they may be valid nominal, ordinal or quantitative will affect what measurements that just happen to be rather descriptive statistics and displays make sense. extreme. In the latter case, it may be decided to * The amount of data available. With a sample size include these values in the analysis, but it is impor- of 10 it will not be possible to say much about the tant to be aware of the extent to which conclusions underlying probability distribution the data fol- are influenced by one or two outliers. low, but with 100, a histogram, or similar, should * Clear patterns and other features of the data are be informative. missed. Graphical and tabular display of data can * The objectives for the analysis. If interest centres reveal important aspects of the distribution of on whether a measurement has changed over 2.6 Data analysis and interpretation 51

time, examination of changes in some summary In addition, the mean is sensitive to outliers, so measure, such as the sample mean, is appropriate. if, for example, the variable has a distribution If relationships between measures are of interest a where most of the values are fairly small but a scatterplot or cross-tabulation can be helpful. few are fairly large, changes in the mean over time will be very sensitive to the values from a Nominal and ordinal data small number of sampling units. In this case the Nominal and ordinal data are summarised by cal- median, which does not suffer from this problem, culating the proportion of sampling units that fall may be a better summary statistic. within each category: for example, the proportion Changes between surveys can be viewed by for which the species was present or the proportion plotting summary measures, such as means, as of quadrats in a particular vegetation height class. a time series. The addition of error bars to such Such data can be displayed in bar charts, and shifts charts, which may show confidence intervals or in the distribution of values in each class may be standard errors, can illustrate changes in the vari- apparent by plotting the results of two or more ables’ variability. Displaying the individual values, surveys together. For ordinal data this might take perhaps as a series of box plots or dot plots, can the form of a series of stacked bar charts. reveal changes in the distribution as well as in the Relations between two such categorical variables mean or median. can be investigated through cross-tabulation or bar Scatter plots can help explore relations between charts with one variable grouped within the other. quantitative variables; and the extent of linear association can be measured by calculating correlation Quantitative data coefficients. A much greater range of possibilities is available for quantitative variables. If data from sufficient sampling units are available, the distribution of 2.6.4 Making inferences about the site each variable can be investigated by using graphs or population such as histograms, box plots and dot plots. The In general, we want to use data collected from a latter two are particularly useful for revealing out- sample of a population to be able to say something liers. Histograms, box plots and normal-probability about the population as a whole. That is, we want plots can reveal peculiarities in the shape of the to make an inference about the population. For distribution (e.g. skewness) and indicate whether example: has sphagnum cover changed and by a data transformation (Section 2.6.4) might be how much; has the abundance of species x required prior to using hypothesis tests, as for declined; or is the breeding success rate of species example in Box 2.12. y at a satisfactory level? Descriptive statistics such as the mean and stan- Thus the reason for analysing survey and mon- dard deviation of the dataset (Box 2.4) can be useful itoring data will usually be either: summaries, providing a central, middle value and a measure of variability, at least for data that are not * to compare data from a single sampling occasion too non-normal. Formulae for calculating mean and against a pre-defined limit (for example, the limit standard deviations for data collected by using stra- below which a population should not fall); or tified or two-stage sampling are provided in Box 2.13. * to compare data from two or more sampling The mean will not be a very informative sum- occasions to determine what changes have mary if the variable has a distribution with a cluster occurred. of low values and another of high values, for example. In this case the distribution is said to be bimo- Both of these objectives will usually involve the use dal and this could happen if the site covers two very of hypothesis tests (Box 2.9) and or confidence different habitats or the population contains intervals (Box 2.8). Hypothesis tests enable us to distinct sub-populations. say, for example, whether there is evidence that 52 2 PLANNING A PROGRAMME

Box 2.12 Histograms, box plots and normal (B) BOX PLOT probability plots The box (Figure B2.12b) extends to the lower and upper quartiles, with a line indicating the median. The lines outwith the box extend 1.5 times the width of the The data presented are percentage cover interquartile range or to the lowest or highest value. measurements for Heather Calluna vulgaris from 120 Values outside this range are indicated as outliers. quadrats. For normally distributed data we would expect a fairly symmetrical plot around the median. This is not the (A) HISTOGRAM case here; a number of outliers are indicated. The area of each bar represents the proportion of measurements falling in the interval shown by the (C) NORMAL PROBABILITY PLOT horizontal axis. In most cases, where all bars have the This plots the cumulative proportion of data values same width, the height of each bar is the number of against that expected for normally distributed data measurements in that interval. In this example (Figure B2.12c). Departures from the straight line (Figure B2.12a) the distribution is clearly skewed indicate departures from normality. Again the data are and a transformation is likely to be needed prior to clearly non-normal and transformation is required if analysis. parametric methods are to be applied.

(a) (b) (c)

100 1.00 30 80 0.75 60 20 40 0.50

count % cover 20 10 0.25 expected cum. prob. 0

0 –20 0.00 0 1020304050607080 0.00 0.25 0.50 0.75 1.00 % cover observed cum. prob.

Figure B2.12. Examples of (a) histogram, (b) box plot and (c) normal probability plot. See text for details. change in some population measure has taken Statistical methods will usually make some place. However, this of itself may be of limited assumptions about the distribution of the data, or interest. Often we know that some change is likely more specifically about the test statistic. This is the because populations and habitats are naturally summary measure for which we want to calculate dynamic. Rather, we want to know how much confidence intervals or form hypotheses. Most change there has been so that the ecological sig- commonly this will be the mean value or the nificance of this change can be evaluated. This is proportion falling in a particular class. This sum- where confidence intervals, or similar, are useful mary measure will also have a sampling distribu- in providing a range in which we have some con- tion, because different samples will result in a fidence that it contains the true level of change. different value for the summary measure, but its See Eberhardt (2003) for a discussion of this and distribution may be very different from that of the other issues surrounding hypothesis testing. original data. 2.6 Data analysis and interpretation 53

Box 2.13 Estimating means and standard way (Box 2.8). The number of degrees of freedom (df) deviations for stratified and two-stage sampling for calculating the required t-statistic is P 2 2 STRATIFIED SAMPLING P ð ghsh Þ df ¼ 2 4 ; For each stratum (h) and for a measurement x, we ðgh sh =ðnh 1ÞÞ define: n ¼ total number of units (e.g. quadrats, where gh¼ Nh(Nh nh)/nh. individuals, etc.) sampled in all strata; nh¼ number of units sampled in stratum h; TWO-STAGE SAMPLING N ¼ total number of possible sampling units in h We assume that the same number of minor units are stratum h; sampled within each major unit. If we define the x ¼ mean of x in stratum h; h following: s ¼ standard deviation of x in stratum h. h N ¼ number of major units available for sampling; Then if we calculate n ¼ number of major units sampled; W ¼ stratum weight for stratum h ¼ N /N where h P h total U ¼ number of minor units within each major unit; N ¼ N , total h u ¼ number of minor units sampled within each the estimate of the overall mean is calculated as major unit; X then the overall mean is estimated as Whxh: x¼ mean over the major units of the minor unit If we define means. Defining fh ¼ nh=Nh 2 sx ¼ variance of the minor unit means; m ¼ mean of the variances within minor units; then the standard error of the overall mean is s the standard error for x is calculated as rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi X sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 2 SEx ¼ Wh sh ð1 fhÞ=nh : n s2 u m SE ¼ 1 x þ 1 s : x N n U un If this mean is approximately normally distributed then we can calculate confidence intervals in the usual

As introduced in Box 2.7, a key result (the Central will require a large sample size before their mean Limit theorem) states, in essence, that as the sample can be regarded as normal. size increases the distribution of the mean of a An outline of the stages of data analysis is variable from a random sample will converge to shown in Figure 2.11. This illustrates that selecting being normally distributed. As many of the stan- an appropriate statistical method depends cru- dard methods in statistical inference assume that cially on the distribution of the test statistic. the test statistic is normally distributed, this result The sections that follow describe the various meth- is of huge significance. It means that, provided ods available. Methods primarily aimed at quanti- the number of samples is sufficiently large, we can tative data are split into three broad classes: assume that the mean of the variable of interest parametric methods, methods based on ranks and is approximately normal. What we mean by suffi- resampling methods. The analysis of category ciently large will depend on the distribution of the data is considered separately. A rather different underlying data. For example, data that exhibit a approach, Bayesian inference, is also briefly very skewed or otherwise non-normal distribution described. 54 2 PLANNING A PROGRAMME

Summarise and Correct data errors, if display variable necessary

Determine approximate distribution of test statistic

Test statistic non-normal, Test statistic is roughly e.g. skewed Distribution unknown (e.g. normally distributed because data too few)

Apply tests and/or Apply Use distribution-specific, calculate confidence Successful transformation Not non-parametric or intervals for normal successful resampling method data

Interpret and present findings

Figure 2.11. Flow diagram outlining the steps involved in data analysis, for each variable of interest.

The choice of test also depends on whether analysis (see p. 61) or to use a non-parametric or data for more than one survey are paired or resampling method. unpaired. Paired data arise from permanent plots For quantitative data that are not very skewed in in which the measurement taken in a given plot distribution, 25–30 samples are usually sufficient during one survey can be compared directly with for assuming that the sample mean is approxi- the measurement taken during another survey. mately normal. If the distribution is very skewed, If a new sample is selected for each survey the for example because of a large number of zero two samples cannot be paired in this way. Tests counts, rather more samples are needed. An alter- for paired samples are usually more power- native is outlined on p. 60. ful than those for unpaired, or independent, Table 2.3 lists some parametric tests to consider samples. for different situations. Although these cannot be detailed here, accounts are readily found in most statistical textbooks or in the documentation for Parametric methods statistical software. Parametric methods assume that the test statistic follows a particular distribution, usually the normal distribution. If the underlying data are very T-tests non-normal and/or sample sizes are small it will The t-test compares the mean values from two be necessary either to transform the data prior to groups and is by far the most commonly applied 2.6 Data analysis and interpretation 55

Table 2.3. Some parametric statistical tests appropriate for analysing survey and monitoring data

Number of Paired or unpaired Some tests samples data to consider

One n/a One-sample t-test Two Paired Paired t-test Unpaired Independent sample t-test More than two Paired Repeated measures analysis of variance Route regression Generalised additive models Unpaired Analysis of variance Linear or polynomial regression Generalised additive models Time-series analysis test. It is worth summarising a few of the consid- When data from more than two surveys are avail- erations needed for using it appropriately. able, the class of methods called Analysis of Variance (ANOVA) can be used to look for differ- * T-tests are reasonably robust to minor departures ences across the surveys. Repeated measures from the assumption that the data are normally ANOVA is used for data from permanent distributed. plots. ANOVA can be used to look for trends, * The independent sample t-test would be used to but as more data become available the methods compare results from two surveys using non-perfor detecting trends outlined on p. 59 can be manent plots. This test assumes that the data from considered. the two samples have similar variances. Although the test is also robust to small departures from Methods based on ranks this assumption, provided the two samples are of When there are insufficient data to be able to apply similar size, the variances should be compared. parametric methods with confidence, or when Most statistical packages include a test for com- there are other concerns over the applicability paring variances. Some packages will provide a of such methods, then non-parametric methods modified t-test to be used when the variances are based on ranking the data provide an alternative. different. If the measurement of interest is ordinal then * A paired t-test should be used for data from methods based on ranks are often appropriate. In permanent plots and will be more powerful than general, such non-parametric methods are less an independent sample test provided there is powerful than the parametric equivalent, so the some correlation between the data from the two applicability of parametric or resampling methods surveys. should be considered first. * Tests can be one-sided or two-sided. Use two-sided The two most commonly used tests are the tests unless a one-sided hypothesis test has been Mann–Whitney rank-sum test and the equivalent specified in advance of the survey or there is an a for paired data, the Wilcoxon signed rank test. priori reason for change being in only one These and some other rank-based tests are listed direction. in Table 2.4. 56 2 PLANNING A PROGRAMME

Table 2.4. Some rank-based tests appropriate for analysing survey and monitoring data

Number of Paired or unpaired Some tests to samples data consider

One n/a Sign test Wilcoxon test Two Paired Wilcoxon signed rank test Sign test Unpaired Mann–Whitney test More than two Paired Friedman test Unpaired Kruskal–Wallis test

Mann–Whitney test positive differences are calculated separately. The Sometimes called the Mann–Whitney U-test or test statistic is the smaller of these two sums; parti- Wilcoxon’s rank-sum test, this compares the distri- cularly small or large values will indicate that one butions of two independent samples. Unlike the or other group tends to take larger values than the t-test, which specifically compares the mean from other. As for the Mann–Whitney test, the Wilcoxon the two samples, the Mann–Whitney test simply test is usually performed by using statistical soft- tests whether the two distributions are identical or ware, which will also take account of ties. whether one tends to have larger values than the other. Resampling methods The two samples are combined and numbered The advent of fast computers has made possible according to their rank, from smallest to largest. the development of another class of methods The sum of these ranks for one of the samples is that derive distributional properties of summary then selected as the test statistic with particularly statistics by generating large numbers of new sam- small or large values indicating that the selected ples from the original data. Primarily used for quan- sample comes from a distribution that is shifted to titative data, such methods enable the calculation of the left or right of the other one. Whether the test confidence intervals and the use of hypothesis tests provides evidence for rejecting the hypothesis that without making assumptions about the distribution the groups have the same distribution is deter- of the data and are usually more powerful than non- mined from statistical tables or, more commonly, parametric methods that make use of data rankings by the software performing the test. Such software rather than the data values themselves. Two parti- will also make allowance for any ties in the cular methods in common use are the bootstrap and rankings. randomisation tests. A good reference for further detail is Manly (1997). Wilcoxon’s signed rank test For paired data this tests whether one group tends Bootstrapping to have larger, or smaller, values than the other. The idea behind bootstrapping is that if it is diffi- For each pair the difference in values is calculated cult to make distributional assumptions about a and then these differences are ranked from smal- summary measure then the data themselves are lest to largest without regard for sign. The sum of the best guide to what that distribution is. To the ranks for the negative differences and for the approximate what would happen if new samples 2.6 Data analysis and interpretation 57

were selected from the population under study, reasonable to suppose that the observed difference bootstrapping involves selecting new samples will not be particularly large when compared with (resamples) from the sample data themselves. this distribution. The null hypothesis is rejected if Such resamples are selected with replacement, less than 2.5% of the randomised differences are that is each sample value can occur more than greater than the observed difference (two-sided once in each resample. Large numbers of resamples test). In practice it is usually impracticable to gener- (typically around 1000) are drawn and for each one ate all possible allocations and so a large random a new estimate of the summary measure is calcu- sample of allocations is more commonly used. lated. In its simplest form a bootstrap 95% confi- Randomisation tests are used for detecting dence interval is then estimated by reordering the change and trends where the data are extremely resampled estimates from smallest to largest and non-normal. They are also used in multivariate ana- selecting the 2.5 and 97.5 percentile values as the lysis, for example to test the significance of relation- interval limits. This simple form of the bootstrap is ships between species and environmental variables. relatively easy to implement in a spreadsheet, although many general-purpose statistics packages Categorical data provide a range of bootstrapping methods. For presence–absence data or where interest cen- Bootstrapping can also be used for hypothesis tres on the proportion of samples falling into a testing but the above method can be adapted if particular category, parametric methods can some- interest centres on the likelihood of change in a times be applied but rather more samples are likely mean value between two surveys. If permanent to be needed than for quantitative data. Table 2.5, plots were used then simply calculate the change adapted from Cochran (1977), gives minimum sam- for each plot and bootstrap these change values ple sizes for a confidence interval based on a nor- using the mean as the summary measure. If the mal approximation to be applicable. resulting confidence interval does not extend Calculation of confidence intervals is outlined in across zero we can be reasonably confident that Box 2.8. For proportions, the formula to use for the there has been a change. For non-permanent plots standard error is rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi the two samples have to be bootstrapped sepa- p^ð1 p^Þ n rately. Each resample from the two samples is SE ¼ 1 ; n 1 N paired and the difference in means calculated. These can then be used to estimate a confidence where pˆ is the sample estimate of the proportion interval for the difference in means. of interest. Bootstrapping has gained in popularity in recent years and will often be recommended by journal referees if there is any doubt over the distribution Table 2.5. Smallest sample sizes needed to use a normal for quantitative data. approximation when calculating confidence intervals for proportions Randomisation tests Another class of methods that are primarily used for Proportion of plots Required testing differences between two or more groups are in category of interest sample size randomisation tests. This is essentially a resampling method without replacement where the observed 0.5 30 difference between groups is compared with what 0.4 50 would be obtained by randomly allocating the data 0.3 80 to the groups. In theory all possible allocations 0.2 200 could be considered and a distribution of possible 0.1 600 differences generated. Under a null hypothesis that 0.05 1400 there is no difference between the groups it seems 58 2 PLANNING A PROGRAMME

Table 2.6. Some tests appropriate for analysing categorical data.

Number of Paired or unpaired Some tests samples data to consider

One a n/a Exact binomial confidence interval Normal approximation Binomial test Two b Paired McNemar’s test Unpaired Chi-squared test Fisher’s exact test Normal approximation More than two Paired Cochran Q test Unpaired Chi-squared test

a For ordinal data the ranking methods described in Methods based on ranks (p. 56) may be appropriate. b Note that the parametric regression and modelling methods may also be appropriate.

Table 2.7. Example data for chi-squared test

No of quadrats Expected number Total number with species of quadrats with of quadrats Year present (O) species (E) taken

1402550 2302550 3 50 50 100 4 30 50 100 Total 150 150 300

To compare two samples to see, for example, plots containing a species has changed. The data whether a change has taken place in the propor- can be presented in the form of a table (Table 2.7) tion of the site falling within a category interest, whose cells show the number of sample plots for the most commonly used tests are chi-squared (2) which the species was present and absent for each tests and, for paired data, McNemar’s test. These survey. In this example new plots have been used and some other tests for categorical data are listed for each survey. in Table 2.6. To test the null hypothesis that the proportion of quadrats in which a species is present is the same Chi-squared tests in each year, we compare the observed data with These are a class of tests for examining hypo- that which would be expected if no change had theses for category data. For example, suppose pre- taken place. The chi-squared test is then used to sence–absence data are available from four surveys see whether the observed and expected values are and interest centres on whether the proportion of sufficiently different for it to be unlikely that no 2.6 Data analysis and interpretation 59

change has occurred. The chi-squared statistic is The chief advantages in this approach are that calculated from the equation: * all available information is made use of; X 2 * the interpretation of credible intervals and ðO E Þ 2 ¼ i i ; Bayesian hypothesis tests is more straightforward E i than for classical methods; and * where Oi is the observed frequency of the species in recent developments mean that complex models, question in a given year i and Ei is the expected including spatial structure, can be analysed. frequency if the species is not changing. The disadvantage, for some, is that specification of Expected values are calculated by: the prior distribution is inevitably partly subjective. However the effect the prior has on the final Eðone yearÞ estimates can be controlled: vague prior distribu- total quadrats in which species present tion will have relatively little effect and the more ¼ total number of quadrats overall data that are collected, the greater will be the rela- total quadrats taken in that year: tive influence of the data compared to the prior. The basic principles behind Bayesian inference This value is compared with values of 2 from are straightforward, but its implementation can statistical tables. We need the degrees of freedom, quickly become complicated. Although fast com- which is given by the number of years minus 1; in puters have made complex Bayesian models feasi- this case 3. ble, keeping things relatively simple depends on careful choice of prior and data distributions. The availability of software tools, such as Bayesian inference WinBUGS (www.mrc-bsu.cam.ac.uk/bugs), have Bayesian inference differs from the classical methods raised the profile and popularity of Bayesian meth- described so far in that it makes use of prior infor- ods. For an introduction see Lee (1987) or Marin mation about the population measure of interest. et al.(2003). Rather than treating this measure as being fixed, Bayesian methods give it a probability distribution, Detecting trends which is determined by the nature of the measure When a monitoring scheme has been running for and the extent of prior knowledge. This prior distri- some years the question is likely to arise as to bution is then combined with information provided whether there are discernible trends in the size of by the survey data, using Bayes’ theorem, to derive a a population of interest or in the extent of a habi- posterior distribution for the measure. This posterior tat, for example. It is unlikely to be worth investi- distribution tells us what we know about the popu- gating this until five or more repeat surveys have lation measure given the data and our prior knowl- been carried out. edge and can be used to provide an estimate of the The first step, as always, is to plot the data as measure and a Bayesian equivalent of the confi- a time series, i.e. the summary measure on the dence interval, often called the credible interval. vertical axis against time on the horizontal axis. Prior information comes from expert knowl- Are any trends apparent? Are they linear or more edge about the site or population, from previous complex? Are cyclical patterns apparent? surveys and/or from surveys on similar sites or Testing for trends is most straightforward if the species. The prior distribution is defined according measure used comes from complete counts rather to the quality of this information, so, for example, a than from sample surveys and the trend appears to normally distributed prior will have a large vari- be reasonably linear. The most common approach ance if the prior information is rather vague and is to then fit a regression line through the values, uncertain, and a small variance if the population with time as the explanatory variable. The gradient measure is fairly well known. in the regression line is then tested to see whether 60 2 PLANNING A PROGRAMME

it is significantly different from zero. If so, a trend concerned with modelling, studying autocorrela- is indicated. tion structure, detecting cyclical behaviour and There is one complication with this method. forecasting. A good introduction is provided by Standard regression analysis assumes that Chatfield (1996). the values of the measurement variable are independent of each other. In effect this means they are Some particular issues uncorrelated. However, the results of successive The following sections provide a discussion of two surveys are very commonly correlated because common scenarios that arise. the size of a population or habitat in Year 1 will have an effect on its size in Year 2. The effect of this Data with many zeros autocorrelation is that the statistical significance of This situation frequently arises when the species of the gradient will be overestimated. This is unlikely interest is often absent from sample plots. to be an issue if the gradient is very highly signifi- Measures such as counts of individuals or percen- cant, but in some cases positively autocorrelated tage cover often exhibit a preponderance of zeros. data can give the appearance of a trend. For example, Figure 2.12 shows the distribution There is no easy way of getting around this proof counts of occupied Manx Shearwater Puffinus blem. One approach is to use bootstrapping of the puffinus burrows from a sample of 20 m2 plots. regression model parameters. An alternative is to Because this distribution is so skewed the distribu- include a term in the regression for the previous tion of any summary statistic is also likely to be year’s count, to remove some of the autocorrela- skewed, despite the relatively large sample size. tion effect. However, the correct method to use For this example, either of two approaches will will depend on the nature of the autocorrelation; probably work well. a fairly large number of surveys are likely to be needed before it can be studied in detail. Perhaps 1. Given the large sample size it is reasonable to the simplest way forward is to consider whether assume that the mean count per plot will approxi- autocorrelation is likely given the ecology of the mately follow a log-normal distribution (a skewed species or habitat under study and, if so, to interpret borderline trends with caution. If the trend is clearly non-linear, and sufficient data are available, more complex models such as polynomial regression or generalised additive 300 models can be fitted. Where the survey data comprise sample measurements then this should be allowed for in the 200 trend analysis. The simplest way is to include each measurement in the model so that uncertainty in the true population mean is taken into account. Number of plots One alternative for permanent plots is to model 100 each plot separately and combine the resulting trend estimates to get a picture of the overall trend. This is the approach taken by route regression (Geissler and Sauer, 1990) which is very widely 0 012345678910111213141516 used in North America. Generalised additive mod- Number of occupied burrows els have been proposed as a more flexible alternative (see, for example, Fewster et al., 2000). Figure 2.12. Bar chart showing the number of Long time series are fairly uncommon in ecology occupied Manx Shearwater burrows. See text for but there is a substantial literature for methods futher details. 2.6 Data analysis and interpretation 61

distribution whose logarithm would be normally (as it does for the Poisson distribution, for example). distributed). Confidence intervals for the mean can Most parametric tests assume that the data are nor- then be calculated by using the methods described mally distributed, which also implies that the var- in the next section. Change in this mean could iance is independent of the mean. Applying a probably be assumed to be approximately nor- transformation to the data can often help to rectify mally distributed. these problems by ‘stabilising’ the variance and 2. To avoid any distributional assumptions, boot- making the distribution more symmetrical. strapping of the counts can be used to generate If the distribution of the transformed variable is confidence intervals, etc. In this particular exam- not exactly normal, this is probably not critical, ple this was complicated by the fact that a strati- provided that the sample size is moderately large. fied random sampling scheme was used and so Often it is more important to choose a transforma- each stratum had to be resampled separately. tion that stabilises the variance. However, transfor- Results were very similar to those obtained by mations may not work for data with a sophisticated using the first approach. or complex structure. The effect of different transformations should be examined to see which gives the best approxi- Small sample sizes mation to the normal curve. Histograms or normal When sample sizes are small it is likely to be diffi- probability plots can be used for this purpose and cult to determine the distribution of the data with the goodness-of-fit of your data to a normal distri- any confidence. See Figure 2.8 for an example of bution can be tested by using a chi-squared test how the true distribution only emerges as sample (see above, p. 58). size increases. In this situation it may be difficult to Data are usually transformed to make para- justify applying parametric methods. Exceptions metric analysis possible. Any confidence interval, occur where there are theoretical grounds for or similar, obtained through transformed data assuming a particular distribution or there is evi- should be back-transformed into the original dence from other, similar, data. units. This is because an answer expressed in An example of the former is presence–absence terms of angular degree units or square roots will data, where the proportion of plots where the spe- not be intuitively meaningful when considering cies is present may be assumed to follow a binomial estimates of counts of species, etc. Note, however, distribution. In this case the sample size may be too that the back-transformed mean of the trans- small to be able to use a normal approximation formed data will not usually be the same as the but exact confidence intervals can be calculated mean of the untransformed data, and so the back- for binomial data. Many statistical packages can transformed confidence interval will be for a dif- do this, but an Internet search should also reveal ferent summary measure. For example, if the log a number of relevant tools and methods. transformation is used, so that In many cases non-parametric methods may y ¼ log(x )wherex are the original measurements be the only alternative. Resampling may also be i i i then suspect if there are insufficient data to adequately y ¼ log(x )/n ¼ log(product of the x )/n regenerate the underlying distribution. i i ¼ log (geometric mean of the xi). Thus the reversed transformed value of y is the

Is transformation of the data necessary before geometric mean of the xi and reverse transformed statistical analysis? confidence intervals will be for the geometric Many examples of count or frequency data are mean, not the usual arithmetic mean. drawn from distributions that are strongly skewed For the above example there is an alternative (i.e. asymmetrical) and therefore do not nearly approach that provides confidence intervals for approximate to a normal distribution. In addition, the arithmetic mean. If the logarithm of the mean the distribution’s variance may depend on the mean of a measurement, x, is normally distributed, x 62 2 PLANNING A PROGRAMME

itself is said to follow a log-normal distribution. An First, take the square root of each observation. approximate 95% confidence interval for x is Then find the angle in degrees whose sine equals this value. Percentage observations should first x be converted to proportions (divide by 100). The ; xK K arcsin transformation is also useful for cover data that have been converted to proportions. where pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Analysing more than one variable at a time K ¼ exp½1:96 varðlogexÞ More complex statistical analyses, such as multivariate techniques (e.g. principal components ana- and lysis and correspondence analysis) for more than one variable, can be employed to examine com- varðxÞ varðlog xÞ¼log 1 þ : munity composition or the relation between e e x2 community composition and environmental variables. These techniques are mainly exploratory in A transformed distribution may not look vastly nature. There are also various analytical techni- different from the original; the transformation is ques for examining relations between variables, also acting on the variance of the data, which may such as correlation and multiple regression, be more important. For example, the mean of a which might be appropriate for more in-depth Poisson distribution is equal to the variance and analysis of data. These are beyond the scope of the variance thus increases with the mean; the this Handbook but see, for example, Jongman et al. variance is dependent on the mean. In this case a (1995) for more information. square root transformation helps make the variance independent of the mean, allowing tests 2.6.5 Interpretation and presentation based on the normal distribution to be used. of findings Some commonly used transformations are given below. Once the data have been described and analysed, the results have to be interpreted and presented. * log x: This is appropriate for clumped count data in which the variance of the sample is greater than This is often the longest and most difficult part of the mean, or for variables that always take positive the process. Great care should be taken to ensure values such as area (such distributions are often that appropriate conclusions are drawn and that skewed to the left). Each observation is replaced by results are successfully communicated. A study is the logarithm of itself. only as good as the ability of people to understand its findings. After all, the key aim of such presenta- * log (x þ 1): This is appropriate for count data con- tions is to influence the management of a site or taining zeros. Log (x þ 1) is used because log (0) is undefined and hence meaningless. Adding 1 to species and effect change where needed. each observation avoids this problem. p * x: The square root transformation for count Interpreting analyses data, which follows a Poisson distribution (ran- Analyses should be geared towards satisfying the domly distributed), or for regularly distributed objectives for which a survey or monitoring study data, is appropriate when the variance of a sample was set up. Typically this involves determining the is roughly equal to the mean. status of a site or species and, possibly, whether p 1 * arcsin( x): The arcsin (sin or inverse sine) trans- the site or species is in acceptable condition. In formation is appropriate for observations that are addition, it is often desirable to examine whether proportions or percentages, or for frequency mea- existing survey work is adequate and what sures (e.g. presence–absence within sub-quadrats). improvements are needed. For example: 2.6 Data analysis and interpretation 63

* Are sample sizes sufficient to give adequate preci- analysis methods as well as the rationale for these. sion and/or to detect small enough changes? If If necessary, some technical detail may be con- not, then either more effort is required for future signed to an annex. surveys or expectations will have to be reduced. 4. The results of the study. Full data tables, if * Are the measurements adequate and can they required, may be consigned to an annex. be taken with sufficient accuracy? It may, for 5. A discussion of the findings together with the example, become apparent that measurements management implications. are too error-prone for analysis to be reliable. 6. An assessment of the study and its adequacy * Is the sample design adequate or could improve- together with recommendations for future ments to the stratification, for example, be made? improvement.

Some other points to bear in mind when drawing Most results will be presented in the form of tables conclusions from analyses include the following. and/or charts. Charts can provide a very powerful way of conveying information, and appropriate * If the statistical test is non-significant this does not mean that the null hypothesis is true, just displays should be considered wherever possible. that there is insufficient evidence to reject it. However, they are open to misuse. In particular: * If a significance level of 5% is used then bear in * Ensure charts are clearly labelled with units of mind that 1 result in 20 will be significant purely measurement and avoid unnecessary clutter (e.g. by chance. This may not be important for single gridlines and non-essential annotations). Clutter tests, but if many tests are performed there is an can detract from the message a chart is intended increasing likelihood that one will be significant to convey. by chance. This frequently arises in ANOVA when * Avoid exaggerating trends, for example by only multiple comparisons between groups are being displaying the observed range of data. The axes made. Most statistical textbooks will suggest stra- for measurements that can take any positive tegies for dealing with this problem. value should normally start at zero. It is easy to * Where possible, check that a test’s assumptions make a trend look very substantial by starting axes are satisfied. Many tests are fairly insensitive at the minimum observed value. to mild departures from their assumptions, * Include error bars, such as confidence intervals, e.g. t-tests and the assumption that the data are around graph values that are derived from a sam- normally distributed. ple. This avoids giving the false impression that the exact population values are shown and hence Presenting results that any change is a real change. The key to successful presentation is to decide what are the main messages you what to get across Tables should also be clearly labelled and unclut- and how to convey them bearing in mind the tered. For clarity: nature of the audience you are aiming at. The * Data values should be right-justified and sepa- type of audience will affect the level of detail rated for ease of reading. Comma separators can included and the level of technical expertise that be used to make large values clearer. can be assumed. In most cases a survey or monitor- * When the results for statistical tests are presented, ing report would be expected to include the show p-values rather than just whether or not the following. result was significant. Levels for determining sig- 1. The rationale for the study together with any nificance are to some extent arbitrary, so results required ecological background. that do not quite achieve significance may still be 2. A statement of the study objectives. of interest. 3. An account of the methodology used: the sam- * Show the criteria used to determine the signifi- pling design, field methods, measurements and cance or otherwise of tests. 64 2 PLANNING A PROGRAMME

* Confidence intervals for estimates are also often (www.sas.com) and Genstat (www.nag.co.uk) are useful, not only to convey uncertainty but to show all examples that can cope with most of the statisti- the range within which the true value is likely to cal tests and models in common use and rather more lie in relation to a target value, for example. besides. STATA and SPSS are specifically able to analyse data from stratified and other survey 2.6.6 What statistical software is designs. available for the analysis of data? Some resampling methods are available in many general-purpose statistics packages. An example Most spreadsheet programs, such as Microsoft of a dedicated package can be found at www. Excel, have functions for simple statistics and a resample.com. reasonable range of tailor-made analytical routines More specialised software may be required for and graphics. However the range of statistical certain types of ecological data and analyses. analysis that can be carried is usually limited; CANOCO, for example, provides a good range of non-parametric tests, for example, are generally ordination and clustering techniques for multivari- absent. Statistical add-ons for Excel are available ate environmental data (www.canoco.com; ter and these provide an inexpensive way of gaining Braak & Smilauer, 1998). DECORANA is another access to most of the commonly used tests. well-established program for ordination and Examples of these are Berk & Carey (2000), TWINSPAN is widely used for the classification Analyse-it (www. analyse-it.com), and XLStat of species and sites according to similarity (both (www.xlstat.com). available from the Centre for Ecology and However, dedicated statistics programs are best Hydrology in the UK: www.ceh.ac.uk). MVSP is for most statistical analyses, not only for their analy- another popular multivariate analysis package that tical capabilities but for the ease with which they can also enables calculation of a range of diversity be used to present data and check assumptions. indices (www.kovcomp.co.uk/mvsp). Finally, a good These are recommended if a regular requirement online resource with links to many free for statistical analysis can be identified. Systat and commercial software sites can be found at (www.systat.com), Minitab (www.minitab.com), www.statistics.com. SPSS (www.spss.com), STATA (www.stata.com), SAS 3 * Biodiversity evaluation methods

3.1 BIODIVERSITY VALUES AND texts such as Usher (1986), Smith & Theberge EVALUATION PURPOSES (1986), Spellerberg (1991) and Treweek (1999).

In general terms, biodiversity evaluation is the process of measuring the value (ideally quantitatively) 3.2 A FRAMEWORK FOR ECOLOGICAL of biodiversity components, such as the number of EVALUATIONS species present, the population of a species, a habi- Appropriate approaches and criteria for biodiver- tat (usually meaning a vegetation community) or sity evaluations vary considerably depending upon the sum of all such components within a given area their purpose, their scale and the biodiversity or site. Such evaluations may be carried out for a components in question. As stated previously, it is variety of reasons, e.g. for conservation priority vital that objectives be clearly defined and the setting, as part of Biodiversity Action Plan (BAP) work planned through to its conclusion. development, for the selection of Protected Areas, Spellerberg (1991) identifies the following six for the identification of a site’s features of conser- general best practices that should be included in vation interest, as part of conservation objective any evaluation framework. setting, management planning and monitoring processes, and as part of an EIA or other statement 1. Evaluation objectives should be defined. to comply with planning procedures for a proposed 2. Criteria should be quantifiable, rather than development. subjective. Evaluations may be carried out on various com- 3. Evaluations should be repeatable. ponents of biodiversity (i.e. from genetic variation 4. Evaluations should be based on biological within species, to individual species, species principles. assemblages, biotopes and biomes) and at a variety 5. The methods, results and analysis should be of scales, from specific sites, to counties, regions, explained so that they can be understood by every- countries, biogeographical areas (although these one who has an interest in the area being evaluated. may be smaller than countries) and global. A wide 6. Costs in time and money should take into account range of potential biodiversity values may be con- the depth and integrity of underlying surveys. sidered, including intrinsic and socio-cultural We have incorporated such concepts into a pro- values (Daily, 1997; Posey, 2000), and more direct posed generic framework for conducting site-based socio-economic benefits (Daily, 1997), such as food, biodiversity evaluations, as outlined in Figure 3.1. building resources, medicines and waste decomposition, etc. (Spellerberg & Hardes, 1992). 3.3 IDENTIFICATION OF VALUABLE As this Handbook concentrates on site surveys ECOSYSTEM COMPONENTS and monitoring, rather than on regional- or national-scale studies, this chapter focuses on site A key step in any evaluation is the identification of evaluations. We do not consider socio-economic biodiversity components or functions that are con- and socio-cultural values; the reader is referred to sidered to be important or valuable. These are

# RPS Group plc and Scottish Natural Heritage 2005. 66 3 BIODIVERSITY EVALUATION METHODS

Define scope and objectives

Consult with interested parties and local experts

Carry out preliminary survey Review existing biodiversity (scoping survey for EIAs) information

Identify habitats and main taxonomic groups present For EIAs etc, give special regard to legally protected species

Check existing Check lists of designation status species / habitats (e.g. SSSI, SPA, SAC, local Wildlife Site) of conservation concern

Identify Valuable Ecosystem Components (VECs) potentially present

Design survey

Survey and confirm presence of VECs and quantify if necessary and possible

Carry out evaluations against appropriate criteria with respect to objectives for:

Protected area selection Impact assessment in EIAs (against designation criteria)

Setting conservation objectives e.g. for features of interest

Figure 3.1. A generic framework for site biodiversity evaluation. called Valuable Ecosystem Components (VECs) by conservation agency terminology, VECs would at Treweek (1999) and are sometimes referred to else- least include notified features of interest. where as Valued Ecological Receptors or Valued The identification of VECs has a major and Ecological Resources. In SSSI and UK statutory obvious bearing on the outcome of any evaluation 3.3 Identification of Valuable Ecosystem Components 67

exercise, as an ecosystem, habitat or site will not be * species known to be sensitive to specific land use regarded as important if interest features are over- actions that may serve as ‘early warning’ or indi- looked. Indeed, one of the main underlying causes cator species for an affected wildlife community; of biodiversity loss is the lack of appreciation of the * species that perform a key role in a community value of its properties and functions. because, for example, of their role in nutrient It may not be practical to identify and use all VECs cycling or energy flows; and in an evaluation, even in the most simple habitats, * species that represent groups of species that uti- as too many species and other components and lise a common environmental resource (guilds). functions will have some value. It is thus normal to base evaluations on a sub-set of selected VECs of In the UK and elsewhere in Europe, the presence of particular value. For EIAs, however, it is necessary species or habitats of high conservation priority is to identify all VECs that are of more than negligible one of the most commonly used criteria for pro- value and which will receive impacts. The criteria tected area designation and consideration in EIAs. used to select or identify such VECs should be objec- The presence of particularly high numbers or high tive, consistent, transparent and defensible proportions of species (irrespective of their conser- (Treweek, 1999). Ecosystem attributes that may be vation status) is also a frequently used criterion for selected as VECs at a site may include distinct the selection of sites for protection for nature con- genetic populations of a species, species popula- servation purposes. For example, the internation- tions, species assemblages, vegetation communities, ally recognised criteria for the designation of habitats and ecosystem functions. Ramsar Sites (see Section 3.7.6) include thresholds In practice, species and habitats of particular for the proportion of biogeographic waterfowl conservation importance are the most commonly populations (e.g. more than 1% of the flyway popu- identified VECs as these are easiest to define objec- lation) and total waterfowl numbers (e.g. more tively and to measure quantitatively. In contrast, than 20 000 individuals). ecosystem functions, though perhaps of as great an The evaluation framework (See Figure 3.1) iden- importance as VECs, are difficult to define and tifies a number of activities that will assist in iden- describe in terms that allow objective evaluations tifying VECs. These include reviewing existing to be made of their importance. Nevertheless, this biodiversity information, consulting with local should be attempted as far as possible when it is experts (e.g. county recorders, biological records considered that a site is likely to provide an impor- centres, Wildlife Trusts) and conducting prelimin- tant ecological function. ary surveys. Even brief surveys are likely to be There are a variety of species attributes that valuable. They can establish the range of VECs may be used as criteria for their selection as VECs. that may be present, and this can help considerably These include commercial value, rarity, endanger- in the subsequent design of full surveys (or mon- ment, their role as flagship or umbrella species itoring). Although preliminary surveys will not be (i.e. ability to provide benefit to others through able to adequately establish the presence of all their conservation), their importance for ecosystem species VECs, they should identify habitats that function (i.e. keystone species) and their value as are present. This information may be used to iden- indicator species (See, for example, Eberhardt, tify potential species VECs, which may then be 1976; Treweek, 1999). verified by subsequent surveys. For example, a The US Fish and Wildlife Service Habitat brief site visit might establish that ponds are pre- Evaluation Procedure (HEP) (USFWS, 1980), sentfor that are suitable for, and within the vicinity example, identifies four categories of ‘evaluation of known populations of, Great Crested Newts species’: Triturus cristatus. A specific newt survey may then be planned and carried out at a suitable time. * species with public interest, economic value or Evaluation of sites on the basis of species- and both; habitat-based VECs requires some assessment to 68 3 BIODIVERSITY EVALUATION METHODS

have been made of the conservation status of the are not immediately threatened with extinction. As individual habitats and species in question. The a result, a suite of common but rapidly declining following sections therefore describe key princi- farmland birds, such as Turtle Dove Streptopelia ples underlying the assessment of species and habi- turtur, Skylark Alauda arvensis, Starling Sturnus vul- tat conservation priorities. Specific details and garis and Yellowhammer Emberiza citrinella, are guidance on assessments and legislation affecting now on the UK Red List (Gregory et al., 2002) and current species and habitat conservation priorities are a focus of considerable conservation action. within the UK are then provided in Section 3.5. Priority-setting under the UK Biodiversity Action Plan (BAP) process has also used broader criteria than just extinction risk in its selection of Priority 3.4 PRINCIPLES UNDERLYING THE Species. SETTING OF CONSERVATION PRIORITIES 3.4.2 The importance of rarity 3.4.1 Conservation objectives Rarity has often been considered to be one of the Conservation priorities depend in the first instance most important factors influencing the risk of on conservation objectives. In terms of global extinction of a species, and many Red Data lists objectives, there is reasonable agreement that the have focused on this. Rarity has also often been prevention of global extinction should be the focus used as a secondary criterion whereby, for example, of activity, in which case the degree of threat (i.e. a declining species is not considered to be threa- risk of extinction) is of primary concern in setting tened unless it is has also crossed a rarity threshold. priorities. This is reflected in the production of However, rarity is not a straightforward concept: IUCN Red Lists of species that are considered to be there may be a variety of circumstances under at risk of global extinction according to various which species may be rare (Rabinowitz, 1981). categories of threat. Beyond this, there are many Species may have small (or large) total ranges, different views on global biodiversity conservation occupy few (or many) habitat types, and be scarce priorities; such diversity of opinion is not surpris- or abundant where they do occur. As indicated in ing as there is no single feasible way of measuring the brief examples in Table 3.1, seven of the com- or valuing biodiversity overall (Purvis & Hector, binations of these factors (the shaded boxes) would 2000). qualify as rare within the possible range of mean- The risk of extinction at national level is also ings of the term. It is therefore evident that rarity probably the commonest basis for national species embraces both a spatial and a numerical dimen- conservation priority setting. However, at national sion. For any particular species some aspects of or sub-national levels biodiversity conservation is rarity may be an evolutionary property, such as increasingly incorporating broader multiple objec- habitat specificity, small natural range or low nat- tives. In the UK, for example, bird conservation ural densities. Such species may always be rare and objectives have traditionally focused on rare spe- therefore unlikely to respond to conservation mea- cies, but in recent years greater attention has been sures. On the other hand, small range or low den- given to species that occur in internationally sities may be the result of human impact, which important numbers, despite many of these being may be reversible. highly abundant (e.g. many species of wintering Inclusion of rarity factors in an evaluation waterbird). There is also increasing concern for requires data on the range or number of indivi- species that are common and widespread but duals of a species (or habitats, communities, or declining rapidly, as rapid declines of common abiotic features), not only at the site in question, species may involve the loss of many millions of but at wider scales. Important elements of rarity individuals from the environment. This is clearly a are also scale-dependent. A locally rare species may substantial biodiversity impact even if the species also be regionally or globally rare, or it may simply Tetrao Stercorarius Locally abundant over a small range in ahabitat specific Great Skua skua Constantly sparse over a small range in ahabitat specific Capercaillie urogallus Small Circus Anser (wintering) habitat use Narrow habitat use pygargus Locally abundant in several habitats over a small range Pink-footed Goose brachyrhynchus Constantly sparse over a small range in several habitats Montagu’s Harrier specificity and local population size Geographical range to range, population size and habitat use in the UK. Acrocephalus Anas querquedula Locally abundant over a large range in a specific habitat Reed Warbler scirpaceous Constantly sparse over a large range in a specific habitat Garganey Large Asio otus Turdus merula ). Constantly sparse over a large range in several habitats Long-eared Owl Common and locally abundant over a large range in several habitats Wide habitat use Narrow habitat use Wide 1981 The seven forms of rarity based on a species’ geographical range, habitat Rabinowitz ( Local population size Indicative bird species have been added for each category in relation Large, dominant somewhere Example birdsSmall non- dominant Blackbird Example birds Source: Table 3.1.

69 70 3 BIODIVERSITY EVALUATION METHODS

be rare because it is at the edge of its range (e.g. breeding Golden Orioles Oriolus oriolus or Redwings Turdus iliacus in the UK). Normally, increased impor- Stone-curlew White-tailed tance should be given to species that are rare on a Eagle global scale. Some locally abundant species may Scottish also be of high conservation importance if the spe- Crossbill Increasing cies in question is rare at a global or wide geogra- conservation priority phical scale (e.g. Great Skua Stercorarius skua and Risk of extinction Turtle Dove Great Crested Newt). Manx Shearwater Blackcap 3.4.3 Levels and scales of threat and population importance Global importance of the population / resource Whichever criteria are used for threat evaluations, a hierarchical level of importance should be estab- Figure 3.2. Key factors defining the conservation lished according to the scale of the assessment, so status of a species’ population or area of habitat. that the highest priority for conservation and/or (Scientific names of species: Stone-curlew Burhinus protection is given to species or habitats that are oedicnemus,White-tailed Eagle Haliaeetus albicilla, Turtle globally threatened. However, it is also necessary Dove Streptopelia turtur, Blackcap Sylvia atricapilla, to take into account their local status to assess the Manx Shearwater Puffinus puffinus, Scottish Crossbill necessity for taking action at a local scale. This Loxia scotica.) enables the principle of ‘thinking globally and acting locally’ to be put into practice. The highest the importance of the population or resource being priority should be given to species and habitats considered. Thus, the evaluation of a species’ popu- that are both globally and locally threatened. lation conservation status should consider two key Assessments below global scales should also independent factors: the risk of extinction of the refer to appropriate biogeographical populations. population in question (i.e. its threat status) and its In practice, however, assessments of populations biogeographical importance, i.e. the proportion it are more often based on national or regional (e.g. represents of the appropriate biogeographical (or European) populations for political and adminis- national or regional) population (Figure 3.2). The trative reasons. This is because some species could same conservation evaluation principles may be otherwise have more than one conservation status applied to an area of habitat. within a country, which would send confusing and Thus, for example, a very high priority should be mixed messages to policy makers and the general given to a species’ population that is endemic and public. Some steps towards defining conservation is at a high risk of extinction. However, it is import- status on the basis of biogeographic populations ant to note that a population may be a high priority have, however, been made for migratory water nationally because the species is highly threatened birds. Different waterfowl flyway populations nationally, irrespective of its numbers in relation have been defined (Rose & Scott, 1997) to enable to international or global populations (e.g. Stone- identification of important waterbird populations curlew in Figure 3.2). This is because the mainte- under the Ramsar Convention. These flyway popu- nance of a species’ range (and potential genetic lations have in turn been used to define threatened variation associated with this) can also be an impor- waterbird populations for the African–Eurasian tant conservation aim after prevention of complete Waterfowl Agreement, an agreement under the extinction. On the other hand, a population of a Convention on Migratory Species of Wild Animals. species may be very important because it is a large Any evaluation of conservation priorities for a proportion of the biogeographical population, irre- species (or habitat) should also take into account spective of its conservation status (e.g. Manx 3.4 Principles underlying the setting of conservation priorities 71

Shearwater in Figure 3.2). In these circumstances a National boundary: Regional boundary: country has a particular responsibility for the species and should at least take appropriate measures AAAAAAAAA to monitor the status of the species and guard AAAAAAAAA against potential events (e.g. an oil spill) that AAAAAAAAA could affect the population suddenly and catastro- AAAAAAAA phically, or gradually over a longer period of time. AAAAAAAA Such species are often the subject of national and DD AAAAAAAA local Biodiversity Action Plans (BAPs). DD AAAAAAA This concept of assessing both the risk of extinc- AAAAAA tion and the importance of the population can be CC E applied at a variety of scales. For example, for bird CCC E species, the status and importance of a population CCC BB EE on a site can be compared with that of the county, BBB country or biogeographic region (e.g. flyway). A BBB hypothetical example of national priority setting according to a species’ biogeographical range is Figure 3.3. National priority setting, based on a species’ depicted in Figure 3.3. regional(e.g.European)rangesizeandtheproportionof Although consideration of the biogeographical its range occurring within the country in question. Each importance of populations is not normally expli- species’ geographical range is represented by an array of citly carried out in the preparation of Red Data letters. Species A is widespread within the region, but Books (RDBs), this approach was developed by rare within the country. Species B and E are equally rare BirdLife International in its assessment of the con- within the country, but much less widespread within the servation status of European birds (Tucker & Heath, region as a whole. Species D has half of its range within 1994; BirdLife International, 2004). The highest of the country, whereas species C is endemic (and relatively four categories of Species of Conservation Concern widespread) within the country. If conservation status (SPECs) was given to species that were globally were to be assessed solely on the basis of national range threatened, irrespective of the proportion present size, species A, B and E would be of high priority for in Europe, because it was felt that these species conservation action or protection, and species D and C should be a high priority wherever they occur reg- less so. Alternatively, if regional range size is the sole ularly. However, the second highest priority (SPEC criterion used, species D and E would be accorded the 2) was given to those species that were considered highest priority, followed by B and C, then A. Finally, a to have an Unfavourable Conservation Status in national assessment based on the proportion of each Europe and populations that are concentrated (i.e. species’ range occurring within the country would select more than 50%) in Europe. Other species with an C, then D, followed by E, B and A. Ideally, national Unfavourable Conservation Status were placed in priority setting should attempt to balance all three the SPEC 3 category. measures: national conservation status, wider This approach has been taken further in the conservation status (regional or global) and degree of UK. The first RDB for birds in the UK (Batten et al., endemism. 1990) included the international importance of populations as one of its qualifying criteria. However, this concept was expanded with revised criteria in the subsequent reassessments and combined NGO and Agency Red and Amber-listed publication of Birds of Conservation Concern by UK birds (Gregory et al., 2002). These lists included non-governmental organisations (NGOs) (Gibbons the BirdLife International SPEC categories 1–3 as et al., 1996), Birds of Conservation Importance by the well as species with internationally important UK Statutory agencies (JNCC, 1996) and the populations. 72 3 BIODIVERSITY EVALUATION METHODS

Table 3.2. Species traits other than population status that have been used for ranking between-species conservation priorities

Trait Priority given to Example references

Evolutionary Species with most unique characters Vane-Wright et al. (1991) uniqueness Species with greatest genetic diversity Crozier (1992, Nee and May (1997) Species in cladesa undergoing evolutionary Erwin (1991) radiations Phenotypic traits Maximising diversity of phenotypic traits Owens & Bennett (2000) Protection status Species poorly represented in protected Scott et al. (1993), Cassidy et al. (2001) areas Land use change Species in areas susceptible to destruction Menon et al. (2001) Ecosystem role Species important in ecosystems (e.g. Allen-Wardell et al. (1998) pollinators) Multi-species Maximal phylogenetic diversity within a set Witting et al. (2000) interactions of interacting species a A group of species (in this instance) sharing a closer common ancestry with one another than with members of any other clade. Source: (Mace & Collar, 2002).

3.4.4 Other factors affecting species 3.5 SPECIES AND HABITAT conservation priorities CONSERVATION PRIORITY LISTS

Factors other than population status or range size There are a large number of conservation assess- may influence the overall conservation priority ments and legislative instruments that should ranking for a species or habitat, examples of which be taken into account in any evaluation of are listed in Table 3.2. Most of these have rarely been a species’ or habitat’s conservation priority. In applied. However, genetic diversity is increasingly the UK ecological evaluations should take special being incorporated into decision-making in relation note of: to rare and/or threatened species. A species distributed across a number of isolated sites, e.g. Pollan * IUCN global Red Lists Coregonus autumnalis pollan in lakes in Ireland, has * Convention on Migratory Species Appendices a potentially high genetic biodiversity; and each * Bern Convention Appendices 1, 2 and 3 isolated population contributes to the diversity * European Red Lists or lists of species of conserva- within the species and hence its overall ability to tion concern survive. In the case of Floating Water-plantain * Wild Birds Directive Annex I Luronium natans, much of the population in the UK * Habitats Directive Annex I and 2 is found in the canal network and is thought to * Wildlife & Countryside Act Schedules 1, 5 and 8 derive from vegetative reproduction from a single * CROW Act 2000 list of habitats and species under population in Wales. If this is the case, the canal Article 74 (for England and Wales only) plants have relatively low genetic diversity com- * Nature Conservation Act 2004 (Scotland) pared with that of isolated lake populations and * UK Red Lists and birds of conservation concern would rank low in an evaluation. * UK BAP listed species and habitats 3.5 Species and habitat conservation priority lists 73

Background information on the derivation of each assessment of extinction risk, which can also be of these lists is outlined below. Further informa- consistently applied by different people across the tion and accounts of other lists referring to specific full range of taxa. All new assessments and reas- species groups are provided in each species sessments of IUCN Red Lists use this system. Some chapter. assessments from 1996 to 2000 have also been converted to follow the revised categories and cri- 3.5.1 IUCN Red Lists teria. It is now intended that SSC will leave this system unchanged for a sufficient period to allow The IUCN Red Lists and Red Data Books (RDBs) were genuine changes in conservation status to be first conceived in 1963 to draw attention to the monitored. conservation needs of globally endangered species. The current categories of threat are listed below In particular, the identification of endangered spe- and a diagrammatic summary of the relationships cies was carried out to assist with defining conser- between these categories is shown in Figure 3.4. vation priorities and the drafting of species protection The assessments may be made either by relating legislation. The Red Lists were prepared under the simple population status attributes to numerical auspices of the Species Survival Commission (SSC), thresholds or by a more complex Population one of the commissions of IUCN (The International Viability Analysis (PVA). PVAs use demographic Union for the Conservation of Nature). The selection models to predict the probability that a given popu- of species for inclusion was carried out by using lation will become extinct (or decline to a specified standard data sheets and largely subjective assess- level) within a given time period (see Beissinger & ments. Species were categorized according to threat: Westphal (1998) for review). Endangered, Vulnerable, Rare, Out Of Danger or Indeterminate. * Extinct (EX): A taxon is Extinct when there is no This simple priority classification set a global reasonable doubt that the last individual has died. standard for conservation assessment for more A taxon is presumed Extinct when exhaustive than 30 years. By the late 1980s discussions were surveys in known and/or expected habitat, at taking place on how the criteria could be quanti- appropriate times (diurnal, seasonal, annual), fied to make the selection process more objective throughout its historic range have failed to record (Fitter & Fitter, 1987). After an extensive period of an individual. Surveys should be over a time frame preparation and consultation, IUCN adopted more appropriate to the taxon’s life cycle and life form. precise and quantitative Red List Categories in 1994 * Extinct in the wild (EW): A taxon is Extinct in the (IUCN, 1994). These criteria (referred to as Version Wild when it is known to survive only in cultiva- 2.3) were used for the 1996 IUCN Red List of Threatened tion, in captivity or as a naturalised population Animals (Baillie & Groombridge, 1996), The World List (or populations) well outside the past range. A of Threatened Trees (Oldfield et al., 1998) and the 2000 taxon is presumed Extinct in the Wild when IUCN Red List of Threatened Species (Hilton-Taylor, exhaustive surveys in known and/or expected 2000). habitat, at appropriate times (diurnal, seasonal, Then, in 1996, IUCN members called for a annual), throughout its historic range have failed further review to ensure that the criteria were to record an individual. Surveys should be over a applicable to a wide range of organisms, especially time frame appropriate to the taxon’s life cycle long-lived species and species under intensive and life form. management. As a result a further revised set of * Critically Endangered (CR): A taxon is Critically threat categories and criteria was adopted by IUCN Endangered when the best available evidence Council in 2000 and published in 2001 as Criteria indicates that it meets any of the criteria A to E Version 3.1 following further refinement (IUCN, for Critically Endangered, and it is therefore con- 2001). The aim has been to develop a method and sidered to be facing an extremely high risk of set of criteria that provide a more objective extinction in the wild. Criteria A to D relate to 74 3 BIODIVERSITY EVALUATION METHODS

Extinct (EX)

Extinct in the Wild (EW) Critically Endangered (CR) (Adequate data) (Threatened) Endangered (EN)

Vulnerable (VU)

(Evaluated) Near Threatened (NT)

Least Concern (LC)

Data Deficient (DD)

Not Evaluated (NE)

Figure 3.4. Current IUCN Red List threat categories (IUCN, 2001).

numerical thresholds for species in rapid decline, qualifying or likely to qualify for a threatened with small, fragmented, declining or fluctuating category in the near future. ranges, or with very small populations or ranges. * Least Concern (LC): A taxon is Least Concern Criterion E is an unfavourable PVA indicating a when it has been evaluated against the criteria probability of extinction of more than 50% and does not qualify for Critically Endangered, within ten years or three generations (whichever Endangered, Vulnerable or Near Threatened. is longer). Widespread and abundant taxa are included in * Endangered (EN): A taxon is Endangered when this category. the best available evidence indicates that it * Data Deficient (DD): A taxon is Data Deficient meets any of the criteria A to D for Endangered, when there is inadequate information to make a and it is therefore considered to be facing a very direct or indirect assessment of its risk of extinc- high risk of extinction in the wild, or if under tion based on its distribution and/or population Criterion E it has a PVA indicating a probability status. A taxon in this category may be well stu- of extinction of more than 20% within 20 years or died, and its biology well known, but appropriate five generations. data on abundance and/or distribution are lack- * Vulnerable (VU): A taxon is Vulnerable when the ing. Data Deficient is therefore not a category of best available evidence indicates that it meets any threat. Listing of taxa in this category indicates of the criteria A to D for Vulnerable, and it is that more information is required and acknowl- therefore considered to be facing a high risk of edges the possibility that future research will extinction in the wild, or if under Criterion E it show that threatened classification is appropriate. has a PVA indicating a probability of extinction of It is important to make positive use of what- more than 10% within 100 years. ever data are available. In many cases great care * Near Threatened (NT): A taxon is Near Threatened should be exercised in choosing between DD and a when it has been evaluated against the criteria but threatened status (CR, EN or VU). If the range of a does not qualify for Critically Endangered, taxon is suspected to be relatively circumscribed, Endangered or Vulnerable now, but is close to and a considerable period of time has elapsed 3.5 Species and habitat conservation priority lists 75

since the last record of the taxon, threatened sta- species listed in Appendix I of the Convention and tus may well be justified. by concluding multilateral Agreements for the con- * Not Evaluated (NE): A taxon is Not Evaluated servation and management of migratory species when it has not yet been evaluated against the listed in Appendix II. The Bonn Agreements of criteria. direct relevance to terrestrial and freshwater habitats and species in the UK at the moment are the Full details of the current IUCN Red List Categories African-Eurasian Migratory Waterbird Agreement and criteria are provided in IUCN (2001). They can also and the Agreement on the Conservation of be obtained together with guidelines on their use at Populations of European Bats (EUROBATS). http://www.redlist.org/info/categories_criteria.html. The CMS is typically implemented legally The most recent published list of globally threa- through the legislation of any given country and/ tened species is in 2004 IUCN Red List of Threatened or the European Union, for example in the UK, the Species (Baillie et al., 2004). An updated list of threa- Wildlife & Countryside Act, the EU Birds Directive tened taxa is maintained in a searchable database (79/409/EEC) and the EU Habitats Directive by the SSC Red List Programme accessible at (92/43/EEC). www.redlist.org/. However, the only taxonomic groups that have been comprehensively assessed are the birds and mammals. The vast majority of 3.5.3 Bern Convention plant taxa listed in the 1997 IUCN Red List of The Convention on the Conservation of European Threatened Plants (Walter & Gillett 1998) have not Wildlife and Natural Habitats, also known as the yet been evaluated against the revised Red List Bern Convention, was adopted on September 1979 Criteria and are therefore not included. Instead, in Bern (Switzerland) and came into force on 1 June the conservation status of plants may be ascer- 1982. It now has 45 Contracting Parties including tained by searching the SSC database and the 39 Member States of the Council of Europe as well UNEP-WCMC Threatened Plants database at http:// as the European Community, Monaco and four www.wcmc.org.uk/species/plants/red_list.htm. African states. Most Red List assessments are carried out by The aim of the Convention is to: the members of the IUCN Species Survival Commission. All the birds are assessed by BirdLife * conserve wild flora and fauna and their natural International and its partners. Other assessments habitats; and much taxonomic and distribution information * promote co-operation between states; and have been provided by various partner * give particular emphasis to endangered and organisations. vulnerable species, including endangered and vulnerable migratory species.

3.5.2 The Bonn Convention The contracting parties have undertaken, inter alia, to protect the habitats of wild flora and fauna spe- The Convention on the Conservation of Migratory cies, and to give special attention to the conserva- Species of Wild Animals, more often known as tion of the species listed in: the Bonn Convention (or CMS), aims to conserve * Appendix I: strictly protected flora species. terrestrial, marine and avian migratory species * Appendix II: strictly protected fauna species. throughout their range. It is one of a small number * Appendix III: protected fauna species. of intergovernmental treaties concerned with the conservation of wildlife and wildlife habitats on a This Convention has greatly influenced the devel- global scale. opment of EU nature conservation legislation, Parties to the CMS work together to conserve being the inspiration for the EU Birds and migratory species and their habitats by providing Habitats Directives. It has also had an important strict protection for the endangered migratory influence on the UK’s main conservation 76 3 BIODIVERSITY EVALUATION METHODS

legislation, the Wildlife & Countryside Act In 1992 the then European Community adopted 1981. See http://www.nature.coe.int/english/cadres Council Directive 92/43/EEC on the Conservation /bern.htm for more information on the Bern of Natural Habitats and of Wild Fauna and Flora, Convention and lists of species on the various known as the Habitats Directive. This international Appendices. wildlife legislation is intended to provide EU Member States with a mechanism to meet their 3.5.4 European Red Lists and lists of obligations under the 1979 Bern Convention (see Species of Conservation Concern above) and to complement the provisions of the 1979 Birds Directive. The main aim of the European Red Lists or their equivalent have been Habitats Directive is: produced for some taxa. For example, BirdLife ...to contribute towards ensuring biodiversity through the International has produced lists of Species of conservation of natural habitats and of wild fauna and flora Conservation Concern (SPECs) in Europe (Tucker & in the European territory of the Member States to which the Heath, 1994; BirdLife International, 2004). As Treaty applies (Article 2). described above, this does not use IUCN criteria but develops these and includes assessments of the The 24 articles of the Directive specify a range of importance of European populations as well as measures, including conservation of features in the their threat status. Further information on the cate- landscape that are important for wildlife, the pro- gories and criteria used for SPECs is given in Part III, tection of species listed in the annexes from Chapter 24 on birds. damage, destruction or over-exploitation, the sur- A European Red List has also been produced by veillance of natural habitats and species, and the Council of Europe for butterflies (http:// ensuring that introductions of non-native species www.vlinderstichting.nl/en/randc/rdb.htm). are not detrimental to naturally occurring habitats and species. One of the most stringent obligations (under Article 3) is to select, designate and protect a 3.5.5 European Union Birds and Habitats series of sites, to be called Special Areas of Directives Conservation (SACs), for 169 natural Habitats of In 1979, the European Community adopted Council Community Interest listed in Annex I of the Directive 79/409/EEC on the conservation of wild Directive and 623 Species of Community Interest 1 birds in response to the 1979 Bern Convention. listed in Annex II . This Directive, usually referred to as the Birds Habitat types of Community Interest are, within 2 Directive, provides for the protection, management the EU territory : and control of naturally occurring wild birds within 1. in danger of disappearance in their natural range; the European Union through a range of mechan- or isms. One of the key provisions (under Article 4) is 2. have a small natural range following their regres- the establishment of an internationally co-ordi- sion or by reason of their intrinsically restricted nated network of protected areas, known as area; or Special Protection Areas (SPAs) for 182 species listed 3. present outstanding examples of typical charac- in Annex I of the Directive. These are species that are teristics of one or more of the five following considered to be in danger of extinction, vulnerable biogeographical regions: Alpine, Atlantic, to specific changes in their habitat, rare, or requir- Continental, Macronesian and Mediterranean. ing particular attention by reason of the specific nature of their habitat. Within SPAs, Member 1 States are obliged to take necessary steps to avoid Birds are not included because they are listed in Annex I of the Birds Directive. deterioration of natural habitats and disturbance of 2 Within EU territory: i.e. within the European territory of the the species, where this disturbance would be signif- Member States to which the Treaty establishing the European icant in terms of the objectives of the Directive. Economic Community applies. 3.5 Species and habitat conservation priority lists 77

Some of these Habitats of Community Interest are species, the liverwort Western Rustwort given priority status because the Community has a Marsupella profunda. Further information on their particular responsibility for their conservation in occurrence is given in McLeod et al.(2002). view of the proportion of their natural range which Together the SACs and SPAs are known as the falls within the EU territory. The importance of Natura 2000 network. This network will provide these Priority Habitat types is emphasised at sev- the most stringent protection mechanism for eral places in the Directive (Articles 4 and 5 and many habitats and species with restricted ranges Annex III), not only in terms of the selection of or small populations. However, for other more dis- sites, but also in the measures required for site persed species (e.g. those associated with many protection (Article 6) and surveillance (Article 11). farmland habitats), site designation is unlikely to Definitions and interpretations of the Habitats of protect more than a small portion of the total Community Interest have been provided by the resource. The Habitats Directive therefore also spe- European Commission Environment Directorate cifies that the conservation status of flora and (European Commission, 1999) and further informa- fauna should be maintained throughout their tion on their occurrence in the UK is given by range. McLeod et al.(2002). Of these Habitats of IntheUK,theDirectiveshavebeentransposedinto Community Interest, 76 are believed to occur in legislation by The Conservation (Natural Habitats, & the UK, of which 22 are Priority Habitat types. c.) Regulations 1994 and The Conservation (Natural Species of Community Interest (listed in Annex II Habitats, &c.) (Northern Ireland) Regulations 1995, of the Directive) are those that, within the EU ter- as amended (informally known as ‘The Habitats ritory are: Regulations’). Under British law all SACs and SPAs will be underpinned by SSSI designations. 1. endangered, except those species whose natural The UK submitted its first report to the European range is marginal in that territory and which are Commission summarising the implementation of not endangered or vulnerable in the Western the Habitats Directive in the UK from 1994 to Palaearctic region; December 2000 (Salmon, 2001). As of June 2003 2. vulnerable, i.e. believed likely to move into the there were 242 SPAs in the UK, covering some endangered category in the near future if the 1 470 000 ha. As of January 2004, 605 sites covering causal factors continue operating; or some 2 500 000 ha had been proposed as candidate 3. rare, i.e. with small populations that are not at SACs, and a further ten as proposed SACs covering present endangered or vulnerable, but are at risk. some 290 000 ha. As a matter of policy for planning The species are located within restricted geogra- and all other consent regimes, the UK phical areas or are thinly scattered over a more Government and the devolved administrations extensive range; or already treat candidate SACs as though they were 4. endemic and requiring particular attention by fully designated. reason of the specific nature of their habitat and/ or the potential impact of their exploitation on their habitat and/or the potential impact of their 3.5.6 Wildlife & Countryside Act exploitation on their conservation status. The Wildlife & Countryside Act 1981 was intro- A number of Species of Community Interest are duced as the principal mechanism for the legisla- also given priority status because the Community tive protection of wildlife in Great Britain. It does has particular responsibility in view of the propor- not extend to Northern Ireland, the Channel tion of their natural range which falls within the Islands or the Isle of Man. It has been subsequently EU territory. amended with significant changes relating specifi- In recent times 51 Species of Community cally to Scotland and England and Wales. This leg- Interest have been recorded in the UK, but only islation is the chief means by which the one Priority Species currently occurs as a native Convention on the Conservation of European 78 3 BIODIVERSITY EVALUATION METHODS

Wildlife and Natural Habitats (the ‘Bern Countryside Act 1981 in England and Wales up to Convention’) and the European Union Directives date. The importance of biodiversity conservation on the Conservation of Wild Birds and Natural is also given a statutory basis, requiring govern- Habitats and Wild Fauna and Flora are implemen- ment departments to have regard for biodiversity ted in Great Britain. The Act is divided into four in carrying out their functions, and to take positive parts. steps to further the conservation of listed species and habitats. * Part I is concerned with the protection of wildlife. Section 74 of the CROW Act requires the * Part II relates to the countryside and national Secretary of State for England and the National parks (and the designation of protected areas). Assembly for Wales each to publish a list of species * Part III covers public rights of way. and habitat types that are of principal importance * Part IV deals with miscellaneous provisions of for the conservation of biological diversity in the Act. England and Wales, respectively. The Section 74 Sections 1–8 of Part 1 relate to the protection of list for England can be viewed on the DEFRA web birds. Section 1 prohibits the intentional killing, page http://www.defra.gov.uk/wildlife-countryside/ injuring or taking of any wild bird and the taking, cl/habitats/habitats-list.pdf. The equivalent list for damaging or destroying of the nest (while being Wales can be viewed on the National Assembly for built or in use) or eggs. It prohibits possession of Wales website: http://www.wales.gov.uk/subienvir- wild birds (dead or alive) or their eggs. There are onment/content/guidance/species-statement-e.htm. additional penalties for offences relating to birds These two lists are based on UK Biodiversity Action on Schedule 1, and it is also an offence to disturb Plan (UK BAP) Priority Habitats and Species lists. Schedule 1 birds at the nest or the dependent In England, The England Biodiversity Strategy young of Schedule 1 birds. Section 2 outlines excep- (DEFRA, 2002), developed under the UK BAP tions to Section 1: notably, it identifies quarry and process, is the principal means by which the pest species. Government complies with its duties to conserve, Section 9 prohibits the intentional killing, injur- and promote the conservation of, habitats and ing or taking of, the possession of and the trade in species listed under Section 74 of the Act. The list wild animals listed on Schedule 5. In addition, will be kept under review and a report on any places used for shelter and protection are safe- necessary revisions will be made as part of the guarded against intentional damage, destruction first report on progress on the Biodiversity and obstruction; animals protected under the rele- Strategy for England. vant part of Section 9 must not intentionally be disturbed whilst occupying those places. Section 13 identifies measures for the protection 3.5.8 Nature Conservation (Scotland) of wild plants. It prohibits the unauthorised inten- Act 2004 tional uprooting of any wild plant species and for- bids any picking, uprooting or destruction of plants In a similar way the Nature Conservation (Scotland) listed on Schedule 8. It also prohibits the sale, or Act 2004 overhauls the current legislation concern- possession for the purpose of sale, of any plants on ing SSSIs and the protection of wildlife in Scotland Schedule 8 or parts or derivatives of Schedule 8 and gives a statutory basis for the Scottish plants. Biodiversity Strategy (SBS). It aims to make the SSSI system more adaptable and efficient and 3.5.7 The CROW Act 2000 strengthens the legal protection of specified species of plant and animal. The Act imposes a The Countryside and Rights of Way Act 2000 new duty on public bodies ‘in exercising any (CROW Act) strengthens the legal protection for functions, to further the conservation of biodiver- threatened species and brings the Wildlife & sity so far as is consistent with the proper 3.5 Species and habitat conservation priority lists 79

exercise of those functions’. The Act refers them to extinction risks within the region. Less often, the SBS, which elaborates on what this duty may upgrading may occur where the population within involve. the region is a demographic sink, such that it is The SBS is underpinned by a series of five imple- unable to sustain itself, and where the extra-regio- mentation plans, a research strategy and a set of nal source is expected to decrease. To date these biodiversity indicators. Details can be found at guidelines and the IUCN (2001) criteria have not www.scotland.gov.uk/biodiversity. The Scottish been applied in any UK Red Lists, but have been Executive is also publishing lists of those habitats used elsewhere, e.g. for birds in Sweden, Finland and species considered to be of principal impor- and Switzerland. tance in respect of the new responsibilities placed However, the IUCN criteria still only focus on on public bodies. establishing extinction probabilities and do not prioritise species according to the importance of 3.5.9 National Red Lists and lists of the biogeographical populations in question. This species of conservation concern lack of a ‘big-picture’ view can result in some important priorities being missed (Mace & Collar, A wealth of Red Lists have been produced in the UK, 2002). In the UK, and other developed countries and elsewhere, on species that are considered to be with relatively low levels of biodiversity, there is at risk of national extinction (as described in Part III also justification for giving attention to species that of this Handbook). These have typically adapted the remain relatively common (and thus are currently early IUCN criteria and used the same largely sub- at a very low risk of extinction) but are nevertheless jective categories of threat (see Section 3.5.1). This declining. Consequently, some recent assessments has tended to produce lists that are dominated by of the conservation status of species in the UK have rare species, many of which are likely to be at the moved away from the narrower Red Listing of edge of their range, and hence these lists under- threatened species to more inclusive lists of species value global priorities. Application of the new of conservation concern, which, for example, quantitative IUCN (2001) criteria is also problema- include species with internationally important tical at regional or national levels, as conspecific populations and common but declining species. populations (i.e. populations of the same species) Such an approach has been taken for birds in the may support the population of interest. IUCN UK (Gregory et al., 2002) and all species under the (2003) have therefore produced guidelines for the UK BAP. regional and national application of the IUCN Red Lists and other lists of species of conserva- (2001) Red List criteria that go some way to over- tion concern should therefore be taken into coming the problems described above. It should account in evaluations as appropriate to their also lead to greater standardisation of criteria, underlying objectives and particular assessment which will aid comparisons between countries. criteria. Detailed descriptions of such UK lists for According to the IUCN guidelines, regional and each species group are given later in the appropri- national assessments should be carried out in a ate chapters of this Handbook. two-step process, which differs slightly for breeding and non-breeding populations. In Step 1, the 3.5.10 UK Biodiversity Action Plan listed IUCN 2001 Red List criteria are applied to the popu- habitats and species lation in question, resulting in a preliminary categorisation. In Step 2, the existence and status of any The Biodiversity Convention was ratified by the UK conspecific populations outside the region that Government in June 1994. However, even before may affect extinction risks is taken into account. this, the Government had committed itself to For example, preliminary categories should be produce a consultative national action plan, downgraded (i.e. to a lower threat status) if immi- Biodiversity: the UK Action Plan (Anon., 1994) gration from outside the region is likely to reduce based on the principles of the Biodiversity 80 3 BIODIVERSITY EVALUATION METHODS

Convention. This plan was launched with the over- habitats of community importance, is provided in all goal: ‘to conserve and enhance biodiversity Appendix 2. within the UK and to contribute to the conserva- Species that qualify under one or more of the tion of global biodiversity through all appropriate following criteria should be considered as Species mechanisms’. of Conservation Concern (SoCC) : The plan stated that this is to be achieved * Threatened endemic and other globally threa- through the conservation and, where practicable, tened species; enhancement of: * Species where the UK has more than 25% of the * the overall populations and natural ranges of world or appropriate biogeographical population; native species and the quality and range of wild- * Species where numbers or ranges have declined by life habitats and ecosystems; more than 25% in the last 25 years; * internationally important and threatened species, * In some instances, where a species is found in habitats and ecosystems; fewer than fifteen 10 km squares in the UK; and * species, habitats and natural and managed ecosys- * Species listed in the EU Birds or Habitats tems that are characteristic of local areas; Directives, the Bern, Bonn or CITES Conventions, * the biodiversity of natural and semi-natural habi- or under the Wildlife & Countryside Act 1981 and tats where this has been diminished over recent the Wildlife Order (Northern Ireland) 1985. decades. Species that qualify for one or both of the follow- By October 1999, three hundred and ninety-one ing categories should be considered as Priority Species Action Plans (SAPs) and 45 Habitat Action Species: Plans (HAPs) had been published in reports pro- * Species that are globally threatened; duced by the UK Steering Group (UKSG, 1995a,b; * Species that are rapidly declining in the UK, i.e. by UKBG, 1998a,b,c, 1999a,b,c). more than 50% in the past 25 years. As part of the development of the UK BAP, lists were produced of Priority Habitats and Species The intention is that all Priority Species should be requiring conservation actions. Priority Habitats the subject of conservation action through the were defined3 as: development of SAPs. A full list of UK BAP Priority Habitats, SoCCs, further notes on their selection * Habitats for which the UK has international criteria and current versions of HAPs and SAPs are obligations; available from the UK BAP website library at * Habitats at risk, such as those with a high rate of www.ukbap.org.uk/Library. decline, especially over the past 20 years, or which The UK BAP listing of species is primarily are rare; for guiding strategic conservation priorities * Habitats that may be functionally critical (i.e. and therefore reference to SoCC lists with respect areas that are part of a wider ecosystem but pro- to site evaluations is not always appropriate. vide reproductive or feeding areas for particular Implementation of necessary actions for SoCC species); and species will be largely through the SAPs and coun- * Habitats that are important for UK BAP Priority try strategies such as the England and Scottish Species (see below). Biodiversity Strategies. Many SoCC species are All EU Habitats of Community Interest (Annex I) also common and widespread, such as the Song occurring within the UK are included as UK BAP Thrush Turdus philomelos (a Priority Species), Priority Habitats. A full list of UK BAP Priority and site-based actions may not be of significant Habitats, indicating their relationship to EU benefit for such species. Reference should therefore be made to individual SAPs to assess the 3 Two additional categories were identified and adopted for importance of site-based measures for SoCC marine habitats. species. 3.6 Site evaluations and selection of protected areas 81

incorporating complementarity considerations. 3.6 SITE EVALUATIONS AND SELECTION Simple criterion-led approaches typically define a OF PROTECTED AREAS standard (e.g. area of a particular habitat of conser- 3.6.1 General principles and criteria vation importance, or threshold number of individuals of a species of conservation importance) such One of the commonest reasons for undertaking that all sites exceeding this standard are included ecological evaluations is to assess the importance in the protected area series. of a site in relation to potential designation as some An important advantage of this approach is that it form of protected area. Evaluations may also be is simple and can be applied gradually, with sites carried out at a later stage for management plan- added sequentially to the series as data become avail- ning or related purposes to identify, or confirm, the able. The conservation importance of features, habi- important features (such as species or habitats) that tats and species needs to be reasonably well known, are present and that qualify the site for a particular but the location of all habitats and species of con- designation status. servation importance within the territory being con- The approaches and methods used for identify- sidered does not need to be known in advance. ing areas that should receive some form of protec- One of the problems with a criterion-led tion vary widely and depend on the overall approach is that it is open-ended, such that sites objectives for individual sites and the series of pro- are added no matter how much of a resource has tected areas within a given territory (Williams, been given protection. Thus, overall representation 1998; Margules & Pressey, 2000). However, an over- targets for species or habitats in a protected area all set of principles for protected area selection is series are not explicitly stated beforehand. This given by Ratcliffe (1977), who suggests that priority may be acceptable if the aim is to protect all sites should be given to sites and features that: above a defined value, but may result in problems if * are intrinsically most fragile and sensitive to criteria turn out to be too inclusive or too restrictive. human impact; To overcome such problems, the idea of setting * have already been reduced in area or quality objectives for a protected area network as a whole through human impact; has emerged and is receiving increasing support. * are predictably most vulnerable to further Target-setting can also explicitly ensure that the damage and loss through a combination of fragi- series of sites contains adequate representation of lity, sensitivity and probable expansion of impact; the total territory range of habitats, vegetation * would represent the greatest loss to nature con- communities, species assemblages and individual servation if they were damaged or destroyed; and species that are considered to require protection. * would be the most difficult to restore or re-create However, this needs to be carried out against a if they were damaged or destroyed. classification of the range of variation in habitats, communities and species, which the series of sites A variety of approaches have been developed for is intended to represent. The minimum aim of the identifying sites that should be included in a pro- representative principle would therefore be to tected area series, most of which focus on the select a series of sites that complement one fourth point above, i.e. evaluations of a site’s eco- another in terms of the habitats or species present. logical importance. Ideally, each habitat or species should be represented by at least one, and preferably the best, Threshold criteria versus target-led approaches example. However, in the face of existing threats The selection of protected areas is essentially based to sites this approach is unlikely to be sufficient to on a process of comparison, usually with certain maintain the representative set of habitats and selection criteria. These can be broadly categorised their characteristic features. An important princi- as simple criterion-led approaches, selection meth- ple of site selection should therefore be that as ods based on targets, and selection strategies rarity, threat or other ecological values increase, 82 3 BIODIVERSITY EVALUATION METHODS

then so does the need to ensure that a larger pro- the degree of flexibility in the series and irreplace- portion of the habitat or species’ population is ability of individual sites to be evaluated. under protection. Irreplaceability is particularly important because In practice, most protected area series have been the loss of the more irreplaceable sites in a series selected by using simple criterion-based systems closes options of ever achieving a representative within an overall representation target framework. protected area system. Irreplaceability provides a This is probably because it is easier to make relative single measure of conservation value of a site that judgements about the conservation value of habi- is defensible (Bibby, 1998). Thus, some algorithms tats and species than it is to make difficult a priori give a high priority to sites that contain species or decisions on how much should be protected. habitats that are not found elsewhere. Some algo- Protection targets also often tend to be arbitrary rithms also check back to ensure that early choices and unless widespread consultation is undertaken remain appropriate after the inclusion of others. they will have little ownership or acceptance out- Using such an approach, Williams et al. (1996) side the conservation community. identified a set of twenty-seven 10 km 10 km grid squares in which all British breeding birds were Complementarity considerations represented at least once. Similarly, Hacker et al. Criterion-led approaches (which, as described (1998) showed that all African primate species below, often focus on species rarity and diversity) occur within a set of grid squares that cover just tend to result in selection of sites that are similar in 3.8% of the area sampled. terms of their range of habitats and species. Such However, despite a great deal of research being approaches are therefore inefficient in the selec- carried out into protected area selection techni- tion of sites where objectives focus on representa- ques, selection algorithms and other computerized tion across a network of sites. Instead, an approaches have been used only infrequently by evaluation of the degree to which species commu- those involved in making decisions on the estab- nities complement each other may help identify a lishment of protected area networks (Prendergast minimum set of sites or area of land required to et al., 1999). This appears to be mainly because safeguard all species within a particular group decision-makers are unaware of the sophisticated (Vane-Wright et al., 1991; Howard et al., 1997; computer tools for reserve selection. Where this is Balmford & Gaston, 1999). This involves identifying not the case, there have been problems with fund- a series of sites whose habitats or species lists lar- ing and with understanding of the tools, and a gely complement each other. general antipathy towards what is seen as a pre- The majority of protected area selection techni- scriptive approach to conservation. There are also ques incorporating complementarity do so by common methodological limitations to its applica- using iterative steps; at each step all sites are com- tion, including the following: pared to test how well they complement areas that have already been chosen. The most straightfor- * Inadequate data on species and habitat distributions. ward approach, which uses a so-called ‘greedy’ Selection algorithms can only be fully applied algorithm (i.e. rule-based calculation), first selects when species distributions are well known and the area that is richest in the selected feature of the contents of potential nature reserves deduced. interest (e.g. threatened species), then selects the Consequently, as noted by Sutherland (2000), area that adds the highest number of features that where there are sufficient data for carrying out are not in the first. It then selects the area that adds such analyses, protected area networks are usually the highest number of features that are not present already well established. in either of the first two, and so on. * Differences in scale. There is often a substantial mis- Alternatives include various weighted algo- match between the resolution at which distribu- rithms, including ones that consider a site’s level tion data are available and the scale at which of irreplaceability (Pressey et al., 1994). This allows protected areas are designated. Indeed, data 3.6 Site evaluations and selection of protected areas 83

resolution is often close to one order of magnitude in their ecological characteristics. Thresholds of greater than the average size of protected areas significance, for instance size or species diversity, (Hopkins et al., 2000). might differ significantly between habitat types or * Dependence on presence–absence data. A species’ pre- biogeographical regions. It is therefore advisable to sence at a site does not necessarily mean that it group sites for evaluation into similar types before has a viable population there. Areas selected by comparisons are carried out. using complementarity may miss the best examples More detailed consideration is given below to of certain species’ populations, particularly of five of the most widely used criteria. those associated with species-poor areas. Some selection algorithms have therefore been refined Rare or abundant species to take account of species abundance rather than Many protected areas have been selected and desig- mere presence–absence (Turpie, 1995). nated purely on the basis of the occurrence of spe- * Political and economic considerations. Sites selected cies. This is largely because species provide the through complementarity analysis may not neces- simplest quantifiable and most objective currency sarily offer the best opportunities for successful of conservation value. Most species-based selection long-term conservation. In practice, the selection criteria assess a site’s importance for particular of protected areas is usually strongly influenced rare species or other species of conservation impor- by political considerations, opportunities, land tance and/or the abundance of species. prices (Ando et al., 1998), the threat of local devel- Such approaches have been frequently used for opment (Margules & Usher, 1981), or proximity to the selection of protected areas for birds. For example, existing reserves. Accordingly, reserve selection the Ramsar Convention includes a criterion for algorithms have recently been developed that designating Ramsar sites on the basis of the pre- incorporate rules for including mandatory areas, sence of 20 000 waterfowl or more than 1% of a forcing adjacency and excluding undesirable flyway population (see Section 3.7.6 below). areas (Lombard et al., 1997). BirdLife International has taken this type of approach and developed it to create a standard set 3.6.2 Evaluation and selection criteria of global criteria and regionally specific criteria for identifying Important Bird Areas (IBAs), which Although no standard set of criteria has emerged BirdLife recommend should receive appropriate for the purpose of site evaluations, assessment cri- statutory protection (Heath & Evans, 2000). teria have commonly focused on the presence of The species occurrence approach is also increas- certain rare (or otherwise threatened) species or ingly being applied to other taxa. For example, habitats, diversity, size and naturalness. Other cri- PlantLife International has developed criteria for teria have included fragility, degree of threat, edu- Important Plant Areas for Europe (Anderson, cational, scientific, recreational and cultural value, 2002), which include thresholds for the presence ecological or geographical location, the presence of of rare species (as well as rare habitats). potential buffer areas, shape, accessibility and potential conservation effectiveness (see Smith & Diversity Theberge (1986) for review). Species and habitat diversity has been one of the Whichever criteria are used, to be defensible they most frequently used evaluation measures for bio- need to be objective, explicit, based on widely tic communities. Selection of diverse sites tends to accepted ecological scientific principles and the be favoured because they are believed to contain best available data, and (ideally) quantifiable. more of the variety of natural resources within a However, criteria have varied widely in this respect. given area; however, problems may arise if comple- It is also important to remember that criteria mentarity is not taken into account. There are also will not be meaningful if applied across a wide less tangible aesthetic values in diversity and it has range of sites and habitats that differ considerably often been suggested that diversity is a factor 84 3 BIODIVERSITY EVALUATION METHODS

promoting ecosystem stability, but this idea is not Consequently, habitat richness indicators need to well founded in observation or theory (Bibby, be related to expected levels of species richness for 1998). habitats and, ideally, ecological regions. Species or habitat richness (measured in num- Degradation of natural habitats can also actually bers of species occurring) are the most intuitively result in an increase in overall biodiversity even simple measures of diversity. However, if popula- though species of conservation importance may tion sizes or areas are measured, they can be decline. Thus, species richness and diversity mea- combined into more sophisticated diversity surements should also focus on those species that indices (Magurran, 1983). TwoP commonly used are characteristic of the habitat, and not on the indices are Shannon’sP Index, (pi ln pi), and overall richness of the habitat. 2 Simpson’s index, 1 pi . Here, pi is the propor- In practice, diversity scores have been little used tion of individuals in the population belonging to for protected-area selection. However, some eva- species i. In each case, a high value indicates a luation scoring systems have been developed that large number of species with similar abundances, combine abundance, species conservation value whereas a low number indicates domination by a and species richness data. For example, in the UK few species. The requirement for abundance this approach has been used for selecting SSSIs information makes the measurement of diversity (NCC, 1989) for birds and amphibians (see Part III). more time-consuming, however, and indices are The Environment Agency (EA) have also devel- more difficult to interpret than species or habitat oped a Community Conservation Index (CCI) for numbers. evaluating the conservation importance of riverine Species richness measurements also depend on macro-invertebrate communities. Although this the scale at which they are measured; richness has not been introduced into full use yet by EA, it invariably increases with the increasing size of has been used in a number of Environmental the area surveyed (MacArthur & Wilson, 1967; Impact Assessments. A CCI score is calculated by Rosenzweig, 1995). Such species–area relations first assigning tabulated Conservation Scores to are likely to occur as a result of environmental each species in the sample based on their national heterogeneity. Increasing the area will include conservation status. An overall CCI score is then additional habitat types, or variations within derived by calculating the mean Conservation these, depending on how habitats are defined. Score and multiplying this by a tabulated However, at large scales biogeographic and historic Community Score, which reflects either species factors may be important contributors. Species–area richness or the rarest taxon present (depending effects can be examined and corrected by regres- on whichever gives the highest score). A high CCI sion analysis. Richness estimates may also vary score indicates a site with high conservation value according to sampling effort (for instance the num- for its rare taxa or species richness. CCI scores can ber of quadrats measured). This can also be cor- vary from 1.0 (no conservation interest) to 30.0 þ rected for (although it is more complex) by (high conservation interest). rarefaction, which resamples the data to estimate the number of species for a fixed (smaller) sam- Size (extent) pling effort (Simberloff, 1972). The size of a site, typically its area but sometimes Particular care must be taken in interpreting the its length (linear habitats), depth or volume (e.g. results of richness and diversity assessments. For lakes), is important in modified environments example, some semi-natural habitats of high ecolo- where natural communities are fragmented and gical value are characteristically species poor. isolated. In more extensive habitats, it is less Indeed, Bibby (1998) suggests that the appeal of obvious because the boundaries may be difficult diversity as an indicator has almost certainly led to define. to under-representation of inherently less diverse Of foremost importance is the attainment of a habitats in many protected area systems. minimum size, which will vary according to the 3.6 Site evaluations and selection of protected areas 85 protection objectives. In a fragmented landscape Naturalness large blocks may be necessary to contain viable Naturalness is a criterion that is difficult to define populations of particular species (especially wide- objectively, yet it is highly valued in conservation ranging predators, such as large raptors or, outside assessment. The principal reason for valuing natur- the UK, Wolves Canis lupus, Lynx Lynx lynx, etc.). alness as a criterion for identifying sites for protec- Large sites may also be more likely to support inter- tion is that there is often a close relationship ior species, which are intolerant of habitat edges. between the naturalness of a habitat and its biodi- Larger sites may also be valued beyond the mini- versity value. For example, research on river inver- mum viable size, because large areas of habitat tebrate communities in England has starkly shown typically contain a greater diversity of habitats that diverse physical river reaches, as found in and species. Size may also influence the manage- more natural rivers, support invertebrate commu- ment options available, such as the ability to nities of much greater diversity than highly mod- resolve usage conflicts or to enable natural vegeta- ified or uniform ones (Smith et al., 1991). Perhaps tion succession and landscape-scale dynamics. most importantly, a high proportion of rare species Related to the issue of size is that of shape, and a are often associated with natural or near-natural site’s proximity and linkage to other similar habi- habitats, primarily because such habitats now tat blocks, as these factors may influence species tend to be rare in developed countries. occurrences through emigration and immigration. The application of the naturalness criterion is Based on biogeographical studies, some basic rules particularly relevant to habitats such as rivers of thumb have been proposed, and widely referred (Boon et al., 1996a) and other wetlands. It is also to, for the selection of nature reserves (Diamond, consistent with developments under the Water 1975). These are simply that: Framework Directive where the condition of riverine habitats will be related to definitions of pristine * larger areas are better than smaller areas; habitat. Application of the naturalness criterion to * one large area is better than separated areas of the other habitats needs some care and qualification as same total area; many that are of conservation value (such as moor- * adjacent areas are better than isolated areas; lands, heathlands, and flower-rich grasslands) are * linkages (‘corridors’) between areas are better plagioclimax habitats that have been maintained than completely isolated areas; by centuries of human intervention. Determining * clusters of areas are better than areas in a line; and naturalness therefore requires considerable knowl- * compact areas are better than linear areas. edge of individual habitats, the effects of long-term natural process on them, and their response to However, there have been many erroneous and human intervention. inappropriate applications of these island-biogeo- Other reasons for favouring natural habitats and graphy-based theories to site evaluation and the ecosystems have included the scientific need for sites selection of protected areas. Other factors need to at which to study natural ecological processes. There be taken into account in considering the optimal are also emotional and aesthetic factors at play in the size, distribution and shape of nature reserves. greater perceived value of wilderness and ecosystems Indeed, in many cases these other factors will be less tainted by humans (McCloskey & Spalding, 1989). more important. For example, in some circumstances, very small reserves might be appropriate, Representativeness for instance in safeguarding plants with minute This criterion (also occasionally referred to as typical- ranges. In linear habitats, such as rivers, other ness) aims to select sites that best represent a parti- properties such as length and continuity become cular habitat of interest and which possess as many important. These typically relate to their corridor desirable habitat characteristics and special features function, their value rising with the number or as possible. On closer analysis, however, it is clear areas of sites they are able to connect. that this selection criterion involves a mixture of 86 3 BIODIVERSITY EVALUATION METHODS

desirable attributes that are best separated. In other indices of habitat or species assemblage value, in words, the concept of representativeness is made up an attempt to provide more quantifiable and objec- of other separate commonly used ecological evalua- tive assessments. tion criteria of diversity in particular, but also to Several authors have proposed the use of multi- some extent of size and rarity. It may therefore be ple evaluation criteria, which are then given more appropriate to regard representativeness as an weights or priorities by using scoring systems. underlying principle, which site selection processes Scoring enables abstract evaluation criteria to be aim to satisfy, both within a single site and through expressed numerically and hence they can be used the totality of all sites, and then to satisfy this prin- more readily in decision-making. Various scoring ciple by the application of criteria relating to it. procedures have been developed and have been reviewed by Margules & Usher (1981), Smith & 3.6.3 Nature Conservation Review criteria Theberge (1986) and Usher (1986). Westman (1985) summarises the four main types of scale The use of multiple criteria that take into account and associated permissible mathematical and sta- the presence of species, habitat quality and other tistical operations associated with scoring ecological factors gives a better integrated assess- procedures. ment of the overall value of a site than does concen- Although a wide variety of systems have been tration on selected attributes or species groups. developed for evaluating habitats, few have been However, the broad range of information that must widely accepted or used for protected area selec- be taken into account makes evaluation more com- tion in the UK or internationally. However, one plex and subjective. One set of criteria that have been system that has been widely used is SERCON particularly frequently used are those developed by (System for Evaluating Rivers for CONservation), Ratcliffe (1977)fortheUKNatureConservation which was developed in the mid-1990s as a techni- Review (NCR). These are summarized in Table 3.3. que for assessing the conservation value of rivers in Although now over 25 years old, the NCR criteria the UK (Boonet al., 1996a,b). It aims to provide a have been widely adopted and adapted in the UK more comprehensive, rigorous, and repeatable and abroad. In particular, they formed the basis for method for conservation evaluation of rivers than the UK SSSI selection criteria (NCC, 1989). They had hitherto been available. SERCON evaluations have also been frequently used as the basis for first involve gathering all available information ecological evaluations for management planning about the physical character of a river system, purposes and many ecological impact assessments from Environment Agency River Habitat Corridor in the UK. However, Treweek (1999) points out that Surveys (Environment Agency, 2003), which then these criteria have their drawbacks; notably the guides the user into determining the size of the lack of criteria relating to recoverability or the assessment unit (the Evaluated Corridor Site). replaceability of natural resources of particular Data on other physical, chemical and biological importance when assessing impacts and mitigating features of the river corridor are then gathered for them. In addition, not all of the criteria (e.g. together from all relevant sources. Finally the col- intrinsic appeal) are measurable by using defensi- lated data are translated into a series of scores for ble, consistent and objective techniques. specific attributes on a scale of 0–5. Scores are weighted and combined to give separate indices 3.6.4 Scoring systems of conservation value for six criteria (Physical Diversity; Naturalness; Representativeness; Rarity; A frequently cited problem with ecological evalua- Species Richness; Special Features). Scores can be tions is that assessments are subjective and there- combined to give an overall assessment on an A–E fore comparisons among sites may be difficult scale, with A representing the highest-quality band. or misleading. Some multiple-criterion scoring sys- A scoring procedure may also be used for tems have therefore been established to produce selecting SSSIs on the basis of their breeding bird 3.6 Site evaluations and selection of protected areas 87

Table 3.3. The NCR criteria developed by Ratcliffe (1977) for evaluating nature conservation importance

Application / notes

Primary criteria Size Including both area of vegetation types and population sizes for individual species. Diversity Applied either as simple species richness, or by giving different weightings to species according to their ‘interest’. Rarity Applied either to habitats or to species. The latter most commonly tested by comparisons with national or county population size or distribution by 10 km squares. Naturalness Habitats that are least intensively modified by humans are generally more highly regarded. Representativeness or typicalness A measure of how well the study area represents habitats or vegetation types on a wider scale. Fragility Some habitats or species are especially vulnerable or sensitive to anthropogenic change. Those with restricted area or ranges are generally held to be more vulnerable. Secondary criteria Recorded history Can be useful in confirming that a site has been ‘important’ for some time. Sites with a long history of study may contribute significantly to our understanding of ecological processes. Potential value Relates to the likelihood that appropriate management could restore or enhance an area’s ecological value. Position in geographical or ecologi- Some areas of fairly low ‘intrinsic value’ may be more cal unit important because they form successional stages between more important areas. In addition, nationally common habitats or species might be very rare locally. Intrinsic appeal Habitats or species with public appeal promote the cause of nature conservation and can attract funds. This criterion can also be interpreted to include estimates of public use, access and amenity value.

Source: Treweek (1999). assemblage (NCC, 1989). This ‘BTO index’ is largely are primarily associated with the habitat, or which derived from a study of bird communities in differ- are particularly threatened by habitat change. All ent habitats in Britain (Fuller, 1982). The index for a species with a British population of more than one site is calculated by summing the scores across all million birds are excluded. Each species score is species that are regularly present according to a based on its British population size, such that species habitat-specific list. Each habitat list includes all with fewer than 10 pairs score 6, whereas species the characteristic species of the habitat that have a with a population of 100 000–1 000 000 pairs score 1. total British population of fewer than 1 000 pairs (at The site index may then be compared with the stated the time) and all other more abundant species that site selection threshold score, which is based on the 88 3 BIODIVERSITY EVALUATION METHODS

theoretical maximum score for each habitat for spe- Area categories and associated designation cies with more than 100 pairs. For most habitats, the criteria. threshold for qualification as an SSSI is taken as 50% * World Heritage Sites of the theoretical maximum. * Biosphere Reserves Treweek (1999) notes that there has been some * Biogenetic Sites debate over the efficiency and validity of scoring * Wild Birds Directive SPAs methods for ecological evaluations (van der Ploeg & * Habitats Directive SACs Vlijm, 1978; Gotmark et al., 1986; Usher, 1986; * Ramsar sites Anselin et al., 1989). In particular, difficulties have * National Nature Reserves arisen over the combination of quantitative and * Site of Special Scientific Interest (Wildlife & qualitative criteria. Countryside Act, CROW Act, Nature Conservation As in the examples described above, weighting is (Scotland) Act) often used to convert different systems of measure- * Local Nature Reserves ment to common formats and to increase the influ- * Wildlife Sites ence of criteria related to particularly important ecological factors. However, there is rarely any biolo- The background to these designations and, where gical rationale for weightings. For example, there is appropriate, their selection criteria are provided no clear basis for deciding that birds with British below. populations of 1–10 pairs should be given a weighting six times that of a species with a population of 3.7.1 World Heritage Sites 100 000 – 1, 000 000 pairs. Weightings therefore often tend to be arbitrary and based on the subjective World Heritage Sites are areas of global natural opinion of a few experts. To solve this problem some and/or cultural significance, and are nominated methods use consultation approaches to provide by the state within which they are situated. The weighting values. For example, the Environmental nominations are then considered by a World Evaluation System (Dee et al., 1973) uses a combined Heritage Committee of Party States. Sites that are scoring and weighting method that attempts to com- accepted are placed on the World Heritage List. bine scientific measurements of ‘value function’ World Heritage Sites must have strict legal protec- with selected indicator variables with weightings tion and any management of the site must ensure based on values allocated by members of the public that this continues. Further information on the chosen to represent relevant interest groups. Convention and a list of World Heritage Sites can When scoring systems are used they should be found at http://whc.unesco.org/nwhc/pages/ ensure that all criteria and weightings are expli- home/pages/homepage.htm. citly defined. Care should also be taken to ensure that the use of single, numerical indices based on 3.7.2 Biosphere Reserves combined scoring and weighting systems does not create a false impression of precision and conceal Biosphere Reserves represent globally significant uncertainties in the underlying evaluation data. examples of biomes (biological communities) for both terrestrial and coastal environments. They 3.7 SITE CONSERVATION DESIGNATIONS have particular value as benchmarks or standards for the measurement of long-term changes in the As indicated in Figure 3.1, any evaluation of a site’s biosphere as a whole. They were devised by conservation priority should establish its protected UNESCO under Project No. 8 of their Man and the area status and, whether or not it is designated as Biosphere (MAB) programme, and were launched such, assess its compliance with appropriate desig- in 1970. Criteria and guidelines for selection of nation criteria. Ecological evaluations in the UK sites were produced by a UNESCO task force in should take into account the following Protected 1974. Although Biosphere Reserves are not always 3.7 Site conservation designations 89

statutorily protected areas, all British sites are also of the Directive) or areas important for the con- National Nature Reserves. Further information on tinued well-being or survival of selected non-bird the MAB Programme and a list of Biosphere species (listed in Annex II) in a European context. Reserves can be found at http://www.unesco.org/ The process for the selection and designation of mab/index.htm. SACs is set out in Article 4 and its application in the UK is summarised in McLeod et al. (2002). SACs 3.7.3 Biogenetic Reserves are identified, initially as Sites of Community Importance (SCIs), by a two-stage process accord- In 1973, the European Ministerial Conference on ing to criteria provided principally in Annex III of the Environment recommended that a European the Directive. Sites that are adopted by the network of reserves to conserve representative Commission as SCIs must then be designated by examples of European flora, fauna and natural the member state as SACs as soon as possible, and areas be established. Their selection is generally at the latest within six years. based on two criteria. Stage 1 is an assessment of the relative importance of sites containing examples of the individual * Their value in terms of nature conservation: they Annex I habitat types and Annex II species in each must contain specimens of flora or fauna that are member state, against the following summarised typical, unique, rare or endangered. Annex III criteria: * The effectiveness of their protective status: this must be sufficient to ensure the long-term conser- * Habitats: vation or management of a site according to the (a) degree of representativeness; objectives set, as defined in Council of Europe (b) area; Resolution (76) 17. (c) degree of conservation of habitat structure and functions and restoration possibilities; and All sites in the UK are existing Sites of Special (d) global assessment of conservation value (i.e. an Scientific Interest (SSSIs), and most are also overall assessment, based on (a–c) above). National Nature Reserves (NNRs). * Species: (a) population size and density; 3.7.4 Special Protection Areas (SPAs) (b) degree of conservation of the features of the habitat that are important for the species, and The 1979 EC Directive on the Conservation of Wild restoration possibilities; Birds requires member states to take conservation (c) degree of isolation of the population in rela- measures particularly for certain rare or vulnerable tion to the species’ natural range; and species and for regularly occurring migratory species (d) global assessment of conservation value (i.e. of bird. In part this is achieved through the designa- an overall assessment, based on (a–c) above). tion of statutory Special Protection Areas (SPAs) by the UK government on the advice of the statutory con- Further guidance on the assessment of the Annex servation agencies. All SPAs, apart from those that are III Stage 1 criteria is given in the EC guidance docu- proposed for designation at sea, have first to be noti- ment for the Natura 2000 Standard Data Form fied as Sites of Special Scientific Interest (SSSIs). (European Commission DGXI, 1995). Further information on SPA designation proce- The global assessment referred to in the Annex III dures and criteria is provided in Chapter 24. criteria is an assessment of the overall value of the site for the conservation of the relevant Annex I habitat or 3.7.5 Special Areas of Conservation (SACs) Annex II species. Particular attention is paid to the global assessment as an overall index of a site’s con- SACs are designated under the EU Habitats servation value. Following the European Commission Directive and are defined as areas with outstanding DGXI (1995) guidance, sites are graded A, B or C, examples of selected habitat types (listed in Annex I which in the UK has been interpreted as follows. 90 3 BIODIVERSITY EVALUATION METHODS

(A) Sites holding outstanding examples of the habi- need to be taken into account in assessments of tat or populations of the species in a European sites against the Annex III criteria. These include: context. 1. restrictions on the site selection obligations in (B) Sites holding excellent stands of the habitat, or respect of widely dispersed and aquatic species populations of the species significantly above the (Article 4.1); threshold for SSSI or ASSI4 notification but of 2. the requirement to contribute towards the main- somewhat lower value than grade A sites. tenance of Favourable Conservation Status (C) Examples of the habitat or populations of the (Article 2.2 and Article 3.1); and species that are of at least national interest (i.e. 3. the obligation on each Member State to select a usually above the threshold for SSSI or ASSI series of sites that reflects the proportion of the notification on terrestrial sites) but not signifi- EU resource of a given habitat or species within cantly above this. These habitats or species are their national territory (Article 3.2). not the primary reason for SACs being selected. Further selection principles and guidance on the Although there is a distinction between the princi- interpretation of the Annex III Stage 1 criteria pal features for which sites have been selected were produced at a meeting between Member (those graded A or B) and those that are only of States of the Atlantic Biogeographical region and secondary interest (those graded C), it is important the European Commission in 1994 (Hopkins & to note that all three grades are qualifying SAC Buck, 1995), as follows. interest features and hence all such sites are afforded protection at the European level. Provision of information Stage 2, which is also known as the ‘moderation’ Acknowledging that the quality and extent of infor- stage, is an assessment of the overall importance of mation about habitat types and species varies within the sites in the context of the appropriate biogeo- the Region, Member States will provide information graphical region and the EU as a whole. All the sites to the Commission in the Natura 2000 data entry identified by member states in Stage 1 which conform using the best scientific information available tain Priority Habitat types and/or Priority Species at the time according to the format agreed by the are adopted as SCIs. Other sites listed by Member Habitats Committee. States are assessed in relation to their contribution Balancing the national lists to maintaining or re-establishing, at a Favourable 1. Acknowledging that outstanding single interest Conservation Status, a natural habitat in Annex I or sites in terms of quality, extent or range make a species in Annex II and/or to the coherence of an important contribution to the Natura 2000 Natura 2000 according to the following sum- network, special emphasis will be given to identi- marised Annex III criteria. fying and delimiting sites containing complexes * the relative value of the site at a national level; of interests on Annexes I and II as valuable ecolo- * the relationship of the site to migration routes; gical functional units. * the total area of the site; 2. Member States will give significant additional * the diversity of habitats and species present on the emphasis in number and area to sites containing site; and priority habitat types and species. * the overall quality of the site in the context of the 3. In considering the degree of representativeness of biogeographical region and/or the European Union. Annex I habitat types on individual sites, Member States will take account of the best examples in The text of the Directive also includes other site extent and quality of the main type (which is most selection requirements or qualifications and these characteristic of the Member State) and its main variants, having regard to geographical range. 4 Areas of Special Scientific Interest as designated in Northern 4. Acknowledging that sites containing Annex I habi- Ireland. tat types and Annex II species at the centre of their 3.7 Site conservation designations 91

range will make an important contribution to been carried out in the UK by expert judgement Natura 2000, Member States will take responsibil- (McLeod et al., 2002),whichisinaccordancewith ity for proposing sites containing habitats and spe- the European Commission view that ‘best expert cies that are particularly rare in that Member State, judgement is an appropriate means of ranking sites’ with a view to preserving the range. (European Commission DGXI, 1995). 5. It is acknowledged that certain habitat types This does, however, mean that it is difficult for and species listed in Annexes I and II are relatively others outside the expert group of assessors to common and extensive in certain Member States. establish whether or not a particular site should These Member States will have particular respon- qualify as an SAC. Evaluations of sites with respect sibility for proposing a proportion of the resource to their potential qualification as SACs can there- that is sufficient to contribute significantly to the fore only be judged against the general principles maintenance of the habitat types and species at a described above, their interpretation in the UK (as favourable conservation status. documented in McLeod et al. 2002) and the prece- 6. Where Annex II species’ populations are too small to dent set by sites that have been proposed as candi- be naturally viable, or where the species occur only date SACs (i.e. SCIs). as vagrants or reintroductions, Member States may All Annex I habitats and Annex II species consid- exclude them from consideration for site selection. ered to be of European importance that occur in 7. Artificial areas need not be excluded from site candidate SACs are identified as qualifying fea- selection if they have spontaneously given rise to tures. However, habitat fragments, small popula- Annex I habitat types or host Annex II species and if tions of species, and habitats and species occurring it is considered that they have exceptional value. outside their natural range are generally treated as ‘non-significant presences’. Although these habi- Defining boundaries tats and species are listed on the Natura 2000 stan- It is acknowledged that different Member States will dard data forms, they do not require conservation have different approaches to the definition of bound- objectives and are not protected under the aries (e.g. the inclusion of buffer zones within the site), Directive (as stated in the EC guidance document according to the habitat type or species concerned and Managing Natura 2000 sites (European Commission, the legal and management measures necessary to pro- 2000)). In the UK, the criteria and associated thresh- tect and extend the landscape context. olds used for SSSI selection have generally been used to distinguish between non-significant pre- A summary list of the selection criteria and addi- sences and qualifying interest features. tional principles used for site selection in the UK For further information on the SAC selection pro- are shown in Table 3.4. cess see McLeod et al. (2002) and www.jncc.gov.uk/ The various Annex III criteria and additional guide- ProtectedSites/SACselection/default.htm. This site lines listed above are principles that should be taken also includes up-to-date details of candidate SACs into account when assessing sites for potential inclu- and the Annex I habitats and Annex II species sion in the SAC network. They do not include quali- represented within them. tative thresholds or standards against which site attributes (e.g. area) can be measured. Measurable thresholds could be set for some criteria, such as 3.7.6 The Convention on Wetlands area, but SAC selection requires an assessment of (Ramsar Convention) multiple criteria, many of which (e.g. conservation The Convention on Wetlands of International structure and function) cannot easily be quantified. Importance especially as Waterfowl Habitat, more There is also no straightforward or non-arbitrary way popularly known as the ‘Ramsar Convention’, was of combining and weighting the relative importance the first of the modern global intergovernmental of the various criteria. The assessment of sites against treaties on conservation and wise use of natural the criteria and principles in Table 3.4 has therefore resources, and came into force in 1975. Compared 92 3 BIODIVERSITY EVALUATION METHODS

Table 3.4. Summary of criteria and additional principles used for SAC selection in the UK

Reference

Site assessment criteria: Annex II species (i) Representativeness Annex III Stage 1A(a); Article 1e; Conclusions of 1994 Atlantic Biogeographical Region Meeting (para. 4). (ii) Relative surface area of habitat Annex III Stage 1A(b); Article 1e; Conclusions of 1994 Atlantic Biogeographical Region Meeting (para. 4). (iii) Conservation of structure and function Annex III Stage 1A(c); Article 1e. (iv) Global assessment Annex III Stage 1A(d). Site assessment criteria: Annex II species (v) Proportion of UK population Annex III Stage 1B(a); Article 1l; Conclusions of 1994 Atlantic Biogeographical Region Meeting (para. 7). (vi) Conservation of features important for Annex III Stage 1B(b); Article 1i. species survival (vii) Isolation of species populations Annex III Stage 1B(c); Conclusions of 1994 Atlantic Biogeographical Region Meeting (para. 7). (viii) Global assessment Annex III Stage 1B(d). Additional principles (ix) Priority/non-priority status Annex III Stage 1D; Article 1d; Conclusions of 1994 Atlantic Biogeographical Region Meeting (para. 3). (x) Geographical range Article 1e. (xi) Special UK responsibilities Article 3.2; Conclusions of 1994 Atlantic Biogeographical Region (para. 6). (xii) Multiple interest Annex III Stage 2.2(d); Conclusions of 1994 Atlantic Biogeographical Region Meeting (para. 2). (xiii) Rarity Conclusions of 1994 Atlantic Biogeographical Region Meeting (para. 5).

Source: McLeod et al. (2002). with more recent ones, its provisions are relatively conservation of wetlands. The first obligation straightforward and general. The official name of under the Convention is to designate at least one the treaty reflects its original emphasis on the con- wetland for inclusion in the List of Wetlands of servation and wise use of wetlands primarily to International Importance (the ‘Ramsar List’) and provide habitat for waterbirds. Over the years, to promote its conservation. Selection for the however, the Convention has broadened its scope Ramsar List should be based on the wetland’s to cover all aspects of wetland conservation and significance in terms of ecology, botany, zoology, wise use, recognising wetlands as ecosystems that limnology or hydrology. As of March 2004 the are extremely important for biodiversity conserva- Convention had 138 Contracting Parties, who tion and for the well-being of human communities. have designated 1369 wetlands (amounting to The treaty requires Contracting Parties to desig- nearly 120 million hectares) as Ramsar sites. nate Ramsar sites, promote the wise use of wet- The Contracting Parties have adopted specific lands, establish Nature Reserves, initiate training criteria for identifying Ramsar sites, the most and undertake international co-operation in the recent of which were adopted by the 7th 3.7 Site conservation designations 93

Conference of Parties (CoP7) in 1999. However, fishes, spawning ground, nursery and/or migration path these should be used in conjunction with the on which fish stocks, either within the wetland or else- strategic Framework and Guidelines for the Future where, depend. Development of the List of Wetlands of International Importance, as also adopted by CoP7. The current criteria are listed below and can be obtained, 3.7.7 National Nature Reserves together with the Strategic Framework document, National Nature Reserves (NNRs) are nationally from the Ramsar website at www.ramsar.org. important sites that are protected and managed Group A of the Criteria. Sites containing representative, rare for wildlife. They were initially established under or unique wetland types Sections 16–29 of the National Parks and Access to Criterion 1: A wetland should be considered internation- the Countryside Act (1949) to protect the most ally important if it contains a representative, rare, or important areas of wildlife habitat and geological unique example of a natural or near-natural wetland type formations in Britain, and as places for scientific found within the appropriate biogeographic region. research. All are therefore nationally important. Group B of the Criteria. Sites of international importance for Theseprovisionswerestrengthenedbythe conserving biological diversity Wildlife & Countryside Act (1981). NNRs are either Criteria based on species and ecological communities owned or managed by the UK Statutory Agencies Criterion 2: A wetland should be considered internation- or by approved bodies such as Wildlife Trusts. ally important if it supports vulnerable, endangered, or critically endangered species or threatened ecological communities. 3.7.8 Sites of Special Scientific Interest Criterion 3: A wetland should be considered internation- ThefirstSSSIsweredesignatedunderThe ally important if it supports populations of plant and/or National Parks and Access to the Countryside Act animal species important for maintaining the biological (1949). Further SSSIs were subsequently desig- diversity of a particular biogeographic region. nated and SSSI protection measures enhanced Criterion 4: A wetland should be considered internation- under the Wildlife & Countryside Act (1981) and ally important if it supports plant and/or animal species the Wildlife & Countryside Amendment Act at a critical stage in their life cycles, or provides refuge (1985). The protection of SSSIs was further during adverse conditions. strengthened by the Nature Conservation Specific criteria based on waterbirds (Scotland) Act 2004 and, in England and Wales, by Criterion 5: A wetland should be considered internation- the Countryside and Rights of Way Act 2000. Both ally important if it regularly supports 20,000 or more Acts amend the 1981 Act’s provisions; they con- waterbirds. tain measures to increase protection of SSSIs and Criterion 6: A wetland should be considered internation- to provide additional powers for the prosecution ally important if it regularly supports 1% of the indivi- of perpetrators of wildlifecrime.Thisincludes duals in a population of one species or subspecies of enabling the conservation agencies to refuse con- waterbird. sent for damaging activities; providing new Specific criteria based on fish powers to combat neglect; increasing penalties Criterion 7: A wetland should be considered internation- for deliberate damage; a new court power to ally important if it supports a significant proportion of order restoration; improving powers to act against indigenous fish subspecies, species or families, life-history cases of third-party damage; and placing a duty on stages, species interactions and/or populations that are public bodies to further the conservation and representative of wetland benefits and/or values and enhancement of SSSIs. The new measures for thereby contributes to global biological diversity. SSSIs came into force on 30 January 2001. Criterion 8: A wetland should be considered internation- SSSIs form the basic unit of UK protected ally important if it is an important source of food for area legislation; most higher designations are 94 3 BIODIVERSITY EVALUATION METHODS

superimposed onto existing SSSIs. As legally defined, an SSSI is an areas which, in the opinion 3.7.9 Local Nature Reserves of the Nature Conservancy Council (NCC) and its A local authority can declare a site that it owns, successor bodies, is ‘of special interest by reason of leases or of which it controls the management as a any of its flora, fauna, or geological or physiogra- Local Nature Reserve (LNR) under Section 21 of the phical interest’. Coastal SSSIs do not extend beyond National Parks and Access to the Countryside Act the mean low water mark and therefore do not 1949. Sites are of local interest but not necessarily cover marine habitats. national interest. Under the Act local authorities The criteria for selection have been steadily have the power to issue bylaws to protect their refined over the years. The rationale for site selec- LNRs; although there is no obligation to manage tion was originally based primarily on habitat an LNR to any set standard, management agree- types, recognizing six major habitat ‘formations’: ments are often put in place. (1) coastlands, (2) woodlands, (3) lowland grassland, heath and scrub, (4) open water, (5) peatlands and (6) upland grassland, moor and mountaintops. In 3.7.10 Wildlife Sites each case, the best known examples were selected In an attempt to give further protection to wildlife, according to a range of criteria, as described pre- particularly at a local level, the Wildlife Trusts and viously. In the 1960s and 1970s the sites were others have designated a series of some 40 000 graded as of International, National, Regional and Wildlife Sites5 across Britain over the past 25 County importance, and the first two categories years (Everitt et al., 2002). The designation of became known as ‘key sites’. Wildlife Sites complements the protection In 1989 NCC published a standard set of afforded by statutory sites (SSSIs), primarily by Guidelines for selection of biological SSSIs (NCC, identifying other areas that have substantive wild- 1989). However, the criteria have been reviewed life interest and therefore merit some form of pro- at intervals, and refined in the light of new sur- tection. They may also play an important role in veys. The approaches and criteria used to select protecting and enhancing the value of SSSIs, by SSSIs differ considerably between habitats and maintaining wildlife corridors (and thereby linking species groups. Details of the 1989 criteria and sites) and by providing buffer areas (which may updates are therefore not discussed here, but are reduce impacts on SSSIs). provided in Parts II and III for habitats and spe- The Wildlife Sites Handbook (The Wildlife Trusts, cies, respectively. Since 1991 the Joint Nature 1997) states that: Conservation Committee (JNCC) has been the focus for the production and revision of the guide- Wildlife Sites, identified by locally-developed criteria, are the lines, which can be viewed on the following most important places for wildlife outside legally protected JNCC webpage: http://www.jncc.gov.uk/Publications/ land such as SSSIs and ASSIs. sssi/sssi_content.htm. The DETR Local Sites Review Group defined the As described previously, the condition of SSSIs purpose of Wildlife Sites6 in March 2000 as follows: in the UK is monitored under a Common Standards The series of non-statutory Wildlife Sites seek to ensure, in the Monitoring (CSM) framework agreed between the public interest, the conservation, maintenance and enhance- UK statutory conservation agencies and the JNCC ment of species, habitats, geological and geomorphological (JNCC, 1998). The key element of CSM is that the condition of each site is assessed with respect to site-specific conservation objectives for the inter- 5 The term ‘Wildlife Sites’ is used here in accordance with est feature(s) for which the site was notified or, in national recommendations of the Wildlife Trusts and equates to County Wildlife Sites, Local Wildlife Sites, Sites of County the case of SPAs, cSACs (Natura 2000 sites) and Biological Importance, Sites of Nature Conservation Ramsar sites, the features for which the site was Importance (SINCs) and other similar terms. designated. 6 Originally referred to as Local Sites by the Group. 3.8 Site evaluations for management planning 95

features of substantive nature conservation value. Wildlife habitats. This is often by setting a threshold for Site systems should select all areas of substantive value richness of listed indicator species (i.e. characteristic including both the most important and the most distinctive species of the habitat that are associated with habi- species, habitats, geological and geomorphological features tats that are considered to be of high ecological within a national, regional and local context. Sites within quality). Some criteria systems allocate scores to the series may also have an important role in contributing to the indicator species to reflect the quality of the the public enjoyment of nature conservation. habitat with which they are associated, and/or the conservation importance of the indicator species. Wildlife Sites are seen as complementary to However, it is not always clear how these scores SSSIs, while differing in two key respects. are set. Habitat quality may also be defined by physical or chemical properties or features, such as * Wildlife Sites are not statutorily designated, but water quality, or the presence of riffle and pool many receive statutory protection through the systems on rivers. The advantage of using such cri- planning system. teria is that they can be applied where comprehen- * The Wildlife Site system aims to select all sites that sive species data are unavailable. However, they are meet the given selection criteria, not just a sample indirect measures of wildlife value and should thereof these sites. fore be based on good scientific evidence of associa- It has been recognised by the Wildlife Trusts and tions between the features and biodiversity value. DETR (now DEFRA) that a wide range of approaches Species-based criteria for Wildlife Sites tend to and criteria have been used to identify Wildlife Sites. be simpler, with sites qualifying if they are species- For example, an assessment of Wildlife Site identifica- rich, or if they hold viable or significant population systems found that although some 68% used tions of particular species of conservation impor- quantifiable written criteria, 7% selected sites on pro- tance, sometimes referred to as notable species. fessional judgements alone (Everitt et al., 2002). In Such notable species typically include species that most cases Wildlife Site criteria are based on the are protected under the Wildlife & Countryside Ratcliffe (1977) criteria, or in some cases adapted Act, the Wild Birds Directive or the Habitats SSSI criteria (NCC, 1989). These criteria are typically Directive, or listed as a UK BAP Priority species, or used to review habitat types in each county and to nationally rare, or scarce or rare at a county level. identify those that are of substantive value and require Evaluations of particular sites with respect to conservation. Criteria are then listed which define county Wildlife Site standards need to be made in habitat types that qualify as Wildlife Sites. These may relation to the specific criteria for the county in be very simple, e.g. ‘semi-improved grasslands which question. These can normally be readily obtained retain a significant element of unimproved grassland’. from the appropriate Wildlife Trust. However, most criteria provide some form of quantity threshold for each habitat, sometimes in relation to 3.8 SITE EVALUATIONS FOR NVC communities, e.g. ‘neutral grasslands supporting MANAGEMENT PLANNING good examples of at least 0.2 ha in size (either in a block or as a number of smaller areas) of one of the An ecological evaluation is usually an essential following NVC communities: (i) MG4 (Meadow Foxtail component of any site management plan, as this – Great Burnet flood meadow); (ii) MG5 (Crested Dog’s- identifies, or confirms (if a prior evaluation was tail–CommonKnapweedmeadowandpasture)’. conducted), the VECs, or features of interest, that However, one of the limitations of such criteria is are present and assesses their overall importance. that they do not define ‘significant elements’ or This assessment forms the basis for setting the over- ‘good examples’, and this can lead to inconsisten- all objectives for the site and conservation objec- cies in designation and difficulties with recording tives for each feature, the most important function justifications for designation. More sophisticated of the management planning process. As stated in criteria therefore also define quality thresholds for the Ramsar Management Planning Guidelines: 96 3 BIODIVERSITY EVALUATION METHODS

It is essential that management objectives be defined of significance of the impact on these species. The for each important feature of the ecological charac- protection afforded to legally designated sites is in ter of the site and for all other important features some cases specified with respect to ecological related to the functions and values of the site, impacts (e.g. SACs). In these instances, legal and including socio-economic, cultural and educational other guidance should be followed to determine values. In other words, those responsible for devel- whether a proposal will cause any contravention oping the management plan must be clear about of legal status or protection, or have a significant what they are trying to achieve. effect on the integrity of a system, resource or feature. However, more often the requirements A variety of formats and structures have been relating to legally protected sites are not so clear- developed and adopted for site management plan- cut, as the law enables decision-makers to permit ning purposes, but many of these are similar and development on such sites if a good case can be recommend the Ratcliffe (1977) criteria as a basis made or where impacts can be successfully miti- for evaluations, e.g. Ramsar Management Planning gated or compensated. To inform this decision- Guidelines (Ramsar Bureau, 2002), the RSPB making process, it is therefore necessary to demon- (Hirons et al., 1995) and the Countryside Council strate the degree of significance of impacts. for Wales (CCW, 1996). Further information on The second purpose is to identify, document and ecological evaluations for management planning quantify as far as possible all potentially valuable is provided in these publications. ecological components (VECs) that may be affected by the development. VECs should include those that 3.9 SITE EVALUATIONS FOR may be affected by off-site impacts such as those ENVIRONMENTAL IMPACT from emissions or effluents, waste material dump- ASSESSMENTS (EIAs) ing, production of material to be used on site, road construction, water supplies and building material. Biodiversity evaluations for an EIA can be consid- Thus it is essential that all species of conservation ered to have two purposes. The first is to establish concern (see Section 3.5), important habitats (3.6), whether a proposed development will have any designated sites (3.7) and other potential VECs are legal biodiversity protection requirements. This identified within an appropriate zone of potential requirement applies to all developments that impact for the species or habitat in question. For could affect legally protected sites (e.g. SSSIs), habi- example, a zone of impact for an area of heathland tats (e.g. ancient hedgerows), species (i.e. those pro- that may suffer from atmospheric pollution from a tected under the Wildlife & Countryside Act), or proposed road development may be much larger other biological features (e.g. individual trees), irre- than, and entirely separate from, the road footprint. spective of the size, scale or location of the devel- Potential impacts should first be identified as opment. It is also worth noting that legal part of a scoping exercise, involving consultations protection does not necessarily reflect biodiversity with interested parties (e.g. statutory conservation value (e.g. Badgers Meles meles under the 1992 agencies and local conservation NGOs), interrogat- Protection of Badgers Act, Foxes Vulpes vulpes and ing biological records centres, an appraisal of exist- other mammals under the Wild Mammals ing information and a preliminary site visit by Protection Act, trees protected under Tree experienced ecologists to identify the main habi- Preservation Orders and hedges protected under tats and species groups that are present. This the Hedgerow Regulations 1997). should then be followed up by full surveys of appro- With respect to legal protection of species, the priate groups to verify and quantify as necessary EIA must set out what steps will be taken to ensure the presence of VECs identified in the scoping exer- that the law is not contravened. In this sense, the cise. Further information on these aspects of the results of the assessment must be ‘absolute’: there EIA process can be found in PPG9, the UK govern- is no requirement for an assessment of the degree ment’s planning policy guidance on nature 3.9 Environmental Impact Assessments 97

conservation currently being reviewed as Strategic co-operation with the Department for Transport. Planning Guidance (www.defra.gov.uk). This approach is used to assess which biodiversity VECs (termed ‘features’ in GOMMMS) matter, why 3.9.1 EIA evaluation criteria they are important now and how that may change over time in the absence of the proposal. This pro- The collected information on each valued ecologi- vides a base level of environmental capital against cal component within its potential impact zone is which the impact of the proposal on that level of then typically assessed against a range of biodiver- capital can be appraised. VECs are categorized sity evaluation criteria, such as the Nature according to five levels of value: negligible, lower, Conservation Review (Ratcliffe, 1977) criteria medium, high and very high. However, interpreta- described above (see Section 3.6.3). However, a tion of these categories is difficult as the assessment wide range of approaches and criteria have been criteria are not clearly explained. Furthermore, developed and used, some of which are reviewed there are insufficient categories to allow for distinc- by English Nature (1994), DoE (1995b), Treweek tion of biodiversity components of regional or local (1999) and Byron (2000). values. This results in rather subjective broad-brush One important strategic-level appraisal frame- assessments that can be acceptable for initial strate- work in the UK is contained within the New gic assessments but are inappropriate for EIAs. Approach to Appraisal (NATA) developed by the Nevertheless, the approach can be used as a basis Department for Transport and the Regions (DETR, for a more detailed and clearly defined assessment 1998). This was initially formulated to provide a framework, as for example outlined in Table 3.5, clear and open framework for the appraisal and where VECs are classified into six categories from prioritisation of trunk road investment proposals. Parish/Neighbourhood Importance to International Subsequently the NATA approach has been further Importance. As with the application of other frame- developed into Guidance on the Methodology for Multi- works, where a VEC can be valued at a number of Modal Studies (GOMMMS) for use in general transport levels, the highest value should be used. planning (DETR, 2000). The GOMMMS approach Use of this framework will unavoidably require continues to be seen by the Department for some decisions to be made by judgement, for exam- Transport as the primary source of guidance for ple on what constitutes a viable area of habitat and the development and appraisal of strategies and significant populations etc. These decisions should plans for surface transport. In 2003 the advice be made by informed expert judgement, based on originally set out in GOMMMS and its key the best available data and in close consultation supporting documents was fully incorporated with statutory conservation bodies and other rele- into the Transport Analysis Guidance (TAG) website vant consultees. Further guidance may also be (www.webtag.org.uk). obtained from The Institute of Ecology and The approach has four stages: Environmental Management (IEEM) guidelines for ecological assessment (www.ieem.org.uk) (currently * Stage 1: Describing biodiversity features. under revision at time of going to press). * Stage 2: Appraisal of environmental capital. It is also important to note that a distinction * Stage 3: Appraisal of the proposal’s impact. needs to be made between significant and impor- * Stage 4: Derivation of an overall assessment score: tant populations or habitat areas. Significant popu- large/moderate/slight beneficial and adverse, lations relate to species that are in some way neutral. threatened or otherwise of conservation impor- The appraisal stage (2) uses the concept of tance and that are substantial enough to warrant defining environmental capital, which has been conservation. For example, six pairs of Hen Harrier developed by the statutory environmental bodies Circus cyaneus would be significant, but six pairs of a (Countryside Agency, English Nature, English common and widespread species such as Song Heritage and the Environment Agency) in Thrush would not; both of these species are Red 98 3 BIODIVERSITY EVALUATION METHODS

Table 3.5. A potential framework for defining the ecological value of Valued Ecosystem Components (VECs)

Level of value Examples of qualifying VECs

International * Valuable biological features within sites of international importance, i.e. World Heritage Sites, Biosphere Reserves and Biogenetic Reserves. * Designated or qualifying features within a Ramsar site or site of EU importance, i.e. designated or candidate Natura 2000 site (SAC or SPA), or features that qualify an area for such designations. * Internationally significant and viable areas of a habitat type listed in Annex I of the Habitats Directive. * Regularly occurring globally threatened species (i.e. IUCN Red Listed) or species listed on Annex I of the Bonn Convention. * Internationally important populations of a species (e.g. more than 1% of a flyway population of birds). * Nationally significant populations of an internationally important species (i.e. listed on Annex II of the Habitats Directive, or Annex I of the Birds Directive, or with an unfavourable status in Europe). * Regularly occurring populations of internationally important species that are threatened or rare in the UK or of uncertain conservation status. National * Designated or qualifying features within nationally designated sites (SSSIs, ASSIs, NNRs, Marine Nature Reserves), or features that meet the published selection criteria for national designation. * Nationally significant and viable areas of UK BAP Priority Habitats identified as requiring site protection (see HAPs). * Nationally important populations of a species (e.g more than 1% of national population for birds). * Significant populations of nationally important species, i.e. listed on Schedules 5 and 8 of the 1981 Wildlife & Countryside Act (as amended) and UK Red Data Book species (excluding scarce species) or, if not a non- Red Data Book species, listed as occurring in 15 or fewer 10 km squares in the UK. * UK BAP Priority Species requiring protection of all nationally important sites. * Any regularly occurring population of a nationally important species that is threatened or rare in the region or county. Regional (i.e. government * Regionally significant and viable areas of key habitat identified in a regions) Regional BAP. * Regionally significant and viable areas of key habitat identified as being of regional value in the appropriate English Nature Natural Area. * Regionally important populations of a species. * Significant populations of a regionally important species. * Regularly occurring, locally significant populations of species listed as being nationally scarce (i.e. which occur in 16–100 10 km squares in the UK), or in a Regional BAP or relevant Natural Area on account of their regional rarity or localisation. 3.9 Environmental Impact Assessments 99

Table 3.5. (cont)

Level of value Examples of qualifying VECs

County/ Metropolitan * Designated or qualifying features within Local Nature Reserves or Wildlife Sites, selected on county/metropolitan criteria, or features that meet the published selection criteria for designation. * Semi-natural ancient woodland greater than 0.25 ha in area. * Significant and viable areas of habitat identified in County BAPs as requiring site protection. * Species populations of county/metropolitan importance. * Significant populations of a county/metropolitan important species (i.e. listed in a County/Metropolitan Red Data Book or BAP on account of their regional rarity or localisation). * District/Borough * Biological features within Local Nature Reserves, etc., selected on District/Borough ecological criteria. * Areas of habitat identified in a sub-County (District/Borough) BAP or in the relevant Natural Area profile, and other features that are scarce within the District/Borough or that appreciably enrich the District/ Borough habitat resource. * Diverse and/or ecologically valuable hedgerow networks. * Semi-natural ancient woodland smaller than 0.25 ha in area. * Species populations of District/Borough importance. * Significant populations of a District/Borough important species (i.e. listed in a local BAP on account of their local rarity or localisation). Parish/Neighbourhood Areas of habitat considered to appreciably enrich the habitat resource within the context of the Parish or Neighbourhood, e.g. species-rich hedgerows. Valuable biological features within Local Nature Reserves selected on Parish ecological criteria.

Source: Based on draft IEEM guidelines for EIAs, currently under review at the time of going to press. Notes: See Section 3.7 for details on designations. The viability of an area of habitat is defined by NCC (1989), paragraph 2.10.3, as ‘Given that the intrinsic vegetational quality of the habitat is acceptable, its area must be big enough to be viable, in respect of the resistance of the habitat and its flora and fauna to edge effects, loss of species and colonisation by unwanted species.’ Unless defined in appropriate publications, significant numbers of species or habitat areas (internationally, nationally, etc.) should be agreed in consultation with statutory conservation agencies and other relevant consultees.

Listed in the UK (Gregory et al., 2002). Important fuligula that is more than 1% of its flyway populations are those that are sufficiently abun- population). dant to warrant conservation irrespective of the Care should also be taken in assessing the import- conservation status of the species in question ance of individual sites for species, particularly with (e.g. a wintering population of Tufted Duck Aythya regard to widespread Red List and BAP listed species. 100 3 BIODIVERSITY EVALUATION METHODS

Box 3.1 An evaluation of Valued Ecosystem mixed farmland and a small brackish lagoon. The Components (VECs) potentially affected by a development site partially overlaps with an SAC, SPA, hypothetical development SSSI and a County Wildlife Site. Example VECs are listed in the table (according to their highest ecological value), This example relates to the proposed development of a but for simplicity many are omitted, and VECs that may marina on an estuary in East Anglia, which may directly be affected by off-site impacts are not considered. HD, affect some 120 ha of mudflats, sand dunes, saltmarsh, Habitats Directive; WBD, Wild Birds Directive.

Value (see Table3.5 ) Example VECs Rationale

International 108 ha of estuary habitat Designated SAC feature (HD Annex I habitat) 80 ha mudflat Qualifying SAC feature (HD Annex I habitat) 22 ha Atlantic salt meadows Qualifying SAC feature (HD Annex I (Glauco-Puccinellietalia maritimae) habitat) Important wintering population of Designated SPA feature Wigeon Anas penelope (>2% of NW European flyway population) Petalwort Petalophyllum ralfsii Qualifying SAC feature (Annex II species) National 1.8 ha coastal lagoon SSSI Notified feature (HD Annex I habitat, but not SAC qualifying feature) Nationally important wintering Notified SSSI feature population of Lapwing Vanellus vanellus Small wintering population of WBD Annex I species, population not Short-eared Owl Asio fammeus nationally significant, but species is regionally rare Stinking Goosefoot Chenopodium Schedule 8 of Wildlife and vulvaria Countryside Act 1981 as amended 1988, Nationally vulnerable Regional Otter Lutra lutra: regular reports, HD Annex II spp, but dispersed population unknown species and population not of international or national significance, but spp rare in East England Regular breeding population of Regionally significant population of Redshank Tringa totanus Amber listed species (see Chapter 24) Small-flowered Catchfly Silene gallica Nationally scarce, UK BAP priority species and County BAP species County / 3 ha of mobile foredune and yellow Small area of degraded dunes does Metropolitan dune not conform with HD Annex I habitats or SSSI criteria; qualifies as Wildlife Site (but not designated) 3.9 Environmental Impact Assessments 101

Value (see Table3.5 ) Example VECs Rationale

0.8 ha reedbed County Wildlife Site feature Breeding Reed Bunting Emberica UK BAP Priority Species and Red List schoeniceus species but dispersed and site protection not proposed in SAP. Listed as target species in County BAP Sharp Rush Juncus acutus Nationally scarce, locally rare and diminishing Parish 200 m of ancient hedgerow, Rare habitat in parish with some mature oaks Farm pond Artificial pond, but frog spawning site. Would be an issue if lost and contained Great Crested Newt Breeding Linnet Carduelis cannabina UK BAP Priority species and Red List species but dispersed and site protection not proposed in SAP. Only breeding colony in parish

It is inappropriate to give all UK BAP Priority Species regional BAP identifies a requirement to protect all a ‘national’ level of importance within EIA evalua- populations of a particular species (where there is no tions. Instead, evaluation levels should be dependent similar recommendation in the UK BAP) each popu- on the ‘Policy and Legislation’ and ‘Site Safeguard’ lation should be considered to be of regional import- measures that are given in the BAP or corresponding ance. Similarly, if a sub-national BAP identifies the Species Action Plan (SAP) for the species in question. need to protect all populations above a certain size, Thus, species for which the national SAP recom- these populations should be considered to be of mends the safeguard of all sites are afforded national importance at the relevant scale. importance. The level of importance that is attached Some example evaluations of VECs according to to other species should then reflect the recommen- the framework and categories outlined in Table 3.5 dations in sub-national BAPs. For example, if a are presented in Box 3.1 for a hypothetical site.

Part II * Habitats

4 * Introduction to habitat evaluation

4.1 HOW TO USE THE HANDBOOK: acceptance as a cost-effective way of assessing A RECAP the quality of designated sites. Depending on the objectives of the study, the range of methods Part II of the Handbook is intended as a general- described in this chapter will be useful for different purpose source of detailed, practical information situations. on study design, sampling and analysis as well as Chapter 5 provides detailed information on the on the most commonly used methods for surveying most commonly used habitat survey and monitor- and monitoring terrestrial and freshwater habitats. ing methods. Qualitative as well as quantitative The development and successful implementation methods are included to cover situations in which of a survey and monitoring programme involves resources are limited or sophisticated methods making a series of crucial decisions. Part II of the are unnecessary. The descriptions also aim to pro- Handbook is therefore designed to provide a step- vide sufficient practical information for most of by-step guide through the process of planning and the techniques to be applied in the field. More executing a survey and monitoring programme. specialised techniques are summarised and key However, the design and implementation of a pro- sources of further information listed. Specialised gramme is not a linear process, but often involves monitoring techniques carried out in collaboration iterative steps that depend on the outcome of other with other bodies are also summarised and decisions. Because monitoring is largely defined the reader is referred to appropriate specialist by a series of surveys, the term ‘survey’ is usually documentation. also implied where the term ‘monitoring’ is used Each section on methods, dealt with fully in throughout this Handbook. The main topics covered Chapter 6, starts with a table summarising the in Part II are listed below. information covered in that section. The following points are considered:

4.2 HABITAT SURVEY AND MONITORING * the recommended uses of the method; * the efficiency of the method, i.e. the combined This chapter identifies the attributes of major quantity and quality of data produced in relation habitat types that provide an indication of their to cost and effort; condition. These should be the focus of habitat con- * the objectivity of the method; dition monitoring programmes. For each habitat a * the precision obtainable; summary table lists these attributes and provides * the likely nature of any inherent bias; cross-references to descriptions of the recommen- * the expertise and equipment required; ded methods for monitoring them (provided in * field methods; and Chapter 5). Reference should also be made to gen- * data storage and analysis. eric guidelines on defining Condition Objectives for statutory sites that are being developed by the UK Chapter 7 briefly describes monitoring methods conservation agencies (visit their websites for latest for management practices (such as grazing and information). Condition monitoring has gained burning) and other environmental processes, such

# RPS Group plc and Scottish Natural Heritage 2005. 106 4 INTRODUCTION TO HABITAT EVALUATION

Where to find it

Chapter or Topic Part Section

Planning a General monitoring theory I 1.1 monitoring Setting objectives for monitoring I 2.1 programme Selection of monitoring methods I 2.2 Designing a sampling strategy I 2.3 Reviewing a monitoring programme I 2.4 Data recording and storage I 2.5 Data analysis I 2.6 Habitat Attributes of major habitat types II 5 monitoring Habitat monitoring methods II 6 Management monitoring methods II 7 Species General species monitoring theory III 10 monitoring Species attributes and monitoring methods III 11–26 as erosion, all of which may influence the features sampling schemes, the reader should first look of interest on a site. It is important that monitoring up the habitat type that is to be monitored in programmes, where necessary, include monitoring Chapter 5. The habitat tables in each of the sections of management practices; although it is beyond the in that chapter list the appropriate methods for scope of this Handbook to deal with these in detail, monitoring each attribute of the habitat. Consult further sources of information on these subjects the relevant sections in Chapter 6, and then return are listed. to Part I to follow the remaining steps for designing When using this Handbook as a guide for select- a monitoring programme and sampling scheme ing habitat monitoring methods and designing (if the appropriate method requires it). 5 * Habitat requirements and issues

The primary purpose of this section is to identify, for programmes for habitats on designated sites, as each broad habitat type, the potential attributes that there may be additional attributes that require indicate the condition of the habitat and to recom- monitoring listed in the JNCC guidelines which mend methods that may be used for monitoring are not covered in the habitats sections in this each of these. These recommended methods are Handbook. described individually in Chapter 6,orinPartIII (species) for methods that are more often applicable to surveying and monitoring individual species. The 5.1 WOODLAND AND SCRUB section also identifies key management actions and 5.1.1 Survey and monitoring requirements other environmental factors that may have impacts and methods on the habitat and may therefore require monitoring. Finally, any specific monitoring issues (e.g. prac- Attributes for assessing habitat condition tical implementation, health and safety and the Woodlands can exist under a great range of envir- frequency of monitoring) that may influence the onmental conditions, from tree line to floodplain, design of a survey or monitoring programme in on virtually all soil and rock types, from dry rock the habitat are briefly described. Habitats have outcrops to permanently waterlogged marshland, been divided according to UK Biodiversity Action and from coastal dunes to inland mesic loams. Plan (BAP) Broad Habitat types. Based on structural Inevitably, when presenting guidance for the full similarities the methods can be applied to the full range of woodland types, there will be a large num- range of habitat types found in Europe and, indeed, ber of methodologies, some of which will be other parts of the world. required in only one woodland type. Within the UK, JNCC have recently published Woodlands also vary greatly in structure. online guidelines on Common Standards Moni- Although they are generally defined by the preva- toring. This provides guidance on setting and asses- lence of trees, the trees can vary in stature and sing conservation objectives for the range of degree of cover. For example, acid oak woodland species and habitat features which occur on UK may occur as tree-line scrub, and coastal scrub protected sites. The process is now well advanced, woodland may be no taller than a person; on the with guidance available on conservation objectives other hand, towering groves of single-stemmed and assessment methodologies for about 75% of the trees, spreading pollards from old parkland and features of designated sites. At the time of writing, multi-stemmed coppices growing out from past guidance was available for coastal, lowland grass- felling are all included in the term ‘woodlands’. land, lowland heathland, upland and woodland Furthermore, the aims of treatment vary within habitat features. Guidance on lowland wetlands any one structure, so that, for example, a formerly and freshwater habitats is being developed. coppiced stand may be re-coppiced, allowed to These guidelines are available online at www. grow naturally, or converted to wood-pasture. The jncc.gov.uk/csm/guidance/default.htmintroductory attributes that should be monitored within one and should be consulted when devising monitoring particular structure may not be appropriate for

# RPS Group plc and Scottish Natural Heritage 2005. 108 5 HABITAT REQUIREMENTS AND ISSUES

another. The implications of what is observed will * Subjective observations by an experienced obser- vary according to management intentions. ver, interpreted in terms of trends and factors. For Change within woodland varies in kind, spatial example, the adequacy of regeneration can be scale and timescale. It can be broadly classified as assessed in a single, short visit by an observer, follows: who can make experienced judgements on the opportunities for, and state of, present regenera- 1. Natural expression of the growth, mortality and tion, and on its future prospects. The results are regeneration of trees and shrubs, which changes not normally valid statistically, but assessments stand structure and composition and influences are immediate, are useful for management plan- other components of the woodland. This is ning, and help to identify issues for more detailed usually measurable over decades: significant trends investigation. are rarely detectable in less than 10 years. * Detailed, precise observation, which enables any 2. Disturbances created by natural forces or by man- change to be quantified and validated by statis- agers. These may be abrupt events (e.g. fire, blow- tical tests. This requires careful design, long-term down, felling) or slow changes (e.g. as a result of data storage and a capacity to analyse the data. It drought, change in deer culling regime), the effects thus requires substantial resources and effort, and of which will require monitoring over many years. must be carried out to a high standard. 3. Responses by ground vegetation (open-space vegetation and field layer under trees) to 1 and 2, The principal questions for most woodland stand combined with the internal dynamics of these monitoring are (i) is it regenerating? (ii) is it chan- assemblages. Response rates, and thus monitor- ging in composition? and (iii) is it changing in struc- ing frequencies, vary according to the character ture? Of these, regeneration is both the most of the changes to which the assemblages are difficult question to answer and the question most responding. often asked. Woods must regenerate to persist, but 4. Responses of fauna to 1–3; internal dynamics of regeneration is often patchy and episodic. Woods animal species and interactions; direct influences have survived even where regeneration has been on fauna, e.g. by pest management or deer hunt- absent from much of the wood for much of the ing. Rapid changes from year to year are charac- time. The more pertinent issue is whether a wood teristic, especially of small animals. Monitoring is regenerating when it should, i.e. when it would do should be an annual process, but the problem is to so naturally, or should do so under management. distinguish between long-term trends and short- Recognising when adequate regeneration is tak- term fluctuations. ing place is also problematical. The presence of 5. Changes in site condition as a consequence of seedlings and saplings does not guarantee that (i) 1–4; (ii) physical processes acting directly, and there will be recruitment to the canopy. The pre- thus factors in 1–4; (iii) long-term maturation, sence of a thicket of saplings may be no more e.g. of soils; and (iv) pollution uptake. effective in the long term than a sparse scatter: Recently proposed monitoring frameworks for there is only so much room for canopy trees. On woodland habitats (Kirby, 1994; Kupiec, 1997) average, one large oak needs to generate only one accept that anything more than a quick site inspec- other large oak in 300–500 years to sustain the tion by an experienced observer is time-consuming species and the wood. Even in natural woods, the and thus expensive. In practice, monitoring in regeneration of a particular species is likely to be woodlands is a choice of strategies: extremely irregular in space and time. Against this background the critical question is: * Recording events (i.e. abrupt changes in the status are enough individual saplings of the right mix of quo) when they occur, with their immediate con- species developing beyond the reach of grazing and sequences. The record forms a basis for assessing browsing when and where circumstances are right change at a later date. for regeneration? ‘Right’ for canopy trees would be 5.1 Woodland and scrub 109

defined by availability of canopy space, plus an the lateral spread of fertilisers from nearby fields ‘extension’ to cover advance regeneration of through drift and leaching. shade-bearing species. ‘Right’ for structure would Measurement of natural changes would be be defined by cover and stratification that normally extremely laborious, and would certainly not be allows enough light through to permit an under- cost-effective. Measurement of most soil changes storey to develop. due to forestry operations is best done directly, e.g. Regeneration relates to the continued existence flow in drainage ditches, extent of rutting and dis- and future character of the woodland. Other attri- tribution of surface disturbance during forestry butes relate to its condition. operations. Measurement of change in nutrient A description of attributes indicating the condi- status due to pollution inputs or forestry operation of woodland and scrub habitats is presented tions can be achieved by: below and summarised in Table 5.1. 1. repeated samples from the same points (i.e. the equivalent of permanent plots); and Shape and size 2. analysis of chemicals in run-off. Shape and size is a particular issue for upland woodland types, floodplain woodland and bog Of these, the latter is expensive but offers the woodland. It is rarely an issue in lowland woods, possibility of constructing nutrient budgets. The where most boundaries are sharply defined and former should be far less expensive, especially if static, but may be significant where the wood the initial observations are repeated only when abuts semi-natural non-woodland habitats. there is a need to know. Defining what counts as woodland is problematical Observations of change due to forest opera- in wood-pasture and regenerating woodland. tions should be made before and after operations. Monitoring requires delimitation of the wood- Baseline soil nutrient observations should be land boundary. This is generally straightforward in repeated on a need-to-know basis, but there is a high-definition lowland farmland, but often diffi- case for repeating them after 25 years, even if no cult in upland pastoral environments. Delimiting particular need has arisen in the meantime. woodland requires a decision on the minimum size of feature to be heeded (a fractal issue). Even on Hydrology rapidly changing boundaries, repeating observa- This is particularly important for floodplain wood- tions at intervals of 10 years would be sufficient land and bog woodland, but it can also be an issue from the point of view of the woodland. in any wood where streams, flushing zones and water tables influence condition. Monitoring Soil needs differ greatly between woodland types. Forest soils change naturally, but profile develop- In floodplain woodland, channel configuration ment is usually very slow. Erosion is rarely severe, can be tracked by a combination of aerial photo- and soil creep on slopes is very slow. Rapid change graphs and on-site observation of areas of erosion occurs very locally when trees fall over. A change in and deposition. Location of bank erosion and shoal the dominant trees and shrubs may also change deposition can be noted annually on site maps. The humus characteristics. Forest operations can also flooding regime is best followed from flow records change soils. When drainage ditches are dug, proof river managers, combined with on-site observa- file character and microtopography are altered in tion of main floods. The assessment of water qual- the immediate vicinity. Felling and extraction can ity would also normally depend on information alter natural microtopography and mobilise soil from river managers (see Section 5.10). In bog nutrients. woodland, the need is to assess water table fluctua- Pollution inputs are likely to be the major con- tion and water quality. cern at the present time. Throughout Europe there In most woods there is a need to monitor any is concern about acid rain, nitrate deposition and streams and springs that may be present. In some 110 5 HABITAT REQUIREMENTS AND ISSUES

Table 5.1. A summary of the quality attributes providing an indication of the condition of woodland habitats, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Size and shape Area of individual wood and Aerial photographs (Section 6.1.3) configuration of boundaries Phase I mapping (6.1.5) Comparison with historical maps (not described) Soil Structure Soil cores (6.2.2) Nutrient status Chemical analysis (not covered) or run-off chemistry (not covered) Hydrology Watercourse configuration Mapping Flooding regime River flow data/visual inspection Water chemistry Chemical analysis (not covered) Water table fluctuations Dipwells (6.2.1) Composition Stand pattern in managed forests: Stock mapping (6.5.1): covers all aspects * extent of old, mid- and young growth of stand pattern monitoring * extent and configuration of felling patches and canopy gaps * rotation of managed stands * stock of particular size classes * thinning extent and degree Communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition, richness and Species lists diversity Temporary plots (6.5.3) Plotless sampling (6.5.4) Structure Age class diversity Enumeration by permanent plots (6.5.2), Horizontal and vertical structural temporary plots (6.5.3), plotless sampling diversity (6.5.4), mapping individual trees (Part III, Retentions to natural death Section 15.2.4) Thinning extent and degree Deadwood: standing and fallen Enumeration (see above), measurement * volume of fallen wood and decay condition (6.5.5) * size distribution * spatial pattern Dynamics Open spaces Stock maps (6.5.1) * Extent and location Fixed-point photography (6.1.4) Aerial photography (6.1.3) 5.1 Woodland and scrub 111

Table 5.1. (cont.)

Attribute Habitat properties Monitoring technique

Seedling regeneration; composition, Enumeration (see above) number and distribution Ground vegetation condition (6.4) Renewal of coppice stools Amount and distribution of planting Provenance of planted stock and natural regeneration

forms of wet woodland (e.g. alder woods) the water method that recent recruitment can be assessed table is another important factor. One can also and prospective long-term changes in stand com- envisage the degree of flushing in slope woods position picked up. Here, too, past irregularities in becoming an issue, but it rarely if ever arises. recruitment can be identified, subject to the limita- An annual check of springs and watercourses tion that only the survivors provide information. should be sufficient to alert managers to significant Enumerations also provide an opportunity to changes, supplemented by checks after extremely record the condition of individual trees, e.g. wet periods (or major floods) and after severe crown vigour, degree of damage by squirrels, etc. droughts. More detailed hydrological monitoring The pattern of sampling determines what informa- is, however, more difficult (see Section 6.2.1). tion can be gathered on distributions of species and size classes. A regular grid of plots can give Stand extent and structure distribution information. Plotless sampling This is the core of forest monitoring, and in forests (Section 6.5.4) does not, but it can be more refined managed for timber production this links standard if samples are confined to units recognised on forestry monitoring with environmental monitor- stock maps. Transects (Section 6.4.6) give informa- ing. In such cases, two classes of observations are tion on small-scale patterns, such as groups and normally required: zonation. Plots and transects can be used to map canopy gaps; aerial photographs can also be used. 1. stock maps (Section 6.5.1), which show the patch- Rare features, e.g. pollard trees or large coppice work of stands; and stools, are best mapped individually. 2. enumerations of trees and shrubs (Sections 6.4 Photographs record a great deal of detail in a and 6.5), which show composition and stand non-quantitative and unedited fashion. They are structure. best for giving a general impression of change, Stock maps partition the stands according to age demonstrating change to others and monitoring of canopy and main species, show felling coupes, features that were not initially thought to be and give information on patch size and configura- important. Fixed-point photographs (Section 6.1.4) tion. They are simplifications that convey whole- can be a cheap but effective method of revealing site structure and work well in woods managed on the main features of long-term change, provided a moderate- to large-scale felling pattern and with that enough care is taken to select a representative coupe shapes. They show little or nothing of verti- set of points and to record location and conditions cal stand structure, or of fine detail. accurately. Enumerations of individual trees and shrubs Changes can be identified by repeating an obser- give information on size-class distributions, stand vation. Permanent plots and transects have to be composition and how these are related. It is by this marked and re-found. In return for the extra effort 112 5 HABITAT REQUIREMENTS AND ISSUES

involved, they can provide detailed insights into also intervene, and you cannot assume that the stand dynamics, population changes and the fate plan will be carried out to the letter. An annual of individual trees. Repeated enumerations in tem- record of management operations that affect the porary plots give information on net change, stock map (and major natural events) should be but the fate of individuals is not known; this made, i.e. the stock map should be updated restricts the analysis of factors underlying change. annually, and old stock maps should be retained However, it is not essential to have permanent as part of the record. plots unless it is necessary to track the progress of Change in stands is generally slow, but rapid individual trees. A well-structured temporary sam- change may occur unpredictably. In undisturbed ple will generally be sufficient to monitor the pro- stands general records need not be repeated at inter- gress of a population. vals of less than 10 years. When stand-changing In a managed semi-natural woodland it may be events occur (e.g. windthrow, drought, disease), a sufficient to generate a stock map. Rare and special record should be made immediately after the event. features can be mapped on to a stock map base. If such an event takes place, it would be advanta- Age-class distribution can be expressed in terms geous to have observations shortly before the event, of areas. If particular species are dominant in so routine observations should not be too far apart. parts of a wood, age class can also be expressed in The optimal interval would probably be routine gen- terms of species. Patch size and shape can be mea- eral recording every 10 years, or thereabouts, com- sured from maps. This approach is appropriate in bined with small subsampling at 5 year intervals and woods in which: recording immediately after a major disturbance. 1. felling is done in well-defined patches; and Regeneration 2. operations within a patch are relatively simple, Seedlings and saplings are part of both the stand such as clear-cut felling. and the ground vegetation. They are considered In semi-natural woods managed on an irregular separately because regeneration is a key indicator basis, e.g. group felling or irregular thinning with- of the state of a wood. out clear felling, enumerations should form the Estimates of seedling density and distribution basis of monitoring. Likewise, in non-intervention rarely provide useful information on the progress woodland, it will be necessary to enumerate and/or of regeneration. However, if regeneration of a par- record permanent or temporary plots. Canopy gaps ticular species is failing, observation of seedlings should be defined and delimited. may indicate whether the failure is in seed produc- Monitoring dead wood is important, especially tion or post-germination survival. In woods in because of its biodiversity value to fungi, inverte- which regeneration is not taking place, a seedling brates, birds, etc. Dead wood can be partly recorded survey will indicate the potential. However, obser- in ordinary enumerations, i.e. snags and stumps. vations over several years will be necessary to allow Other dead wood elements (e.g. fallen wood, dead for the ‘mast year’ phenomenon (years in which branches on living trees, decay columns) have to be trees produce an unusually large volume of seed). separately recorded. The transect method (Section Estimates of the distribution and density of 6.5.5) permits this for patches of 1 ha or more. A small saplings (less than 1.3 m in height) are far quicker alternative, based on indices for each dead more meaningful. Saplings are established indivi- wood element, is promising, but has not been ade- duals that have the capacity to grow into trees, but quately tested (Peterken, 1996). One can also map almost all fail to become trees because they are the categorical quantities of dead wood on a killed by competition, browsing, breakage, defined grid for the site. drought, etc. It is quite possible for a substantial Change in features recorded on stock maps population of saplings to be permanently present, (Section 6.5.1) is determined mainly by the plan of yet for no regeneration to be occurring, i.e. there is management, but catastrophic natural events may no recruitment to the canopy. 5.1 Woodland and scrub 113

Large saplings (taller than 1.3 m) should be moni- grow, spread, decay and die. Variations in soil tored as part of stand enumeration. moisture content due to periods of heavy rain or Permanent plots in which individual saplings drought generate perpetual adjustments in the bal- are mapped allow the population dynamics of ance between species. Superimposed on these regeneration to be understood. It is possible to changes are responses to changes in the structure follow the fate of individuals (merely counting the and composition of the stand, both natural and due number of seedlings present in a plot may conceal to management. the fact that none of them lives longer than three The ground vegetation component of National years). The ability to find the remains of saplings Vegetation Classification (NVC) types may change that were recorded on a previous occasion com- (e.g. as a result of fire or grazing), but site character- monly allows population turnover to be deter- istics are the main control. If a different tree species mined and the cause of death to be identified. colonises the wood, there could be a change of NVC This is only possible if monitoring occurs regularly. type without any change in the species composition If more than 5 years elapse between samples, the of the ground flora. However, a map of NVC types chances are that the remains of saplings will not has value in monitoring as a basis for stratifying be visible. sample points. Exact delineation of boundaries Temporary plots and plotless sampling allow the between types is not necessary to design the pattern density, composition and distribution of seedlings of sampling, and will rarely be sufficiently exact to and saplings to be quantified, and to demonstrate detect slight shifts in boundaries. changes from previous observations, but the inter- Change in ground vegetation diversity happens pretation of these observations may be equivocal. at various scales. Change is inevitable at the scale of In general, if there is a need to observe small sap- 1m2, and species turnover can be high in 10 m Â 10 m lings (i.e. those missed by ordinary stand enumera- plots (more than 40% of species over 15–20 years). tions), it should be done by a method that allows Change at larger scales is less, and change at the the processes to be understood, i.e. by recording at whole-site scale (i.e. colonisation and extinction) is the level of individuals in permanent plots. rare. Any assessment of ground vegetation change If regeneration takes the form of regrowth from must take account of scale. stumps, the simplest and most useful measure of Whole-site monitoring requires a species list for any individual would be the height above ground of the site. This will include those localised species not the tallest sprout. In many cases, such regrowth detected in the aggregate of sample plots. The total exceeds 1.3 m in the first or second season, and number of species in all sample plots does, however, would thus be recorded as part of ordinary stand provide an alternative measure of whole-site species enumeration. In woods in which regeneration richness. Sample plots provide an opportunity to takes the form of planting, one assumes that the measure small-scale change and vegetation height, manager will keep a record of what is planted and to map distributions, and to take fixed-point photo- where. If saplings are protected by tubes or sticks, it graphs. The capacity to map changes may be import- is simple to record their survival and growth. ant if there is reason to suspect patchy change, e.g. If one is observing naturally regenerating indivi- due to lateral fertiliser drift. duals in permanent plots, observations should be Sample plot recording of ground flora is nor- at least annual. The optimum is probably two mally worth repeating at 10 year intervals, so that observations each year, at the start of the growing a reasonably recent record is available for compari- season and at its end. sons when a substantial change is suspected, e.g. after change in grazing pressure. Ground vegetation Ground vegetation changes continually. In addi- Open spaces tion to the seasonal cycle, the small-scale pattern These are the ‘permanent’ open spaces, i.e. mainly of species changes from year to year as individuals glades in upland woods and rides in lowland 114 5 HABITAT REQUIREMENTS AND ISSUES

woods. For some species groups, the biodiversity of there is a possibility that the most recent record of open spaces may exceed that of tree-covered condition before a major blowdown (which is ground. Most take the form of grassland and tall unpredictable) will be 19 years before the event. herb communities (Section 5.4). A map showing the Accordingly, the best tactic is to repeat records at exact configuration of ‘permanent’ open spaces is suitable intervals for each attribute, or after major required as a baseline, which is part of – or a sup- events. Subsamples can be recorded between plement to – the stock map. The degree of shading main recordings, or to determine whether a full of rides and boundary characteristics should also re-recording is worthwhile. be recorded. Recording of ground vegetation should be Newly created permanent open spaces should be undertaken in the growing season. Strong seasonal recorded as part of the annual updating of a stock changes require that plots be recorded during a map. Boundary conditions may be best recorded by particular season. Lists should be compiled at two fixed-point photography at 5 year intervals. points in the season, to cover spring and summer aspects. Enumeration of stand condition is best Management requirements and external impacts avoided during the peak of the growing season Management and external impacts that require (May to July). Winter recording is best for stand monitoring include forestry practices and natural structure. Thus, there can be a degree of comple- disturbances, grazing and browsing intensity, fire, mentarity in the annual monitoring programme. pollution (particularly atmospheric inputs) and Compartmentalisation of monitoring may be public access and disturbance. desirable in larger and heterogeneous woods. Forestry practices are typically monitored by Different monitoring programmes may be neces- stock maps. Stock maps can also record large-scale sary in areas undergoing different treatments (i.e. natural disturbances; small-scale impacts can be in what foresters used to call working circles). detected by routine enumerations. See Chapter 7 Care should be taken to ensure that the monitor- for more details on monitoring other impacts. ing programme does not itself affect the condition of the wood. Recording of permanent plots (includ- 5.1.2 Specific issues affecting the ing transects) can damage vegetation and alter the monitoring of the habitat browsing patterns of deer. Marker posts can influence both deer and forestry contractors. Woodlands generally change slowly, but major rapid change can happen as a result of natural events, changes in grazing/browsing regimes, and 5.2 LOWLAND WOOD-PASTURES AND forestry operations. Annual recording is very rarely PARKLAND justified, except at the level of an annual inspec- 5.2.1 Survey and monitoring requirements tion. Rather, monitoring is most efficiently under- and methods taken by: Attributes for assessing habitat condition 1. establishing baselines; and Some wood-pastures require separate treatment 2. recording events. from woodlands. Those that do are defined as con- Baselines describe the condition at a particular sisting of an open scatter of trees in a matrix of date. The record can be repeated when there is a pasture (i.e. parkland), and also include very open need to assess change. Rigid adherence to a prede- parts of mature woodlands (pine (Pinus spp.) woods, termined recording interval is rarely necessary. oak (Quercus spp.) woods and birch (Betula spp.) However, if the interval between recordings is woods). Although many woodlands sustain such a large, there is an increased risk that no recent high pressure of grazing and browsing that they record will be available before a major change. mayeventuallybecomewood-pastures,theyshould For example, with a recording interval of 20 years, be regarded as woodland for present purposes. 5.2 Wood-pastures and parkland 115

The trees in parklands are generally large and/or saplings. Monitoring regeneration can thus be a old. They are isolated from each other or distrib- matter of recording the survival of marked samples uted in small groups. Either way, the trees should be of individuals. regarded as individuals and recorded as such. The In open woodlands, which have effectively been ground vegetation can be regarded as grassland or pastures with trees for at least decades, the aim heathland (see Sections 5.4 and 5.6, respectively). may be to regenerate woodland by removal of, or A description of attributes indicating the condition reduction in, grazing animals. The initial stages of of wood-pasture and parkland habitats is presented this process can be successfully monitored by fixed below and summarised in Table 5.2. quadrats or transects (Section 6.5.2). An annual inspection is desirable, preferably at Shape and size the end of the growing season, or before animals The extent of parkland is extremely difficult to mea- are admitted to pasture. Height and growth of sure, principally because its boundaries are vague. important individuals may be worth recording Boundaries may be roughly delimited on a map, but annually but, as growth during each of the past 5 a precise delimitation requires decisions on mini- years or so can generally be assessed by inspection mum density of trees and minimum mappable of individuals, any more general recording is only patch size. Change is better assessed in terms of worthwhile at this interval. Likewise, an annual individual trees. Patches of closed woodland within inspection is desirable during the early stages of wood-pastures should be monitored as woodland. restoration of grazed woodland.

Stands Management requirements and external impacts The special feature of monitoring parkland is the Management and external impacts that require treatment of the stand as a population of individual monitoring are similar to those for woodland and trees. Change can be quantified in terms of num- scrub and include forestry practices and natural bers and distribution of trees of a particular class. disturbances, grazing and browsing intensity, fire, Each tree can be mapped and numbered, aided by a pollution (particularly atmospheric inputs) and recent vertical aerial photograph (Section 6.1.3). public access and disturbance. Disturbance caused A baseline record of individual trees is required. by public access and grazing are often of particular This can be supplemented by photographs from concern in wood-pastures. recorded points of a sub-sample of trees (Section Forestry practices are typically monitored by 6.1.4). The record will be a mixture of precise quan- stock maps. Stock maps can also record large- tities (e.g. girth) and classes (e.g. crown condition). scale natural disturbances; small-scale impacts Dead wood is commonly an important compon- can be detected by routine enumerations. See ent. Most takes the form of decay columns and Chapter 7 for more details on other impacts. dead branches on living trees. A supplementary record of fallen dead wood and stumps is desirable, 5.2.2 Specific issues affecting the based on the transect method (Section 6.5.5). monitoring of the habitat Once a baseline is established there is rarely any justification for repeating monitoring assessments The critical features of parklands are generally: at less than 10 year intervals. A sub-sample of trees 1. the mortality rate of existing trees, particularly can be checked between main recordings. the largest and oldest; 2. the amount and growth of recruitment; Regeneration 3. the amount and condition of dead wood; and Regeneration is commonly a critical issue in park- 4. the condition of ground vegetation. lands. Unlike in woodland, however, regeneration is generally achieved by planting with protection The peculiar character of parklands emphasises from grazing, or by protecting naturally set the need for monitoring at the level of individual 116 5 HABITAT REQUIREMENTS AND ISSUES

Table 5.2. A summary of the quality attributes providing an indication of the condition of wood-pasture habitats, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Size and shape Area of individual wood and Aerial photographs (Section 6.1.3) configuration of boundaries Phase I mapping (6.1.5) Comparison with historical maps (not described) Soil Structure Soil cores (6.2.2) Nutrient status Chemical analysis (not covered) or run-off chemistry (not covered) Hydrology Watercourse configuration Mapping Flooding regime River flow data/visual inspection Water chemistry Chemical analysis (not covered) Water table fluctuations Dipwells (6.2.1) Composition Stand pattern in managed forests: Stock mapping (6.5.1): covers all aspects of stand * extent of old, mid- and young growth pattern monitoring * extent and configuration of felling patches and canopy gaps * rotation of managed stands * stock of particular size classes * thinning extent and degree Communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition, richness and Species lists diversity Temporary plots (6.5.3) Plotless sampling (6.5.4) Structure Age class diversity Enumeration by permanent plots (6.5.2), tem- Horizontal and vertical structural porary plots (6.5.3), plotless sampling (6.5.4), diversity mapping individual trees (Part III, Section 15.2.4) Retentions to natural death Thinning extent and degree Deadwood: standing and fallen Enumeration (see above); measurement of fallen * volume wood and decay condition (6.5.5) * size distribution * spatial pattern Dynamics Open spaces Stock maps (6.5.1) Extent and location Fixed-point photography (6.1.4) Aerial photography (6.1.3) Seedling regeneration; composition, Enumeration (see above) number and distribution Ground vegetation condition (6.4) Renewal of coppice stools Amount and distribution of planting Provenance of planted stock and natural regeneration 5.3 Farmland boundary features 117

trees. It also offers excellent opportunities for retro- overhanging vegetation and high banks. This will spective monitoring, by using old maps, ground inhibit aquatic vegetation but may provide good photographs and aerial photographs. cover for animals. In contrast, wide drains with sunlit water will favour the growth of vegetation. Overall, therefore, it is generally advantageous 5.3 FARMLAND BOUNDARY FEATURES to aim for a variety of structures along stretches 5.3.1 Survey and monitoring requirements of ditch. This can be achieved by rotational and methods management. In general, the condition of ditches is dependent Attributes for assessing habitat condition on vegetation structure and composition, which is Farmland and field boundaries commonly consist in turn dependent on water quality and quantity of fences, ditches, grassy banks, walls or hedges, or (including seasonality), ditch structure and man- various combinations of these. Fences by them- agement. These attributes and influencing factors selves hold little of interest for biodiversity. should therefore be monitored. Vegetation can be However, the other features may be of considerable simply monitored by transects, with overall condi- conservation importance and may be the prime tion simply related to the number of submerged, source of biodiversity within artificial farmland floating and emergent wet bank species per 20 m landscapes. (see NCC, 1989). For further information on moni- Ditches may hold important aquatic, floating toring ditch vegetation see Alcock & Palmer (1985). and emergent plants, invertebrates and amphi- Other attributes will normally be dependent on bians, particularly where they occur alongside specific site conditions. semi-natural farmland habitats and are unpolluted Grassland banks and strips adjoining fields are by fertilisers, manure or pesticides. They may also important sources of biodiversity in the farm- also provide important feeding and breeding habi- land landscape. Under favourable conditions they tats for birds. Attributes used in assessing the con- may have relatively rich plant assemblages and dition of such habitats are water quality (in hold scarce or rare farmland species. They may particular, avoidance of eutrophication), water also provide suitable habitats for invertebrates quantity, ditch structure, vegetation structure and (especially overwintering insects), small mammals composition (i.e. avoidance of overgrazing or exces- and nesting birds. However, their quality is highly sive cutting and dredging). Water quality attributes dependent on their plant species composition and are covered in detail in Sections 5.9 and 5.10. the soil nutrient status. Sown grasslands, which are Where possible, water should be maintained in dominated by species-poor seed mixes and/or are the ditch all year. If ditches regularly dry out, they subject to fertiliser applications, are generally of have little value for aquatic plants and animals, low conservation interest. Further details on the although the ditch bed may contain some wetland attributes of grassland habitats and their monitor- plants. Deep ditches can hold permanent pools of ing methods are provided in Section 5.4. water without interfering with field drainage. As a At first sight walls may appear to be devoid minimum, ditches or pools should hold 30 cm of biological interest. However, old walls may har- of water (ideally 1 m) in stretches at least 3 m long bour rich lichen assemblages and potentially some (Andrews & Rebane, 1994). The structure of the rare or scarce species. They may also provide suit- ditch is also important for other reasons. In parti- able habitats for some plants (especially mosses, cular, shallow margins provide favourable condi- liverworts and ferns), invertebrates, amphibians, tions for wetland plants, invertebrates and reptiles, small mammals and birds. In general their amphibians. Poached margins provide particularly quality is primarily dependent upon their age (espe- good conditions for many invertebrates (P. Kirby, cially in the case of lichens, as these are extremely 1992), as well as feeding areas for birds. In narrow, slow-growing) and the presence of micro-habitats deep ditches, the bottom is often shaded by (such as crevices). Particular species inhabiting 118 5 HABITAT REQUIREMENTS AND ISSUES

walls may also be dependent on specific condi- species richness may be affected by structure tions, such as a damp or shady environment with (Pollard et al., 1974; P. Kirby,1992; Green et al., a particular aspect. 1994, Parish et al., 1994, 1995; MacDonald & Hedgerows are well known for their conserva- Johnson, 1995; Lewis et al., 1999). Structure is pro- tion importance in a wide range of farmland habi- foundly affected by management, and probably tats. Although they seldom hold rare species or also by age. The complexity of a laid hedge provides plant communities, they may hold relatively high better habitats for invertebrates and birds than diversities of plants and provide important sources does a simple line of bushes managed by cutting of food and cover for a wide variety of animals, or coppicing. Hedge-laying also maintains more especially insects and birds. Over 600 species of dead wood, which is particularly important for plant (including some endemic species such as invertebrates. the Whitebeam Sorbus devoniensis), 1500 insect spe- The external form of the hedge is an important cies, 65 bird species and 20 species of mammal attribute of hedgerow quality: trimming reduces have been recorded at some time living or breeding structural diversity and flowering and fruit produc- in hedgerows (Anon., 1995). They may also provide tion. Severe trimming will also reduce a hedge’s an important function in linking habitats in open suitability for nesting birds (Lack, 1987). A hedge farmland landscapes, thereby providing dispersal that is trimmed into an ‘A’ shape with a wide base routes for species that cannot cross large open may also shade out ground vegetation and become spaces (see, for example, Simberloff & Cox, 1987; less suitable for associated animals. In contrast, Bennett, 1990). a hedge that has become leggy, perhaps as a result Attributes providing an indication of the over- of browsing on lower growth by livestock, is poor all quality of a hedgerow are species composi- for scrub-nesting birds but is more likely to have a tion, structure, whether it contains trees, and well-developed and richer herbaceous ground its relationship to other habitats (Andrews & flora. However, the actual shape of a trimmed Rebane,1994). Older hedges in England tend to hedge may be less important for wildlife than is have a greater plant species richness and associated often claimed (Hill et al., 1995). The development of structural diversity (Pollard et al., 1974), as well as ground flora and associated animal communities is more mature trees and dead wood. These attri- much more likely to be influenced by accidental butes, in turn, support rich communities of inver- fertiliser applications and pesticide drift. tebrates and other animals. In contrast, recently Numerous methods have been used to describe planted hedges tend to have low plant species hedges, but they may not be the most applicable for diversity, often being dominated by Hawthorn monitoring. A summary of attributes giving an indi- Crataegus monogyna or Blackthorn Prunus spinosa. cation of habitat condition in hedgerows and recom- Proximity to woodland has also been shown to be mended methods for monitoring them is provided important for species diversity (Wilmott, 1980). below. This takes into account recommendations Another important aspect of species composition for a standard method for local Biodiversity Action is the presence of native species. Low numbers of Plan (BAP) surveys of hedges, which has been pro- non-native plants will not be a problem (unless posed by the UK Steering Group for the Species-rich they are particularly invasive), but hedges that are Hedgerow Biodiversity Action Plan. dominated by native species will hold more insects For monitoring hedgerow extent it is necessary (Kennedy & Southwood, 1984). Old hedges are also to adopt a consistent definition that can be readily more likely to be linked to non-farmed habitats and applied during field surveys. In this respect the may be extremely valuable if they are, for example, proposed UK Steering Group definition of a hedge- connected to ancient woodlands or other habitats row is ‘any boundary line of trees or shrubs less of high conservation importance. than 5 metres wide, provided that at one time the In general, tall, dense and broad hedges are rich- trees or shrubs were more or less continuous’. This est in biodiversity. Plant, invertebrate and bird broad definition is proposed because it avoids the 5.3 Farmland boundary features 119

need to distinguish between lines of trees and rows Hedgerows Regulations was found, but it was not of bushes. Earth or stone banks or walls are not predictive for middle-ranking hedgerows, and the included, in accordance with the Species-rich HEGS method cannot be used as a proxy for the Hedgerow BAP. However, if these features occur Hedgerows Regulations or vice versa. General sur- in association with a line of trees or shrubs, they veys can be carried out with these two methods are considered to form part of the hedgerow. together to maximise both ecological and context- A length of hedge between connections with ual information collected during surveys. other hedges or other linear features (i.e. inter- nodal length) is counted as a separate hedge. Management requirements and external impacts A hedgerow with a gap of more than 20 m is con- Farmland boundary features are profoundly affected sidered to be two separate hedges. by agricultural management practices (see Barr et al. Although the survey methodology proposed by (1995)forhedges)andthereforethese,aswellas the Steering Group is meant to be for species-rich habitat quality, should be thoroughly monitored. hedges, it could be applied to others. However, Stocking density and grazing or browsing inten- monitoring all hedges could be onerous and is sity can have serious impacts on the vegetation of unlikely to be a priority of a monitoring programme. ditch margins, grassy banks and hedges. Stocking It may be appropriate in many cases to target species- density can be easily monitored by regular stock rich hedges for monitoring beyond the simple head counts or by inspection of farm management assessment of extent. Species-rich hedges are records obtained directly from the landowner. defined in the Species-rich Hedgerow BAP as ‘any However, stock will preferentially graze some hedge that has 5 or more native woody species on vegetation. Monitoring grazing intensity, e.g. by average in a 30 metre length, or 4 or more in north- marking hedgerow branches and recording ern England, upland Wales and Scotland’. The BAP damage or by excluding grazing from banks and also recommends that hedges that contain fewer ditch margins, may therefore be a more reliable woody species but have a rich basal flora should be indicator of impacts, but it is more difficult. included if possible, although no practical criteria The accidental or intentional application of fer- have as yet been agreed for defining them on this tilisers, pesticides and other agrochemicals (e.g. basis. Table 5.3 summarises the attributes indicat- plant growth regulators) to farmland boundary fea- ing the condition of hedgerows, along with their tures can have major direct and indirect effects on recommended monitoring techniques. vegetation and animal communities. Farm records Rich et al.(2000) compared four different hedge can again provide basic data on their use, but these survey techniques on the same hedgerows: stand- will be of little value in predicting impacts unless ard 30 m lengths, 10 m plots, the Hedgerow such agrochemicals are not used or are applied Evaluation and Grading System (HEGS), and infrequently. Such data may also be unreliable. features of importance as defined in the UK Where fertilisers, pesticides, etc. are applied fre- Government’s Hedgerows Regulations 1997. All quently, impacts can only be assessed by more sophis- methods identified variation between hedgerows ticated procedures. Detecting fertiliser application which could differentiate between hedgerow may require chemical analysis of soils (Section 6.2.2) types (e.g. parish/community boundaries, new or water ( Section5.9.) Herbi cide and other pesticide hedgerows), or compare hedgerows in different applications may be detected by chemical analysis of areas (e.g. communities). The number of species soil and/or plants or indirectly from quadrats in 10 m lengths, 30 m lengths and the whole hedge- (Sections 6.4.2–6.4.5) if there are marked changes in row were highly correlated; surveys of sections can botanical composition (e.g. a marked decrease in the thus indicate overall species richness, although 30 m broadleaved herb component). Liming can be lengths gave better results than 10 m lengths. In detected from soil pH analysis (Section 6.2.2.)These general a good relationship between the HEGS monitoring methods are, however, likely to be time- value and the ‘importance’ as defined by the consuming, complex and difficult to interpret, and 120 5 HABITAT REQUIREMENTS AND ISSUES

Table 5.3. A summary of the quality attributes providing an indication of the condition of hedgerows, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I survey (Section 6.1.5) or aerial properties photography (6.1.3) Composition Presence/frequency of indicator species Species listings over defined hedgerow lengths, line transects (6.4.6), or quadrats (6.4.2–6.4.4) for hedge bottoms Species richness (woody species and Line transects (6.4.6) or quadrats (6.4.2–6.4.4) ground flora) for hedge bottoms Structure General structure and shape, including: Subjective visual assessment for major * length of gaps at top of hedge changes (e.g. trimming) or fixed-point * length of gaps in woody plants photography (6.1.4) * coverage at base of hedge * shape of hedge (e.g. ‘A’, box, etc.) Average height Sample measurements with a graduated pole, or fixed-point photography (Section 6.1.4) Width: Sample measurements with a graduated pole * average hedge width * width of rough herbage composed of native species at hedge base Density Subjective assessment or chequered board (see, for example, Fuller et al. (1989)) Dead wood Transect and subjective assessment of part (6.5.5) Presence of trees (live and dead) Include as target notes in Phase I surveys (6.1.5)

are therefore probably beyond the resources of most monitoring programmes. 5.3.2 Specific issues affecting the survey As described above, the structure of hedgerows and monitoring of habitat is primarily controlled by their management. As there is the possibility of agricultural practices Laying or coppicing is carried out to reinvigorate having a major impact on farmland boundary fea- the hedge and is best done on 8–12 year rotations. tures, monitoring should be carried out frequently. Trimming is routinely done to avoid excessive In particular, it is prudent to carry out routine site shading of crops, to maintain access and to retain visits annually to make simple visual inspections of the general shape of a hedge. To be most beneficial features and to monitor management practices. More for biodiversity, trimming is best carried out on detailed quantitative assessments of features should rotations of 2–3 years or longer (Andrews & be carried out at no more than 3 year intervals, or Rebane, 1994; Hill et al.,1995). These management immediately if annual inspections reveal apparent practices can normally be easily monitored from impacts or detrimental management activities. farm records or simple visual inspections every Some monitoring data can often be obtained couple of years (as the effects of trimming are visi- directly from landowners’ or managers’ farm records. ble for several years). However, as explained above, such general data may 5.4 Grassland and herbaceous communities 121

Table 5.4. Native woody species that occur in hedgerows in the UK These are typical species, not an exhaustive list.

Trees Shrubs

Common name Scientific name Common name Scientific name

Alder Alnus glutinosa Blackthorn Prunus spinosa Crab Apple Malus sylvestris Broom Cytisus scoparius Ash Fraxinus excelsior Elder Sambucus nigra Aspen Populus tremula Gorse Ulex europaeus Downy Birch Betula pubescens Gooseberry Ribes uva-crispa Silver Birch Betula pendula Guelder Rose Viburnum opulus Bird Cherry Prunus padus Hawthorn Crataegus monogyna Wych Elm Ulmus glabra Hazel Corylus avellana Elm species Ulmus spp. Gean (Wild Cherry) Prunus avium Juniper Juniperus communis Wild Plum Prunus domestica Dog Rose Rosa canina Holly Ilex aquifolium Pedunculate Oak Quercus robur Wild Rose Rosa spp. Sessile Oak Quercus petraea Spindle Euonymus europaeus Scots Pine Pinus sylvestris Bay Willow Salix pentandra Rowan (Mountain Ash) Sorbus aucuparia Eared Willow Salix aurita Crack Willow Salix fragilis Grey Willow Salix cinerea Goat Willow Salix caprea Osier Salix viminalis White Willow Salix alba Purple Willow Salix purpurea Whitebeam Sorbus aria

Sources: NCC (1988) and Stace (1997) not be an accurate indicator of the actual impacts of grasses and sedges is usually critical for monitoring management practices. Furthermore, such data may hedgerow ground floras, ditches and banks, and it not be reliable, for example as a result of inconsistent may be necessary to use a specialist botanist for record-keeping. It is also possible that some activities such detailed work. (intentional or accidental) may be concealed if they contravene management agreements or general codes of good environmental practice. 5.4 GRASSLAND AND HERBACEOUS Most general field monitoring of vegetation can COMMUNITIES be carried out between May and September, but 5.4.1 Survey and monitoring requirements should be carried out within the same 2 week per- and methods iod of the year as the original survey when repeating monitoring of ditches, grassy banks or Attributes for assessing habitat condition hedgerow ground flora. Grassland and herbaceous NVC communities are Hedgerow shrubs and trees are normally fairly designated features or attributes of broader habit- easily identified and can therefore be monitored ats of many SSSIs. A key requirement is therefore to by most biologists with general field training (see monitor their continued presence, extent and qual- Table 5.4). However, vegetative identification of ity. This can be carried out by repeat NVC surveys 122 5 HABITAT REQUIREMENTS AND ISSUES

incorporating properly replicated quadrat sam- exotic or invasive species, or indicators of poor pling (see Sections 6.1.6 and 6.4.2 for detailed dis- condition may also need to be monitored. For cussions) or by using appropriate mapping example, in species-rich Nardus grasslands, an techniques. Simple repeat NVC mapping is not con- absence or sparse cover of Crested Dog’s-tail sidered to be appropriate for monitoring purposes. Cynosurus cristatus and Perennial Ryegrass Lolium Many lowland sites are in enclosed areas on perenne is considered to be necessary for acceptable farms, and defining their extent is relatively simple. condition (Davies & Yost, 1998). On larger upland sites the grasslands may form part If it is only necessary to establish the presence or of a much larger complex, including blanket bog minimum approximate population of a species and heathland, and sampling is therefore required that is likely to be reasonably common and detect- to determine changes in extent and distribution. As able, then simple look–see or count methods may grassland composition is often strongly related to be adequate (see Part III, Sections 15.2.1 and 15.2.2.) soils and topography in such sites, careful stratifica- However, if species are rare or difficult to detect, or tion may be required to ensure that sampling if accurate quantitative assessments (e.g. of cover) designs are effective and efficient, and cover the are needed, sampling procedures such as quadrat full range of vegetation types present. or transect techniques will probably be required In addition, various aspects of the vegetation, (Section 6.4.) such as species richness, presence of particular The dispersal of species within a grassland can typical or indicator species, sward height and be of use when determining quality. When many cover, soil nutrient status, etc., may be needed to rare species or typical indicators are dispersed assess whether the quality of the vegetation is throughout the grassland at medium to high fre- being maintained. Species richness is an easily quency rather than being in single isolated clumps understood and measured variable, which can indi- at low frequency, grasslands are often old and of cate grassland quality. In general, the more species- high quality with a long history of the same rich a grassland, the more valuable it is for nature management. conservation. The diversity should be of species Sward height, cover and litter are valuable indi- characteristic of that community, and not extra- cators that should be monitored as a matter of neous species (e.g. non-native species or trees course when collecting quadrat data or surveying invading from adjacent woodland); some grass- sites. When swards are ungrazed, height, cover and lands are inherently more species-rich than others. litter all increase, resulting in decreased reproduc- One way to clarify that richness is an intrinsic tion of many species and a decrease in the propor- function of the community concerned would be tion of small, short-lived species. The presence of to assess the ratio of species listed in the appropri- associated grassland features, such as anthills, ate NVC table in Rodwell (1991 et seq.) to other often adds diversity and they may also be worth species, or to assess the ratio of constants, differ- monitoring in their own right. entials and preferentials to associates and other Table 5.5 summarises the attributes that indi- species (Rodwell, 1991 et seq.). Bear in mind that cate the condition of grasslands and gives recom- oversampling a local community will result in a mended techniques for monitoring them. Detailed number of constants higher than that indicated in methods and reviews of monitoring grasslands are the NVC tables. outlined by Byrne (1991), Hodgson et al.(1995) and The presence and/or abundance of particular Robertson (1999). species may often be considered useful in helping to define condition in many grassland and other Management requirements and external impacts vegetation communities. These most often relate Monitoring of management practices (Sections to desirable species that are of conservation impor- 7.1–7.3) may be as important as monitoring the tance or species that are indicators of favourable quality of the habitat. It should perhaps be carried ecological condition. Undesirable species, such as out as part of a site monitoring programme. 5.4 Grassland and herbaceous communities 123

Table 5.5. A summary of the quality attributes providing an indication of the condition of grasslands, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent and distribution Phase I mapping (Section 6.1.5) with aerial properties photography (6.1.3) for basic long-term monitoring NVC surveys with quadrat sampling (6.1.6) for NVC vegetation types Soil nutrients Chemical analysis (not covered) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Functional components of FIBS (6.4.4) vegetation Species composition and richness Mini-quadrats (6.4.3) Presence/absence of typical/ Look–see or total counts (Part III, Sections 15.2.1 indicator species and 15.2.2, ) quadrats6.4.2 ( , 6.4.3 ) or transects6.4.6 )( Structure Sward height Drop-disc, ruler Cover Conventional quadrats (6.4.2) or point quadrats (6.4.5) if precise measurements are required Litter Quadrats (6.4.2)

Most grassland and herbaceous communities some vegetation types in preference to others, need to be managed by mowing, burning or graz- monitoring the stocking density alone for a site ing to maintain their quality. There are often may not reflect the true grazing pressure on valu- severe practical difficulties in ensuring that these able vegetation. Here, more detailed methods, such operations are carried out at the right time each as counting the proportion of grazed shoots or year, and therefore monitoring of such activities leaves, may be required. will often be needed to establish a long-term view Detecting fertiliser application may require chem- of the stability of the community. ical analysis of soils (Section 6.2.2). Herbicide appli- Grasslands vary in their sensitivity to changes in cation may be detected by chemical analysis of management and subsequent recovery. For plants and/or soil or indirectly from quadrats instance, application of fertiliser to nutrient-poor (Sections 6.4.2–6.4.4) where there are marked grassland may result in rapid and irreversible changes in sward composition (e.g. a marked changes, yet effects due to the absence of grazing decrease in the broadleaved herb component). can be reversed after even a decade. In setting the Liming can be detected from soil pH analysis timescale for monitoring, any threats to, and the (Section 6.2.2.) Some management monitoring sensitivity of, each site and community will there- data can often be obtained from the landowners’ fore need to be considered. or managers’ farm records. However, such data Monitoring stocking density may require regu- may not be reliable, for example as a result of in- lar stock head counts, although stock will often consistent record-keeping. It is also possible that graze some types of grassland in preference to some actions (intentional or accidental) may be con- others. When stock are absent, previous use can cealed if they contravene management agreements be assessed from dung. As stock selectively graze or general codes of good environmental practice. 124 5 HABITAT REQUIREMENTS AND ISSUES

On upland grasslands the impacts of grazing and scattered vegetation to pastures, woodland clear- burning can be monitored by using the method ings and closed woodland canopies. The resulting developed by MacDonald et al.(1998a,b) for SNH. diversity and unusual combinations of plants of woodland, rocky habitats and grassland growing together on a pavement are key attributes, resulting 5.4.2 Specific issues affecting the survey in a range of NVC types. Ward & Evans (1976) and monitoring of habitat regarded open pavements as the most important Grasslands and herbaceous communities should be floristically. Open pavements with a good ‘view’ monitored at 3 or 6 year intervals. Hay meadows are also important from an earth science perspec- should be surveyed before they are cut. Most gen- tive, but the maintenance of existing woody cover eral monitoring can be done between May and is often necessary to maintain overall diversity. September but should be carried out within the Ward & Evans (1975, 1976) documented all the same 2 week period of the year as the original limestone pavements in Scotland and England and survey when repeat monitoring. included species lists for all sites, with a crude Vegetative identification of grasses and sedges is estimate of frequency. They limited floristic record- usually critical for monitoring grasslands, so the ing to grikes more than twice as deep as they were work will need to be carried out by a specialist wide, and this method should be followed for botanist. consistency. Species lists were used to create a flor- When carrying out assessments of grasslands it istic index, which was used to rank pavements, should be remembered that it can be difficult to and deviations from this figure can be used to record quadrats safely and effectively if inquisitive monitor maintenance of diversity. Most surveys stock are present. Trampling by stock can also took about one hour by two botanists, and it is affect tall herb vegetation, and lodging (vegetation suggested that this should be repeated as closely falling over as a result of excessive growth, wind or as possible and at a similar time of year. Repeat rain) has marked effects on the ease and accuracy botanical surveys will vary depending on the bot- of recording quadrats. anist and the amount of effort, so measures should be taken to standardise surveys (Rich & Smith, 1996). As site-based surveys return generally simi- 5.5 LIMESTONE PAVEMENT lar but rarely identical species lists, the floristic 5.5.1 Survey and monitoring requirements index from repeat surveys should be within Æ20% and methods of the Ward & Evans (1975) baseline figure to account for sampling error and indicate mainte- Attributes for assessing habitat condition nance of the floristic index. In Europe, limestone pavements are restricted The earth science interest centres on mainte- to Britain and Ireland, and internationally they nance of the key physical features for which each are a rare habitat. Most pavements are quite small site is selected (such as the grikes), and their visibil- and extend over only a few hectares. All examples ity (i.e. they should not be covered by excessive are important irrespective of size, and extent vegetation). The variation in structure of grikes should be monitored to check for damage and and other typical karst geomorphological features, encroachment. From a national study only 3% of such as solution basins, erratics, runnels, etc., is pavements in Britain were found to be undamaged also important for the biological features of the and only 13% were 95% or more intact (Ward & pavements as it adds a diversity of habitats. Evans, 1976). Physical structure is unlikely to change except by The biological interest is provided by a variety damage, although perched erratics tend to get of microclimates, which results in a mosaic of pushed off by vandals. different plant communities. The development During the botanical survey, notes can be kept of of vegetation over pavements ranges from sparse, damage by geologists (these are typically small 5.5 Limestone pavement 125

Table 5.6. A summary of the quality attributes providing an indication of the condition of limestone pavements, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I or NVC survey (Sections 6.1.5 and 6.1.6), properties aerial or fixed-point photography (6.1.3 and 6.1.4) Removal of limestone, damage by Field surveys geologists Composition Floristic index See text and Ward & Evans (1975, 1976) Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Structure Cover of wood and scrub Aerial or fixed-point photography (6.1.3 and 6.1.4) chips taken off edges of grikes, often obvious On pavements with deep grikes, low-intensity graz- because of their lack of lichen or algae cover). ing may be tolerated. Some improvements may be Existing damage can be marked with a small spot achieved locally if grazing is reduced or removed. of enamel paint so that new damage can be Air pollution and acid deposition could well be assessed, but this is usually a relatively minor prob- damaging the geomorphological features as a lem. Table 5.6 gives a summary of attributes useful result of an increased rate of erosion, although when assessing the condition of limestone pave- this is a slow process and a long-term problem. ments and the methods recommended for moni- Lichens may have some role in protecting the pave- toring them. ments from weathering. The amount of public pressure, and hence the amount of monitoring of damage required, will Management requirements and external impacts vary depending on catchment area. For example, Variation in woody cover of pavements is import- some sites in Scotland do not appear to be under ant for the diversity of the habitat in its own right; the same public pressure as those in England, and in cases in which biological sites have been there seems to be little point in monitoring erosion selected to include this, maintenance of the exist- or other damage from visitors unless it is identified ing woody cover is regarded as desirable. If sites as a potential problem. have been selected for their earth science importance, the requirement for open views should be 5.5.2 Specific issues affecting the survey taken into account. and monitoring of habitat In the past limestone pavements have been widely damaged by removal of limestone for rock- It is recommended that these sites are monitored at eries, walls and building materials, and minor 3–6 year intervals. This should be carried out damage still occurs from geological sampling. between June and September when the flora is Because of the difficulty of stock grazing on fully developed. limestone pavements, most sites are unlikely to be The boundary of the limestone pavement should under threat from an increase in cattle grazing be taken as the edge of the exposed limestone. The pressure but there may be a gradual impoverish- small size and relative accessibility of most pavement associated with sheep grazing. Some open ments, and the existence of a standard method pavements that support rarities should continue to (Ward & Evans,1975), will not impose significant be lightly grazed to prevent scrub encroachment. logistical limitations on surveys. 126 5 HABITAT REQUIREMENTS AND ISSUES

Fixed-point photography has worked well as a having a cover of 25% or more of the main erica- monitoring tool at a number of sites, and is useful for ceous species (Calluna, Empetrum, Vaccinium or Erica assessing changes in woody cover or limestone spp.) (NCC, 1990a,b), and cover of these species extraction. Aerial photographs are also useful for is therefore an essential indicator of condition. spotting limestone removal on larger pavements. Gorse (Ulex spp.) may also be important on lowland NVC surveys with quadrat sampling of each heaths. Much of the vegetation is naturally species- grike are unlikely to be worth while, and may be poor but no one plant species should cover more difficult because of the patchy nature of the vegeta- than 90% of the ground. This will allow the devel- tion. A broad overview of the vegetation types opment of diversity within the limits characteristic should be taken. Quadrats (Section 6.4.2) or trans- of the habitat. In the west, heathland may be very ects (Section 6.4.6) may be useful for assessing important for oceanic bryophytes and lichens. changes in vegetation related to grazing. Heavy grazing and excessive burning (or poor burn- Particular care should be taken when undertaking practices) may result in reduced cover of erica- ing fieldwork because of the risks of falling on ceous and other species. slippery pavements in wet weather. Monitoring In general, mixed-age stands of ericaceous spe- should be carried out by two people, and other cies on heathlands are more valuable than homo- appropriate safety measures outlined in Box 2.11 geneous stands, as the former tend to have more should be followed. microhabitats for invertebrates, lichens, bryophytes and higher plants, and they also indicate 5.6 LOWLAND AND UPLAND HEATHLAND that regeneration conditions are suitable. Bare ground may vary from large areas in recently 5.6.1 Survey and monitoring burnt stands to virtually none in closed mature requirements and methods stands; this is quite natural, but some bare ground is usually desirable. Attributes for assessing habitat condition Scrub (birch, pine) and Bracken Pteridium inva- Heathlands are subject to significant reclamation sion is often a problem on both lowland and upland pressure, at least in the lowlands. Most heathland heaths and may not be desirable, although it is an types occur as part of habitat mosaics in which they integral part of the habitat. exhibit gradations into other communities (e.g. A summary of attributes useful when assessing grassland, blanket bogs). They show strong edge the condition of heathlands is provided in Table 5.7 effects and are vulnerable to fragmentation. It is together with recommended monitoring methods. therefore important to monitor their extent and An additional method for monitoring Heather distribution. Calluna vulgaris cover is given in MacDonald & Soils are a key feature determining the nature of Armstrong (1989). the heathland vegetation. They tend to be acidic, nutrient-poor podzols and shallow peat. Soil pH Management requirements and external impacts may not always be low; in The Netherlands the Heathlands are semi-natural habitats, and require rarer heathland plant species are often associated management techniques such as grazing, burning with soils of pH greater than 5 (Roem & Berendse, or cutting (with the possible exception of some 2000). Nutrient enrichment is usually very dam- maritime heaths) to maintain structural and spe- aging. Heathlands may be freely drained or more cies diversity and prevent scrub encroachment. or less permanently waterlogged. Wet heath types Low-intensity grazing is often valuable in creat- may depend on a high water table, which may ing diverse microhabitats and is the preferred man- require monitoring. agement, although it is not always practicable In general the more diverse the heathland in (Gimingham,1992). Grazing regimes need to be terms of characteristic heathland species and struc- adapted to local situations. Many upland heaths ture the better. Heathlands are usually defined as are managed as grouse moors by patchwork 5.6 Lowland and upland heathland 127

Table 5.7. A summary of the attributes providing an indication of the condition of heathlands, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent and distribution Phase I mapping (Section 6.1.5) with aerial properties photography (6.1.3) for basic long-term monitoring NVC surveys with quadrat sampling (6.1.6) for NVC vegetation types Soil pH and nutrients Soil analysis (6.2.2) Bare ground Conventional quadrats (6.4.2) Water table Dipwells or WALRAGS (6.2.1) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Ericaceous and other keystone Conventional quadrats (6.4.2), aerial species cover photographs (6.1.3) Species composition and richness Conventional quadrats (6.4.2) or line/point intercept transects (6.4.6) Presence/abundance of Look–see or total counts (Part III, Sections 15.2.1 and typical/indicator species 15.2.2)quadrats(6.4.2 and 6.4.3) or transects (6.4.6). Structure Occurrence and scale of Transects (6.4.6) and fixed-point horizontal and vertical photography (6.1.4) structure (patchiness) Drop-disc or ruler for height Age/physical structure of Plant size and demographic techniques (Part III, ericaceous shrubs Sections 15.2.3 and 15.2.4) Scrub invasion Fixed-point (6.1.4) or aerial photography (6.1.3) burning, or as sheep walks. Overgrazing can occur, normally near supplementary feeding locations or 5.6.2 Specific issues affecting the survey around the lower margins of moors close to better- and monitoring of habitat quality pastures. Grazing and burning are key fac- It is recommended that heathlands are monitored tors on many heaths, and much impact monitoring at 6 year intervals. Late summer is an appropriate will be directed towards this (Sections 7.1–7.2)A time for monitoring floristic parameters, as the method for monitoring the impacts of upland weather is likely to be better and the plants fully land management practices has been developed developed, but work can be carried out for most of by MacDonald et al. (1998a,b) for SNH. the growing season (April–October) in these essen- Air pollution should be below the critical con- tially evergreen communities. Early spring is the centrations required to maintain the low nutrient best time to monitor heather browsing, after win- À3 À3 status of the heaths (SO2 10 mgm ,NO2 30 mgm , ter browsing has finished but before new growth À3 NH3 8 mgm ) (English Nature, 1993). In recent occurs. Access may be difficult late in the season years concentrations of SO2 have declined as a because of deer stalking or grouse shooting. result of effective drives to remove such emissions Sites containing heathlands are often very large from power stations across Europe, whereas pollu- and complex, with other related vegetation types tion from NOx remains a problem. 128 5 HABITAT REQUIREMENTS AND ISSUES

such as blanket bogs intermixed. Monitoring may examples are small and widely scattered, often therefore have to be integrated with that of other occurring as isolated, fragmented sites in the low- habitats. The large scale can make access difficult if lands, and this fragmentation imposes significant vehicle tracks are absent, and walking though tall limitations on their potential for recovery after heather can be extremely tiring. damage. Fens are among the habitats that have The large size of many heathland sites also undergone the most serious declines across means that sampling will be essential, as it will Europe. Swamps and reedbeds often occur around not be possible to monitor the whole site. As heath- the margins of lakes, lochs, pools and rivers land composition is often strongly related to soils (Sections 5.9 and 5.10). and topography in such sites, careful stratification These habitats are wetlands, and the rise and fall may be required to ensure that all communities of the water table and movement of water are and subcommunities are adequately and efficiently important factors in determining the plants and sampled. Stratification according to ownership or communities that occur. The height of the water management may also be appropriate because this is table, typically at or slightly above or below that of likely to be the major factor determining the condi- the substrate, appears to be especially important in tion of the vegetation. In large areas of uniform moor- controlling zonation and succession to other vege- land it may also be efficient to carry out sampling tation types. Hydrological regimes should there- using a multi-level strategy (Part I,Section2.3.3.) fore be monitored, but this is a complex subject Accurately determining location can be difficult that cannot be covered here (see Section 6.2.1.) when mapping. Boundaries between communities Similarly, water chemistry has a profound influ- can be ecotonal in nature, and different surveyors ence on wetland vegetation and should be carefully may not be consistent in their interpretation of monitored. Further information on this subject is boundary locations. provided in Section 5.9. Heather damage may be caused by inverte- Fen vegetation is variable but very distinctive brates, especially certain moth species (e.g. Winter and contains many species that are rare or scarce. Moth Operophtera brumata caterpillars) and the The type of vegetation and its richness are key Heather Beetle Lochmaea suturalis. Damage can also indicators of habitat quality. Wheeler (1989) probe due to other factors, such as weather and fungal posed that two botanical indices based on richness diseases. indicators and rare species could be used for rapid evaluation of sites; a similar approach could also be used for monitoring. 5.7 FENS, CARR, MARSH, SWAMP There is often some variation in topography AND REEDBED across a fen, which can be important for maintain- 5.7.1 Survey and monitoring requirements ing diversity. The vegetation itself often forms and methods small mounds with wetter areas between (and sometimes shallow pools), allowing species of wet Attributes for assessing habitat condition and dry ground to grow adjacent to each other. This group includes a range of habitats, each of Variations in topography may also be associated which presents its own problems for monitoring. with old peat cuttings. Natural transitions to non- Carr is essentially swampy woodland; monitoring fen habitats are rare features and can be of high techniques appropriate for woodlands will there- value. fore be important (Section 5.1.) Marsh monitoring A summary of attributes that are useful in pro- will include techniques appropriate for grasslands viding an indication of the condition of wetlands and herbaceous vegetation (Section 5.4). is provided in Table 5.8 together with recom- Fens may vary from small areas around a calcar- mended monitoring methods. Rowell (1988) pro- eous spring to large sites (e.g. the 300 ha Insh vides practical advice on monitoring peatlands Marshes near Kingussie); size is critical. Most including fens. 5.7 Fens, carr, marsh, swamp and reedbed 129

Table 5.8. A summary of the quality attributes providing an indication of the condition of wetlands, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I mapping (Section 6.1.5) with aerial properties photography (6.1.3) for basic long-term monitoring NVC surveys with quadrat sampling (6.1.6) for NVC vegetation types Soil pH and nutrients Soil analysis (6.2.2) Hydrological regime Piezometer, dipwells or WALRAGS (6.2.1) Water chemistry Macrophyte indicators for standing waters or chemical analysis (not covered) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition and richness Conventional quadrats (6.4.2) or line/point intercept transects (6.4.6) Presence/abundance of Look–see or total counts (Part III, Sections 15.2.1 and typical/indicator species 15.2.2)quadrats(6.4.2 and 6.4.3) or transects (6.4.6). Structure Vegetation height Drop-disc or ruler Scrub invasion Fixed-point (6.1.4) or aerial photography (6.1.3)

species composition. High species richness is Management requirements and external impacts strongly related to low nutrient status. Nutrient The main threats to fens are reclamation, drainage enrichment by agricultural fertiliser run-off or sew- and abstraction from aquifers, cessation of tradi- age is therefore highly damaging. Rivers tend to tional management practices such as grazing and have high nutrients in their sediments, although turf cutting, overgrazing, eutrophication, develop- fens can occur in floodplain situations. ment of scrub, and flood defences. Some of these may require off-site monitoring, and large-scale catchment protection may be required for fens 5.7.2 Specific issues affecting the survey because of their dependence on the flow of ground and monitoring of the habitat or surface water of an appropriate quality. Management of fen vegetation varies. Some These habitats should be monitored every 3 years. short fens are maintained by light grazing and its The vegetation of wetlands is most developed late associated trampling, the low nutrient concentra- in the summer (July–September) and is best moni- tions and scouring by water erosion. Reedbeds tored in August when water levels are at their low- should not be grazed. These and others, such as est. The presence of breeding birds may also Cladium (sedge) beds, may require regular cutting. restrict access at other times of year. Peat cutting and scrub clearance are also required A high level of botanical skill is needed for NVC in some sites. surveys of fens and similar habitats because of the Minerotrophic or topogenous fens develop under range of difficult groups, such as grasses, sedges the influence of ground water, the nutrient content and bryophytes, which form important parts of of which is critically important in determining the vegetation. 130 5 HABITAT REQUIREMENTS AND ISSUES

It may be very difficult to place quadrats in tall Topography is a second attribute. Lowland swamp without damaging the vegetation; transects raised bogs form deep peat deposits of variable may be easier to record. If largish areas of uniform depth (5–10 m) with a flat or gently sloping topo- vegetation are picked to minimise edge effects, graphy and sometimes a steeper edge. Most natural quadrats can be crudely delimited by placing ran- undisturbed bog surfaces usually show distinctive ging poles sideways through the vegetation. Rowell fine-scale variation with small drier hummocks (1988) suggests the use of circular quadrats, which and wetter hollows related to growth of Sphagnum can be threaded through the vegetation. In either and other plants. case it can be difficult to see both sides of the A third attribute is the water table. The water table quadrats clearly without trampling vegetation all may be maintained by both rainwater and ground around. water (Lamers et al., 1999). It is higher than the sur- Fens are difficult habitats to survey. Tall swamp rounding land and is therefore very susceptible to vegetation is disorienting and difficult to walk drainage. Invasion by birch or willow may indicate through; there may be sudden changes to open surface flushing or that the bog is drying out. water and the surface may be unstable because of Transects of dipwells may therefore be valuable to floating vegetation. Aerial photographs may be provide hydrological information but, as there are invaluable for mapping inaccessible areas at a gross long-term natural cycles of drying and wetting scale. Some access by boat can help with surveying. related to natural variations in climate, dipwell data Chest waders are more useful than wellington boots. may need to be correlated with rainfall. Eye protection may be needed in reedbeds. A fourth attribute is the presence of (and Permanent markers may be difficult to relocate preferably active formation of) the peat itself. under water, in deep peat or in tall vegetation, but Assessments of whether peat growth is active or are unlikely to be interfered with because of their not can be made by measuring peat depth and rates location. Birds may perch on them, resulting in of peat accumulation directly, although if decom- localised nutrient enrichment from droppings. position in the catotelm equals accumulation in Vegetation can be quite heterogeneous, and is the acrotelm, the net result is no peat accumula- amenable to investigation through transects and tion, despite the fact that peat is actively being laid by stratified sampling. down. Strictly speaking, active growth of peat is therefore a feature of peat formation, not of peat accumulation. Peat shrinkage is usually caused by 5.8 LOWLAND RAISED BOG drainage or other disturbance. The characteristic 5.8.1 Surveying and monitoring vegetation is dominated by Sphagnum spp. (espe- requirements and methods cially S. papillosum, and sometimes S. magellanicum), and it is important that a healthy growth is main- Attributes for assessing habitat condition tained in wet conditions. To a large extent, if the Raised bogs have been officially recognised as one Sphagnum is healthy and growing, the remainder of of Europe’s rarest and most threatened habitats. the habitat should be in good condition. Since 1840 the area of primary, active lowland A summary of attributes that provide an indica- raised bog in the UK has decreased from around tion of the condition of lowland raised bogs is pro- 95 000 ha to 6000 ha, a decline of 95%. Only about vided in Table 5.9 together with recommended 3800 ha of this remains intact, some 800 ha of monitoring methods. Stoneman & Brooks (1997) which are in Scotland. Extent is thus the first and Rowell (1988) provide practical advice on moni- important attribute to monitor. The most common toring bogs. causes of loss have been peat extraction or conversion to agriculture or forestry. Mineral extraction, Management requirements and external impacts built developments and neglect probably account The management of bogs can markedly affect the for most of the recent losses. quality of the site. Grazing, burning, drainage, 5.8 Lowland raised bog 131

Table 5.9. A summary of the quality attributes providing an indication of the condition of lowland raised bog, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I mapping (Section 6.1.5) with aerial photography properties (6.1.3) for basic long-term monitoring NVC surveys with quadrat sampling (6.1.6) for NVC vegetation types Water table Dipwells or WALRAGS (6.2.1) Peat depth Soil cores (6.2.2) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition and richness Quadrats (6.4.2–6.4.4) or transects (6.4.6) Presence/abundance of typical/ Look–see or total counts (Part III, Sections 15.2.1 and indicator species 15.2.2) quadrats (6.4.2 and 6.4.3) or transects (6.4.6) Sphagnum cover Conventional quadrats (6.4.2) or transects (6.4.6) Structure Pattern (hummock/hollow, bog Quadrats (6.4.2–6.4.4), transects (6.4.6), or fixed-point pools, etc.) (6.1.4) or aerial (6.1.3) photography for large-scale surveys Scrub invasion Fixed-point (6.1.4) or aerial photography (6.1.3) Dynamics Peat formation Growth of Sphagnum forestry and scrub invasion can all damage the Maps are usually too small in scale to show the vegetation. Under natural conditions raised bogs detailed minor topographical variations, and find- may have been lightly grazed or ungrazed (unli- ing your location on a bog may be a significant kely), and most will survive by themselves if the problem. Furthermore, as there are fine gradations water table and air pollution regimes are between many bog communities, there is likely to satisfactory. be significant variation in the boundaries drawn by different surveyors; monitoring such boundaries is 5.8.2 Specific issues affecting the survey unlikely to be reliable. Aerial photographs may be and monitoring of habitat really helpful for both location and boundary delimitation. Careful stratification may be required to It is recommended that bogs are monitored at ensure that the range of bog communities and sub- intervals of not less than 3 years. They should communities is adequately covered and sampling ideally be surveyed in June–October when their is carried out efficiently. vegetation is fully developed, but as they support Vehicular access is always undesirable and in few annual or deciduous species it is possible to any case is usually impossible. Trampling can survey them in all seasons. affect Sphagnum cover on some bogs, with foot- Air pollution (especially sulphur-based pollution) prints remaining for 20–30 months. It is very easy is known to damage Sphagnum communities, so to damage bog vegetation during a survey, and favourable conditions in the long term will require damage by trampling around permanent quadrats pollution climates below the critical thresholds (SO2 is often excessive (Rowell,1988). Duckboards, lad- À3 À3 À3 10 mgm ,NO2 30 mgm ,NH3 8 mgm ) (English ders or inflatable mattresses can help to spread the Nature, 1993). Ground water quality can also affect weight of the surveyor. Permanent markers may be bog communities (Lamers et al., 1999). difficult to relocate or may become overgrown by 132 5 HABITAT REQUIREMENTS AND ISSUES

Sphagnum; the sensitivity of the vegetation to tram- Table 5.10. The trophic categories of waters pling means that non-permanent techniques in terms of nitrogen and phosphorus should be used wherever possible. These effects, coupled with small-scale variations from year to Total P Inorganic N year, can make comparisons problematic. Status (mgÀ1) (mgÀ1) Ideally, the peat moss should be intact, but most bogs have been damaged in one or more ways by Ultra-oligotrophic <0.005 <0.02 cutting, drainage, burning, grazing, agriculture, Oligo-mesotrophic 0.005–0.01 0.2–0.4 forestry and other developments. If these activities Meso-eutrophic 0.01–0.03 0.30–0.65 are still continuing, specific monitoring of their Eu-polytrophic 0.03–0.1 0.5–1.5 effects may be required (see Chapter 7). Polytrophic >0.10 >1.5 Bogs can be dangerous and should be surveyed with care. Safety guidelines outlined in Part I, Box Source: From Vollenweider (1968). 2.11 should be followed. are therefore fundamental to assessing condition and must therefore be monitored and maintained. 5.9 STANDING OPEN WATER Other important plant-related attributes include NVC 5.9.1 Surveying and monitoring community species richness, taking into account the requirements and methods level of richness expected for the type of water body. ArichassemblageofPotamogeton spp. in particular Attributes for assessing habitat condition is also a good indicator of high botanical quality. An This habitat class includes both natural and artifi- extensive fringe of emergent vegetation is also a cial standing fresh waters, ranging in size from a desirable attribute of an open water site, even if its few square metres upwards, and therefore encom- intrinsic value as fen habitat is not high. passes a large variety of habitats in Britain, includ- The abundance and availability of phosphorus ing freshwater lochs, meres, reservoirs, gravel pits, (Table 5.10) normally limits and therefore determines ponds, canals and temporary pools. As a result of the growth of phytoplankton and macrophytes this variety and the special character of these habi- (Mainstone et al., 1993). Under certain circum- tats, their attributes and the monitoring methods stances, nitrogen can be the limiting nutrient for can only be outlined in this Handbook. Further infor- aquatic plants, particularly if phosphorus concentra- mation is available on these topicsrecom- in thetions are very high as a result of enrichment from mended reference sourceslisted at the end of sewagethe treatment works or internal loading. book. Lagoons and other marine habitats are not However, the availability of plant nutrients covered by this volume. Ditches were discussed in changes with the seasons as a result of a variety of Section 5.3. influences. Therefore, a more constant measure of Palmer et al.(1992) found that their plant com- productivity is provided by alkalinity (Table 5.11). munity classification closely followed classifica- According to this scheme, water bodies are conventions based on water chemistry (see, for example, tionally classed as dystrophic, oligotrophic, meso- Vollenweider, 1968; Ratcliffe, 1977). Submerged trophic and eutrophic in increasing order of and floating macrophytes form the primary basis calcium carbonate concentration and productivity. for the classification and selection of SSSIs for A fifth class is marl lakes, which have the highest freshwater habitats (NCC, 1989). For standing levels of alkalinity but in which productivity is waters, representative sites are selected for each limited because phosphate is bound to the sedi- of ten types of macrophyte community identified ment and therefore unavailable for plant growth. from a detailed study of water bodies throughout Dystrophic waters include the small water- Britain (Palmer, 1989; Palmer et al., 1992). The char- bodies and pool systems commonly found on peat acteristic macrophyte communities of these types bogs. They are solely rain-fed and thus receive 5.9 Standing open water 133

inherent and inseparable characteristic of such Table 5.11. Alkalinity characteristics of different features (see Part II, Section 2.1.2 and Glossary). types of freshwater body Consequently, a common requirement of monitoring standing waters is to measure their character- Alkalinity istic nutrient and pH properties to ensure that

CaCO3 these are being maintained within natural fluctua- Status (mg lÀ1) mequiv. lÀ1 pH tions. Direct measurement of such chemical properties can be undertaken but interpretation may Dystrophic 0–2 0.00–0.04 <6 not always be straightforward. However, as macro- Oligotrophic 0–10 0.0–0.2 6–7 phytes are highly influenced by water chemistry, Mesotrophic 10–30 0.2–0.6 c.7 monitoring information on their distribution and Eutrophic >30 >0.6 >7 abundance can provide information on water Marl >100 >2.0 >7.4 chemistry conditions. Macrophytes have been widely used for pollution monitoring of rivers in Source: From Ratcliffe (1977). Europe and the UK, but less so for standing waters. Palmer et al. (1992) used the results of their analysis water that contains no mineral salts dissolved from of macrophytes (as described above) for the devel- the underlying rocks (Andrews, 1995). Peat staining opment of a ‘trophic ranking score’ system that also reduces light penetration and macrophyte allows assessment of changes in trophic status growth. Consequently, productivity is low and over time. See Palmer (1989) and Palmer et al. they support a restricted range of flora and fauna. (1992) for further details. The water is also often too acidic to support fish. Advantages of using macrophytes to monitor However, the absence of fish and low numbers of water chemistry include the fact that they are other predators such as birds provides favourable generally large and easy to identify with the conditions for dragonflies, water bugs, midges and naked eye, can be sampled rapidly, are present other invertebrates. throughout the summer months, and can act as Oligotrophic waters are typically upland lakes accurate reflectors of overall conditions at a fixed in areas with hard, nutrient-poor rock types. They point within a water body (Bell, 1996). The disad- have a low biodiversity and biomass of plants vantages of using macrophytes are their seasonal- and animals; fish are principally salmonids. ity, the lack of knowledge about their natural Mesotrophic waters have the highest biodiversity population fluctuations and difficulties with the of standing fresh waters, often combining ele- identification of some species. ments of oligotrophic and mesotrophic systems, A standard method for surveying aquatic macro- and also support rich and abundant macrophyte phytes was developed by the Nature Conservancy communities. Furthermore, relative to other types Council (NCC) and has been used since 1975 to of lake, they contain a high proportion of nation- record aquatic information on standing water ally rare and scarce species of aquatic plants bodies throughout Britain. This has been used as (Anon., 1995). Macro-invertebrates are also particu- the basis for the botanical classification of standing larly well represented. Eutrophic waters are more waters described above (Palmer, 1989; Palmer et al., typical of lowland areas of Britain and support a 1992). The method entails walking the perimeter of high biomass of vegetation (including plankton the water body to record shoreline and shallow- and macrophytes), and high numbers of fish water vegetation. Deeper water is sampled by (usually coarse species such as cyprinids, Perch means of a grapnel thrown from the bank at fre- Perca fluviatilis and Pike Esox lucius) and birds, par- quent intervals during the perimeter walk. Where ticularly in winter. possible, a boat is used, and grapnel samples are Nutrient status is therefore normally regarded obtained from the bottom during transects of the as a key attribute of water bodies, as it is an lake and passages parallel to the shore. The cover of 134 5 HABITAT REQUIREMENTS AND ISSUES

all aquatic plants is recorded on a subjective calibrated line until the disc is no longer visible, DAFOR scale of abundance: dominant, abundant, at which point the depth is recorded. The disc is frequent, occasional, rare. Although this technique then lowered further and raised until it reappears, is suitable for the classification and conservation at which point a second depth reading is taken. The evaluation of standing water bodies it is too sub- average of these depths is the final Secchi disc jective and insensitive to be adequate for all but the visibility reading. This reading provides a relative most basic monitoring purposes. The DAFOR scale measure of water clarity, but can also be used to in particular is highly subjective and prone to con- calculate the depth to which photosynthetic organ- siderable interpretative variation between obser- isms can occur. This is termed the euphotic zone vers (see Section 6.4.2.) (Zeu) and is between 1.2 and 2.7 times the Secchi A variety of methods have been used for moni- disc depth (Moss, 1998). Secchi disc measurements toring macrophytes, including satellite imagery should be made under consistent light conditions and aerial photography, grab and rake sampling, and in calm water. Even then, measurements tend subaqua diving and the use of sonar and remotely to differ according to conditions and variation operated vehicles (ROVs); see Bell (1996) for a between observers. For more accurate measure- review. However, none of these methods has been ments, underwater light meters should be used, developed to a stage of wide application and there or turbidity (the concentration of suspended parti- are no accepted standard protocols. Nevertheless, a culate matter) can be measured by using a turbidity suggested technique for the use of grapnel samples meter or a suspended solids monitor. to obtain semi-quantitative data on macrophyte In addition to the primary influence of water presence and frequency is provided in Section quality, other relevant physical attributes of stand- 6.3.2. Other methods for monitoring attributes of ing waters include the depth and profile of the open water bodies are given in Table 5.12. water body and its substrate type. Maintenance of Other important aspects of water chemistry that these conditions and an overall diversity of the influence the quality of standing water habitats physical forms is important. include the concentrations of dissolved oxygen, The vegetation of water bodies can change rela- ammonia, toxic substances such as heavy metals tively rapidly as a result of changes in water qual- (some of which may occur naturally, e.g. in acidic ity, which in turn can be very rapid as a result of waters), and pesticides. These cannot, however, be pollution incidents. Vegetation monitoring should regarded as direct attributes of standing water therefore be carried out fairly frequently, probably bodies, but are rather influencing factors that are, at intervals of no more than 3 years. Sampling of in turn, primarily influenced by external factors (e.g. appropriate water-quality determinants should be pollution). They should nevertheless be monitored carried out at least annually, with replicate sam- as they can have significant impacts on the condi- ples collected on a number of occasions during the tion of interest features. The monitoring of these peak growing season and preferably at other times water chemistry attributes is, however, a specialised as well, especially for water bodies known to be activity and the interpretation of results is complex subject to pollution. Phosphorus concentration (see Parr (1994) and Hellawell (1997) for reviews). It measurements during the growing season should is therefore recommended that specialist advice be include total phosphorus as well as soluble reactive obtained on such chemical analyses. phosphorus (SRP), as most SRP will be taken up by Water clarity is also an important factor, deter- growing phytoplankton and macrophytes. Water- mining underwater light intensities and hence the quality monitoring is carried out by the regulatory occurrence and vertical zonation of aquatic plants. authorities on water bodies over 1 km2 in size (and A simple relative measure of this can be obtained a small number of others); these authorities should by using a Secchi disc. Secchi discs are about 30 cm therefore be contacted when such monitoring is in diameter with alternating black and white or required, to establish what data are routinely col- yellow quarters. The disc is lowered slowly on a lected for the water body in question. 5.9 Standing open water 135

Table 5.12. A summary of the quality attributes providing an indication of the condition of open water bodies, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Aerial photography (Section 6.1.3) or satellite- properties based remote sensing (6.1.2) Structure Depth and profile Physical surveys with echosounders or depth lines (not covered) Substrate type Grab samples, subaqua or ROV inspections (not covered) Water Nutrient status, pH, dissolved oxygen, Trophic ranking score system (see text) or chemistry toxic substances, etc. chemical analysis (see text) Turbidity/underwater light Secchi disc or light meter (see text) Composition Community type NCC method (see text) or NVC for detailed surveys (6.1.6) Macrophyte abundance or species Quadrat or transect surveys by subaqua diving richness (Part III, Section 14.2.1) Grapnel surveys (6.3.2 or 14.2.1) Emergent vegetation Fixed-point photography (6.1.4), quadrat surveys (6.4.2 and 6.4.3) or transects (6.4.6)

Physical attributes are unlikely to change circumstances aquatic plant productivity in fresh- rapidly and therefore monitoring may only need water systems tends to be limited by phosphorus to be carried out at 5–10 year intervals, depending availability. Phosphorus-rich pollutants, such as on local circumstances. Additional and immediate run-off from cereal fields, farmyard slurry, manure monitoring may, however, be required if physical and silage seepage, and effluent from sewage treat- changes are known to occur at a site. See Table 5.12 ment works, are therefore the major causes of fresh- for a summary of the attributes indicating the con- water eutrophication (Klapper, 1991). However, dition of open water bodies and recommended nitrogen can become limiting in waters in which techniques for monitoring them. phosphorus concentrations are very high. An increase in nitrate concentrations, resulting from Management requirements and external impacts agricultural run-off following fertiliser application Many standing water bodies require no, or rela- or the ploughing of old grasslands, may therefore tively little, management to maintain their conser- contribute to eutrophication in such circumstances. vation interest. However, standing water bodies are The effects of eutrophication may also be exacer- increasingly subject to a number of detrimental bated by excessive water abstraction upstream lead- external impacts. ing to a reduction in the quantity of water reaching a Pollution is probably the main impact on stand- water body. This may increase nutrient concentra- ing waters but tends to differ between lowland and tions in the incoming water and increase residence upland water bodies (Alexander et al., 1997). time in the water body, thereby increasing the avail- Nutrient enrichment (eutrophication) from pollu- able time for nutrient uptake by plants. tion is the main impact on standing waters in Eutrophication is less of a problem in the uplands the lowlands because of the proximity of intensive because of the absence of intensive farming and agricultural activities and higher densities of human the low human population density. Instead, oligo- settlements. As described above, under most trophic lakes are prone to acidification from 136 5 HABITAT REQUIREMENTS AND ISSUES

pollutants in rain on account of their naturally low the suitability of various methods in relation to pH and poor buffering capacity. these and other considerations (such as the macro- Other threats include siltation, as a result of phytegrowthform)areprovidedinBell(1996). ploughing (for agriculture or forestry) or peat cut- Safety is clearly a key consideration when carry- ting on surrounding land, the introduction of alien ing out fieldwork at large water bodies. Key safety species of fish, and disturbance of waterbirds and measures that should always be followed include otters resulting from the use of water bodies for proper training of personnel in safety aspects of leisure activities. aquatic monitoring (especially in the use of These external factors should therefore be moni- boats); the correct use of appropriate safety equip- tored where appropriate, but in many cases these ment (e.g. life jackets when working over or along- are likely to be the responsibility of the regulatory side deep water); working in pairs or teams (never authorities and may already be covered by ongoing alone); and proper emergency planning (including monitoring programmes. notifying others of routes and expected return times when working in remote locations). Other 5.9.2 Specific issues affecting the safety precautions listed in Part I, Box 2.11, should monitoring of the habitat also be followed where appropriate.

The monitoring of freshwater habitats is a specialised subject and cannot be dealt with compre- 5.10 RIVERS AND STREAMS hensively here. In particular, assessments of 5.10.1 Surveying and monitoring water chemistry can be difficult and require specia- requirements and methods lised equipment. The interpretation of results in relation to the condition of and impacts on features Attributes for assessing habitat condition of interest is also complex. It is therefore recom- As with standing waters, river habitats exhibit a mended that specialist advice be obtained on these wide range of physical and biological variation, subjects. Further information on these can also be from headwater streams to mature reaches and obtained from some ofrecommended the sources estuaries. As a result of this variety and the special listed at the end of the book. character of these habitats, their attributes and As described above, general assessments of monitoring methods can only be outlined in this water quality by using macrophyte indicators are Handbook. Further information is available on these easier than chemical analyses. A method for moni- topics in the recommended reference sources toring macrophyte presence and frequency is listed at the end of the book. described in Section 6.3.2. Ten major types of river have been identified Thereareanumberofspecificpracticalconsid- and used as a basis for SSSI selection (NCC, 1989). erations to take into account when selecting This classification was initially based on a Two-Way appropriate methods for monitoring water INdicator SPecies ANalysis (TWINSPAN) of macro- bodies. In particular, the size of the water body phyte data from 1055 sites on over 100 rivers will considerably influence the efficiency of dif- throughout Britain, which identified 54 subdivi- ferent techniques and the resources required to sions (Holmes, 1983). This has since been recently sample it. Access is also an important consid- updated following a re-analysis and the addition of eration. Detailed and quantitative techniques data from a further 459 sites to the original dataset may be difficult or impossible to carry out along (Holmes et al., 1998, 1999a). The overall structure of deep tree-lined water bodies or on large shallow the new classification is the same as that of the first lakes. The distance from a road or navigable water- version. The highest level consists of four broad course may also restrict the use of some survey groups (A–D) representing an environmental gradi- methods; ROVs, boats, diving equipment, etc. are ent from lowland eutrophic rivers to those that are difficult to transport on foot. Tables summarising essentially upland, torrential and oligotrophic. 5.10 Rivers and streams 137

Group RCT Description

A I Lowland, low-gradient rivers II Lowland, clay-dominated rivers III Chalk rivers and other base-rich rivers with stable flows IV Impoverished lowland rivers B V Sandstone, mudstone and hard limestone rivers of England and Wales VI Sandstone, mudstone and hard limestone rivers of Scotland and northern England C VII Mesotrophic rivers dominated by gravels, pebbles and cobbles VIII Oligo-mesotrophic rivers D IX Oligotrophic, low-altitude rivers X Ultra-oligotrophic rivers

These four sub-groups are divided into 10 River A more constant measure of productivity is provided Community Types (RCTs) with subdivisions into by alkalinity, as indicated by the amount of calcium 38 sub-types (see later). carbonate dissolved in the water. Definitions of the Macrophyte communities are highly influenced various trophic categories according to nutrient sta- by water-flow regimes, water nutrient status and tus (Vollenweider, 1968) and alkalinity (Ratcliffe, substrate type. These factors tend to vary across the 1977) are given in Section 5.9. stages of a river as it flows from source to mouth. Other important aspects of water chemistry that Consequently, the classification, as described influence the quality of river habitats include below, reflects the different stages of a river as dissolved oxygen concentrations, ammonia con- well as its geology, water chemistry, substrate and centration, turbidity, and concentrations of toxic characteristic macrophyte communities. substances such as heavy metals (some of which Thus, although macrophyte communities may may occur naturally, e.g. in acidic waters), and pes- be the designated features of conservation interest ticides. These cannot, however, be regarded as within an SSSI or other site, other attributes of direct attributes of river habitats, but they are influ- nutrient status, pH and substrate should also be encing factors, which are in turn influenced by monitored (where feasible) as these are inherent external factors (e.g. pollution). They should never- and inseparable characteristics of each River theless be monitored as they can have significant Community Type. Similarly, underlying geology is impacts on the condition of interest features. also an inherent and inseparable characteristic, but The monitoring of water chemistry is a specia- this does not need monitoring as it is not expected lised activity and the interpretation of results can to change. be difficult (see Parr (1994) and Hellawell (1997) for The principal factor in controlling the nutrient reviews). It is therefore recommended that specia- status of freshwater ecosystems is the abundance list advice on such chemical analyses be obtained. and availability of phosphorus, as this normally Required data may also be collected by the envir- limits the growth of phytoplankton (free-floating onmental protection authorities as part of their unicellular algae) and macrophytes (other aquatic routine water quality monitoring programmes. plants) (Mainstone et al., 1993). Under certain cir- Alternatively, water quality can be assessed cumstances, nitrogen can be the limiting nutrient through macroinvertebrate indicators. This is, for aquatic plants, particularly if phosphorus con- however, a specialised technique and cannot be centrations are very high as a result of enrichment described here. A useful summary of the subject from sewage treatment works. However, the avail- can be found in RSPB/NRA/RSNC (1994); recent ability of plant nutrients changes with the season. reviews of the subject have been carried out by 138 5 HABITAT REQUIREMENTS AND ISSUES

Metcalfe-Smith (1994), Hellawell (1986, 1997)and reliability of the results: I–III indicate whether Wright et al. (1994). Information on techniques can paired sites being compared were physically com- be found in Part III,Chapter20; see also Hellawell parable; A–C indicate whether results may have (1978) and HMSO (1978, 1980, 1983). Macrophyte been affected by poor survey conditions or the identification guides are available in Croft (1986) effects of management; and a–c identify how and various Institute of Freshwater Ecology publi- many macrophyte species on the recording sheet cations (www.ceh.nerc.ac.uk). Again, the environ- were present. The greater the number, the better mental protection authorities should be contacted, the confidence in the results. as such data may be available as part of their moni- The MTR system has been used for monitoring toring programmes. water quality around effluent discharge points. As with standing waters, macrophytes may be Reviews of survey results have shown that the monitored to assess overall water quality (see method is effective and efficient. It performed Section 5.9 for advantages and disadvantages) as best on river systems that were not already well as their own condition as features of conserva- enriched prior to the discharge being monitored tion interest. Consequently, macrophytes have been and worst on extremely enriched river systems in widely used for monitoring the water quality of riv- which one more discharge makes very little differ- ers in Europe and the UK. The current technique for ence. Scores are distorted if two sites being com- this purpose being used in the UK is the mean trophic pared are not similar in physical character and rank (MTR) system (Holmes et al., 1999b) which devel- when few species that are used to calculate scores ops the earlier plant score system developed by the are present. The method has given good results Standing Committee of Analysts (1987). from clean oligotrophic rivers in south-west The MTR system is based on surveys of selected England and the Lake District. (usually common) aquatic macrophytes. These are A brief review of general monitoring methods assigned a number from 1 to 10 according to their for macrophytes is provided in Bell (1996). At its tolerance/preference for enriched or clean waters: simplest, monitoring may focus on confirmation of this is the species trophic rank (STR). Depending on the presence of a particular River Community the species cover value of listed taxa within a 100 m Type. This can be easily carried out by using the reach (recorded on a nine-point scale), a mean standard method for river macrophyte surveys trophic rank can be assigned. The method is developed by the NCC for its national survey of applied by surveying a 100 m length of river, pre- river communities. Full details of this are given in ferably by wading or a combination of wading and Holmes (1983) and Boon et al.(1996a,b, 2002). In walking along the banks in narrow rivers. Where essence, the survey method involves recording rivers are wadeable, or a boat can be used safely and macrophytes at sites 1 km long (formed from two effectively, the whole channel width should be sur- contiguous 500 m lengths), situated 5–7 km apart. veyed. For wide and deep rivers in which the cen- Surveys include the entire channel and lower tral channel is devoid of vegetation or cannot be slopes of the banks, with separate records being accurately surveyed because of its depth, turbidity, made for macrophytes that are more or less perman- etc., a strip 5 m wide down one side (ideally with ently submerged and those that are typically sub- little shading from trees) should be surveyed. If ject to alternate inundation and exposure with the water clarity is poor, a glass-bottomed bucket or rise and fall of river levels. Terrestrial plants with an underwater video camera should be used. no special affinity for rivers are excluded from the Surveys should be carried out once or twice a survey; although rare aquatic plants are recorded, year between June and September. From the stand- these are not used in the classification process. At ard list of species, cover values are estimated on a each site an estimate is made of the relative macro- nine-point scale, with 1 being less than 0.1% cover phyte abundance by using a simplified DAFOR-type and 9 being more than 75% cover. MTR calculations scale (1, rare; 2, occasional or frequent; 3, abundant have three suffixes of confidence to assess the or dominant) and a simple percentage cover scale 5.10 Rivers and streams 139

(1, <0.1%; 2, 0.1–5.0%; 3, >5%). Surveys are carried scales, i.e. catchment or sub-catchment scale. It is out by walking the banks and wading, or by boat therefore primarily used as a broad-scale conserva- for deeper rivers. However, the repeatability of this tion evaluation tool, although evaluations are car- technique and resulting consistency of classifica- ried out by dividing rivers into a series of evaluated tion is unknown, and it may be inadequate for all catchment sections (ECSs). Monitoring of each ECS but the most basic monitoring purposes. Certainly, may be carried out on the basis of scores from the the abundance and percentage assessments for each model or individual SERCON attributes. However, species are too subjective and crude for moni- assessments of these attributes are to some extent toring purposes. Vegetation composition monitor- subjective and therefore variation between repeat ing should instead be carried out by the surveys by different people may limit its value for appropriate adaptation of quadrat and transect monitoring compared with more objective and techniques (see Section 6.3 for bankside vegetation quantitative methods. A full SERCON assessment and Part III,section14.2.1, for aquatic vegetation). is also time-consuming, but SERCON is currently A method for monitoring aquatic plant assem- being revised; it is expected that version 2 will have blages by rake or grapnel samples in deep, slow- a slimmer variant as well as the full version. flowing rivers is outlined in Section 6.3.2. Maps of However, some SERCON attributes could form a the cover of individual species may be appropriate useful suite for monitoring. for small stretches of shallow rivers. Mapping may General monitoring of morphological attributes be time-consuming, but it provides detailed and of rivers can be carried out by using River Habitat reproducible results that can justify the effort. Survey methods (see Section 6.3.1.) More detailed Further information on this technique is provided and accurate monitoring of the extent of these in Standing Committee of Analysts (1987) and attributes will probably need to be carried out by Wright et al. (1981). the adaptation of other methods such as fixed- Other key features of river habitats include point photography (Section 6.1.4), quadrats and important morphological and hydrological attri- transects (Section 6.4 and Part III, Section 14.2.1) butes, such as channel width, depth, slope, capacity, or by specialised monitoring techniques that can- substrate type, flow velocity and flow rate (and its not be described here. seasonality) and the presence of various important Monitoring the hydrological attributes of a river, habitat features, such as riffles and pool sequences, such as flow rates, is complex, time-consuming and bars, meanders and waterfalls, etc. The effects of expensive. However, sufficient information neces- such attributes on river ecology are complex but sary for basic conservation monitoring purposes is these, together with biological data, have been likely to be available from the environmental pro- recently incorporated in a model that provides a tection authorities. comprehensive and integrated assessment of river A summary of river attributes that require moni- conservation value: SERCON (System for Evaluating toring is provided in Table 5.13, together with Rivers for CONservation). SERCON utilises existing recommended methods for monitoring each. habitat and species data for a range of river corridor These are described more fully in Chapter 6. attributes to apply classic conservation assessment criteria, such as diversity, naturalness, representa- Management requirements and external impacts tiveness and rarity, but in a more rigorous manner High human population density and the presence of than has been done in the past (Boon et al., 1996a,b). intensive agriculture directly affects river condition For the assessment of many river corridor attri- and water quality. The frequency of rivers affected butes SERCON depends on outputs from River by, or at risk from, organic and chemical pollution Habitat Surveys (Environment Agency, 2003) or, from agriculture, domestic wastes and industry gen- rarely, River Corridor Surveys (NRA, 1992) unless erally increases in the lowlands (and in some areas similar data are available from other sources. towards the coast) as the land is more densely popu- Generally, SERCON is intended to work at large lated, agriculture is more intensive and industry is ) )or 6.4.3 ), 6.4.3 and ) for detailed and 6.4.2 ) or mapping for ) or satellite-based ), line transects or ) for detailed studies 6.1.3 ) or fixed-point photography 6.1.4 14.2.1 6.3.1 or ) ) or quadrat methods ( 6.1.2 ) for detailed studies 6.4.6 6.4.6 ) for general surveys, quadrats (6.4.2 6.1.4 Obtain from environmental protection authorities remote sensing ( River habitat surveys ( Fixed-point photography ( transects ( Obtain from environmental protection authorities or use mean trophic rank systemmacroinvertebrate (see indicators text) (see or text) ( quadrat methods (6.4 Grapnel surveys in slow moving deep water (6.3.2 studies Line transects ( Aerial photography (Section quadrat or transect surveys (14.2.1 detailed studies in shallow water (see text) Monitoring technique NCC method (see text) or NVC surveys (6.1.6 of rivers, and their recommended monitoring techniques substrate type, presence of riffles, pools, meanders, water control structures, etc. Coverage of banks and watercourse Vegetation height substances, etc. Habitat properties Aquatic macrophyte species abundance or richness Bankside and emergent vegetation species abundance or richness Channel width (bank, full and low flows), shape, Nutrient status, pH, BOD, dissolved oxygen, toxic e.g. water flow rates and depth A summary of the quality attributes providing an indication of the condition Attribute Table 5.13. Physical properties Extent River morphology Vegetation extent and structure Water chemistry Hydrology Vegetation composition River community type

140 5.11 Montane habitats 141

more common. This may also be exacerbated by monitoring (especially in the use of boats), the cor- water abstraction as this may lead to low flows, rect use of safety equipment (e.g. life jackets when which can contribute to high pollutant concentra- working over or alongside deep water) and work- tions and reduced dissolved oxygen concentrations. ing in pairs or teams and never alone. Other safety Overall pollution impacts may, however, be less in aspects listed in Part I, Box 2.11, should also be downstream sections on account of the dilution of followed where appropriate. pollutants by large volumes of water. Special care should be taken when working on In the upstream reaches and headwaters, pollu- rivers that are liable to rapid changes in flow. tion may occur from various types of discharge and domestic waste. The ploughing and/or drainage of moorland for forestry and agriculture can lead to 5.11 MONTANE HABITATS high levels of silt and peat run-off, which increases 5.11.1 Surveying and monitoring the turbidity levels of the water. Oligotrophic and requirements and methods acid waters are also particularly susceptible to acidification from acid deposition. Attributes for assessing habitat condition In addition to pollution and abstraction pro- Montane sites include a range of habitats above the blems, management actions may have detrimental natural tree line. Ninety per cent of the UK resource effects on the conservation interest of rivers. In occurs in Scotland. Information on the monitoring particular, flood defence measures such as bank of many of the habitats present in the uplands is strengthening and canalisation, removal of riparian covered elsewhere (scrub in Section 5.1; grasslands vegetation, dredging, and the installation of water in Section 5.4; heathlands in Section 5.6; wetlands control structures such as weirs, can have profound in Section 5.7; streams and pools in Sections 5.9 impacts on river morphology and in turn on their and 5.10; and blanket bogs in Section 5.12). Only a biological interest. Fisheries management and brief account is therefore provided here. recreational activities can also have impacts Key attributes of importance to montane habitats through habitat modifications, disturbance and, in are physical features such as bare cliffs, rocks, scree the former case, the introduction of alien species or and soil and the prolonged presence of snow artificially increased populations of native fish. patches. Montane vegetation types are rather distinct and often rare in the UK, such as alpine calcar- 5.10.2 Specific issues affecting the survey eous grassland. Montane habitats commonly occur and monitoring of habitat in mosaics to form habitat complexes of particular collective importance for their flora. Species compo- As with standing waters, the monitoring of rivers is a sition can be very important, with many relict specialised subject and therefore it is recommended Arctic–alpine and endemic species occurring. that specialist advice be obtained before planning A summary of the key attributes that require mon- and implementing a monitoring programme for itoring is provided in Table 5.14,togetherwith these habitats. See Section 5.9 for a discussion of recommended methods for monitoring each. practical considerations regarding monitoring of water bodies. As described above, routine monitor- Management requirements and external impacts ing of water quality and various hydrological factors Montane vegetation is particularly vulnerable to is carried out on many rivers by the environmental heavy grazing (Section 7.1), accidental burning protection authorities. Relevant data may therefore (Section 7.2), erosion (Section 7.3) and air pollution. be available for some sites. Montane habitats are known to be sensitive to air Safety is clearly a key consideration when carry- pollution and acidification, so maintaining an ing out fieldwork on rivers. Key safety measures acceptable condition in the long term will require that should always be followed include proper pollution climates below the critical concentra- À3 À3 À3 training of personnel in safety aspects of aquatic tions (SO2 10 mgm ,NO2 30 mgm ,NH3 8 mgm ) 142 5 HABITAT REQUIREMENTS AND ISSUES

Table 5.14. A summary of the quality attributes providing an indication of the condition of montane habitats, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I mapping (Section 6.1.5) with aerial properties photography (6.1.3) for basic long-term monitoring NVC surveys with quadrat sampling (6.1.6) for NVC vegetation types Exposed rock, scree and bare soil, Aerial (6.1.3) or fixed-point (6.1.4) photography, and snow lie quadrats (6.4.2) or transects (6.4.6) Soil nutrients 6.2.2 Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition and Mini-quadrats (6.4.3) richness Presence/absence of Look–see or total counts (Part III,sections15.2.1 and typical/indicator species 15.2.2,) quadrats (6.4.2 and 6.4.3) or transects (6.4.6)

(English Nature, 1993). These aspects should there- The complexity of some sites means that strati- fore also be monitored though, as it may be diffi- fied sampling will be required and will have to be cult to monitor air pollution directly, data may carefully designed to efficiently cover the range of need to be drawn from wider-scale models. habitats and their localised variations. On account of the large size of sites and the time required to 5.11.2 Specific issues affecting the move between samples, multi-level sampling may surveying and monitoring of habitat be appropriate (Part I, Section 2.3.) If permanent quadrats are to be used, frost heave It is recommended that uplands are monitored at 3 may result in loss of markers. Using good location or 6 year intervals. They are almost always best features, such as large boulders, and making surveyed in July and August when the weather is detailed measurements may be very helpful for better and the vegetation fully developed. Access relocating quadrats. Rock climbing bolts have been may be difficult late in the season because of deer used as markers but are now considered unsightly. stalking or grouse shooting. Scree slopes are often mobile; permanent quadrats When planning surveys allow at least 1 day lost are therefore inadvisable on this habitat. to bad weather for each survey day. The logistics of For assessing changes in many features of the getting equipment into place can be very difficult; vegetation, such as species richness and sward often, cursory surveillance may be the best option. height and cover, the techniques outlined in Aerial photography (Section 6.1.3) may be cost- Section 5.4 can be applied. The hanging quadrat effective for large areas. technique may be useful for recording quadrats Determining your location may be very difficult on vertical surfaces (Rich & Matcham, 1995). in wet weather, and especially on large uniform Unfortunately, the NVC does not cover lichen upland areas is virtually impossible from maps. and bryophyte vegetation, and there is no work- Global positioning systems (GPS) have distinct able account of these vegetation types available. advantages, despite their inaccuracies (although James et al.(1977) give a preliminary conspectus these are substantially improving over time). of lichen communities, which may be of some 5.12 Blanket bog 143

use for some communities. The specialist upland High water tables are essential for bogs to be bryophytes and lichens also require expert active (i.e. forming peat); most bogs have water botanists. tables near the surface except in drought condi- The persistence of snow patches varies from tions. However, monitoring water tables alone is year to year, but snow cover has usually gone by not sufficient, even if it could be achieved in a late July. The snow often acts to catch nutrients meaningful way, and assessments of whether the from wind-blown vegetation, and snow patches bog is forming peat are also important. On account are thus often relatively nutrient-rich compared of the slow rate of peat accumulation (in the region with surrounding ground. of 10 cm over 100 years), it is not practicable to Alpine cliffs and rocks can support rich plant assess this by measuring peat depth and rates of communities. These habitats are dangerous to peat accumulation. Instead, it is normally assumed work on and often unstable. Roped-access work from the active growth of Sphagnum. The presence may be required for critical areas, but is very of characteristic Sphagnum species can be used to time-consuming. Particular care should be taken infer the occurrence of active peat formation. In when working in montane areas; all relevant safety general, if the Sphagnum is healthy and growing, recommendations outlined in Part I, Box 2.11, the habitat should be in good condition. Other should be strictly followed where appropriate. typical species indicative of peat formation capability are often locally important on blanket bogs, and appropriate species may be selected on a site basis. 5.12 BLANKET BOG For example, in the north and west Racomitrium 5.12.1 Surveying and monitoring often replaces Sphagnum as the dominant bryo- requirements and methods phyte, and Cotton Grass Eriophorum vaginatum is an important peat-forming species on many high- Attributes for assessing habitat condition altitude bogs. Under a number of conditions (such as suitable In wet, humid climates the vegetation may be rainfall–evapotranspiration regime and topog- dominated by Sphagnum, but in drier conditions raphy), blanket bogs often occur as the dominant there is usually more Heather Calluna, Cross- habitat type within extensive landscapes, and may leaved Heath Erica tetralix, Eriophorum spp. and form mosaics with other vegetation types; such Deer Grass Trichophorum spp.. The significance of extensive blanket bog landscapes are of particular different species varies with altitude, longitude importance. Habitat extent is therefore a key and latitude. A significant proportion (perhaps attribute. more than 10%) of Sphagnum in the main bog com- The physical structure of bogs is also considered munities is considered to indicate active peat for- to define their condition and therefore there are mation. Locally determined cover proportions several structural attributes that should be moni- should be derived from analysis of existing quadrat tored. It has been suggested that blanket bogs data and other historical observations. Similarly, require at least 0.5 m of peat (NCC, 1990a)toseparate proportions of other species may be derived from the vegetation communities from the underlying existing data. substrate and provide the appropriate hydrological Certain NVC bog communities can also indicate and chemical conditions for Sphagnum growth, good, relatively undisturbed blanket bogs, depending although many have on average 2–3 m of peat. to some extent on geographical location (Rodwell, Some blanket bogs may also have shallower peat 1991,vol.2).TheM17Scirpus cespitosus–Eriophorum areas because of their topography. Ideally, the vaginatum blanket mire, often associated with the peat mass should be intact, but most bogs have M1 Sphagnum auriculatum bog pool community in been damaged to some extent by cutting, drainage, the pools or wettest areas, is the characteristic blan- burning, grazing, erosion, afforestation or agricul- ket bog type in oceanic parts of Britain, generally at tural improvement (see below). low altitudes. The M18 Erica tetralix–Sphagnum 144 5 HABITAT REQUIREMENTS AND ISSUES

papillosum raised and blanket mire occurs over A summary of attributes providing an indication large areas in Caithness (A. Coupar, personal com- of the condition of bog habitats and their recom- munication) on cols and in depressions (Rodwell, mended monitoring methods is given in Table 5.15. 1991) and has associated areas of the M2 Sphagnum It is recommended that bogs be monitored at cuspidatum/recurvum bog pool community. The 3 to 6 year intervals. M15 Scirpus cespitosus–Erica tetralix wet heath may occur in naturally better drained areas at the bog Management requirements and external impacts margin. The M19 Calluna vulgaris–Eriophorum vagi- The management of bogs can markedly affect their natum blanket mire is dominant on high-level quality. Grazing, burning and drainage can all blanket bog. NVC-based survey and monitoring damage the vegetation, and even trampling can is, however, by itself too general to differentiate affect Sphagnum cover. Under natural conditions between good and poor bog communities (such as the blanket bogs are likely to have been lightly M18), being particularly insensitive to changes in grazed. Information on indicators of drying, burn- structural attributes (e.g. as a result of grazing). ing, grazing and trampling are given in MacDonald Interpretation of the presence of so-called et al. (1998a,b). ‘degraded’ communities should also be under- Air pollution (especially sulphur-based pollu- taken with care. tion) is known to damage Sphagnum communities Woody species (except Salix repens, Betula nana, so maintaining an acceptable condition in the long Vaccinium spp. and Bog Myrtle Myrica gale)are term will require pollution regimes below the criti- À3 À3 generally not considered to be natural components cal concentrations (SO2 10 mgm ,NO2 30 mgm , À3 of blanket bogs. Therefore, invasion by other birch, NH3 8 mgm )(EnglishNature,1993). willow or other woody species should be moni- Stoneman & Brooks (1997) provide management tored, although this may indicate surface flushing advice for blanket bogs. (unlikely) and the absence of grazing and burning, rather than a drying out of the bog. 5.12.2 Specific issues affecting the survey Lastly, structure is very important in blanket bogs and monitoring of habitat in determining hydrological functioning and the presence of different features and niches. At a Bogs should be surveyed from July to September large scale, individual blanket bog units (mesotopes) when their vegetation is fully developed, although occur in a range of topographical positions such as all attributes other than those pertaining to watersheds, valley sides, spurs and saddle mires. deciduous species can be monitored at other These often form inter-related complexes (macro- times of year. topes) of greater interest than individual mesotopes. Wet bog habitats can be very sensitive to tram- Within each mesotope it is also natural to have pling and there is therefore a considerable risk of variation in the communities present related to var- damage from monitoring activities. Methods iations in topography, hydrology and substrate fea- should be chosen appropriately, according to local tures, including transitions to vegetation on conditions. In general, permanent quadrat or trans- mineral soils. Pool and ridge patterning in some of ect methods should be avoided and disturbance of the northern bogs is of particular interest. All bogs the bog surface kept to a minimum. In particular, display some form of surface patterning, which on vulnerable habitats, automated or remote moni- represents an important source of biodiversity. toring techniques should be used where appropri- Most relatively undisturbed bog surfaces usually ate. The number of sampling locations should also show distinctive fine-scale variation (microtopes) be kept to the minimum necessary and the interval with small drier hummocks and wetter hollows between sampling occasions should be as long as related to growth of Sphagnum and other plants, possible. although the large-scale features may be highly As mentioned above, bog habitats can be very restricted or locally frequent. extensive and this raises a number of problems. In 5.13 Maritime boulders, cliffs and slopes 145

Table 5.15. A summary of the quality attributes providing an indication of the condition of blanket bog, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I mapping (Section 6.1.5) with aerial photography properties (6.1.3) (or satellite-based remote sensing (6.1.2) for very large sites). NVC surveys with quadrat sampling (6.1.6) for detailed studies Water table Dipwells or WALRAGS (6.2.1) Bare peat Aerial photography (6.1.3), quadrats (6.4.2 and 6.4.3)or transects (6.4.6) Peat depth Soil augers or levels from mineral ground Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition and richness Mini-quadrats (6.4.3) (quadrat size depending on scale of vegetation) Presence–absence of typical or Look–see or total counts (Part III, Sections 15.2.1 and indicator species 15.2.2), quadrats (6.4.2 and 6.4.3) or transects (6.4.6). Structure Landscape and habitat mosaics Aerial or fixed-point photography (6.1.3 and 6.1.4) Structural features (pool and Conventional quadrats (6.4.2) or transects (6.4.6). hummock, and/or hollow and Photographs from vantage points may be useful (6.1.3 ridge as appropriate) and 6.1.4) Dynamics Peat formation Quadrat- (6.4.2 and 6.4.3) or transect- (6.4.6) based assessment of indicator species particular, vehicular access is likely to be impossi- compartments for monitoring purposes (Part I, ble, and is in any case undesirable because of the Section 2.1.7.) potential for lasting, if local, damage. A consider- The size, remoteness and extreme weather con- able amount of time is likely to be spent walking to ditions of many bog sites also raise potentially monitoring locations. Sampling strategies should significant safety problems. Safety protocols (see therefore be designed with this in mind, using Part I, Box 2.11) should therefore be strictly fol- techniques such as multi-stage sampling (Part I, lowed. In particular, personnel should not carry Section 2.3.4). Automated monitoring techniques out monitoring alone at remote sites and should (e.g. for water levels) may also be cost-effective be properly equipped and trained. but should only be used in very specific circumstances, e.g. the monitoring of a consented, but potentially damaging activity. Similarly, expensive 5.13 MARITIME BOULDERS, ROCKS, remote methods such as aerial photography (or for CLIFFS AND SLOPES very large sites, satellite-based sensing) may be 5.13.1 Surveying and monitoring financially viable. requirements and methods Variations in topography, hydrology and other physical properties can lead to considerable hetero- Attributes for assessing habitat condition geneity in bog habitats. As a result, it may often be The 4000 km of sea cliffs in the UK are a major necessary to subdivide large and complex sites into nature conservation resource of international 146 5 HABITAT REQUIREMENTS AND ISSUES importance. They are important as extensive areas of Management requirements and external impacts natural habitat, which is often relatively little An account of sea cliffs and their management affected by human activity. Some cliffs have import- has been presented by Mitchley & Malloch (1991). ant geological exposures, but the geological, botani- The main management tools are grazing, mowing cal and zoological interests may not coincide. Cliff and burning, although much of the lower parts habitat, as defined here, includes all the vegetation of cliffs are inaccessible and do not need to be types in the NVC sea cliff vegetation chapter of managed. Rodwell (2000, vol. 5), from the vegetation of vertical The main problem in maintaining the area of sea sections at the base of a cliff to the flatter top parts. cliff is that the upper edge is usually valuable farm- The extent of the sea cliff habitat is not easy to land, which is expensive to use as a replacement for measure because vertical projections are not repre- areas lost to erosion. The most practical measure to sented well on maps, although in practice often the maintain area may be to ensure that no further upper parts of cliffs are slopes and only the lower truncation of the inland margin of the cliff vegeta- parts are vertical. Natural erosion of cliffs results in tion occurs, and accept loss on the seaward side. regular loss of area. Rather than monitoring loss of The main threats to sea cliffs are agricultural activ- material to the seaward side (which could be moni- ities, tourism, and coastal development and protec- tored by photographs from the sea), it may be best tion. Coastal protection works or uncontrolled to concentrate on monitoring loss to agriculture, dumping may prevent erosion and affect coastal pro- etc. on the inland side. cesses, leading to loss of interest. There may be some Coastal sea cliff vegetation and species composi- risk from accidental fires, although this has probably tion are important factors to monitor, as they are decreased with the cessation of stubble burning. Oil the basis of this unique habitat. The vegetation pollution may be a serious risk in some places close often shows marked zonation depending on geol- to shipping lanes; the lower cliff communities may ogy, erosion, geographical location and especially be seriously affected by oil deposition. the degree of exposure to wind and salt spray. The lowest zones are primarily occupied by lichens and 5.13.2 Specific issues affecting the survey some bryophytes, which grade into higher plant and monitoring of habitat vegetation above. In some exposed sites the clifftop vegetation grades into maritime heath, grassland It is recommended that cliffs be monitored at 3 or and scrub, which form an integral part of the cliff 6 year intervals. They can be surveyed between May habitat, but in many cases they are truncated by and October, although if annual species are import- agriculture or development inland. Soft cliffs often ant they should be surveyed in early summer. This display a much wider range of vegetation than that may conflict with the bird nesting season. included in the NVC maritime cliffs section, and Salt deposition during summer storms may have much of it is of nature conservation interest. a dominant influence on the zonation of the vege- The most important influence on the habitat is tation and cause the death of some areas. It may be the amount of salt spray, which is strongly influ- worth monitoring salt deposition if damage is also enced by situation and exposure. On the accessible expected from herbicides etc. used on adjacent upper parts of the cliff top, where salt deposition is farmland. weakest, structure and composition may be Unfortunately, the NVC does not cover lichen strongly affected by management, especially graz- and bryophyte vegetation, which is predominant ing. The soil sodium : organic content ratio is a at the lowest levels on cliffs; the best available useful yardstick for assessing the influence of account of these vegetation types available is spray (Rodwell, 2000). Table5.16 gives a summaryJames et al.(1977). The specialist maritime bryo- of the attributes providing an indication of the phytes and lichens also require expert survey. condition of maritime habitats and their recom- As vegetation composition is often strongly mended monitoring methods. related to soils and topography, careful stratification 5.14 Shingle above high tide 147

Table 5.16. A summary of the quality attributes providing an indication of the condition of maritime habitats, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I mapping (Section 6.1.5) with aerial photography properties (6.1.3) for broad long-term changes NVC surveys with quadrat sampling (6.1.6) for detailed studies Soil salinity Soil analysis (6.2.2) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition and richness Mini-quadrats (6.4.3) Presence–absence of typical or Look–see or total counts (Part III, Sections 15.2.1 and indicator species 15.2.2), quadrats (6.4.2 and 6.4.3) or transects (6.4.6) Structure Zonation between vegetation types Transects (6.4.6), fixed-point (6.1.4) or aerial photography (6.1.3) Pattern within vegetation types Quadrat sampling (6.4.2 and 6.4.3), fixed-point photography (6.1.4) may be required to ensure that the range of quality and extent is adequately covered. 5.14 SHINGLE ABOVE HIGH TIDE Generally, the upper limit of cliff vegetation is 5.14.1 Surveying and monitoring markedbyachangetoagricultureordevelop- requirements and methods ment, but in some localities there may be natural transitions to moorland. The influence of the sea Attributes for assessing habitat condition and salt declines with increasing distance from The major vegetated shingle structures of Britain the sea and decreasing exposure, and it may be have been reviewed in detail by Randall (1989) and difficult to define the inland edges. If permanent Sneddon & Ranwell (1993, 1994). There are esti- markers are required, these are best established at mated to be 6115 ha in the UK. These may be of the landward edge on sites with significant considerable interest for their geomorphology in erosion. addition to their distinctive plant and animal Safety considerations may prevent detailed map- communities. ping of vegetation for monitoring. There are severe In general the extent of shingle should be rela- practical difficulties in mapping vertical cliffs, tively easy to monitor on the inland edge, though especially on crumbly rocks. Rope work may be the shore edge may be more dynamic. The develop- required and this must be carried out by adequately ment of a shingle beach is dependent on a supply of trained personnel using appropriate equipment. sediment and waves, winds and tidal currents. The hanging quadrat technique may be useful for Much material may be lost or supplied naturally recording quadrats on vertical surfaces (Rich & during storm episodes, but some loss may also Matcham, 1995). For assessing changes in many occur through shingle extraction or indirectly as a features of the vegetation, such as species richness result of coastal protection elsewhere. The supply and sward height and cover, the techniques out- of shingle to the site by natural processes is best lined in Section 5.4 can be applied. For dwarf monitored from continued measurements of ero- shrub heath, see Section 5.6. sion or accretion at fixed points and may need to be 148 5 HABITAT REQUIREMENTS AND ISSUES assessed over decades. Mass movement of shingle Management requirements and external impacts to or from a site is very difficult to quantify. Most shingle sites do not require management. The vegetation types present are key attributes. However, human pressures such as coastal defence Shingle habitats include open pioneer stages close works, development, shingle extraction and to the sea, and grassland, heaths, scrub and moss- recreational activities may need some monitoring. and lichen-dominated vegetation on very old, Shingle extraction has affected some sites and is stable shingle further inland. Near the shore the probably the single most damaging activity. vegetation is typically open with many maritime Military and tourism activity has also damaged species. These decrease in abundance away from some sites. Grazing may result in the loss of some the shore as inland species increase. The NVC types sensitive taxa, but most sites are ungrazed. Oil pol- have been revised by Sneddon & Ranwell (1993), lution may occur at some sites. whose classification provides more detail than the Shingle banks may be coastal defence features in NVC but requires rationalisation. Some sites may their own right, and they are often maintained by be important for lichens; undisturbed shingles may supplies of shingle from further up the coast. have their own distinctive communities ( James Coastal defence works elsewhere may therefore et al., 1977), which may require monitoring in starve some sites of their supplies. their own right. Salinity, hydrology, and the stability, morphology and composition of the shingle are principal 5.14.2 Specific issues affecting the survey factors determining vegetation composition. and monitoring of habitat Strong patterning within the vegetation may It is recommended that shingle sites be monitored occur related to shingle ridge structure, with dis- every 3 years. Measurements of growth or loss of tinct lines of Crambe or Glaucium on the shingle shingle should be made every decade. Sites are best ridges. These patterns may become blurred as monitored between May and October, but nesting humus builds up in the shingle and is colonised birds may restrict access. Mapping can be difficult by additional plants. For invertebrates this struc- in uniform shingle structures, but is often rela- turing of the vegetation and small-scale mosaics tively traightforward provided details of topography are more important than its composition. are available. Aerial photographs can be invaluable. There may be strong zonation from the shore to the inland edge that is of considerable interest. The vegetation of the foreshore is strongly controlled 5.15 SAND DUNES AND STRANDLINE by the environment and only physical damage will VEGETATION markedly affect it. Chance determines which spe- 5.15.1 Surveying and monitoring cies colonise the foreshore. Transitions to inland requirements and methods communities are often truncated by anthropogenic activities, or shingle communities may grade into Attributes for assessing habitat condition rocky or sandy habitats. Sites with a range of com- Sand dune vegetation includes strandlines, dunes, munities, including pioneer communities, are dune slacks, dune heath and scrub. The different especially valuable. types form a complex, dynamic, sensitive ecosys- Shingle sites are often associated with other spe- tem capable of rapid change, and each part creates cial interest habitats, such as lagoons, sand dunes its own problems for monitoring. Because of the and saltmarshes, and the transitions between them dynamic nature of sand dunes and their associated can be of interest. The hydrology is often important vegetation, long-term (10 year) views on the for lagoons and saltmarshes. Table 5.17 sum- amount of each habitat and natural succession marises the attributes indicating the condition of between them should be taken. shingle, together with recommended techniques There is a significant amount of information for their monitoring. available on the extent and composition of sand 5.15 Sand dunes and strandline vegetation 149

Table 5.17. A summary of the quality attributes providing an indication of the condition of shingle, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I (Section 6.1.5), NVC surveys with quadrat properties sampling (6.1.6), fixed-point (6.1.4) or aerial photography (6.1.3) Hydrology Piezometers, dipwells or WALRAGS (6.2.1) Salinity Soil analysis (6.2.2) and water chemistry analysis (not covered) Topography and land loss Level surveying or fixed-point height surveys (not covered), aerial photography (6.1.3) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes (see also Sneddon & Ranwell (1993) community types) Species composition and richness Mini-quadrats (6.4.3) Presence/absence of Look–see or total counts (Sections 15.2.1 and 15.2.2), typical/indicator species quadrats (6.4.2 and 6.4.3) or transects (6.4.6) Zonation between vegetation types Transects (6.4.6), fixed-point (6.1.4) or aerial photography (6.1.3) Structure Pattern within vegetation types Quadrat sampling (6.4.2 and 6.4.3), fixed-point photography 6.1.4( )

dunes (see, for example, Dargie, 1993). Although monitoring, and different attributes will be required the overall extent is relatively easy to monitor, for different parts of the dune system. the proportions of NVC types within each system The percentage cover of vegetation usually can be very difficult to follow reliably as a result of increases inland and the extent of bare sand the intrinsic difficulties of surveying a complex decreases. Bare sand can give a good indication of habitat, the natural rate of change and the natural the likely stability of dunes and indicate grazing or continual gradation between the dune commu- public pressure, but occasional erosion of stabi- nities. The typical standardised succession from lised dunes may occur naturally and is central to strandline to yellow dune to grey dune to fixed long-term maintenance of slacks. dune, and to dune heath in some sites, can be used Sand dunes decrease in salinity and pH and as a framework for understanding the dynamics of increase in organic content with increasing dis- the system, but the whole sequence is rarely seen in tance from the sea. Nutrients are usually low practice. Typically the vegetation patterns are throughout except on the strandline. Soil analysis strongly related to topography, soil pH, water can therefore provide valuable information table, nutrient availability and grazing. There are directly relevant to the vegetation types. The usually extensive mosaics forming complex pat- water table is also very important for determining terns across the dunes, and within each part there the distribution of slacks and their associated vege- may also be mosaics of vegetation. These complex- tation, and may be worth monitoring if water ities mean that a very clear set of requirements abstraction is increasing. Water will vary in salinity must be set out before attributes are selected for depending on the local hydrology. 150 5 HABITAT REQUIREMENTS AND ISSUES

Given the importance of grazing to dune sys- recolonisation from a few permanent major tems, it is worthwhile monitoring some aspects of donor sites or as a patchwork mosaic of extinction grazing, such as stocking densities, at the same and recolonisation, and may require monitoring time as other features (see Section 7.1). A summary annually (a long-term view of the occurrence of of attributes giving an indication of the condition these must also be taken, such as over 25 years). of sand dune and strandline habitats and their Different parts of the dune systems may need to be recommended monitoring methods is provided in monitored at different times of year; for example, Table 5.18. slacks and strandlines are best monitored in July and August, whereas yellow dunes are best moni- Management requirements and external impacts tored in May and June while annual plant species The main management tools on dunes are grazing are still present. and scrub clearance. The structure of individual As the composition of dune vegetation is often stands is largely determined by grazing, the inten- strongly related to soils and topography, careful sity of which is site-specific and requires careful sampling stratification may be required to ensure adjustment. Undergrazing results in rank grass- that the full range of communities is adequately land and development of scrub, whereas heavy and efficiently covered. For assessing changes in grazing results in few flowers, poaching, erosion many features of the vegetation, such as species and uniform turf. Both Rabbit Oryctolagus cuniculus richness and sward height and cover, the techni- grazing and low nutrient concentrations are ques outlined in Section 5.4 can be applied. For important for the maintenance of diversity on dwarf shrub vegetation see Section 5.6, and for some dune systems. slacks much of the fen section (5.7) will be relevant. Oil pollution episodes can have dramatic effects Orientation on dune systems while monitoring on strandlines on account of both the toxic effects of can be extremely difficult, even with good topo- the oil and the effects of the clean-up operation. Tidy graphic maps. Permanent markers are notoriously beach campaigns (for the prestigious ‘Blue Flag’ difficult to re-find and frequently become under- awards) can also significantly damage strandline mined or buried by sand. habitats if cleaning is carried out mechanically, but some cleaning of human rubbish by hand must be made acceptable in some sensitive areas: unsightly 5.16 SALTMARSH rubbish needs to be removed in order to improve 5.16.1 Surveying and monitoring habitat condition (Llewellyn & Shackley, 1996). requirements and methods The major threats to dune systems are coastal protection, tourism, golf courses, afforestation, Attributes for assessing habitat condition land claim for agriculture, sand extraction, military There are estimated to be about 44 370 ha of salt- use and access roads (Ranwell, 1972;Doody,1985). marsh in Britain, occupying about 10% of the coast- The major causes of erosion on many dune systems line (Burd, 1989). are human feet and vehicles. Coastal defence works Saltmarshes are dynamic habitats; natural may also affect the supply of sediments and alter change in extent is to be expected. They may be coastlines, with knock-on effects for the occurrence subject to periods of sediment erosion or accretion. of these habitats. All these may require monitoring. Sediment movement patterns may be quite complex. Larger saltmarshes are intrinsically more 5.15.2 Specific issues affecting the survey valuable than smaller ones because of the and monitoring of habitat increased range of habitats within them and the lesser disturbance occurring at the upper edges. It is recommended that dune systems be moni- The development of small steps or edges at the tored at 3 or 6 year intervals. The strandline com- outer margin of the marsh is usually an obvious munities act as metapopulations, with repeated sign of erosion. Accretion can be monitored by 5.16 Saltmarsh 151

Table 5.18. A summary of the quality attributes providing an indication of the condition of sand dunes and strandline vegetation, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I mapping (Section 6.1.5) with aerial properties photography (6.1.3) NVC surveys (6.1.6) with quadrat (6.4.2) or belt transect (6.4.6) sampling or fixed-point (6.1.4) photography Topography and sand Level surveying or fixed-point height surveys accumulation/erosion (not covered), aerial or fixed-point photographs (6.1.3, 6.1.4) pH and nutrient content of sand Soil analysis (6.2.2) Water table Dipwells (6.2.1) Ground-water salinity Conductivity meters (6.2.2) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition and richness Mini-quadrats (6.4.3) Presence–absence of typical or Look–see or total counts (15.2.1, 15.2.2), quadrats indicator species (6.4.2, 6.4.3) or transects (6.4.6) Structure Percentage bare sand Quadrats (6.4.2–6.4.4), transects ( 6.4.6) or aerial photography (6.1.3) Tidal litter Quadrats (6.4.2–6.4.4) or transects (6.4.6) Dynamics Zonation Transects (6.4.6), fixed-point (6.1.4) or aerial (6.1.3) photography measuring the increased height of a marsh relative inland end of coastal-linked lakes, lochs and estu- to fixed points, or the extension of its outer edge. aries and natural communities inland are valuable, Extent is thus a key factor in monitoring but is but sites have often been truncated by sea walls, subject to long-term natural changes. land reclamation or agriculture. Saltmarshes are quite complex habitats and pro- Many saltmarshes are dissected by small creeks vide a range of attributes that can be measured, and channels, which provide microhabitats within depending on the monitoring objectives. Natural more uniform areas of marsh. The upper levels of changes in species and vegetation may occur, ungrazed or lightly grazed marshes are usually coupled with changes in the sediments. It should relatively rich in species, at least partly as a result be possible to monitor the range of vegetation of the range of microhabitats present, but lower types present on saltmarshes fairly simply; most marshes are intrinsically relatively species-poor. sites have been mapped by using a simplified vege- Some inland species may also occur near the top tation survey (Burd, 1989). Species composition can of weakly saline marshes. Salt pans and small pools also be surveyed for selected species. within the marsh are an intrinsic part of many A key attribute is the vegetation zonation, deter- marshes and also add diversity. Structural diversity mined by tidal submergence. The zonation is within the vegetation may be very important for usually simple to observe and map by using trans- invertebrates. Variation in the salinity of the sedi- ects. Transitions to freshwater swamps at the ments adds to the floristic diversity. 152 5 HABITAT REQUIREMENTS AND ISSUES

Table 5.19. A summary of the quality attributes providing an indication of the condition of saltmarshes, and their recommended monitoring techniques

Attribute Habitat properties Monitoring technique

Physical Extent Phase I mapping (Section 6.1.5) with aerial properties photography (6.1.3) NVC surveys (6.1.6) with quadrat (6.4.2) or belt transect (6.4.6) sampling or fixed-point (6.1.4) photography Saline sediments or water Conductivity meters, soil analysis (6.2.2) Physiography (salt pans, Physical mapping, aerial or fixed-point photographs creeks, etc.) (6.1.3, 6.1.4) Organic litter Physical mapping, aerial or fixed-point photographs (6.1.3, 6.1.4) Composition Characteristic communities Quadrats (6.4.2) or transects (6.4.6), with NVC analysis (6.1.6) where NVC communities are Notified Features or important attributes Species composition and richness Mini-quadrats (6.4.3) Presence–absence of typical or Look–see or total counts (Part III, Sections 15.2.1 and indicator species Section 15.2.2), quadrats (6.4.2 and 6.4.3) or transects (6.4.6) Structure Zonation Transects (6.4.6) Dynamics Accretion on existing marsh Level surveying (not covered) Tidal inundation Observation at peak high tides, water level monitoring

Deposits of organic litter from vegetation are The main threats are erosion and land reclama- typical of the strandline on the upper shore, and tion, which can be monitored from changes in indeed contribute to the nutrient balance of some extent, heavy grazing, which can be monitored upper-shore communities (e.g. SM24 Elytrigia ather- from the vegetation, and pollution. Turf cutting ica saltmarsh). These deposits are of natural occur- may cause damage locally but is generally sustain- rence, but are now often supplemented with much able. Oil pollution is generally damaging to salt- human-generated rubbish and flotsam. A summary marshes, at least in the short term, although some of the attributes providing an indication of the species are surprisingly tolerant. Natural degradation condition of saltmarshes and their recommended of oil is preferable to removal, as it may cause less monitoring methods is given in Table 5.19. damage to the marshes. The implementation of managed retreat for coast protection works may result in Management requirements and external impacts increased areas of upper marsh in the future. In general, management of saltmarshes is restricted to grazing, which can greatly modify the vegetation 5.16.2 Specific issues affecting the survey structure and species richness. Saltmarshes import- and monitoring of habitat ant for plants are probably best left ungrazed or lightly grazed, but those that are of interest for It is recommended that saltmarshes be monitored birds may be grazed more heavily. Heavy grazing at 6 year intervals. Longer-term studies may be tends to result in poor vegetation zonation. A histor- needed to assess loss and gain due to natural ical view of the grazing regime should be taken. changes in the coastline. They can be monitored 5.16 Saltmarsh 153

throughout the season, although if identification Changes in the sea level, coupled with isobatic of some species such as Atriplex and Salicornia is rebound, may cause longer-term changes in salt- required this is best done in August to September. marshes. Local monitoring data may therefore As saltmarsh composition is variable, careful need to be interpreted against these changes, sampling stratification may be required to ensure which will have to be extrapolated from the few that the full range of communities is adequately and sea-level monitoring sites. efficiently covered. If permanent markers are to be As a result of the tidal nature of saltmarshes and used, it should be remembered that relocation can the presence of creeks (which are often deep, be difficult because of mud deposition. For assessing muddy and complex), particular care must be changes in many features of the vegetation, such as taken to observe safety procedures when monitor- species richness and sward height and cover, the ing. Refer to Part I, Box 2.11, for details of the safety techniques outlined in Section 5.4 can be applied. precautions that should be followed. 6 * Methods for surveying habitats

6.1 GENERAL HABITAT SURVEY AND available, which cover both imaging and non- MONITORING METHODS imaging systems. This section covers only imaging systems. The principal differences between these The methods described in Section 6.1 may be systems relate to their: applied to the surveying and monitoring of most habitat types. Section 6.1.1 provides an overview of * modes of data collection (e.g cameras, scanners, remote sensing technology, which includes both radars etc.); satellite-based remote sensing (Section 6.1.2) and * storage media (film or digital); and the aerial photography (Section 6.1.3). Remote sensing, * platforms from which the instrument operates Phase I habitat mapping (Section 6.1.5) and (aircraft or satellite). National Vegetation Classification (NVC) surveys The optimum data source for any project will (Section 6.1.6) are principally survey techniques depend upon the user’s requirements. To assess for mapping and/or quantifying the extent of dif- the suitability of different sources of imagery, the ferent habitats at a variety of scales. This may be general principles that govern their operation are carried out for a number of different purposes: outlined below. * audits of habitat resources; * the production of maps for management plans; and Data collection * general recording of changes in landscapes and All remote sensing systems depend upon differ- habitats, e.g. to document the result of land-use ences in the way in which ground objects interact changes or management practices. with solar radiation. We can tell the difference between one object and another, and also infer Such methods may also be used for basic monitor- something about an object’s properties by the ing of the presence, extent and distribution of habit- way in which it reflects, transmits or radiates this ats. Knowledge of the distribution and extent of radiation across different parts of the electro- habitats and vegetation types is useful for identify- magnetic spectrum. Recording these variations in ing site features and their approximate boundaries, the visible parts of the spectrum can be achieved defining monitoring units, defining homogeneous photographically or electronically; however, varia- strata for stratified random sampling and locating tions at non-visible wavelengths require the use of samples within defined habitats of strata. electronic sensor technology. Photography uses chemical reactions on the sur- 6.1.1 Remote sensing principles face of a light-sensitive film to record energy variations within a scene. Most other remote sensing The term ‘environmental remote sensing’ covers instruments use sensors to detect these energy vari- all means of detecting and measuring environmen- ations, which are then converted to a digital read- tal conditions from a distance. There is a huge ing. Whereas a camera records an instantaneous variety of remote sensing instruments currently image across a whole field of view, most airborne

# RPS Group plc and Scottish Natural Heritage 2005. 6.1 General habitat survey and monitoring methods 155

or satellite-borne scanning systems depend upon of radiation reflected at different spectral wave- the forward motion of the platform to build up an lengths varies for each vegetation type. If the ‘spec- image from a series of scanned lines (these instru- tral signature’ for a particular vegetation type is ments are often called line scanners). As the instru- known, then it is possible to identify all other ment moves over the ground, the sensor readings areas of the image with the same properties. This vary according to the amount of light reflected back is called digital image classification and there is a from the ground and an image is built up line by wide range of statistical pattern recognition techni- line. Through geometrically controlling these read- ques that support this type of digital image analysis. ings it is possible to build up an image of light However, the effectiveness of these techniques variation over a geometric grid. Each grid cell, called always depends upon the extent to which objects a pixel (picture element), has a digital number that can be differentiated on the basis of spectral and corresponds to the amount of light reflected from textural properties. Often it is not possible to distin- the area on the ground covered by the pixel within a guish between different species of plant, for exam- specified part of the light spectrum. These digital ple. Again the user must be aware that it may not be numbers can either be displayed on a computer possible to use remotely sensed imagery to inter- screen or by using a specialised film recorder to pret traditional ecological classification systems produce a photographic image. (e.g. those based on plant types, cover and The size of the pixel determines the spatial abundance). resolution of digital imagery. This is in turn driven by the height of the instrument above the ground Resolution trade-offs and the focal length of its lens system. Satellite- One very important advantage of satellite-borne borne instruments tend to provide digital imagery sensing systems over airborne ones is that they with a spatial resolution greater than 5 m (i.e. provide the opportunity for regular coverage of an objects smaller than 5 m can be distinguished). area at relatively low cost. They are, therefore, Airborne systems have a much higher potential potentially attractive for monitoring purposes. resolution but they tend to provide one-off cover- The resolution and frequency of coverage is set by age. With all remote sensing systems there is the the satellite orbit and the viewing geometry of the trade-off between spatial resolution and fre- instrument (e.g. wide-angled or telephoto). quency of coverage: no system provides high spa- Geostationary satellites (e.g. Meteosat) are pos- tial resolution with frequent coverage, although itioned over the equator at altitudes of around the most recent Earth observation systems such 36 000 km and therefore proceed at the same speed as SPOT 5 do provide coverage of less than 10m as the Earth rotates. They can provide imagery on an resolution over Europe with repeat coverage every hourly basis over very large areas and are ideally three days. suited for use by meteorological agencies for weather forecasting and climate analysis. Typical pixel sizes From data to information are 4 km (i.e. a square of side length 4 km) at the Remotely sensed images can be used to map vege- equator; such imagery is therefore unlikely to be of tation. Visual interpretation of aerial photography any practical value for habitat analysis at a local level. is a long-established procedure whereby the inter- Higher-resolution imagery can be obtained by preter is able to discriminate and outline different bringing the satellite nearer to the ground. vegetation types on the basis of size, shape, tone, However, this requires the satellite to be in a polar texture, context and shadows. It is possible to inter- orbit and although the spatial resolution of the pret all imagery in this way. However, most digital imagery is improved (e.g. pixel size of 1 km) imaging devices have the ability to record reflec- the temporal resolution is reduced (e.g. 12 hours). tance properties across many wavebands. Many of The most common medium-resolution satellite- these contain valuable information, which helps to imaging systems are also meteorological ones, discriminate between vegetation types. The amount such as the NOAA AVHRR, which are commonly 156 6 METHODS FOR SURVEYING HABITATS

used in television weather broadcasts. These med- As introduced above, a key issue with these ium-resolution systems are still too coarse for most different satellite-borne systems is the trade-off land applications. As a consequence, there is a grow- between temporal and spatial resolution (Table ing family of high-resolution Earth-observing satel- 6.1). This has implications for their application in lite systems. These achieve coverage at a resolution habitat monitoring. Generally speaking, systems that can be measured in metres by the use of long such as AVHRR are used for monitoring global focal length lenses, but in so doing reduce temporal vegetation changes on a seasonal basis, whereas coverage still further (i.e. from hours to days). LANDSAT and SPOT imagery is used for national The Landsat series (seven since 1972) is perhaps the land cover surveys such as the DETR Countryside most well established of the ‘Earth-observing satel- Survey 2000. It is likely that the new high-resolution lites’. The existing instrumentationonLandsat7,the systems such as IKONOS will be applicable to site- Enhanced Thematic Mapper (ETM), records in eight level assessments. A major restriction to the practical spectral bands across the visible, near middle and into application of satellite imagery in the UK is the diffi- the thermal infrared. The panchromatic (black and culty of obtaining cloud-free imagery. The opportu- white) band has a pixel size or a spatial resolution of nities for acquiring cloud-free imagery are greater 15 m. All the remaining bands have a pixel size of for satellites with shorter revisit periods. This high- 30 m, except the thermal channel, which has a poorer lights one of the major advantages of aircraft sur- ground resolution of 60 m. The satellite orbits at an veys over satellite methods. Not only can aerial altitude of 705 km and the time between repeat surveys provide data with vastly improved spatial coveragesis16–18days,dependinguponlatitude. resolution, but the operator is also able to restrict A standard scene covers an area of 185 km 170 km flying sorties to those days with clear conditions. (approx. 31 000 km2). The French SPOT satellite series As the technology develops, airborne remote sen- (five since 1986) offers similar capabilities to the sing may become more capable of supplementing Landsat series but provides the added enhancement field survey information on widespread habitats of simultaneous acquisition of stereo pairs of images and landscape features. (600 km 120 km) from the SPOT 5 platform. Stereo Aerial film camera systems are mature technolo- coverage allows for the derivation of height informa- gies that have been used successfully for many tion directly from the imagery by using digital photo- years. Digital camera technology is now also find- grammetric techniques. The elevation accuracy from ing its way into the airborne imaging marketplace. the High Resolution Stereoscopic (HRS) instrument Not only is processing time reduced (because film onSPOT5isquotedas10m. development is no longer necessary) but also, The first of a new generation of commercial, unlike scanning systems, each frame of imagery is high-resolution satellite systems was launched in captured in a single exposure, which facilitates 1999. Through reducing orbital altitude to 680 km geometric restitution. One problem, however, is and increasing the focal length of the camera, that each frame must be downloaded between Space Imaging’s IKONOS satellite is able to provide each acquisition and so ultimately a limit is imagery with ground resolutions of 1 m in pan- reached at which it is not possible to download chromatic mode and 4 m in multi-spectral mode. quickly enough. Even with the fast pace of technol- This spatial resolving power is comparable to that ogy advancement, it is likely to be some time of high-altitude aerial photography. IKONOS has before airborne digital sensors will be able to com- been followed by two other high-resolution pete with conventional film cameras in terms of spaceborne systems: Quickbird (launched 2001) and image quality and efficiency. OrbView (launched 2003). Information on all of these New airborne scanning instruments, such as the systems is available from a number of websites but Compact Airborne Spectrographic Imager (CASI), themostusefulUKsiteatthetimeofwritingisthat also have considerable potential for habitat evalu- hosted by infoterra, formerly the UK National ation. One particular advantage of the CASI system Remote Sensing Centre (www.infoterra-global.com). is that its configuration is programmable and the Table 6.1. Specifications of some current Earth-observing satellite sensors

Cost of digital data Nominal (bas ed on 2000 prices)b Sensor Year of first No. of spectral spatial Revisit Image frame name launch bands resolution (m) period a (km km) £ per scene £ pe r sqc uare km

IKONOS 1999 2.9 days 13 13 3042 18 Pan 11 XS 44 SPOT 1986 26 daysd 60 60 Pan 1 10 800–1700 0.25–0.50 XS 3 20 800–1350 0.25–0.40 LAN DSA T 16–18 days 185 170 e ETM 1999 7 15–60 400 0.01 TM 1982 4 30–60 160–2200 0.005–0.070 MSS 1972 4 80 120–600 0.003–0.020 AVH RR 1979 5 1100 12 h 2400 2400 8 0 negligible KFA — Film — 1000 580 80 1800–2250 0.30–0.35 3000 Ca meraf 2–3 21 21 2 250–3000 5–7

a For polar-orbiting satellites, the exact revisit period will depend on latitude. b Hard-copy imagery will be cheaper than digital data. The lower price ranges relate to older imagery. c These costs are given for comparative purposes only. It may not be possible to buy imagery on a per km2 basis. d The SPOT satellite is actually steerable and thereby can obtain, by request, more frequent coverage. e ‘Quarter scenes’ of LANDSAT imagery may also be purchased. f Costs here are based on scanned photography but it is also possible to purchase prints. 157 158 6 METHODS FOR SURVEYING HABITATS

precise number of spectral bands, their locations Table 6.2 presents some common land cover and and bandwidths can be selected in flight. A spatial landscape features and poses three questions: resolution of between 0.5 m and 10 m can be 1. What is the minimum ground resolution achieved, depending on the flying altitude. required to detect or measure them? LIDAR (a light detection and ranging instrument) 2. What scale of imagery will provide data at this is often flown in combination with the CASI system. resolution? LIDAR is a laser range-finder that measures the time 3. What instrument platform is most commonly of flight of a laser beam from the aircraft to the used to provide this imagery? ground and back. The information provides elevation data, which can be used for vegetation measure- From Table 6.2, it is possible to identify the techni- ment and mapping and is particularly useful for cal solutions most appropriate to particular map- providing textural definition. Other systems, such ping tasks. Some key points are: as synthetic aperture radar (SAR), offer similar spe- * No single type of imagery suits all purposes. cialist facilities. For further information on such * The requirements for detection are less demand- instrumentation refer to a standard remote-sensing ing than those for measurement. textbook (e.g. Lillesand & Kiefer, 1994). * Users wanting to identify or measure several different land cover features from the same imagery Satellite specifications and cost will have to accept that some will be more prone The major commercial sources of satellite data in to errors than others. the UK are the National Remote Sensing Centre * Remotely sensed imagery generally cannot pro- (now Infoterra) and NPA Group (see Box 6.1 for vide information that is directly comparable to contact information). Table 6.1 provides an indica- botanical classifications (e.g. Phase I habitat sur- tion of the relative costs of imagery. Since satellite vey and NVC). data can be expensive (particularly as it is usually One way of ensuring high mapping accuracies necessary to purchase a whole scene even if the would be to use large-scale imagery, but as photo study site is only a fraction of the area), it is worth scale increases, the number of images required to contacting your local university’s geography and or cover any given area increases geometrically. Scale environmental sciences department before pur- and cost are therefore inter-related. chasing data, because they may know of existing ‘Fitness for purpose’ can only be established by images that may be bought at a much lower cost. being very clear about the trade-offs and inter- Again the major centres of remote sensing expert- linkages between the following. ise are readily found on the Internet. Aerial photographs can be obtained from a variety * Purpose: what do you need to know? of sources. If it is necessary to commission a special * Method: what technical options do you have? survey to meet the data requirements, then the costs * Economy: what can you afford? of flying will have to be included. Monitoring will * Error: what types and level of error can you necessitate several repeat surveys over time. tolerate? Generally, there are no cost savings when multiple Sections 6.1.2 and 6.1.3 describe the applications of aerial surveys are done, but time series of satellite satellite-based remote sensing and aerial photogra- data can often be purchased with major discounts. phy in habitat mapping and monitoring.

Applications of remote sensing 6.1.2 Satellite-based remote sensing Satellite or aerial imagery can be used in a wide range of applications, but selecting appropriate Applications of satellite remote sensing solutions from the growing range of technical The early LANDSAT satellites were principally options can be difficult. employed for expansive crop inventory projects. Table 6.2. Data users’ requirements and recommendations

Image recommendations

Smallest scale for:

Data requirement Ground resolution (m) Detection Measurement Platform a

Land cover classification and mapping Forestry Species 0.1 1 : 5 000 1 : 2 500 LAA Isolated trees 0.3 1 : 12 000 to 1 : 6 400 to 1: 9 600 LAA 1: 20 000 Forest strips < 20 m wide 30 1 : 1 500 000 1 : 750 000 SAT Groups of trees(< 0.25 ha) (mainly 1.0 1 : 64 000 to 1 : 32 000 to 1: 64 000 HAA broadleaved/conifers/mixed) 1: 125 000 Mature forest stand 30 1 : 1 500 000 1 : 750 000 SAT (broadleaved/conifers/mixed) Felling 10 1 : 500 000 1 : 250 000 SAT Non-forest Scrub (species) 0.3 1 : 12 000 1 : 6 400 LAA Scrub (stand) 3 1 : 184 000 1 : 92 000 HAA Grasses (species) 0.1 1 : 3 200 1 : 1 600 LAA Grasses (stands) 3 1 : 184 000 1 : 92 000 HAA Peatland 3 1 : 184 000 1 : 92 000 HAA Blanket bog 3 1 : 184 000 1 : 92 000 HAA Non-vegetated surfaces Rocks and cliffs 3 1 : 184 000 1 : 92 000 HAA Dunes 3 1 : 184 000 1 : 92 000 HAA Built-up land 3 1 : 184 000 1 : 92 000 HAA Urban open space (e.g. cemeteries) 3 1 : 184 000 1 : 92 000 HAA Derelict land 3 1 : 184 000 1 : 92 000 HAA Bare soil 0.3 1 : 12 000 1 : 6 400 LAA Extensive bare soil 10 1 : 500 000 1 : 250 000 SAT Transport routes 3 1 : 184 000 1 : 184 000 HAA Water

159 Coastal water/estuaries 10 1 : 500 000 1 : 250 000 SAT Inland open water 3 1 : 184 000 1 : 92 000 HAA 160 Table 6.2. (cont.)

Image recommendations

Smallest scale for:

Data requirement Ground resolution (m) Detection Measurement Platform a

Marsh 3 1 : 184 000 1 : 92 000 HAA Saltmarsh 3 1 : 184 000 1 : 92 000 HAA Canals 5 1 : 310 000 1 : 155 000 HAA Hydrological condition 10 1 : 500 000 1 : 250 000 SAT Interpretative information Habitat mapping Forest edge 30 1 : 1 500 000 1 : 750 000 SAT Forest–agriculture edge 30 1 : 1 500 000 1 : 750 000 SAT Forest–water edge 10 1 : 500 000 1 : 250 000 SAT Forest–abandoned land edge 10 1 : 500 000 1 : 92 000 SAT Fire breaks 3 1 : 184 000 1 : 92 000 HAA Vegetative condition Insect effect 0.3 1 : 12 000 1 : 6 400 LAA Disease 80.0 1 : 3 900 000 1 : 2 100 000 SAT Pollution effect 0.3 1 : 12 000 to 1 : 6 400 to LAA 1 : 20 000 1:9600 Phenological stage 0.3 1 : 12 000 1 : 6 400 LAA Resource parameter measurement Tree dimensions (height, basal area, 0.3 1 : 20 000 1 : 9 600 L–MAA crown diameter) Biomass statistics (annual production, 0.3 1 : 12 000 1 : 6 400 LAA plant density) Animal counts 0.3 1 : 20 000 1 : 9 600 L–MAA Nesting trees 1.0 1 : 40 000 1 : 20 600 MAA

a LAA, low-altitude aircraft (150–3660 m); MAA, medium-altitude aircraft (3660–9150 m); HAA, high-altitude aircraft (9150–19 820 m); SAT, satellite (over 190 km). Source: Adapted from Aldrich (1979). 6.1 General habitat survey and monitoring methods 161

Box 6.1 Contact information for obtaining Fax: 01793 414606 remote sensing data www.english-heritage.org.uk Air Photographs Unit (correct at time of writing) National Assembly for Wales Infoterra Ltd (formerly the National Remote Cathays Park Sensing Centre) Cardiff CF10 3NQ Atlas House, 41 Wembley Road, Leicester, LE3 1UT Tel: 02920 823819 Tel: 0116 2732300 Royal Commission on the Ancient and Fax: 0116 2732400 Historical Monuments of Scotland www.infoterra-global.com John Sinclair House Nigel Press Associates Group 16 Bernard Terrace Crockham Park, Edenbridge, Kent, Edinburgh EH8 9NX TN8 6SR Tel: 0131 662 1456 Tel: 01732 865023 Fax: 0131 662 1499/1477 Fax: 01732 866521 www.rcahms.gov.uk www.npagroup.co.uk Public Records Office of Northern Ireland English Heritage 66 Balmoral Avenue National Monuments Record Belfast BT9 6NY PO Box 569 Tel: 02890 255905 Swindon SN2 2XP Fax: 02890 255999 Tel: 01793 414600 www.proni.nics.gov.uk

This agricultural monitoring role has continued imagery. To improve classification accuracy, both with the later satellites (e.g. the Monitoring summer and winter imagery was used. Geometric Agriculture by Remote Sensing (MARS) project errors were controlled by geometrically correcting run by the Joint Research Centre on behalf the summer images to the Ordnance Survey of EUROSTAT). The higher spatial resolutions National Grid and then resampling the winter (c. 30 m) provided by these later satellites, particu- images to fit. A land-cover classification system larly the Thematic Mapper (TM), have provided the was developed, which was appropriate both to opportunity for pan-European and national land- user requirements and to the ‘fitness for purpose’ cover mapping programmes. of such medium-resolution imagery. However, At the European level, the principal initiative has some of these classes (e.g. bracken) still had stan- been in connection with the development of a co- dard errors of around 33% (Pakeman et al., 2000). ordinated information network on the environment The 1990 Land Cover Map methodology has been (CORINE). As part of this, each EU member state has refined for a new land-cover map of Great Britain been requested to provide a 1 : 100 000 scale land- (LCM2000). The main reporting structure is based on cover map for their national area. Although most the Broad Habitats identified in the UK Biodiversity member states have obtained this through manual Action Plan. The relationships between these Broad interpretation of appropriately scaled hard copy Habitats and the LCM2000 Target Classes and Sub- LANDSAT TM images, the UK was able to take advan- Classes are given in 6T.3a.ble tage of a national mapping initiative, the Land Cover At an individual country level, similar satellite Map of Great Britain (Fuller et al., 1994). image-based land-cover mapping initiatives have The production of the 1990 Land Cover Map of been conducted by MLURI (the Macaulay Land Great Britain was achieved using Landsat TM Use Research Institute) (Wright & Birnie, 1986; 162 6 METHODS FOR SURVEYING HABITATS

Satellite-based remote sensing: summary of key Precision Satellite-based sensors commonly achieve points a resolution of 10–30 m. The most recent generation of satellite sensors have an improved spatial resolution Recommended uses Satellite-based remote sensing of 1–4 m. may be used for measuring Broad Habitat extent, but is Bias The reflectance properties of areas of vegeta- not currently recommended for detailed site monitor- tion can vary from image to image, owing to factors ing because the spatial resolutions are too poor. such as cloud, moisture and season. These variations However, in conjunction with ground surveys and must be considered for successful application of aerial photography, satellite imagery can be a useful automated classification procedures. additional data source. Expertise required An understanding of the com- The method also has some potential for monitoring puter hardware and software for image habitat quality through measurement of vegetation processing and interpretation is essential. change (e.g. heather cover on a moorland) if a change Experience in recognising ecological and land-cover from a ‘desirable’ to a ‘less desirable’ state can be classes is also required. defined in terms of vegetation change that can be monitored with remote sensors. Equipment required Contact information for The potential of the most recent generation of the major UK satellite data re-sellers can be found in high-spatial-resolution satellite sensors has yet to be Box 6.1. To view and interpret remotely sensed data, a fully explored but may be applicable for some site-level computer capable of handling large quantities of assessments. data and with a good quality printer is required. A GIS (see Glossary) such as ArcInfo is also useful for Efficiency Remotely sensed data are generally manipulating and comparing images and adding extra cheaper to obtain than data obtained by field survey, information. although the size of the study area will affect the cost Key methodological points to consider At present, and efficiency. Satellite imagery is available at differ- satellite-based remote sensing does not provide a ent costs, according to the level of pre-processing that reliable method for monitoring changes in the data have undergone. Some corrections will still be semi-natural habitats. necessary in order to remove, for example, geometric Satellite imagery can be used for site mapping but and atmospheric distortions. does not achieve the level of detail obtained from Field survey is still essential for ground truthing and either Phase I surveys or aerial photography. calibration. This will probably be required for each Airborne remote sensors are capable of separate image. producing detail comparable with that of Phase I Habitat Survey. Objectivity Automated habitat classifications may be objective in the sense that classification is carried out Data analysis Calculation of habitat extent is by computer. However, analysis based on spectral achieved with computer software. If data are input into signatures alone does not benefit from additional a GIS, information derived from other sources, such as knowledge of size, shape, context, etc. ground survey, can be included.

Wright & Morris, 1997; G. G. Wright et al., 1997). * mapping the extent and condition of blanket bogs SNH has also demonstrated the value of satellite (Box 6.2); and imagery in several applications: * woodland monitoring under the Earth Observation Network 2000 (Box 6.3). * primary stratification in relation to the choice of sample areas for the National Countryside In many of these applications, satellite imagery Monitoring Scheme (NCMS); was used in combination with both aerial imagery variants deciduous evergreen deciduous evergreen mown/grazed hay/silage Trees Scrub/shrub Grass, semi-improved, reverting Grazing marsh Set-aside with grass or weeds Rough Barley Oats Maize Oilseed rape Peas Field beans Linseed Sugarbeet Potatoes Unknown arable Horticulture Perennial crops Set-aside (bare) Neutral – unimproved/neutral Standing Agricultural/managed grass Felled Wheat woodland Broadleaved and mixed grasslands and bracken LCM2000 Target Class LCM2000 Sub-classes and Coniferous woodland Natural and semi-natural Improved grassland The relationship between terrestrial Broad Habitats and LCM2000 Classes woodland Table 6.3. Broad Habitats Broadleaved, mixed and yew Coniferous woodland Neutral grassland Boundary and linear featuresArable and horticulture (Not identified in LCM2000) Arable and horticulture Improved grassland

163 and variants ) or herbaceous with rushes Molinia Nardus ‘wet’ heath ‘dry’ heath gorse shrub grass ( Open heath Fen/marsh Calcareous Acid Bracken Despoiled Water (inland) Continuous urban residential/ commercial industrial Bog Rock/shingle Dune – with/without shrubs Saltmarsh, grazed and ungrazed Closed heath Natural Swamp Suburban/rural developed Bog Supralittoral rock and sediment Littoral rock and sediment Rock, mud and sand LCM2000 Target Class LCM2000 Sub-classes Inland bare ground Sea/estuary Dwarf shrub heath Montane (bare/heath) ) cont. ( Table 6.3. Broad Habitats Fen, marsh and swampBog Fen, marsh and swamp Calcareous grassland Acid grassland Bracken Dwarf shrub heath Built-up areas and gardens Built-up areas and gardens Standing open water and canals Rivers and streams Montane habitats Inland rock Supralittoral rock Supralittoral sediment Littoral rock Littoral sediment Oceanic seas Sublittoral categories

164 6.1 General habitat survey and monitoring methods 165

and ground data. Such integrated approaches – Aerial photography has been widely used in combining census data with sample data – are ecological applications. It has been used for both increasingly used. So the question is not whether inventory and monitoring at national to local one source of data is better than another, but how levels, especially as an adjunct to Phase I habitat they can best be used together. surveys. Whereas in the 1970s it could be said that the interpretation of aerial photos was a well-devel- 6.1.3 Aerial photography oped area technically, recent developments in the use of digital image acquisition and analysis tech- Recommended uses niques have opened up a whole new range of There is a wide range of potential uses for aerial approaches including the advent of digital camera photography. The relationships between resolving systems, on-screen interpretation and the linkages power and photo scale (Table 6.2) hold true, with GIS technology for analysis and presentation. and aerial photos are generally best employed to There are many examples of national surveys in identify and classify structural components in the the UK that employ aerial photography. Some are landscape. They are not generally suited to species- specifically related to baseline audit, others use based classifications. historical aerial photography to provide either a

Box 6.2 Scottish Blanket Bog Inventory The method employs an unsupervised classification of Landsat 5 Thematic Mapper 30 m imagery, which is The Scottish Blanket Bog Inventory (SBBI) is an validated by National Vegetation Classification (NVC) example of the use of remote sensing for characterising ground survey. The classified image products will extensive biotopes more consistently, repeatably and provide improved information on the vegetation cost-effectively than can be achieved by any other communities and hydrological status of blanket bogs means. Undertaken by Scottish Natural Heritage, the throughout Scotland. SBBI maps the extent, distribution and condition of For further information, see Reid & Quarmby blanket bog vegetation throughout Scotland. (2000).

Box 6.3 Earth Observation for Natura 2000 use of Earth Observation images and techniques for (EON2000) environmental monitoring applications. Although the spatial resolution was found to be Habitat inventory and land-cover change information is insufficient to generate the more detailed inventories required across Europe to support the Natura 2000 required, the potential of basic classification for scheme. Developing a method for routine data collec- baseline inventories at a national level was acknowl- tion over such a wide area presents obvious difficulties. edged. Change detection approaches successfully Designated sites in Scotland, Austria and Finland were flagged up ecological change and the method was selected to test the possibility of using imagery from recognised by conservation organisations as being of space-borne sensors to derive forest habitat inventories. practical application in targeting ground survey Landsat TM, IRS, LISS, SPOT Pan and IRS Pan images resources. Lack of available satellite sensor data to (Table 6.1) were used for the inventories, and historic evaluate ecological change was flagged up as a major Landsat TM images were used to validate and demon- issue for an operational system. strate methods of change detection. An Internet-based For further information see http://geospace.co.at/ system was designed and implemented to facilitate the EON2000.html. 166 6 METHODS FOR SURVEYING HABITATS

Aerial photography: summary of key points when calculating areas with a planimeter or digitising equipment, areas on slopes will be underestimated and Recommended uses areas of high relief will be overestimated relative to * Rapidly assessing the nature conservation resource areas of low relief. in an area Expertise required Mappers should be trained in the * Establishing a framework of data for a monitoring recognition of different habitat types from photo- baseline graphs, and in the use of stereoscopes. The ability to use * Monitoring broad-scale changes in habitat extent a planimeter or digitising equipment is necessary if these items are used to process images. It is helpful if the Efficiency Six days maximum AQE are required to people analysing the photographs have on-the-ground evaluate each 5 km 5 km square (including one day experience of the area involved and either have general field checking). ecological and land-cover experience or have been Objectivity Reasonable as long as standard trained in Phase I habitat surveying (see Section 6.1.5). methods are used for distinguishing between habitat Equipment required Overlapping aerial photographs, types and field checking is used to assess accuracy. stereoscope, digitising equipment, pens, pencils, rulers, A problem arises in areas where few distinctive light table, etc. for map-making. boundaries occur and a line has to be drawn Key methodological points to consider Good-quality between two habitats that grade into each other. overlapping vertical aerial photographs are essential. This problem derives from a fundamental problem of Colour photographs are preferred, if available. For using a map to represent natural variation and will monitoring, two matching sets of photographs are lead to variations between interpretations by different required, taken at the same time of year for the area people. being monitored. The time of year the photographs Precision The errors involved in measuring habitat were taken is important; some habitats are hard to areas on 1 : 10 000 scale maps are generally well below identify at certain times of year. Some field checking 5%, although some habitat types are more prone to will be necessary, particularly for habitats that are hard errors than others. to recognise accurately from photographs. Bias Sources of bias arise from misidentification Data analysis Areas of habitat can be measured via of habitat types from photographs and inaccurate digitisation and analysis with a GIS package such as Arc mapping of boundaries. Unless slopes are included View.

census of land cover change (e.g. Landscape Change * Slow changes in quantity, often associated with in the National Parks; Countryside Commission, minor shifts in boundaries of the order of 1–5 m, 1991) or a sample of change (e.g. the NCMS; over 20–30 years are poorly identified (i.e. they lie Mackey et al., 1998). There is a growing body of within the bounds of line positioning errors). knowledge concerning the use of aerial photogra- * Changes in quality are poorly or seldom identified phy for monitoring change. In general terms, the by using conventional point, line and area inter- following hold true. pretations or mapping conventions. (This type of change is most amenable to the use of digital * Changes can be divided into those relating to imagery.) quantity (i.e. changes in area or stock) and those * Changes in semi-natural communities that involve relating to quality (i.e. changes in composition or complex interdigitating boundaries, which are condition). often transitional rather than discrete, are extre- * Rapid changes in quantity or stock (e.g. major mely difficult to detect and quantify reliably. afforestation in the period from c. 1946 to c. 1988) can be reliably identified by using historical aerial Time series of medium-scale photography (i.e. photography. around 1 : 25 000 scale) can provide the most 6.1 General habitat survey and monitoring methods 167

reliable information on major transfers of stock, (from the period 1940–60). The contact addresses particularly in managed areas such as woodland are given in Box 6.1. Other more recent sources and arable land. They provide least reliable infor- include the company ‘getmapping’ (www.getmap- mation on changes in the quality or composition of ping.co.uk). In addition, airborne scanning systems land cover types or in complex and slow changes (e.g. CASI) can be hired from independent organisa- (e.g. in semi-natural cover types). To maximise the tions. These images can be either digital or analo- potential for detecting changes in these situations, gue and can in some cases achieve a level of detail it is recommended that longer time intervals similar to that obtained with Phase I Habitat between photographs be used. Surveys. A fuller review of this technique is given in Pooley & Jones (1996). A stereoscope provides a three-dimensional Expertise required image from overlapping pairs of photographs. Interpretation of aerial photographs is a skill This facilitates the identification of habitat types, acquired largely through experience. Anyone as the height and texture of vegetation becomes undertaking analysis of aerial photographs should more obvious. There are two sizes of stereoscope be trained to a consistent standard in the recogni- that are useful: a small portable set is easily tion of features on photographs. Previous ground employed for mapping but can only be used on a knowledge of the area can make it easier to recog- small part of a 22 cm 22 cm photograph at a time, nise and interpret features on the photographs whereas a large desktop mirror stereoscope allows (although this might introduce some bias). the viewing of the whole overlapping area. Interpreters will need to be familiar with the For mapping, a set of coloured pens and pencils use of stereoscopes and digitising equipment. If plus drawing equipment is required. Crude area on-screen interpretation and digitising is to be estimates can be obtained by using a Romer dot attempted, interpreters must be confident that grid (a transparent overlay with a given density of they can distinguish the same level of detail from dots per square unit) or a planimeter. However, a the screen as from traditional stereoscopic analy- low-cost digitising tablet will provide more reliable sis. Some additional training may be necessary; measures and will enable maps to be digitised and on-screen stereo-interpretation facilities represent manipulated with a GIS package such as ArcView. a new technology, and experience of best practice is Some field checking is recommended when ana- limited. A comprehensive background to aerial lysing aerial photographs; the equipment required photograph interpretation is provided by Lillesand for this is similar to that required for Phase I habitat &Kiefer(1994). surveys (Section 6.1.5). The design of appropriate field checks may require some statistical advice to Equipment required ensure appropriate methods that avoid biasing the Good-quality aerial photographs are essential results and ensure cost-effectiveness. (Appendix 6). A 60% forward overlap is required to provide stereo coverage for use with a stereoscope. The choice between colour and black-and-white Methods photography will depend on the availability, sea- Selection of photography son of acquisition and quality of photographs, the If the available sources of photographs are inade- habitat type of interest and the preference and quate, commissioning photography may be experience of the individual interpreter. The required. Some operators provide low-cost small- Ordnance Survey (OS) hold and provide records format aerial photographs (e.g. 35 or 70 mm). These for the past 10 years, before passing these on to can be useful, providing the equipment to analyse national organisations. The English Heritage them is available (for example, many older stereo- National Monuments Record office in Swindon plotters are set up to deal only with large-format holds older OS photos, their own, and RAF records photographs). 168 6 METHODS FOR SURVEYING HABITATS

Outline methods estimation of the environmental factors responsible Overlapping matched pairs of aerial photographs for making up the landscape, supplemented by are examined under a stereoscope, and blocks of satellite data (Box 6.4). The classification is hierarch- distinct habitat types are identified. It is possible ical, split initially into linear features (e.g. hedge- to mark outlines and calculate areas directly on rows and tracks) and area features (eg. woodland, the photographs. However, it is generally prefer- scrub). able to transfer habitat boundaries to Ordnance As an example at a country level, the Land Cover Survey base maps (usually 1 : 10 000 scale) by Map of Scotland (carried out by the MLURI) was using an optical device such as a Sketchmaster more ambitious. It was a complete survey of and standard colour codes. This mapping process Scotland and identified many more habitat types allows for the correction of relief distortion and than did the previous surveys (Box 6.5). camera effects. An easily interpretable map that Although most studies have recommended can be stored and copied as required is also pro- that a standardised habitat classification is desir- duced. Alternatively, a planimeter, a photogram- able, they generally have created their own var- metric plotting instrument or a digital iants. Comparisons between surveys are made photogrammetric device can be used to map vege- harder and an agreed standard classification has tation directly from the photographs once the not been formalised across the UK (but see Gilbert boundaries have been identified. &Gibbons(1996) for a comparison of different Field checking is recommended to verify that survey classifications). The introduction of the habitat classifications are accurate. UK Biodiversity Action Plan and its recognition of Broad Habitats (Table 6.3) may stimulate har- Habitat classification and identification monisation of UK habitat classification systems. The NCMS (Mackey et al., 1998) used the land classi- Classifications should be decided upon with the fication developed by the Institute for Terrestrial reasons for the study in mind. The quality of Ecology (ITE) for Cumbria (now CEH), based on an photographs available will also affect the choice

Box 6.4 National Countryside Monitoring sufficient detail. Instead, a stratified random sample Scheme (NCMS) of 5 km 5 km squares (later 2.5 km 2.5 km) was developed, covering 7.5% of Scotland’s land area. The NCMS is a Scotland-wide sample survey of land- Land cover was interpreted in terms of 31 areal cover change. Utilising aerial photography from features and five linear features. For each of the 467 c. 1947, c. 1973 and c. 1988, the NCMS has quantified sample squares, the interpreted features were the magnitude, rate and geographical variation in mapped at a scale of 1 : 10,000. Land-cover maps for change over the second half of the twentieth century. each sample square were digitised and processed on During this period, considerable changes took place in a GIS, and overlay analyses allowed the computa- Scotland’s urban and rural environment, but prior to tion of land-cover change between time the NCMS little could be said about the overall impact periods. Statistical software allowed sample square of human activities on semi-natural habitats. The data to be extrapolated to provide estimates of NCMS provides an objective account of the key extent, change and interchange for a geographical changes and explains the changing relationships region of interest. Standard errors and confidence between land-cover features. intervals provide a measure of the uncertainty in Aerial photography was used as the source for the estimates due to sampling. land-cover interpretation, but it was impracticable For further information see Mackey et al.(1998)or to map the whole of Scotland’s land cover in www.snh org.uk/trends/landcover. 6.1 General habitat survey and monitoring methods 169

Box 6.5 Land Cover of Scotland 1988 (LCS88) SURVEY METHOD Aerial photography specifically for the project This survey, carried out by the MLURI, was a complete involved mainly panchromatic film, with some natural census of Scotland, covering 78 828 km2. The survey colour coverage in the Central Valley. Collection took was intended to be a baseline for future monitoring, place during 1987–9. Land-cover boundaries were for which a new land-cover classification system was identified by interpreters with extensive local knowl- devised in consultation with SNH and Ecological edge before digitisation. The digitisation of the dataset Advisors Unit within the then Scottish Office. and subsequent field checking took place between 1989 and 1993. OBJECTIVES To provide a basic land-cover inventory for the whole SUMMARY of Scotland, enabling studies of land-cover change, and The LCS88 survey is widely regarded as an accurate to digitise the information for input into a GIS. survey. Potential error sources included the referential error resulting from differences between people in CLASSIFICATION their interpretation of land-cover features. In an The habitat and land-use classification system was assessment of this error it was found that interpreta- hierarchical and recognised summary, principal, tion rates depend upon classification level: overall major and main land-cover features and error rates increased with increased detail. At the most sub-categories. From these different levels, 23 sum- detailed level, the error was estimated at around 25%. mary features and 40 original land-cover features were This reflects the issues relating to error and the use of identified. These were increased to 126 ‘single features’ one image source for all features, particularly at low (i.e. land-cover types) by sub-categories created from levels in the classification hierarchy. the original 40. Area statistics were based on these 126 The use of mosaics, while allowing for the recogni- single features and mosaics of these features. tion of more habitat types, means that estimation of The use of mosaics of mixed land-cover features single cover types is difficult. The survey area covered (defined as ‘visible mixtures of two land-cover 78 823 km2, whereas the area covered by single cover features in which the total area of each is below the measurements was 54 817 km2. The remaining minimum mapping unit for separate identification’) 24 006 km2 is tied up in mosaics. For example, the stretched the number of categories to 1327 individual single feature area of heather moorland in Scotland features. Although this increases the level of complexity was estimated as 6882 km2. If the areas of all mosaics of the classification, it allows the description and mea- containing heather moorland as the primary or sec- surement of land-cover combinations that would ondary feature are included, the total reaches otherwise be ignored, such as wooded bogs. 16 922 km2. To estimate the amount of heather present in the mosaic areas requires an assumption about MONITORING the composition of the mosaics (e.g. 60 : 40). This may or A ten-yearly survey with LCS88 data as a baseline was may not be valid. proposed. Two pilot studies have been conducted in Sources: Gilbert & Gibbons (1996) and MLURI the Central Valley and Cairngorm areas. (1993).

of habitat types: colour photographs can allow monochrome photographs. Colour photographs more types to be distinguished than monochrome may be easier to interpret. ones. As an example, the guide to habitat identifica- Mapping tion given in Table 6.4 is based primarily on the The mapping and calculation of areas from aerial study by Langdale-Brown et al.(1980), which used photographs requires the identification of features 170 6 METHODS FOR SURVEYING HABITATS

Table 6.4. Characteristics of habitat types for aerial photograph analysis by means of a stereoscope

Habitat type Characteristics

Deciduous woodland Tallest vegetation with rounded crowns varying in height and diameter with irregularly spaced occasional gaps Light and medium tones Coarse, irregular texture Rounded shadows Light, feathery appearance on winter photographs Coniferous woodland Tall, dense stands, small-crowned trees regularly spaced Medium to dark tones Medium regular texture Pointed conical shadows Mixed woodland Tones vary from light to dark Irregular texture Variously shaped shadows Scrub Predominantly woody vegetation of medium height: shrubs, bushes, occasional trees often interspersed with patches of grassland Some distinct rounded crowns and areas of coalescing canopy Mottled appearance due to mixture of woody vegetation (medium and dark tones) and grasses (light tones) Dwarf shrub heath Low vegetation Very dark tones Fine and regular texture giving a smooth, dark appearance Unimproved grassland No perceptible height Irregular mix of light and medium tones Fine texture, with occasional rougher or tussocky areas Less regular than agricultural land No signs of cultivation Improved grassland No perceptible height Mixture of light and medium tones Finer and more regular texture than unimproved grassland May be signs of improvement such as drainage lines, walls and vehicle tracks No signs of ploughing Wetland Very varied appearance due to the variety of community types occurring Identification can be based upon local knowledge, the relief of the area or the proximity of areas of open water Open water Either very light or very dark tones No texture Agricultural land Low: no perceptible height Textureless: very fine regular texture Signs of cultivation such as plough lines or farm machinery tracks 6.1 General habitat survey and monitoring methods 171

on the photographs that can be pinpointed on the a different location and digitised photographs and base map. Sometimes this is straightforward, other files kept on computer should be backed up. where there are a great number of anthropogenic features, such as roads, buildings and field bound- Sampling aries, which appear on maps and can also be recog- Given that aerial photography offers a synoptic nised on photographs. However, there may be view of large areas, it is mostly used to provide difficulties in areas of semi-natural habitat where census information. However, it can be used to there are few ground references. In such cases, it provide estimates of habitat area in the same way may be necessary to introduce local control, for as ground surveying. One approach is to use strati- example through use of a GPS. The identification fied random sampling, which can improve preci- of several points of known grid reference is also sion and ensure adequate representation of less essential if photographs are to be analysed or digi- common features in the sample (this is sometimes tised directly. also known as ‘area-frame sampling’). The esti- Areas of uniform habitat type can be marked on mates of habitat area obtained by this method the base map with standard colour codes based on have standard error terms that are directly related those used for the Phase I habitat survey (Section to the number of samples taken. 6.1.5). Colours of maximum contrast are used to Two issues arise from the above: the first relates produce an easily interpretable map. If a mixture to how to stratify and the second relates to how to of two habitat types occurs with no uniform indi- determine numbers of samples to obtain estimates vidual blocks (or blocks are too small to map accu- of a desired precision. A good worked example of rately), use alternating lines of the colours for each solutions to these issues is provided by the NCMS. habitat. Make the thickness of the lines propor- This shows how lower-resolution satellite imagery tional to the relative predominance of the habitats. can be used to provide adequate information for Moodie (1991) used alphanumeric codes rather stratification (in this case into upland, lowland, than colours for improved grassland and arable intermediate and urban classes). Alternatively, land in order to draw more attention to areas of stratifications could be provided by the ITE’s (now unimproved semi-natural habitat on the map. CEH) Land Classification System, the Land Cover Map of Great Britain or, indeed, more recent classi- Field checking fications such as SNH’s Natural Heritage Zones. The Problems typically occur when attempting to dis- choice of sampling intensity is often a simple trade- tinguish between grasslands and agricultural land, off between cost and precision. The NCMS sample, and between improved and semi-improved grass- for example, provided coverage of 7.5% of Scotland. land. Areas identified as potentially unimproved The ITE Countryside Survey provides a sample of grassland in which no previous survey has less than 1% of Britain. The result is that area esti- recorded this habitat should be checked from the mates for NCMS are useful at a Scottish and local ground by a surveyor trained in Phase I habitat authority region level, whereas the Countryside surveying. Local knowledge can be especially use- Survey data are useful at a national level but ful at this stage. Some limited field checking should become increasingly uncertain at sub-national or be carried out for all habitats to act as a calibration regional levels. Fitness for purpose is a critical con- for the aerial photograph analysis. sideration when designing sampling schemes and it is always advisable to seek statistical advice in the Data storage and analysis design of such schemes. Data storage Good practice dictates that habitat maps created Calculation of habitat areas from aerial photographs should be stored in light- The advent of digitising tablets has largely proof cabinets to prevent colour fading. To removed the need to rely on manual methods of ensure security, separate copies should be kept in calculating areas from maps. The Romer dot grid, 172 6 METHODS FOR SURVEYING HABITATS

the planimeter and a host of other ingenious meth- interpretation blocks on the basis of a checker- ods have now been supplanted by standard func- board design. This forces the need for correlation tions for measuring map metrics within low-cost around edges and acts as an internal check of GIS or autocad facilities. These include not only consistency. area calculations but also a range of other metrics Conventional methods of change detection such as perimeter length (Wadsworth & Treweek, essentially involve map overlay procedures and 1999). For those interested in fully exploiting the hence the need for attention to detail in terms of potential for deriving metrics from digital maps, accurate geometry and labelling. An alternative reference should be made to the spatial analysis approach is borrowed from digital image proces- program FRAGSTATS, which is specifically sing. In this, time series of aerial photographs are designed for quantifying landscape structure (see, scan-digitised and either co-registered (i.e. digitally for example, Haines-Young & Chopping, 1996). The superimposed) or registered to a common map landscape indices provided by FRAGSTATS include base and then superimposed. The advantage of the following. this method is that it makes no prior assumptions about the structure of the landscape. Changes are * patch (e.g. mean patch size) detected as differences between the images, and * edge (e.g. total edge) the interpreter has to separate these according to * shape (e.g. average shape index: the patch para- whether they are real changes or due to normal meter divided by the perimeter of a square of the seasonal variations. This type of analysis is most same size) extensively used in relation to the analysis of * core area (e.g. sum of core areas of each patch) change from long time series of satellite imagery * landscape diversity (e.g. Shannon diversity index) (e.g. to monitor tropical deforestation processes). * contagion and interspersion indices It has only recently been applied to aerial photography, but it offers major advantages in that it Comparisons between photographs enables changes in quality to be assessed and can The standard methods for change detection aim to deal with changes across gradational boundaries. control errors by close attention to geometric and Research is currently being conducted at the mapping accuracy. So, for example, the NCMS MLURI to develop a knowledge-based change detec- methodology used high-precision stereoplotting tion system (SYMOLAC) that uses this approach equipment to ensure accurate location of bound- combined with advanced artificial intelligence aries at each image date so that when the maps methods. For an in-depth review of methods for were overlaid any changes observed were real change detection, refer to Lunetta & Elvidge (1999). rather than artefacts of the method. For ‘look- Change detection also poses problems in valida- back’ studies conducted by the MLURI (alongside tion. In general, changes are measured from a the development of the LCS88), interpretation present that is known to a past that is not (i.e. errors were controlled by providing analysts with historical interpretation has no equivalent ground the 1988 interpretation and asking them to note truth information). In the absence of historical only actual changes. This approach both reduced ground information with which to validate the opportunity for changes due to line misregis- the interpretation of the historical photography, tration and improved the amount of intelligence the only assumption that can be made is that the being given to the interpreters. In both the NCMS known error rates calculated for the present day and the study of changes in the National Parks apply equally to the historical dataset. It is essential (Countryside Commission, 1991), the repeatability to understand that, even with this assumption, the of the photographic interpretation was tested by error rates attached to the change dataset (i.e. when having some areas examined by two different inter- one interpretation is subtracted from the other) preters. Where many interpreters are involved, may be poorer as the errors may not coincide another device to aid consistency is to allocate spatially and will thus be inherited by the change 6.1 General habitat survey and monitoring methods 173

dataset. An analysis of sampling systems for Photographic records can also provide important change detection accuracy assessment is provided information on management operations and visual in Chapter 15 of Lunetta & Elvidge ( 1999). Where a evidence of changes in some environmental vari- considerable investment is planned in developing a ables, such as degree of flooding. Although not habitat monitoring system based upon interpre- directly related to monitoring, photographs can tation of historical sequences of imagery, careful also be useful for site familiarisation during desk attention should be paid to the topic of accuracy studies and provision of illustrative materials for and the method of validation. reports, etc. They can also be very useful for con- vincing people that change has actually occurred Summary of advantages and disadvantages on a site if the timescale of change has been slow Advantages and hence not very noticeable. The main value of repeated photographs is that they provide a quick * Aerial photography provides a relatively quick visual impression of change through time. assessment of extent of Broad Habitat types. Fixed-point photography from ground stations * It can be used as a monitoring baseline. is applicable to a wide range of habitats, but it * Historical trends can be examined by using past must be recognised that in many more open habi- photographs. tats major changes in the pattern of vegetation * The time taken for analysis compares favourably communities will be more readily assessed by with a ground survey. stereoscopic examination of aerial photographs * Boundaries can generally be more quickly and (Section 6.1.3), provided the ground is not steeply accurately mapped than by a ground survey. sloped. On steep slopes, fixed-point photography canbemoreaccuratethanaerialphotography. Disadvantages Photographs can also be used to record individual quadrats if taken from directly above, and these * Fewer habitat details can be distinguished than can be analysed objectively at a later date if neces- with a Phase I habitat survey. sary. Other alternative/additional methods to con- * If photographs are of poor quality, accurate analy- sider include Phase I mapping (Section 6.1.5)and sis is not possible. NVC surveys (Section 6.1.6). * Some habitats can be hard to distinguish on Fixed-point photography of permanent quadrats photographs, necessitating field checking of is often used for monitoring individual species, results. Interpretation errors increase with the particularly fungi, lichens and bryophytes (see level of detail that is attempted. Part III). * Measured habitat area will be underestimated for slopes unless three co-ordinates are used to digitise maps. Likewise, high-altitude areas will be Time efficiency overestimated relative to low-altitude ones. Photography is a cost-effective method for record- * Unknown bias is introduced if habitat extent ing and monitoring change, being relatively cheap is estimated from incomplete photographic and straightforward to carry out. If the use of ran- coverage. ging poles is necessary for lining up repeat photographs or indicating vegetation height (see below), 6.1.4 Fixed-point photography it will be more efficient to employ two people. The time required to sort, document and store Recommended uses photographs should not be forgotten or underesti- Fixed-point photography is considered to be an mated as this is critical to the success of photo- essential part of many monitoring programmes, graphic monitoring programmes. Interpretation as it provides a relatively simple method of record- of changes is normally by subjective visual assessing broad changes in vegetation and habitat. ment and therefore relatively quick and easy. 174 6 METHODS FOR SURVEYING HABITATS

Fixed-point photography: summary of key points * Medium-speed black and white film can be used. Colour will allow greater precision when distin- Recommended uses guishing features/boundaries. High-quality (i.e. sharp and correctly exposed) photographs * Monitoring broad changes in habitat extent and are required. Avoid very bright days, when type, e.g. through succession and patch dynamics shadows create contrasting images that lack * Photographic records are useful for many purposes detail other than monitoring, e.g. recording management * Standard methods should be used that allow operations and site familiarisation photographs to be repeated with the same camera Efficiency Relatively quick to carry out in the field by configuration at the same position at the same time one person; some additional time required to manage of year photographic records; subjective analysis is quick and * It is useful to include graduated ranging poles in easy photographs as markers against which vegetation Objectivity Normally subjective, although semi- height or water levels can be assessed objective counts or measurements can be obtained * Linkage of photographic recording to other moni- with appropriate set-ups toring projects (especially aerial photography) is Precision Not measurable, as data are usually useful qualitative * It is essential that photographs and details of Bias Not measurable, as data are usually qualitative their location, direction, timing and camera con- Expertise required Only a basic knowledge of photo- figuration, etc. are properly stored so that succes- graphy; other techniques are easily learnt sive photographs can be easily retrieved and Equipment required Basic photographic equipment compared and tripod (cost c. £500) Key methodological points to consider Data analysis Photographs are normally analysed * Little need to anticipate changes that are likely to take subjectively. Analysis is therefore sensitive to indivi- place, especially if comprehensive coverage is attained dual interpretation

Expertise required Using the full procedure detailed below will A basic knowledge of 35 mm single-lens reflex increase the time and hence costs of monitoring, photography is essential. Although photographic and is therefore best restricted to cases where: monitoring is relatively simple, and can probably be carried out effectively by most people if they * quantitative measurements are going to be made follow procedures carefully (as described below or from the photographs for analysis; or in other methodological descriptions), training in * you are working in a habitat or landscape with photographic monitoring is desirable. little in the way of distinctive permanent features If the fixed-angle method described below is to with which to orientate yourself by using previous be used, it is recommended that each step be learnt photographs in the field. and rehearsed thoroughly before embarking on the actual photography at the site. The procedure is Equipment required simple once mastered, but care should be taken to The equipment required (see Appendix 6) for avoid mistakes, especially when taking and regis- fixed-point photographic monitoring requires a tering the first photograph in a programme. capital expenditure of about £500. However, this 6.1 General habitat survey and monitoring methods 175

equipment can be used to monitor many sites and Digital cameras are now available and allow easy most of it is likely to be of use for other purposes. computer storage and manipulation of images. The basic requirement of fixed-point photogra- Many digital cameras can now match the resolu- phy is that the system must enable the precise tion of film. If the technology remains in long-term relocation of the camera position in both the hor- use, digital images are preferable to film. izontal and the vertical plane. There must therefore be provision of a permanent marker, whether Field methods already existing or installed especially for the pur- Number and layout of photographs pose (see Appendix 5 for a discussion of the use of Perhaps the most difficult decisions to make in the permanent markers). The use of a firm tripod that planning of photographic monitoring is the num- prevents camera shake and allows the camera to be ber and location of positions from which photo- fixed at the right angle above the right spot is also graphs are to be taken. Where possible, locations recommended. should be integrated with other monitoring pro- The type of tripod used is particularly important jects and also aim to include representative views if the fixed-angle method (described below) is to be of all the interest features on the site and all used. For this method NCC (1987) recommend the major forms of management of each. The Site use of a Linhof Propan pan and tilt head (Model II). Management Statement or Management Plan This can be used with many tripods, but care must should therefore be consulted, together with any be taken when purchasing to ensure that it is com- available survey information (particularly habitat patible and that any existing pan and tilt head on maps) in order to identify appropriate locations. the tripod is removable. The use of a ball and socket It is often useful to take photographs that show a head between the tripod and the pan head is also range of scales including the subject in relation to recommended to avoid the necessity for levelling its surrounding landscape, the subject itself and the tripod. representative detailed shots of the subject. For long-term monitoring purposes monochrome The number of locations chosen, and the range photographic prints are normally recommended as of photographs taken at each, will clearly depend the best material (NCC, 1987) as the negatives and on the size and complexity of the site, but should prints generally last longer in long-term storage than not be allowed to become unworkable. In some do colour equivalents, particularly if properly pro- cases it may be appropriate to devise a programme cessed for archival storage. If monitoring is also whereby different locations are recorded in differ- used for informing management decisions in the ent years and at different return intervals, depend- short term, colour film can provide more informa- ing on the speed of change anticipated in the tion and better discrimination between habitat feature or attribute (see below). However, it is pre- types. You can always use two film backs or camera ferable to take more photographs than necessary bodies with both monochrome and colour films. If than not to take enough. colour slide film is used, the slides can last for several decades if infrequently projected and stored in cool, dark and dry conditions. Frequency and timing of photographs The speed of the film used is also an important In most habitats and situations vegetation changes factor to consider. Fast films will yield less fine detectable from fixed-point photography are unli- detail than will slow films because of their inherent kely to be noticeable at intervals of less than 5–10 grain size, but allow the use of faster shutter speeds years. However, where sudden changes are and/or smaller apertures to give greater depths of believed to have occurred, e.g. as a result of man- field. However, as the photographs are taken from agement or natural events, such as storms, photo- tripods, slow shutter speeds can often be used satis- graphs should be taken to record changes factorily in suitable conditions. On balance, there- irrespective of the time elapsed since the previous fore, a medium-speed film is the best compromise. monitoring. Some habitats (e.g. sand dunes) are 176 6 METHODS FOR SURVEYING HABITATS

notoriously dynamic and therefore prone to mostly Fixed-angle system gradual but potentially rapid changes. Photographic All the equipment necessary for this system is monitoring of features and their attributes in such described above (see Appendix 6)andshouldbe habitats should therefore be more frequent. The used in strict accordance with the following NCC recommended frequencies for monitoring habitat (1987)procedure. features are summarised in Chapter 5. It is important that the time of year at which A Initial photographs photographs are taken within any particular A1 Locate or install permanent marker (see sequence is consistent. If possible,adateshouldbe Appendix 5), making sure enough information chosen when seasonal vegetation change is relatively is recorded for its relocation. stable so that the effects of annual variations in A2 Set up tripod over the marker; centre with aid weather or vegetation are minimised. Alternatively, of a plumb bob slung from base of centre col- some phenological cue may be used, such as the umn, and adjust its height so that the camera flowering of a key species. Where regular manage- lens will be at a standard height above ground ment is practised (e.g. mowing), photography should level. be consistently before or after such activities. In A3 Using ball and socket head: set pan head to level woodlands, features of tree- and shrub-layer struc- position (red line) on tilt scale; fit pan head to ture are best recorded during the winter. In some tripod, level pan head, clamp ball and socket. habitats, winter and summer records may be useful, Without ball and socket head: set pan head to for example for comparison of high and low water level position (red line) on tilt scale; fit pan head levels. to tripod, level pan head by manipulating tripod. A4 Fix camera to pan head, in horizontal config- Taking initial and repeat photographs uration, positioned so that the back of the base- The simplest method of taking repeat photo- plate aligns with mark scribed across the head. graphs is to relocate the fixed points and use A5 Supporting camera, release the two locking previous photographs as guidance for lining up knobs on the pan head, and move camera until a the shot. This may be adequate for many gen- suitable view is framed. Lock knobs tight. eral purposes, but for systematic monitoring A6 Adjust camera settings and take photographs. two systems for fixed-point photography are NCC (1987) recommend two photographs are recommended by NCC (1987) and are described taken. However, given the relatively low cost of below. The first is the ‘fixed-angle system’ film compared with that of staff time, we (Bignal, 1978) used to monitor Loch Lomond. recommend that bracketed exposures are This is recommended for National Nature taken, i.e. one photograph at the predicted Reserves (NNRs) and other situations in which ideal exposure, one underexposed by one f-stop, intensive observations over a long period of and one overexposed by one f-stop. Digital time are envisaged. The alternative ‘centre pole photography is less expensive than film. system’, devised by M. J. D’Oyly, is less time- A7 Select a feature that appears at the centre of the consuming in the field and is recommended horizontal field of the photograph. Step back at where there are problems with access, topogra- least two paces, and take a compass bearing phy or a shortage of resources. over the lens centre of the camera to the The method chosen to relocate photographs will selected feature. (If there is no suitable feature it depend on the actual use to which they will be put; may be necessary to locate a ranging pole, or there is little point in precisely relocating points by similar marker, in the middle view, but this is using the fixed-angle system if one is using the laborious unless an assistant is available.) photographs to make a simple subjective assess- Record the bearing. ment of broad changes. A8 Record tilt angle from the pan head scale. 6.1 General habitat survey and monitoring methods 177

A9 Make sure that the following have been height, lens used and focal length, any filters recorded: date, time of day, site, location refer- used, film type, exposure details, film roll and ence, compass bearing, tilt angle, camera exposure numbers. Notes on weather condi- height, lens used and focal length, any filters tions and features shown in the view should used, film type, exposure details, film roll and also be recorded. exposure numbers. Notes on weather condi- B9 Before dismantling equipment and moving on, tions and features shown in the view should make sure that all views from the point have also be recorded. been repeated. A10 Before dismantling equipment and moving on, consider whether one or more additional Centre pole system photographs could usefully be taken from the The centre pole system requires the equipment same point (e.g. perhaps as part of a panoramic detailed in Appendix 6 except the pan head and view). Also (although not mentioned in the compass, and was devised to monitor woodland NCC instructions), it is recommended that a cover in an area already covered with permanent photograph of the tripod is taken before it is transects marked by metal stakes at 100 foot removed from the fixed marker. This will help (approximately 30 m) intervals (NCC, 1987). The relocation of the marker on future occasions. method involves photographing forwards and B Repeat photographs backwards along the transect at each stake. This B1 Locate permanent marker (see Appendix 5). generally requires taking a large number of photo- B2 Follow steps A2, A3 and A4 as described above. graphs in a limited time, and the system was B3 Holding compass, step back two paces and, designed with this in mind. This method is perhaps sighting over the lens centre of camera, select best used in areas in which transects or gridlines distant feature that corresponds to the bearing are already marked, unless it is decided to set up recorded for the first photograph. In the permanent markers before photographic monitor- absence of a suitable feature, align assistant ing takes place, which will involve additional time with ranging pole in middle of view or, if single- and expense (see Appendix 5 for advice on setting handed, align ranging pole by taking a back up permanent markers). bearing on the camera. The main feature is a standard ranging pole B4 Align camera so that selected distant feature or placed at a set distance from the camera; the camera ranging pole is central in the horizontal field of is centred on the mid-point of the pole. The proce- view. Clamp horizontal scale of pan head. dures for first and repeat photographs are the same, Remove ranging pole (if used), or move to most and follow guidelines detailed by NCC (1987). appropriate location if required in shot for scaling or estimation of vegetation height. 1. Set up camera at marker, normally in horizontal B5 Set tilt scale to angle recorded for first photo- configuration (although vertical configuration graph. Clamp tilt scale. can be used on steep slopes if necessary), on tri- B6 Check against print of first photograph that the pod. Centre over the marker with the lens a stand- same view is again framed. If there is clearly a ard height from the ground. discrepancy, not explained by the passage of 2. Measure a standard distance along transect time, check, and, if necessary adjust to corres- towards next marker, and plant the ranging pole pond with the original photograph, and record (upright and carefully aligned) at this point. new bearing and tilt angle. 3. Free the ball and socket head, and centre the aim B7 Adjust camera settings and photographs (see A6). of the camera on the mid-point of the ranging B8 As under A9, make sure that the following have pole. been recorded: date, time of day, site, location 4. Clamp the tripod head, adjust camera settings reference, compass bearing, tilt angle, camera and take two photographs. 178 6 METHODS FOR SURVEYING HABITATS

5. From all but the first marker, repeat steps 2–4 Ideally this should be done at a simple level as soon with the camera directed back to the previous as each new set of photographs is taken. marker. In some instances, simple mapping of habitat changes, such as area covered by scrub, may be use- The type of pole and its distance from the camera ful. In turn this can provide quantitative estimates of should be standardised for any particular set of habitat area and change. Mapping is normally done photographs. The pole should also be buried to a by eye, although in some circumstances images can standard depth on each occasion. Alternatively, a be scanned or digitised and areas, etc, calculated by ranging pole support can be used on all occasions computer. Aerial photographs are, however, more so that the tip of the pole rests on the ground and appropriate for such analysis techniques. the pole is held vertically. Box 6.6 outlines the problems that may be encountered with fixed-point photography, and Data storage and analysis some possible solutions. Films should be processed and record sheets and photographs indexed and filed as soon as possible after shots are taken. A good indexing and filing Summary of advantages and disadvantages system is essential. Where possible, the slide index The main advantage of photography for moni- should be computerised and stored in a database toring is that there is little or no scope for or spreadsheet for easy search and retrieval. subjectivity in anticipating the changes that Duplicate sets of photographs should be stored in are likely to take place (NCC, 1987). In any appropriate separate locations. Storage of digital other form of recording there is always the pos- images is simpler. sibilitythatsomecriticallyimportantobserva- Analysis is normally by subjective comparison tion will be omitted from the record simply (by eye) of a series of photographs taken over because of an assumption that change would a period of time, recording any obvious changes. affect particular attributes of the habitat or be

Box 6.6 Likely problems and solutions Difficulties may also arise on mobile habitats. On active dunes, for instance, the natural movement of The most likely problems to be encountered are due to dune ridges can lead to permanent markers being inconsistent camera configurations and inaccurate undercut or buried. Even if the precise horizontal relocations. These can be avoided by carefully location can be found, it may differ considerably in following the prescribed methods and thorough and height. Similar changes can occur on saltmarshes, accurate recording of data. cliffs, and habitats prone to landslides. In such Other problems can be expected to arise from the situations a regular system of photographic recording very changes that are being monitored. Tall herbage or points may be inappropriate and it may be better to use woody growth may develop on or just in front of the carefully selected camera locations that can be camera position. This may lead to a temporary reasonably expected to remain stable. In some interruption in photographic records. If this is likely to circumstances the construction of purpose-built plat- be for a long time (e.g. through tree growth) or is forms for photographic recording may be necessary. unacceptable for other reasons, then it may be appro- Weather conditions can also cause problems. Wet priate to relocate the observation point. This should be and misty conditions should be avoided, and very precisely recorded. Sometimes a degree of ‘gardening’ bright and sunny weather can also be problematic. in the foreground may be justifiable, although in other Shadowing obscures useful detail and can confuse cases it may be unacceptable disturbance to natural interpretation and identification of features and processes. attributes. 6.1 General habitat survey and monitoring methods 179

Phase 1 habitat mapping: summary of key points Expertise required Surveyors must be able to recognise the dominant and other characteristic plant spe- Recommended uses cies necessary for the identification of Phase I survey habitat types. Further botanical expertise is desirable to * Providing relatively rapid records of vegetation and enable extra information to be recorded in the form of wildlife habitat over large areas of countryside target notes * Providing an objective basis for identifying sites Mapping skills are also necessary for surveying in warranting more detailed surveys (e.g. Phase II, the field and for the production of master maps also known as NVC) or deserving consideration for Equipment required No specialist equipment protection required for surveying; basic requirements include * Preparation for planning a monitoring programme, Phase I manual, botanical field guides (see Appendix 3), including identification of features and sampling binoculars and maps. Equipment for producing master area boundaries maps and calculating habitat areas includes basic * Monitoring large-scale changes in the extent and office equipment and Romer dot grids distribution of distinct Broad Habitat types Key methodological points to consider Efficiency Relatively rapid, ranging between c. 1 and * Surveyors must work to a consistent standard to 6km2 per surveyor per day ensure accuracy and compatibility between surveys Objectivity Reasonably objective as long as surveyors * Planning of fieldwork is necessary to ensure that the are adequately trained in surveying and mapping survey area is covered in the field season and habi- techniques tats are visited when key species are readily Precision The errors involved in measuring habitat identifiable areas on 1: 10 ,000 scale maps are generally likely to be * Aerial photographs can be useful to increase the well below 5%, although the original boundaries may speed and efficiency of mapping, particularly in be more variable areas of difficult or restricted access Bias Estimates of habitat area can be biased by * If habitat areas are estimated by using sampling misidentification of vegetation or inaccurate methods, care must be taken to avoid bias arising mapping, especially in fragmented and mosaic from the non-random distribution of habitats habitats. The use of aerial photographs as an adjunct to boundary mapping can help to address this. Small Data analysis Areas of different habitat types are rare habitat types can be over or underestimated if best calculated manually by using a Romer dot grid. areas are calculated from maps by using sampling Maps can also be digitised, analysed and stored in a GIS. techniques. Habitat areas on hillsides will be Areas can be expressed as percentage of a given area underestimated if dot grids are used on covered by each habitat type, or as total area covered by two-dimensional maps. If areas are measured with a each habitat type. Data can be used as a baseline for planimeter or with digitising equipment, altitude can future monitoring, but considerable care must be be included from spot heights to allow some taken in the interpretation of changes because of consideration of slope to be made potential inconsistencies between surveys

in a particular direction. Photographic recording in change that cannot be quantified or tested by the field is also relatively quick and simple in com- objective statistical methods. parison with other monitoring methods and provides an easily interpretable visual picture of 6.1.5 Phase I habitat mapping change with time. The main disadvantage of photographic moni- Anyone carrying out a Phase I habitat survey will toring is that it only gives broad indications of require the Nature Conservancy Council (NCC) 180 6 METHODS FOR SURVEYING HABITATS

publication Handbook for Phase I Habitat Survey: A periods for illustrative and interpretative purposes, Technique for Environmental Audit (NCC, 1990a). It is but are likely to be too insensitive and unreliable beyond the scope of this section to reproduce the for detecting small changes. Phase I mapping may specific habitat classifications and codes necessary be appropriate for distinct habitat types with for Phase I survey, which are contained in the NCC sharply delimited boundaries in which mapping handbook. This section therefore presents a synopsis can be carried out with the aid of aerial photogra- of the manual for general information and reference phy (Section 6.1.3). Under such circumstances, purposes. The reader is referred to the NCC hand- apparent changes in Broad Habitat extent and dis- book itself for specific definitions and procedures. tribution can be treated with reasonable confidence. Recommended uses Phase I habitat surveying is a standardised system Time efficiency developed by the NCC for classifying and mapping Surveyor fieldwork rates will depend on many wildlife habitats in all parts of Britain. Phase I sur- factors, including the relative competence of surveys can provide, relatively rapidly, a record of semi- veyors and the topography, complexity, number of natural vegetation and wildlife habitat over large target notes recorded, and accessibility of the area areas of countryside. Habitat classification is based to be surveyed. The scale of mapping also affects principally on vegetation, augmented by reference survey rates. to topographic and substrate features, particularly Phase I survey rates per surveyor have ranged where vegetation is not the dominant habitat from 0.8 km2 to 6.4 km2 per day. Assuming a total component. of 90 field survey days per year, a total of 81–580 km2 The information provided by a Phase I survey can be covered by an individual surveyor in one field has many uses: it can provide an objective basis season (NCC, 1990a). In practice, the upper end of for determining whether a site merits more this scale is extremely ambitious and should not be detailed Phase II surveys (Section 6.1.6) or whether used for calculating effort required to survey a site. it deserves consideration for protection as an SSSI, As a further approximate guide to the break- Local Nature Reserve, etc. down of mapping stages, the time taken to produce In a monitoring context, an initial Phase I survey and analyse a 5 km 5 km 1 : 10 000 scale habitat is a useful precursor to the design of a new mon- map is: itoring programme for a site. Information from a * Field survey and production of fair copy 8–10 days Phase I map can be used to establish feature and * Production of final copy from fair copy 1.5–2.5 sampling area boundaries and on occasions to iden- days tify strata for stratified sampling, although differ- * Analysis of final copy by using dot grid 1.0–1.5 entiation of vegetation types may be better carried days out by using Phase II (NVC) surveys. A Phase I map can also be used as a clearly defined baseline for Based on Phase I surveys of Cumbria and monitoring changes. However, variations by sur- Lancashire 1983–88 from NCC (1990a). veyors in the identification of habitat types and boundaries are sufficiently high to significantly Expertise required limit the reliability of changes deduced from repeat Surveyors should be competent botanists with an Phase I mapping (see Box 6.10; see also Cherrill & aptitude for accurate field recording and mapping. McClean ( 1999a, b), who found only c. 26% corres- It is essential that surveyors be adequately trained pondence between maps). Therefore, data from to ensure accuracy and consistency both within Phase I mapping are only likely to be suitable for and between surveys. Discrepancies between sur- detecting large-scale changes in Broad Habitat veyors can be reduced if surveyors are trained to a types over relatively long time periods. Such uniform standard. Detailed descriptions of Phase I broad data can be useful when collected over long habitat types, colour codes and alphanumeric 6.1 General habitat survey and monitoring methods 181

symbols are given in the Handbook for Phase I Habitat Each distinct habitat unit is recorded in the field Survey Field Manual (NCC, 1990b). A thorough knowl- by using standard coloured pencils or alternative edge of the major vegetation types and habitats is lettered/alphanumeric codes. Colours and codes necessary, including their dominant and character- should be entered directly on to copies of the istic species. Further botanical skills are desirable: large-scale Ordnance Survey maps. these allow extra information concerning species There are advantages in mapping directly in col- composition to be recorded by using target notes, our in the field, but some surveys have chosen to which draw attention to particular features of use pen or pencil only, mapping habitat bound- interest. aries and using codes to identify habitat types. Surveyors should also be trained in other field- This method is quicker and more convenient, par- work skills, including the use of binoculars in ticularly in wet conditions and when recording vegetation survey, mapping techniques, naviga- uncomplicated areas. The use of colour is prefer- tion and route finding, habitat identification, able in complex areas and where there are large and indications of trophic status, soils and amounts of semi-natural vegetation. Pencil marks land management. Cherrill & McClean (1999a,b) can also be altered at a later date, something that recommend aerial photographs to help improve should be avoided. mapping. It is important to standardise the minimum size The work is physically demanding, so surveyors of habitat unit to be mapped. It is suggested that at should be fit and healthy. 1 : 10 000 scale all habitat units larger than 0.1 ha Writing and numerical skills are required for the should be mapped, and at 1: 25 000 all units larger production of target notes and reports, and the than 0.5 ha should be mapped (NCC, 1990a,b). It is ability to produce neat final maps is essential if possible to map smaller units such as ponds, and cartographers are not employed. target notes can also be used to draw attention to small areas of noteworthy habitat. It is also Equipment required important to agree protocols for mapping fragmen- Appendix 6 summarises the equipment required ted or mosaic habitats. for Phase I habitat surveying. The overall aim of a target note is to give a concise picture of the nature conservation interest of a site Field methods in the context of its land use and management. They Outline method must be clear, succinct and informative; even the Ideally, a trained surveyor will visit every parcel of briefest description can enhance the usefulness of land in the area to be surveyed. The vegetation is the habitat map. Target notes are used to provide mapped on to Ordnance Survey maps, usually at a extra detail in particular habitat types, or to point scale of 1 : 10 000. An area of vegetation is assigned out areas of interest that would otherwise not be to one of some 90 specified habitat types, identified recorded by using the standard habitat codes. They on the map by standard colour codes or symbols. In are very important as they can provide an indication addition, further information is recorded by the of areas that might require further study, as well as use of dominant species codes within many habitat providing useful additional information on any types, and by the use of descriptive ‘target notes’, other features of note identified by the surveyor, which give a brief account of particular areas of such as uncommon or rare plant species, mammal interest. Habitat types and codes are described in signs, bird species, etc. A target note is recorded as a detail by NCC, (1990a,b). Only the standard colours red circle with an individual number on the map; in the Berol Verithin series should be used. These explanations of the reasons for the target notes are are available from stationers or from Berol Ltd, included with the final survey report. Oldmeadow Road, King’s Lynn, Norfolk PE30 4JR. Dominant species in each habitat unit should be Marks made with these pencils, however, do not recorded wherever possible by using standard spe- photocopy or scan into computers well. cies codes given by NCC (1990b). 182 6 METHODS FOR SURVEYING HABITATS

In practice much of the mapping can often be time so that no gaps are left, has much to recom- carried out from public rights of way, with the use mend it. However, some habitats are best surveyed of binoculars at relatively short ranges to identify the at different times of year from others; woodlands vegetation. This avoids the time-consuming process in spring, grasslands in midsummer, heathlands in of seeking access permission, although this will be late summer and autumn and open waters between necessary in areas where no rights of way occur. mid-June and September (see6.9 Box). However, the quality of grazed grassland can be To survey an area one habitat at a time at the very difficult to assess without visiting the actual site. ideal time for each habitat is likely to be costly and Aerial photographs may also be useful as an time-consuming, involving repeated visits to each adjunct to ground surveying. Although aerial area. A suitable compromise would be to survey photography is no substitute for fieldwork when areas most rich in woodland in spring and early carrying out Phase I surveys, the availability of summer, areas most rich in grasslands in midsum- contemporary aerial photographs at a suitable mer, and areas most rich in moorland later in the scale can increase the speed and efficiency with season. Within these areas all habitats should be which field surveys are carried out and the accu- surveyed at the same time. racy of mapping boundaries. Photographs can also The field season should be considered as starting be used to map areas with difficult or restricted in late March – early April in southern and central access or for mapping the interiors of large woods. Britain and late April – early May in the north of Informal or fixed-point photographs may also be Britain. The season generally ends about mid- useful, especially for subsequent interpretation of October, although it may be possible to undertake differences that might simply be the result of sur- some surveying in November if the weather is veyor variation. For large sites a large number of mild. End-of-season surveys should generally be photographs might be required, but this may not restricted to checking previously surveyed areas; be practicable. data from such surveys should be treated with caution because many plant species will no longer be Choice of scale apparent. Phase I surveys are mapped onto either 1 : 10 000 Each day’s fieldwork should be carefully or 1 : 25 000 scale Ordnance Survey maps. planned to ensure that the maximum amount of Generally, countrywide Phase I surveys have ground is covered, and to minimise back-tracking been carried out at either scale, but there has and overlap. Care should be taken to ensure that been an increasing tendency to standardise on a the whole area is covered; a gap may mean that scaleof1:10000despitesomeoftheadvantages another visit will be necessary. of the smaller scale. There is no doubt that, for some uses, a 1 : 10 000 Data storage and analysis scale is desirable as it allows greater detail to The field maps made by surveyors are transferred be recorded, but it is recognised that for very to ‘fair’ maps either by the surveyors themselves or large sites, such as in the Scottish Highlands, a by cartographers. Surveyors are likely to be more 1 : 25 000 scale survey may be the only economic- precise, because they are familiar with the areas ally feasible option. If surveys are carried out at this being surveyed, whereas cartographers will gener- scale it is recommended that full use be made of ally produce more consistent and neater maps. Fair target notes to provide greater detail. maps can be monochrome or colour, but the final objective is to produce an accurate, full-colour Survey preparation master habitat map, which has a high visual impact A work programme should be planned carefully at and is easy to interpret. the beginning of the survey to ensure that the area The procedure for the preparation of master to be surveyed is covered in one field season. A maps has varied from survey to survey; for a sum- systematic approach, completing one map at a mary of different methodologies see NCC, (1990a,b). 6.1 General habitat survey and monitoring methods 183

Master maps should be stored in lightproof cab- Wadsworth & Treweek, 1999). The time required inets to minimise colour fading. Colour copies to digitise both the base map and the habitat should also be kept for security. Habitat maps are overlay will be considerablebut,oncecompleted, most easily reproduced by photocopying, either in data processing and extraction and area calcula- colour or in monochrome. A monochrome copy of tion is very quick and accurate. This also allows the master map allows black and white copies to high-quality colour plots to be made whenever be made as required. Habitat area measurements, needed. completed target notes and general description For monitoring purposes, it is recommended sheets should be stored on paper in grid square that areas of all habitats be measured as described order. Fair maps produced in drawing packages above, preferably with the more accurate and can be stored electronically. sophisticated GIS technology. If only a rough idea of habitat extent is required, estimates of habitat Data analysis abundance can be obtained by using sampling pro- For monitoring purposes, either to establish a base- cedures. Refer to NCC (1990a,b) for further details line or for comparison with a previous baseline of sampling strategies for area estimation. survey, the area covered by each habitat type can Calculated areas should be entered into a spread- be measured from Phase I habitat maps. In order to sheet for graphical and statistical analysis, and for simplify this task, NCC (1990a, b) suggest that the ease of data storage and retrieval. 90 or so Phase I habitat classifications be combined to give 34 categories for measurement. Consistent Summary of advantages and disadvantages use of these groups will allow quick comparisons to Advantages be made between different surveys and will facilitate the compilation of regional and national stati- * Provides relatively rapid record of vegetation and stics on habitat extent. habitat type over large areas of countryside. Measurements of the extent of each of the * The use of standard methods and recording pro- different types of habitat in the area covered by cedures allows easy general comparisons between the survey can be made with a Romer dot grid. different surveys to be made. Planimeters are not sufficiently accurate for the * Habitat maps can provide valuable information measurement of small areas. A dot grid is a transfor planning site monitoring programmes. parent plastic sheet covered in regularly spaced * The level of detail obtained in a Phase I survey is dots at a given density (e.g. 10 per cm2). The grid higher than that obtained by using aerial photo- is placed over the map and the numbers of dots graphy or remote sensing. falling in each habitat type are counted. The area of * The use of descriptive target notes can draw atten- each habitat is calculated from the map scale tion to areas that merit further study and can and dot density. For example, at 1 : 10 000 scale record additional ecological information that with a grid dot density of 10 per cm2, 1 cm = 100 m; might be of interest. 1cm2 =0.01km2; 1 dot = 0.01/10 = 0.001 km2.Soif one habitat type is covered by 125 dots, its area = Disadvantages 125 0.001 = 0.125 km2. The advent of digitising tablets has largely * Requires substantial amount of fieldwork before removed the need to rely on manual methods of maps can be compiled and the data analysed. calculating areas from maps. Dot grids and plani- * Habitat classes are relatively broad, so finer-scale meters have now been supplanted by standard variation will be missed. functions for measuring map metrics within low- * Discrepancies between individual surveyors can cost GIS or autocad facilities. These not only lead to biased area estimates. include area calculations but also provide a range * A problem can arise when trying to accurately of other metrics such as perimeter length (see map boundaries between habitat types where 184 6 METHODS FOR SURVEYING HABITATS

there is a gradual transition between the two. This a feature may be defined as a rich diversity, distinct- can lead to biased area estimates. ive mosaic or zonation of NVC types. Where vegeta- * Errors made on original survey maps cannot be tion features have not been clearly defined in NVC checked without returning to the field. terms or other ways, a subsequent NVC survey may * Areas where access is denied, or where access is be used as a post hoc means of providing a precise problematic, such as large, dense woodlands or definition of features on the basis of a standardised wetland, can be difficult to survey from the technique and classification system. Such surveys ground. may also reveal or highlight previously unrecorded * Overall, the method is too insensitive and unreli- features of interest. able for most site monitoring requirements, but it Where NVC types are not named as whole fea- is particularly useful in EIA studies. tures, they may be important attributes of broader habitat features (see Davies & Yost, 1998). A case study of the use of repeat Phase I habitat Furthermore, the presence of locally determined surveys for monitoring vegetation at three sites is constant species, preferential species (i.e. those presented in Box 6.7. that predominantly occur in one community type) and associated species (i.e. other species that occur 6.1.6 National Vegetation Classification in the NVC type) is also a monitoring requirement (NVC) surveys for some habitat types. Thus, to some extent the NVC is often used as a basis for defining the condi- Recommended uses tion of vegetation. However, great care should be The National Vegetation Classification (NVC), pub- taken in the use of NVC datasets from British Plant lished in British Plant Communities (Rodwell et al., Communities as standards for defining ‘poor’ and 1991 et seq.), is the standard phytosociological clas- ‘good’ examples of vegetation stands. Such data sification method in Britain. It offers a reliable should not be used to normalise management of framework for identifying vegetation types, inter- stands to become ‘perfect matches’ to the NVC com- preting the ecological factors that control them, munity tables, because the maintenance of the local and assessing their importance in a national and variation invariably present is central to the conser- local context. The NVC is also often used to describe vation of biodiversity. The NVC types are idealised a field technique of vegetation survey (also known summary classes, which provide reference points as Phase II survey) derived from the protocol used in for classification of vegetation occurring in the field. the original classification study. Thus although the Where NVC types are site features or attributes NVC was not developed as a monitoring tool, it can that require monitoring, a logical starting point is provide a conceptual framework and practical tools to carry out an NVC survey if this has not been for monitoring vegetation (Rodwell, 1997). As this is recently done. Indeed, the establishment of the a rather complex subject with some potential pit- NVC types present will often be a prerequisite for falls, the uses and misuses of NVC for monitoring setting the correct objectives and limits for a site. are discussed in some depth below. Guidelines for identifying attributes that define Perhaps the most valuable use of the NVC is as a condition (see, for example, SNH, 2000) will differ precursor to the establishment of a monitoring according to NVC type. Where NVC surveys are to programme. NVC surveys can provide inventories be carried out, communities and sub-communities and maps of NVC communities and subcommu- should be identified by using properly replicated nities at a site. First, these may be used as a basis quantitative quadrat-based methods (see below) for the identification and characterisation of site rather than subjective visual assessments, even if features (Rowell, 1993); see Part I, Section 2.1. At its these are done by experts. simplest level, a Notified Feature (i.e. one that is In theory, repeat NVC mapping could be used for listed in the designation citation) may be defined as monitoring both the extent and the composition of an NVC community or subcommunity. Alternatively, habitats (in terms of NVC types present, not species 6.1 General habitat survey and monitoring methods 185

Box 6.7 A case study of the use of Phase I survey therefore relate to the date of aerial photography rather for monitoring vegetation than of the field survey; this difference is important if accurate rates of habitat change are required. The repeat INTRODUCTION survey was based on vertical colour aerial photographs. This study (Dargie, 1992) examined the effectiveness Errors due to tilt were noticed on both maps but of repeat Phase I survey as a monitoring data source comparison of fixed-point and line distances suggested for use at sites requiring information on habitat that these were small. There were discrepancies in habi- change. Three sites previously surveyed using Phase I tat definition between the two surveys. The first survey were selected: Benacre Broad, Suffolk; Skipwith did not separate Salix cinerea scrubandomittedasmall Common, North Yorkshire; and Hannah’s Hill, area of unimproved neutral grassland. More seriously, Northumberland. there was confusion between marsh or marshy grassland and inundation vegetation habitat types in both surveys, METHOD plus differences in the separation of wet and dry heath. The sites were resurveyed by, as far as possible, the However, the maps and interpretation, suggesting same methods that were used in the original site an expansion of woodland and a corresponding decline survey. The two completed habitat maps for each site in heathland, bracken and wetland, were well received were produced at the same scale, and the new map was by local experts, and indicated habitat losses not fully overlaid on top of the old one, with a clear acetate grid appreciated by local managers. of 1 mm squares placed on top of both. For each repeat survey map polygon, the types of (3) Hannah’s Hill, Northumberland first survey habitat beneath were noted, with the Both surveys were carried out without the use of aerial number of 1 mm squares that the habitat occupied. photographs, and major differences were found Each repeat survey habitat type had, at the end, a between them. The repeat survey had a much higher count of 1 mm squares for each of its underlying first density of habitat boundaries, and few of these survey habitat types. These data were converted into coincided with boundaries from the first survey. hectares and entered into a transition matrix, with Overall it was felt that the boundary displacement repeat survey habitat codes entered along the top and represented considerable planimetric error rather the first survey codes in the left-hand column. This than actual changes in habitat extent. matrix presented a concise record of measured change, with row (first survey) and column (second CONCLUSIONS survey) totals giving the quantities of each habitat at Perhaps the most important finding of this study was the two dates of survey. that the use of aerial photographs in conjunction with Phase I surveys considerably increases the RESULTS accuracy of the surveys and the confidence placed in (1) Benacre Broad, Suffolk the results. It is essential that monitoring surveys In addition to some relatively small faults in the repeat should be accurate and perceived to be reliable if mapping, two major errors were identified. First, management decisions are to be based upon their mudflats created by the loss of reed swamp were findings. The accurate mapping of vegetation recorded as brackish lagoons because they had been boundaries is therefore vital. inundated by salt water at the time of the survey. Second, The correct identification of habitat types is also local experts considered that both surveys had mistaken very important, but mistakes in identifying habitat areas of reed swamp for inundation vegetation. types can be more easily corrected than can errors in determining boundaries. (2) Skipwith Common, North Yorkshire If accurate measures of habitat change are required The first survey was made by using field checking to it is essential that precise field methods are used in place Phase I categories on to a boundary map derived conjunction with aerial photography and maps from aerial photographs. The boundaries might derived from good photographic rectification. 186 6 METHODS FOR SURVEYING HABITATS

NVC surveys: summary of key points * Time of year for survey; some communities are best surveyed in appropriate seasons (e.g. woodland in Recommended uses early summer) (see Box 6.9) * Where mapping is to be carried out, follow standard * Baseline descriptions and mapping of vegetation as mapping methods, such as Phase I overlain with a precursor to designing a monitoring programme standard NVC codes * Confirmation of NVC types present when these are * Scale of mapping: for most purposes 1 : 10 000 is features or attributes for which monitoring is probably adequate required * Boundaries of vegetation types and mosaics can be * Interpretation of changes in vegetation difficult to define Efficiency Fairly slow and labour-intensive * Ensure representative quadrats are recorded; Objectivity Reasonably objective provided trained quadrat sizes should be selected by following the surveyors are used, but some subjectivity over bound- NVC guidelines aries of communities and especially subcommunities * Surveyors can cover 5–200 ha per day depending on Precision No data available topography and complexity of vegetation Bias Identification of communities and vegetation * Comparisons of repeated simple NVC mapping may be subject to significant bias from individual cannot provide sufficiently reliable estimates of surveyors changes in extent or distribution of NVC types to be Expertise required Competent botanist with NVC appropriate for most monitoring purposes experience * There are a few vegetation types not covered in the Equipment required Quadrats/tape measures, maps, original classification, though these are relatively floras, NVC guide, ruler, compass, spirit level with rare angle measuring device, coloured pencils Data analysis A high level of statistical analysis on Key methodological points to consider properly replicated and sampled data (e.g. G-tests) is * Is an NVC survey necessary: are there more efficient required to assess change with any degree of means to gather the data you require? confidence at the community level

within a community). Given that some interest fea- detailed techniques such as point quadrats; see tures are defined in terms of the NVC, this will be Section 6.4.5) and will not detect gradual change required in some instances. The extent of a selected before large changes have occurred. Measurement habitat could be measured simply from the NVC of structural changes may show the consequences maps and any changes in area assessed directly. of alterations in management regimes long before However, monitoring data from NVC mapping are the NVC classes change. only likely to be able to detect change at a fairly NVC mapping is also time-consuming (see crude scale (e.g. change of community, large-scale below) and therefore costly. NVC repeat mapping damage) and over a long time period. Furthermore, is therefore not recommended as a general method assessing changes in composition within a commu- for monitoring. If NVC mapping is to be employed nity from NVC mapping data alone is fraught with for other long-term monitoring purposes, it is advi- difficulties. It is at best very crude, and confidence sable to have repeated all or part of the survey at can only be placed in obvious changes at a commu- the time the baseline is set up, to assess repeatabil- nity level after inspection of historical data. The ity and obtain error estimates to see whether the mapping data will not be sufficient for assessing method will give the information required. management impacts such as those arising from Instead of conventional repeat mapping it is fertiliser application, etc. (these require more recommended that NVC communities and 6.1 General habitat survey and monitoring methods 187

subcommunities be monitored by more objective Although such analyses may be based on data and quantitative means, such as those employing from NVC surveys, the classification framework quadrat- or belt-transect-based sampling methods can be used in conjunction with survey techniques (see Sections 6.4.2 and 6.4.6). An initial NVC survey that are not themselves of the NVC type. can play a vital role in designing the optimum sampling strategy and methods for such pro- Time efficiency grammes. In particular, NVC maps can identify The time taken to survey an area depends on the the approximate boundaries of vegetation types. complexity of the site, its accessibility, the scale of Irrespective of whether NVC vegetation types are the survey and the skill of the surveyor. A simple features in their own right, or attributes of fea- ‘walkover’ (better defined as a ‘site appraisal’) sur- tures, NVC boundaries can be used to define sam- vey will be quicker than one supported by quadrat pling areas and sampling strata for stratified data (the latter is always preferable). Quadrats in sampling. The maps can also be used to locate species-poor heathland may take 5 minutes to transects across vegetation boundaries where record, in species-rich hay meadows over 30 min- changes in the extent of vegetation stands need to utes, and large 50 m 50 m woodland quadrats be monitored. Although, as mentioned above, NVC over 60 minutes on top of the time taken to do mapping can be time-consuming, the cost of a one- the site appraisal and lay out the grid. off initial survey may often be offset by savings As a crude guide in average lowland areas, a pair obtained through the reduced sampling require- of experienced surveyors (one mapping and one ments of an optimally designed monitoring quadratting) can map about 25–50 ha in lowland programme. grassland or mire (of low habitat diversity) per day, A potential role for the NVC with respect to excluding travel and access permission time. In the monitoring is its use as an analytical and predictive uplands where there are large tracts of similar low tool (Rodwell, 1997). Each NVC vegetation type diversity vegetation, experienced surveyors may be characterised can be related to particular envir- able to cover 100–150 or even 200–300 ha per day. onmental conditions, including climatic, edaphic Sites that are difficult to see over or are very com- and biotic influences, the combination of which plex (e.g. sand dunes, reedbed–fen complexes, mire favours the development of the vegetation type, mosaics) may take considerably longer, with less and the continuance of which is essential to sustain than 5 ha per day being covered. it. Although available information on NVC commu- Allow about double the survey time for typing nities and subcommunities varies, this provides a up quadrats, drawing neat maps, analysing data valuable predictive capacity. This can illuminate and writing the report if the survey takes up to a spatial contrast between vegetation types and tem- week. The time taken to write up is proportionately poral relationships in successions, regressions or smaller for larger surveys but could still take up to lines of deflected development, where serial pro- half as long again as the actual data collection. cesses are still ongoing or where management or other environmental changes have stimulated Expertise required vegetation change. Despite being incomplete, Surveyors should be competent field botanists, such a predictive framework of spatial and tem- able to identify the majority of species in the poral relations enables the fabric of a site and its field. Vegetative identification of grasses, rushes features to be related to potential conditions. The and sedges may be essential for some commu- NVC can thus help to define objectives, identify nities, such as grasslands and mires, as will know- possible management options and aims and pro- ledge of bryophytes, such as Sphagnum spp. in bogs vide some basis for calculating costs and benefits. and Drepanocladus spp. in flushes. A list of botanical Cooper & Rodwell (1995) outline a preliminary identification guides is given in Appendix 3. attempt at such a process for the English Nature Training in survey and recognition of NVC types Yorkshire Dales Natural Area. is important to ensure consistency, especially if 188 6 METHODS FOR SURVEYING HABITATS

more than one surveyor is being used to survey a to Phase I (Section 6.1.5) can be applied to NVC map- large site. Surveyors do not need to know all the ping, although the detail required means that more NVC communities initially, but they should be time is required as well as a higher level of expertise. familiar with those likely to be encountered in The general procedure for NVC mapping is given the course of the survey. There is no doubt that in Box 6.8. If the site already has Phase I maps, take recognition of vegetation types improves with copies into the field and work from them if no experience and knowledge, but it is also well aerial photographs are available, overlaying NVC known (if unquantified) that different surveyors codes as appropriate and checking vegetation may put boundaries between communities and boundaries as you go. especially subcommunities in different places; In addition to these procedures, it is useful to this limits the accuracy of the method. Although take general photographs of the site and quadrats. general ecologists may be able to map boundaries These can convey an enormous amount of informa- of communities and note some changes (e.g. tion not gleaned from the species listed in a quad- encroachment of scrub into heathland), they may rat. Depending on resources and time available, not have the expertise and experience to assess these may be taken by using fixed-point photog- whether community types are changing at the raphy (see Section 6.1.4). same time. Best times for survey Equipment required The best times to survey particular vegetation types The equipment required is listed in Appendix 6 are shown in Box 6.9. These are usually determined Although photographs are not essential, they can by the time at which the vegetation is best devel- be highly informative and will provide invaluable oped. It is inevitable that some surveys will be supplementary information about typical and aty- carried out outside these times. There is little pical examples of vegetation. It may also be worth point in surveying woodland ground flora commu- taking a trowel and a pH meter to take a brief look nities after July, and most wetland communities at soils (Section 6.2.2), which can also provide infor- are best surveyed in late summer. mation about the vegetation type. For monitoring, try to repeat the survey within two weeks of the original day of recording. Field methods Differences between seasons are most significant There is no formal definition of what ‘an NVC sur- in spring and early summer. vey’ actually comprises or what its standards or methods of quality assurance should be. However, Scale of base maps the following field techniques, derived from the In general, 1 : 10 000 maps will provide the basic protocol used in the research carried out to develop background information. A 1 : 5 000 scale is usually the NVC, have been widely adopted. A series of NVC necessary to monitor extent of habitats on most field guides is currently being prepared by the Joint SSSIs reasonably well. Larger-scale maps (e.g. Nature Conservation Committee (JNCC). 1 : 10 000, 1 : 25 000, 1 : 50 000) are only likely to be Many details of the field survey, such as the scale useful for summarising data at a larger scale on a GIS. of mapping, will have to be decided before going into Smaller-scale maps at 1 : 2500 or even 1 : 1250 the field. As the composition of vegetation is a func- may be more use for detailed work. The main limi- tion of the management, soils and climate, it is useful tations with such maps are that recent digital cov- to be aware of the influence of these factors before erage may not be available, they may lack features going into the field; very useful syntheses of each visible on the ground (making location difficult to major group are given by etRo al.d(19well 91 et seq.) pinpoint), and large pieces of paper are hard to NVC mapping should be seen as a more detailed handle in the field, especially in wet weather. form of survey than the basic NCC Phase I habitat The problems of deciding how small an area to survey (NCC, 1990a, b). Much of the advice relating map are discussed in Box 6.10. 6.1 General habitat survey and monitoring methods 189

Box 6.8 General procedure for NVC mapping fundamental to the quality and accuracy of the survey methodology. They should be identified on site, 1. Start with boundaries and edges of sites, and work or within a day or two before they deteriorate. If inwards if possible, working from known locations samples need to be kept for longer then they should to unknown locations. be pressed and dried or, in the case of bryophytes, 2. By eye, select areas of uniform vegetation for kept in dry paper packets to ensure the specimens mapping and quadrats. Selecting ‘uniform’ areas do not go mouldy. does depend to some extent on experience and 4. At each new unknown vegetation type or distinct knowledge of the site, and is best done by walking variant, record enough quadrats to identify the NVC through the areas rather than by selecting from a type from tables in the field, or to allow identifica- distance. Knowledge of key preferential species is tion in the office. Again, record at least five, and essential for identifying homogeneous stands. preferably ten, quadrats. Record vegetation details, Communities that differ often appear as such on the again noting the most characteristic species in each aerial photographs, so these can be used as a guide vegetation type by using the DAFOR scale. to identifying stands. However, not all communities 5. Cross-reference the location of each quadrat on the or sub-communities will stand out on the aerial map. This will allow the quadrat data to be referred photographs; care should therefore be taken when back to particular stands and/or communities. identifying different stand types. 6. Colour in the areas covered by each vegetation type 3. At each new known vegetation type record a on the map to ensure full coverage, and mark on the quadrat of appropriate scale (see Box 6.11 below) appropriate NVC code (it will usually be more and continue to record until at least five, and pre- efficient to ensure coverage at the time than to ferably ten, quadrats have been recorded from the return later to fill in gaps). The standard Phase I site as a whole, deliberately selecting them to show habitat colours (JNCC, 1993) are often useful for the variation you are recording in that community varied sites, although this is less useful for sites with or sub-community (this will be invaluable for any- many different communities and subcommunities body repeating your work in the future). It may be of the same general type (e.g. blanket bogs). If spe- worth recording more quadrats of any particularly cific colours have been used for particular commu- interesting vegetation types. Ensure that the quad- nities in previous surveys it may help to use the rat is sampled entirely within a stand and that it same ones again. If time is limited, or if mapping does not include elements of the surrounding com- onto aerial photographs, the areas of each vegeta- munities; avoid edges and transitions. Do not forget tion type can be marked off with a fine liner pen and to record details of vegetation height, cover marked with the appropriate NVC code. (including dwarf shrub, bryophyte, lichen and bare 7. Draw firm lines for clear boundaries and dotted ground), aspect and slope with the species list. lines for less certain ones; mark mosaics of Quadrats do not need to be marked or relocatable vegetation as mosaics (see also below). unless so desired. Noting the most characteristic 8. As soon as practicable after the survey (it may be species in each vegetation type by using the DAFOR worth doing this every two days while it is fresh in scale can provide additional information. Correct the mind), draw up neat maps and work out the identification of the plants encountered is identity of unknown vegetation types.

Boundaries of vegetation upland heathland coinciding with the transition In the field there are often sharp changes in NVC of peat to mineral soils). In other cases, there is a type directly related to sharp environmental more gradual change from one NVC community boundaries (e.g. change from blanket bog to toanother(forexample.species-richNardus 190 6 METHODS FOR SURVEYING HABITATS

Box 6.9 The best times for NVC surveying

Woodlands: April–June (some types can be surveyed Aquatics: July–September into October) Swamps and tall herb fens: July–September Scrub: April–October Saltmarshes: August–September Hedges/boundaries: April–October Sand dunes: May–August Heaths and mires: April–October Sea cliffs: May–October Hay meadows: May–June or before they are cut Shingle: May–October Upland grasslands: late May/early June – early/ Ruderals: June-October mid -September

gr asslan ds merging i nto upland heathland).co mpT h areis the se wit h th e co nst aant s in th e ta bles ( causes p roblems f or mapping in the f possibleie ld and short-list f or may be obtained by checking monitoring the extent of habitats whe re thetra index nsi- of species in the back of each volume) tions c an be r ela ted t o man agementand (for take examp into accountle , the less frequent species. a relaxation of g razing may re sult i Alwaysn reversion check the description of the vegetation of Nardus grassland to upland he athland). Otheragainst the text and full table. Full details of how communities may form i ntricate mosa icsto interpret(for the tables are given in each British example, springs o f the alpine p ioneerPlant forma- Communities volume.Mapsoftheknowndis- tions oCaricionf bicoloris-atrofuscaeocc ur in scat-tributions of communities in the NVC volumes are tered clusters i n up la nd h eaths). Somevery problems incomplete and should not be used to judge of deciding on boundaries are discussedwhether i n the NVC type identified is likely to be Box 6.10. correct or not. There are two computer programs available Selection of quadrat size that can be used to help allocate quadrat data to Quadrat sizes should be selected as appropriateNVC communities:for MATCH and TABLEFIT (Box the scale of the vegetation in the field6.12 ). Both(see use the basic NVC table data but differ Appendix 4). For linear or irregular features, slightlyquad- in other measures used to give a diagnosis rats of different shape but equivalent area (e.g.may species be richness). They give a measure of required; some small stands such ‘goodnessas of fit’ against the defined NVC types, bryophyte flushes may need to be sampledand mustin only be used as an aid to identification their entirety. The appropriate quadrat sizesand notas for definitive results. They are also no described in the NVC are shown6.11. in TheBox substitute for expert interpretation. There is little advantage of using these sizes is that the todata choose can between them (Palmer, 1992)andboth be directly related to the NVC. cost about the same. A slight advantage of MATCH is that if data are being handled in VESPAN (see Identifying communities Box 6.12) the quadrats can be exported to MATCH In practice in the field, vegetation types are best singly or in groups. The results given must be named from the tables in British Plant Communities taken as guidance only and must only be used as (Rodwell, 1991 et se.)q rather than fr om the ankeys aid , to identification because odd community which do not always work well and contain placements can be given. For example, vegetation relatively little information. From the quadrats with constant Carex nigra in inland Wales has recorded, establish which species are the constants been assigned to a dune slack community by (those occurring in over 60% of the quadrats), MATCH. 6.1 General habitat survey and monitoring methods 191

Box 6.10 Common problems and solutions Mosaics are often very hard to map in the field; if detailed notes of the vegetation are taken it may be SCALE possible to map them later from a distance (e.g. the It is often difficult to decide what is the smallest area opposite hillside) or from recent aerial photographs. to map; this also partly depends on the objectives of Mosaics may also occur within communities related to the survey and is best judged in the field from the scale the growth forms of different species, e.g. shorter grass of the mapping, the community involved and the between large clumps of Deschampsia cespitosa (Tufted context. Three birch trees in the middle of a bog are Hair-grass). In these cases, if it is difficult to decide probably not worth mapping as an NVC type, but are whether this is really one vegetation type or two worth noting as present. Despite their small size it is forming a mosaic, look for qualitative differences in worth mapping all petrifying springs with active tufa the composition of the vegetation related to the two formation as they are listed in the EC Habitats components. If the Deschampsia simply occurs as Directive and are a habitat of European importance. Deschampsia among the same species as in the shorter One small 1 m 1 m clump of Typha sp. (Bulrush) in grass it is probably one vegetation type; if it is a Phragmites sp. reedbed is not a different vegetation consistently associated with other species it may be type as it occurs at low frequency in such vegetation, best to treat it as two communities. but a 10 m 5 m patch might be worth mapping separately. COMMUNITIES THAT DO NOT FIT THE NVC It is very difficult to describe when a vegetation type BOUNDARIES BETWEEN VEGETATION TYPES is a variant of an NVC community and when it does Deciding on the exact boundary between communities not fit properly. Dealing with communities that do is often difficult. The most practical approaches are to not clearly fit the NVC, which may form up to 5–10% pick out ‘good’ areas, which equate to known or of the vegetation in some surveys, can be approached recognisable vegetation types, and either mark an in two ways. First, allocate them to the nearest-fit NVC approximate boundary between them as a dotted type and say in the report that this has been done. line or mark a transition zone including the problem However, for monitoring purposes, this could lead to vegetation. This may require quite a bit of walking to the exaggeration of change. Second, present the and fro, recording quadrats if needed, until the quadrat data and describe them as communities in differences can be clarified. The variability and errors their own right (e.g. ‘hazel hedges’) or give a associated with different surveyors placing boundaries description relating to two or three NVC types between in different places have not been quantified, but are which the community may lie. Given such a complex likely to be particularly significant in sites with many range of communities, it is possible that some may transitions between similar vegetation types. Such actually be included under different chapters of the variability is a major factor limiting the usefulness of NVC (for example, woodland Cardamine amara (Large repeat NVC mapping for monitoring purposes. If Bittercress) flushes are included under mires rather monitoring of the extent and boundaries of vegetation than woodlands). Very detailed localised sampling may is required, appropriately designed quadrat- or also result in many species becoming ‘constants’ transect-based sampling should be used. locally when they are not constants in the wider national context. Contact the local survey teams such MOSAICS as those from English Nature or Countryside Council The traditional treatment of complex mosaics of for Wales as they could have knowledge of other vegetation is to mark an area as a mosaic and estimate vegetation types that have been recorded in the area what proportion is occupied by each vegetation type. of survey. 192 6 METHODS FOR SURVEYING HABITATS

Box 6.11 Sizes of quadrat for NVC surveys

Woodlands: 50 m 50 m for canopy and shrub layers, 4 m 4 m or 10 m 10 m for ground layer Scrub: 10 m 10 m, exceptionally 50 m 50 m in open patchy scrub Hedges/boundaries: 30 m lengths for canopy, 10 m lengths for ground flora Heaths and mires: 2 m 2 m or 4 4 m, exceptionally 10 m 10 m in very impoverished or grossly structured vegetation Grasslands: 2 m 2mor4m 4 m where large tussocky vegetation is present Aquatics: 2 m 2mor4m 4m Swamps and tall herb fens: 4 m 4 m or 10 m 10 m Saltmarshes: 2 m 2mor4m 4m Sand dunes: 2 m 2mor4m 4m Sea cliffs: 2 m 2mor4m 4m Shingle: 2 m 2mor4m 4m Ruderals: 2 m 2mor4m 4 m where large tussocky vegetation is present

Box 6.12 Computer programs for vegetation Huntingdon PE17 2LS (or under ‘software’ on http:// analysis mwnta.ac.uk/ite), price £80 + VAT. TABLECORN, DECORANA and TWINSPAN, 1996, Details are correct at time of writing. M. O. Hill VESPAN 3 (VEgetation and SPecies ANalysis), 1997, A DOS-based program for analysing vegetation data. A. J. C. Malloch TABLECORN converts data from TABLEFIT into A Windows-based program for handling, presenting DECORANA and TWINSPAN formats. Available from and analysing vegetation data including TWINSPAN Centre for Ecology and Hydrology(CEH), Monks Wood, and DECORANA. Available from Biological Sciences, Abbots Ripton, Huntingdon PE17 2LS (or under ‘soft- University of Lancaster, Lancaster LA1 4YQ, price £100 ware’ on http://mwnta.ac.uk/ite), price £75+ VAT. + VAT; upgrades from previous versions £50 + VAT. FIBS MATCH 2, 1997, A. J. C. Malloch FIBS (Functional Interpretation of Botanical A Windows-based program for comparing vegeta- Surveys) was developed by the Unit of Comparative tion data against the NVC. Available from Biological Plant Ecology for English Nature (see Section 6.4.4). Sciences, University of Lancaster, Lancaster LA1 4YQ, CANOCO (CANOnical Community Ordination), price £100 + VAT; upgrades from previous versions £25 1988, C. J. F. Ter Braak + VAT. A Fortran program for canonical community ordi- TABLEFIT 1.0, 1996, M. O. Hill nation by correlation analysis, principal components A DOS-based program for comparing vegetation analysis (PCA) and redundancy analysis. Available from data against the NVC and the EC CORINE types. Microcomputer Power, 111 Clover Lane, Ithaca, Available from Centre for Ecology and NY 14850, USA. Tel: (607) 272 2188. Hydrology(CEH), Monks Wood, Abbots Ripton, 6.1 General habitat survey and monitoring methods 193

Data storage and analysis can then be analysed with the assistance of MATCH Storage and TABLEFIT programs to allocate an NVC type and Quadrat data can simply be filed for later use (cross- similarity coefficient (see below) to each systematic referenced in report, stating storage location), writ- sampling point on the grid. The overall extent of ten up with the report or held on a computer. The each NVC type on a site may then be estimated as best computer program for handling, presenting a frequency of occurrence from the combined sam- and analysing data in a format compatible with ples, and compared between surveys by appropriate the NVC is VESPAN (Box 6.12) but others are avail- tests (e.g. G-tests or 2 tests). If the grid is permanent, able. Maps can be stored on GIS or in hard-copy the NVC type at each location may also be used for format. spatial analysis of change. Standard multivariate ecological analytical techniques such as TWINSPAN, DECORANA and Changes in NVC types present CANOCO (see Box 6.12) can also be used to analyse A crude analysis of changes in NVC types present at larger quadrat or vegetation datasets if data are particular points can be made by comparing repeat collected appropriately. These are extremely NVC survey maps. However, it is often difficult powerful tools. However, quadrat data derived to be certain whether a change is real or simply from NVC surveys for monitoring purposes are due to a different surveyor. Change from a heath- unlikely to be suitable for such detailed analysis. land to a grassland community is likely to be real, Be aware that TWINSPAN is sensitive to the order but a change from one heathland sub-community in which species are input (Tausch et al., 1995; to the most closely related sub-community is more Dirkse, 1998). likely to be an artefact. The original data may need to be examined with care. Analysis and prediction of change The monitoring of changes in the extent and As described above, the NVC provides a powerful distribution of NVC types should be carried out tool for analysing and predicting change. For by using properly replicated quadrat- or belt- example, the use of MATCH or TABLEFIT similarity transect-based sampling programmes. Replicated coefficients to look at changes in the species com- permanent quadrats may be used, but there are position of communities over time is shown in problems with this approach (see Byrne, 1991; Figure 6.1 (see also Rich et al., 1991, 1992). Robertson, 1999). Individual quadrats can rarely As many of the communities are related, be precisely relocated to allow them to be re- changes from one to another may occur with recorded meaningfully (a 10 cm error in relocating changes in management, soils, natural succession, a2m 2 m quadrat can result in 5% error), and etc. By understanding how the communities relate usually too few are taken to allow for appropriate to one another the direction of change can be replication. Repeated estimates of Domin cover understood and therefore interpreted against the values (see Box 2.3) by different surveyors have field situation. For example, the expected direction been found to show differences of up to five of changes in the MG12a Festuca arundinacea (Tall Domin scale points for the same quadrats (Leach, Fescue) grassland, Lolium–Holcus sub-community 1988). In addition, grazing can markedly alter following changes in three different environmen- vegetation structure without significantly affect- tal factors are shown in Figure 6.2. Such changes ing its composition. may occur over periods ranging from a year to A possible approach may be to obtain Domin decades depending on the strength of the driving cover values from at least five quadrats (see force. Details of many of these relationships are Section 6.4.2) placed in representative areas of mentioned in the NVC volumes (Rodwell,1991 vegetation within an approximate distance from et seq), .but these should only be regarded as indica- each of a number of sampling points on a system- tive and there is no substitute for appropriately atically placed grid. The five sets of quadrat data replicated experiments. 194 6 METHODS FOR SURVEYING HABITATS

0.7 * The NVC classification and survey method can be 0.6 used to describe a site and is often used to identify 0.5 and define features and/or attributes that require 0.4 monitoring. * 0.3 The NVC classification and associated datasets can assist with the definition of objectives and the 0.2 setting of limits for a feature. 0.1 * A baseline NVC mapping survey can be used to 0 1970 1975 1980 1985 1990 1995 identify approximate boundaries of vegetation types as an aid to optimising the design of detailed MG6 MG5 objective and quantitative monitoring MG7 MG1 programmes. * The NVC can be used as an analytical tool for Figure 6.1. Changes in MATCH similarity coefficients investigating changes in vegetation and predict- for a hay meadow following introduction of grazing ing the outcome of management, etc. and fertiliser application in 1975 (hypothetical example). The changes in coefficients show a However, the main disadvantages are that change from a hay meadow community MG5 to a NVC mapping can be time-consuming, it requires grazed pasture community MG6. Coefficients for competent botanists, the boundaries between MG7ryegrassleys(whichcanbederivedfromMG6 communities or even the identity of a commu- by applying more fertiliser and heavy grazing) nity may vary with the surveyor, and it may be and MG1 False Oatgrass (Arrhenatherum elatius) too crude to reveal gradual or subtle vegetation grassland (a rank unmanaged grassland type) are changes (e.g. as a result of management changes). also shown. Therefore, for monitoring purposes:

* The NVC should not be used for normalising vegetation types when setting feature objectives and Summary of advantages and disadvantages limits. The NVC can provide a conceptual framework and * Repeat NVC mapping surveys alone should not practical method for monitoring sites that have be used for monitoring the extent or distribution been selected on the basis of their vegetation com- of vegetation communities; other supporting munities. In particular: information is required.

MG6 Lolium–Cynosurus grassland MG11 Festuca–Agrostis–Potentilla grassland MG12a Festuca arundinacea grassland, Lolium–Holcus sub-community MG12b Festuca arundinacea grassland, Oenanthe sub-community

Nutrients + MG6 grazing

Impeded MG12a drainage Salinity

MG11 MG12b

Figure 6.2. Expected directional changes in an MG12a community following changes in three environmental factors. 6.2 Physical attributes 195

only be found on alkaline soils). For further informa- 6.2 PHYSICAL ATTRIBUTES tion on these and other soil characteristics that may The following sections give a brief overview of the be of interest, such as salinity and redox potential, physical attributes of a site that are most likely to consult Jones & Reynolds (1996). require monitoring, namely hydrology and soils. It should be remembered that soils are biological Both of these attributes can have considerable entities, which include vital communities of soil effects upon plant and animal communities. organisms. The health of these fungus, animal For the purposes of habitat monitoring, it is unli- and plant populations is also an important attri- kely that detailed analyses of hydrology and soils bute of soil condition. Soils are also influenced by will need to be carried out as a regular monitoring the vegetation growing in them as well as by the activity. However, some consideration will usually chemical composition of the underlying substrate. need to be given to these aspects at some point, and For example, the decomposition of heather litter so the key issues involved are summarised. releases acids, which tend to lower the pH of the soil underneath the plants. These inter-relations between physical and biological properties of the 6.2.1 Hydrology soil and other ecosystem components are often complex but should be borne in mind when inter- Although probably the most fundamental aspect preting the results of simple monitoring of phys- of wetlands and particularly bog ecosystems, ical attributes. hydrology is all too often ignored in monitoring programmes or added as an afterthought (Lindsay Fertility & Ross, 1994). One of the main reasons for this A broad indication of fertility can be obtained by is that it is a complex subject. Although dipwells measuring total base cations, which indicates the or piezometers, etc., can be easily installed, the supply of plant macronutrients (e.g. nitrogen, potas- interpretation of results in terms of impacts on sium and phosphorus) available in soil solution. features of conservation interest is often difficult. Fresh soil samples and laboratory analysis are Therefore, although it is strongly recommended required. that appropriate hydrological monitoring be carried out where necessary, a detailed treatment of the Soil pH subject is beyond the scope of this Handbook.Itis The pH is a measure of the acidity or alkalinity of therefore recommended that further specialist a solution. It is measured on a logarithmic scale advice on the subject is obtained from appropriate from 1 to 14: a pH below 7 indicates acidity, a pH experts and organisations such as SEPA, the of 7 indicates a neutral solution (e.g. pure dis- Environment Agency, and specialists within the tilled water) and a pH above 7 indicates alkalinity. UK statutory conservation agencies. A pH reading is a measurement of the activity of hydrogen or hydroxyl ions. Soil pH can be meas- 6.2.2 Soil characteristics ured in two ways (both of which can also be used for measuring the pH of water). The study and classification of soils and soil characteristics is a large subject with a considerable Indicator strips amount of literature devoted to it. However, for Strips of indicator paper that change to a particular the purposes of habitat monitoring, assessments of colour when immersed in a solution of a particular many soil characteristics are unlikely to be required. pH are commercially available. Wide-range paper is It will generally be sufficient to restrict soil analysis available, which covers the whole range pH 1–14, but to nutrient status, pH, structure, texture and moist- this is less accurate than using narrow-range paper. ure content, because these have the greatest effect A small amount of soil is mixed with distilled on vegetation (for example, some plant species will water, and the paper is immersed in the solution 196 6 METHODS FOR SURVEYING HABITATS

for several minutes before the pH is measured. measure the depths of the soil horizons. Soil sam- Indicator paper is cheap and quick, but less precise ples from the different horizons can be taken for than a pH meter. chemical analysis. A less destructive and faster method is to take core samples with an auger,a pH meters hollow cylinder that is twisted into the ground If available, a portable pH meter is the best way and removes a cylindrical soil core. to measure pH in the field. A standard electronic Measuring the depth of peat layers may require pH meter has an electrode, which is inserted into several interlocking rods with the soil corer fixed a solution of one part soil mixed with two parts to the end, because peat layers can be very deep. In distilled water. Some pH meters also have a tem- situations in which the underlying sediments are perature probe, which, when inserted into the very different from the peat, the depth of peat can solution, compensates for differences in the tem- be measured by using radar and seismology. perature of the solution from room temperature However, these techniques are still partly experi- (pH readings are affected by temperature). mental, and are expensive (Lindsay & Ross, 1994). Meters need to be calibrated against solutions of Soil texture is a measure of the size of the known pH; buffer tablets to make up solutions of particles that make up the soil. Soil type is a con- pH 4, 7 and 9 are generally supplied with pH meters. tinuum from clay (particle size < 2 mm) through At least two of these should be used to calibrate the silt (2–50 mm) to sand (50–2000 mm) and gravel meter before any readings are taken. It is also a (> 2000 mm) and is based on the relative propor- good idea to check the calibration at regular inter- tions of different particle sizes in the soil. For vals, because some meters have a tendency to drift most biological purposes, the coarse distinctions after a while. Portable pH meters are accurate to of sand, silt and clay soils will be sufficient, but within 0.01 pH units. Laboratory-based instru- more accurate classifications are available should ments can be accurate to 0.001 pH units. they be required (e.g. the texture scale used by the If soil is being measured in the field, it is possible United States Department of Agriculture; see Jones to take samples directly by hollowing out a small & Reynolds (1996)). hole for the electrode, filling this with Field assessments of soil texture from soil pro- distilled water, and inserting the electrode (with files are likely to be sufficient for most monitoring the temperature electrode inserted close by). purposes. However, if necessary particle size can be Otherwise, samples can be mixed in beakers in the measured by passing dried soil samples through field, or collected for later analysis in a laboratory. If sieves of successively smaller mesh sizes, although the latter course is chosen, soil samples should be this is less accurate for small particles than for sealed in airtight bags or containers to prevent the larger ones. A better method is to separate soil soil from drying out before the pH is measured. particles by sedimentation. A sample of soil is mixed in a clear cylinder filled with water. Soil profile and texture Organic material will float to the top, and the soil Asoilprofileisaverticalcross-sectiondownthrough particle types will settle according to size (larger, the soil, which exposes layers or horizons.Anexam- heavier particles will settle out to the bottom faster ination of the profile and the type of soil horizons than small, light ones). The percentages of each present can provide a valuable general indication of particle type can be measured (Jones & Reynolds, the chemical and physical condition of the soil. For 1996) and can be used to classify the soil texture example, the smell of hydrogen sulphide (rotten according to the FAO classification (FAO, 1977). eggs) or presence of a gleyed horizon (dark grey Soil texture and physical properties obtained mottled with orange-red iron oxide patches) indi- from soil profiles are important attributes of soils cates alternating wet and dry soil conditions. but change slowly. Therefore, although measure- Soil profiles can be examined by digging a verti- ments need to be carried out over long time peri- cal, smooth-faced pit and using a measuring tape to ods, observations are only needed infrequently. 6.3 River morphology and aquatic vegetation composition 197

Soil moisture 6.3 RIVER MORPHOLOGY AND AQUATIC The moisture retention capacity of soil is correl- VEGETATION COMPOSITION ated with its organic matter content and differs between soil types. For ecological purposes, soil As discussed in Sections 5.9 and 5.10, survey and moisture is divided into three types according to monitoring of aquatic habitats is a complex and its availability to plants, as follows. specialised subject. Therefore a detailed treatment of the subject is beyond the scope of this Handbook 1. Free-draining water drains away or evaporates and only brief accounts of survey and monitoring soon after rain but may be available to plants for methods are provided below. It is recommended several days, depending upon the soil type (sandy that further specialist advice on the subject be soils drain much quicker than clays) and the obtained from appropriate experts and organisa- drainage characteristics of the site (an imperme- tions such as the Environment Agency, SEPA, able layer, such as an iron pan, can impede drai- Centre for Ecology and Hydrology and specialists nage and lead to soils becoming waterlogged). within the UK statutory conservation agencies or 2. Plant-available (capillary) water occupies the gaps key staff within consultancies. between soil particles and is of most importance for plants as it remains in the soil for longer than does free-draining water. 6.3.1 River Habitat Survey 3. Plant-unavailable (hygroscopic) water forms a thin film on the surface of soil particles, which cannot Recommended uses be taken up by the root systems of plants. (Most of The River Habitat Survey (RHS) has been developed the water in clay soils is held in plant-unavailable in response to the need for a nationally applicable form, and this is why they are more prone to dry- classification of rivers based on habitat quality. It is ing out during droughts than are silty or loamy a logical development of the River Corridor Survey soils, despite containing higher amounts of water.) (RCS), which is principally a map-based system for surveying 500 m lengths of river (see NRA (1992) The plant-available water content of a soil can be for detailed methods). The RCS provides informa- estimated from the loss of weight of the soil at tion on the location of habitats and plant assem- field capacity (i.e. the state attained after the soil blages within river channels, margins, banks and has been saturated and allowed to drain for about the river corridor. Most information is subjective two days) after being air-dried. Keep soil samples in (except for some basic river channel measurements) airtight plastic bags to prevent any and therefore too prone to inter-surveyor variation evaporation before analysis in the laboratory. to be used for most monitoring purposes. However, Measure the mass of each soil sample, then allow RHS provides a more detailed and objective means it to dry naturally (e.g. spread it on paper for a of recording river habitat characteristics that can be week) before weighing it again. The difference used for broad monitoring purposes. between the two masses is approximately the RHS provides four distinct but related outputs: amount of plant-available water held in the soil. Electronic soil moisture meters are also avail- * a standard field survey method (which can be used, able for taking measurements directly in the field. where appropriate, as a consistent framework for collecting data for general monitoring purposes); * a computer database, containing information Soil organic matter from a national reference network of UK sites; A determination of soil organic matter content can * predictions of which physical features are indicate overall biological activity in a soil and the expected to be present within an RHS site at a speed of turnover of nutrients. It is readily meas- particular location (taking into account altitude, ured by igniting dried samples in a laboratory and height of source, etc.); measuring mass loss after burning. * a scheme for assessing habitat quality. 198 6 METHODS FOR SURVEYING HABITATS

River Habitat Survey: summary of key points 2–3 days and no expertise is required beyond a biological background and familiarity with river Recommended uses habitats Equipment required Standard recording forms, maps * To survey the general physical and vegetation struc- and a ranging pole ture of a river Key methodological points to consider * To monitor broad changes in river structure and vegetation, e.g. as a result of pollution or river engi- * Fieldwork is the basis of assessments, supplemented neering works or other impacts with information from maps * The procedure is carried out on 500 m reaches, with Efficiency Relatively rapid: average time for surveying 10 spot checks carried out within each standard 500 m lengths of river is c. 60 min * The survey methods have been developed for Objectivity Semi-objective through standardised rivers in England and Wales but have now been forms expanded for Scotland and Northern Ireland as Precision Tests have shown that inter-surveyor well variation is low and consistent results are achieved irre- * More detailed quantitative analysis of channels and spective of position of spot checks within 500 m reaches vegetation may be required for specific monitoring Bias Subjective assessments are prone to individual requirements interpretation, but this is minimised by training and a detailed methods manual Data analysis The data are amenable for rapid transfer Expertise required Must be carried out by an to the RHS database and analysis by RHS programs or accredited and trained surveyor. Training takes only SERCON (see Section 5.10.1).

RHS aims to predict, with statistical probability, based surveys for bankside vegetation or shallow those features that ought to occur in unmodified rivers and grapnel samples (Section 6.3.2) for examples for the full range of river types in deeper, slow-moving water. England and Wales (although the system has been extended to Scotland). The scheme for assessing Time efficiency habitat quality comprises a simple five-band classi- The technique is relatively simple and quick. fication (excellent, good, fair, poor, bad) based on a According to Raven et al. (1997)thetimetakento comparison of the observed features with those survey a 500 m length of river (i.e. the standard expected for the particular river type. Crude mon- survey unit) varies according to the complexity of itoring can therefore be carried out by reference to the site and ease of access, i.e. inherent factors these broad scales, or in relation to specific targets that affect any river surveying. Simple sites may set for attributes that are measured as part of take only 35–40 min to complete, whereas those of the RHS. complex character may take an hour or more. The Other alternative and additional methods to averagetimeforasiteintheirstudywasjust consider for morphological features include aerial under 1 h. photography (Section 6.1.3), fixed-point photography (Section 6.1.4) or adaptations of quadrat Expertise required (Sections 6.4.2 and 6.4.3) or transect (Section 6.4.6) TheRHSsurveymustbecarriedoutbyan techniques. If quantitative assessments of plant accredited surveyor. However, the training for abundance are required, detailed objective meth- this is relatively simple (2–3 days) and does not ods should be used, such as transect- or quadrat- require specialist knowledge beyond a biological 6.3 River morphology and aquatic vegetation composition 199

background and familiarity with rivers. Although specialist geomorphological or botanical exper- 6.3.2 Grapnel surveys of aquatic tise is not needed, consistent recognition of fea- macrophytes tures included on the field survey form is Recommended uses essential. The technique has been developed by George Hinton at English Nature for the semi-quantitative assess- Equipment required ment of species presence–absence. It is a simple but No specialist equipment is required other than fairly time-consuming technique for establishing the standard field equipment, maps and the RHS frequency of occurrence of individual species, which manual and standard recording forms. can probably be used on lakes of up to 100 ha or Adaptation of standard recording forms on to slow-flowing deep rivers. portable data logging devices is possible and may The data collected can provide an accurate semi- be cost-effective for large monitoring projects. quantitative assessment of abundance and distribution for most species, although it tends to miss Field methods some low-growing plants such as Fontinalis and rosette-forming species. The dominant species (in An illustrated manual (Environment Agency, 2003) biomass terms) is consistently identified and the has been produced and should be consulted for full method picks up species contributing as little as details on field procedures. 5% of the total biomass. Data storage and analysis Other alternative or additional methods to consider include the use of double-headed rakes Data are recorded on standard recording forms or grab samples (see Bell, 1996). Rakes may be and can easily be transferred to the RHS computer used from the shore by throwing out on a line. database, either manually or by optical reading. Grabs are also less prone to bias against small Data analysis programmes are included as part of species, which are not detectable by grapnels. the system, for example for assessment of overall However, these methods collect too much mate- habitat quality. Data may also be used for SERCON rial to be used effectively for anything other than evaluations (see Section 5.10.1). Alternatively, spe- establishing presence. Rake methods may there- cific attributes can be analysed separately. fore be best if boat access is difficult, if the species to be sampled is very rare or localised, or if it is Summary of advantages and disadvantages only necessary to establish that a species is The method provides an up-to-date, tried and present. tested standard means of recording the general Subaqua equipment or ROVs may be used for physical and vegetation character of river reaches, carrying out transects or surveying quadrats etc., which is part of a national surveying scheme. It is but these methods are very slow, expensive and also relatively quick and simple. Although not require specialist equipment and expertise. designed specifically for monitoring, it can be used for monitoring the overall quality of river habitats by a simple five-point scale. The survey Time efficiency methods can also be used as a framework for col- Grapnel surveys are fairly slow to carry out, lecting data for general monitoring of specific but can produce detailed assessments of the fre- attributes. quency of occurrence and distribution of species. However, the technique is largely qualitative Approximately 25 stations across four or five trans- and only semi-objective. It may therefore also be ects can be sampled in a day. A small water body necessary to develop site-specific quantitative and requires at least ten transects of 25 stations and objective monitoring methods for some key attri- therefore such a water body would take at least butes (see Section 5.10.1). two days to survey. 200 6 METHODS FOR SURVEYING HABITATS

Grapnel surveys: summary of key points Equipment required Grapnel and graduated cord and a boat and compass or preferably a GPS for large water Recommended uses bodies; safety equipment; standard recording equipment * Semi-quantitative assessments of the abundance Key methodological points to consider (frequency) of aquatic macrophytes in lakes or large slow-moving rivers * The technique uses a grapnel on a graduated cord to * Mapping the distribution of species and aquatic take small samples of vegetation from the bottom of macrophyte communities the water body; this is repeated 10 times at each Efficiency Relatively slow, but can provide detailed sample location to obtain a frequency estimate of results presence Objectivity Objective * By sampling at many locations a semi-quantitative Precision Moderate map of distribution and abundance can be Bias Biased against small-leaved species developed Expertise required Competence in identifying aquatic vegetation from fragments of vegetation. Data analysis Standard data techniques for the Boat handling and GPS experience necessary in many analysis of presence–absence frequency data can situations be used

However, in larger water bodies, most aquatic A presence of 1 is recorded for each species vegetation will occur in a relatively narrow zone, detected, regardless of its apparent abundance. with little or no vegetation growing where the The method thus provides a frequency of 0–10 for water is deepest. Samples can therefore be targeted each species at each sampling point. in this zone, and this will increase the efficiency of Repeat transects at Bosherston Lakes (Hinton, the method. 1989) showed that the mean frequency values for each species from 250 grapnel drops was within Expertise required 10% of the grand mean (based on 2000 drops). It is essential that surveyors be able to identify aqua- At each sample point the depth is recorded by tic plants from fragments of vegetation. However, as using graduations on the grapnel cord. It is recom- the range of aquatic macrophytes is fairly limited, mended that basic chemical parameters should especially within geographical regions and certain also be recorded at the mid-point of each transect. types of water body, such techniques can be fairly Turbidity should be measured by using Secchi discs rapidly learnt. (Section 5.9.1) and supplemented if possible by in For all but the smallest lakes, samples will need to situ pH and conductivity readings (see Jones & be obtained by boat. Boat-handling experience is Reynolds, 1996). therefore an essential requirement for the surveyor For small lakes the position of each sample point or an assistant. Experience with the use of GPS is also can be ascertained by compass bearings on fixed necessary for surveying large water bodies. points such as church towers, jetties, etc. However, this can be time-consuming and inaccurate on Equipment required large lakes. In these circumstances the use of a The equipment required is listed in Appendix 6. GPS may be appropriate. Recent work reported by Hinton (1997) found that a hand-held GPS is able to Field methods provide position fixing accurate to within 25 m. Ten samples are obtained at each sampling station, During fieldwork the GPS can be used to navigate with the use of a small 7 cm grapnel on a cord. to the selected stations (identified by ten-figure 6.4 Ground and shrub vegetation 201

grid references) at which the boat is anchored distribution targets. It is, however, time-consuming while grab samples are carried out. and tends to underestimate the presence of certain Grapnel surveys should be carried out during species. It can only be used in still or slow-flowing the period from June to September, but the precise water. timing will depend on the species; some species may require surveying earlier in the year. Repeat surveys should be at similar times of the year, 6.4 GROUND AND SHRUB VEGETATION unless seasonal variation is being investigated, 6.4.1 Total counts of individuals and repeated at least every three years. Some rarer species may require monitoring more fre- Recommended uses quently. Initial surveys may have to be more fre- This method is appropriate for monitoring the quent to establish how much variation occurs, both presence or abundance of rare and/or distinct seasonally and annually, and to determine the opti- species that are attributes of habitat quality. The mum monitoring time. target species are normally chosen because of Working from boats can be hazardous; suitable their rarity value in order to maintain a close safety clothing should be worn. Surveyors should check on population levels and to avoid situations also be aware of the risk of catching Weil’s disease. in which a species may disappear from a site Toxic blue-green algae may also be a hazard. through inappropriate management. These can Consult a relevant health and safety policy (e.g. include species that are typical of a particular Part I, Box 2.11) for further information. community or habitat, or other ‘indicator’ species Care should be taken to clean fragments of vege- expected to respond quickly to changes in the habi- tation from the grapnel when moving from site to tat. It may also be an appropriate method to be site; some aggressive introductions can grow from applied to invasive weedy species such as creep- fragments. ing thistle, in situations in which information is needed on the degree of the potential conservation Data storage and analysis problem, again in response to management of the The data can be used to calculate overall mean area. frequency tables for each species over the lake. For some situations, counts of the total number In addition, geographically referenced species fre- of individuals may be more appropriate than the quency data can be stored on a spreadsheet or total area covered. An additional application of this database and displayed over a scanned 1 : 10 000 method is in the assessment of condition, which map by using a standard GIS such as ArcView may be indicated by a minimum population of a (Hinton,1997). particular species, or even a semi-quantitative It should be remembered, when using such threshold. For example, good condition may be analyses to identify trends in abundance, that defined as a particular species being dominant or some aquatic plants are annuals, and populations merely present. will fluctuate from year to year as sites are colo- Where precise estimation of population num- nised and recolonised. Many species fluctuate con- bers is difficult, especially if distribution is highly siderably, both seasonally and annually. Five-year dispersed, then quadrat- or transect-based means of frequency may be used to remove some of sampling methods should be considered (see this natural variation from the data. Sections 6.4.2–6.4.5). However, total counts of individual plants are most often associated with Summary of advantages and disadvantages the monitoring of particular species of conserva- The technique provides a simple method for tion importance. This method is therefore treated obtaining semi-quantitative estimates of species in more detail in Part III under the look–see presence– absence. Data can therefore be readily method (Section 15.2.1) and total counts used for monitoring overall abundance and (Section 15.2.2). 202 6 METHODS FOR SURVEYING HABITATS

Total counts of individuals: summary of key Precision Not relevant to a single measurement points Bias Bias occurs at high abundance Expertise required Dependent on the difficulty of Recommended uses Accurate and absolute population species identification, but characteristic features counts of the changes in number of rare and/or can be quickly learned if only a few species are being distinct: monitored, even if all growth stages are to be recorded Equipment required Basic recording equipment i.e. * ‘typical’ species of a habitat field notebooks, standardised recording forms, * ‘indicator’ species of the effect of management identification notes/guides and hand-held computers changes on the habitat, on occasions * ‘indicator’ species of the health of the habitat, Key methodological points to consider including invasive species e.g. Ragwort (Senecio jacobaea) and Creeping Thistle (Cirsium arvense) * Select species that are suited to this method; it is not Efficiency Relatively quick if the area is small and the appropriate for large and complicated sites species are large and/or obvious; extremely laborious * Search site or area systematically without damage to and time-consuming if the site is large, the species vegetation small, or the vegetation diverse * Consider other methods for estimating populations Objectivity Objective, but subjective variations do for large sites and for populations that may be large exist (see below) or widely distributed

6.4.2 Conventional frame quadrats: cover fewer quadrats have to be recorded to detect the and density estimates same level of change. Thus, changes in values (e.g. of species abundance) are more likely to be Recommended uses real than if a new set of quadrats is selected each Visual estimation of plant cover and abundance (or time. Although measurement error can still occur the presence–absence of species) is a common (for example, through the incorrect identification method of describing vegetation, which can be of species), permanent quadrats reduce sampling applied to the whole study area or to sample plots. variation from data and provide a clear illustration There are several different approaches to the sub- of change at a particular point. ject, but most involve the placing of convent- There are, however, a number of disadvantages ional quadrats (i.e. not mini-quadrats as described of permanent quadrats. Repeated recording con- in Section 6.4.3, nested quadrats as described in centrated in the same small area may itself cause Section 6.4.4, or point quadrats as described in changes in the vegetation through trampling or Section 6.4.5) and/or transects (see Section 6.4.6). continued removal of material for identification. Quadrats may be permanent or temporary. It is also possible that quadrats may ‘naturally’ Permanent quadrats have fixed positions, which become unrepresentative of the area as a whole are relocated at each recording period. Temporary during the course of a monitoring scheme, and quadrats are placed in the area to be monitored but this may significantly bias results if only a few removed after recording is done; a new set of tem- are placed. (This can be overcome by recording porary quadrats is placed in the same area at the sets A and B in year 1, B and C in year 2, C and D next recording period. in year 3, etc.; see Greig-Smith, 1983.) Finally, mark- The major advantages of permanent quadrats ing and relocating quadrats can be very time- are that there is usually less variation due to consuming, although recent developments with the effects of sampling in the change data, and laser range-finders (Total Stations) are making 6.4 Ground and shrub vegetation 203

Frame quadrats: summary of key points recording forms, identification notes/guides and hand-held computer on occasions Recommended uses Monitoring of vegetation when Key methodological points to consider estimates of cover or density are required (e.g. for NVC * Surveyors should familiarise themselves with site surveys) and vegetation prior to survey Efficiency Relatively time-consuming; larger * Optimum quadrat size should be estimated and the quadrats are difficult to search thoroughly; efficiency number of quadrats required calculated from preli- of cover estimates can be particularly poor when minary survey data physical fatigue sets in * Care must be taken when choosing whether to Objectivity Cover values can be very subjective estimate cover by percentages or cover bands (e.g. Precision Deriving cover values can be very the Domin scale) imprecise, especially with large quadrats and * Precision and accuracy of estimates can be increased inexperienced surveyors by subdividing quadrats Bias More conspicuous species, such as those in * Trampling of vegetation may affect the ease with flower or those forming clumps, may be given which species can be seen or cover values overestimated cover values estimated Expertise required Considerable expertise is required to enable the accurate identification of vegetative vascular and lower plants; some (easily learnt) skills Data analysis Standard methods can be applied required for improving estimates of cover values providing that the sample is representative of the site Equipment required Quadrats; basic recording Only non-parametric tests can be applied to the equipment, i.e. field notebooks, standardised analysis of non-linear cover scores

quadrat relocation much easier in some habitats vegetation is usually layered, percentage cover (see Appendix 5). values can add up to more than 100%. The advantages and disadvantages of permanent This method of describing the vegetation versus temporary plots are discussed in more detail involves listing the species present within the sam- in Part I, Section 2.3.2. However, recent thoughts ple area, and attaching to each species an assess- are that monitoring schemes based on randomly ment of abundance. A number of recording located permanent quadrats should be avoided formats and techniques have been in place for unless minimising sampling variation is of prime many years; the most frequently encountered and importance. applied include the DAFOR, Braun–Blanquet and Cover estimates provide a good description of Domin scales, which are alternatives to estimating the contribution that each species makes to the the actual percentage cover. The Daubenmire scale vegetation community, and they are sensitive to is used for estimating cover alone but is not widely short-term fluctuations in season or management. used. The most widely used method in recent years One major advantage of cover as a quantitative has been the Domin scale, which is most frequently measure is that different plant groupings (mosses, encountered by ecologists in its use by the NVC (see herbs, grasses and shrubs) can all be evaluated in Section 6.1.6). comparable terms. If the vegetation has a distinct A once widespread approach that is now rarely layered structure (i.e. shrubs and undergrowth), used for quadrats is the DAFOR scale, which com- the cover of species in each layer is measured sepa- bines subjective assessments of frequency and rately (Bonham, 1989). Cover is normally expressed cover into five classes: dominant, abundant, fre- as a fraction, percentage, or amount of cover on a quent, occasional and rare. There are no defini- scale or index basis. It must be remembered that, as tions for these classes. Prefixes are also used to 204 6 METHODS FOR SURVEYING HABITATS

refine and qualify assessments by using terms identified and scored. Time taken will be further such as ‘very’ or ‘locally’. These prefixes have been dependent on quadrat size, vegetation diversity widely applied but frequently misused. Some sur- and surveyor experience. For example, a 2 m 2m veyors have modified the DAFOR scale with quan- quadrat on a species-poor heathland may only titative cover estimates (e.g. the ROFAD scale: < 5% require 5–10 min to record, whereas an equivalent rare, 6–20% occasional, 21–50% frequent, 51–90% quadrat on a species-rich grassland may require up abundant, 91–100% dominant; see Williams et al. to 30 min. These times exclude that required to (1998)). mark permanently or relocate the site of a quadrat DAFOR values are especially subjective and if this is necessary. Time efficiency can also be imprecise and therefore of limited use for monitor- increased with additional surveyors. ing. Different observers tend to have different defi- Recording can also be slower in wet vegetation nitions for the terms. Given the variability of and in very bright sunlight. It is also easier to miss DAFOR ratings they will only indicate change in species under these conditions. species abundance (and therefore be useful as sig- Time savings can be made if certain species or nals for action) if the change is very large, or if groups of species are omitted (especially species smaller changes are consistent over a number of that are difficult to identify quickly in the field, years. This may be useful if monitoring only needs such as certain bryophytes or vegetative grasses) to detect an obvious disastrous change at a site but the resultant data may be of only limited use. (Byrne, 1991). Savings in time can be re-allocated to recording The Braun–Blanquet and Domin scales give more sites or quadrats. more information than DAFOR, but are still subjec- Fewer quadrats are needed than for presence– tive and are affected by the same over- and under- absence methods (Section 6.4.3) to detect a given estimating problems for certain species as is level of change. DAFOR. Domin values vary greatly with observer and species condition. Expertise required More recent monitoring methods have looked at Considerable expertise is required to be able to the value of recording presence–absence rather identify correctly the full range of plant species than cover as a means of vegetation monitoring, (including bryophytes and macrolichens) typically with frequency as the favoured approach (Byrne, recorded in cover value assessments (see Appendix 3 1991; Rich et al. 1991; Hodgson et al., 1995). These for identification references). This skill can be developments have aimed to produce more consis- especially demanding for vegetative material. tent data, and have been favoured because moni- Experience is further required to estimate cover toring is comparatively quick, they reduce the values to a consistent level, although even then amount of observer error through removing the they are generally inaccurate. need to record cover values, and they are less tiring to carry out. These frequency methods are Equipment required described in Section 6.4.3 and are probably more Temporary quadrats require some form of delimi- appropriate for most vegetation monitoring pur- tation to ensure accurate recording. There are poses other than where estimates of cover and many alternatives, some constructed beforehand density are specifically required, e.g. for NVC sur- and others constructed on site. The latter mostly veys (Section 6.1.6). consist of pegs (e.g. metal skewers or tent pegs) and wire, string or cord to link between the Time efficiency pegs. Hammers or mallets are sometimes required Considerably more time is required to estimate to push the pegs into hard ground. There are scores or cover values than is needed to record advantages to using thick cord or line: it is less simple presence–absence data. This is further prone to tangling and stretching and it often increased if bryophytes and lichens must be copes better in wet conditions. Plastic-coated cord 6.4 Ground and shrub vegetation 205

may be preferable to string. Length should be reg- chances of detecting species, and are therefore also ularly checked as it can change according to envir- more likely to improve observer consistency, even onmental conditions and stretching. It is important though they have larger edge effects (Leach et al., to maintain constancy in the shape of the quadrat; 1992). If the data are to be used for NVC analysis, a set-square or other means of triangulation is quadrat size must be consistent with those used by needed for measuring right angles. NVC surveys (Box 6.11). An alternative method, which is easier to use in Second, a sampling strategy needs to be the field (but harder to carry around between sam- designed. This is complex and itself involves a num- ple points), is a pre-made square (of wood, plastic or ber of key decisions (outlined in Part I, Figure 2.6) metal). These can be further subdivided into grids including selection of the appropriate means of (by using wire or string at regular intervals along locating samples (i.e. randomly or systematically), the quadrat margins), which can considerably optimisation of the sampling (e.g. by stratification improve the accuracy of cover assessments. of the site and/or by multi-level sampling) and the Field notebooks, clipboards or weatherwriters calculation of the number of samples needed to and specially designed recording cards are tradi- provide sufficient precision to meet the monitor- tionally used to collect floristic data. These meth- ing objectives. These issues are described in detail ods of data capture require the further stage of in Section 2.3. transferring the information to a computer-based Once each quadrat has been placed, a list of spe- and/or paper filing system back in the office. Much cies is recorded and each species assigned a value on time can be spent on this, and errors in data tran- whichever measurement scale system you are scription can occur during this process. To allow employing. To increase accuracy this normally more time for data interpretation, records can be involves placing the species in a broad category to captured in the field by using a small hand-held begin with, and then refining the record if necessary computer, although it is possible that recording later in the recording process (Bonham, 1989). errors may be more difficult to check with this Cover estimates can be made more accurately by method of data capture. Trials in the Unit of division of the quadrat area into smaller units; this Comparative Plant Ecology at Sheffield University makes estimates more objective by concentrating showed that computers were less efficient than the area of search, but takes more time. paper when used for direct field recording. The range of cover values for each ‘layer’ is given Optical data scanners do not cope well with from 0 to 100%, and possibly divided into a number muddy or creased field cards. However, consider- of categories, with each category assigned a rating able developments are obviously occurring in this or scale. Use of a scale is optional but it recognises field and this form of data entry may become more the low accuracy of cover measurements. Most common in future. scales have unequal class intervals, which allow The marking and relocation of permanent quad- easier estimation of cover-to-area relationship but rats is covered in Appendix 5. are harder to analyse statistically. A finer breakdown of scale toward the lower scale values allows Field methods better estimation of less abundant species. Before embarking on a quadrat survey, a number A more elaborate approach, again little used in of key decisions must be made. First, a decision recent years, is the Braun–Blanquet scale, a semi- has to be taken on the optimum quadrat size; this quantitative method, which gives a combined esti- is discussed in Appendix 4 (and see also Box 6.11). mate of abundance and cover. The sampling unit is Quadrat sizes normally vary from 1 m 1m to called a ‘releve’ and its size is based on the minimal 4m 4 m, although in certain species-poor moor- area concept. Cover is measured on a scale based on land habitats 10 m 10 m may be more appropriate. a range of percentage cover values (see Table 6.5). The use of smaller quadrats is normally favoured as A second scale that measures the grouping of a they are quicker to set up and record, increase the species is less widely used. 206 6 METHODS FOR SURVEYING HABITATS

Box 6.13 Frame quadrats: likely problems and than with scales that have broad categories (Bonham, solutions 1989). DAFOR values are especially subjective and impre- The more complex the habitat or vegetation commu- cise and therefore of limited use for monitoring. nity (particularly grasslands, which can often consist of Different observers tend to have different definitions a diverse and dense mixture of plants), the more likely for the terms. Given the variability of DAFOR ratings, it is that differences will occur between recorders. they will only indicate changes in species abundance Some plants can be especially challenging to identify, rather than quantifying any change. particularly small non-flowering individuals of grass Small species tend to score lower than conspicuous and sedge species. Even the same observer re-recording ones. Similarly, a species in full flower is likely to the same quadrat can produce different lists receive a higher rating than one that is in a vegetative (Robertson, 1999). condition at the time of sampling. Species that form Visual estimates of cover by means of the Domin or clumps are also more conspicuous than species that a related scale will not necessarily pick up small are more evenly scattered and would be preferentially changes in abundance, particularly if the recording is classed in an abundance scale (Kershaw & Looney, not carried out at both times by the same observer 1983). This applies to all methods of estimating cover. (Greig-Smith, 1983). It is certainly not easy to detect, for Cover can be particularly difficult to estimate accu- example, a 10% change in cover from 50% to 40% for a rately in areas of diverse vegetation and tall vegetation. species; both would be given the same value if the The Braun–Blanquet and Domin methods give more Domin scale was used. In any event, there would information than does DAFOR, but are still subjective always be uncertainty over whether a detected change and are affected by the same overestimating problems in cover was a reflection of the changed abundance of for certain species as DAFOR. the species or was due to observer error (Hodgson et al., Differences between surveyors can be reduced, at 1995). least to some degree, by training. More consistent Even an experienced observer may assign a species results can also be achieved by defining the values or to a scale value lower or higher than that actually scoring terms more precisely. The use of pairs of occupied by the species. Because the mid-points of observers will produce more consistent results each class interval are widely spaced, there can be a (Hooper, 1992) but means that more expense will be large variation in data between investigators. In addi- incurred. Cover estimates made by using mini-quad- tion, in a species-rich herbaceous community errors of rats (Section 6.4.3) or nested quadrats (Section 6.4.4) estimates are more likely with finer scale intervals will also be less prone to error.

The Domin scale is a modified Braun–Blanquet It is convenient to record species lists and rat- approach, and is now the most widely used scale. ings onto standard survey cards; the area covered The increased number of divisions (which often by the species list should be clearly recorded relate to fractions, e.g. 1/2, 3/4) (see Table 6.5) (Byrne, 1991). enables a more detailed assessment to be made of Many communities contain species that are able plant coverage; a relatively high degree of consis- to coexist because they occupy a different temporal tency can be obtained with experienced recorders. niche. Therefore, the vegetation should be However, if you have to decide on the exact percen- recorded at a time of year when the majority of tage cover to obtain a Domin value, more informa- species are likely to be visible above ground, large tion is maintained by using percentage cover than enough for easy identification and before any by use of the Domin value. The use of the Domin major perturbation of the site occurs (e.g. burning, scale within the context of the NVC is described in introduction of grazing or haymaking). However, Section 6.1.6. this may not always be possible. Sampling in future 6.4 Ground and shrub vegetation 207

Table 6.5. The Domin and Braun–Blanquet scales

Braun–Blanquet Value Domin scale scale

10 91–100% — 9 76–90% — 8 51–75% — 7 34–50% — 6 26–33% — 5 11–25% 76–100% 4 4–10% 51–75% 3 <4%–frequent 26–50% 2 <4%–occasional 6–25% 1 <4%–rare 1–5% + Insignificant: normally <1% 1–2 individuals with no measurable cover years should always be carried out at the same time care should be taken to check that the transformed of year as the initial survey, although flexibility data meet the assumptions of parametric tests. in some years may be required to accommodate Cover scales are non-linear, so values (even from climatic variations (i.e. early or late summers). randomly located quadrats) cannot be analysed by Suggested times for surveying the floristic compo- parametric statistics; non-parametric statistics sition of vegetation are given in Box 6.9). based on ranks (such as the Mann–Whitney test) Some common problems and solutions that may (see Table 2.3) can be used. There has been some be encountered with frame quadrats are given in work on transforming Domin values so that para- Box 6.13. metric statistical analysis is possible (Currall, 1987). However, if it is intended to collect data suitable for Data storage and analysis parametric statistical analysis, it would be preferable This method will produce percentage cover or to collect accurate percentage cover values and use a Domin scores for a large number of species in suitable transformation, or use a linear scale. This each quadrat. Some way of summarising the impor- need not be any more time-consuming and the data tant changes is required. One way to gain a visual produced will be more detailed than Domin scores impression of changes in scores for each species transformed to percentages (Byrne, 1991). would be simply to plot Domin scores on the y axis Another means of identifying the more impor- and time on the x axis. This will demonstrate any tant changes between years is to list for each quad- clear increases or decreases in scores, and statisti- rat those species that have increased or decreased cal tests designed for ranked data (Section 2.6) can by a large amount (e.g. two or more Domin points) be used to test for significant changes over time. in a consistent manner over the sampling period. Percentage cover data are not normally distribu- A signal for action could be registered if a large ted, and either should be analysed with non- consistent decrease in a species was recorded in parametric tests or, more commonly, the data can a majority of quadrats, but several years’ data be transformed (Part I,Section2.6.3) into a closer would probably be needed before a signal could approximation of a normal distribution and ana- be registered, and only large changes could be lysed with parametric statistics (e.g. t-tests), but detected by this method (Byrne, 1991). 208 6 METHODS FOR SURVEYING HABITATS

Where Domin data are collected from quadrat * The inaccurate relocation of quadrats can ser- sizes comparable to those used for NVC surveys, iously bias the monitoring. the data can be used to establish and monitor the presence of NVC communities (see Section Other measures that may be taken in frame quad- 6.1.6). rats, such as vegetation height, presence–absence and sub-plot frequency, are discussed in the section on mini-quadrats below (Section 6.4.3). Summary of advantages and disadvantages of cover scores Advantages 6.4.3 Mini-quadrats * Cover values provide good descriptions of the con- Recommended uses tribution that each species makes to vegetation Frame quadrats can provide a simple, efficient and communities. reliable way of determining the frequency of spe- * Recording by using Domin values is widely used cies, assessed by recording the presence or absence (e.g. by NVC surveys) and understood. of species within each of a set of randomly located samples. They can also be used to monitor species Disadvantages composition if the total number of species in random mini-quadrats is recorded. * Estimation of cover can vary significantly from The most common application of the technique recorder to recorder. has been through the use of random mini-quadrats, * Recording all species present, including bryo- which was developed in the late 1980s by the phytes and macrolichens, can be time-consuming. England Field Unit of the NCC. Their method was designed primarily to monitor a series of grassland * Inaccuracies in identification occur for difficult transplants. species. Temporary quadrats are located either comple- * Domin and other cover scales are non-linear and tely randomly across the survey area or according therefore values, even from randomly located to a stratified random sampling approach (see quadrats, can only be analysed by using less Part I, Section 2.3.3 for further details). powerful non-parametric tests.

Time efficiency Summary of advantages and disadvantages of Experienced recorders are usually able to record permanent quadrats between 50–100 quadrats in a full day with the ran- Advantages dom mini-quadrat method. For planning purposes, assume a rate of ten (10 cm 10 cm) quadrats per * Reduced variation in data due to the effects of sampling means that fewer quadrats are likely to hour based on recording all species. The time taken be needed to detect a given level of change. to record quadrats is obviously slower in long vegetation and during periods of bad weather (Byrne, 1991).

Disadvantages Expertise required * Repeated recording may cause changes in the Considerable expertise is required to be accurate in vegetation. plant identification, especially for lower plants * Low numbers of plots, which were originally located and certain vegetative phases of grasses, sedges within representative areas of habitat, may become and rushes (see Appendix 1 for identification unrepresentative of the whole site over time. references). Cover values are not estimated, so * Establishment and relocation of quadrats can be experience of their estimation is not required for difficult and time-consuming. this method. 6.4 Ground and shrub vegetation 209

Mini-quadrats: summary of key points states of grasses, bryophytes and macrolichens are to be recorded Recommended uses Monitoring floristic change in Equipment required Quadrats, identification notes, relation to land management changes. Mini-quadrats field guides and basic recording equipment (i.e. field are relatively quick to record. More traditional quadrat notebooks, standardised recording forms); hand-held recording using cover values is less so computer on occasions Efficiency Individual quadrats are quick to record; Key methodological points to consider more quadrats are needed to detect change than stan- * Measuring presence–absence is very quick to record, dard frame quadrats but the estimate of frequency will be influenced by Objectivity Objective where only presence–absence quadrat size data collected * Preliminary trials should be carried out if necessary Precision Poorer than other methods but this is offset to establish optimum quadrat size and the number by its efficiency, and it can be quite precise if lots of required to achieve the desired level of precision quadrats are used * Patchiness in species distribution will reduce the Bias Frequency can be biased against species with a likelihood of a randomly placed quadrat finding more clumped distribution. Shoot frequency will be the species biased against smaller plants, but rooted frequency does not have this problem, although it is slower to Data analysis Dependent on material collected If assess accurately presence–absence recorded, random mini-quadrats are Expertise required Competence required in plant commonly analysed by a 2 test (see Part I,Section2.6.4); identification; special expertise required if vegetative for other measures see Data storage and analysis below

purpose of having a reasonably large number of Equipment required quadrats is to increase precision and the likelihood Field notebook, clipboards or weatherwriters and of detecting change. Abundance of each species is specially designed recording cards are traditionally objectively measured by its frequency (the total used to collect floristic data. These methods of of its occurrences in the quadrats: for example, data capture require the further stage of transfer- presence in 80 out of 100 quadrats equals 80% ring the information to a computer-based or paper frequency). These frequencies can then be analysed filing system back in the office. Much time can be to show relatively small changes in abundance. The spent on this, and errors in data transcription can point of using small quadrats is that only a small occur during this process; see also Section 6.4.2. area has to be searched, and this increases the chance that different observers will record the Field methods same list of species. There are no simple rules for determining quadrat Shoot frequency (which includes all species size for frequency surveys. The size of quadrat rooted within the quadrats plus any aerial shoots needed to monitor a species depends on the fre- within or overhanging the quadrat) is generally quency of the species and its distribution (see used for ease of recording. Measurements of root Appendix 4 and Box 6.11). However, for the widely frequency provide a less biased estimate of the used ‘mini-quadrat’ system for estimating species frequency of occurrence of smaller plants and have frequency in lowland grasslands, temporary quadrats been recommended for monitoring wherever- of size 10 cm 10 cm are used. In tussocky heath- possible (Robertson, 1999). However, assessing root land, 1 m 1 m quadrats may be more appropriate. frequency can be much more time-consuming and Generally, for presence–absence, at least 100 can cause damage to vegetation. Which definition mini-quadrats are required per survey area. The 210 6 METHODS FOR SURVEYING HABITATS

of occurrence is adopted is largely dependent on Use the second co-ordinate of the pair to deter- monitoring objectives. Where vegetation composi- mine the number of paces taken away from the tion in terms of sward or canopy is the attribute of marker (at 908) and place the quadrat at this concern, defining occurrence according to shoot point. Either return to the bamboo cane and con- frequency is appropriate. If the recovery of species tinue pacing to the next co-ordinate on the long or species populations is of concern, root frequency axis or else proceed directly to the next point. If should be monitored. the latter, it is important to return to a fixed The random location of samples should be car- landmark at intervals, to avoid cumulative loca- ried out according to the principles outlined in tional errors building up. An alternative is to use a Section 2.3.3. Once their co-ordinates have been GPS. Recorders should avoid looking at the vege- obtained, quadrats should be located and recorded tation when pacing out quadrat locations, so as to as follows. avoid any possibility of ‘choosing’ the final location. 1. First, establish and measure axes (i.e. the bound- 3. Place the quadrat on the ground once the correct aries of the monitoring plot) for determining ran- position has been reached. It is important to use a dom co-ordinates. Measurements may be paced standard method for this. This might be to face out or defined more accurately with tape mea- straight ahead and place the quadrat at arm’s sures. Use random number tables or a spreadsheet length, or to place the quadrat immediately in package such as Excel to generate random co- front of the right foot. The quadrat should be ordinates for the required number of quadrats. carefully lowered into the vegetation, avoiding Pairs of random co-ordinates can also be gener- pushing vegetation from outside into the quadrat ated from the VegAn computer package (Blake, area. This can be difficult with small quadrats in 1988). Enter random co-ordinates on the record- tall vegetation. If it proves very difficult a larger ing sheet. quadrat should be considered. 2. Work along the longer axis of the plot. Find the 4. Record litter, bare ground and vegetation height random number pair with the lowest co-ordinate (see Box 6.14), if necessary before the vegetation is for this axis. Pace the required distance along this disturbed by searching for species. Litter and bare axis and mark the spot (e.g. with a bamboo cane). ground should be assessed as amounts visible

Box 6.14 Measuring vegetation height and undisturbed individual at every placement of the rule. structure Exact protocols for this type of measurement should be decided and written down so that the method can be The most usual method for measuring height is to repeated exactly in the future. assess average height crudely by eye, with a ruler The principle that the rule is placed randomly or placed upright in the vegetation. systematically in the centre of the quadrat is Another widely used technique is to employ a long important. The quadrats in which the vegetation is ruler with a light disc that is able to slide along the rule. measured should either be randomly located or on a The disc is dropped from a certain standard height and stratified (restricted) random basis. stops when it comes into contact with the vegetation. For random samples, the results for mean height The height measured is not necessarily true vegetation from each quadrat are compared against the results of height, as it is affected by the weight of the disc and the other surveys by using t-tests or equivalent. density and flexibility of the vegetation, but it is quick For stratified random samples, an overall to record. estimatefor the site is calculated (see Part I) and Other methods are to pull the vegetation straight changes tested by using t-tests or non-parametric before measuring the length or to measure the tallest equivalents. 6.4 Ground and shrub vegetation 211

from directly overhead. If litter or bare ground Data storage and analysis is present but at less than 50% cover, a tick is Simple analysis of whether changes have occurred recorded. If the cover of litter or bare ground in the proportions of species present are normally is 50% or more, the figure ‘50’ is recorded. made through the preparation of contingency 5. Record all vascular plant species present within tables and analysed with 2 tests (see Part I)or the quadrat area (according to roots or shoots), G-tests (see Sokal & Rohlf, 1996). Long-term changes and bryophytes if required, using a tick for in species frequency (i.e. percentage of quadrats mature plants, a letter ‘S’ for a seedling, and a containing each species) may also be analysed tick and an ‘S’ for mature plants and seedlings. with, for example, Cochran’s test of linear trend. A seedling is defined as a plant having six or fewer If subdivided quadrats have been used to obtain true leaves or any plant with cotyledon leaves. a frequency measure for each quadrat, the propor- This distinction is not made for annuals such as tion (p) of sub-quadrats containing each species can p Fairy Flax Linum catharticum. The species contribut- be transformed by using a sin–1 ( p) transforma- ing most to cover (as viewed from directly overhead) tion (see Part I, Section 2.6.3) and usually analysed is noted by a circled tick. with parametric statistics. For further information see the statistical refer- Other measurements that can be made are ence texts listed in Part I, Box 2.5. abundance (number of plants of each species in each quadrat) and sub-plot frequency. To collect Summary of advantages and disadvantages sub-plot frequency data, the quadrat is divided Advantages into sub-quadrats (usually 25 or 100 divisions), and presence–absence of each species is recorded * The use of small quadrats increases species detec- in each to give a frequency for each quadrat. This tion and recording rates. measurement is more sensitive than simple * Presence–absence data are quick to collect. presence–absence in the whole quadrat and thus * Different field workers are likely to achieve very fewer quadrats will be needed to detect a given similar results. There is no need to mark and relo- level of change. cate permanent quadrats. Some likely problems and solutions that may * There are no problems with subjectivity and there be encountered with this method are outlined in is no need to allocate cover values, only presence Box 6.15. or absence.

Box 6.15 Mini-quadrats: likely problems and monitoring scheme. The England Field Unit found solutions 10 cm 10 cm quadrats to be suitable for monitoring the commoner species on grassland sites except where The larger the quadrat, the higher the frequency values the vegetation became very coarse or tall during the will be and the harder and slower it will be to search for monitoring period. However, if only selected species species. You should therefore use a quadrat size had been recorded (rather than all species), larger appropriate for the vegetation being sampled (see quadrats might also have been practical. Appendix 4). The appropriate quadrat size for fre- Although recording rooted frequency is considered quency measurements varies between species; a set of to be preferable, shoot frequency was used (in the nested quadrats of differing sizes may be required (see England Field Unit’s study) to save time in recording, as Section 6.4.4). it was felt that difficult and time-consuming decisions Some vegetation will be too coarse or too tall for (particularly with grasses) would have to made in very small quadrats to be used. However, once estab- determining whether or not a species was rooted lished, quadrat size should not be changed during a within a quadrat. 212 6 METHODS FOR SURVEYING HABITATS

Disadvantages a simple method for surveying and monitoring grassland vegetation by using a nested quadrat * The technique requires a large number of randomly design to assess species frequency (see Box 6.16 located quadrats, which are time-consuming to for information on the principles of nested quad- place. rats). The method was developed by the Unit of * Tall and coarse vegetation causes difficulties with Comparative Plant Ecology at Sheffield University, small quadrats. in conjunction with the Peak Park Planning Board * The measurement of shoot frequency can create and English Nature. Only herbs are recorded, to bias in over-representation of larger species. If this minimise the problems caused by identifying is a problem for the particular vegetation type, it other taxonomic groups: the presence of grasses, can be avoided by measuring root frequency but rushes, sedges or bryophytes is usually not this is more time-consuming. recorded. This nested quadrat method employs temporary 1m2 quadrats, which are located randomly within 6.4.4 Nested quadrats for Functional strips across a field or large plot. Each quadrat is Interpretation of Botanical Surveys (FIBS) subdivided into six nests, beginning at the bottom left-hand corner (10 cm 10 cm, 20 cm 20 cm, Recommended uses 30 cm 30 cm, 40 cm 40 cm, 50 cm 50 cm, 1 m This method, known by the acronym FIBS 1 m). The sequential examination of the nests (Functional Interpretation of Botanical Surveys) is encourages systematic searching of the quadrat;

Nested quadrats for FIBS: summary of key Expertise required Basic competence required in points plant identification, but some more difficult species are excluded from data collection Recommended uses Equipment required Quadrats, identification notes or guides and basic recording equipment, i.e. field * Simple method for monitoring functional changes notebooks, standardised recording forms; hand-held in the floristic composition of species-rich computer on occasions vegetation Key methodological points to consider * From ecological theory and a database consisting of a range of simple ecological, * Each site will normally be subdivided into strips or morphological and distributional attributes for sub-plots a large number of species, FIBS analysis can be * Quadrat size is 1 m2 and sampling is undertaken used to analyse why vegetation has changed within different size cells nested in this quadrat * Quadrats should be non-permanent and positioned Efficiency Relatively quick to record as only uses randomly a restricted range of species, and collects only * Recording is focused on broadleaved herbs, woody presence–absence data species and ferns Objectivity Objective as only presence–absence data * Presence–absence data are collected are collected. Subjective in that some species are omitted from data collection Data analysis The nested quadrat method uses FIBS Precision Poor, unless the recommended level of analyses (see Data storage and analysis) and plotting of replication is increased cumulative frequency against cell size. Floristic Bias Frequency can be biased against species with a change is interpreted by reference to the functional more clumped distribution, but nested quadrats do characteristics of the species present and utilises an compensate to some degree autecological database 6.4 Ground and shrub vegetation 213

Box 6.16 Principles and uses of nested quadrats trees (Shimwell, 1971). The ideas behind using nested quadrats are as follows. The principle behind nested quadrats is that a quadrat 1. The aim is to show the increase in species numbers is sub-divided so that the area of every subsequent with a corresponding increase in area. ‘nest’ is greater than that of the previous one. Large- 2. An implement such as a pin with a minutely small scale nested quadrats can be used where differently area can be placed in each nest at random to give a sized quadrats need to be used for different vegetation value for percentage cover. sizes and types (such as 1 m 1 m for herbaceous 3. The numbers of individuals of each species in each vegetation, 5 m 5 m for scrub and 10 m 10 m for nest will give a value of density and distribution and trees). The data from each quadrat are analysed sepa- show whether a species shows a clumped or evenly rately, the principle being that larger quadrats are spaced distribution. needed for larger vegetation in order to assess fre- 4. The presence–absence of a species in each nest will quency and density accurately. give a percentage frequency within the whole Small-scale nested quadrats can be used in which quadrat. the largest nest is, for example, 2 m 2m.The smallest area is surveyed first, and species presence The number of species found in a quadrat will and/or cover is recorded. Any additional species found increase as the size of the quadrat increases; plotting in the second nest are recorded, followed by the number of species against quadrat area will initi- additional species in the third and so on. It is usually ally show a steep slope. This relation will change quite advisable to stop only when there is a large reduction quickly to a situation in which there is little increase in in the additional number of species for each size number of species for a corresponding increase in increase, although in general this is 0.1 m 0.1 m for quadrat size; at this point, the optimum quadrat size vegetation dominated by cryptogams (i.e. plants can be determined for that vegetation type for the without true flowers or seeds such as ferns and Braun–Blanquet method. Sometimes the change in lichens), 1 m 1 m for species-poor grassland, 2 m slope is unclear, and the point of change can depend on 2 m for rank herbs and shrubs and 4 m 4mfor the axis scale. the different scales of the nests allows less common Time efficiency species to be picked up in the larger nests. When recording a reduced list of species, 40–80 Frequency is again used to measure relative abun- quadrats per day can be completed. If all vascular dance and changes over time. A reduced list of spe- plants are listed then 20–40 quadrats can be cies, which excludes those difficult to identify, has recorded per day, depending on the richness of been drawn up (Robertson, 1999). the vegetation. A similar nested approach has also been devel- In studies to date, a total number of 40 quadrats oped from this original application for the moni- per survey area have typically been recorded (but toring of Environmentally Sensitive Areas (ESAs) see Field methods below). in England, which comprises a fixed unit (stand): a rectangular area of 32 square sub-units (nests) in an 8 4 grid. Each holds a series of cells of Expertise required increasing size. The size is chosen to reflect the Some expertise is required to ensure accurate plant overall scale of the vegetation and is usually a identification, but as many of the difficult species compromise between being large enough to are omitted from data collection, less expertise is encompass the majority of species present and required compared with alternative recording small enough to be managed within available methods. On certain occasions more expertise is resources (Critchley, 1997). required for certain grasses, sedges and rushes 214 6 METHODS FOR SURVEYING HABITATS

(see Appendix 3 for identification references). maximised. However, environmental gradients Cover values are not estimated, so experience in need to be taken into account. their estimation is not required. Shape and size of the site Even if the site is irregular in shape, the strips Equipment required should still be approximately equal in size. If a Field notebooks, clipboards or weatherwriters and site is greater than 2 ha in size, it may be inap- specially designed recording cards are used to propriate to subdivide the whole area into five collect floristic data. These methods of data strips, because quadrats will have to be placed at capture require a further stage of transferring the very low densities. This poses no problem if the information to a computer or to a paper filing sys- vegetation is relatively homogeneous; however, tem back in the office. This can be time-consuming, this may not always be the case. and errors in data transcription can occur during this process. A bar code reader could be used. Choice of species Species lists, together with their bar codes, are pro- A reduced list of species should be considered; for duced on a laser printer and copied on a high-grade most sites, grasses, sedges, rushes and bryophytes photocopier (Hodgson et al., 1995). should not be recorded. Exceptions include agricultural weeds and certain easily identified monoco- Field methods tyledonous dominants. The latter group can Subdivision of the site contribute greatly to the structure of the Provided that the site is greater than 1 ha and less vegetation. than 3 ha, the area should be subdivided into five The monocotyledons that it may sometimes be more or less equal strips, with boundaries delimited appropriate to record include: Brachypodium pinna- as far as possible by the use of existing features (e.g. tum,1 Bromus erectus,1 Calamagrostis spp.,1 Carex acuti- walls or vegetation boundaries) and marked on to formis/riparia,1 C. paniculata,1 Deschampsia cespitosa,1 site plans. Compass bearings and permanent mar- Glyceria maxima,1Juncus acutiflorus,2 J. conglomeratus/ kers can be further used to delimit strips. If there is effusus,2 J. inflexus,2 J. squarrosus,2 J. subnodulosus,2 more than one management unit, each must be Luzula sylvatica,1 Molinia caerulea,1 Nardus stricta,1 monitored separately. Further subdivisions may be Phalaris arundinacea1 and Phragmites australis.1 required to take into account variations in topogra- (The number beside each name identifies the phy and vegetation (see Hodgson et al., 1995). method by which the species should be surveyed The simplest situation is a homogeneous site, and monitored, as detailed below.) which can be subdivided into five equal strips. If Amongst the bryophytes, Sphagnum spp.2 should the site is sloping, factors such as soil depth, nutrient be included, but all other species should be ignored. status and hydrology are likely to vary along the slope, so the site may need to be subdivided along Method of recording contour lines. Where there is a mosaic of plant Eight randomly placed quadrats should be recorded communities it is sometimes difficult to agree on from each strip or sub-plot, making a total of 40 exact boundaries, but where distinct vegetation quadrats for the complete site, except for smaller types are separated by a natural boundary a modifi- sites, where the number of quadrats would be 8 cation of the sampling method may be feasible and the number of strips. However, it should be noted desirable. that if analysis of the frequency of individual spe- Where no natural boundaries exist, effects of cies over time is required, then a change would management on vegetation should still be moni- need to be quite large (perhaps around 30%) before tored by aligning the strips in such a way that the it would be found to be statistically significant, chances of detecting differences in the intensity of depending on the confidence level required grazing or other site management practices are (Robertson, 1999). 6.4 Ground and shrub vegetation 215

Box 6.17 Nested quadrats: likely problems and This problem of quadrat size is overcome with the solutions nested quadrat approach in which, if a species is not found in the smallest cell of the quadrat, it is then One major problem with very small quadrats is that looked for in a succession of progressively larger cells they will provide useful data for only the very com- within the quadrat. monest species. Species of lesser abundance will be The method assumes that dicotyledons and recorded too infrequently to be included in the mon- monocotyledons are equivalent groups. They are not: itoring exercise. Equally, if a larger quadrat size, which there are a few monocotyledonous annuals and many is more suitable for the less abundant taxa, is more wetland monocotyledons. Initial tests suggest that, employed, the most abundant species will be present provided monocotyledonous dominants are included, in such a high proportion of the quadrats sampled and the method is defensible. However, it must be empha- at such high population densities within each quadrat sised that it is recommended only when the resources that it is unlikely that any change in their abundance available for monitoring work are not sufficient to carry will be detected. out more detailed surveys (Hodgson et al., 1995).

Where two or more recorders are involved, they recorded. These species will therefore be scored should all record quadrats from all five strips on on a scale from 0 to 4. the site to: 2. Taller, easily identified, ecologically important, highly visible species (identified with superscript2 * assist in discussions and facilitate agreement on above, i.e. rush species) should be recorded as for taxonomic problems; and herbs (see above). * prevent systematic sampling errors between areas that might arise due to different recorders. In addition, simple habitat information (amount of bare soil, litter, bryophytes, etc.) can also be col- For each 1 m2 quadrat the species present in lected by using procedure (1). When 50 cm 50 cm the bottom left cell are noted. Subsequently, records quadrats are used for this procedure, they should are made of the additional species present when the be placed sequentially in a clockwise order. This cell size is increased successively to 20 cm 20 cm, will prevent recorders being uncertain about 30 cm 30 cm, 40 cm 40 cm, 50 cm 50 cm and where to place the next quadrat. Refer to Box 6.17 100 cm 100 cm. for some potential problems with nested quadrats, The very smallest seedlings should be ignored and their possible solutions. because of identification problems, but larger ones with cotyledons and at least three true leaves should Follow-up survey be included. Herbaceous species are recorded only if Follow-up surveying is recommended every 2, 3 or they are rooted in the cell, but woody species are 5 years depending on the habitat. The procedure is included if a living stem is in the cell. basically identical to that of the initial baseline The additional monocot species should be survey except for the following. recorded by one of the two following procedures. * Monitoring should be restricted to herbs and to 1. In the case of tufted or stand-forming species that the important grasses, sedges and rushes present are obviously apparent in unmanaged habitats in at least 10 quadrats in the baseline survey. but which may be harder to see in shorter vegeta- * Important agricultural weeds should be moni- tion (identified by superscript1 above), the num- tored on each occasion irrespective of their fre- ber of 50 50 cm2 cells within the 1 m2 quadrat in quency to obtain information on the effect of which patches occupy at least 10 cm2 should be management on adjacent farmland. 216 6 METHODS FOR SURVEYING HABITATS

* The list of species for monitoring should be updated analysis for detecting and interpreting floristic on every third visit, as species that were initially rare change); and may become sufficiently widespread for inclusion. 3. a comparison of the characteristics of the differ- * Repeat surveys should be recorded at the same ent strips or sub-plots (to examine whether the time of year as in the original survey. This will site is heterogeneous and whether floristic help to ensure that contrasted phenological pat- change is occurring across the whole site or is terns of growth among the species present do not restricted to certain areas). distort the results. Summary of advantages and disadvantages Data storage and analysis Advantages Analysis of FIBS data is complex, and cannot be described in detail here. For the full method, refer * Smaller quadrats are quicker to record, improve to Hodgson et al. (1995). A brief discussion is pre- inter-observer consistency, and increase species sented here. detection rates. The first stage of analysis is to identify whether * Presence–absence data are quick to collect. there has been any change in the abundance of the * Different field workers are likely to achieve very monitored species. Two procedures may be similar results. employed. * The use of nested quadrats circumvents problems related to the optimal quadrat size in relation to 1. An ‘exact’ method involves curve fitting, in which plant abundance. cumulative frequency is plotted against cell size. * There is no need to mark and relocate permanent It is then possible to identify whether a species has quadrats. increased or decreased, and whether change has * There are no problems with subjectivity; there is occurred over the whole site or in only part of it. no need to allocate arbitrary cover values. The differences between the curves at different * Recording concentrates on broadleaved herbs, times can be statistically assessed. woody species and ferns to minimise taxonomic 2. A simpler method can be used to calculate a value errors. for changed abundance for each species in each * Sites are subdivided to maximise the chances of cell size, although this is a less satisfactory detecting the localised incidence of vegetational method of data analysis. change. * The FIBS method of data analysis can aid interpre- Floristic change is interpreted by reference to the tation of floristic change. functional characteristics of the species present, and utilises an autecological database (see Hodgson et al., 1995). Briefly, the ecological characteristics of Disadvantages declining species are compared to see if trends can * The method involves a low level of replication and be identified and attributed to changes in grazing, precision, and hence only large changes are succession, etc. For example, if annual species that detectable. require moist conditions appear to be declining, this * The plant species used for monitoring are could be linked to periods of drought or increased restricted, and this may not be appropriate for drainage. some monitoring purposes and habitats. FIBS analyses should be carried out on: * Analyses are complex and will only become user- 1. the characteristics of the initial vegetation (for friendly once a final protocol has been agreed and reference, for deciding frequency of monitoring appropriate computer programs written. and for comparing different sites); * The method is only really suitable for the more 2. a comparison of the characteristics of ‘increased’ species-rich vegetational types (i.e. mesotrophic and ‘decreased’ species (the main part of the and calcareous grasslands). 6.4 Ground and shrub vegetation 217

6.4.5 Point quadrats Time efficiency The recording of point quadrats is very time- Recommended uses consuming and laborious. The technique can be Point quadrats are used in short vegetation when very slow and requires considerable dexterity, very accurate estimates of cover are required, par- especially in dense vegetation. ticularly in the short term. Vegetation is recorded by passing long needles or pins down through vegetation and noting either the first or all species Expertise required touched. The method can be applied to single Expertise and skill are required, both to identify pins repeated many times, but more often pins are the species of plant touched by the points, and grouped into frames to make recording easier. If ten also to operate the point quadrat equipment. It is pins are used in a frame, percentage cover is esti- difficult to free-handedly lower a pin steadily and mated at 10% intervals. Point quadrats can also be vertically through the vegetation while also noting used for recording canopy structure, which is often touches and identifying species. important in grazing studies (Bullock, 1996). Point quadrats can give precise estimates of cover, although the estimation of percentage Equipment required cover for different species can vary with the pin A point-frequency frame consists of a wooden or a diameter (Goodall, 1953). They are best used on metallic frame with two legs and two cross-arms simple, short and unlayered vegetation; tall, tus- (see Levy & Madden, 1933). The cross-arms have ten socky or layered vegetation is harder to record or more perpendicular equidistant holes. Steel rods because of the large number of touches (Goodall, or wire pins are slid through the holes. You can use 1953). Point quadrats are very sensitive to changes the same pin for each observation or use a separate in structure and composition of the vegetation and pin for each hole. However, working with a single are best used for analysing short-term effects. They pin is slower than using multiple pins. The size of are of less use for long-term studies. the frame can be designed to suit local vegetation

Point quadrats: summary of key points Key methodological points to consider

Recommended uses * Location chosen in similar manner as for frequency quadrats (Section 6.4.2) * Estimation of cover in short vegetation (< 20 cm), in * Decide beforehand whether to record first hit or all which a high level of precision is required hits Efficiency Very time-consuming * Choose pin spacing to suit vegetation pattern Objectivity One of the most objective methods of * Care is required when lowering pins estimating cover * Avoid windy days to minimise plant movements Precision Precise in short vegetation in still conditions * Repeat monitoring must use pins of the same Bias Generally low diameter Expertise required Skill required to operate equipment and identify every leaf touched, particularly for Data analysis Single pins are analysed as for grasses and sedges presence–absence data, but pins grouped in quadrats Equipment required Point frame quadrat and are analysed in the same way as sub-plot frequency standard field recording equipment data (Section 6.4.3) 218 6 METHODS FOR SURVEYING HABITATS conditions, such as sward height and vegetation Data storage and analysis patterns, which will determine the spacing of Data from single-pin frames equate to frequency pins and height of the frame. data and can be analysed by a 2 test for fully randomised samples (see Part I). Field methods If pin frames have been grouped to form ‘quad- Samples should be taken at an appropriate number rats’, the data can also be analysed in the same way of locations as described in Part I, Section 2.3. as sub-plot frequency data: see Section 6.4.3 and Lowering pins steadily through vegetation is Byrne (1991). difficult; it is generally easier either to push the point into the soil and note touches along its Summary of advantages and disadvantages length (in this case the point diameter must be as Advantages smallaspossible),ortouseapointframethat * Point quadrats are considered to be the most supports ten points. The supporting rod is pushed objective way to estimate cover. Points can be into the ground, and readings are taken at each considered as plots with a very small area, and hole in the crossbar. A record is made of each there is minimal error or personal bias when species touched by the point of each pin as it points are used: either the point contacts a part descends. of a plant, or it does not. A decision also needs to be made over whether * The canopy structure of short vegetation cannot to record first hits only or to record all hits. be sampled in any other way. Recording first hits only is quicker and easier, par- * Small changes in plant cover can be detected ticularly in taller vegetation, and is sufficient to accurately. provide data on presence or absence of species. Recording all hits on a species gives a measure of Disadvantages ‘total cover’ of a species, a measure that reflects the size of plants as well as their abundance in the * Point quadrats tend to underestimate the overall vegetation (Bullock, 1996). contribution to the vegetation of erect-leaved spe- If canopy structure is being measured, inclined cies and overestimate the cover of species with point quadrats are often used. These are simply nearly horizontal leaves. The attitude of the leaves point quadrats that are lowered through the vege- of most species varies with environmental condi- tation at an angle (usually 32.58 to the vertical) tions (Bonham, 1989). (Warren-Wilson, 1960). In this case, as well as * The area sampled is very small, so large numbers of recording all the hits of the point quadrat, the samples are needed to detect the rarest species. height of each hit is also noted. * Direct measures of cover by point quadrats are too Box 6.18 highlights the main problems, and laborious and time-consuming to be appropriate their solutions, when using this technique. for most monitoring purposes.

Box 6.18 Point quadrats: likely problems and training and experience and choosing to record only solutions on windless days. Because the total area sampled is small, only the Point quadrats are time-consuming to record and every more frequent species can be sampled by using pin leaf touched needs to be identified: this is often diffi- frames. It would be easy to increase the number of cult. Errors can occur from other sources such as samples if only a few target species were to be movement of plants by wind or improper lowering of recorded, but this may still be insufficient for some the pins by the observer. This can be rectified by species. 6.4 Ground and shrub vegetation 219

6.4.6 Transects touch the tape at standard distances (e.g. every 10 m) or randomly allocated distances along the Recommended uses transect. Alternatively, percentage cover can be There are a variety of different types of transect, each estimated by measuring the length of transect used for a different purpose. These are summarised line occupied by each species and using this to in Part III,Section10.1,Figure10.1. For habitat mon- calculate the percentage of the length of the trans- itoring, the most commonly used transects are line ect that is ‘covered’ by the species. intercept transects, point intercept transects and belt A point intercept transect involves recording transects. Other transect types are used for species presence–absence of species at set points along monitoring and therefore may be required for mon- the line. This can be used to estimate frequency. itoring species attributes of habitat features. Refer to Line transects can be used to measure density by Part III for details of these methods. recording the perpendicular distance of plants A line intercept transect, sometimes called a from the transect line. For further information ‘one-dimensional transect’, is used for making con- see Bonham (1989) and the discussion of distance tinuous observations along a line. The method con- sampling methods in Part III, Section 10.4. sists of measuring the intercept of each plant along Belt transects are normally used to monitor a line, which is usually placed on the ground, to changes in vegetation along a gradient or across a give a measure related to the density of plants. For community boundary. They consist of frame quad- longer transects, plants are only recorded that rats of any size laid contiguously along the length

Transects: summary of key points Expertise required Comprehensive plant identification skills normally required (unless only Recommended uses selected indicator species are being monitored). The line intercept method is easily learnt. Additional belt * Line intercept and point intercept transects can be transect expertise required is dependent on the used for measurements of cover and frequency in vegetation measures being collected tall or sparse vegetation Equipment required Measuring tapes (or another * Belt transects are particularly useful for monitoring form of marking distance); permanent markers at each vegetation changes along environmental gradients end if transects are permanent; frame quadrats for use or across vegetation boundaries with belt transects; standard field recording equipment Efficiency Line intercept and point intercept Key methodological points to consider transects can be efficient in areas of sparse vegetation; belt transects are time-consuming if all species are to * Randomly or systematically locate line transect be recorded locations * Determine appropriate length of transect(s) and Objectivity Subjective if the belt transect approach is mark each end (perhaps permanently) adopted with the use of cover values; objective if * Place line or tape at an appropriate height to the presence–absence is recorded vegetation (including ground level as an option) Precision Line intercept and point intercept transects * Belt transects are often permanent and located are precise; for the precision of belt transects, see across environmental gradients or community frame quadrats boundaries in question; follow other principles for Bias Counts of touches or estimates of cover will frame quadrats often depend on the height of the line transect; for other biases relating to belt transects, see frame Data analysis Data analysis depends on the transect quadrats method and sampling strategy used 220 6 METHODS FOR SURVEYING HABITATS

of the transect. Cover, local frequency or other Belt transects are time-consuming if all species vegetation attributes can be estimated for each are to be recorded and many quadrats are used, but quadrat, and the variation in attibutes along the they can provide detailed information on vegeta- transect can be determined. This information can tion changes. be compared between sampling occasions (for example, to see whether the extent of a plant com- Expertise required munity has changed). Transect methods are not complicated; surveyors As for frame quadrats, transects may be perma- will find the techniques straightforward once the nent or temporary. For general monitoring pur- technique has been used in the field. Botanical poses it is recommended that permanent identification skills are required (see Appendix 3 transects are not used unless minimising sampling for a list of field guides). variation is of prime importance (see Section 6.4.2 or Part I, Section 2.3.2 for a detailed discussion). An exception to this is where belt transects are delib- Equipment required erately placed across vegetation boundaries, for Equipment includes some type of line (wire, rope example to monitor changes in the extent of an or tape), two pegs for securing the line tightly at NVC community. In such situations, permanent either end, and a hammer for driving in the pegs. transects provide a precise and efficient means of Measuring tape will be needed to mark out dis- monitoring such changes, but steps should be tances along the transect. Frame quadrats are taken to ensure that transects are, and remain, required for use with belt transects (see Section representative, and that sufficient transects are 6.4.2). See Sections 6.4.2–6.4.4 for further details allocated to allow for lost samples. depending on whether standard cover or frequency When randomising the location of fixed-length data are required or FIBS methods are to be used. temporary transects, it is not necessary to rando- Standard field recording equipment (notebook, mise the direction of the transect; it is recom- pens, field guides, etc.) will be needed. A compass mended that all transects lie in the same direction may be required to orient transect lines. (Greenwood, 1996). However, it is important that all points within the study area are equally likely to Field methods be sampled. To achieve this, an area of one com- Before carrying out the transects, a sampling pro- plete transect length surrounding the study area gramme must be devised. This is a complex and must be included when start points are selected critical process and is discussed in detail in Part I, (Part I, Section 2.3.3); parts of transects that fall Section 2.3. outside the study area are ignored, but any frag- For line intercept and point intercept transects ment that falls within the study area should be the line or tape is stretched taut at a height at surveyed. which it will make contact with the vegetation canopy. If basal cover is being estimated, the line is placed at ground level. The length of each inter- Time efficiency cepted plant part is measured. The total length of Line transects are particularly efficient in areas the transect line and the total length intercepted by of sparse vegetation, although time needs to vegetation are used to estimate percentage cover. be set aside to mark out the transect prior to Tapes are often used for lines; intercepts should recording data. However, if the vegetation is be recorded on one edge only. The location of the dense, then recording all touches can be time- start and end of the transect line can be marked consuming, in which case point transects are with permanent stakes if monitoring is to be more efficient. Cover estimates will also be repeated with permanent transects. The length of more difficult where plants are small, indistinct transect used will depend on the type of vegetation and intermingled. being sampled. In general, cover in herbaceous 6.4 Ground and shrub vegetation 221

It should be remembered that if cover-abun- Box 6.19 Transects: likely problems and dance totals are increasing, it is not evident from solutions these totals whether species are spreading by expansion from small foci of living vegetation, or Parker & Savage (1944) tested the reliability of the whether the increase in abundance values is line intercept method. The data were reproducible caused by a more widespread but thinly scattered by the same observer but differed among observers. increase (Lindsay & Ross, 1994). The entire plant should be used for the unit of For permanent transects, a second approach, measurement to simplify data collection. which is less quantitative but provides a clearer See Sections 6.4.2–6.4.4 for information on pro- picture of the changes between transects for indivi- blems relating to frame quadrats if used as part of dual species, involves the simple mapping out of a belt transect system. each year’s data for a species. By comparing the ‘species transect maps’ from consecutive years and, particularly, comparing those for the baseline year communities can be estimated with short transects with the most recent data, it is possible to obtain a (less than 50 m), whereas long transects (50 m or good visual impression of spatial changes over time. greater) should be used in some shrub communities. Transects do not necessarily have to follow Summary of advantages and disadvantages a straight line (Bonham, 1989). Advantages If belt transects are used with frame quadrats, then see Sections 6.4.2–6.4.4 for details on record- * In certain vegetation types it may be simpler to ing quadrats. Problems with using transects, and use line transects than quadrats; they can provide their solutions, are presented in Box 6.19. more productive sampling in sparse vegetation and can be more practical in tall vegetation. They may also be easier to search more thoroughly Data analysis than quadrats of the same total area. There are a number of approaches that can be * Line transects are quicker to record than are taken, depending on the exact transect method quadrats. used and sampling design. * Belt transects can produce very detailed data, for Point intercept presence–absence data can be example for monitoring changes across vegeta- analysed by using 2 tests. If presence–absence is tion boundaries. measured at points along the transect, data can be * Line point transects are useful for measuring analysed in the same way as sub-plot frequency changes in total vegetation cover, although accu- data for quadrats (Section 6.4.3). racy depends on the length of line and number of A simple quantitative approach in which tem- points used per line. porary belt transects are used is to sum the cover- abundance or frequency values for each species Disadvantages across all the individual squares for all the transects, thus obtaining a form of cover-abundance * Transects intentionally directed along environ- value for each species for each year of monitoring. mental gradients or across habitat boundaries Changes in cover-abundance values from year to only sample restricted areas; all areas of the site year indicate overall shifts in species, although will not have an equal chance of being sampled, they provide little information about the spatial and this makes the extrapolation of results across character of these changes. Thus all the change the whole site problematic. may be due to the changes on a single transect, or * Transects are often not suitable for measuring the it may be a more widespread phenomenon, but the cover of individual species in habitats where drawing out of such information requires more plants are closely intermingled and vegetation- sophisticated analysis. type boundaries are not distinct. 222 6 METHODS FOR SURVEYING HABITATS

* Long transect lines produce underestimates of reasonably uniform with respect to stand age, struc- species cover when points are widely spaced, ture and dominant species. because several patterns of species may be crossed. However, estimates of total cover are unaffected Time efficiency by the length of line (Bonham, 1989). The time taken to complete a stock map will * Belt transects can be very time-consuming to depend upon the complexity of the wood being record. mapped and the level of detail required. It should be possible to map 20–50 ha per day with well- equipped and competent surveyors if not every 6.5 TREES AND WOODLAND STANDS detail is being recorded. 6.5.1 Stock maps Expertise required Recommended uses The identification of the dominant tree species is Many attributes of woodland can be monitored by necessary (including the identification of deciduous an adaptation of the standard forestry technique of trees in winter if required). Surveyors also need to be stock mapping. This involves mapping the config- able to estimate stand age. This is easier for some uration of stands defined by (i) age; (ii) structure; and species than for others, but a degree of experience (iii) dominant tree species. This is simple enough in will be necessary for making this assessment. even-aged monocultures, in which boundaries are Surveying and cartographical skills are also usually sharply defined, but requires more elaborate required. procedures in semi-natural woods, mixtures and stands of a more complex structure. The result is a Equipment required map showing the pattern of compartments and sub- Appendix 6 summarises the equipment required compartments, the latter being stands that are for stock mapping.

Stock maps: summary of key points Bias Accurate identification of boundaries and species essential Recommended uses Expertise required The ability to identify tree species in all seasons is essential. Surveying and cartographical * Mapping compartments of woodland delineated by skills are also required similar stand characteristics * Monitoring species composition in terms of Equipment required Basic surveying equipment dominants such as ranging poles and tape measures if detail and * Monitoring age-class distributions at larger scales precision is required; otherwise, distances can be * Monitoring rotational management and open space measured by pacing (see below for details). OS base patterns map and vertical aerial photographs are necessary * Monitoring large-scale effects of natural disturbance Key methodological points to consider

Efficiency Time taken will depend of the character of * Need to classify stands by age of dominant species the wood * Consideration should be given to the size of the Objectivity Reasonable once classification is decided smallest unit that will be recorded

Precision Will depend on the scale of mapping Data analysis Data are presented in the form of chosen (usually 1 : 10 000 or more detailed) and maps; areas can be estimated from these maps by using the sharpness of boundaries between the methods applicable for aerial photography (Section compartments 6.1.3) and Phase I survey (6.1.5) 6.5 Trees and woodland stands 223

Field methods adjacent stands, and to map rides and roads on this To begin with, if good-quality aerial photographs basis. are available for the wood, these can be used to Estimates of age can either be made on the basis delineate obvious boundaries of different stand of the surveyor’s experience (to do this for many types (for example, patches of conifers can be read- tree species will require considerable expertise), or ily distinguished from deciduous trees; see Section by using an increment borer to take a core sample 6.1.3). These can be mapped on to a base OS map at from a representative sample of trees in each stand the required scale (usually 1 : 10 000). to obtain an average ring count. However, to obtain finer detail, some ground The level of detail recorded for stand structure survey work will be required, particularly for esti- will depend on the monitoring objectives. Briefly, mates of stand age. Survey techniques for wood- if precise ages are not required, trees can be classed land are described in greater detail by Kirby ( 1988). as seedlings, saplings, young trees, mid-aged trees, Briefly, sharp discontinuities in canopy compo- mature trees, over-mature trees and dead trees. The sition, age or stand structure should be identified. precise point at which, for example, a sapling In managed woods these are commonly correlated, becomes a young tree involves a degree of subjec- whereas in woods in which there has been little tivity, so the classifications should be decided in management intervention there will probably not advance of the survey (based on measurements be abrupt changes (except perhaps in areas that such as girth and height) and adhered to through- have at some point been cleared by natural distur- out the survey. It should be borne in mind that bance). Open spaces should also be treated as different species have different speeds of growth, ‘stands’. Where boundaries are poorly defined or and so criteria for classifying different species may follow tortuous configurations, arbitrary bound- alter. aries should be accepted if there is significant vari- The growth form of the dominant trees in each ation in stand characteristics. Well-defined tracks stand should be recorded as: maiden, coppice should generally be accepted as boundaries, even stool, tree singled from coppice, shrub, pollard when the stands on either side are identical. This or climber. Finally, estimates of height can be process is best initiated with aerial photographs used to partition vertical structure (ground layer, and subsequently refined and verified on the understorey layer, subcanopy layer, canopy layer); ground. stands can be differentiated on the basis of subca- One basic method for mapping is to lay out a grid nopy features as well as dominant canopy system in the woodland based on 100 m 100 m features. squares (or whichever size is most appropriate for the woodland), identified by using compass bear- Data storage and analysis ings, and record the dominant species and age (or The stock map is a reference document, which stand type; see Kirby (1988) and Peterken (1980, shows the patterns of habitats, the pattern of 1981) for details of stand-type classification sys- stand dominants and the pattern of age classes at tems) at each grid point. Lines can then be drawn the canopy level. The map can be revised after each on the map around clusters of points with similar forestry operation (if appropriate) or natural distur- stand types, giving an approximation of compart- bance. If the wood is treated as non-intervention, ment boundaries. the stock map may be revised every 10 years or so. Most forestry stock maps include glades as sepa- Stock maps should be stored as for Phase I sur- rate sub-compartments, but treat rides and roads as vey maps (Section 6.1.5). The stock map is used to boundaries. Monitoring for nature conservation, examine age-class distribution at the larger scales, however, requires that track, ride and road charac- rotations and open space patterns. Comparisons of teristics be monitored. It should be possible to successive maps can be made by eye to gain a visual devise a classification appropriate to the size, impression of trends in the data. However, for based on usage, width and degree of shade from more rigorous analysis, the areas of each stand 224 6 METHODS FOR SURVEYING HABITATS

type can be estimated by using the same proce- advantage that any change observed is real within dures described for aerial photography (Section the limits of the plot and can be related to the 6.1.3) and Phase I mapping (Section 6.1.5). performance of individual trees and shrubs. Permanent plots can also be illustrated with fixed- point photographs (Section 6.1.4) and used to Summary of advantages and disadvantages visually demonstrate and appreciate change. Advantages Permanent plots also allow the performance of * An easily interpretable map of compartments, individual trees to be monitored. The disadvantage rides, glades, etc. is produced, which can be used is the extra work required to mark plots and for monitoring purposes in itself or as a guide for archive the data. A further, though usually insignif- choosing areas for further investigation. icant, disadvantage is that the plot markers on the * Stock mapping could be carried out as part of a ground may actually influence what happens more detailed survey, thus reducing the time within the plot. taken to carry out two separate surveys. * Stock maps are reasonably quick to complete, pro- Time efficiency vided that a fairly coarse level of detail is being Permanent plots require a significant initial recorded. investment to generate the first record, but subsequent recordings usually take far less time to complete. Field recording is best done with two Disadvantages (or perhaps three) people. A person working alone * The level of detail is restricted to age, species and cannot readily move tapes, nor transfer repeat- structure of only the dominant tree species in edly from measuring to recording and back. Even each compartment. after the plots are clearly delimited for recording, * Mapping entire woodland areas may be problematic it is usually most efficient to have one book- and time-consuming, particularly when dense scrub keeper in control. is present and there are no sharp boundaries The time taken to record data depends on the between different stands. structure of the stand. Old growth lacking an understorey can be recorded quite quickly. Young growth containing many multi-stemmed trees and/ 6.5.2 Permanent plots or groves of saplings can be very time-consuming to record. In an average stand being recorded by Recommended uses three people, it should be possible to lay out and The use of permanent plots (either in the form of record six 20 m 30 m transect sections in a day. quadrats or transects) in which individual trees are Re-recording a transect is quicker if the amount of mapped and measured is the most detailed form of change has been small. Separate plots will take stand monitoring. They can be used for monitoring longer if precise relocation is required. changes in woodland composition and structure down to the scale of individual stems. Changes Expertise required recorded in several permanent plots can be aver- Surveyors must be able to identify all tree species aged and extrapolated to give an indication of the and assess their condition in terms of age, health, changes taking place over the entire woodland height, girth, etc. It is usually necessary to make area. If plots are sufficiently numerous and distrib- decisions about what to record and the degree of uted in a suitable manner, statistical interpreta- detail required before the monitoring work com- tions can be made. mences. An understanding of woodland succession Permanent plots are samples which are marked is therefore needed. In addition, familiarity with in such a way that the record can be repeated the techniques for quadrat or transect sampling exactly on the same ground. Permanence has the and data collection is necessary. 6.5 Trees and woodland stands 225

Permanent plots: summary of key points Expertise required The ability to identify tree species in all seasons, and to assess their condition, is essential. Recommended uses Familiarity with transect and quadrat sampling methods and techniques is also necessary * Monitoring changes in woodland composition and Equipment required Basic surveying equipment structure down to the scale of individual trees such as ranging poles and tape measures (see below for (including fallen dead logs) details) * Providing a time series of data on successional or other changes taking place Key methodological points to consider * Monitoring the amount of regeneration occurring * Recording permanent plots can be time-consuming, Efficiency Three people working together should especially when setting up new ones. The density record six 20 m 30 m transect sections per day (see of trees in the plots and the distance between plots main text for details) should be taken into account when deciding how Objectivity Good, as long as classifications (e.g. many plots to sample and what size they should be amount of canopy cover) and field methods are rigor- * It is essential that permanent plots can be accurately ously defined and adhered to relocated on subsequent visits. The plot markings must be durable and interference-proof Precision Good, providing plots are accurately relo- * The size and shape chosen for permanent plots will cated on return visits and measurements of tree loca- affect the type of change that they are capable of tion, height, etc. are accurate. Precision of estimates of monitoring; long transect belts will record grouping change extrapolated over whole woodland will depend and zonation changes more clearly than small on the number of plots and the percentage of the total square plots. However, small plots can provide a area covered better representation of the wood as a whole Bias Care must be taken when using permanent plots to estimate wider-scale changes. Data analysis Data can be held and processed by Unrepresentative plots, or too few plots, will give using a spreadsheet package. For analysis, a time unreliable estimates of compositional and structural series of changes in single plots can be produced, or change occurring through the whole woodland. Since changes in average plot composition, structure, etc. trees are generally non-randomly distributed, biased over time can be estimated and tested for statistical estimates of relative density can be obtained significance

The technique of fixed-point photography A compass is required to measure the locations (Section 6.1.4) is useful to provide a visual record of trees if circular plots are being used. A hyps- of changes in the composition or structure of par- ometer such as an Abney level can be used if accu- ticular plots over time. rate measurements of canopy height are desired.

Equipment required Field methods The equipment required is fairly basic surveying Plot shape equipment (Appendix 6). It should be borne in Plots can be circular or rectilinear in shape. mind that permanent plot markers should remain Circular plots require one central marker, whereas in place for many years; it is advisable to use long- rectilinear plots generally require a marker in each lasting materials, and to fix them securely in place. corner. Markers themselves are subject to decay, Galvanised metal posts are most commonly used. destruction and vandalism, so four markers should 226 6 METHODS FOR SURVEYING HABITATS

be more secure than one, but this increases costs co-ordinates in large plots is difficult unless the and the time taken to set up the plots. The usual ground is nearly level. compromise is to have two central posts marking the mid-line of the plot. The location of individuals within plots can be simply defined with both plot Data measurements shapes (bearing and distance for circular plots, x Individual trees can be mapped by recording the and y co-ordinates for rectilinear plots), but is some- co-ordinates of their centres to the nearest 10 cm. what easier with rectilinear plots, because compass Greater accuracy is rarely required, but may be bearings take longer to determine than do x and y necessary in dense groups of saplings. Large, co-ordinates and are usually less precise. multi-stemmed trees are best annotated to show The choice between using square plots and rec- individual stems. Dense clusters of stems from tangular belt transects depends on circumstances stools (e.g. hazel coppice) may not be worth map- and the overall pattern of sampling. ping individually, although each stem should be recorded. Although all individuals attaining 1.3 m * A large number of small (e.g. 20 m 20 m) square in height should be recorded, a minimum thresh- plots is a statistically superior representation of old for recording stems is usually 2–5 cm diameter the wood as a whole, which also allows whole-site at 1.3 m height. distributions to be assessed at the scale of the The features that might be recorded for each tree distance between plots. However, the effort or trunk of a tree during routine enumerations are: required to position and mark plots is substantial, species, height, trunk circumference (girth) or dia- and individual plots are easy to mislay over long meter at breast height (gbh or dbh), canopy position, intervals between recordings. Groups and transi- origin (e.g. coppice), health measurements, and indi- tions are difficult to detect and monitor. In addi- vidual characteristics (e.g. height of lowest branch tion, edge effects in small plots may be large. on large trees, distinctive shapes). Where large and * Transects laid out across the main directions of veteran trees are of special interest, some estimate variation allow groups and zonations to be detected of dead wood (Section 6.5.5) may be needed. and monitored. They require much less effort to position and mark. They are also proof against * Girth and diameter. Conventionally measured at neglect and vandalism, for transects can be 1.3 m (breast height), taken by standing above the re-established even if only two markers remain in tree if on sloping ground (a small nail driven into position. Location of individual trees is easy to thebaseofthetreeallowspreciserelocationof1.3m record by co-ordinates. However, single transects height on subsequent surveys). If this falls on an may not contain a valid subsample of the whole atypical section (e.g. a fork or rot hole), measure wood and do not allow whole-site distributions to immediately below. Calipers are available to mea- be assessed. The dynamics of stands within the sure diameter, but they are heavy, inaccurate on transect may be strongly influenced by events and irregular shapes and awkward in semi-natural thick- conditions in the stand outside the transect. ets; tapes are generally better all round. Although * Single large (at least 100 m 100 m) square plots tapes are available that read directly into diameters may allow groups and zonations to be detected from a girth, these do not give the accuracy neces- and monitored, but are more likely to represent sary to study the growth of individual trees. a single woodland type. They require a grid of * Canopy position and crown size. Useful for detailed markers, partly as security, but mainly to facilitate analysis of change. Best recorded at a somewhat accurate recording. The dynamics of stands within coarse level of canopy, subcanopy, tall underwood, a large square plot are less influenced than trans- short underwood; and large, medium or small. ects by events and conditions in the stand outside * Height. Not always useful for monitoring, and the plot (the centre of the plot being much further best avoided if unnecessary on cost–benefit con- from unrecorded stands). Recording accurate siderations. Where height measurements are 6.5 Trees and woodland stands 227

useful (e.g. when monitoring young regenerating Separating areas in which the ground is open or woodland), it can be estimated by standing back partly shaded is important. Gaps can be easily and counting approximate 2 m steps from bottom mapped on to scale charts of the plot by using indi- to top (the scout method). Use a hypsometer vidual trees as reference points and pacing out the for more time-consuming but more accurate edges of gaps viewed vertically from the ground. measurement. Canopy spread of individual trees can be esti- * Origin. Recorded by using a simple classification, mated by vertical projection of the canopy margins which will generally take the form: coppice, pol- on to the ground, taking two diameters at right lard, maiden, planted, naturally regenerated. angles. The greatest difficulty arises with tall, nar- * Health. For general use, a simple classification suf- row-crowned trees, for which the proportionate fices, usually a four-point scale from healthy and error when projecting spread vertically on to the vigorous to crown dead/alive only at base, which ground is high and the canopy spread is small, but recognises increasingly severe symptoms of ill as these trees will often be in closed canopy stands health or stress. Bark stripping by grey squirrels, the position of neighbouring trees and their ponies, deer, etc. can be similarly recorded (i.e. canopy form can be used as a guide. severely debarked, partly debarked, not debarked). Estimating the cover of each species in a plot is based on the convention that a tree wholly occu- Where individual large and veteran trees are being pies the area within its canopy spread, even though recorded, a more complex codification may be the foliage is thinly spread. Two approaches are necessary. Surveyors will have to devise codes possible: that are appropriate to the site and as objective and quantitative as possible, e.g. number of live 1. to record cover within equal cover bands of e.g. crown branches; proportion of circumference at 10%; and 1.3 m with live bark. 2. to recognise unequal cover bands, which are more Photographs of important or sample trees are discriminating at low cover values (Table 6.6). helpful. They allow unforeseen characteristics to be assessed, and they can be used to explain any The latter is generally most useful, even though it conventions used for classifying health, canopy does not allow cover to be averaged over a number position, etc. of plots; most species occur at low cover, so making Canopy gaps can be rapidly recorded and provide distinctions within the lowest cover bands conveys valuable information on gap-phase regeneration more information. opportunities and canopy disturbance rates. In sim- Permanent plots can be used to monitor regen- ply stratified stands they are easily defined, but in eration by assessing the numbers and population overlapping, multi-layered stands they need to be dynamics of seedlings and small saplings, and the carefully defined and will take longer to record. associated state of ground vegetation.

Table 6.6. Example of a canopy spread classification

Scale Description Scale Description

10 Complete cover 4 Below 5% cover 9 Above 75% cover 3 One large individual 8 50–75% cover 2 One small individual 7 33–50% cover 1 Saplings only 6 15–33% cover X Seedlings only 5 5–15% cover D Dead plants only 228 6 METHODS FOR SURVEYING HABITATS

Record species, numbers and condition accord- See Peterken & Backmeroff (1988) for full details ing to a standard procedure to estimate density of the use of transects. See Mountford & Peterken of regenerants. Condition can be measured by (1998) for an example of results obtained from height, degree of grazing/browsing damage, detailed recording of permanent transects. etc. Such records can be repeated on an annual basis at the same time of year if responses to a Data storage and analysis change in grazing pressure must be measured. Data storage Analysis of changes and the underlying factors Field records should be placed on to scale charts causing the changes is restricted by the lack drawn on graph paper, showing the location and ofinformationonturnover.Recordingofthis size of each stem. Additional notes can be refer- kind is relatively quick, so it is practicable to enced from these. Original field records should be uselongpermanenttransectsasabasisand retained and kept on file, even after data have thus obtain information on large-scale patterns. been transferred onto a computer. This will SNH has used very long transects of this kind in allow checks to be made and will permit future large sites by recording every 10 m in 100 m, workers to examine the original data for other counting saplings, etc., within 1 m of the line purposes if required. (see Box 6.21). Hard copies of computer databases and spread- Recording individuals precisely means that sur- sheets should also be filed, and backup computer vival, mortality and recruitment can be measured. files made for security. The basic data and records This requires mapping individual seedlings and of methods should be stored in separate locations, saplings, which is only practicable on a small again for security purposes. The locations and scale (e.g. 5 m 5 m). The scale of practicable contents of files should be kept on record, so that recording decreases as the density of regenerants any successor staff will be made aware of the exis- increases. If the issue is the survival of seedlings tence of the records and where they can be through the first year, recording will be necessary accessed. at intervals of 3 months. If the issue is the survival of established seedlings, recording at annual intervals at a constant time during the growing season Data analysis may be sufficient. Remains of regenerants that Analysis with a computer spreadsheet program such have died can often be found, and these help to as Microsoft Excel or Lotus 1–2–3 has proved satisfac- explain mortality factors. Analysis of these obser- tory. Input the data so that each line of the spread- vations is time-consuming. In all cases, supplemen- sheet represents one stem, which is given a code tary notes describing the stand and points of number. Each column represents an attribute of a interest are useful. stem (e.g. height, girth, etc.) at each recording date. Separate stems on single individuals have separate Key field method elements rows, but they are linked through code numbers. Further information, such as the number of indi- 1. Select plot positions or transect lines according to viduals of each species per plot, can also be entered pre-determined criteria. into a computer package. 2. Lay out plot approximately with ranging poles Thus, the changes over time of particular and pacing. attributes of individual trees can be displayed 3. Establish baseline, then lay out accurately with graphically and analysed statistically. Average tapes and adjust ranging poles. changes for particular plots, groups of trees or par- 4. Record with tapes in position. ticular species can also be calculated and analysed 5. Photograph from a position that is itself accu- to examine trends in the growth, regeneration, age rately recorded. structure, distribution and relative abundance of 6. Replace ranging poles with permanent markers. species. 6.5 Trees and woodland stands 229

Disadvantages Box 6.20 Permanent plots: likely problems and solutions * Extra work is required to mark and relocate plots and to store individual plot records. * The precise relocation of permanent plots is likely Changes within plots may be very slow; there is to be the most problematic aspect of monitoring a risk that over the timescales required to monitor by using this method. To ensure that plots can be changes, especially in well-developed climax relocated it is essential that plot markers be woodland, plot locations could be lost or even sturdy. It should also be borne in mind that destroyed. * permanent plots are vulnerable to vandalism; Changes within plots may not be representative of locate the markers out of harm’s way if possible. changes occurring at the whole woodland level, If fixed-point photographs are taken of the particularly if small numbers of plots are used. * markers, it may be possible to relocate plots even Maintaining long-term studies is notoriously pro- if the markers are destroyed. The fixed-point blematic and requires particular dedication. photographs will in any case be a useful part of Box 6.21 describes a case study of a method for a monitoring programme. monitoring tree regeneration and browsing damage See Part I,Sections2.3.2 and 3.4.2 for further by using permanent plots. discussion of the problems encountered with permanent plots. 6.5.3 Temporary plots

Likely problems with this technique, and their Recommended uses solutions, are summarised in Box 6.20. Temporary plots are plots that are marked out and recorded only once. They can be useful for providing a snapshot of the age structure and composition of a Summary of advantages and disadvantages wood for general survey purposes; for example, as Advantages releves for later classification such as the NVC * Relocation of plots allows precise measurements (Section 6.1.6). of change to be made down to the scale of indivi- For the purposes of monitoring change, enough dual trees. randomly distributed plots must be recorded on each * Any change observed is real (within the confines occasiontogivearepresentativesampleofthewood- of the plot and subject to measurement error), not land. A quantification of stand characteristics with estimated, and can be related to the performance standard errors can be made, which can be compared of individual trees. (by using statistical tests) with later surveys to see * If required, a large number of data on many whether any significant changes have occurred. One aspects of the distribution, condition and perfor- or two plots recorded as samples on surveys and not mance of trees can be collected. The amount of permanently marked will not be useful for monitor- data gathered can be tailored specifically to the ing change, because the error involved if data are needs of the monitoring programme. extrapolated over a larger area will be too large for * With sufficient numbers of plots, changes can be any meaningful conclusions to be drawn. statistically extrapolated to estimate changes that The method for recording temporary plots is the have occurred in the woodland as a whole. same as for permanent plots (Section 6.5.2). * Permanent plots can be recorded with fixed-point However, fewer data can be compared between sur- photography to provide an additional visual vey dates, because the progress of individual trees record of changes. cannot be tracked. It may, therefore, not be useful to * Surveys of other species (e.g. birds, lichens) can be record as much information on the characteristics related to the permanent plot. of individual trees as one does for permanent plots. 230 6 METHODS FOR SURVEYING HABITATS

Box 6.21 Case study: a method for monitoring every 5 years for conifer woodland and every 2 years tree regeneration and red deer damage using for broadleaved woodland. permanent plots RECORDING ALONG TRANSECT This method was developed by the ITE for monitoring woodland regeneration in areas in which deer grazing 1. Along the entire length of the transect a count is pressure was causing concern. It can easily be adapted made of all trees (of each species) between ground to other monitoring requirements. flora height and 3 m. The use of a 1 m or 2 m mea- The monitoring system is based on a series of suring pole is helpful for determining whether trees permanent 1000 m line transects incorporating five fall within the 2 m transect corridor, and whether 10 m 2 m quadrat sites at 200 m intervals. The lines small trees are above or below the surrounding are marked every 100 m with conspicuous markers. vegetation layer. String is tied between the marker At least one transect should be established for every posts to mark out the line. 2km2 of study area. The starts of transects should be 2. The state of the leader (largest tree) in each 100 m located at easily recognisable features such as bridges, section is recorded. track divides, etc. Each transect is 1000 m 2m 3. Sections of transect between quadrats are described oriented along a fixed arbitrary compass bearing. as (a) entirely open (no trees within 200 m), (b) Re-recording of established transects should be carried entirely wooded (>20 trees per 100 m2 per section) out within 2 weeks either side of the time of year when or (c) scattered trees (0–20 trees per 100 m2 per first recorded. Repeat recording should be carried out section).

100 m 200 m 10 m 2 m Transect start

6. Take four fixed-point photographs of each quadrat RECORDING QUADRATS at 908 intervals.

1. Mark the corners of each quadrat with marker pegs. String can be tied around these. TIME EFFICIENCY 2. Record the ground vegetation species or types No more than 5 minutes should be spent assessing where this occupies more than 25% of the quadrat. each quadrat unless there are difficult circumstances 3. Count all trees from emerging seedlings below vege- such as a large number of seedlings or difficult terrain. tation layer to 3 m in height. Normally a transect can be set up and recorded in 4. Record state of leading tree. half a day providing the ground is reasonable. 5. Count deer dropping groups. Source: Sykes et al. (1985).

One advantage of temporary plots, provided that Time efficiency a sufficient number are taken, is that a sample The time taken to record temporary plots them- representative of the entire wood can be taken selves will be similar to that needed for perma- each time. A permanent plot, although it provides nent plots (Section 6.5.2), although the time excellent data on changes within the plot itself, is taken overall will be generally less as there is no not necessarily representative of the woodland as a needtosetuppermanentmarkersatthestartof whole, especially if chance events affect the area the monitoring programme or relocate plots with containing a permanent plot more than elsewhere. precision on subsequent surveys. In addition, it is 6.5 Trees and woodland stands 231

Temporary plots: summary of key points Expertise required The ability to identify tree species in all seasons, and to assess their condition, is essential. Recommended uses Familiarity with transect and quadrat sampling methods and techniques is also necessary * Recording sample plots for surveys * Estimating changes in community structure and Equipment required Basic surveying equipment species distribution/abundance over large scales such as ranging poles and tape measures (see below for Efficiency Temporary plots should generally be details) quicker to record than permanent plots (see main text for details) Key methodological points to consider A sufficient number of plots must be taken to ensure that a Objectivity Good, as long as classifications (e.g. representative sample of woodland is obtained. The amount of canopy cover) and field methods are rigor- size and shape of plots will affect the type of change ously defined and adhered to that they are capable of monitoring; long transect belts Precision Good, providing measurements of tree will record grouping and zonation more clearly than location, height, etc. are accurate. Precision of small square plots estimates of change extrapolated over whole woodland will depend on the number of plots Data analysis Data can be held and processed using Bias Too few plots will give unreliable estimates a spreadsheet program. For analysis, a time series of of compositional and structural change occurring changes in single plots can be produced, or changes in through the whole woodland. Because trees are average plot composition, structure, etc. over time generally non-randomly distributed, biased estimates can be estimated and tested for statistical of relative density can be obtained significance likely that less information will be recorded on Data analysis temporary plots, though this may not necessarily Analysis of data is performed by using a spread- be the case. sheet program, as for permanent plots (Section 6.5.2). However, because the performance of individual trees is not measured, the analysis of change Expertise required over time is restricted to the comparisons of aver- Refer to Section 6.5.2. aged quantities such as height, girth, approximate age, etc., or changes in the average density, relative Equipment required abundance or other attributes of species. The equipment required for recording temporary plots is listed in Appendix 6. Summary of advantages and disadvantages Advantages Field methods * Temporary plots are quicker to locate and record The method for recording temporary plots is the than are permanent plots. same as for permanent plots. Refer to Section 6.5.2 * A sufficient number of randomly distributed plots for details. provides a representative sample for monitoring changes on the scale of the whole woodland. Data storage and analysis * The location of samples can be varied to ensure Data storage that they are always representative of the entire Refer to Section 6.5.2. woodland at the time of each survey. 232 6 METHODS FOR SURVEYING HABITATS

* The analysis and storage of data is quicker and There are several methods for estimating den- simpler than for permanent plots. sity, etc. by using plotless samples. These are described in Field methods below. Disadvantages

* Information on the progress of individual trees Time efficiency cannot be collected. Plotless sampling is generally a much faster method * If not enough plots are recorded, the results can- for estimating tree density (or other characteristics) not be used for monitoring changes and are not than quadrat or transect plots in woods, because the representative of the woodland as a whole. plots must be large to give a representative sample of the community (Bullock, 1996). 6.5.4 Plotless sampling The time necessary to record a suitable number of samples will also depend on the method of sam- Recommended uses pling chosen (see Field methods below). The point- Plotless sampling is a relatively quick method for centred quarter and T-square methods will take estimating density, average height, girth, canopy longer than the nearest-individual method. spread, etc. of trees. The method is most commonly used for estimating density, but any other informa- Expertise required tion that can be recorded about individual trees can Plotless sampling is not a specialist technique. be measured and averaged (see Section 6.5.2). Obviously, surveyors must be able to identify tree Repeating surveys and comparing the results species (including during winter if necessary) and with those of previous surveys gives an estimate be competent at making accurate measurements of changes in density, etc. over time. and recordings in the field. The use of a hypsometer

Plotless sampling: summary of key points Expertise required The ability to identify tree species and competence at field measurements and recording Recommended uses is necessary

* Estimating the density, height, girth, etc. of trees in Equipment required Little equipment necessary a woodland (tape measure, field recording equipment); see main * Estimating changes in these quantities text for details

Efficiency Generally a much faster method for Key methodological points to consider estimating attributes than using permanent or * temporary plots If measuring density of separate species, decide in advance which ones to look at: scarce species may be Objectivity Little room for subjectivity if method is time-consuming to study because the distance properly followed. Some subjectivity arises if deciding between individuals can be large not to include saplings; at what point does a sapling * The core area in which random points are become a tree? located should be smaller than the entire study Precision Depends on the particular method used area to allow for the possibility that the nearest and the number of samples taken individual trees to some points may lie outside Bias Serious bias can result if the distribution of the study area species is not random (either clumped or uniformly * Ensure that enough points are taken to allow a distributed). If different species have different spatial representative sample to be obtained distributions, a biased estimate of relative density will be obtained. This method does not select a totally Data analysis Generally very simple and quick to random sample of trees perform; see main text for details 6.5 Trees and woodland stands 233

D1 D2 D4 D D3 x y

Nearest-individual Point-centred quarter T-square sample

Figure 6.3. Plotless sampling methods. See text for details. or Abney level may be necessary if an accurate 1996). If there is considerable variation in the measure of height is desired. data it may be preferable to stratify the wood into reasonably distinct stands (see Sections 6.5.1 Equipment required and 2.3.3) and take separate sets of measurements Very little equipment is required for plotless sam- in each. pling (Appendix 6). Tape measures are necessary All methods involve the assumption that dis- for recording distance, girth, etc. A compass is use- tance is measured to the centre of the tree, which ful for the point-centred quarter method (see must be estimated. below) but not essential. A relascope can be used The methods are illustrated in Figure 6.1. to estimate mean basal area of trees at a given point (Horsfall & Kirby, 1985); whether or not this mea- Nearest-individual method surement is needed will depend on the monitoring The tree nearest to the sample point is located, and requirements being met. the distance between it and the sample point is Field methods measured. The density is calculated thus: A number of plotless sampling methods are possi- 2 Density ¼ 1=ð2DmÞ ble. The three most commonly used for trees are described here. where Dm = mean distance for all samples. These methods are generally used for estimating density. However, other information about Point-centred quarter method trees selected by using any plotless sampling Two perpendicular straight lines, which cross each method can also be recorded (e.g. height, girth, other at the sample point, are measured out, creat- condition, etc.). For details concerning the recording four quadrants centred on the sample point. ing of these observations refer to Section 6.5.2. The orientation of these lines should be the same The remainder of this section deals with estimat- for all points. A compass bearing can be used for ing density. this, or if a transect is being used to locate sample All the methods require the locating of a certain points, the transect line can be used for number of randomly selected sample points. If you orientation. are estimating density etc. for each species sepa- In each quadrant the distance to the nearest tree rately, the same set of points can be used for all is measured. These four distances are averaged, and species. This will be quicker than locating a differ- density is calculated thus: ent set of points for different species. The minimum number of sample points neces- 2 Density ¼ 1=Dm sary will depend on the variations in tree distribution, but at least 50 should be taken (Bullock, where Dm = mean of average distances. 234 6 METHODS FOR SURVEYING HABITATS

T-square sample method Density estimates and other information Because trees are rarely randomly distributed (they recorded can be compared between surveys on dif- tend to be either clumped, or if in plantations, ferent dates by using statistical tests to monitor regular), the above methods give biased results. changes over time as long as enough samples are T-square sampling overcomes some of this bias taken on each survey, the bias is not too severe and because it combines two methods (nearest- the direction of bias is understood. neighbour and point-to-object) that are biased in opposite directions. If species are aggregated, Summary of advantages and disadvantages nearest-neighbour overestimates density, whereas Advantages point-to-object underestimates it; if species are * Plotless sampling is generally a much faster regular the opposite is true (Greenwood, 1996). method than quadrats or transects. Therefore some of each bias will cancel the other * Little equipment is required. out. From each random point the distance (x) is measured to the nearest individual of each species in Disadvantages question. A line at right angles to the line from the * If species are at very low density it may take a long point to the tree is laid out, and the distance (y)is time to locate the nearest individual. measured from the tree to its nearest neighbour on * When surveying an area with high species diver- the opposite side of the line from the original sity, the time taken to measure separate species point. Density is calculated thus: will be greater. X X * The method contains inherent bias due to the non- Density ¼ n2=ð2:2828 x yÞ; random selection of trees even if trees are approximately randomly distributed. where n = number of points.

Data storage and analysis 6.5.5 Dead wood surveying and Data storage monitoring See Section 6.5.2. Recommended uses Data analysis Surveying and monitoring the amount of dead wood Density calculations are given in the field methods present in a woodland is a useful measure of habitat section (above). quality. Dead wood is a vital part of the woodland It is worth noting that the bias arising from the ecosystem, providing habitat and food for numer- non-random distribution of species has led some ous organisms including invertebrates and fungi. ecologists to state that plotless methods should Overmanaged woods may contain less dead not be used for estimating density. Even if trees wood than they should, because dead trees are are randomly distributed (which is unlikely), a sometimes removed. Monitoring the amount of random sample of trees is not obtained by using dead wood present is useful in this context. See plotless sampling, because the method ensures Section 5.1 for more details. that isolated trees are more likely to be sampled (Bullock, 1996). Time efficiency The T-square method is reasonably robust when This will depend upon the precise method chosen used on non-random distributions, but it is worth- for survey and the amount of dead wood present. while applying a test of randomness to the data in Once the method is understood, dead wood in a order that possible biases are not overlooked compartment can be quantified in 2.0–2.5 hours on (Greenwood, 1996). site and 1.0–1.5 hours of calculations. 6.5 Trees and woodland stands 235

Dead wood: summary of key points Bias Overgrown dead wood is easily overlooked, leading to an underestimation of dead wood content. Recommended uses Dead wood on living trees is difficult to measure

* Surveying and monitoring dead wood is useful for Expertise required No specialist expertise necessary assessing the habitat quality of a woodland, because Equipment required Basic woodland surveying dead wood provides niches for a wide variety of flora equipment and fauna Key methodological points to consider Efficiency Takes 2–4 hours to assess and analyse dead wood content in a compartment (see main text for * Dead wood is easily overlooked details) * For monitoring purposes, a statistically sufficient sample must be taken each time a survey is carried Objectivity As it is impracticable to include every out dead twig in a woodland, some arbitrary criteria for * Safety should be considered when monitoring dead exclusion must be applied wood, particularly if assessing dead branches above Precision Estimates of dead wood volume are based head height or whole standing dead trees on the assumption of cylindrical shape; this is an approximation, but is likely to be sufficiently accurate Data analysis Straightforward and reasonably quick for monitoring purposes to do; see main text for details

Monitoring is achieved by repeating the survey. Expertise required The volume of each piece can be calculated by Basic field recording and transect or quadrat map- assuming that it is a cylinder with the diameter of ping techniques are necessary. the mid-point. The time taken for each recording of each plot depends on the density of small pieces Equipment required of dead wood. The time taken to compute results is The equipment requirements for monitoring dead facilitated by a spreadsheet. Transect sections (see wood are summarised in Appendix 6. Section 6.5.3) can conveniently be used as plots. In this instance, the stand data can be related to the Field methods dead wood data. A convenient assay of dead wood Fallen wood can be mapped and measured in repre- can be achieved by measuring the diameter of all sentative plots. The plots should be at least 20 m pieces intersected by the boundaries between sec- wide. Select a convenient minimum size of dead tions of the transect. wood to be recorded: a useful convention is all An alternative approach, the line transect fallen stems attaining 1 m in length and 15 cm method, has been developed from techniques for mid-diameter (those smaller than this are hard to measuring logging waste. This is applicable to mea- find and only comprise a small proportion of the suring all forms of dead wood in a compartment. total volume). Each qualifying piece is then Within the area to be assessed, ten 25 m transects recorded by: are randomly located. Randomisation is achieved 1. approximately mapping by locating its end points by locating initial points regularly by pacing, then (for permanent plots); selecting a compass direction for the transect by 2. measuring its length and mid-girth (or diameter if using random numbers, ensuring that each trans- the log is partly buried); and ect stays within the area to be assessed. Fallen wood 3. recording degree of decay on a four- or five-point is assessed by measuring the diameter of all pieces scale. intersected by the tape marking the transect lines. 236 6 METHODS FOR SURVEYING HABITATS

quantity can be devised for each element, and the Box 6.22 Likely problems and solutions compartment being assessed can then be scored for each element. The sum of the indices gives a site The variation in size between large pieces of dead dead wood index, which can be calibrated against wood is high. These should probably be individually actual estimates of volume. Speed of assessment is counted rather than averaged to avoid large bought at the cost of accuracy. The method has yet amounts of variability in the data. to be fully developed. Repeat surveys will give data for comparison with earlier surveys to monitor changes in the Stumps and snags can be assessed by measuring amount and type of dead wood present. The stan- height and diameter of all those whose centres dard errors in this system may be large, so signifi- fall within 2 m of the transect line (i.e. within a cant measurements of change may be difficult to belt 4 m wide). Likewise, dead wood in living trees achieve (see Box 6.22). can be assessed in all trees whose centres stand within the 4 m wide belts. Formulae are available Summary of advantages and disadvantages for converting basic observations into length and Advantages volume per hectare. The principal difficulty lies in sampling the large logs, which are few, but impor- * Measuring dead wood content gives extra infor- tant, and easily missed. Logs above 20 cm diameter mation about habitat quality, which would other- may have to be individually assessed. wise not be recorded. This can be very useful when Rapid assessment of dead wood by using fixed- assessing the potential habitat for species that point photographs has proved to be impracticable. require some dead wood at some stage of their Even large logs can be lost in ground vegetation. life cycle.

Data storage and analysis Disadvantages Data storage See Section 6.5.2. * The standard errors in this method may be large, so significant measurements of change may be Data analysis difficult to achieve. Rapid assessment of the main dead wood elements * Dead wood is often easy to overlook, especially if at a compartment scale can be achieved by means overgrown by vegetation. This leads to biased of indices for each element. A five-point scale of results. 7 * Surveying and monitoring management or environmental impacts

As well as surveying and monitoring the condi- developments, will hopefully redress the balance tion of features of interest on a site, it is also in the coming years. often necessary to monitor the effects of manage- This section presents a summary of the management practices or environmental impacts. ment and environmental impacts that are most Management is usually carried out with the aim likely to be of concern when monitoring. An over- of achieving a particular target condition for a view of the issues involved and a brief discussion of feature; for example, grazing might be introduced the key features that should be monitored, to maintain the species richness of a grassland, together with some pointers for monitoring tech- or burning might be carried out to rejuvenate a niques, is given. References are provided should patch of moorland. It therefore follows that the any further details be required. impacts of management need to be monitored to Recreational impact monitoring is not covered, ensure that management practices are having the but a useful review of the monitoring of trampling desired effect. If management appears to be inef- impacts can be found in Legg (2000). fective or has adverse effects, then the management regime can be appropriately adjusted. Records of past management practices and 7.1 GRAZING AND BROWSING changes resulting from these are therefore vital 7.1.1 Background if interventionist site management is to be more than a hit or miss affair. Building up a body of Grazing and browsing are vital management knowledge on the effects of different levels of requirements for many habitats, including heath- grazing, burning, etc. on different habitats will lands, peatlands and grasslands. Grazing by domes- enable management regimes to be sensitively tic and wild animals can also influence the species designed. Monitoring non-management impacts composition and structure of most habitats. such as those caused by erosion or unplanned Different herbivores have different plant prefer- fires is also important. Erosion is a naturally ences, feeding habits and dunging habits. The plant occurring process in some habitats, but may preferences of grazing animals can profoundly also be caused or exacerbated by management affect vegetation structure and composition. practices. Surveying and monitoring the effects Stocking levels and seasonal grazing regimes have of, for example, developments such as ports, mar- further impacts on a site, as do the inter-relationships inas, airports, built development and associated between different herbivores that may be present infrastructure is now the norm, and yet few on one site, including domestic stock such as such studies exist to show the effects of such sheep and cattle and wild animals such as deer, environmental impacts. Standardisation of the rabbits and voles. When monitoring the impact methods of data collection, as provided in this of grazing it may be necessary, in some situa- Handbook, and an increased importance placed tions, to be able to assess the relative importance on the publication of results in association with of different grazers in determining the condition

# RPS Group plc and Scottish Natural Heritage 2005. 238 7 MANAGEMENT OR ENVIRONMENTAL IMPACTS

of the site. Supplementary feeding and shepherd- habitat attributes required by associated fauna (for ing influence ranging behaviour and hence affect example, heavy browsing of dwarf shrubs on moor- the site and might also need to be monitored. land edges and in the field layer of pine woods has considerable detrimental effects on Black Grouse 7.1.2 The effects of grazing and browsing Tetrao tetrix and Capercaillie Tetrao urogallus). Larger animals, such as cattle and Red Deer Cervus elaphus, Digestibility and palatability of plants are impor- can open up vegetation through trampling and cre- tant in determining the grazing influences of live- ate bare areas, which can act as regeneration sites stock. For example, areas of vegetation associated for plants. If this is particularly severe it can lead to with flushes, or areas of vegetation on calcareous soil erosion or the spread of undesirable species on pockets within a site, are often relatively more to the site. Dunging can affect nutrient cycling, attractive to grazing animals than are the sur- especially when it is concentrated in parts of a site, rounding habitats. Some species, particularly and again can cause problems if severe, for example many grasses, sedges and rushes, are more resis- through soil eutrophication. All of these elements tant to grazing than others, and therefore may need to be borne in mind when designing a mon- become more abundant in heavily grazed sites. itoring programme for a site. These factors, as well as the feeding preferences An important aspect of grazing and browsing of individual animals, can create a very varied pat- impacts, from the point of view of monitoring tern of vegetation throughout the whole site. design, is that they are always ‘patchy’ over a Considerable differences in species composition, range of spatial scales, and rarely constant vegetation structure and height, amount of open throughout the whole site. and bare ground, and degree of damage to trees and shrubs through bark stripping can occur. 7.1.3 Monitoring methods Undergrazing can allow rank grasses and unpalatable plants such as ragwort to spread (although Aerial photographs (Section 6.1.3) can be of use for under very low grazing pressure unpalatable plants the identification of historical changes in habitat may decline relative to competitive palatable spe- (e.g. the spread or decline of trees or heathland). cies, which are no longer held in check by grazing). These changes can sometimes be linked to altera- For example, the spread of trees and scrub onto tions in management regimes. If records of histor- heathland and grassland areas, particularly in low- ical grazing regimes are available, the information land regions, has been linked with the decline of gained from the study of past aerial photographs livestock grazing. It is also known that overgrazing could be used to predict the results of future of heathland can lead to the replacement of heather changes in grazing levels (although reversion to with grasses (Bardgett & Marsden,1992). Overgrazing previous grazing regimes does not always lead to can also lead to excessive poaching and weed inva- the recovery of the previous vegetation). However, sion. Excessive browsing can completely prevent it is very difficult to pick up from aerial photo- tree regeneration in woodlands. Patterns of damage graphs any subtle changes caused by grazing. to plants and the resulting growth responses can be The majority of the monitoring of grazing will distinctive and especially pronounced in trees and normally focus on grassland and heathland shrubs. These have been well described for heather: habitats. Tall herb communities, scrub (e.g. sub- ‘drumstick’ growth occurs when mature heather is Arctic willow scrub) and flushes can also be very overgrazed, and ‘topiary’ growth (domed bushes) sensitive to grazing and are likely to require mon- occurs when building-phase heather is overgrazed itoring in respect of this if they are features of (MacDonald et .a,199 l 8a,b). interest on a site. The monitoring of wild grazing The effects of grazing animals are, however, not animals such as deer may also be very important limited to the direct effects of grazing on the plants in woodland and scrub habitats. In general, esti- themselves; they can also be very important for mates of vegetation height, plant species richness, 7.1 Grazing and browsing 239

cover or frequency collected by using quadrats SNH guide to surveying land management (Sections 6.4.2–6.4.5) or transects (Section 6.4.6) impacts in upland habitats (MacDonald et al., will be sufficient for most monitoring purposes. 1998a,b) Vegetation height is a useful measurement of Assessments are made of the condition of vegeta- grazing intensity and is often under-recorded, tion and ground features to determine whether even though it can be an important factor (for land is heavily, moderately or lightly grazed. You example, sward height of grazed grasslands can should look for direct evidence of grazing impacts be of particular importance for the success of and base assessments only on this evidence, relying some butterfly species). Additional information as little as possible on supposition (although you on vegetation structure and amount of bare ground can use well-established knowledge of animal may also be of interest and should be collected if behaviour and ecological processes in order to deemed necessary. interpret this evidence). Depending on the reasons for monitoring, a A detailed guide to the assessment method has number of aspects of grazing and associated land been developed, which cannot be described here. management activities may need to be noted. However, the following features should be recorded: These may include:

* stocking rates and grazing periods; Effects on soil: * supplementary feeding; * amount of bare ground, including trampled bare * type of stock and breed; peat and sparseness of the vegetation; * timing and rates of applications such as farmyard * bare peat exposed by trampling, wallowing and manure or lime; rubbing by livestock and wild animals; * details of rolling, chain harrowing and burning; * percentage of poached ground; * numbers and species of wild grazing and brows- * amount of dung deposited by different species of ing animals; and grazing animals; and * control of pest species such as Rabbits Oryctolagus * extent of sheep, deer or cattle paths. cuniculus and weeds such as Ragwort Senecio jacobaea. Effects on vegetation composition It is probably best to record this information sepa- and community structure: rately from any assessment of grazing impacts to avoid the possibility of biasing an observer’s * sward height and structure; assessment. * sward height of dwarf shrubs in associated grass An additional piece of information that can be patches; * useful is the pattern of use of the ground by stock. presence of seedlings and saplings above a certain However, this information can be extremely time- height; * consuming to obtain, and involves a number of site presence of ‘weedy’ species in dense extensive visits at different times of day and on different patches; days. A simpler way of obtaining this information * patches of taller vegetation, including tall herbs, is from the assessment of impacts on the vegeta- ferns or tussocky grass; and tion and/or patterns of dung distribution. * cover and frequency of small, rosette-forming, Approaches to monitoring grazing have been creeping or mat-forming herbs. developed by MacDonald et al.(1998a,b) for SNH Effects on plant growth and reproduction: and by English Nature (1995). Although the former only covers upland habitats, the principles can be * the presence of topiary growth forms caused by the applied to lowland situations. The latter covers close grazing or browsing of saplings and bushes; heather moorland. These two methods are * browsing of seedlings or saplings; described below. * evidence of bark stripping; 240 7 MANAGEMENT OR ENVIRONMENTAL IMPACTS

* uprooted bundles of grass tillers; each of the component blocks, which is then com- * disruption of moss and liverwort carpets; pared to a graduated scale, which in turn indicates * accumulation of dead plant litter in the sward; the intensity of grazing. * amount of flowering of indicator species (e.g. cot- Although relatively simple, the grazing index ton grass); method has a number of limitations. First, it relies * signs of grazing on indicator species; and on only a relatively small number of grazing indi- * degree of flowering and vegetative state of poten- cators. Second, no distinction is made between past tially taller herbs. and current grazing intensity; some sites will have become grass-dominated a long time ago and have Additional information on features such as the little prospect of reverting to heather in the fore- form of clipping of plants, the characteristics of seeable future even if current grazing pressure is severed shoots, and the height at which most low. Third, the percentage of grass to heather is signs of grazing or browsing occur can suggest used as an indicator, but very recent heavy grazing which animals may be having the most impact. may cause a significant detrimental impact on heather without immediately having much effect Grazing index (English Nature, 1995) on the heather–grass balance. Finally, the grazing The grazing index is a systematic and easy method index is an average, which can be misleading as of assessing the vegetation condition of heather heather areas often shrink from the edge where moorland. It provides a rapid field assessment of grazing is high, whereas grazing intensity in the the grazing level on a moorland and indicates if the centre of heather stands is much lower. Such area is likely to be under threat from heavy grazing averages are of limited use unless the grazing pres- pressure. sure is extremely high, as it is in many parts of The heather moorland is divided into blocks of England and Wales. In regions or habitats where 10–50 ha; within each of these blocks an assess- grazing levels are generally low the use of the graz- ment is made by scoring three vegetation indica- ing index is not recommended. tors while walking the land. Little botanical knowledge is required and a 50 ha block can be assessed in under 2 hours. 7.2 BURNING A ‘W’ or representative walk is conducted across 7.2.1 Background the whole of the ‘index unit’ to make an assessment of the percentage of grasses and dwarf Burning is practised frequently and widely over shrubs, and to identify the area of heather to be a wide range of vegetation types. It is most com- assessed at the next stage. Once the areas of monly employed as a management technique in heather have been identified, another ‘W’ or repre- the uplands, mainly for the maintenance of grouse sentative walk is made. This time, an assessment is moors. The burning of heather stimulates new made within each quadrat (size can be between growth and rejuvenates the heather sward, 25 Â 25 m2 and 2 Â 2m2) of the percentage cover although if large areas are burned it will result of Calluna vulgaris and other ericoid shrubs. While in the loss of age-structure diversity. Burning is walking this heather area, the surveyor also also widely practised on sheep walks and deer assesses the age structure and growth forms of forest. heather. Guidance should be given on the recogni- Burning is also employed to improve the grazing tion of features that indicate heavy grazing (e.g. quality of hill land by stimulating a new flush of lack of regenerating heather, or drumstick and grass growth, and can also be used to bring rough topiary growth forms). grassland back into condition before the reintro- A score is calculated for each block of heathland duction of grazing. Unplanned fires often occur in a surveyed (see English Nature (1995) for details). The range of habitats, but dwarf-shrub heathlands are grazing index score is the sum of the scores for particularly vulnerable. 7.2 Burning 241

extent more straightforward. The features to be 7.2.2 The impact of burning monitored listed below are taken from the method The degree of the impact caused by burning will developed by MacDonald et al.(1998a,b) for SNH. depend on a number of factors but it is primarily Although this guide specifically covers uplands, influenced by the amount and distribution of fuel most of the principles also apply to the lowland material on the site and weather conditions at the situation. time of the fire. This is influenced by the habitat Although the sampling techniques described are type, vegetation composition and structure, and not principally designed for monitoring, the indi- also by the current management regime operating cators of burn intensity can form a measurement on the site. basis for quantitative monitoring if used in con- The impact of the fire will be further influenced junction with quadrats (Section 6.4.2) or transects by the amount of moisture present in the surface (Section 6.4.6). Photographs can also be used to layers of soil or peat, the wetness of the vegetation make methods more repeatable. The impact assess- and the amount of litter on the site. Fire impact is ment methods described are relatively quick to also affected by the ability of species either to avoid undertake but some are not tightly defined. Some fire damage or to recover from it. Resilience to judgement is required, and this makes the assess- burning varies between species and according to ment more difficult to repeat exactly. the age and size of the plant. Flowering and seed It is important to note that information on other production of some plant species is often enhanced management activities that may also occur on the after burning, which can help to promote rapid site following a burn will also need to be collected, recovery through the establishment of seedlings especially grazing regimes, mowing cycles and even if vegetative recovery is slow. Burning can pollution. These activities will considerably affect also remove the litter layer and thereby create the recovery of vegetation and will possibly influ- gaps, which offer further opportunities for the ence decisions taken on the future management of establishment of new plants. the site. Monitoring of intentional, accidental and ‘wild’ fires should be carried out to determine: Monitoring the geographical extent of burns The best method for measuring the extent of a * the geographical extent and intensity of burns, burn, particularly large-scale burns, is the use of and to evaluate the immediate effect of a fire on aerial photographs (Section 6.1.3). However, these vegetation and ground condition, particularly will usually have to be specially obtained for this peat and litter; purpose as soon as possible after the burn, thus * the recovery of vegetation following a burn; increasing the costs of monitoring. Burns on * the cumulative impacts of repeated fires; and dwarf-shrub-dominated heathland should be dis- * beneficial changes to future management prac- cernible on aerial photographs for at least 5 years. tices (e.g. the identification of suitable areas of Existing aerial photographs can be helpful in mature vegetation that might be protected from identifying the extent of past burns. This will burning, or the identification of areas that might enable the impacts of fires over a longer time per- benefit from regular burning). iod to be examined. Fixed-point photography (Section 6.1.4) can also be used, although markers 7.2.3 Monitoring methods will have to be selected after a burn has occurred and will not therefore yield any data on the effects Monitoring requirements will vary from site to site; of the fire. most of the techniques for monitoring of vegeta- Simply walking across the site to record impacts tion changes have already been described in pre- will yield useful information, and will probably be vious sections. Fires often have sharply defined required in any case to record additional informa- boundaries, which can make the monitoring of tion other than the extent of burns. This is best 242 7 MANAGEMENT OR ENVIRONMENTAL IMPACTS

undertaken with annotated aerial photographs to also be used to monitor the impact of fire on other aid orientation and accurate mapping, and needs to habitats. be systematic if the impact on the entire site is to be described. Monitoring the recovery of vegetation following In heath vegetation with a high proportion of a burn graminoids (especially Purple Moor-grass Molinia This is best achieved through the use of quadrats caerulea) it can be very difficult to identify burnt (Section 6.4.2) or transects (Section 6.4.6). Changes areas on aerial photographs after the year in in cover of plant species or groups should be which the fire occurs. There is much less contrast recorded at regular intervals to examine the in colour and structure between burnt patches and changes that take place before and after a burn. the surrounding area than there is in vegetation Alternatively, presence–absence or frequency of dominated by heather. This is because Molinia key species can be recorded in the same way. regenerates rapidly after burning; burnt areas in Bryophytes and lichens can be important groups this type of vegetation can be hard to identify to record; for example, the recovery of Sphagnum even from the ground. mosses is particularly important in bog and other Fires can also be hard to identify on aerial photo- mire habitats. Other important indicators of the graphs where they have burned in an irregular speed of recovery of vegetation are the amount of pattern (light and/or fast-moving fires often burn bare ground present after the burn and the speed at patchily) or have burned through patchy vegeta- which it is colonised by plants. tion. However, these fires can usually be readily If permanent plots are used for monitoring, then identified on the ground for several years after the use of metal posts or buried markers is recom- they occur. mended, as wooden posts can easily be lost if To determine burn intensity and evaluate the further fires occur at the site. A range of burned immediate effects of a fire on vegetation and areas may need to be examined to cover the variety ground condition, the following checklist gives of impacts caused by variation in fire intensity, some of the main factors that need to be recorded vegetation type, soil type, etc. to categorise the intensity and frequency of burns Particular features that may be worth recording (adapted from MacDonald et al. (1998a,b)): include:

* pattern of fire advance; * pattern of colonisation and regrowth after * colour of burnt patches immediately after burning; burning; * occurrence of indicator species (normally lichens * extent of bare peat, erosion and exposed mineral and mosses) that appear after a burn; soils; * amount of regeneration, and whether this occurs * degree of combustion or ‘cooking’ of the surface from seed or from sprouting stems; and upper layers of peat; * extent, diversity and luxuriance of mosses, includ- * solidity and texture of the upper peat layers; ing Sphagnum mosses; * amount of ash, and amount and size of charcoal * relative structural dominance of dwarf shrubs fragments, immediately after burning; compared with certain grasses; * damage and degree of combustion of loose moss * abundance of certain grasses and vascular plants; mats, lichens, plant litter, grass tussocks and * abundance and luxuriance of certain Cladonia woody material; lichens; * effects of fire on any bushes and trees; and * relative abundance of different dwarf-shrub * survival of clubmosses and ferns. species; These points mostly relate to blanket bog and * abundance of dwarf-shrub seedlings in years after upland heath, where burning is most frequently burning; and encountered. However, some of these features can * average density of vascular plant species. 7.3 Erosion 243

can be threatened. Structures such as paths and 7.3 EROSION tracks, stock fences and interpretative features 7.3.1 Background can all be swept away or undermined. However, some species rely on ground distur- Erosion can occur on a wide range of scales, from bance for survival and cannot persist in more stable localised bank erosion caused by cattle poaching or habitats. Some species of conservation concern can stream flow to the large-scale loss of vegetation and therefore benefit from certain erosion events (for topsoil resulting in the loss of large areas of habitat. example, many plant species in the East Anglian Peat soils, in particular, can be particularly sus- Brecklands are dependent on vegetation distur- ceptible to erosion once their protective vegetative bance by intensive rabbit burrowing or rotavation cover is removed. Consequently erosion is most to keep their ecological niches open). widespread, and is often most severe, on blanket The monitoring of erosion should therefore be bog habitats (Section 5.12). Some types of friable carried out to: upland soils found on a number of mountains in north-west Scotland are also very vulnerable to * monitor the spread of the problem, or the degree erosion once the overlying vegetation mat is of stabilisation, so that appropriate action can be disrupted. taken (e.g. the construction of stabilisation Erosion can also occur on steep slopes if the structures); underlying substrate is susceptible (e.g. very friable * determine the rate of vegetation recovery so that soils with low shear strength, on account of a low any further work that may be required can be clay content). Exceptional weather conditions, identified (e.g. vegetation establishment); such as heavy rainstorms, can produce unusually * identify possible future threats to adjacent habi- high hydrological loading of the soil, which further tats and species; and weakens its cohesion. Heavy grazing, trampling, * identify dangerous areas where access by mem- and frequent or high-intensity burning may further bers of the public and others may need to be weaken and destabilise the soil. This type of ero- restricted. sion most commonly occurs on valley sides and cliff faces. Poor drainage can be another cause of erosion. Gullying can be caused by artificial drains 7.3.3 Monitoring methods if they lead into, and overload, an existing water This is best achieved by referring to some of the track. methods outlined in Chapter 6. Aerial (Section Sand dune habitats are also susceptible to ero- 6.1.3) and fixed-point (Section 6.1.4) photography sion, but dunes are naturally dynamic, particularly can be particularly useful for delimiting areas in the earlier stages of dune succession, so erosion affected by erosion in the first instance and for is not inherently a problem. Problems with erosion monitoring the spread or stabilisation of eroding on sand dunes tend to be correlated with areas areas over time. subject to high visitor pressure. For more precise recording of the speed of erosion it may be worth considering placing markers 7.3.2 The impacts of erosion along some or all of the erosion fronts. At the most basic level, these can be simple wooden posts At its most destructive, erosion can cause the loss spaced at regular intervals, but more sophisticated of not just vegetation but entire soil profiles and calibrated measuring devices can be used to mea- rock faces. Following the initial onset of erosion, sure loss of soil or peat from the ground surface. the affected area can increase in size substantially Problems can arise, however, if the substrate is in until a natural equilibrium is reached or manage- danger of further erosion or slippage, and the poten- ment is undertaken to stabilise the erosion. Whole tial dangers of firstly placing the markers and sub- vegetation communities can disappear and species sequently reading them should be borne in mind. 244 7 MANAGEMENT OR ENVIRONMENTAL IMPACTS

The risks may be potentially too great for monitor- and during it to prevent encroachment of the ing erosion from the ground, particularly on steep development footprint and construction activ- slopes. Binoculars may be useful to take measure- ities into areas of habitat identified by the ES as ments from calibrated markers at a safe distance. being of conservation or ecological interest (with Another monitoring method that is normally habitat evaluated at local, regional, national and worth considering is the recording of vegetation international scales); recovery on eroded ground. This is most frequently (b) survey particular areas prior to the writing and undertaken through the use of quadrats (Section implementing of a plan for the translocation of 6.4.2) or transects (Section 6.4.6), although this can specific species, communities or habitats of also be dangerous in certain circumstances and noted value; should not be attempted on dangerous terrain. If (c) provide data on successive changes in habitat the eroded ground is stable enough for work to be areas and condition during the course of carried out safely, cover estimates or presence– development; absence of certain species can be made (see (d) monitor habitat areas and condition for a period Sections 6.4.2 and 6.4.3) to gain some idea of the after construction; speed of vegetation recovery and the successional (e) monitor habitat mitigation and/or creation. relationships between the plant communities that It is usual for such survey and monitoring work to colonise the disturbed areas. be made a ‘planning condition’ associated with a planning permission, often being legally binding 7.4 VEGETATION SURVEYS IN RELATION through a Section106 Agreement or Unilateral TO DEVELOPMENTS Undertaking. The majority of the survey work outlined in (a–e) There are a number of reasons why vegetation sur- above takes the form of a map of the habitats, com- veys are required in relation to development pro- munities or specific target species on the site and posals as part of the planning and development any off-site areas to which impacts from the devel- control process. Most development proposals that opment may be exported through, for example, have the potential to affect habitats, either volun- habitat fragmentation, diffuse pollution, dust, etc. tarily or as a planning application requirement An extended Phase I survey with target notes and under domestic or European conservation legisla- condition assessment would be the usual approach tion, will need a vegetation survey. The survey is for development related impact assessment. In normally included as part of an ecology chapter addition, it may be necessary and appropriate to of the Environmental Statement (ES) or measure vegetation attributes such as cover, Environmental Impact Assessment (EIA). If the height, soil moisture, etc., as a development pro- planning application for the development is suc- gresses in order to determine whether pervasive cessful there will then often be the need to: impacts are taking place. The relevant chapters (a) survey the development site (and off-site areas if and sections of the Handbook should be consulted potential off-site impacts have been identified at for the specific objectives and focus of the impact the ES survey stage), prior to the development assessment work. 8 * Habitat conservation evaluation criteria

8.1 KEY EVALUATION CONSIDERATIONS interpreted in terms of the NVC classification; the definitions of priority habitats for conservation in The conservation importance of habitats occurring the UK also use this system. in the UK has generally been assessed in terms of the Habitats can often be of value to particular spe- threat status of each habitat type, where attributes cies, rare or otherwise, for example because an area such as rarity and rate of decline (of overall area) have of habitat supports a viable population of the spe- been taken into account. In terms of evaluating the cies. However, this chapter is concerned with the conservation importance of any particular habitat intrinsic value of habitat types, rather than with type, reference must be made to international and their value for species. national conservation legislation and initiatives such as the UK Biodiversity Action Plan (UK BAP) process, described further below. 8.2 PROTECTION STATUS IN THE UK The key considerations with regards to evaluat- AND EU ing habitats are listed below. With regards to the protection of habitats, the fol- 1. Check lists of habitats of conservation importance lowing legislation is relevant: (see below for information on which lists to check * EU Directive 92/43/EEC on the Conservation of and where to obtain the relevant information). Natural Habitats and of Wild Flora and Fauna 2. Check existing designation status: for EIAs (see (the Habitats Directive); Box 8.1), the search area should extend to 2 km * Wildlife & Countryside Act 1981; from the boundary of the site. This will inform the * Countryside & Rights of Way Act 2000 (Section 74); results of the Phase 1 survey and highlight areas and of habitat on or near the site that are within * Nature Conservation (Scotland) Act 2004. the boundaries of statutory or non-statutory designations. The criteria for listing habitats on Annex I of the 3. Carry out a preliminary (scoping) survey for habit- EU Habitats Directive are summarised in Part I of ats. This will normally be a Phase I habitat survey this Handbook, as are the site designation criteria (see Section 6.1.5) to identify the broad forhabitat SACs. The full text of the Habitats Directive can types present on site. be viewed on www.ecnc.nl/doc/europe/legislat/ habidire.html, which gives the list of Annex I habit- These three steps should enable the determination ats. Similarly, the rationale for the selection of of Valuable Ecosystem Components (VECs) (in SSSIs under the Wildlife & Countryside Act (1981, terms of habitat types) that may potentially be pre- as amended) is also relevant; the Guidelines for the sent. To establish the actual presence or absence Selection of Biological SSSIs can be viewed on the of a VEC, further survey may be necessary; for JNCC website at www.jncc.gov.uk/Publications/ habitats, a National Vegetation Classification sssi/sssi_content.htm. (NVC) survey (Rodwell, 1991) is recommended. Section 74 of the CROW Act requires the Habitats listed in European legislation have been Secretary of State for England and the National

# RPS Group plc and Scottish Natural Heritage 2005. 246 8 HABITAT CONSERVATION EVALUATION CRITERIA

Assembly for Wales to each publish a list of species therefore viability) of areas of habitat when and habitat types that are of principal importance attempting to rank examples of different habitat for the conservation of biological diversity in types against each other. Box 8.2 provides a real England and Wales, respectively. The Section 74 example of the use of Ratcliffe criteria to assess a list for England can be viewed on the DEFRA range of vegetation types as part of an EIA. webpage www.defra.gov.uk/wildlife-countryside/ Habitats found on a site should be evaluated in cl/habitats/habitats-list.pdf. The equivalent list for relation to the habitat types listed on Annex 1 of Wales can be viewed on the National Assembly the EU Habitats Directive and the UK BAP for Wales website on the following webpage: (Section 74) Priority Habitats lists. Local biodiver- www.wales.gov.uk/subienvironment/content/gui- sity partnerships may also have published, through dance/species-statement-e.htm. the production of local BAPs, lists of habitats of These two lists are based on UK Biodiversity local conservation importance that, if available, Action Plan (UK BAP) Priority Habitats and Species should also be used for evaluation purposes. lists. In England, the list of Section 74 Habitats con- Guidelines for the selection of sites of conservation sists of the full list of UK BAP Priority Habitats importance at a County level may also be available with two additions (‘Lowland Mixed Deciduous from the Local Authority or Wildlife Trust. Woodland’ and ‘Upland Birch Woodland’). In Habitat types found on a site that are listed as Wales, the list of Section 74 Habitats comprises the habitats of conservation importance will generally UK BAP Priority Habitats list with the same two rank higher than types that are not, and habitats of additions (‘Lowland Mixed Deciduous Woodland’ international conservation concern will rank and ‘Upland Birch Woodland’) but also seven dele- higher than those of national concern or local con- tions (reflecting the fact these habitat types do cern. However, a small patch of an otherwise not occur in Wales): ‘Chalk Rivers’, ‘Upland Hay nationally or internationally important habitat Meadows’, Littoral and Sublittoral Chalk’, ‘Lophelia type may not be a viable area of habitat, and as pertusa Reefs’, ‘Serpulid Reefs’, ‘Machair’ and ‘Native such may rank lower than a large, ecologically Pine Woodlands’. There is currently no equivalent viable area of a locally important habitat type. legislation for other countries within the UK. Reference should also be made to the Ratcliffe criteria (size, diversity, naturalness, rarity, fragility 8.3 CONSERVATION STATUS IN THE UK and typicalness as primary criteria, and recorded history, position in an ecological/geographical The evaluation of Valued Ecosystem Components unit, potential value and intrinsic value as second- (VECs) (both habitats and species) for EIAs should ary criteria) when considering the value of areas of ideally follow the approach outlined in Part I of this habitat. Handbook, based on IEEM guidelines (2002), which Habitat types to be valued as being of international recommend grading the importance of sites or importance include: components thereof against the following levels of value: * An internationally designated site or candidate site (SAC, cSAC, etc); 1. International; * A viable area of a habitat type listed in Annex I of 2. National; the Habitats Directive, or a smaller area of such 3. Regional; habitat which is essential to maintain the viability 4. County/Metropolitan; of a larger whole. 5. District/Borough; 6. Parish/Neighbourhood. Habitats of national value include:

The generic evaluation section in Part I provides * A nationally designated site (SSSI, ASSI, NNR etc) examples, at each level of value for both habitats or a discrete area, which the country conservation and species, which take into account the size (and agency has determined meets the published 8.3 Conservation status in the UK 247

selection criteria for national designation, irre- Habitats of parish/neighbourhood value include spective of whether or not it has yet been notified; areas of habitats considered to appreciably enrich * A viable area of a priority habitat identified in the habitat resource within the context of the par- the UK BAP (or Section 74 for England or Wales), ish or neighbourhood, such as species-rich hedge- or of smaller areas of such habitat which are rows. Note that species-rich hedgerows may come essential to maintain the viability of a larger under the Hedgerow Regulations, requiring their whole. removal to be approved through the planning process. Habitats deemed to be of regional importance Unlike for species, the above list does not men- would include the following: tion the IUCN Red Data Books. Part I of this * Viable areas of key habitat identified in the Handbook provides an overview of the programme Regional BAP or smaller areas of such habitat for species, which are assessed in terms of their which are essential to maintain the viability of a threat status. Currently, there is no direct equiva- larger whole; lent for habitats. However, the feasibility of a Red * Viable areas of key habitat identified as being of Data Book for NVC vegetation types is currently Regional value in the appropriate Natural Area being researched, with the aim of providing infor- profile; mation on the rarity or otherwise of different NVC * Sites which exceed the County-level designations communities. In the meantime, the NVC books but fall short of SSSI selection guidelines, where themselves (Rodwellet .,a l1991 et seq.) can be con- these occur. sulted as a guide to the extent of different communities. However, the ‘distribution maps’ associated Habitats of county/metropolitan importance with each community are very incomplete and the include: text gives a better guide. For example, compare the * Semi-natural ancient woodland greater than distribution map for U20 (Pteridium aquilinum – 0.25 ha; Galium saxatile) on page 498 of NVC Volume 3 * County/metropolitan sites and other sites that the (Grasslands and Montane Communities) with the designating authority has determined meet the text on the distribution of the community on published criteria for designation, including page 495. The SSSI selection guidelines also give Local Nature Reserves selected on county/metro- an indication of the rarity of different NVC commu- politan criteria (these will often have been identi- nities, stipulating in some cases that all occur- fied in local plans); rences of a particular community type are eligible * A viable area of a habitat type identified in a for SSSI selection, for example S24 Phragmites county BAP. australis – Peucedanum palustre fen. Areas of habitat with district/borough importance Using Annex I of the EU Habitats Directive for include the following examples: habitat evaluation * Semi-natural ancient woodland smaller than In the UK, these habitat types have been inter- 0.25 ha; preted in terms of the National Vegetation * Areas of habitat identified in a sub-county (dis- Classification (NVC) (Rodwell 1991 et seq). The trict/borough) BAP or in the relevant EN Natural JNCC Report by Jackson & McLeod (2002), provides Area profile; an overview of current knowledge on aspects of the * District sites that the designating authority has conservation status in the UK of habitats (in terms determined meet the published criteria for desig- of range and extent) and species (in terms of dis- nation, including Local Nature Reserves selected tribution and estimated population size) that are on district/borough criteria; listed on Annex I and II of the EU Habitats Directive. * A diverse and/or ecologically valuable hedgerow For habitats, it also provides guidelines on the rela- network. tionship between NVC types and Annex I habitat 248 8 HABITAT CONSERVATION EVALUATION CRITERIA

types. This report is also currently available on Habitats, an NVC survey will be needed to deter- the JNCC website: www.jncc.gov.uk/Publications/ mine the presence or absence of a particular UK JNCC312/default.htm. BAP Priority Habitat type. The JNCC has recently As noted above, in order to fully evaluate the published an updated version of its ‘Phase I Habitat habitat types found on a site in relation to the EU Survey’ methodology, which includes an appendix Habitats Directive, an NVC survey is required. giving the relationship between Phase I habitat Therefore, if the Phase I habitat survey carried out categories and NVC communities ( JNCC, 1993). as part of a scoping survey for a site suggests that an This may help in the assessment of habitats against Annex I habitat may be present, an NVC survey UK BAP and Annex I lists. should be conducted as part of the evaluation, to The criteria used to list UK BAP Priority Habitats determine the presence or absence of habitats of can be found in Part I of this Handbook. A full list of European conservation importance. For example, a UK BAP Priority Habitats is provided in Appendix 2. Phase I survey may show the presence of Wet The list of UK BAP Broad and Priority Habitats can Dwarf Shrub Heath on a site situated on the north be found at www.ukbap.org.uk/habitats.htm. Cornwall coast. This heathland may be one of the NVC community types M14, M15, M16 or H5, in Using the local BAP process to evaluate habitats which case the heathland may be the EU habitat The local BAP process was developed as part of the type ‘Temperate Atlantic wet heaths with Erica UK BAP to implement habitat and species action ciliaris and Erica tetralix’. plans at a local level. In addition to setting targets for the implementation of action plans for UK BAP Using the UK BAP Priority Habitats (Section 74 Priority Habitats, many local BAP groups have listed Habitats) for evaluating habitats and produced action plans for habitats deemed to be The UK BAP Priority Habitats list, from which the of conservation importance at a local level. These Section 74 habitat lists for England and Wales are lists, if available, should be used to evaluate habitat derived, are defined within a wider framework of types that do not fall within the national or interna- Broad Habitat types that are largely comparable tional levels of value, as illustrated above. However, with the Phase I Survey habitat categories (NCC, it must be noted that at the local level, habitats are 1990a,b ). Within each Broad Habitat type areoften one included in local BAPs on the basis of their or more Priority Habitat types (i.e. habitats of UK value for species, rather than their intrinsic value. conservation importance), some of which are For example, the Merthyr Tydfil Biodiversity Action extensively defined and some of which are very Plan (South Wales) includes an action plan for narrowly defined. For example, ‘Lowland Coniferous Woodland because it often supports Calcareous Grassland’ is classified as the first nine important populations of Crossbill Loxia curvirostra, calcareous grassland NVC communities (CG1 – Nightjar Caprimulgus europaeus, Siskin and various CG9) and in essence includes all types of calcareous birds of prey such as Goshawk Accipiter gentilis,each grassland that occur in the lowlands. In contrast, of which has a particular level of conservation ‘Upland Hay Meadows’ comprises the single NVC significance in the UK. community MG3 Anthoxanthum odoratum – Geranium The definitions of these local habitat types are sylvaticum grassland. As such, UK BAP Broad and usually based on the UK BAP Broad Habitat types. Priority Habitats can often be identified through a As such, a Phase I Habitat Survey should identify Phase I Survey. However, for some Priority the presence of these habitats on a site. 8.3 Conservation status in the UK 249

Box 8.1 Suggested methodology for checking 6. Under Step 2, select (for example) ‘Grid Ref’ and existing designations enter the grid reference for the site in question, then click on ‘Open Map’. The MAGIC project (Multi-Agency Geographical 7. Wait for the map to load: this may take a while Information for the Countryside) is a one-stop shop for depending on how many layers have been selected. rural and countryside information from the partner 8. Information about the various layers can be found organisations (e.g. conservation agencies). It brings by clicking on the ‘i’ symbol at the top of the map, together definitive rural designation boundaries and selecting the layer required and then clicking on the information about rural land-based schemes into one feature on the map. For example, the name of a SSSI place and can be used as the starting point for checking can be obtained by selecting ‘Sites of Special the presence or absence of statutory sites of nature Scientific Interest’ and clicking within the SSSI conservation interest. The website (http://www. boundary shown on the interactive map. magic.gov.uk/) can provide information about statu- When carrying out an evaluation for an EIA, statutory tory designations on or near a particular site, as well as designations within 2 km of the site boundary should other countryside information, such as English Nature be considered. SSSI citations can be obtained from the Natural Areas. country agencies (for some agencies, this information Currently, the procedure for obtaining information is available on their website). By clicking on ‘Protected pertaining to a particular site is as follows (from the Sites’ on the JNCC website (http://www.jncc.gov.uk/), MAGIC website homepage). further information about international designations 1. Click on ‘Site Map’. such as SACs can similarly be obtained. 2. Click on ‘Interactive Map’. Non-statutory designations, such as County Wildlife 3. Under Step 1, highlight ‘Design my own topic’. Sites (CWS, also known as Sites of Interest for Nature 4. Tick layers to be viewed: these should include all Conservation, SINC, and Sites of Nature Conservation statutory designations at a minimum: National Interest, SNCI) are not currently available online. Nature Reserves, National Parks (including provi- Therefore the local Wildlife Trust will need to be sional), Ramsar Sites (for birds), Sites of Special consulted regarding the presence or absence of local Scientific Interest, Special Areas of Conservation wildlife sites on or near a site (up to 2 km from the site and Special Protection Areas (for birds). Other layers boundary for EIAs). The local Trust should also be able may be useful for the evaluation of particular to provide the criteria for selecting local wildlife sites species or groups of species, for example RSPB and the reasons for selecting individual sites. Once Reserves. again, this information will inform the evaluation of 5. When the layers have been selected, click on ‘Save the importance of various habitat types in a local Selection, then ‘Done’. context. 250 8 HABITAT CONSERVATION EVALUATION CRITERIA

Box8.2Examplesofassessmentofvegetation They have usually not been sprayed with herbicide, types and they receive either little or no fertiliser. They are usually cut for hay, and are ungrazed in summer but The following examples, modified from a real mayEIA, be grazed in winter (Rodwellet .,a l1991 et seq.). show how the Ratcliffe criteria can be used toThey place are still locally frequent nationally but have vegetation and habitats in context. declined dramatically owing to agricultural The meadows present in the EIA study areaintensif wereication. assessed for nature conservation importance by usingThese are the commonest of the unimproved the standard criteria (Ratcl197iffe,7 ). meadows in East Sussex (Steve1990n);, there were In addition, reference was made to the sumanyrvey hayof meadows of this type in the study area. Most unimproved neutral grasslands in East Sussex (Stexampleseven, were of the widespreadLathyrus MG5a 1990) to give local context. This survey mainly pratensis sub-community. These ranged from species- concentrated on the Weald, often by a field-by-poorfield to more species-rich. Most examples were small search; wet meadows were poorly covered. No mandead owpartlys improved and were of Parish/ in the EIA study area were included in the rNeighbouegister. rhood value only, but the more species-rich, probably unimproved examples may be of County/ MG1 ARRHENATHERUM ELATIUSGRASSLAN D Metropolitan importance. The best example at Home Arrhenatherum elatiusgrasslan ds are characterised by Farm, Ambridge, is designated a SSSI as a hay meadow dominant Arrhenatherum, Dactylis glomerata, Holcus lana-and is of National Importance. tus and Heracleum sphondyliu.m They occur on freely One example of the less common type, MG5c draining to seasonally moist soils which are weaklDanthoniay decumbenssub-commun ity, was found. This acidic to calcareous, and which are often moderatis eknownly or from at least nine other sites (total 29.8 ha) in strongly nutrient-rich. They are usually ungrazed,East bu t Sussex. The meadow found was a moderate area may be mown. They are widespread in lowland(5 Britaiha) n on a steep slope within a large, partly improved on roadsides, banks, neglected pastures, etc. (RodwelMG5al example, and was assessed as of District/Borough et .,a l1991 et seq). . Although they are a fairly naturvalue.al vegetation type and are often fairly species-rich, they are thought to be a considerably modified NVCMG7 type LOLIUM, PERENNELEYS with generally low botanical interest198 (NCC,9). The y Lolium perenneleys are characterised by dominant are common in Britain. Lolium perenneassociated variably withPhleum pratense, In the study area, these grasslands occurred Poamainl trivialis,y Trifolium repens, Dactylis glomerata, Alopecurus on the roadsides and in a few neglected fields.pratensis, No Plantagospecies, Taraxacum species and other species-rich examples or areas of large extent nitropoccur. hilous herbaceous plants. They are typically very They are considered to be of Parish/Neighbourhospecies-pod oor communities characteristic of the more value. nutrient-rich and heavily improved soils of medium pH, which are usually well-drained. They are either MG5 CYNOSURUS CRISTATUS – CENTAUREA heavily grazed or are cut for hay or silage. They are the NIGRA MEADOWANDPASTURE predominant, modern agricultural pasture in lowland These grasslands are characterisedFestuca by rubr, a Britain (Rodwellet .,a l1991 et seq). . They are generally Cynosurus cristatu, sLotus corniculatu, sPlantago lanceolata, highly improved, species-poor, and intensively mana- Dactylis glomerata, Holcus lanatu, Trifoliums repens, ged. This is considered to be a considerably modified Centaurea nigra, Agrostis stolonifer, Anthoa xanthum odora- NVC type, with generally low botanical interest tum and Trifolium pratens. e They are typically species(NCC,- 1989). rich pastures but can be quite variable in compoThesition examples. in the study are of very low interest They occur on soils that are not high in nutrientsand therefore, classified as being of negligible neither acid nor alkaline, and which are freely conservationdrained. interest. Part III * Species

9 * Introduction to species assessment

9.1 SPECIES SURVEYING * the likely nature of any inherent bias; and AND MONITORING * advantages and disadvantages.

Chapter 10 of this part gives an introduction to the Each method is then described in three sections: theory and principles of population survey and (1) principles; (2) field methods; and (3) data anal- monitoring and describes the general methods ysis and interpretation. Data analysis is covered in used to estimate population size. These methods Part I,Section2.6, and Appendix 2.Thedataana- will often need to be tailored to suit the require- lysissectionsinthispartthereforerefertothese ments of the species being studied; this infor- sections unless other analysis specific to the mation is provided in the sections on species method is required. However, it should be remem- groups. bered that other tests may be appropriate; the Chapters 11–26 contain details of the standard reader should refer to Section 2.6 for a fuller dis- methods used to survey each group of species, cussion of data analysis. from fungi to mammals. Attributes that provide The availability of suitable habitat is a key attri- an indication of the condition of species in each bute defining the condition of a species. Species group are identified at the start of each chapter, monitoring will therefore require the monitoring and methodologies for monitoring these attributes of the condition of their habitats: refer to Part II for are described; references for further information general habitat monitoring methods. This attribute are listed at the end of the book. Specific recom- is generally not dealt with in this part, although it mendations and current survey and monitoring is referred to for species that are very sensitive to protocols for selected species that occur in the UK small changes in habitat condition, such as many and appear on Annex II of the EU Habitats and lichens. In such cases, regular monitoring of habi- Species Directive (apart from vagrant and introd- tat condition is of critical importance, but it may uced species) are described at the ends of these not necessarily require the use of techniques chapters. described in Part II. Each section contains a table summarising the When using this Handbook as a guide for select- methods covered. A brief summary of the following ing survey and monitoring methods and design- points is given: ing sampling schemes, you should look up the * the recommended groups for which the method is species that are to be surveyed in Chapters appropriate; 11–26. The tables at the start of these chapters * the type of data that the method provides (i.e. list the appropriate methods for surveying presence/absence, population size, etc.); them. Consult the relevant sections, and then * the efficiency of the method, i.e. the combined return to Part I to follow the steps for design- quantity and quality of data produced in relation ing a survey and monitoring programme and to cost and effort; sampling scheme (if the appropriate method * the precision obtainable; requires it).

# RPS Group plc and Scottish Natural Heritage 2005. 254 9 INTRODUCTION TO SPECIES

Having described the survey and monitoring species group, whether for site evaluation for methods available for each species group there EIA or conservation status assessment. A generic is then a section describing how data collected description of evaluation is given in Part I of this can be used in the conservation evaluation of the Handbook. 10 * General principles and methods for species

10.1 INTRODUCTION transects) or a point (point counts). Estimates of density can be calculated by adjusting for the fall- This section describes some general principles and off in detection with distance from the line or methods that are applicable to many of the species point. Software has been developed to allow rela- groups covered in Chapters 11–26. Methods have tively simple analysis of sophisticated distance been divided into several broad groups. These sampling methods (see Section 10.6). include total counts and methods that sample spe- In many cases, it is possible to employ a range of cies over defined areas or periods of time or both. different methods simultaneously to maximise There is, however, some overlap between them. For available data collection. For example, all quadrat example, quadrats may be sampled along a trans- and transect methods can be applied to several ect; fixed-radius point counts can be construed as species at once. circular quadrats. Where necessary, the reader will The other methods covered in this chapter are be referred to the relevant chapters. trapping webs, the removal method (used mainly Methods may be loosely divided into those for for estimating fish populations sampled with elec- sedentary species and those for mobile species. trofishing), and mark–recapture techniques. Sedentary species are often easier to sample. Quadrats may be used because, given enough time, all the individuals in a sample area can be counted. 10.2 TERMINOLOGY In contrast, mobile species may flee from observers. When sampling an area for mobile species, it is There are some inconsistencies in the names given necessary to obtain a ‘snapshot’ of how many indi- to different point and transect methods in the lit- viduals exist in that area before they move signifi- erature. To clarify and standardise these terms, an cantly, or react to the presence of the observer. For illustration of the different transect and point meth- a strip transect, density can be estimated by divid- ods and a summary of the nomenclature used in this ing the number of individuals seen by the area of Handbook is provided in Figure 10.1.Wehavechosen the transect. However, this estimate will be biased to differentiate one-dimensional transects, in which downwards if you are more likely to miss indivi- contacts are only recorded on the line, continuously duals that are further away from you as you make or intermittently, as line intercept and point inter- the observations. cept transects, respectively. Belt transects are lines If it is likely that individuals are being missed of contiguous or spaced-frame quadrats, whereas then it is worth considering distance sampling strip transects are very long, thin quadrats. ‘Line methods. Distance sampling is a generic method transect’ refers only to transects in which distances of estimating density, commonly applied to mobile are measured from the line to objects (either exactly animals, which takes into account the fact that or by grouping them into bands). Point counts, in individuals are often less detectable when they which objects are counted from a fixed point, are are further away from the observer. Distances to also referred to as ‘point transects’ in the context of individuals are estimated from a fixed line (line distance sampling.

# RPS Group plc and Scottish Natural Heritage 2005. 256 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

Point intercept transect X Recording presence/absence of species at set distances (x) along a line. Measures frequency.

Line intercept transect Continuous measurements of intercepts along a line. Normally used for estimating vegetation cover.

Belt transect Contiguous (above) or spaced (below) frame quadrats laid along a line. Each quadrat is recorded separately. Measures frequency, cover, density or other variables. Normally used to study changes along an environmental gradient or across vegetation boundaries.

Strip transect Essentially a very long and thin quadrat of fixed width; individuals are counted within this strip. Estimates density.

b a

Line transect A line walked by the surveyor who either places each individual within several distance bands (above) or estimates perpendicular distance to each individual (below). Estimates density and detectability.

Point transect/point count A count made within a fixed radius (left), within several distance bands (middle) or exact distance estimation from a b point (right). Estimates density and a detectability. Referred to as 'point transects' by Buckland et al. (1993) as they can be considered as transects of zero length. The right-hand example is also known as a Variable Circular Plot (VCP).

Figure 10.1. Types of transect and point count. 10.4 Timed searches 257

10.3 TOTAL COUNTS standardise the surveying of cryptic species, or species spread over a wide area, which cannot 10.3.1 Principles and methods easily be sampled by using transects or point If you are surveying a conspicuous species in a counts. For example, timed counts provide a sim- small area, or an aggregating species, it may be ple and efficient means of obtaining estimates of possible to count the entire population and arrive relative abundance of Odonata (the order of at an accurate assessment of population size. insects including dragonflies and damselflies) in However, it is unlikely that you will be able to wetlands where the terrain would make transects make total counts with confidence very often. problematic (Section 16.2.4). Another example An example in which total counts may be appro- would be counting birds flying past a headland; priate is when the number of orchids in a meadow in this case the area of search cannot be easily needs to be established; if the sward is short and quantified. In both cases, searching for a set the orchids are very conspicuous, then counts will amount of time introduces an element of standar- be accurate. Total counts of plant species are cov- disation, which can be repeated in subsequent ered in more detail in Sections 15.2.1 and 15.2.2. surveys. Counting breeding seabirds is another situation in which total counts are often employed. 10.4.2 Methods However, if you cannot be certain that the whole population has been counted, data should be pre- Timed searches are often used when surveying for sented as a minimum population estimate. This presence–absence of a species; the surveyor walks may well be sufficient if you only need to check around a site looking for the target species, and if that the population is above a lower limit. nothing is found after a set time an absence is If the species is mobile and widespread, several recorded for that visit. If several such surveys fail surveyors will be needed to make simultaneous to register a presence, it can usually be concluded counts at different sites to ensure that individuals that the species is absent (although this will are not counted more than once. This is the method depend on the intensity of the search; absence is used for surveying wading birds: surveys are syn- hard to demonstrate conclusively). chronised to minimise the chance of a flock of It is usual to further standardise timed search birds moving from one site to another between surveys by searching only within a delineated counts (Section 24.2.1). area; this enables a minimum density to be estimated.Ifthesiteissolargethatasurveyorcannot cover the whole area adequately within the time 10.3.2 Analysis allotted for the survey, it should be subdivided In principle, a total count is the total population, so into sample areas, and a random sample of these if counts change over time no analysis is needed to selected for searching. The size of search area demonstrate a change between years. Regression chosen will depend upon the size of the analysis or time-series analysis may, however, be site and the ecology of the target species. necessary to establish whether there are significant Presence–absence searches for scarce and/or trends over a number of years, particularly if the widely dispersed species will generally need to population exhibits cyclical changes. be undertaken over a large area. For quantitative repeat monitoring surveys, numerous smaller sample areas should be searched for a shorter 10.4 TIMED SEARCHES time in order to generate more data from each 10.4.1 Principles survey. Quadrats (Section 10.5) may be appropriate to select such areas for searching. This is parti- Timed searches (also termed timed counts, direct cularly appropriate for smaller species with high counts or direct searches) can be used to population densities. 258 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

10.4.3 Analysis calculation of the precision in this estimate. Results from different years can be compared sta- The analysis of presence–absence surveys is tistically by using the methods outlined above. obviously straightforward if the species is found. It should be remembered that timed counts will Confirming an absence is more problematic. vary according to the efficiency of surveyors and Unless a species is sufficiently conspicuous and the nature of the terrain. Methods should therefore identifiable to guarantee detection, and the site be standardised and documented with as much has been comprehensively searched (which will detail as possible to ensure comparability. rarely be the case), then it cannot be said for certain that the species is absent. Several thorough surveys with negative results will be needed before it may 10.5 QUADRATS be reliably assumed that a species is absent. 10.5.1 Principles Presence–absence data from different areas can be used to build up a distribution map of the spe- Quadrats are used to define sample areas within cies, which can be updated periodically to detect which measurements of some sort are taken. The changes in range. selection of quadrat locations can be made by jud- Data from timed searches that involve counts gement, systematically, or randomly. This subject can be expressed as numbers found per unit time is covered in detail in Part I, Sections 2.3.3 and (divide total number found by duration of survey). 2.3.4, and is not repeated here. A mean figure and confidence limits can be calcu- The measurements taken within quadrats will lated if an appropriate sampling method has been depend on the species being surveyed and the used. Such data can be treated as an index of popu- objectives of the study or monitoring programme. lation; results from different years can be com- The simplest measurement is presence–absence of pared statistically to look for trends in the data, a species within the quadrat. If repeated in many provided consistency can be assured. Analysis can quadrats an estimate of overall percentage fre- be in the form of t-tests, analysis of variance or quency can be obtained. Alternatively, if a quadrat regression, although non-parametric analyses may with subdivisions is used, presence–absence in be required if distributional assumptions cannot each subdivision can be recorded and an overall be satisfied (see Part I, Section 2.6.4). percentage of subdivisions containing the species Data from timed searches in a set area can be can be calculated per quadrat (referred to here as used to estimate a minimum density in that area (as sub-plot frequency). Other measurements com- well as numbers per unit time as above). Again, this monly recorded are density (number of individuals should be treated as an index (or a minimum den- within the quadrat) and cover (of plants: a measure- sity), because it is unlikely that all individuals will ment of the area of substrate covered by a perpen- be found. This estimate can be extrapolated across dicular projection of foliage and stems). These are areas of similar habitat to obtain a total population described in more detail in Part I, Section 2.1.2. index. It might also be possible to calibrate timed The size of quadrat will affect measures of fre- search results by carrying out a timed search in one quency (Appendix 4). It is obvious that a larger area for the standard length of time, and then con- quadrat will have a greater chance of recording tinuing the search intensively until you are reason- presence of a particular species than a smaller ably confident that all individuals have been found. one. Quadrat size therefore needs to be such that The ratio of individuals found in the timed search extreme percentage frequencies are avoided (i.e. to total individuals found can be used to derive a the species is neither nearly always present nor multiplier, which can be applied to other timed nearly always absent). Once selected, it is of course searches to estimate total numbers. This calibra- vital that quadrat size be kept constant between tion should be carried out more than once to obtain repeat surveys. Nevertheless, where possible, a better estimate of the multiplier and to enable small quadrats should be used for frequency 10.5 Quadrats 259

estimates as these are more easily and accurately may affect the species being monitored; they must searched. When counting individuals to obtain be relocated from markers such as posts or trans- density estimates, quadrat size does not affect the ponders. See Appendix 5 for instructions on the measurement in principle, although the larger the installation of permanent markers. quadrat the more likely it is that some individuals will be missed. Quadrat size should be such that samples can be gathered efficiently; if quadrats are 10.5.3 Temporary quadrats too large, they will take too long to record. If they Temporary quadrats have the advantages of being are too small, the target species may not be quicker to locate, less damaging to the surrounding sampled even if it is present, especially if it is environment and, if located correctly, always rare. A fuller discussion of the selection of appro- representative of the habitat as a whole (perma- priate quadrat size and a list of commonly used nent quadrats may become unrepresentative as a sizes for different plant species is given in result of chance events or successional change). Appendix 4. However, they usually produce less precise estimates of change for a given sample size. 10.5.2 Permanent quadrats Temporary quadrat locations are particularly appropriate for ephemeral plant species or short- Permanent quadrat locations provide a good way of distance mobile species such as ground beetles or reducing between-quadrat variability when benthic invertebrates. changes over time are being monitored. If changes Many of these advantages and disadvantages of are fairly consistent across the site, permanent permanent and temporary quadrats apply equally plots will detect change more efficiently than will to some types of transect (Section 10.7). Further temporary plots. They can therefore give a more discussion of the advantages and disadvantages of precise measure of change. They are also appropri- permanent and temporary quadrats is provided in ate when monitoring rare sedentary species that Part I, Section 2.3.3. occur in a few known locations. For example, the health of specific lichen colonies is often monitored by using permanent quadrats that are delib- 10.5.4 Methods and analysis erately placed over them (Section 12.2.2). In such circumstances, random temporary quadrats would Quadrat methodology and analysis for plant spe- be highly inefficient and imprecise; such quadrats cies is covered in detail in Part II, Sections may not coincide with colonies at all. However, 6.4.2–6.4.5, 6.5.2 and 6.5.3. For other species, the permanent quadrats that are placed by judgement precise methodology may vary depending upon the cannot provide a reliable assessment of trends over nature of the species being surveyed, but in general the whole site unless they cover the whole of the the species will simply be counted within the quad- population. Therefore, if information is needed on rat, either for frequency data or for density (and whether other colonies are being established, hence population size) estimation. For species that numerous randomly or systematically located are difficult to identify in the field, collecting quadrats will be required. equipment will be necessary; see the relevant chap- Another advantage of permanent quadrats is ters on the species groups for the equipment that more data can be collected on the survival required. It is important that samples be labelled and growth of individual organisms (especially clearly so that the location from which they were plants) within the quadrat. However, there is a taken can be ascertained for later analysis. risk that permanent quadrats, particularly if Analysis of quadrat data can be straightforward located in fragile habitats such as peat bogs, for monitoring purposes; the most important ana- might damage the species being monitored. lysis will be the examination of trends in the range, Quadrats should never be left in situ because they frequency and abundance of the target species. 260 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

Frequency data can be analysed by using a 2 test. 3. Objects must be detected before they move appre- Cover and density (or abundance) can usually be ciably in response to the approach of an observer. analysed by using t-tests, analysis of variance or 4. Distances must be measured accurately. regression. Non-parametric statistics may be more appropriate, depending on the distribution of the Assumption 1 is addressed by positioning lines or data; for a fuller discussion of data analysis refer to points systematically or randomly so that they Part I, Section 2.6. provide a representative sample of the area being studied. Lines or points should not be located along footpaths, roads or field boundaries; this 10.6 DISTANCE SAMPLING introduces unknown bias into the sample as these are likely to be atypical in terms of species 10.6.1 General principles density. Assumption 2 may be difficult to achieve in ship- Distance sampling is a method of obtaining density based surveys, for example, or if individuals are estimates for species, based on estimating dis- often hidden in undergrowth. Careful design can tances to individuals from a line or a point. The often overcome this difficulty, for example by major advantage of this approach is that detection using multiple observers, but in extreme cases it does not have to be complete, as the method pro- may be necessary to estimate the percentage vides a means of estimating the number of missed detected on the line and adjust density estimates individuals within a given distance from the obser- accordingly. ver. The method is most commonly applied to Assumption 3 is a problem if it is possible that mobile species such as mammals and birds, but is individuals will move appreciably towards or also well suited to many slow-moving or stationary away from the observer prior to detection. organisms (Buckland et al., 2001). Movement of objects towards the observer (a com- The number of objects recorded will always mon behaviour among some passerine birds, for decrease with distance from the observer. Unless example) could increase the density estimate. species are sedentary and it can be guaranteed that Alternatively, objects may flee the observer, they are obvious enough not to be overlooked, it is which will bias the results in the opposite direc- safest to assume that the observer will fail to detect tion.Biasofthiskindisfurtherexacerbatedifthe all individuals. Analysis of distance data involves object moves and is recorded twice from the same modelling the decline in detectability with dis- point or line. The principle of distance sampling is tance from the observer and using this to calculate that each count provides a ‘snapshot’ of objects a corrected density estimate. occurring around the point or line. As long as the The choice of whether to sample with line trans- speed of objects moving before and up to the time ects or at points (point transects) will depend on of detection is appreciably slower (less than one several factors, including the time available to col- third) than that of the observer, random move- lect data, the mobility or elusiveness of the species in ment of objects is not likely to be a concern question, the density of the species, whether more when using line transects. The methods cannot than one species is being studied, and the nature and be used to count rapidly moving objects such as variability of the habitat (see Section 10.6.2). There most birds in flight. Random movement is more of are a number of important assumptions that need to a concern with point counts, as bias arising from be met if either of these distance sampling methods errors increases with the square of distance for are to produce reliable density estimates. points but only linearly for lines. 1. Objects must be distributed randomly with Counting the same object twice from a different respect to the sample lines or points. line or point does not violate any of the assump- 2. Objects exactly on the line or point must be tions made by distance sampling methods. If dou- detected with certainty. ble counting is commonplace, however, it may be 10.6 Distance sampling 261

due to a weakness in the method. For example, follow and dense vegetation makes disturbance when carrying out flush counts of grouse by using and detection problems significant. It is also easier dogs and multiple observers, it is important that to locate points randomly in habitats where access birds are not flushed from one transect to the next. is a problem. They also allow an observer more Assumption 4 is important and it is worth invest- time to locate individuals in habitats where they ing some time into training observers to measure may miss them while concentrating on walking distances accurately. A better option is to use a a line. laser range-finder. These are very accurate and The time spent at a point is critical. The aim affordable and greatly improve the reliability of is to spend the minimum amount of time that distance measurement and therefore of density is necessary to detect all individuals present at estimates. A high-quality compass is also needed, the beginning of the count period, in order to as distance from the line is usually measured by minimise the probability of animals entering or using distance from the observer and the angle leaving the area during the count period. As a between a line from the observer to the individual rule, somewhere between five and ten minutes and the transect (see Box 10.1). is probably long enough to record all the indi- If it is impracticable to measure distance accu- viduals of a species in the vicinity of the point. rately, it may be useful to group distances at inter- Any longer and random movement of objects vals into bands. If only two intervals are used an may cause an increased or decreased density assumption has to be made about the way in which estimate. detectability declines with distance, and it is not When conducting point counts, it is much more possible to compare different models to find which important to be aware of bias associated with clus- one fits best. Hence, three intervals or more are ters (herds of animals or flocks of birds), although recommended. This method is often used in multi- this is also a consideration with line transects. There ple species projects, such as the national BTO/RSPB/ are a number of reasons for detectability varying JNCC Breeding Bird Survey (BBS). This method is with cluster size. For instance, larger groups may favoured for such projects because it would take a be more vocal and therefore recorded more often at considerable amount of time to measure exact dis- greater distances. On the other hand, large groups tances for the large number of species involved, may be more alert and less likely to be recorded, and it provides a reasonably robust way of dealing particularly in dense vegetation. The calls of some with detectability problems. However, for more bird species may also trigger others to respond. This species-specific work it may be useful to consider may be a particular problem when surveying song- taking exact measurements. birds. Sometimes it may be better to measure the distance to clusters, rather than to each individual, 10.6.2 Line and point transects and estimate the size of the cluster. Distance analysis software (Section 10.6.4) can analyse clustered The assumptions for distance estimation from data and provides methods for studying, and cor- points are the same as for line transects (Section recting for, the relation between probability of 10.6.1). Line transects have a number of advantages detection and cluster size. Point methods are parti- over point methods when carrying out distance cularly susceptible to bias arising from error, so it is sampling. They are more efficient at collecting very important to choose a good model for the data large sample sizes and less prone to bias from mea- (see Section 10.6.4). surement errors. Line transects are also less biased Whether using transects or points, it is impor- by species mobility and are more suitable than tant to standardise the method of data collection as point counts for open habitats in which species much as possible. This includes removing possible can be detected at long distances. sources of bias, for example by walking each trans- Point transects are often used in habitats such as ect at a standard speed and not surveying in diffi- woodland, where line transects may be difficult to cult weather conditions. 262 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

Box 10.1 Methods of estimating distances by If the location of the object is marked in relation using the line transect method to a tree, field edge or other feature, a tape measure can be used to check distances later. These days, Whenever estimating distances to objects on line it is much more usual to employ an optical transects, the critical distance is perpendicular to the range-finder. In projects in which objects are line (see FigureB10. 1a). A degree of error is possiblecommonly in recorded over 100 m, survey lasers are estimating perpendicular distances to objects that are useful to determine distances accurately. Their cost is a long way ahead of the observer and close to the line. soon justified by the ability to precisely determine These are often erroneously rounded to zero. Accurate distances up to several hundred metres. Combined angle measurement is important and, if distances are with a good-quality compass, distance from observer visually estimated, then thorough training and to object can be recorded along with angles and repeated self-checking against measured distances accurate perpendicular distances calculated by using should be used. For band methods, the object only has tr i g on o me tr yB (1 seb0) . e.1 F i g u r e to be recorded in the correct band, so the skill necessary in the field is less daunting.

(a) (b) x1 x2

Distance to object D D = x sin A x3 Object = object x4 x A 25 m Walking 100 m Walking Observer direction direction

Figure B10.1

10.6.3 Field methods obtained by using a fairly small number of distance bands. Another advantage is that distances Transects can always be grouped into bands at the analytical Exact distances stage if necessary, without being tied to a prede- The method involves walking along a transect and fined grouping. For example, distances may be estimating the distance to objects either side of the found to have been rounded in the field, and pro- line. The distance perpendicular to the line is mea- blems with heaping at, say, 10 m intervals can sured, either directly or as a combination of dis- often be dealt with by forming appropriate distance and angle from the line (see Box 10.1). tance bands. A large number of intervals may improve the Distance bands estimation of the detection function, but during Collecting exact distance data is the preferred fieldwork it will become more difficult to ascer- method as it allows more sophisticated modell- tain which distance band an object falls into ing of the detection function (Section 10.6.4), the further away it is (unless laser range-finders although similar levels of precision can often be are used). 10.6 Distance sampling 263

Methods involve walking along a transect, esti- at a point early, and spend a few minutes in silence mating the distance to objects either side of the line so that your presence does not affect the behaviour and placing them in discrete distance bands, e.g. of the target species. Movement of objects towards 0–10 m, 10–25 m, 25–50 m, 50–100 m and >100 m. or away from the observer is another source of con- The distance perpendicular to the line is measured. siderable bias in point transects. There is no hard and fast rule to determine the width of the inner band. Ideally, there should be at 10.6.4 Analysis least two bands within the distance for which detection is almost certain. If there is evidence If distances are estimated, either exactly or in inter- that objects are moving away from the observer, vals, the decline of detectability with distance can however, it is important that the intervals are not be modelled and used to estimate the proportion so small that objects move between them before of undetected individuals and hence to derive a they are detected. density estimate. Conventionally, data from the outer unlimited Numbers of individuals detected at increasing distance band is omitted from analysis. This is distances from the observer can be plotted as a because interpretation of data recorded to an infi- histogram, with distance from the line or point on nite distance is complex and also because outlying the x axis and number of detections on the y axis. observations can unduly affect the fit of the detec- A curve fitted through the data describes the change tion function. Although it is possible to calculate in detectability with distance: this is termed the density estimates manually, use of the Distance soft- detection function (Figure 10.2). Detection functions ware is recommended for simplicity (see Section will normally vary for different species in the same 10.6.4). The detection function is usually assumed habitat and for the same species in different habit- to be half-normal for two-band methods, but using ats. A separate detection function can be modelled more bands allows the choice of the optimal model for each species and habitat. using the Distance software (Section 10.6.4). This function is best modelled by using the dedicated Distance software, which can be used to fit Point transects four basic mathematical models (known as key The method involves counting objects for a fixed functions) to the data. Each model produces a period of time at a point and either estimating the differently shaped detection function based on a exact distance to them or placing them in discrete different assumption about the way in which distance bands. The general field method princi- detectability decreases with distance. These key ples are similar to those for transects. functions have been chosen as they reliably reflect In the case of birds, many of the contacts will be the nature of most biological distance data. For by sound only, and observers will need to be com- example, the detection function in Figure 10.2 is petent at estimating such distances accurately. modelled with a half-normal curve. Laser range-finders can be used to improve distance If distance intervals are used, the number and estimation to visible objects. Time spent at a point spacing of intervals will depend on the level of should be long enough to record everything in the accuracy required. Buckland et al. (2001) suggest vicinity but not so long that there is significant that ideally there should be at least two distance movement of objects into the area. Estimation of bands on the ‘shoulder’ of the curve (i.e. before the optimum count time will require either exist- detectability begins to decline appreciably): see ing knowledge of the behaviour of the species (e.g. Figure 10.2. This will help to improve the model song frequency in birds) or a pilot survey. fit of the detection function. This modelling For mobile species, few will be recorded near to assumption is known as the ‘shape criterion’ and the point itself. This is both because it is where the roughly means that detectability must remain cer- observer stands and also because the area close to tain, or near certain, for some distance from the the observer is small. It is therefore useful to arrive line or point. 264 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

Once an acceptable detection function has been fitted, Distance will calculate estimates for population density and size with associated standard errors and confidence intervals. One potential drawback of distance sampling is that sample sizes need to be quite large to model the detection function reliably. About 60 encounters are typically required to derive a reliable density estimate. Obviously for the scarcer species some intense surveying may be required. If the survey is repeated, then the model can be improved with additional data and old estimates re-analysed. Distance sampling methods are explained in relation to particular species in the relevant sections. The computer program Distance is a fairly straightforward and versatile alternative to manual calculation. A Windows-based version is available to download from the internet via the Distance homepage at the University of St Andrews (www.ruwpa.st-and.ac.uk/distance). To keep up to Figure 10.2. Histogram showing distance data for date with information on Distance, it is recom- Lapwing Vanellus vanellus surveyed in grassland. A mended that you check the Distance homepage half-normal curve with one cosine adjustment term and subscribe to the e-mail discussion group. This is shown as a model for the detection function. is done by e-mailing [email protected] and typing: join distance-sampling . Distance software provides ways of selecting the Guidelines for modelling data by using Distance best model and testing the model fit. Careful selec- are described in the book Introduction to Distance tion of the best model is particularly important for Sampling (Buckland et al., 2001). At the time of writ- point transect data. ing, an earlier version of this book could be down- It is often desirable to discard any outlying loaded from the above website. observations before fitting the detection function as these can have undue influence on the result- 10.7 LINE AND STRIP TRANSECTS ing model. If necessary, the function can be fine tuned to improve the fit by using a further set of 10.7.1 General principles ‘adjustment terms’ (for example, the detection Transect methods involve moving along a line function in Figure 10.2 has been adjusted with between two points and counting the number of one term from a cosine series expansion). For objects observed on either side of the line. We con- details on the modelling procedure consult sider the following methods: Buckland et al.(2001). Clustered data, from herds or flocks for exam- * line transects (exact distances to each contact is ple, can also be handled by Distance. Each cluster estimated, or contacts are grouped at intervals (or group) is modelled as a separate record and the into distance bands), already discussed in Section average group size used to provide estimates of 10.6; density or population size. The possibility that * line transects (infinite width); small groups are less detectable away from the * strip transects (species are recorded within a single line can also be taken into account. defined perpendicular distance from the line); and 10.7 Line and strip transects 265

* line intercept or point intercept transects (counts statistics such as the Mann–Whitney test or are made of species that the line ‘touches’). Kruskal–Wallis test. Of the above methods, only the first (in which distances are estimated exactly or measured in bands) 10.7.3 Strip transects will yield reliable density estimates if a substantial Principles number of individuals remain undetected. A strip transect is essentially a long, narrow quad- Infinite width transects can be useful to provide rat. It is assumed that all individuals within the an index of abundance for a species for a long-term strip are counted; individuals outside the strip are monitoring exercise. However, they cannot be used ignored. Strip transects can be used to sample to compare the density of species in different habi- immobile or sedentary species such as plants or tats, because this would require some assumption snails, for which it is possible to be certain that about the shape of the detection function for each individuals have not moved in or out of the strip habitat. The lack of distance data would also pre- while the search is being conducted. In this case, clude a reliable estimation of density within the the strip will typically be very narrow (a few metres sample area as there would be no way of knowing wide at most) in order to reduce the time taken to how many objects had been missed. search the strip and increase the likelihood of Strip transects require intensive surveying of counting all individuals. the transect area in order to be sure that objects Strip transects can also be used to sample mobile are not being overlooked. Line and point intercept animals when it is not possible to search inten- transects require objects to remain stationary and sively before their positions change. This method are therefore applied only to sessile organisms is only likely to prove useful when detectability such as plants. constraints are not a consideration, i.e. the terrain is uniform and species are conspicuous, for example 10.7.2 Line transects: infinite width rabbits or hares on short turf.

Principles Analysis Line transects of infinite width can be used to col- Strip transects should be designed so that it can be lect encounter rates, calculated as objects seen per reliably assumed that all individuals within them unit time or per unit of transect length. Distances are certain to be detected. This is more likely to be are not estimated, and therefore density estimation the case for immobile species. Density may be cal- is not possible unless the species is very conspicu- culated by simply dividing the number of objects ous and the habitat is open and detectability can by the area of the strip. A mean density and var- therefore be assumed to be constant with increas- iance can be calculated from the sample of trans- ing distance. This assumption is very unlikely to be ects, and a total population estimate can be met, so this method should only be used for deriv- obtained by multiplying the mean density by ing population indices. the total area of similar habitat. Repeat counts from different years can be analysed by using Analysis methods such as t-tests and regression or their Counts made from transects with infinite width non-parametric equivalents. can be interpreted as indices of abundance, either For mobile species the optimum strip width is between sites (if it can be proved that detectability hard to determine. Observers may be surprised by remains constant) or over time in monitoring exer- how narrow such a strip needs to be, particularly in cises. Counts can be compared over time by trans- dense habitats such as scrub and woodland. If the forming the data (Part I, Section 2.6.4) and aim of the project is to compare the abundance of a analysing with parametric statistics such as t-tests species at two sites or in two different environ- or analysis of variance or by using non-parametric ments this is especially important, as differences 266 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

in detectability between sites could render the species that will not fleefromtheobserver.An comparison of results invalid. It is therefore worth infinite-radius plot may be used to provide an considering collecting distance data to enable index of abundance for any one species. adjustment for incomplete detection (Section 10.6). However, as with transects of infinite width, the lack of distance data would preclude any esti- 10.7.4 Line intercept and point intercept mation of density within the sample area as there transects would be no way of knowing how many objects had been missed. It also means that the results Principles cannot be compared between sites if the These are the most basic types of transect, in which detectability of the species varies in different the transect is a simple one-dimensional line. Only habitats. individuals that touch the line are recorded. Line intercept transects record touches continuously 10.8.2 Point counts in a circle of fixed along the line. Point intercepts record touches at radius or infinite distance regular intervals along the line. This can be used to estimate relative abundance, cover and frequency. Principles These transects cannot be used to survey mobile Point counts may be of infinite radius and used to species, and are normally used for vegetation. See collect encounter rates, calculated as objects seen Part II, Section 6.4.6 for more details. per unit time. They may also be of fixed radius, with individuals recorded only if they are within a Analysis certain distance. The latter method may be used to The analysis of line intercept and point intercept derive density estimates providing it is certain that transects is discussed in Part II, Section 6.4.6. all objects were detected within the fixed distance. Detectability problems can have a profound effect on point count results and detection may only be 10.8 POINT COUNTS certain to a short distance. Distance sampling 10.8.1 General principles methods may be more efficient as more data can be utilised from each point. Point counts involve counting and/or measuring distances to objects in all directions from a point. Field methods If distances are estimated to objects from the point, The method involves carrying out a standardised, the method is also known as point transects timed count from a point. If the species concerned (Buckland et al., 2001) or variable circular plots is sedentary and a fixed-radius circle is used, then (VCPs). A simpler method is to count the number an intensive survey within the circle may reveal all of objects in a circle of known radius. the objects. If the objects are mobile, then the We consider the following methods: observer must ignore any observations made beyond the critical distance at which detectability * estimating exact distances to each individual or declines significantly. grouping into distance bands (already discussed in Section 10.6); and Analysis * recording species within a single defined distance Counts made to an infinite distance can only be from the point or to infinity. interpreted as indices of abundance, either between Fixed-radius circular plots can be used to provide sites (if it is proved that detectability remains density estimates providing that objects are only constant) or over time in monitoring exercises. recorded to the distance within which they are A fixed-radius point count designed to ensure that certain to be detected. These counts are more all objects within the area are certain to be detected likely to be suitable for sessile or slow-moving may derive densities calculated by dividing the 10.9 Trapping webs 267

number of objects by the area surveyed. In habitats series of concentric circles of traps, each contain- with dense vegetation such as woodland or scrub ing the same number of traps. The traps are usually the radius may need to be particularly small. If arranged in lines like the spokes of a wheel, for theaimoftheprojectistocomparetheabun- convenience of relocation. The circles should be dance of a species at two sites or in two different arranged so that they lie a constant distance environments it is important to be especially apart, and so that the inner circle has a radius of careful, as differences in detectability between half that constant distance (Figure 10.3). sites could render comparisons of the data inva- Three basic assumptions are made: lid. It is therefore worth considering collecting 1. that all the animals in the centre of the web are distance data either in bands or as exact distances caught; (Section 10.6). 2. that population density is constant throughout The analysis of counts from point counts of the area of the trapping web; and infinite distance or fixed radius is identical to 3. that probability of capture is homogeneous that described for line transects of infinite throughout all trapping occasions. width (Section 10.7.2) or strip transects (Section 10.7.3). 10.9.2 Methods and analysis 10.9 TRAPPING WEBS Animals are caught over several capture occa- 10.9.1 Principles sions until no more animals are caught in the central traps. It is likely that new animals will Trapping webs can be used for obtaining abun- still be caught in the outer circles, for although dance estimates of animals that are not easily the number of traps is constant they sit in a observed or efficiently surveyed by visual search- larger area, containing more animals, than do ing methods. They are most often used for small the inner traps. The number of animals caught mammals and invertebrates. A trapping web is a in the outermost circles will be greater than the number caught in circles slightly further in, because the outermost traps will be catching animals from outside the web. If this immigration is obvious, the data from the outermost circles should be discarded. It is best to mark and release captures rather than remove them unless one is sure that immigra- X tion will not occur. The removal of animals may X simply create a vacant territory, which will be occu- X pied by an individual from outside; this will bias results considerably, and cause the population to be overestimated. Population estimation is a complex procedure, but is based on the fact that animals near the centre are more likely to be caught than those near the edge. It is then theoretically possible to work out differences in probability of capture, although this is complicated by the fact that the inner traps interfere with each other. See Greenwood (1996) and Figure 10.3. Illustration of trap layout for a trapping Anderson et al. (1983) for further details of analysis web. X is the constant separating rings of traps (see text). methods. 268 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

10.10 REMOVAL METHOD of the total number of fish in that section of water can be obtained. Removal techniques are not 10.10.1 Principles and applications usually applicable for monitoring terrestrial ani- The removal method is a way of estimating popula- mals. Consult Seber (1982) and Greenwood (1996) tion size based on trapping, whereby trapped ani- for further information. mals are removed from the population. In the extreme case, trapping continues until no more 10.11 MARK–RECAPTURE TECHNIQUES animals are being caught. The number of captures is then taken as the total population size. In prac- 10.11.1 Principles tice, this usually requires too much effort. A sample of animals from a population is caught, However, if the cumulative numbers caught in marked and released back into the population. If each trapping occasion are plotted against catch the marked animals disperse throughout the total per unit effort (for example, mean number of population, the ratio of marked to unmarked catches per trap) a line can be fitted to the data individuals in a second sample will be the same as with linear regression and extrapolated to obtain the ratio in the whole population. The population an estimate of the total population (see Figure 10.4). size can thus be estimated from two trapping It is important that catch effort be evaluated occasions. correctly. For example, doubling the number of This can be expressed algebraically as follows: traps may not double the true catching effort if the traps interfere with each other. Alternatively, if there are not enough traps, the number of cap- m n 2 ¼ 1 , tures may be too small for reliable estimation. n2 N The removal method is only appropriate for populations that are closed (i.e. no new individuals where m = number of marked animals in second enter the population while trapping is taking place). 2 sample; For monitoring purposes, this method is gener- n = total number of animals in second ally only applied to monitoring fish populations 2 sample; with electrofishing (Section 21.2.9): a section of n = total number of animals caught and water can be isolated with stop nets, and electro- 1 marked in first sample; fishing is carried out until few fish are being N = total population size. caught. Catch per unit effort can be expressed as the number of fish caught in each sweep; the All mark–recapture techniques are based on this results are plotted as in Figure 10.4 and an estimate fundamental premise, although there are many refinements of the theory. Most methods that are commonly used require more than two trapping 14 12 occasions. 10 There are some fundamental assumptions inher- 8 ent in the use of mark–recapture models, which 6 4 must be understood; if these assumptions do not 2 hold for the population under study, the results

Catch per unit effort 0 0 50 100 150 200 250 300 350 may be invalid. Cumulative catch * Marked individuals must disperse throughout the Figure 10.4. The removal method. The graph depicts entire population once released. If the marked a hypothetical removal experiment with the animals stay in the group in which they were regression line added. The point at which the line cuts released, a second sample from the same area the x-axis is the estimated total population size. will contain a higher proportion of marked 10.11 Mark—recapture techniques 269

individuals than exists in the whole population, and thus the population will be underestimated. 10.11.2 Marking methods Conversely, a sample from a different area will A wide variety of methods can be employed to contain a lower proportion of marked individuals mark captured animals. The most preferable and the population will be overestimated. option is to use natural characteristics of the spe- * Every animal in the population must be equally at cies for subsequent recognition so that the animals risk of capture on every trapping occasion. If ani- do not have to be marked at all. The belly patterns mals become trap-happy (more likely to be recap- of Great Crested Newts, for example, are individu- tured) or trap-shy (less likely to be recaptured), the ally distinct. For animals that have to be marked, results will be biased. Refinements to some models you should avoid intrusive marking methods (such have been made that allow for differences in trap- as toe-clipping) wherever possible to avoid or mini- ping probability. mise the risk of causing injury or distress, or alter- * Many models require the population to be closed. ing the behaviour of the animals (for example, the This means that no births, deaths, immigration or pain of toe-clipping can deter animals from trap emigration should occur for the duration of the areas). It is also important that the mark does not study. Some models have been developed that can make the individual more at risk of predation; if cope with open populations. However, these tend the marks affect mortality, population estimates to yield less precise population estimates. will be biased. Methods for marking animals are discussed in the sections on species groups for A thorough knowledge of the ecology of the target which mark–recapture studies are appropriate sur- species is therefore required if mark–recapture is vey and monitoring techniques. Note that in many to be used in order to select an appropriate model cases a licence will also be required. that does not contain assumptions that will be Animals can either be batch-marked, whereby violated. For example, the assumption of a closed every animal caught is given a mark that identifies population can be made for adult newts in breed- the trapping occasion, or individually marked. ing ponds over a short time, but may not be justi- Batch-marking is suitable for most mark–recapture fied over longer periods, especially if there are models, but individual marking yields additional other ponds nearby. information and allows estimates to be made of It is important to realise that mark–recapture variations in capture probability. methods can produce disappointingly imprecise results given the amount of effort that is necessary. The higher the proportion of the population 10.11.3 Mark–recapture models caught, the better the precision obtainable. However, there are advantages with mark– recap- A number of different models exist, which differ in ture techniques: the standardisation of effort over the assumptions they make and statistical methods time is not as essential as it is with other sampling for analysis. The most widely used methods are methods. We are concerned with the ratio of new briefly summarised in Table 10.1, but for further captures to recaptures, and therefore trapping occa- information, detailed equations and other methods sions do not have to be standardised. For example, based on trapping and marking refer to Bibby et al. you can catch newts in pitfall traps, mark and release (2000), Greenwood (1996), Pollock et al. (1990)and them, and catch them a second time in bottle traps. Seber (1982). If marks are easily visible in the field (e.g. colour rings for birds), the ratio of marked to unmarked 10.11.4 Mark–recapture analysis individuals can be estimated without any need for subsequent trapping. This also has the advantage of It is beyond the scope of this Handbook to give detailed reducing the disturbance caused to the species and accounts of the analysis of mark–recapture data. For avoiding the problem of trap response. further information see Greenwood (1996), Pollock 270 10 GENERAL PRINCIPLES AND METHODS FOR SPECIES

Table 10.1. A summary of some commonly used mark–recapture models

Method Summary

Petersen The most basic method, involving two capture occasions. It requires closed populations with homogeneous capture probability. Also known as the Lincoln index. Mathematically simple. Schnabel Makes the same assumptions as the Petersen method, but can be applied to more than two capture occasions. Unmarked animals in each capture are marked. The method looks at the increase in the proportion of marked animals as the number of capture occasions increases, and extrapolates to the point at which the proportion is 1.0 and the number of marked animals equals the population size. Burnham & Requires a closed population and several capture occasions but allows for heterogeneity of Overton capture probability between individuals. Critical assumption is that capture probability does not change with time; trapping effort must be constant and trap response avoided. Jolly–Seber Can be used for open populations. Requires at least three trapping occasions and at least batch-specific marks. As well as allowing for gains and losses, the method estimates the number of animals entering the population and the survival rate.

et al. (1990), Seber (1982), Burnham & Overton (1978, chooses the most appropriate model for the data. 1979), Otis et al. (1978)andWhiteet al. (1982). Other useful programs are JOLLY, a DOS-based Mark–recapture analysis can be very complex. program for open populations, which estimates Computer programs have been developed to carry survival rates, and JOLLYAGE, a refinement of out this analysis; software and instruction manuals JOLLY, which allows age-class data to be included can be downloaded free from the internet at in the Jolly–Seber analysis. Methods from these www.mbr.nbs.gov/software.html. These programs programs are also available in the more user- include CAPTURE, a Windows-based program for friendly Windows-based package called MARK. analysing closed populations, which contains It is important that the theory behind the analy- several different models to allow for variations in sis is understood before using programs so that you capture probability by time and individual. It can have confidence in the ecological explanation also contains a model selection procedure, which of model selection and population estimates. 11 * Fungi

The groups of fungi covered in this section are absence (or reduction in numbers) of the sporomes restricted to the macromycetes. This is not a pre- of a species in one year does not necessarily imply cise taxonomic definition (it generally includes a reduction in range or numbers of that species; the the basidiomycetes minus rusts, smuts and yeasts species may very well still be present and will fruit with some ascomycetes and myxomycetes), but it is again when conditions are favourable. Monitoring of convenient and commonly used (Watling, 1995). fungi therefore must be undertaken with a view Although this grouping generally applies to the to making long-term studies. The minimum length mushrooms and toadstools (correctly termed aga- of time over which actual changes in distribution or rics), polypores and their relatives and jelly fungi, abundance can be realistically assessed is five years; a few prominent ascomycetes such as the earth Orton (1986) recommends 10 years as a reasonable tongues, truffles and their allies are included. This minimum length. Studies of intervals of less than this grouping contains three different categories of period can do little more than confirm the presence fungi based on life strategy: biotrophs, which of a species; for EIA studies, this may be all that can include basidiolichens and mycorrhizal species; be realistically gained within the timescale of the saprotrophs, which include litter and wood rotters; overall project. and the necrotrophs or parasites. An informed bio- A further complication arises because of this logical approach should always be considered need for longer-term monitoring. In addition to when dealing with members of each category. For changes resulting from succession or alterations example, a wood rotter may be restricted to a single in site management practices, long-term trends tree trunk, whereas an ectomycorrhizal fungus caused by factors such as acid rain and climate may be associated with a widely spreading mycelial change will also affect the data. Separating the system that covers several square metres. effects of these factors, about the influence of The survey and monitoring of fungi presents some which we know very little, is problematic. difficulties that need to be taken into consideration The identification of some species of fungi may when designing a monitoring strategy. Surveying for need to be carried out by specialists; although some presence or absence of macromycetes depends upon species can be recognised in the field by generalist theappearanceofthefruitingbody(sporome).The staff, there are many (particularly some of the rarer number of fruiting bodies is considered to reflect the species) that will need experienced personnel to be health and spatial extent of a fungal colony, although certain of a correct identification. Although some there is little scientific evidence to support this. of the rare fungi are difficult to identify, there are Sporomeappearanceisinfluencedbyanumberof many that are not (for example the Pink Waxcap environmental factors including temperature, Hygrocybe calyptriformis; there is no other pastel pink amount and timing of rainfall, soil pH and nutrient Hygrocybe in Europe, nor is there another agaric like status, and successional patterns of surrounding it in colour and size). The observer should, how- vegetation. It is thus very variable: in some years, ever, on first encountering a species have a speci- a species might not fruit at all, whereas in ‘good’ men checked by an expert. It must be realised that years, fruiting may be extensive. It follows that an even widespread species (e.g. Laccaria spp.) may

# RPS Group plc and Scottish Natural Heritage 2005. 272 11 FUNGI

require a microscope to identify them and there- fact include the fruiting bodies of several distinct fore the help of a specialist should always be con- individual mycelia. The number of such individuals sidered. Grouping into species complexes could appears to decrease as the age of the vegetation in be one way of dealing with such common and wide- which they are found increases. spread fungi, and this would allow monitoring to Counts can be made in a number of different proceed without any loss of accuracy. ways (Section 11.2); monitoring for species of con- With the peculiarities of fungal life strategies and servation interest will generally involve a combina- the necessity of having at the present time to iden- tion of these methods. tify the taxa by reference to the fruiting body, these organisms are a special case; they are not the same as 11.2 GENERAL METHODS plants and must not be considered so. However, every effort must be made to tailor existing survey Table 11.1 summarises the methods available for and monitoring activities to the fungal recording surveying and monitoring fungi. process, always bearing in mind the differences between the organisms. You should endeavour to 11.2.1 Direct searches marry monitoring of one group with that of another. Principles If a species is restricted to a known area and has 11.1 ATTRIBUTES FOR ASSESSING specific habitat requirements, a simple and reason- CONDITION ably efficient monitoring method is to conduct 11.1.1 Habitat condition periodic searches of the area of suitable habitat and count the number of fruiting bodies. The entire Assessing the area of suitable habitat for fungi is a area of fruiting will indicate the minimum extent method of indirect monitoring that is particularly of the vegetative colony. If the entire area can be applicable to those species with specialised habitat searched at one time, the number of fruiting bodies requirements. For example, Tulostoma niveum,aUK can be taken as an estimate of the total population BAP Priority Species, is restricted to dense patches size or area covered by the mycelium or mycelia, of moss on limestone boulders and is found in only which can then be compared with data from other a very few localities in Scotland; the extent of years. If the site is too large to be completely cov- habitat at this site can be accurately assessed and ered by one survey, counts should be made for a set mapped. Quantifying the extent of potential habi- duration or along a set route or area (Sections tat enables subsequent monitoring effort to be 11.2.2 and 11.2.3). targeted efficiently. The survey should be timed to coincide with the For general methods for monitoring habitat period of maximum sporome production. If this is extent, see Part II. not known, surveys may have to be carried out on a more regular basis (e.g. one per week) for one fruit- 11.1.2 Population size ing season to identify the period of maximum sporome abundance. However, this may itself vary Counts of the number of fruiting bodies are the from year to year depending upon weather condi- only way by which we can arrive at some idea of tions. A knowledge of the ecology of the target population size in the field, although there are species is required if the fruiting period has to be problems with this approach (see above). With predicted in advance when planning a survey or ectomycorrhizal fungi, a very small area on a tree monitoring programme. root may produce many more fruiting bodies than a mycelium that is colonising many more roots and Field methods is therefore more widespread. Counting the fruit- The area of suitable habitat should be searched ing bodies in as small an area as 2 m Â 2 m may in thoroughly for fruiting bodies of the target species. New sites may be overlooked Affected by spatial as well as temporal variations in fruiting Searching may be less thorough as longer distances must be covered Requires initial outlay on equipment cally targeted to individual species sity to be estimated sity to be estimated; covers larger areas with greater efficiency Provides permanent photographic record; can be used to accurately reposition permanent quadrats Expertise required Advantages Disadvantages Identification Enables den- Identification Enables den- Identification; photography skills Low Identification Can be specifi- can be affected by quadrat size cies may be overlooked Distortions can be caused if photographs of quadrats are not aligned properly Good if whole area can be comprehensively searched Reasonable Cryptic spe- photo- graphs are of sufficient quality used for conspicuous species with restricted distribution spicuous species Reasonable Good if Population size data Efficiency Precision Bias Estimate Good when Estimate Reasonable Reasonable Estimates Estimate Good for con- Presence– absence Estimate of population size Recom- mended species group Scarce species with discrete habitat areas Species found over narrow area Species found over wide area Scarce species with discrete habitat areas Methods for surveying and monitoring fungi Table 11.1. Direct searches Quadrats Transects Fixed-point photography

273 274 11 FUNGI

It will often be worthwhile to record the condition environmental variables. Analysing data to identify of any sporomes found (i.e. fresh or moribund) actual changes in population size is thus not possi- (Fleming et al., 1998), particularly if repeat surveys ble in the short term. Five- to 10-year means of are to be made in the same season; this will allow annual count data should be calculated once estimates to be made of the lifespan of the regular monitoring has been established, and sporomes. continued for several years. If methods are standar- Trampling has been shown to reduce fruiting, so dised, trends can be analysed statistically by searches should be undertaken with caution. If using techniques such as regression. If resources logs have to be moved for any reason they should are not available to undertake annual counts, the be replaced in their original position. accurate identification of population trends For rarer species, the locations of sporomes can becomes more difficult, because variations due to be mapped or marked so that follow-up surveys can the environmental effects on fruiting are harder to be made of the same areas. This will allow assess- adjust for. ments of range expansions and contractions to be made. Sporomes can be marked with Indian ink to 11.2.2 Quadrats ensure that the same sporome is not recorded more than once. Some fruiting bodies last for a Principles comparatively long time, whereas others disappear Quadrats can be used to delineate known areas of after a few days. Recording the lifespan of sporo- suitable habitat for searching. The selection of mes allows the measurement of the longevity and quadrat locations is covered in Section 10.5 and in biomass of a fungus (Richardson, 1970). Fixed-point Part II, Sections 5.3.2 and 5.3.3. Searching a defined photographs (Sections 11.2.4 and 6.1.4) can also be area enables more population parameters to be taken as an aid to future monitoring. estimated, such as sporome density. For species of Although searches should concentrate on areas high conservation interest, permanent quadrat in which species of interest are known to exist, one locations in areas where the species is known to should also spend some time searching outside the occur should be used. However, some effort should currently known population boundary so that be spent on searches outside these quadrats; broader-scale range expansions (or previously because fruiting is very variable, the selection of undiscovered colonies) can be identified. permanent quadrat locations on the basis of short- The keeping of species lists should be encour- term data may omit colonies that were not fruiting aged, as information on fungal associations is limi- when the quadrats were initially chosen. ted; there may be cohorts of species that might be Quadrat size depends on the uniformity of vege- recognised and used as indicators of rare species tation and the species of fungus under considera- that have yet to be recorded on a particular site. tion. Ectomycorrhizal fungi in normal arborescent New species for a site can often be added, since communities can be monitored with 5 m Â 5m many are very sporadic fruiters. plots, whereas 2 m Â 2 m plots are adequate in Surveying should be carried out over other peri- plantations (Richardson, 1970). On cliff tops and ods of the year as well as the generally accepted mountain tops with dwarf willows (Salix spp.), survey time of autumn. Some ectomycorrhizal 2mÂ 2 m plots are also sufficient. In very variable fungi will fruit from May until the first frosts. arborescent communities, 50 m Â 50 m or even Good monitoring cannot be achieved by a casual 100 m Â 100 m plots split into four equal units visit to an area in autumn only. Essential field have been shown to be necessary. Even in seemingly equipment is listed in Appendix 6. uniform communities, the variation therein should be carefully scrutinised. Lange (1982, 1984, 1991) Data analysis and interpretation used 2 m Â 2 m plots in studies of fruiting periodi- The extent of sporome production will vary greatly city. In woodland systems, 2000 m Â 2000 m plots from one year to the next according to changes in have been used (Lange, 1993). 11.2 General methods 275

Quadrats can be used to study hypogeous (truffle- like) fungi, which may be first located by animal 11.2.3 Transects diggings (such fungi are dispersed by being eaten Principles by rodents, pigs, etc.). If piles of dung are taken as Transects for monitoring fungi can be used to cover the equivalent of quadrats then coprophilous fungi larger areas more efficiently than is possible with can be monitored, although the timescale of moni- direct counts or quadrats. They are more suitable toring must be much reduced. At least one rare for species that occur over a wide area and thus are macromycete occurs on dung. Moss cushions and less efficiently monitored with direct searches or other small areas of habitat such as tree stumps or permanent quadrats. fallen trunks could also be treated as permanent Transect locations for monitoring fungi will gen- quadrat units. erally be permanent. It is possible to use distance See Section 11.2.1 for the principles of fungal estimation methods (measuring or estimating monitoring, which apply to all methods covered the distance from the transect line to each in this section. sporome) and hence use computer software such as Distance for estimating density (Section 10.6). Field methods Alternatively, you can search for sporomes within The marking of permanent quadrats is discussed in a fixed distance of the transect line and calculate Appendix 5. Care should be taken not to disturb or densities from this (Section 10.7). damage the surrounding community when record- See Section 11.2.1 for the principles of fungal ing quadrats: this may have adverse effects on the monitoring, which apply to all methods covered species being monitored. Trampling has been in this section. shown to reduce fruiting, so setting up quadrats should be undertaken with caution. If logs have to be moved for any reason they should be replaced in Field methods their original position. Trampling has been shown to reduce fruiting, so Quadrats should be set out in a line or along a setting up transects should be undertaken with transect, or randomly located in grassland or simi- caution. If logs have to be moved for any reason lar habitats if the species is distributed over a small they should be replaced in their original position. area. The area of the quadrat should be carefully The transect should be walked along a standard searched, and the numbers of sporomes and their route while surveying the immediate area for sporo- condition recorded (see Section 11.2.1). mes. The number and condition of sporomes Quadrats can be photographed by using fixed- should be recorded. The perpendicular distance point photography (Section 11.2.4); this provides a from the transect line to each sporome can be useful permanent record of the condition of the measured, or a strip of fixed width can be searched surrounding habitat as well as the number of sporo- (e.g. 2 m on each side of the transect line). Quadrats mes. Recommended field equipment is listed in (Section 11.2.2) can also be set along the transect. Appendix 6. Transects should be timed to coincide with the maximum period of sporome abundance, unless Data analysis and interpretation there are sufficient resources available to survey As discussed earlier (Section 11.2.1), natural fluctua- on a regular basis throughout the year. tions in the abundance of sporomes make the correct Transects designed for recording fungal fruiting identification of trends in population size proble- bodies should be used for other or parallel monitor- matic. Five- or 10-year means of sporome counts or ing activities, because the time of fungal fruiting densities calculated from quadrat data should be will not be known exactly. Therefore, the longer used to identify trends. If appropriate sampling is the window of search time the better. used, data can be analysed statistically by using stand- Fixed-point photography (Section 11.2.4) can also ard tests (Part I,Section2.6.4 and Appendix 4). be used to make a permanent record, which can be 276 11 FUNGI

useful for assessing successional changes that may Briefly, a camera tripod is set up at a fixed influence the abundance of sporomes. The neces- point, which is marked so that it can be precisely sary field equipment is listed in Appendix 6. relocated on subsequent visits. Photographs are taken at a fixed angle and height, with the camera Data analysis and interpretation settings (aperture, film speed, etc.) kept constant As discussed earlier (Section 11.2.1), natural fluc- from year to year. tuations in the abundance of sporomes make the The locations of individual sporomes can be correct identification of trends in population size traced from photographs on to acetate sheets to problematic. Five- or 10-year means of sporome facilitate comparisons of photographs from differ- densities calculated from transect data should be ent years. Field equipment requirements are listed used to identify trends. If appropriate sampling is in Appendix 6. used, data can be analysed statistically by using standard tests (Part I, Section 2.6.4). Data analysis and interpretation As discussed earlier (Section 11.2.1), natural fluc- 11.2.4 Fixed-point photography tuations in the abundance of sporomes make the correct identification of trends in population size Principles problematic. Five- or 10-year means of sporome Fixed-point photography is a useful technique for numbers per photograph or densities calculated assessing successional changes, marking fruiting by using the size of area enclosed by the photo- bodies to determine longevity and studying grazing graphs should be used to identify trends. If appro- factors. It is especially suited to species such as priate sampling is used, data can be analysed moss cushion inhabitants (e.g. Galerina spp. and statistically by using standard tests (Part I, Tulostoma niveum). Section 2.6.4). The photographs can be used to create overlays, which can be compared with those from other years to assess changes in sporome abundance and distri- 11.3 FUNGUS CONSERVATION bution. They can also be useful to assess successional EVALUATION CRITERIA changes in the surrounding vegetation, which may 11.3.1 Key evaluation considerations be influencing the distribution of sporomes. If possible, all associated organisms should be There are about twelve thousand fungus species recorded by the generalist; at present, there is a (including the slime moulds) in the UK but the lack of information on fungal associates, which distribution of fungi is much less well known needs to be addressed. It was only because of care- than that of other groups of vascular and non- ful monitoring and observation that the full asso- vascular plants. As fungi are recognised by their ciation of certain species of disc fungi with species fruiting bodies, which are present only at certain of moss and liverwort was discovered. times of the year and are unpredictable in their See Section 11.2.1 for the principles of fungal occurrence, they are difficult to record effectively. monitoring, which apply to all methods covered Thus the distributional data are, on the whole, too in this section. scanty to produce lists of scarce or rare species to be assembled (Hodgetts, 1992). The current British Field methods checklist of basidiomycetes is due for completion Fixed-point photography methodology is covered and the checklist for ascomycetes is in need of in detail in Part II, Section 6.1.4. Although more revision. Work is under way to produce distribu- concerned with large-scale monitoring, the tech- tion data for certain fungus groups, which are niques of fixed-point photography described being developed as a component of the National therein are straightforward to adapt to monitoring Biodiversity Network Species Dictionary Project species such as fungi on a small scale. ( JNCC, 2004). 11.3 Fungus conservation evaluation criteria 277

The British Mycological Society (BMS) (webpage: mycological interest and advising on conservation www.britmycolsoc.org.uk/) was founded in 1896. measures. The Society is active in the promotion of conserva- The ABFG, working with Plantlife and English tion and field mycology, and established the BMS Nature, has been involved in funding current con- conservation group in 1996, part of the Fungus servation programmes and the preparation of the Conservation Forum. The conservation group’s Conservation of Wild Mushrooms Code of Practice. focus is to promote all issues related to fungus Several species of fungi are edible, and ‘picking for conservation, including involvement with the the pot’ is a common pastime. Overpicking of wild inclusion of fungi in the Bern Convention; the UK mushrooms and other fungi is becoming a pro- Biodiversity Action Plans for fungi; the UK blem, and a Code of Practice has been developed ‘Important Fungus Areas’ report (see site designa- to help tackle the problem and give advice to mush- tion criteria below); the British Basidiomycete room pickers. The code can be found at Checklist and the revision of the UK Red Data List www.bms.ac.uk/Code.html. for fungi. Affiliated to the BMS as part of the BMS A number of surveys are currently being run. Recording Network there are Local Fungus Groups The Pink Waxcap Survey is a joint initiative of (LFG) that now exist in many parts of the country. Plantlife, the British Mycological Society, the These can be found on the webpage that has been Association of British Fungus Groups and the set up for the LFG (www.britmycolsoc.org/LFG/ RSPB. The Pink Waxcap Hygrocybe calyptriformis is index.html). The BMS has set up, in consultation listed under the UK Biodiversity Action Plan and is with other organisations in the British Isles, a part of Plantlife’s Back from the Brink programme, Fungal Records Database (BMSFRD), which cur- supported by English Nature, Scottish Natural rently contains over 600 000 records of fungi. Heritage and the Countryside Council for Wales. There is a checklist of British fungi and also a list The survey also includes the Parrot Waxcap that contains links to over 2000 distribution maps Hygrocybe psittacina and the Blackening Waxcap of various species. The maps show 10 km squares Hygrocybe conica. The Countryside Council for for which there are records in the BMSFRD. The Wales is currently undertaking a survey of grass- BMS is also developing a British Fungal Portal, land fungi throughout Wales. The Environment & which aims to create a pioneering integrated access Heritage Service is organising a survey of Waxcap system for information on British fungi, building Grasslands in Northern Ireland and aims to survey on the voluntary activities of all sectors of the com- all the 10 km squares in Northern Ireland looking munity. One of its functions is to improve imple- for the best waxcap sites in each. SNH funded a mentation of current Biodiversity Action Plans for survey of stipitate hydnoid (‘tooth’) fungi in fungi, facilitate their development, and promote Scottish pinewoods (Newton et al., 2002) and a wide-scale conservation activities. grassland fungus survey (Newton et al., 2003). The Association of British Fungus Groups (ABFG) (webpage: www.abfg.org/) was founded in 1996. It 11.3.2 Protection status in the UK and EU acts as a national organisation for field enthusiasts who are interested in learning more about fungi, No British fungi are listed in Annex I of the Bern and recording fungi for local and national data- Convention or in Annex II of the Habitats and bases. The Association includes a nationwide net- Species Directive. The proposal to add 33 species work currently including 26 member groups and of fungi (not all of which occur in Britain) onto individual members (these can be found at Annex I of the Bern Convention has been www.abfg.org/groups.htm). It is closely involved withdrawn. in the conservation of fungi in the UK, working Four species of British fungus are listed in closely with Plantlife as a member of the Fungus Schedule 8 (scheduled in 1998) of the Wildlife & Conservation Forum. The ABFG also work with Countryside Act 1981. The species are Sandy Stilt other organisations surveying sites of potential Puffball Battarraea phalloides, Royal Bolete Boletus 278 11 FUNGI

regius, Oak Polypore Buglossoporus pulvinum and Guidance for Lower Plants is still under develop- Bearded Tooth Hericium erinaceum.Twenty-sixspecies ment. Information on the Guidance can be found are listed in Section 74 of the Countryside & Rights on the JNCC webpage www.jncc.gov.uk/csm/ of Way Act 2000 as species of principal importance, guidance. though only the above four species have full The Important Fungus Areas (IFAs) report by protection. The species listed under Schedule 8 can Plantlife, the British Mycological Society and the be found on the JNCC web page www.jncc. Association of British Fungus Groups, helped with gov.uk/page-2126 and those in Section 74 at funding by English Nature, the Countryside Council www.defra.gov.uk/wildlife-countryside/cl/habitats/ for Wales and Environment & Heritage Service, has habitats-list.pdf. now produced an interim list of over 500 sites of The twenty-six species listed in Section 74, plus great significance for fungi in England, Wales, the Black Falsebolete Boletopsis leucomelaena, are cur- Scotland and Northern Ireland. One major problem rent Priority BAP species. The species and their in the conservation of fungi has been the lack of Biodiversity Action Plans can be found on the UK criteria against which a site could be assessed as to BAP web page www.ukbap.org.uk/fungus.htm. its mycological importance. The object of this project was to build up a database of sites considered to 11.3.3 Conservation status in the UK be important for fungi by mycological recorders and to derive criteria against which sites could be The Red Data Book for UK macrofungi and some assessed (Northern Ireland Fungus Group, microfungi is due for completion in 2004. There is undated). This interim list of IFAs will help target no equivalent for Ireland as yet but the develop- conservation efforts to ensure that key sites get ment of a Red Data List for fungi in Ireland has been proper protection. The criteria are as follows. recognised as a Lower Priority or long-term additional work under Target 2 of the Plant Diversity CRITERION A: The site holds significant Challenge ( JNCC, 2004). Currently 38 fungi species populations of rare fungal species, are classified as extinct, ten as critically endan- which are of European, or UK gered, 63 as endangered, 95 as vulnerable on the conservation concern. A site IUCN list (designated 1998), and one as near threat- should be considered if it includes ened in the GB Red Data list. at least five species from: the provisional UK Red Data List 11.3.4 Site designation criteria (1992), UK Biodiversity Action Plan and/or Schedule 8 or the European Very few nature reserves have been set up to Red Data List (A & B) and/or Species conserve fungi in Great Britain and Ireland. SSSI of European Concern (Bern criteria for designating sites for fungal interest Convention proposals) are described by Hodgetts (1992), which can be CRITERION B: The site has an exceptionally rich found on the JNCC web page www.jncc.gov.uk/ and well-recorded mycota in a UK publications/sssi/sssi_content.htm. In brief, the context. A site should be presence of colonies of Nationally Endangered, considered if it has at least 500 Vulnerable or Rare species as classified by the Red recorded species Data Book are eligible, although only strong colon- CRITERION C: A site that is an outstanding ies of Vulnerable and Rare species may be eligible. example of a habitat type of The Common Standards Monitoring (CSM) known mycological importance Guidance has now been produced by JNCC. It pro- CRITERION D: A nominated site that is vides guidance on the identification of inter- considered to be important but est features, attributes, targets and methods of for which further information assessment for species on designated sites. The is needed 12 * Lichens

The principles behind lichen survey and monitor- in substrate pH and changes in management prac- ing techniques are basically identical to those for tices. Severe weather conditions (e.g. drought, cold) other groups of lower plants. However, there are can also be detrimental to lichens. A scarce lichen some considerations peculiar to lichen survey and on a particular tree is probably doomed if the tree monitoring, which must be considered when dies or falls over. designing a suitable programme. This extreme sensitivity to environmental Many species of conservation importance are change, coupled with the scarcity of suitable very scarce; some are known from only a single habitat for many rare lichens, means that any site. In the case of lichens, a single site can be survey and monitoring programme must consider something as small as a single tree, a rock or a the condition of the surrounding habitat as well tree stump. Many species are relict, and under as the health or size of the lichen colony itself. If prevailing conditions cannot colonise new habi- monitoring does not include this component, tats. The sites themselves may be small relics of then a species may well be lost before any remed- larger areas of ancient habitat with long con- ial action can be taken. Transplanting lichens tinuity and a history of minimal adverse disturb- can be carried out if an isolated colony is in ance.Thusthenecessaryconditionsinwhich serious danger. For example, lichens growing on the species can persist may only occur in one Beech Fagus spp. (which has a relatively short location or in a series of distinct fragments. By lifespan for a tree) may need to be moved to definition, a relict species cannot colonise dis- younger trees when their current host tree dies tant sites even if conditions are suitable. The to prevent the species from dying out. Such destruction of ancient, unrecreatable habitat is transplants must only be carried out after expert an important cause of lichen rarity, but far from consultation. the only one. Another consideration that must be taken into Other lichens rely on extremely localised habi- account is that the identification of lichens, par- tats. For example, Gyalideopsis scotica requires decay- ticularly in the field, requires much specialist ing bryophyte material on specific soils near the knowledge. Although some species are conspicu- summits of a few Scottish mountains. Cladonia ous and reasonably distinctive, many others are botrytes grows on dead pine (Pinus spp.) stumps at a extremely difficult to identify, and others can only particular stage of decay. be separated from related species in the labora- Lichens may therefore require ephemeral scarce tory. Monitoring such species will therefore habitats or ancient scarce habitats; in either case, require expert assistance. Unfortunately, it may their habitat requirements are often very specific not be possible for generalist field staff to under- and any alteration of the conditions under which take lichen surveys and monitoring themselves lichen species will grow will frequently adversely for those very species that most urgently need to affect the health of the colony. Most species are be monitored. In this case, expert advice will have extremely intolerant of shade, pollution, changes to be sought.

# RPS Group plc and Scottish Natural Heritage 2005. 280 12 LICHENS

12.1 ATTRIBUTES FOR ASSESSING monitoring is essential; species can quickly be CONDITION lost if habitat conditions become unsuitable. Habitat monitoring is not strictly within the 12.1.1 Habitat condition scope of this chapter. However, because habitat Lichens often grow in very localised and specific condition is so crucial to the persistence of lichen habitats; it is therefore essential that the general colonies, a brief discussion of the factors that may habitat condition be assessed on every monitoring need to be monitored is given. For further informa- visit. If the habitat is deteriorating, recognising tion, see Part II for general habitat monitoring this will give advance warning of a subsequent methods. deterioration of the health of the lichen colony and will provide more time for remedial action Field methods to be taken. The field methods will vary depending on the habitat of the lichen species in question. Factors that may need to be considered and monitored will 12.1.2 Colony numbers include the following. Lichens generally grow in discrete colonies. * Pollution: local industrial pollution, brickwork A count of the number of colonies is therefore and quarry dust, power station emissions, agricul- a simple indication of the status of a species. tural pollution, waste disposal. Monitoring the number of colonies can give an * Habitat destruction by natural causes: windblow indication of population trends. of trees on to colony, death of substrate tree, mollusc grazing. 12.1.3 Colony size * Increased shade: increased canopy, shrub layer (particularly Holly Ilex spp. and Rhododendron Assessment and monitoring of the size of a lichen Rhododendran ponticum), Ivy Hedera helix invasion, colony will give a straightforward indication of the basal shoot growth, Bracken Pteridium aquilinum health of that colony. Expansions or contractions and Bramble Rubus fruticosus agg. invasion, leaf of colonies can be monitored and related to litter. changes in habitat condition, especially where a * Changes in grazing regime and other manage- remedial conservation exercise has taken place. ment practices. * Changes in substrate pH and other chemical prop- 12.2 GENERAL METHODS erties (e.g. nutrient status). . Table 12.1 summarises the general methods for Refer to Part II for details on the monitoring of surveying and monitoring lichens. these factors.

12.2.1 Habitat condition Data analysis and interpretation Data analysis will depend upon the factors being Principles monitored. For basic monitoring of habitat condi- As mentioned previously, the habitat requirements tion (e.g. health of tree), a subjective assessment of of lichens, particularly those species that are change will probably be sufficient provided the scarce, are very specific. Any change in the sur- suitable habitat condition is properly understood. rounding environment of a lichen colony can The use of an intelligent eye to assess all change is therefore have detrimental effects. Useful informa- desirable. The change that could be most damaging tion for lichen conservation can be gathered by to the colony might not be one that was thought of monitoring their habitat. For those species that when the monitoring scheme was first put in are restricted to very few locations, habitat place. Colonies must grow on more or less two-dimensional surfaces. Species from ephemeral habitats may disappear from permanent quadrats, requiring repeat surveys to find new colonies. Does not in itself monitor the health of a colony directly Can be time-consuming; requires intial outlay on equipment quantitative data with little expensive equipment Quick and easy method for monitoring the potential health of a colony Provides permanent pictorial record; can be used to accurately reposition permanent quadrats Identification Provides Ability to judge whether changes in habitat will be detrimental to lichens Identification Photography Expertise required Advantages Disadvantages cover and frequency affected by quadrat size Not applicable can be caused if photographs of quadrats are not aligned properly Good Estimates of applicable Reasonable Good Distortions Good for species with few colonies Good Not Frequency Cover Estimate of colony number Presence– absence Cover absence applicable Presence– Not Population size data Efficiency Precision Bias All, but particularly useful for scarce species with discrete habitats All All Recommended species group Methods for surveying and monitoring lichens Fixed-point photography Quadrats Table 12.1. Habitat condition

281 282 12 LICHENS

For variables that require quantitative assess- For monitoring large lichens (e.g. lichens of ment such as pH, changes from the monitoring the genus Cladonia, section Cladina, which grow on baseline of ideal condition can be analysed statistic- dune systems) a quadrat of 1 m Â 1 m divided into ally by using standard tests, provided that appro- 16 sections will be an appropriate size. Presence or priate sampling has been used. absence of species within each section can be The susceptibility of lichens to changes in recorded, or cover estimates made. For smaller habitat condition may not be fully understood. species a 25 cm Â 25 cm quadrat will be more If this is the case it may be difficult to establish appropriate. what level of change is acceptable (for example, how much does pH have to change before lichen Quadrat positioning and fixing health is affected?). Monitoring of habitat condi- For lichens that grow on a horizontal surface, the tion should therefore be closely correlated position of the quadrat can be fixed with a peg, with monitoring of the health of the lichens which is a known distance from a buried transpon- themselves. der. A tape run from the transponder to the peg will Changes in habitat condition that are thought locate it and fix its alignment. Final adjustments to likely to lead to detrimental effects on the lichens the position of the quadrat should be made by con- should be acted upon before the effects on the sulting previous fixed-point photographs (Section lichens become serious. 12.2.3). For lichens on a vertical surface, the quadrat can 12.2.2 Quadrats be suspended from a fixed peg. Certain adhesives (and the leachate from them) such as Araldite can Principles be toxic to lower plants; the peg should therefore The principles of quadrat sampling are covered in be fixed at some distance above the colony being Section 10.5. Most quadrat monitoring of lichen monitored. colonies will involve permanent quadrats; many Where the quadrat is at an angle, a fixed point rare species do not spread or colonise new areas. (e.g. an inert screw) can be placed within the study Some species that colonise ephemeral habitats area so that exact positioning of the quadrat can be may not be suitable for monitoring with perman- achieved. ent quadrats, but even if a particular site may not The potential toxicity of materials used for mark- last for long it can be monitored with quadrats ers should be considered. Brass markers should located in the same place for the duration of the not be used; the leachate from brass is toxic to a colonies’ persistence. range of saxicolous bryophytes, and there is a high As well as the quadrat colony of the lichen under probability that it will affect lichens as well. Totally observation being recorded, a search should also be inert materials must be used where any leachate made for the presence of the lichen in other nearby might affect the lower plant communities beneath: areas. Habitat condition (Section 12.2.1) should also stainless steel or a hard, inert plastic could be be recorded. appropriate. Great care must be taken not to disturb the colonies during the recording process. This applies Field methods particularly to species that grow on fragile sub- Quadrat size strates. Also, the quadrat itself should never be Quadrat size should be related to the size of the left in situ; this will frequently affect the growth of lichens that occur within the colony being sur- the lichens underneath it. veyed. Some lichens are large, whereas others are less than half a millimetre in diameter. It is there- Data recording fore important to select a practical quadrat size Presence–absence of species in each quadrat div- with a practical subsection size. ision can be recorded. Alternatively, cover estimates 12.2 General methods 283

can be made, although this can be more accurately data recording (Section 12.2.2). In general, you achieved with fixed-point photography (Section should take three photographs per sample point; 12.2.3). In addition, notes should be taken of the one of the quadrat itself in close-up, one of the number and size of colonies, their height from the quadrat and its immediate surroundings, and one ground and aspect, and their health. Lichen health of the area as a whole so that small- and large-scale can be recorded by noting necrotic patches and changes in the habitat can be assessed. discoloration of the thallus. Any change in the number of fruits of fertile species should also be Field methods recorded. Sites such as trees with colonies can be Methodology for fixed-point photography is cov- discreetly tagged to aid relocation on subsequent ered in detail in Part II, Section 6.1.4. A heavy-duty visits. tripod should be used, and as diffuse a light as Except for a few ephemeral species, there is no possible should be obtained. Photography is best main season for recording lichens. However, carried out when the sky is overcast; heavy or sharp lichens are more easily seen when damp, and shadows can often render photographs useless for woodland species are much more easily seen comparing with previous photographs. when there are no leaves in the canopy. Weather When photographing quadrats, it is important conditions permitting, with the exception of high- to have a second quadrat for the photograph, of level Arctic–alpine species, the months from identical size to that used for recording, which is November to April are probably best. undivided and therefore casts less of a shadow. For most species, monitoring should be carried The shadow from a divided quadrat will obscure out every three years, but a brief check every year the lichens and make analysis difficult at a later to ensure that no catastrophic change is occurring date. If the camera and tripod settings are noted is desirable, particularly for rare species with few and repeated exactly on each visit, a permanent sites and epiphytes. Essential field equipment is ‘quadrat’ can be obtained without the need for a summarised in Appendix6. quadrat to be physically placed over the lichens. For details of such an approach carried out for Data analysis and interpretation corticolous and saxicolous lichens, see Perkins & Providing that appropriate sampling has been Miller (1987a,b). used, changes in frequency can be examined statis- Photographs should be taken at similar times of tically by using standard tests (Part I, Section 2.6.4). year so that surrounding species are in a similar Decreases in cover or frequency will probably be stage of development in each photograph. correlated to a change in an underlying habitat As well as photographing the quadrat itself in variable (Section 12.2.1). Correlation or regression close-up, it is also important to monitor the can be used to examine these relations, and the immediate area by recording the quadrat within results can be used to suggest remedial action that its surroundings. This will greatly assist the identi- may need to be taken to reverse any decline. fication of changes to the habitat that may have affected the lichens in the quadrat. A photograph 12.2.3 Fixed-point photography of the habitat within a few metres as well as a broader-scale photograph taken with a wide-angle Principles lens is ideal. A macro lens will normally be essen- Fixed-point photography is an invaluable method tial for close-up photographs of the quadrat. Slide for monitoring lichen communities. Photographs films provide better definition than print films, provide a clear unequivocal record of the condition although prints are more useful for annotating in of a lichen colony and its surrounding environ- the field; there is perhaps a case for using two ment, and useful data such as cover can be derived cameras to record in both media if resources are from photographs. They also provide a means of available. The necessary field equipment is listed in precisely relocating and realigning quadrats for Appendix 6. 284 12 LICHENS

nitrogen-based alkaline pollutants have taken the Data analysis and interpretation place of industrial effluent gases in the atmos- Diagrams showing the position and size of the phere, and this is having a marked effect on colonies can be traced from the quadrat photo- lichens. Heathland species are suffering from inva- graphs and used as overlays. Areas of colonies can sive competition by aggressive higher plants of be calculated by using a grid overlay. Provided that the habitat. The associations of species that grow appropriate sampling has been used, the change in on trees are also changing. The bark of mature areas between years can be analysed statistically by trees in urban areas has been so impregnated by using standard tests (Part I, Section 2.6.4). sulphur dioxide over the years that it remains acid. If slide film has been used, A3 prints can be To assess the effects of alkaline pollution from car made with colour copiers. Quality can vary; only exhausts and intensive farming practice, the assem- the higher-quality photocopiers give results of suf- blage occurring on twigs and young branches is ficient detail at A3 from a 35 mm slide. studied; this has shown considerable change in recent years. There are few groups of organism that are as 12.3 LICHEN CONSERVATION useful for studying the health and antiquity of EVALUATION CRITERIA habitats as lichens. Since the work of Dr Francis 12.3.1 Key evaluation considerations Rose on the link between the presence of a suite of lichen species and ecological continuity in wood- Lichens occur in a wide variety of habitats. In woodland started in 1974, much work has been done in land, they may be present on the bark, twigs, leaves formulating lists of lichens that can be used for and dead wood of the trees. They occur on both assessing ecological continuity. Rose published man-made and natural rock outcrops. Some species two lists of lichens for this purpose. The first was occur on compacted soil and others live on dead a list of 30 indicator species, which was used to and decaying bryophytes. On coastal shingle, establish the Revised Index of Ecological lichens colonise the pebbles and the sand between Continuity (RIEC) for a wood. This index was calcu- the pebbles as well as detritus which accumulates lated as a percentage of the 30 species, based on a from dead vegetation. Some, such as Xanthoparmelia formula in which the number of species present mougeotii, will grow quite happily on glass, and it is was used to calculate a percentage of a wood with a not unusual to find several species on older cars. hypothetical perfect ecological continuity. The pre- Pieces of old leather on the beach are a habitat for sence of twenty species gives an RIEC of 100%. several very rare species, and the lichens of mine A theoretical wood with all thirty would have an spoil contaminated with heavy metals are a study RIEC of 150%. Some of our very best woods have in themselves. Churchyards are a rich source of been found to have an RIEC of more than 100%. lichens as they provide a wide variety of habitats. This index is particularly useful in assessing the St Brelade’s Church in Jersey holds the record num- conservation value of a wood. ber of lichen species for any individual churchyard: In 1992, the New Index of Ecological Continuity at the latest count, 206 species had been recorded. (NIEC) was published. This is a list of 70 species and Lichens are highly sensitive to the state of their is designed to assess ecological continuity. The habitat, and will disappear fast if conditions cease NIEC is simply the number of species on the list to be favourable. This fact was used to assess con- that are present. The NIEC list of lichens contains centrations of sulphur dioxide in the atmosphere; species that are more difficult to identify, and the resulting maps gave an accurate indication of therefore the index is designed for use by the zones of pollution throughout the UK. Since the more experienced lichenologist. Woods with a collapse of Britain’s industrial base some twenty high degree of ecological continuity are likely years ago, sulphur dioxide concentrations have to support rarer species, and this is taken into declined dramatically. However, in recent years account in that bonus species may be added to 12.3 Lichen conservation evaluation criteria 285

the NIEC number to give a ‘T’ NIEC number. Sites The NIEC is now used for woodland in England, with a ‘T’ NIEC number of more than 30 are con- in Wales except for the area where the ESIEC is sidered to be of high conservation value for appropriate, and throughout most of Ulster and lichens. Those with fewer than 20 are likely to the Republic of Ireland. It may be used in conjunc- be of limited importance. However, in the south- tion with the EuOIEC in western, upland parts of east and eastern parts of England, woods with these areas. lower NIEC numbers may have greater conservation A similar list of indicator lichens has been sug- importance. gested for the assessment of continuity by using Recently, it was found that certain NIEC species saxicolous species growing on old buildings and held little significance as indicators of continuity in churchyards. This list was published in the in certain parts of the UK. Species such as Lobaria Bulletin of the British Lichen Society provisionally pulmonaria, whose presence is highly significant by Rose, but is not yet widely used. Similar indices in Sussex, are virtually ubiquitous in Western could be made for use in assessing ecological con- Scottish woodlands. Coppins & Coppins (2002) tinuity in heathland, well-established bryophyte- have provided the most up-to-date list of lichen and lichen-dominated calcareous grassland, stabil- indices, building on the NIEC and RIEC developed ised dune systems and land contaminated by heavy by Rose. These indices include the following. metals. As has been already stated, lichens associate Western Scotland Index of Ecological Continuity closely with very specific ecological parameters. (WSIEC) They can therefore be used to assess the nature of This index is used in Western Scottish Highlands. the substrate on which they are growing. Various It is a baseline list of fifty species to which notable geologies with a variety of climate, altitude and bonus species may be added. latitude all have their specific lichen floras. The lichens of the Arctic–alpine regions of Britain have Eu-Oceanic calcifuge Woodland Index of been well studied by a small but dedicated group of Ecological Continuity (EuOIEC) energetic lichenologists. Lichens also grow in a wide This index is used mostly for oak-dominated wood- range of coastal situations, and a few are even inter- land in more upland and exposed situations in tidal. There is also a lichen flora of unpolluted Western Britain. It has a base list of thirty species streams, rivers and lakes. Thus lichens may be to which notable bonus species may be added. used by competent lichenologists to establish the nature, continuity and health of a great variety of Eastern Scotland Index of Ecological Continuity habitats, both natural and man-made. (ESIEC) Many lichens are known to be slow-growing and This index is used in eastern Scotland as well as in to live for extremely long periods of time. This has the England–Wales border country. It consists of been used to age geological events such as rock falls 30 indicator species to which notable bonus species and glaciation. There are also fast-growing species may be added. This index is used for assessing the such as members of the genus Peltigera and Lobaria native pine forests of Scotland. as well as ephemeral lichens. Some lichens are ephemeral in that their fruiting bodies are strictly Western Ireland Index of Ecological Continuity seasonal. Many of the lichens associated with (WIIEC) heavy metal contamination fall into this last This index is used for assessing woodland in the category. extreme oceanic conditions of south-western Ireland. Lichen associations found here have a simi- 12.3.2 Protection status in the UK and EU larity with those of Macronesia. Fifty species are listed, and once again notable species may be No British lichens are listed onI of Annexthe Bern used to establish a ‘T’ number. Convention or in AnnexII of the Habitats Directive. 286 12 LICHENS

Thirty-two species of British lichen are listed on rare internationally, and where Britain holds the Schedule 8 of the Wildlife & Countryside Act 1981. majority or highly significant populations of the Thirty-three species are listed on Section 74 of the species. So far 180 species have been so designated. Countryside & Rights of Way Act 2000 as species of Twenty-eight species are protected under principal importance, although only the thirty-two Schedule 8 of the Wildlife & Countryside Act species listed in Schedule 8 have full protection. 1981. Originally, this consisted of 30 species, but However, the species listings conflict; the most two have been deleted following recommendations recent list of species listed under Schedule 8 can be by the British Lichen Society. See the JNCC website found on the JNCC web page www.jncc.gov.uk/page- for the most recent listings. 2124 and those in Section 74 at www.defra.gov.uk/ The above categories are for threat to, and con- wildlife-countryside/cl/habitats/habitats-list.pdf. servation of, species. British Lichens are also listed by rarity; categories used are Nationally Rare and 12.3.3 Conservation status in the UK Nationally Scarce. Some 63% of the British lichen flora is either Nationally Rare or Nationally Many lichens are very rare and threatened. In 2003, Scarce. A significant number of these are consid- the British Lichen Society published a new Red ered as being of least concern regarding their Data list of lichens. (Woods & Coppins, 2003). This conservation status. Nationally Rare species are supersedes all previously published lists including restricted to between 1 and 15 British ten those prepared by JNCC. kilometre squares. Nationally Scarce species are The following Conservation Categories are used restricted to between 16 and 100 British ten for the threatened species. The numbers given are kilometre squares. The British flora also contains taken from Woods & Coppins (2003). endemic species. Figures for these categories are as follows. Extinct 32 species Critically Endangered 40 species Endangered 30 species Nationally Rare 646 species Vulnerable 106 species Nationally Scarce 525 species Data Deficient 226 species Endemic 32 species Near Threatened 205 species Including possibly endemic 43 species Least Concern 117 species Not Evaluated 79 species Total 1835 species 12.3.4 Site designation criteria

There are still a number of new species waiting to Many sites that are important for lichens will have be described, and many of the parasymbionts and been selected on the basis of habitat or vegetation most lichen parasites are not included. However, types, although some sites, such as woodland with non-lichenised fungi traditionally studied by liche- a distinctive Lobarion pulmonariae lichen associ- nologists, such as Stenocybe, are included. ation, may have non-vascular plants as the major There are also lichens that are the subjects of interest but low vascular plant interest. However, Biodiversity Action Plans. These have been the sub- since 1992 when the SSSI guidelines for non- ject of especially intensive searches by members of vascular plants were published, it has been possible the British Lichen Society. In several cases, this has to designate SSSIs purely for their lichen interest. resulted in a considerable re-assessment of their rar- Several SSSIs now exist where the primary interest ity status. In at least one case, that of Lecanactis hemi- is the lichen flora (Church et al., 1996). sphaerica, the species was found to be a churchyard SSSI criteria for designating sites for lichen variant of another species, Lecanographa grumulosa. interest are described by Hodgetts (1992), which A new category of International Responsibility can be found at the JNCC web page www.jncc. has also been designated. These are species that are gov.uk/publications/sssi/sssicontent.htm. 12.3 Lichen conservation evaluation criteria 287

All sites with viable populations of species listed important assemblage of 200 for most parts of on Schedule 8 of the Wildlife & Countryside Act Britain and 300 in parts of the south-west, Wales, 1981 can be selected for SSSI designation. All Red the Lake District and most of Scotland. Schedule 8 Data Book species’ localities can be considered as species score 200, Nationally Rare 100, and candidate sites. In addition, a scoring system Nationally Scarce 50. The Indices of Ecological for Nationally Rare and Scarce species and species Continuity (see above) can also be used to select characteristic of certain climatic conditions can be ancient woodland and parkland sites for SSSI employed, with a threshold score for a nationally designation. 13 * Bryophytes

Surveying and monitoring bryophytes poses con- establish frequency and to generate broad distribu- siderable problems. Most are so small and difficult tion maps for target species. to identify that anything other than qualitative or at best semi-quantitative data is time-consuming 13.1.2 Population size and expensive to acquire. Some species are difficult to identify even for specialists, and some always Semi-quantitative or quantitative methods will require confirmation with a microscope. Working involve some measurement of extent. For most with bryophytes takes longer than working with bryophytes it is not feasible to count individuals, most vascular plants. Many species grow in associ- because it is never known whether a clump repre- ation with other species, and trying to quantify the sents one individual or many. Species that form amount of a target species can easily cause consid- discrete cushions, mats or turfs can be counted in erable damage to the habitat. these units. Otherwise, area can be estimated and There are very few published studies on survey- treated as an index of population size (the greater ing and monitoring bryophytes in Britain. Most the extent, the healthier the population is assumed monitoring has consisted of merely checking that to be, even if the number of individuals comprising species are still present, with only limited attempts that extent is unknown). at recording population size. Cushion-formers tend to occur in monospecific A feature of some bryophytes is that they may be cushions and are thus suitable for direct counting strongly associated with other plant species. of cushions and area measurement. Some turf- This is obviously true with epiphytic species (e.g. formers can also be monitored in this way, Orthotrichum obtusifolium, which only occurs on trees but others occur in association with other species, with nutrient-rich bark) or Jamiesonella undulifolia, giving rise to the added complication of estimating which is restricted to Sphagnum hummocks. the proportion of the turf occupied by the target species. Similar problems occur with mat-formers; few species form discrete monospecific stands. 13.1 ATTRIBUTES FOR ASSESSING Techniques suitable for long-lived perennial CONDITION bryophytes will rarely be useful for annual or 13.1.1 Presence–absence ‘short-term shuttle’ (see During, 1992) species. Fixed-point photography and permanent quadrats Monitoring of bryophytes has in the past concen- are not suitable for monitoring short-term species trated upon establishing that a species of interest is over time; for these species, presence–absence in still in existence on sites where it has been predefined areas could be used. Populations of ephem- viously recorded. Presence–absence in a series of eral species are often subject to wide fluctuations, samples (e.g. quadrats or transects or individual so the identification of trends may require the cal- host plants for epiphytic species) can be used to culation of at least 5-year means of data.

# RPS Group plc and Scottish Natural Heritage 2005. 13.2 General methods 289

Within the ephemeral group there are species Samples of some species may need to be taken for which the time of year of monitoring may be for later identification by a specialist. This is obvi- critical; for example, those that can only be identi- ously undesirable for rare species, but is unavoid- fied from mature sporophytes or those that may be able for those species that require microscopic inaccessible in winter. analysis to confirm identification. Recommended field equipment is listed in Appendix 6. 13.2 GENERAL METHODS Data analysis and interpretation The general methods for monitoring bryophytes Providing methods are suitably standardised, are summarised in Table 13.1. counts from different years can be compared statistically using techniques such as regression (Part I, 13.2.1 Total counts Section 2.6.4). If individual cushions have been marked and re-found at a later date, estimates can Principles be made of the mean lifespan of a clump. Counting individuals is rarely an option with bryophytes, because most species form turfs, cushions 13.2.2 Visual estimates or mats comprising aggregates of stems, which may or may not be a single individual. Not all of Principles these life forms are discrete, so if some form of Where bryophytes are conspicuous because of quantitative technique is required it is vital from their size, colour or other characteristics, and the outset of monitoring to establish what is to be where the population is relatively large and con- counted. fined to a well-defined site or habitat, visual esti- Counting cushions is an effective way of quanti- mates can be a rapid means of recording frequency fying the amount of cushion-forming species, but or abundance. Within stands that contain the tar- you cannot be sure that each cushion is an individ- get species, it is rare that the species will be suffi- ual. By considering each cushion as a circle, meas- ciently abundant to allow commonly used scales, uring the diameter gives a means of estimating such as the Domin scale, to be used. It may there- total area, but where large numbers of cushions fore be necessary to define a scale that is sensitive occur this can be time-consuming and cause con- enough to reflect the abundance of the target spe- siderable disturbance. cies in all stands. Most visual estimate scales such as the DAFOR Field methods scale are semi-quantitative and involve a certain If the target species is confined to a reasonably amount of subjectivity. It is therefore essential small location, total counts can be made of all the that the scale to be used is clearly defined before individual units in that area. In larger areas, a more monitoring starts, or at least established with a efficient means of estimating numbers can be pilot study when baseline data are being gathered. achieved by using timed counts, transects (Section It will usually be appropriate to make visual esti- 13.2.3) or quadrats (Section 13.2.4). mates within quadrats (Section 6.4.2) in order to The area to be searched should be examined standardise recording techniques. carefully for the target species. Non-ephemerals can be marked with a discrete tag or stake to ensure Field methods that clumps are not counted twice; this will also Making visual estimates of bryophytes is carried enable data to be collected on the longevity of out in a similar manner to that used for vascular individual units. The best method is to mark all plants, with adaptations of the scales used if individuals, cushions or patches and then count required. This is covered in more detail in Part II, the markers. Data on extent of cushions or patches Section 6.4.2. The essential field equipment is can be added if required. listed in Appendix 6. Requires initial outlay on equipment Permanent quadrats unsuitable for short-term species May not be sensitive enough to detect change adequately for rarer species Species usually too scarce to use Domin or DAFOR scales; scale may need to be devised especially Can cause considerable disturbance pictorial record; can be used to pinpoint stands and accurately reposition permanent quadrats Good for monitoring of small areas of perennial species accurately areas quicker than other methods and allows extent to be extrapolated simple method of assessing abundance quantitative data Identification Provides permanent Photography Identification Marking of permanent quadrat locations Identification Quick and Expertise required Advantages Disadvantages Identification Produces Identification Covers larger Distortions can be caused if fixed-point photographs of quadrats are not aligned properly Size of quadrat affects measures of cover and frequency Subjectivity will introduce errors based on surveyors’ interpretations Low photographs are of sufficient quality Good for permanent quadrats Reasonable Low subjective cover scale is used Good if species readily distinguishable Reasonable Good if Better for temporary quadrats; permanent ones take time to relocate Good for single line transects; band transects take longer Reasonable Low if confined to small area Estimate of extent and/or number of clumps Presence–absence Estimate of cover, frequency and number of units Estimate of number of units or cover Index of population extent Semi-quantitative index Population size dataPresence–absence Good if species Efficiency Precision Bias Temporary quadrats for short-term species and annuals Long-term and perennial species and broader scale habitat quality Permanent quadrats for long-lived and perennial species Frequent and reasonably sized species Conspicuous species with large, well-defined habitats Recommended species group Large, conspicuous species forming discrete patches Methods for surveying and monitoring bryophytes Photography Quadrats Transects Visual estimates Total counts Table 13.1.

290 13.2 General methods 291

and representative data to be gathered for species Data analysis and interpretation that are spread over a large area or those that are Refer to Part II, Section 6.4.2 for details of how not conspicuous. to analyse visual estimate data. Data obtained by If the performance of individual stands of a tar- using subjective scales similar to the DAFOR scale get species is to be assessed over a period of time are imprecise and can only indicate broad- (i.e. for rare species restricted to a very few sites), scale changes in abundance. More quantitative permanent quadrats can be used. scales such as the Domin and Braun–Blanquet The scale of the bryophyte species being moni- scales are more sensitive to change. The appropri- tored and the problems of identification need to be ate scale for bryophyte monitoring will need to be established at the outset of monitoring. For many sensitive enough to detect the level of acceptable species of conservation importance, including change of the abundance of the target species. most UK BAP Priority Species, quadrat sizes need to be small (50 cm Â 50 cm maximum size). The 13.2.3 Transects method is best suited to those that form cushions and well-defined turfs or mats. Principles The procedure for randomly selecting quadrats Monitoring bryophytes with transects is an appropri- and a discussion of the pros and cons of temporary ate method when the target species is known to be and permanent quadrats is given in Part I, Sections frequent within a defined area and forms cushions 2.3.4 and 2.3.3, respectively. or turfs of a reasonable size so that a sample will give a reasonable reflection of the population as a whole. Field methods Location of random quadrats is covered in Part I, Field methods Section 2.3.4. Marking locations of permanent quad- Field methods for transects will generally follow rats is of great importance if the quadrats are to those for vascular plants (Sections 10.5 and 10.7 be accurately relocated. Quadrats can be marked and Part II, Section 6.4.6). Refer to Appendix 6 for with transponders as for permanent lichen quadrats the necessary field equipment. The simplest tran- (Section 12.2.2), and many of the same considerations sect form of counting species along a line (Section apply. Quadrats themselves should not be left per- 10.7.4) can be used, but even with species that are manently in situ, and care must be taken not to frequent within the habitat this method may not be damage the species or habitat. The problem of sufficiently sensitive to monitor populations accur- damage to the habitat caused by large numbers of ately, and single strip transects (Section 10.7.3), quadrats should be taken into account when deciding whereby all stands within a set distance from the how many quadrats to use. A summary of the recom- transect line are counted, can be used instead. It mended field equipment is given in Appendix 6. may be necessary to adjust the transect line to accommodate non-linearity of bryophyte habitat. Data analysis and interpretation Provided that sampling is representative, data can Data analysis and interpretation be analysed statistically by using standard tests See Sections 10.5 and 10.7 and Part II, Section 6.4.6, (Part I, Section 2.6.4). See also Section 10.5 and for details of how to analyse transect data. Part II, Section 6.4, for details of how to analyse quadrat data. 13.2.4 Quadrats 13.2.5 Photography Principles Making counts (Section 13.2.1) and visual cover Principles estimates (Section 13.2.2) may require randomly Photographs of broad-scale bryophyte habitat can selected temporary quadrats to allow comparable serve as a useful alternative to sketch maps for 292 13 BRYOPHYTES recording areas where target species occur and 13.3 BRYOPHYTE CONSERVATION can be used to examine successional trends, EVALUATION CRITERIA which could be used as an indicator of the development of unsuitable conditions. In practice, the 13.3.1 Key evaluation considerations presence–absence of the target species in stands The UK contains about a thousand bryophyte spe- on marked photographs is likely to be the most cies. About sixty-five percent of the known popular form of monitoring, as it is relatively European bryophyte flora occurs in the UK, which quick and cheap, but it is not suitable on a smaller has a unique blend of northern Atlantic, scale. Mediterranean and Lusitanian elements (JNCC, Fixed-point photography can be used for long- 2004). The extremely rich bryophyte flora of lived species. The technique is similar to that used Britain is widely recognised as a biological attribute for lichens (Section 12.2.3) and vascular plants of major international importance (Church et al., (Section 15.2.5). 2001). Knowledge of the taxonomy and distribution of bryophytes has always lagged behind that of vas- Field methods cular plants, for the simple reason that they are so For broader-scale habitat photographs, individual much smaller and less conspicuous (Hill et al., 1991). stands can be marked with easily visible markers The British Bryological Society (BBS) (www. and the area in which the species occurs can be britishbryologicalsociety.org.uk) has co-ordinated marked on the photograph after developing. The the collection of data on the distribution of species photographs should be clearly aligned to illustrate in both Britain and Ireland since its foundation (as the site and to include easily recognisable features the Moss Exchange Club) in 1896. The BBS Mapping to aid relocation on subsequent visits. Scheme was set up in 1960 to map the 10 km square For fixed-point photographs the scale must be distribution of the bryophyte flora of the British sufficient to allow recognition of the species from Isles. The data collected were used to create a data- the photograph, and so this technique is only feas- base on the geographical distribution of British ible for those species that form readily identifiable bryophytes and to produce maps of the British bryo- cushions, turfs or mats. Refer to Section 12.2.3 for phytes at the 10 km square scale, distinguishing details on fixed-point photography methods and recent from older records (Hill et al., 1991). In 1991 Appendix 6 for a summary of the field equipment the first (covering liverworts) of the three volumes required. of the Atlas of the Bryophytes of Britain and Ireland by Hill et al.(1991 et seq.) was published, with the two subsequent volumes published in 1992 and 1994. It Data analysis and interpretation is clear from the maps that there are several areas in Diagrams showing the position and size of the Great Britain that are seriously under-recorded and cushions, mats or turfs can be traced from the that there remains a great deal of scope for field- quadrat photographs and used as overlays. Areas work in Ireland. The BBS plans to continue to record can be calculated by using a grid overlay. Provided bryophytes at a 10 km square scale, in order to build that appropriate sampling has been used, the on the foundation laid by the Atlas. Experience with change in area between years can be analysed stat- other taxonomic groups shows that the publication istically by using standard tests (Part I, Section of an Atlas for any taxonomic group is the most 2.6.4, and Appendix 2). effective way of identifying recording errors and If slide film has been used, A3 prints can be drawing attention to under-recorded areas (Hill made with colour copiers. Quality can vary; only et al., 1991). The BBS have a network of Regional the higher-quality photocopiers give results with Recorders who co-ordinate bryophyte recording in sufficient detail at A3 from a 35 mm slide. More individual vice-counties. New or updated records versatility is available with digital format. from vice-counties are published each year in the 13.3 Bryophyte conservation evaluation criteria 293

Bulletin of the British Bryological Society.Periodically, suitable habitat for bryophytes. If they have these are compiled in a vice-comital Census already been to the site they may have a species Catalogue (e.g. Blockeel & Long, 1998). list or records for rare or scarce species that occur Bryophytes are a characteristic component of cul- there. If notable species have been found then tivated land in Britain, but knowledge of their status, records should be sent to the local county recorder distribution and ecology lags well behind that of along with specimen samples of these species. arable vascular plants (Porley, 2000). Bryophytes are included in several current conservation 13.3.2 Protection status in the UK and EU programmes. Under the Scottish Cryptogamic Conservation Project, known sites of selected threat- Four British bryophytes are listed in Annex I of the ened species have been surveyed and conservation Bern Convention: Marsupella profunda (Western recommendations drawn up. English Nature’s Rustwort), Petalophyllum ralfsii (Petalwort), Buxbaumia Species Recovery Programme, a programme of action viridis (Green Shield-moss) and Hamatocaulis vernicosus for bringing threatened species back from the brink (Slender Green Feather-moss). There are no bryo- of extinction, includes several bryophyte species phytes listed under the protection for species them- (Church et al., 2001). CCW continue to survey and selves in the Habitats Directive, but the above four monitor key sites for rare bryophytes, with attention species require Special Areas of Conservation (SACs) focusing primarily on BAP species. However, most to be designated for their protection (Annex IIb). targeted action for species conservation now takes Sphagnum, as a generic inclusion, and Leucobryum place under the UK Biodiversity Action Plan. glaucum are afforded protection by inclusion in The key considerations with regards to evaluat- Annex Vb of the Habitats Directive to avoid excessive ing species at a site are listed below. damage by commercial moss collectors. Thirty-seven species of British bryophyte (nine 1. Check lists of species of conservation importance liverworts and twenty-eight mosses) are listed in and protection status (see below for information Schedule 8 of the Wildlife & Countryside Act on which lists to check and where to obtain the 1981. The species listed under Schedule 8 can be relevant information). found on the JNCC web page www.jncc.gov.uk/ 2. Carry out a preliminary (scoping) survey to iden- species/plants/p5.htm. Forty-six bryophyte species tify whether there is a need for a detailed survey. (eleven liverworts and thirty-five mosses) are listed This kind of assessment should involve looking in Section 74 of the Countryside & Rights of Way for BAP and nationally notable (NS, S8, RDB, NT, Act 2000 as species of principal importance. The etc.) species on the list and then assessing the list can be found at www.defra.gov.uk/wildlife- assemblages of woodland taxa if in lowland countryside/cl/habitats/habitats-list.pdf. Britain or the Atlantic Assemblage (oceanic spe- Sixty-four species (thirteen liverworts and fifty- cies that occur along the Atlantic seaboard – one mosses) are currently priority BAP species. The Atlantic fringe of Europe where there is higher species and their Biodiversity Action Plans can be rainfall and atmospheric humidity) if in the west found on the UK BAP web page www.ukbap.org.uk/ (see Hodgetts, 1992). What part of the country the lichens.htm. Bryophytes have also been taken into site is in should be taken into account, as there is a account in several of the Habitat Action Plans, for gradient of decreasing diversity roughly from the example in the Action Plan for upland oakwoods north-west to the south-east. If a reason has been (Church et al., 2001). identified for carrying out a detailed survey then one should be carried out by an expert bryologist. 13.3.3 Conservation status in the UK 3. A local county bryological recorder could be contacted. The list for these can be found on the British The Red Data Book for bryophytes has been com- Bryological Society web page (see above). They may pleted for Britain but there is no equivalent for have information on whether the site contains Ireland as yet. The development of a Red Data List 294 13 BRYOPHYTES

for bryophytes in Ireland has been recognised as a not form particularly good examples of woodland Medium Priority additional work under Target 2 of community types, and as a consequence a few the Plant Diversity Challenge (JNCC, 2004). Eighteen woods of great importance for bryophytes had bryophyte species (one liverwort and seventeen escaped notice before 1992 (Hodgetts, 1992). mosses) are classified as extinct, twenty-four as crit- However since 1992 when the SSSI guidelines for ically endangered (two liverworts and twenty-two non-vascular plants were published, it has been mosses), forty-two as endangered (four liverworts, possible to designate SSSIs purely for their bryo- one hornwort and thirty-seven mosses), sixty-six as phyte interest. Several SSSIs now exist where the vulnerable (twenty-five liverworts and forty-one primary interest is the bryophyte flora (Church mosses), seventy-six as near threatened (twenty- et al., 2001). four liverworts and fifty-two mosses) and twenty- SSSI criteria for designating a site for bryophyte four as data deficient (six liverworts and eighteen interest are described by Hodgetts (1992), which mosses) in the GB Red Data list. Of the species that can be found at the JNCC web page www.jncc. are without IUCN classification, a group of fourteen gov.uk/publications/sssi/sssi_content.htm. In brief, species are classed as nationally rare (four liverworts the main requirements for site selection are the and ten mosses) and two hundred and fifty-four presence of the largest population of a Schedule 8 as nationally scarce (eighty liverworts, two horn- or Red Data Book species within an Area of Search worts and one hundred and seventy-two mosses). or the presence of an assemblage of notable species In time, these species will also be assessed against that scores above a certain threshold . The latter IUCN criteria. A full list can be found on the uses a scoring system that includes rare and scarce JNCC web page www.jncc.gov.uk/species/Plants/ species, Atlantic, sub-Atlantic and western British threatened/default.htm. However, as this list relies bryophytes, ‘woodland indicator’ bryophytes (for entirely on records from the BBS Atlas,somespecies use in eastern, south-eastern and midland lowland that it includes are merely under-recorded. woods), endemic species, non-endemic species The World Red List of Bryophytes currently threatened in Europe, declining species, and spe- includes 92 species. This list is only a small subset cies at the edge of their range (Hodgetts, 1992). of globally threatened species. The list can be found A refined version, assessing individual elements on the IUCN Species Survival Commission separately, may be developed in time. For full Bryophyte Specialist Group web page via the BBS details see the Guidelines. web page mentioned above. The Common Standards Monitoring (CSM) Guidance has now been produced by JNCC. It provides guidance on the identification of inter- 13.3.4 Site designation criteria est features, attributes, targets and methods of assessment for species on designated sites. Many sites that are important for bryophytes will The Guidance for Lower Plants is still under have been selected on the basis of habitat or vege- development. Information on the Guidance can tation types: bogs are a prime example. Similarly, be found on the JNCC web page www.jncc. bryophyte-rich Atlantic woodlands sometimes do gov.uk/csm/guidance. 14 * Aquatic macrophytes and algae

Aquatic macrophytes and algae can be divided into * Access to the plant being monitored: plants in two relatively distinct groupings: (a) the micro- deep water will require boats and possibly divers algae, such as diatoms and most green and blue- (either snorkel divers or those with subaqua green algae, which can only be seen, identified equipment). and counted with the aid of a microscope; and * Visibility: turbid conditions will hinder visibility (b) those vascular plants and macroalgae that can and make observations difficult. A bathyscope be seen and assessed by the naked eye. Macroalgae (glass-bottomed bucket) can be used, but problems include, in marine systems, the seaweeds and cer- may still occur. tain filamentous algae, and in freshwater systems * Substrate: if the sediment is soft, wading may be the stoneworts (e.g. Chara and Nitella species) and impracticable even in shallow waters; risks must filamentous algae (often lumped under headings be fully assessed. Sediment can also be disturbed such as ‘blanket weed’). by divers or by quadrats, leading to impaired The methodology for surveying and sampling visibility. microalgae in their various forms, e.g. single-celled * Annual and seasonal fluctuations: the extent of phytoplankton, diatoms growing on substrates and fluctuations in growth in some aquatic plants is benthic mats, and in various habitats, e.g. fresh- considerable. This means that survey timing is of water, estuarine and marine systems, has been critical importance when you are examining long- developed over the years and such methods are term population changes. generally well described. This section provides an * Relocation of sample points: accurately fixing overview of some of the main aspects of the differ- your position on large water bodies can be diffi- ent techniques for surveying and monitoring aqua- cult. Various methods can be employed; these are tic microalgae; the reader needs to consult some of detailed in the following sections. the recommended sourcesat the end of the book for further details or seek advice from an appropri- Because of these difficulties, most methods for ate specialist. Different techniques are required for monitoring deeper-water species do not provide aquatic macrophytes; perhaps surprisingly, methods fully quantitative estimates. Using divers can are still being developed to ensure that reliable yield quantitative data but is time-consuming and surveying and sampling can be undertaken in a requires training and specialist equipment, although systematic and repeatable form. sub-aqua equipment is not always necessary. Such Monitoring macrophytes in the aquatic environ- methods are similar to those used for aquatic habitat ment presents some problems that have necessi- monitoring; see Part II,Section6.3 for more tated the development of techniques that are information. distinct from those used for monitoring terrestrial There are also particular safety aspects to con- plants. In shallow, clear waters, adaptations of ter- sider when working in or near water. In particular, restrial techniques can often be used, but in deeper personnel should be trained in the relevant aspects or turbid waters the following problems must be of aquatic safety and the use of appropriate safety addressed. equipment. Surveyors should work in pairs and

# RPS Group plc and Scottish Natural Heritage 2005. 296 14 AQUATIC MACROPHYTES AND ALGAE

carry mobile phones or radios if working in remote and density. These can be estimated by using adap- areas. These should be used to contact colleagues at tations of methods for terrestrial vegetation such agreed times to confirm that sampling is proceed- as quadrats and transects. Each of these approaches ing safely and according to schedule. Boots or will require different methods, which need to be waders are a necessity but chest waders should be considered when any work is being planned. avoided, as they can seriously hinder mobility if Estimates of planktonic algal density can be they fill with water. Sampling should not be carried made in the laboratory from water samples col- out when a river is in spate or when weather con- lected in the field. These will require specialist ditions are particularly bad. Before attempting to techniques and identification skills, which will gain access to a water body, water depth and sub- not necessarily be covered by field staff. There strate stability should be checked (with a net pole are many different types of algae: filamentous, or similar) to make sure that it is safe to sample. unicellular or multicellular, epilithic or epiphytic. It Other safety aspects listed in Part I, Box 2.11, is beyond the scope of this Handbook to cover should be followed as appropriate. all these types i n d etail. Referreco mto- the mended sourcesat the end of Handbookthe or an appropriate specialist for further guidance if 14.1 ATTRIBUTES FOR ASSESSING required. CONDITION

14.1.1 Presence–absence 14.1.3 Community composition

Monitoring of aquatic macrophyte and particularly This may be an appropriate attribute to monitor for algal communities is often undertaken as part of aquatic macrophytes and microalgae; species lists water quality monitoring. These methods can be compiled from samples can be used to identify used for species monitoring; presence–absence in associations of species, which can be monitored vegetation samples can be used to map the distri- for changes in composition, or species richness bution of individual species, and semi-quantitative can be compared from different surveys. frequency data can be derived. Some aquatic plants are annuals, with considerable year-to-year fluctuations in range and number. 14.2 GENERAL METHODS Others can vary considerably in seasonal abundance Table 14.1 gives a summary of the general methods depending on conditions such as climate, nutrient suitable for monitoring aquatic macrophytes and load and competition from other plants (including algae. algal blooms). Presence–absence in areas of suitable habitat may be the most efficient way of monitoring these species. Monitoring areas of suitable habitat is 14.2.1 Quadrats and transects not covered in this part; refer to Part II (Sections 5.9, Principles 5.10 and 6.3.1)forfurtherdetails. In water bodies shallow enough to be waded, tech- Presence–absence of algae can also be used as a niques used for terrestrial vegetation such as quad- monitoring tool. For large benthic algae, samples rats and transects can be used (with suitable can be taken from marked areas. For smaller algae methodological adaptations). If the water is clear, and phytoplanktonic algae, more specialist extrac- visual methods can be used in deeper water for tion and analytical techniques are required. presence–absence surveys from a boat. It is also possible to carry out sampling in deeper water 14.1.2 Population size with snorkelling or diving equipment. Fully quantitative data can be collected (e.g. density and More detailed monitoring of macrophytes will cover), which cannot be obtained with grapnel sur- require estimates of population size such as cover veys (Part II, Section 6.3.2). Table 14.1. Methods for surveying and monitoring aquatic algae and macrophytes

Recommended Population Expertise species group size data Efficiency Precision Bias required Advantages Disadvantages

Grapnel Macrophytes Presence– Reasonable Fairly good Small rosette Boat handling Cheapest way Underestimates surveys a Charophytes absence for presence– and fine- Identification of semi-quanti- some species Large benthic Semi-quanti- absence leaved plants from tative sam- Only suitable on algae tative Moderate for are under- fragments pling of deep- still or slow-mov- frequency frequency recorded water ing waters communities Destructive Quadrats Macrophytes Presence– Good in Potentially Potentially Identification Provides full Expensive in and Charophytes absence shallow good, but good, but Boat handling quantitative deep waters transects Large benthic Frequency, water; expen- will depend will depend Diving (dee- data Turbid water algae cover and sive if diving on exact on exact per water/ makes recording density is required method method poor difficult visibility) Water/ Microalgae Presence– Low: Reasonable if Smaller spe- Boat handling Only way to Identification is substrate absence laboratory methods are cies will slip Identification sample algal expensive and sampling Density equipment sufficiently through net community time-consuming Community and time standardised Some species with any composition required hard to dis- degree of lodge from precision substrate

a see Part II, Section 6.3.2, for details. 297 298 14 AQUATIC MACROPHYTES AND ALGAE

The principles of quadrats and transects are cov- view of the vegetation, although if there are several ered in Sections 10.5 and 10.7, and further infor- layers of vegetation it can be difficult to part the mation on their applications for vegetation upper layers to see what is beneath. If samples are monitoring is given in Part II, Sections 6.4.2 and being recorded by using divers, this problem will 6.4.3 (quadrats) and 6.4.6 (transects). Guidance on be less acute, but difficulties may still occur in very the selection of appropriate quadrat size is given in cloudy water. Soft substrates can be stirred up by Appendix 4. the movement of divers’ fins, which will hinder accurate identification and recording, and quad- Field methods rats may sink below the sediment surface. Quadrat or transect locations can be either perman- Problems may also occur in eutrophic lakes later ent or temporary. For scarce species of conserv- in the summer if algal blooms occur. A stick with ation interest with a restricted distribution, a hook on the end can be useful for collecting permanent sample locations can be used. particular plants for closer examination. The However, for those species that are widely distrib- equipment required for field recording is sum- uted, or that fluctuate considerably in distribution marised in Appendix 6. (for example, those that occur in ephemeral habi- Surveys should be carried out during the period tats), temporary quadrats will be more suitable. from June to September, but the precise timing will Marking the locations of permanent sample depend on the species. Some species (e.g. those from points can be difficult; markers will need to be ephemeral pools in dune slacks) may require earlier more robust than those used for terrestrial loca- surveys. Repeat surveys should be at similar times of tions, particularly in fast-flowing waters. Coloured the year, unless seasonal variation is being investi- plastic stakes driven into the substrate can be used, gated, and repeated at least every three years for although if the substrate is soft and deep markers larger and typically more stable habitats, e.g. large can still be lost or buried. lakes, and annually for smaller habitats such as drain- The use of global positioning systems (GPS) to age ditches, channels and ponds in which change is relocate sample points can be considered if the sys- more rapid. Some rarer species may require monitor- tem is sufficiently accurate. Triangulation can ing more frequently. Initial surveys may have to be achieve a high level of precision. Alternatively, com- more frequent to establish how much variation pass bearings on two features on land at 908 from occurs, both seasonally and annually, and to deter- each other can be used. Good accuracy can also be mine the optimum monitoring time. achieved by lining up two features on land in one Some species cannot easily be identified under direction and two in another. This could involve water; it can be difficult to see important charac- lining up a feature on the shore with one on the teristics, and using a hand lens is not feasible. horizon, but the features must be permanent. Samples will therefore have to be taken of these Alternatively, stakes can be put on the shoreline. It species for identification either on the surface or is easier for a boat operator to steer a transect by later in the laboratory. keeping two markers in line than to hold to a com- Suitable safety clothing should be worn. pass bearing. Divers can swim out to where the lines Workers should also be aware of the risk of catch- cross and will know when to dive down to search ing Weil’s disease; toxic blue-green algae are also a for submerged permanent markers. An even more hazard at certain times of year. accurate method for work near the shore is to put Certain established survey and assessment posts in at regular intervals and measure the distance methodologies have included aquatic macro- from the nearest two posts to the sample point. phytes as part of the data collected. These include Data recording can be inhibited by turbid water River Corridor Surveys (National Rivers Authority) or by reflected sunlight. Polaroid sunglasses and/or and River Habitat Assessment (Environment a glass-bottomed box can be used to gain a clearer Agency). 14.2 General methods 299

Data analysis and interpretation and the time taken per sample. The volume should Analysis will depend on the information gathered be standardised for all samples. Phytoplankton (e.g. cover, density and frequency). See Part II, communities change with depth; you should Sections 6.4.2, 6.4.3 and 6.4.6 for details on the therefore either sample at a constant depth or analysis of vegetation data from quadrats and sweep the net through the entire water column. transects. Sampling at a set depth requires nets that can be opened and closed remotely. The net can be fixed toapoleortowedbehindaboat. 14.2.2 Water and substrate sampling Samples should be taken from strategic locations, e.g. along a transect for larger water bodies, Principles or at regular distances along a river. For larger Monitoring of microalgal species may be underwater bodies a GPS may be required to locate sam- taken for a variety of reasons: to assess overall ple points accurately (see Section 14.2.1 or the site importance of phytoplankton or benthic algae, to can be marked by a buoy. indicate the trophic status of a water body, to Algal cells will decay rapidly after collection and assess the population of a rare species, or to record should be placed in a suitable preservative as soon a toxic species (e.g. blue-green algae), a species as possible. Lugol’s iodine solution is the common- particularly used as a food plant by a larger organ- est preservative used (see Bullock (1996) for further ism of conservation interest, or an indicator spe- details). Samples should be kept in lightproof cies known to be associated with a rich community containers. or healthy conditions. Many methods exist for tak- Densities of species can be determined by ing and analysing freshwater algae. Some methods counting subsamples of each sample with a micro- involve specialised electronic equipment for in situ scope (some microscopes are specifically designed counting, but if you are interested in particular to facilitate counting algal cells, e.g. inverted species, samples must be taken to the laboratory microscope). The identification of phytoplankton for analysis. This section covers only the basics of is time-consuming and will probably require expert algal sampling. For more technical details and assistance. Several pieces of equipment are avail- methods consult Bailey-Watts & Kirika (1981)and able to facilitate counting. The most commonly HMSO (1984). available is a counting chamber modelled on the haemocytometer (developed to count red blood Field methods cells). This holds a precise volume of water in Phytoplankton which you can count the numbers of each species. The aim of surveying a water body for phytoplank- Several subsamples should be counted from each ton could be to determine presence–absence of sample. species but is more usually to achieve a measure Phytoplankton populations can fluctuate dra- of the number of cells and/or filaments of species matically within a few weeks and the timing of per unit volume of water. A water body can be peaks will vary from year to year depending on sampled with a sample bottle or other container weather conditions. Samples will therefore need to (particularly suitable for eutrophic water bodies) be taken at regular intervals throughout the year. or with a plankton net (a fine-mesh net with a bottle at the end). Both can be used for taking Benthic or epiphytic algae standardised samples of known volumes of Microalgae can grow on a wide range of substrates, water.Theareaofthenetframecanbesimply e.g. stones, leaves, sediment and concrete, in most calculated. The volume of water sampled can if not all aquatic and semi-aquatic habitats. The becalculatedfromtheareaofthenetframe,the range of techniques for assessing the presence– speed of water flow, the speed of dragging the net absence and abundance of algal species is, not 300 14 AQUATIC MACROPHYTES AND ALGAE

surprisingly, equally varied. The methods can be from other years, e.g. density measures, by using broadly divided into the following approaches. standard tests (Part I, Section 2.6.4).

* Direct observation of the colonised surface, e.g. viewing a leaf surface under a microscope and 14.3 REQUIREMENTS FOR SPECIES OF identifying and counting cells per unit area PARTICULAR CONSERVATION * Removing the algal cells from an area of the sub- IMPORTANCE strate, for quantitative estimates, from a known 14.3.1 Introduction area of leaf, rock or other surface. This can be achieved by removing, e.g. scraping the cells off Aquatic macrophytes and microalgae present a in situ, or removing the cells in the laboratory, e.g. diversity of form and taxa that will dictate the by washing or scraping. The cells are then sus- survey techniques necessary to assess status. pended in a known volume of water and can be Those species of aquatic vascular plant that grow counted using similar techniques as described for only as emergent species can in large measure be phytoplankton treated as terrestrial plants. The majority of species * Provision of artificial substrate in the water body pose particular problems and can be usefully for cells to colonise. These can be of such material divided into the following categories, some species as stones (cleaned of any algae), plastic plates or falling into more than one category. glass. The artificial surfaces are typically returned * Species with different growth forms, for example to the laboratory and sampled as described in the exhibiting floating leaves in some conditions but section immediately above in others only submerged leaves (e.g. Floating- * Sampling of soft sediment, e.g. by using a quadrat leaved Plantain Luronium natans). Some species and taking a sample with a large syringe or other can have emergent, floating and/or submerged suction device leaves, e.g. Arrowhead Sagittaria species. For large mats of algae, cover estimates can be * Species present as submerged plants only, which made by using quadrats (Section 14.2.1). can either only be seen from a boat or by a snorkel Laboratory analysis is carried out in the same or subaqua diver, or in turbid conditions only seen way as for phytoplankton samples. Counting of by divers or by using a remote sampling method, algae from sediment samples is problematic; e.g. grapnel or grab. small species will be obscured by sediment parti- * Species present only in a dormant form, which cles. Such techniques are described in texts such as can be short-term, i.e. a winter bud, or long-term, Flower (1985) and Bullock (1996). e.g. certain types of turion. It is important to remember that a number of species of aquatic plant of conservation significance can be depend- Data analysis and interpretation ent upon such propagules and that their apparent Presence–absence data from samples can be used absence from a water body can be transitory, e.g. to generate species lists for water bodies, which the stoneworts (Chara and Nitella species) and can be compared with those of other water pondweeds (Potamogeton species). bodies in order to determine, for example, level of * Some scarce species of microalga can occur at low eutrophication or salinity. Such a process can be density, e.g. mesotrophic and oligotrophic species developed by using quantitative data; sample data in regions where most of the water bodies have can be analysed with multivariate statistical pro- become eutrophic. Sampling strategies must grams such as DECORANA (see Section 20.2.1)to reflect this situation. examine differences in algal community structure between water bodies or at different times of An example is provided to give an insight into a year. Data can be compared with data collected particular species, Slender Naiad Najas flexilis. 14.4 Conservation evaluation criteria 301

be a belt transect 1 m wide with counts of shoots 14.3.2 Slender Naiad Najas flexilis every square metre or every other square metre. The Slender Naiad is a protected species under Schedule 8 of the 1981 Wildlife & Countryside Act and Annexes IIb and IVb of the EU Habitats and 14.4 AQUATIC MACROPHYTE Species Directive, and is listed on Appendix I of CONSERVATION EVALUATION the Bern Convention. It is also the subject of a UK CRITERIA Species Action Plan. 14.4.1 Key evaluation considerations Slender Naiad is a submerged macrophyte, occurring only in a submerged form. It is rare Owing to their special nature, aquatic macrophytes throughout its European range and is found in and microalgae have often been considered sepa- clear lowland lakes with low (oligotrophic) or med- rately in terms of their evaluation and site evalua- ium (mesotrophic) plant nutrient concentrations. tions from other elements of the flora. Aquatic Underlying shell sand or limestone outcrops are macrophytes in fresh waters pose particular prob- often present, making the water lime-rich. lems in terms of even determining presence and A monitoring protocol for the Slender Naiad absence; separate programmes of survey, evalua- recommended that the plant should initially be tion and monitoring are typically undertaken, monitored on an annual basis for 3 years to estab- especially with regard to the truly aquatic compon- lish a baseline, and then surveys should be ent, submerged species in particular, of lakes, repeated at 3 year intervals. reservoirs, rivers and canals. Surveying for this species has been undertaken However, the same range of legislation and des- by using various techniques including grapnelling, ignation as all other vascular plant taxa governs snorkelling and diving, although monitoring vascular aquatic macrophyte species. They are requirements vary depending on the abundance included in reviews of scarce and rare species, and distribution of the species. e.g. those by Stewart et al. (1994) and Wigginton Slender Naiad grows in beds at a depth of usually (1999), and are a recognised component of between 1.0 and 2.2 m. Diving surveys are there- site designation such as SSSIs (e.g. pondweed fore required to monitor this species. The first Potamogeton species). requirement is to map the location of the beds Although there are no alien freshwater macro- accurately. This may require the use of a GPS. phytes to which legislation might apply, there is an Once the beds have been located and mapped, they increasing imperative to include alien invasive or should be marked and subdivided with perman- potentially invasive aquatic species within the sur- ent markers so that transects or quadrats can be vey, evaluation and monitoring of aquatic habitats. relocated with accuracy. In the case of freshwater macroalgae, on the one The optimal monitoring time for the species is hand, the stoneworts (e.g. Chara and Nitella species) late July to early August when the plants are are dealt with similarly to vascular plants; for approximately 15 cm in height and have shining example, rare species are recognised under the white nodes, which makes them stand out from Wildlife & Countryside Act and are considered in other species. designation of sites such as SSSIs. They have their The species grows on fine silty mud and this can own Red Data Book (Stewart & Church, 1992). be a problem when placing quadrats as the mud Filamentous algae, however, e.g. species of becomes disturbed. Permanent transects, marked Cladophora, Vaucheria and Spirogyra, are generally with coloured plastic shafts driven into the sub- regarded as nuisance species; no rare or scarce spe- strate and weighted lines, are recommended in cies has been identified and dealt with in the same areas where the mud is deep, and can be used for way as aquatic vascular plants and stoneworts. all Slender Naiad sites. The recording method should They are considered with the microalgae. 302 14 AQUATIC MACROPHYTES AND ALGAE

Microalgae (including the macrofilamentous Relative to non-aquatic vascular plants, knowl- algae) have not attracted the same attention as edge on the distribution and health of popula- the vascular plants and stoneworts and there is no tions of aquatic vascular plants and stoneworts requirement that either the species themselves or is relatively poor owing to such problems as their indicator value in terms of assessing status of the inaccessibility of habitats, the underwater a freshwater habitat be taken into consideration. growth particularly of submerged species and Unusually, an algologist has provided data for a the relative difficulty in identification, e.g. the given site that identifies its value for particular stonewort species and pondweeds (Potamogeton species and which, alongside other characteristics, species). Both these groups contain a number of have led to designation or site safeguard, e.g. unu- scarce and rare species and both groups are valu- sual or rare desmid species in a series of ponds or able indicators of the conservation of wetlands an algal species indicating mesotrophic conditions. and waterbodies.

14.4.2 Protection status in the UK and EU 14.4.4 Site designation criteria

The chapter dealing with vascular plants in general Aquatic macrophytes are an important component (Chapter 15) applies to aquatic vascular plants and in the designation of sites of nature conservation in large measure to the stoneworts. value. They are taken into consideration in the Although able to invade a range of habitats, same way as other vascular plants and stoneworts. Japanese Knotweed Fallopia japonica and Giant There are no special SSSI criteria for designating a Hogweed Heracleum mantegazzianum are often con- site for these plants as there are, say, for bryo- sidered as ‘aquatic’ species owing to their favour- phytes (Hodgetts, 1992). ing the banks of rivers, streams, canals and lakes. Aquatic macrophytes are an important source of These alien invasive species are legislated under food, either directly or indirectly, for wildfowl; the the Wildlife & Countryside Act such that it is an extent and health of aquatic macrophyte popula- offence to spread them into the ‘wild’. The pre- tions are increasingly being taken into considera- sence of one or both species in a site is considered tion in those water bodies that do or that might to degrade its nature conservation value. support nationally or internationally significant populations of waterfowl species. 14.4.3 Conservation status in the UK As described above, the presence of Japanese Knotweed and Giant Hogweed, species erroneously The Red Data Books for vascular plants in the UK described as ‘aquatic’, along with other aquatic and Ireland apply to aquatic vascular plants. The alien invasive species, e.g. Australian Swamp- stoneworts of the British Isles have their own Red stonecrop Crassula aquatica, is a negative aspect of Data Book (Stewart & Church, 1992). the flora of freshwater bodies. 15 * Vascular plants

There are a series of general problems that can be other boundaries, distance to nearest neighbouring encountered when monitoring vascular plants, not populations, or by 1 km square, etc. Populations all of which will apply in every case. The type of that fluctuate from year to year may form discrete plant being surveyed, the methods used and the patches in some years when numbers are low, but recorders can all affect the results (Rich & merge when they are high. Again, it is best to state Woodruff, 1990). how populations are defined. A long-term view of the functioning of metapopulations may be very difficult to obtain. Defining an individual Defining an individual plant can be a problem; opinions differ between botanists. With annuals Method selection according to growth or biennials there are rarely difficulties as their patterns growth forms are generally simple. Perennials The monitoring methods must also allow for pat- have more varied growth forms. If the species terns of growth. For instance, Carnation Sedge grows in dense clumps, the clumps might be Carex panicea is a clonal species, which grows composed of one or more individuals, and species radially outwards from the initial plant; the centre spreading by stolons or rhizomes may form single of the patch then dies off. A permanent quadrat or mixed patches of clones. Clonal perennials centred on a young plant will thus show an initial may also fragment, resulting in two or more increase and then a longer-term decrease as the parts of the original plant. Trees tend to be plant grows outwards. Most species show clustered counted as individual trunks, although some microdistribution patterns. trees such as Aspen Populus tremula spread by suckers. Vegetative and flowering plants Alternatively, proxy measures of abundance can Most populations consist of both flowering and be used such as the number of ramets or shoots, or vegetative individuals. Consequently, counting percentage cover, rather than the number of only flowering individuals will underestimate individuals. total population size. Surveyors should therefore The method by which an individual is defined be able to identify species from vegetative growth, should be clearly stated at the outset of survey and it may be worthwhile distinguishing the pro- and monitoring, so that this can be followed portions of flowering and vegetative plants. There subsequently. are relatively few vegetative identification keys available (see Rose, 1981; Rich & Jermy, 1998). Defining populations Plants in flower may be easier to see than vege- The definition of the extent of a population varies tative ones; simple presence–absence can be between botanists. It is possible to delimit popula- rapidly assessed on this basis. The number of flow- tions by compartment, habitat, site, ownership or ering plants can be used as a proxy measure of the

# RPS Group plc and Scottish Natural Heritage 2005. 304 15 VASCULAR PLANTS

abundance of a colony for example, as used for adjusted to take into account yearly variations in monitoring Alpine Milk-vetch Astragalus alpinus. growing and/or flowering times caused by weather conditions (e.g. an early or late spring). If flowering Variation due to timing of survey times are delayed, this should be noted and the Individualsmayhaveaperiodofdormancybelow survey postponed. ground when they do not appear for a year or more. For instance, individual plants of Early Spider Observer bias Orchid Ophrys sphegodes may be dormant for one or The recorders themselves are a major source of two years (see Hutchings (1987a,b), but see also variation (Rich & Woodruff, 1990), (Bibby et al. Sanger & Waite (1998)). Some plants show seasonal (2000) give comparable assessments for bird sur- variation in appearance, and are only visible or veys); recorders are better at repeating their own identifiable at particular times of year. For instance, work than other people’s. Experienced botanists leaves of Lesser Celandine Ranunculus ficaria appear almost always provide better information than in the winter and plants flower in the spring; there inexperienced surveyors, whereas experts may be are no visible signs of the plants from about July to needed for particularly critical species (e.g. November. Other species such as Small Cow-wheat Taraxacum clovense). However, even experts make Melampyrum sylvaticum or Mountain Scurvy-grass mistakes. Factors such as weather, season, the Cochlearia micacea are only readily identifiable when level of fatigue of the recorders, and even biting flowering and/or fruiting. The timing of surveys insects in some locations, result in subjective vari- should therefore be specified and standardised. ation from day to day. Population sizes may vary depending on when Large, broad-leaved or clumped taxa are better the surveys are carried out for other reasons. recorded than small, well-dispersed or fine-leaved Populations of annuals may increase through the taxa. Species at ground level in tall or dense vegeta- summer owing to continued recruitment from tion (e.g. Adder’s Tongue Ophioglossum vulgatum) can seed. In this case, seedlings can be recorded separ- be easily overlooked. ately from established plants, but the problem Surveys of small, intensively searched areas are then becomes one of deciding when a seedling more repeatable than surveys of larger, less inten- becomes an established plant. For example, sively searched areas. Semi-quantitative surveys Kidney Vetch Anthyllis vulneraria seedlings are based on objective measurements (e.g. presence– often abundant in May, but few survive to flower- absence) are more repeatable than are quantitative ing; counts including seedlings will be much surveys based on more subjective measurements higher than counts of established plants only. (visual cover estimates in particular are often There are often large fluctuations from year to inconsistent). year due to climate, especially in annuals, and biennials (e.g. gentians, Gentianella spp.) may be abun- Accessibility dant in alternate years. It may be best to survey Some types of habitat, such as cliffs and wetlands, some species only in good years, or to survey in can be difficult to survey thoroughly. Health and greater detail in good years. safety considerations may require pairs of sur- Dates of surveys must be recorded to aid the veyors, with consequent increases in costs. determination of future survey dates, and to aid data interpretation if counts are unexpectedly Frequency of monitoring high or low (e.g. past the main flowering time for Guidance on establishing the required frequency counts of flowering shoots). Poor weather should of monitoring is given in Part I, Section 2.1.5. ideally be avoided, but if this is impossible, the However, of prime importance is the need to weather conditions should be recorded. If the ensure that changes are detected before they objective of monitoring is to gain accurate informa- become irreversible. The optimum frequency of tion on population sizes, the survey date should be monitoring therefore needs to be based on 15.1 Attributes for assessing condition 305

potential intrinsic rates of change and the likeli- flowering plants alone. Vegetative identification hood of extrinsic factors influencing a feature. skills may be required. Plants with the highest potential rates of change and those that may require the most frequent surveying and monitoring are: 15.1 ATTRIBUTES FOR ASSESSING CONDITION * annuals or short-lived perennials; * species with a small population (i.e. only a few 15.1.1 Presence–absence individuals or a few small colonies); For some plants, basic monitoring may simply * species with a very restricted, local distribution involve establishing whether or not they are still (rather than a widely scattered distribution); present at a site. This will also apply to baseline * species with low reproductive output; surveys of new sites, during which a species list * species in vulnerable or dynamic habitats; and can be drawn up to identify priority species for * species in habitats subject to sudden changes in monitoring. More detailed monitoring based on management. presence–absence in grid cells (e.g. 1 km Â 1kmor From the above, a priority list can be devised for the 50 m Â 50 m squares) can be used to map the range survey and monitoring programme. However, prio- of a species. Repeat surveys can then be used to rities may change with time; for example, if the assess whether the species’ range is expanding or status of a species shows some stability over a contracting. long period of time then the frequency of monitoring can be reduced. 15.1.2 Population size

Key points for survey Determining the size of a species’ population is key to assessing its status. However, as discussed above, * If the species is easily detected, populations can there may be difficulties in distinguishing indivi- be counted directly or estimated from samples; if dual plants to ascertain the actual population size. the population is localised or relatively small, Counts of shoots, number of flowers, number of then whole-population methods can be employed; flowering stems, cover or percentage frequency, otherwise, samples should be taken. Demographic etc., can be used as proxy measures of population techniques are required to detect changes in popu- size. lation structure (Section 15.2.4). Photography Further discussion of measures of plant species (Section 15.2.5) can provide general information abundance is provided in Part I, Section 2.1.2. about the habitat as well as about the plants themselves. * If some colonies of a specific species are inaccessi- 15.1.3 Plant growth and reproduction ble (such as cliff-face species), only a sample of the total population may be available for survey; the The relative size of plants or parts of plants (e.g. proportion surveyed will be an unknown percen- height, clump diameter) can give an indication of tage of the total population. how well the plants are growing in a certain habitat. * For statutorily protected species, such as those The basic assumption is that the larger the plants, listed on Schedule 8 of the 1981 Wildlife & the better they are growing. Additionally, if plant Countryside Act, total counts should be conducted size is measured between two points in time and at least every 5 years as part of their quinquennial growth rate is calculated, a high growth rate relative review. to that plant’s growth capability will indicate good * Populations often contain a significant propor- conditions. Surveys of plant size can also give infor- tion of non-flowering individuals. Population mation on population structure and life history for size therefore cannot be assessed from number of some species. Similarly, the number of flowers, 306 15 VASCULAR PLANTS

flowering heads, flowering stems, flowering plants number of leaves or fronds, and number of shoots. or fruits indicates the reproductive health of the The length of shoots produced in the current field population; the assumption again is that the more season can be measured, but the timing of this flowers, fruit, etc., the better the plants are growing. should be restricted until after the growing season. Both measures are sensitive to environmental fac- This can be difficult if there is a mild winter and the tors such as grazing and weather. plants keep growing. When assessing the numbers of flowering The frequency of survey should be tailored to the shoots it must be remembered that aerial shoots growth rate and longevity of the species. Annuals can be grazed, thus reducing apparent numbers, or biennials may require several surveys in the and that not all individuals will flower every year. same growing season whereas herbaceous peren- Also, as a result of the variability of growth and nials, shrubs and young trees may only require flowering between years and the short flowering measurement once a year. Similarly, older trees period of some species, assessments should be con- may only require surveying once every 4–5 years. ducted annually at the same time of season Analysis of trends in plant size are likely to be (although actual calendar dates may vary if a sea- more meaningful if there is an indication of why son is delayed or advanced compared with the plant size is being affected and what environmen- average). To obtain accurate results, if the attribute tal factors may be acting on the plants. Techniques is dependent on a period of a certain type of such as regression analysis may be appropriate to weather (such as wet weather for frond production examine the effect of environmental factors on the or sunny weather for flower emergence), the tim- health of a population. ing of the survey should be such that the survey is Plant size distribution within a population can only conducted after this critical weather has give some information about population structure. occurred. For example, surveys of shoots of The simplest measures used to characterise the Oblong Woodsia Woodsia ilvensis are only conducted distributions are: after a period of wet weather and between two * mean plant size; specific calendar dates (Geddes, 1996). * variability in plant size; and Any monitoring of plant size is likely to be long- * skew, i.e. whether the size distribution has long term and will probably involve tracking the pro- tails to one side or another, implying that there gress of individual plants. Such methods are prob- are some individuals that can be very different in ably best used to gain broad indications of the size from the majority. health of the population and are useful in that they are relatively rapid to conduct. Results should Analysis of these parameters may be used for then be used as a trigger for more intensive studies limited predictive purposes. If the distribution is should plants appear to have a reduced growth rate seen to be changing so that the numbers of small compared with what is expected or has previously plants (new recruits) are decreasing, it may imply been observed. that the population has low numbers of young The size of clonal plants can be estimated by the plants and could be on the verge of a population total area covered by the plant or the sum of the crash. dense patches of shoots within a total area. For detailed accounts of the methods for survey- Measures of plant size over an extended period, ing and monitoring the size and flowering of coupled with observations such as the size at which plants, see Section 15.2.4. sexual maturity is reached or the plant ceases to flower, can give useful information on the life his- 15.1.4 Population dynamics and structure tory of a species and are a step towards detailed demographic studies. The long-term status of a species is generally The variables that can be measured include dependent on many more factors than distribution height, diameter of clump, rosette or trunk, and population size. A population’s viability will 15.2 General methods 307

also depend on its structure and dynamics, includ- within an acceptable timescale. Site maps showing ing longevity, recruitment, mortality and other locations of plant populations can be annotated aspects of life history. Such attributes may, there- with additional information such as the presence fore, require monitoring (see Part I, Section 2.1.2). of nearby colonies or soil types. This information may help to identify the stages of a species’ life cycle at which it is more vulnerable, Field methods which will in turn aid the targeting of management In its simplest form, you walk through the site, actions and resources. Monitoring such attributes visiting the appropriate habitat(s), and estimating will be particularly important for rare species, each population size by eye or by counts if possible. which are confined to only a few sites or Population estimates can either be exact figures, populations. where sufficient time is available, or based on the Details of the population structure and logarithmic scale (1–10, 10–100, 100–1000 plants, dynamics of a species can be gained from two etc.) to give an order of magnitude. Alternatively, a types of survey. crude indication of the population size can be given by using the DAFOR scale (Part II,Section6.4.2). 1. Surveys measuring performance indicators such These methods are somewhat subjective and esti- as cover, numbers of flowers, etc. and size of mates vary between observers. Estimates of popula- plants (e.g. where it is hard to identify an indivi- tion size may vary depending on the effort taken or dual plant). the time spent recording. If a variety of sites are to be 2. Surveys that use demographic techniques to gain surveyed and compared, a standard amount of time detailed information on the life cycle of a species per unit area or a standard route should be allocated and to identify vulnerable stages at which popula- for recording to make the data more comparable. tion numbers decrease compared with the pre- Methods based on timed searches or standard vious stage (Section 15.2.4). walks are recommended for assessing large areas of vegetation and where the use of systematic total 15.2 GENERAL METHODS counts (Section 15.2.2) or sample-based estimates is not possible or too time-consuming. Standard Table 15.1 outlines the general techniques for sur- walks follow a fixed pattern, such as a ‘W’, and veying and monitoring higher plants. start at the same place in each survey. To increase consistency further, it is also useful to fix the time 15.2.1 Look–see method spent searching along the route. Timed searches may also use haphazard searches of suitable habi- Principles tat or random rather than standard walks. Random This method is appropriate where it is only neces- walks are conducted by calculating a random com- sary to establish the presence of a species or to gain pass bearing, walking on that bearing for a certain a rough estimate of a population size. Population distance, then walking on another random bearing sizes can either be obtained by total counts or esti- for the same distance and so on. Every plant of the mated from crude samples obtained by timed target species within a defined band (e.g. 1 m) adja- counts or standard walks. cent to the standard or random walk is then The look–see method is widely used and probably counted, forming an incomplete total count. applicable to the widest variety of situations but is The value of these methods is considerably somewhat subjective and provides relatively crude enhanced if the areas searched and the locations data. It is often used as a preliminary method to of any populations detected are marked on a map. obtain a general impression of the status of a plant (e.g. Mountain Scurvy-grass (Dalby & Rich, 1994)). Data analysis and interpretation This method has the advantage that it is quick to At its simplest, the results of this method are used carry out; large areas can therefore be assessed to establish whether a species is present or its 308

Table 15.1. Methods for surveying and monitoring higher plants

Recommended Population Other Expertise species groups size data attributes Efficiency Precision Bias required Advantages Disadvantages Look–see All Presence–absence High, for Low Observer Identi- Rapid Accuracy Minimum intended bias, tends to fication dependent estimates purpose underestimate skills on time population spent size where surveying; estimates does not show made flux in population structure

Systematic All; limited Presence–absence High, labour- Very high If grids are used, Identi- Very precise Only total counts to small, Exact totals intensive they may follow fication and normally appropriate for localised of population a pattern in the skills accurate small, localised populations vegetation such populations as ridge and furrow

Frame All ground flora Presence–absence Height Relatively Cover values Conspicuous Identi- Cover values Cover quadrats and shrubs Cover Flowering time- can be very species often fication provide good estimates can for cover/ Density consuming, imprecise overestimated by skills and description of be imprecise density a especially if cover experience of the contribution Cover scales very accurate estimates cover value of a species to a such as Domin cover values estimation vegetation are non-linear required community and thus statistical analysis is limited Requires large number of quadrats Tall and coarse vegetation causes difficulties with small quadrats Very time- consuming and requires large number of samples to detect rarest species Not suitable for individual species in dense habitats Cover estimates can be imprecise Cover scales such as Domin are non-linear and thus statistical Data are quick to collect Method is easily repeatable by different surveyors Most objective, precise and accurate way of measuring cover Quicker to record than quadrats Cover values provide good description of the contribution of a species to a vegetation community Identi- fication skills Identi- fication skills and experience with method Identi- fication skills Identi- fication skills and experience of cover value estimation species with clumped distributions; shoot frequency is biased against smaller plants over-estimates cover of spreading species spreading species Conspicuous species often give overestimated cover estimates Biased against Cover values can be very imprecise Good Low Low High Low, but High HighRelatively time- Over-estimates consuming, especially if very accurate cover values required Height Flowering Vertical canopy structure Height Flowering Size Frequency Cover Cover Frequency Frequency Cover Density Ground flora Presence–absence Short ground flora Presence–absence All, but especially useful in tall or sparse vegetation All, but especially useful in tall or sparse vegetation b c d d for Frame quadrats y quenc fre Point uadrat q Line and point intercept nsect tra Belt nsect tra

309 310

Table 15.1. (cont.)

Recommended Population Other Expertise species groups size data attributes Efficiency Precision Bias required Advantages Disadvantages analysis is limited Permanent Trees and shrubs Frequency Population Low if data High, but Plots may not Identi- Very detailed Time- plots e Cover structure on perfor- cover values remain represen- fication skills data can be consuming Density and dynamics mance of can be tative of wider collected Plots may individuals imprecise habitat Observed change become lost are collected can be related to or unrep- performance of resentative individuals over long time periods Temporary Trees and shrubs Frequency Height Quicker to High, but Generally low Identi- Quicker than Data collected plots f Cover Size record than cover values fication skills permanent plots are less Density permanent can be Randomisation detailed than plots imprecise ensures sample for permanent remains plots representative Plotless Trees and shrubs Density Height, etc., High Varies with Serious bias Identi- Quick method, Biased if trees sam plingg if required type of occurs if species fication skills which requires are non- sampling distributions are little equipment randomly method not random distributed Does not select a random sample of trees Selected Species that form Presence–absence Can be used High High Colonies Identi- More efficient Extrapolation colonies discrete colonies to study may not be fication skills use of available to whole population representative time with large population structure of the entire populations difficult if few population colonies if not randomly monitored or selected Survey must run for a considerable length of time and frequent surveys needed non-randomly selected Difficult to analyse objectively or with any accuracy Yields detailed data with high degree of confidence Enables rapid assessment of the environment and provides permanent pictorial record Identi- fication skills and experience with mapping methods Identi- fication skills Photography skills Under- or over-estimation due to difficulty of interpretation applicable High None High Not Low, very labour- intensive and sexual recruitment General habitat information Life history data, vegetative Extent Cover Absolute counts Presence–absence Presence–absence ...... All All 6.4.6 6.4.2 6.5.4 6.4.3 6.5.2 6.4.5 6.5.3 See Section See Section See Section See Section See Section See Section See Section a b c d e f g Photography Demo- graphic techniques 311 312 15 VASCULAR PLANTS

population is above a threshold level (i.e. a change marking individual plants and the use of grids limit, which may be the minimum requirement for and transects to delineate search areas. monitoring). Thus, there is no doubt over a positive To ensure consistency between searches, it is result, but if the species is not found in sufficient important to ensure that a record is kept of the numbers care must be taken in interpreting such area searched (preferably on a map), the methods negative results. This is particularly important for used and the total search time. EIA studies. In particular, there are inherent problems with observer bias. Some surveyors will tend Maps and diagrams to overestimate population sizes by this method, The location of individual plants or colonies should whereas some will underestimate. Some surveyors be marked on a small-scale site map (1 : 5000 or will be consistent in population estimation and larger). If a map of the site with a superimposed some will not. The look–see approach tends to grid (see below) is used, the cells of the grid can be underestimate population size compared with marked as they are surveyed, to ensure that no cells more systematic approaches. remain unsurveyed. Using a grid also makes map- The inconsistencies of approach with this ping more accurate because the lines of the grid can method will make comparison of repeat surveys be numbered, giving each cell unique co-ordinates from different years difficult. If count time, count which can assist the relocation of plants on future area or both are standardised, comparisons are surveys. Maps, sketches and photographs can also more valid, but differences due to observer bias assist the relocation of plants on subsequent sur- and the relatively crude data that are obtained veys. Maps can be annotated with other information will mean that the reliable identification of such as the presence of nearby colonies, features to changes will be unlikely unless they are large. As aid relocation and general habitat information (e.g. annual counts are not based on samples, no mea- vegetation height and presence of other species). sure of variation is obtained and consequently differences between two years cannot be compared Plant or population location markers statistically. Similarly, trends over a number of Individual plants can be marked by using flags, years might be examined informally, but results canes, tags, hat pins, etc. to ensure that all are should be treated with caution. To maximise the counted. Marking plants also helps to avoid tram- sensitivity of the technique to detecting trends, pling, as well as delineating the extent of the col- assessments should be made as often as possible, ony and making the plants more visible in ideally on an annual basis. photographs (Section 15.2.5). Permanent markers can be valuable for relocating populations but 15.2.2 Systematic total counts should be discreetly positioned to avoid attracting interest from members of the public or livestock. Principles A map will probably be necessary showing the rela- Systematic total counting is a method that can be tion of the marker to the plants. used to ensure that all areas are covered and all plants counted. This method increases consistency Tape measures and therefore produces more accurate results, but For perennial species, a pair of tape measures with it is more time-consuming and costly than the fixed permanent starting points can be used to look–see method (Section 15.2.1). Systematic total record the ‘co-ordinates’ of plant locations. They counts can only realistically be carried out on small can also be used as transect lines or to set up grids populations. to aid systematic coverage.

Field methods Grids The aim is to count all individuals in the popula- A grid can be superimposed on a site. This can assist tion. Techniques to improve accuracy include a surveyor in locating positions within the site, 15.2 General methods 313

determining the location of a plant or simply if the full distance to the next point is walked. In checking that every part of the site has been sur- such situations, carry out the process in stages. If veyed. The numbers of plants in each cell can then the ground is very uneven, decrease the cell size to be counted. Sufficient details should be given to save time. ensure relocation of the grid in subsequent The grid, or key parts of it (e.g. corners), can be surveys. permanently marked (which considerably The grid is merely an aid for the surveyors and enhances the accuracy of relocation), but reloca- thus the size of the component cells can be tailored tion should also be possible by using grid bearings to the individual site and particularly to the size of in case these markers are lost. In addition, a loca- the plants under survey. The orientation of the grid tion map of the origin of the grid should be drawn should be such that it is easy to use; if the habitat is up (see Appendix 5 for further information on per- an obvious rectangular shape, then one of the manent markers). A small grid can be marked with boundaries of the habitat can be used as the edge string but larger ones are better marked at the of a row of cells. More usually, the habitat is an intersection points with canes or string around irregular shape and in these cases it is easier for the trees, etc. These markers should be highly visible; surveyor if the orientation of the grid is aligned to a attempting to distinguish a bamboo cane at 100 m straight feature such as a path or fence line. In the against a woodland with bracken understorey is absence of any helpful features the grid can be impossible. Attaching highly visible tape to the oriented on simple compass bearings (e.g. north– canes assists visibility. Cell corner markers should south). If other features are used, the bearing of only be removed once the cell and adjacent cells these features should be taken and used for defin- have been surveyed. ing the grid. Cell size is usually determined by the detectabil- It should not be forgotten that there is a differ- ity of the plant being searched for. There is little ence between magnetic and true north. Thus the point in having to subdivide the cell in order to compass will read the magnetic north, but bearings search it, so keep the cells small. Suggested sizes worked out from a map will be based on true north are 50 m Â 50 m when surveying an open woodland and will need to be converted to magnetic north or other open habitats, and 30 m Â 30 m in dense before use. (Useful acronyms to remember are: woods or other closed habitats. MUGA, Map Unto Ground Add (6 degrees); and Also note that there will usually be a large num- GUMS, Ground Unto Map Subtract (6 degrees).) ber of partial cells around the perimeter of the grid The cells of the grid should always be located by that have some of the habitat to be surveyed and using compass bearings to maintain accuracy. some of the adjacent habitat. It is useful to be Ordinary compasses have been found to be very familiar with the area of each cell so that you can inaccurate for this type of work; a sighting compass visually estimate or measure the area of habitat is essential. When setting out the grid it is helpful within these partial cells and adjust the counts to have two people, one to walk ahead to the next accordingly, especially if estimating density. grid intersection point (pulling out a tape measure Alternatively, only survey full grid cells, although while walking for the length of the cell). The other this will remove any edge effects from the results. remains at the last intersection point, ‘sights’ the The location and relocation of grid cells can be a first person (i.e. checks that they remain on the time-consuming process; it may be more feasible to correct bearing) and winds in the tape measure. sample a random selection of grid cells rather than This speeds the procedure up, especially if, once attempting to count in every cell. In this case the the second intersection has been identified, the survey is no longer a total count, but estimates of original sighter walks up to the person ahead and density, etc., from the sample of cells can be extra- keeps on walking to the third point, this time being polated across the entire site. sighted themselves. If the ground is uneven, the The equipment required for field surveying and person ahead may be lost from view by the sighter monitoring is summarised in Appendix 6. 314 15 VASCULAR PLANTS

rhizomes and grow outwards from the colony ori- Data analysis and interpretation gin (e.g. Carnation Sedge Carex panicea or Sand In theory, changes in abundance are simply mea- Sedge C. arenaria). If a permanent quadrat is used sured by calculating the difference in the total for such species, and a colony grows beyond the counts between one survey and the next. boundaries of the quadrat, counts of shoots within Increases or decreases can be expressed as percen- the quadrat will eventually decrease in number; tages of the initial population. In practice, how- such a decrease could be misinterpreted as a ever, some individuals will probably be missed, so decrease in the size of the colony. A survey of the populations will be underestimated. This underes- colony with the boundaries of the survey area timation is unimportant if an index of population defined as the boundaries of the colony would not size can be used for detecting change, provided encounter this problem. that the bias caused by failing to detect all indivi- Selecting discrete colonies provides an ideal duals remains constant from year to year. opportunity to investigate a species in detail, either However, it may be difficult to separate signifi- by using demographic studies or by collecting data cant trends from natural fluctuations in population on performance indicators, which can be used to size; 5–10 year means of counts can be used to calibrate data from other colonies. eliminate some of this variability. Regression ana- If a particularly good flowering year is noted lysis or other techniques can be used to statistically from flowering stem counts, it may be worth assess the significance of trends in population size. while conducting a census of the whole population Time-series analysis can also be used for long series at the site; new colonies may be found in this way. of data to separate cyclic fluctuations from under- In addition, this type of count repeated in ‘good lying trends in population size. years’ may serve on its own as a method of assessing trends in population size. 15.2.3 Selected colonies Wherever possible, colonies should be selected on a random or stratified random basis (see Part I, Principles Section 2.3.4) and statistical methods should be This method involves estimation of the population used to determine the number of colonies required size of one or more selected colonies of the target to yield results with adequate precision and accu- species. These colonies are used as sample indica- racy (see Section 2.3.5). tors of the health of a population as a whole. The If monitoring resources are limited, it may only method is applicable to species that have some be possible to monitor one ‘representative’ colony. colonies in areas where access is problematic; in In this case, no information will be obtained on the this case, you can monitor easily accessible colo- variability of the condition of colonies. The worst nies and make the assumption that the health of case scenario would be that the selected colony these colonies is indicative of the health of others. thrives while the others, which are not being mon- A decrease in colony size should trigger surveys of itored, decline. Caution should therefore be exer- other populations. This method is also appropriate cised when monitoring a larger population from for a population consisting of numerous scattered one or a small subset of colonies; other sites should small colonies. In such cases it may be very costly to at least be checked occasionally on a presence– attempt to survey the entire population compre- absence level. Any decisions on a change in manage- hensively to an adequate level of detail. ment as a result of a single-colony survey should be Because the survey area is not an arbitrarily made only after further surveying of other defined area such as a quadrat, but an existing colonies. colony, a better picture emerges of how each colony size is changing and/or whether each colony is Field methods moving but not increasing in size. This might be Colonies should ideally be randomly selected for the case with species that possess underground survey and monitoring. However, colonies that are 15.2 General methods 315

especially remote and thus costly to survey, or total counts (Section 15.2.2)orquadrats(PartII, located in inaccessible areas, may have to be Section 6.4.2). Refer to these sections for details removed from the pool of possible colonies to sur- of field methods. Selected colonies are good candi- vey. If less than 10% of the colonies are excluded on dates for conducting demographic studies to mea- these grounds, departures from strict random sam- sure the longevity and turnover of individuals pling are unlikely to be significant. However, (Section 15.2.4). if more colonies are excluded, the results will not It is also recommended that a wide range of colo- be representative of the entire site. Nevertheless, nies (or even the entire population) be surveyed the results will provide an indication of the status briefly on a regular basis (e.g. with the look–see of the colonies over the site and the whole method every 3 years). First, this serves as a quality population. control exercise to check that the selected colonies However, if all the colonies from one habitat remain representative of the entire population and type cannot be surveyed, any results from other that any trends affecting these colonies are not colonies cannot be extrapolated to the unsurveyed unique but apply to the population in general. habitat without further sampling. For example, if Second, results from detailed surveys of selected you are monitoring a species that occurs on acid colonies should be used as a trigger for a wider grassland habitats in open ground and acid grass- survey if a decline in numbers is observed. If base- land on ledges surrounded by cliffs and all the cliff line surveys have not been conducted on the remain- sites are inaccessible, then the results of the survey ing colonies, you cannot be sure that a decline in the are only strictly applicable to the grassland, not to selected colonies is indicative of a decline in the the entire species population. If this problem is population as a whole; more surveys would be unavoidable, supplementary data should be col- needed to determine this, which would result in a lected on other sites. delay before remedial action could be taken. If the colonies to be surveyed must be selected by judgement, then care must be taken to include sites Data analysis and interpretation that are representative of the entire distribution of If several colony locations have been selected by that species, thus including the whole range of habi- using random or stratified random sampling then tat types and environmental factors that may affect conventional statistical analysis can be carried out that species. Again using cliff sites as an example, it with standard tests (Part I, Section 2.6.4). Given that may be possible to conduct a less intensive survey on it is unlikely that colonies will be the same size, that habitat, such as a ground-based surveillance results must be expressed in a standardised way with binoculars, which at least yields some data (e.g. shoots per square metre, flowers per stem, from that habitat type. Any information regarding etc.) to enable comparisons to be made. environmental influences can be used to supple- If only a single colony is surveyed and moni- ment the floristic survey, particularly when compar- tored, results indicating a decline in the health of ing inaccessible sites with surveyable sites. These the colony should be used to trigger immediate factors can then be used to help explain any differ- monitoring of other colonies. ences in population size between samples, and may highlight the need for more detailed surveys. 15.2.4 Demographic techniques If the habitat type (e.g. blanket bog) is particularly fragile, there is good reason to locate the sam- Principles pling site at the edges of the habitat (although far Demographic surveys of plant populations involve enough into the habitat to avoid sampling transi- following individuals throughout their entire life tional vegetation or areas subject to edge effects) to history. The aim is to understand the life history avoid damaging the vegetation by trampling. and longevity of the species and the factors that Colony population size can be estimated by using affect various stages of the life cycle. The type of the look–see method (Section 15.2.1), systematic information that can be obtained includes: 316 15 VASCULAR PLANTS

* longevity of individuals; sufficiently short, the location and outline of the * growth patterns of rhizomes; plants can be traced with a pantograph or by using * percentage recruitment from seedlings; the grid as a guide to sketch by eye while standing * percentage recruitment by vegetative reproduction; over the quadrat. Alternatively, a ‘mapping table’ * length of time an individual remains fertile; and can be used. This is a sheet of Perspex, mounted on * mortality rates at different growth stages. legs, which is placed directly over the quadrat. The positions of plants are marked on the perspex with Demographic data can be correlated against a felt-tip pen while looking vertically down on to environmental factors (e.g. grazing, rainfall, tem- the quadrat. Once all plants have been marked, the perature) to determine which factors significantly pattern of plant locations can be traced from the affect the population. They can give powerful perspex on to paper for permanent recording. insights into population structure, which can be Accuracy is important when using methods such of key importance for understanding the conserva- as this to map individuals, particularly if the den- tion requirements of species and the effectiveness sity of individuals is high; it will be necessary to of management regimes. Management can then relocate each individual on later surveys. be tailored to protect the vulnerable stages in the Individuals can be marked by a variety of meth- life cycle. ods (e.g. numbered posts, canes or plant labels). If Demographic studies are time-consuming and the plants can be individually identified, the per- expensive; there are relatively few examples of formance of each plant (e.g. survival, growth rate such studies in the literature. One example is the etc.) can be measured. Mapping the outlines of the long-running research by Hutchings (1987a,b)on individuals will allow the calculation of their basal the Early Spider Orchid; the method used for this areas. If all individuals in the sample area are being study can be applied to all species. mapped and marked for compiling a total count, Owing to the high costs of the method, demo- new individuals will be detected during each graphic studies are only likely to be used for mon- repeat survey, which can then be added to the itoring the highest-priority species. It is only map (Bullock, 1996). However, it can be difficult feasible to monitor a subset of the population by to tell whether plants have died and been replaced using this technique (unless the population is by new individuals unless the site is visited very small), so resources should also be allocated regularly. to less intensive monitoring of the rest of the Aerial photographs form a useful supplement to population. ground surveys when initially locating individual large trees. Field methods The actual data recorded will depend upon the Surveys are usually conducted annually, or more objectives of the survey. In many cases, presence– regularly if dormancy occurs (Sanger & Waite, absence data of individual plants may be suffi- 1998), at flowering or fruiting time to collect the cient. In addition, data on the plant characteristics maximum amount of data. such as size can be recorded, including height A permanent plot is established (see Appendix 5) (non-flowering and flowering shoots), cover, num- and the location of every plant within the plot is ber of leaves in basal rosettes, length of stolons mapped. The appropriate mapping method between rosettes, number of flowers, etc. For depends on the scale of the study and the density details of methods for recording tree condition of the target species. Plants can be mapped within see Part II, Section 6.5.2. permanent quadrats by fixing a scale on to the These measurements are repeated on a regular frame or dividing the quadrat into a grid and deter- basis, typically annually or more frequently (e.g. on mining co-ordinates in relation to the frame by a monthly basis) to monitor the fate of individual using rulers or measuring tape. If the quadrat is plants through a season. Counts of individuals at small enough (e.g. 1 m2) and the vegetation is every stage of the life cycle such as seedling, 15.2 General methods 317

vegetative, flowering and senescent should also be Fixed-point photography in particular (see Part II, made. Alternatively, proxy measures of age such as Section 6.1.4) is useful for providing a perma- size can be recorded. Environmental variables such nent pictorial record of successional habitat as rainfall and temperature can also be directly changes on a site over time, and can also be applied measured. The equipment recommended for field to monitoring colonies of small plants if individual surveying and monitoring is summarised in quadrats are photographed. For example, lichens Appendix 6. (Chapter 12) are commonly monitored with fixed- point photography. Data analysis and interpretation Spatial distribution maps or tables should be pro- Field methods duced on an annual basis (or perhaps more fre- A detailed discussion of the methodology for quently for species that exhibit dormancy), to fixed-point photography is provided in Part II, enable the life history of every individual to be Section 6.1.4. recorded and analysed. These are compiled from It is important that the following are noted: the co-ordinates of individuals and will give infor- * date and time of day that the photograph is taken; mation on the longevity of individuals and the * stance, location and direction faced; growth patterns of rhizomes. In addition, elasticity * film speed used (SLR camera); and matrices can be used to assess mortality rates at * an idea of scale, such as a tape stretched out along different stages in the life cycle, to identify key the horizontal axis. stages that determine the structure of the population. The analysis of demographic studies and in Photographs should be taken with a record of the particular the use of elasticity matrices is highly quadrat number and location positioned in one complex and for this reason is not described in this corner. Dry-wipe boards are very useful for this Handbook. Further information can be obtained purpose, as it is easy to change the information from Hutchings (1987a,b), Wells & Willems for each quadrat. (1991), Watkinson (1986) and Sanger & Waite Individual plants can be marked in the field to (1998). Information on the management of species assist the interpretation of the photograph (see exhibiting dormancy can be found in Farrell (1991). Section 15.2.2). The extent of a colony can be highlighted by running a tape around the edge. 15.2.5 Photography Alternatively, it may be useful to use Polaroid prints as these can be annotated in the field with Principles felt-tip pens. However, they tend to be of poorer Photographs can enhance the accuracy of a survey quality and can also fade with time unless kept in by reducing the error involved in the relocation of light-proof storage. permanent sample points. They can also provide Tripods are a valuable aid in poor light and for helpful information such as an impression of the close-ups and are essential for fixed-point photo- density of the plants, or the height or structure of graphy. Prints can be laminated for field use and the vegetation. Photography can be a quick way to can considerably aid the relocation of sampling record the presence and extent of an entire popula- points. Appendix 6 lists the essential field tion, although it cannot provide a substitute for equipment. conducting on-site counts and the information provided is largely qualitative rather than quantitative. Data analysis and interpretation Photographs can also record seasonal advance- Total counts should not be made from photographs ment to aid comparisons of data with other years, unless the detail is sufficient to distinguish indivi- the degree of events such as poaching and grazing, dual plants. and other variables such as the amount of bare Diagrams showing the position and size of the ground and vegetation height. colonies can be traced from fixed-point photographs 318 15 VASCULAR PLANTS

and used as overlays. Provided that appropriate sam- The purpose of the programme is to build a clear pling has been used, estimated colony areas from picture of the state of the UK flora by carrying different photographs can be analysed statistically out a range of surveys to identify changes and by using standard tests (Part I,Section2.6.4). trends in the UK’s wild plant species. This information will then be used in the development of appropriate conservation management plans, 15.3 VASCULAR PLANT CONSERVATION which will respond to the changes and promote EVALUATION CRITERIA a healthy environment for wild plants. Four sur- Key evaluation considerations veys are being run, which have been designed to cater for people’s differing botanical skills. The status of the British flora has recently been These are: reviewed by Rich200 1(). In the British Isles, there * Annual single-species survey; are currently about 1390 native seed plants and * Common Plants Survey; ferns (c. 2200 including named critical species in * BSBI Local Change survey; Hieracium, etc.), and over 1100 reasonably well- * Rare Plant Recording. established aliens. There are c. 450 endemic species in the British Isles (c. 20% of the flora) mostly con- Further details on the results of the surveys and tained in the critical genera such as Sorbus and how to participate in forthcoming surveys can be Taraxacum, and 10 non-critical species and 29 ende- found on Plantlife’s website at www.plantlife. mic subspecies (Rich et al., 1999). org.uk/html/about_plantlife/about_index.htm. The UK also holds internationally important Individual species of vascular plant are included plant assemblages such as oceanic western and in several current conservation programmes. In Atlantic–alpine communities. The UK has a respon- 1993, Plantlife International launched Back from the sibility for species for which the country has a large Brink, a programme designed to halt species loss and proportion of the world’s population. For example, decline in Britain. Twenty-one flowering plants in between 25% and 49% of the world’s Bluebell Great Britain and eleven in Ireland (excluding criti- Hyacinthoides non-scripta population is found in the cal species) have been lost since detailed records UK. Furthermore, a number of the UK’s flowering began, although this is only a fraction of the number plants are growing at the edge of their range, some that have suffered population crashes and are still recognised as endemic subspecies. declining owing to the pressures of agricultural The Botanical Society of the British Isles (BSBI) is intensification, habitat neglect or destruction. In the largest organisation devoted to the study of 1995, the UK BAP identified a further 168 plant botany in the British Isles. It produces national species threatened with extinction or severe atlases and county floras of the distribution of decline. A total of 101 species are in the Back from plants, most notably the recent New Atlas of the the Brink programme, with more than 40 species British and Irish (PrestonFlora et .,al 2002a), the firstprojects operating in England, Wales and Scotland. comprehensive update of the distribution of vascu- The programme combines laboratory and field lar plants in Britain since 1962. The 2002 atlas research with hands-on management to produce provides colour maps for over 4000 taxa, showing effective, practical action for rare plants. More infor- native and alien distributions, in three date classes, mation on the programme and the list of Back from for every 10 km square in Great Britain, the Isle of the Brink species can be found on Plantlife’s website: Man, Ireland and the Channel Islands. www.plantlife.org.uk/. The BSBI has joined forces with Plantlife, dedi- English Nature’s Species Recovery Programme,a cated to conserving all forms of plant life in its programme of action for bringing threatened spe- natural habitat, to deliver the exciting and innova- cies back from the brink of extinction, includes tive programme Making it Count for People and Plants, species listed in AnnexII/IV of the Habitats which is supported by the Heritage Lottery Fund. Directive, as well as UK BAP species, the IUCN Red 15.3 Plant conservation evaluation criteria 319

List for Britain and nationally scarce species for 2. Check existing designation status of the site. For which it has been proven that they would be threa- EIAs, the search area should extend to 2 km from tened by a drastic decline in range or numbers. the boundary of the site. This will inform the Species and sub-species endemic to Britain are results of the preliminary scoping survey and also included, as well as ones found in only one or highlight any areas of land that hold species of two other countries. The programme uses similar conservation importance. techniques to the Plantlife Back from the Brink pro- 3. Carry out a preliminary (scoping) survey to gramme (which it sometimes funds in part) to identify the potential for species of conserva- further the conservation of these species. Further tion importance. A Phase I habitat survey (see information and a list of species included in the Section 6.1.4 for methodology), augmented by programme can be found on English Nature’s land management information, should identify website at www.english-nature.org.uk/science/srp/ habitat types that may potentially hold such spe- default.asp. cies. For example, arable land on an organic farm At The Hague in April 2002, the ‘Global Strategy with wide cereal margins may hold one or more for Plant Conservation’ was endorsed by the parties rare UK BAP arable weeds. to the Convention on Biological Diversity, the long- These three steps should enable the determination term objective being to halt the continuing loss of of Valuable Ecosystem Components (VECs) (in plant diversity. Sixteen outcome-orientated, global terms of vascular plant species) that may potentially targets for plant conservation were set, to be com- be present. To establish the actual presence or pleted by the global community by 2010. The UK is absence of a VEC, further survey may be necessary committed to implementing the strategy and the at an appropriate time of year. Plant Diversity Challenge (JNCC, 2004) report is its A further key consideration is the viability of the response. The sixteen targets are grouped under population of any species of conservation import- five objectives: ance. A small population of a nationally important species may rank lower than a large, ecologically 1. Understanding and documenting plant diversity; viable population of a regionally important spe- 2. Conserving plant diversity; cies. However, the nationally important species 3. Using plant diversity sustainably; may be so rare in the UK that all occurrences of 4. Promoting education and awareness about plant the species are to be conserved. diversity; Currently there is surprisingly little conserva- 5. Building capacity for the conservation of plant tion emphasis on either endemics or rare critical diversity. species in large genera such as Hieracium and Each of the major partner organisations (JNCC, Taraxacum in Britain, despite the SSSI selection Plantlife International and the Royal Botanic guidelines (see below). Advice should be sought Gardens, Kew) has a remit to look after a particular about the likely occurrence of such taxa in any group of targets. Further information on the strat- area of search. egy can be found on the JNCC website at www.jncc.gov.uk/species/Plants/default.htm. The report can also be viewed or downloaded from Protection status in the EU and UK this site. Appendix 1 of the Bern Convention lists nine The key considerations with regards to evaluat- vascular plants native to Britain and threatened in ing vascular plants at a site are listed below. Europe as a whole, for which special protection is 1. Check lists of species of conservation importance required. They are all included on Schedule 8 of the and their protection status (see below for informa- Wildlife & Countryside Act. AnnexIIb of the EU tion on which lists to check and where to obtain Habitats Directive contains the same nine vascular the relevant information). plants as in Appendix 1 of the Bern Convention. 320 15 VASCULAR PLANTS

For these species, the Directive specifies that InS additionpecial to IUCN criteria, there are also criteria Areas of Conservation (SACs) will be designattoed. defineThe nationally rare and nationally scarce. same species are also listed in Annex IVbCurrently of the these are defined to be: Nationally Rare Directive, requiring their strict protection. As (NR),such occurring, in 15 or fewer hectads (a hectad is a the species are protected in Britain under 10both km Âthe10 km square of the National Grid) in Wildlife & Countryside Act (1981, as amGreatended Britain;) Nationally Scarce (NS), occurring in and the Conservation (Natural Habitats, &16–100 c.) hectads in Great Britain. Regulations. A list of the vascular (and non-vasThecula vascularr) plants include the flowering plants plants listed under international agreements casan wellbe as conifers, ferns and allied species. Vascular found on the JNCC website at www.jncc.gplantsov.uk/ have been assessed against 1994 IUCN criteria species/Plants/p6_3.htm. by Wigginton1 99(9) but require revision against the In Britain, all wild plants are p rotected2001 agai criteria.nst More recently, the distribution of all unauthorised upro otingn deru Section13 of the vascular plants has been mapped by et Pr.aelston Wildlife & Countr yside A ct (1 98 1, as(2 00am2a).e ndedThis). has also critically reviewed the native Plants listed on Schedule 8 of the Act enjoystatus special of species; only those species that are consid- protection against picking, up rooting, destructionered as native or archaeophytes are given a conser- and sale. The Schedule is reviewed every fivevation year status.s, The publication of the New Atlas has but currently it contains7v as10cul arplants,33bryo- substantially updated knowledge of species distribu- phytes, 26 lichens and 2 charophytes (stoneworttion ands) declines and has resulted in a considerable (JNCC, 20 04). The list of vascular (and nonnumber-v ascul ofar) species being listed as rare or scarce for plants currently on Schedule 8 of the Wildlife & the first time. Some of these species may warrant an Countryside Act can be viewed on the JNCC website IUCN designation, but as yet they have not been at www.jncc.gov.uk/species/Plants/p5.htm. assessed against IUCN criteria. The most recent Section 74 of the CRoW Act requires the Secretary date class (1987–99) has been used to assess rarity of State for England and the National Assembly for status, except when taxa are known to have been Wales each to publish a list of species and habitat under-recorded. Vascular (and non-vascular) plants types that are of principal importance for the listed under the various IUCN threat categories and conservation of biological diversity in England Nationally Rare or Scarce can be viewed on the and Wales, respectively. The Section 74 list for JNCC website at www.jncc.gov.uk/species/Plants/ England can be viewed on the DEFRA web page threatened/default.htm. www.defra.gov.uk/wildlife-countryside/cl/habitats/ Following the publication of the Red Data Book habitats-list.pdf. The equivalent list for Wales can for vascular plants in Britain, the Threatened Plants be viewed on the National Assembly for Wales web Database was initiated to create a ‘live’ database of page www.wales.gov.uk/subienvironment/content/ records of threatened plants. A joint venture between guidance/species-statement-e.htm. These two lists the statutory nature conservation agencies, BSBI and are based on UK Bio-diversity Action Plan (UK BAP) Plantlife, the database is intended to contain infor- Priority Species and Habitats lists. Further informa- mation on the state of populations of threatened tion on the UK BAP process and the current list of species and hence to inform conservation initiatives UK BAP species and habitats can be found on the UK such as the UK BAP programme. More information BAP website at www.ukbap.org.uk/. on the database and a list of the 400 or so plants included in the project can be found on the BSBI Conservation status in the UK website at www.bsbi.org.uk/html/tpdb.html.

The assessment of conservation status for species, Site designation criteria including the IUCN criteria for assessing threat status, has led to the publication of Red Data SSSI criteria for designating a site for its vascular plant Books for a range of taxa in a number of countries. interes t are described by1989 NCC an d ( subsequent 15.3 Plant conservation evaluation criteria 321

amendments), which can be found on the JNCC web- ideally follow the guidelines presented in Part I of site at www.jncc.gov.uk/Publications/sssi/default.htm. this Handbook. These recommend grading the Briefly, sites are considered for selection on the basis importance of sites or components thereof against of their vascular plants on the following criteria. the following levels of value: 1. All sites with viable populations of a Wildlife & 1. International; Countryside Act Schedule 8 species should be 2. National; selected. 3. Regional; 2. The localities of all Red Data Book species are to be 4. County/Metropolitan; considered as candidate sites. Various criteria 5. District/Borough; determine whether a site qualifies for selection 6. Parish/Neighbourhood. based on the presence of one RDB species. The guidelines take into account the size (and 3. A simple scoring procedure is used to assess com- therefore viability) of populations of species when binations of species within the two classes attempting to rank these against each other. Part I Nationally Rare and Nationally Scarce (i.e. occur- of this Handbook also provides information on other ring in 1–100 10 km squares). With this scoring methods for ranking the importance of species and system, the presence of two RDB species, for exam- habitats. ple, qualifies a site for selection. Vascular plants found on a site should be evalu- 4. The largest population of endemic species in each ated in relation to the species listed onII Annexes area of search (AOS) should be selected. and IV of the EU Habitats Directive, which are of 5. In each AOS, the best population of each of the six international importance. In terms of national non-endemic species threatened in Europe, which importance, the UK BAP (Section 74) Priority are neither listed on Schedule 8 of the Wildlife & Species list should be consulted, as well as the Countryside Act nor RDB species, should be selected. national Red Book for vascular plants (Wigginton, 6. If an AOS contains species that are known to have 1999) and Scarce Plants in Britain (Stewart et al., 1994). declined markedly within Britain but are not yet Reference should also be made to the JNCC list in the Nationally Rare or Scarce categories, parti- of threatened plants (www.jncc.gov.uk/species/ cularly large populations may be selected. Plants/threatened/default.htm) and the SSSI selec- 7. Floristic assemblage: sites with more than 75% of tion guidelines (NCC, 1989). the total vascular plant species list for a commu- Below the national level of importance, the spe- nity type of the NVC should qualify for selection. cies list for a site should be checked against County 8. All microspecies and recognised, regularly occur- Red Data Books, where they exist. Local biodiver- ring hybrids should be represented on at least one sity partnerships may also have published, through SSSI somewhere in Britain. the production of local BAPs, lists of species of local Further information on each of the above criteria conservation importance that, if available, should can be found in NCC (1989). also be used for evaluation purposes. Guidelines for the selection of sites of conservation import- Evaluation of vascular plants ance at a County level, available from the Local Authority or local Wildlife Trust, may include The evaluation of Valued Ecosystem Components criteria based upon particular vascular plant (VECs) (both species and habitats) for EIAs should species. 16 * Dragonflies and damselflies

Dragonflies and damselflies (Odonata) have an 16.1.2 Population size (larval and adult) aquatic larval stage, which can last for a few years, followed by emergence, mating and dying The dragonfly and damselfly life cycle has three all in the same season. As larvae can live for long stages (the egg, an aquatic larval stage and a terres- periods before pupating, an absence (or decrease) trial adult stage) but only two of these, the larval and of adults in one year does not necessarily imply adult stages, are of value in monitoring. Monitoring that the population is in decline. Several years of populations of Odonata can therefore entail the negative results are required to confirm an monitoring of either or both of these. In general, absence. populations of adult Odonata are estimated either Surveys of Odonata can provide a useful indica- from the number of exuviae (discarded exoskeletons tor of water and habitat quality where regional of the larvae) found on emergent vegetation or by differences in diversity are taken into account. counting adult males as they display over water. This is one reason why they are a useful group to Larval populations can be sampled as part of general survey as part of EIA studies. aquatic invertebrate monitoring (see Chapter 20). Monitoring areas of suitable habitat may be appropriate, particularly if resources are not available for more detailed survey methods. Monitoring 16.1.3 Population structure of micro-habitats is not specifically covered in this For a population to be deemed viable there must be Handbook. However, some of the techniques in Part II sufficient recruitment from the larval to the adult may be adapted for this purpose. stage and sufficient successful breeding to establish a new generation of larvae. 16.1 ATTRIBUTES FOR ASSESSING The successful recruitment of adults from the CONDITION larval stage may need to be monitored for rarer species. This can be estimated from a comparison 16.1.1 Population range of larval counts with counts of exuviae. Mortality of adults will reduce the number of newly emergent Area of occupancy is an important attribute to adults that return to breed in the following year. monitor and can be best assessed by mapping pre- Comparison of year-to-year counts will reveal sence – absence in suitable micro-habitats. Note trends in larval and adult mortality. that presence in the only pond in a 100 ha site gives 100% occupancy, even though most of the site lacks the species. At the same time, a presence 16.2 GENERAL METHODS in 50 ponds in the same area is only 50% occupancy if there are 100 ponds. Area of occupancy must General site survey methods for invertebrates are therefore be defined in terms of the area of suitable provided in Chapter 10. micro-habitat occupied. Repeat surveys will illus- The general methods for surveying and monitor- trate expansions or contractions of range. ing Odonata are outlined in Table 16.1.

# RPS Group plc and Scottish Natural Heritage 2005. Can only be carried out during certain weather conditions Depends on method chosen; possible health and safety implications for some water bodies Number of exuviae not necessarily a good estimate of adult population returning to breed, though it allows a good year-on-year comparison Can only be carried out during certain weather conditions parable results to be taken from different observers Good for EIA method chosen but invariably will be weather independent ken in most weather conditions except very windy or wet weather counts for small ponds Good for EIA Expertise required Advantages Disadvantages Some ecological knowledge required for species-specific work Identification Enables com- Identification Depends on Identification Can be underta- Identification Gives total Gives reliable counts of only adult males and tenerals Depends on method chosen Number of exuviae counted will depend on density of vegetation and ease of access to waterside Gives reliable counts of only adult males and tenerals If conditions are ideal, results should be reasonably precise Depends on method chosen Good in theory If conditions are ideal, results should be reasonably precise rain is easily traversed Depends on method chosen May be time- consuming if dense vegetation must be searched Best for small areas or difficult terrain Population size data Efficiency Precision Bias absence absence Index Estimate Estimate estimate Recommended species group Odonata Index Good if ter- Odonata Presence– Odonata Presence– Odonata Index or ) Methods for surveying and monitoring dragonflies and damselflies 20 (see Sampling larvae Chapter Table 16.1. Transects Exuviae counts Timed counts

323 324 16 DRAGONFLIES AND DAMSELFLIES

the surveyor will therefore affect the accuracy of 16.2.1 Sampling larvae counts. As a compromise measure, counts of exu- Odonata larvae should be sampled by using the viae should be made each day, removing each one as techniques described for aquatic invertebrates it is encountered so that subsequent counts do not (Chapter 20). The appropriate method will depend duplicate numbers. on the time and resources available and the level of However, exuviae counts will at best provide detail required. In general, it will probably be suffi- only an index of the emergent adult population in cient to sample by using netting (Section 20.2.2)or one year. kick sampling (Section 20.2.3), although dredging bottom mud and taking weed samples in addition Field methods will often yield a higher count. Only final-instar Surveyors should walk around the water body, clo- nymphs – those in which the wings reach to or sely examining emergent vegetation for exuviae. beyond the rear margin of the third abdominal Those that are found should be collected for later segment – can be identified reliably and even with identification to species level where technically these it is not possible for all examples to be iden- possible. If it is not practicable to survey the entire tified to species level. Identification from exuviae water body margin in the time available for the is possible with similar limitations. The keys in survey, either survey a fixed length of bank or Askew (1988) should be used, as some other search for a fixed length of time on each visit. British keys are unreliable. This will standardise observations and enable valid comparisons to be made. Surveyors should be experienced in the recogni- 16.2.2 Exuviae counts tion of exuviae and be aware of the likely places where they can be found. To increase the likeli- Principles hood of finding exuviae it may be desirable to Odonata emerge from the larval stage on plants or place sticks or other artificial supports around the objects standing in the water body or around its water-body edge at regular intervals to encourage edges. The larval skin splits open and the adult emergence in accessible areas; these sticks can be emerges; the empty larval skins (exuviae) remain more easily searched but care must be taken to on the plants or objects and can be counted. place them at the appropriate angle (see above for According to Askew (1988), libellulids, cordu- details on adult emergence positions). However, liids and some gomphids use horizontal supports even if sticks are used, the vegetation should still with the head only slightly raised; aeshnids hang be thoroughly examined. between 908 and 1808 to the vertical so that they Timing and frequency of counts will depend upon are belly-up (i.e. on the underside of sloping sur- availability of resources and the species being moni- faces) and all European Zygoptera hang head tored. Moore & Corbet (1990)recommendthat upwards from a near-vertical surface. counts should be made weekly. However, this is not If all the exuviae at a particular water body could likely to be feasible unless visits can be integrated be collected and identified in a year, the total would with other monitoring work. Visits can be timed represent the size of the emergent population from to coincide with the emergence of a particular spec- that water body in that year. However, it is likely ies of interest; otherwise you should aim to visit at to be impracticable, if not impossible, to count all similar times each year, or every 3 years, depending the exuviae because, although they can remain on onthedegreeofaccuracyrequiredfromthestudy. vegetation for some weeks if undisturbed, they can Frequency and timing of visits should be standar- be dislodged and lost during rainy or windy condi- dised once a survey and monitoring regime has tions. In addition, surveyors can easily miss exuviae, been decided upon. If weekly counts cannot be particularly those of damselflies. The nature of the made, a problem may arise when attempting to habitat and the accessibility of the water margin to standardise survey timing: the date of the peak 16.2 General methods 325

population will vary from year to year depending on in isolation are still a useful and relatively simple weather conditions. Therefore, a count made on the index of population size. same date each year may produce very different estimates of similar population sizes. Surveying 16.2.3 Transects only during periods of suitable weather conditions (see below) and attempting to survey at a similar Principles seasonal time each year will help to mitigate this Adult Odonata are highly visible and relatively easy bias. However, weekly counts are preferable, because to identify in the field. A standard technique involv- this enables the peak count to be identified. The ing transect walks along water body edges has been equipment required for surveying and monitoring developed (RSPB/EN/ITE, 1997). This method is par- in the field is listed i n 6. A ppendix ticularly suited to damselflies and libellulid dragonflies (Brooks, 1993) and allows different observers Data analysis and interpretation following a set route to produce comparable results. If several counts of adults are made in one year, the In general, it is only adult males that display over data can be summed to provide an estimate of water, and then only at times when air temperature the total number of adults emerging. In practice, is high. Adult males at other times, females for most this should be treated as an index, rather than an of the time and immature adults of both sexes are actual estimate of population size. Time con- generally found away from water. The only mean- straints will generally mean that only a proportion ingful counts of mature adults are of adult males by of each year’s exuviae will be collected. water during good conditions (Moore & Corbet, Provided that sampling is representative, data 1990). Teneral adults (adults that are less than a can be analysed statistically by using standard day old with wings and body still soft) can also be tests (Part I, Section 2.6.4). Other kinds of statistical counted; these tend to fly away from water after analysis may also be appropriate (see Section 2.6.4). emergence but do not travel far on their first flight. It is important to consider that exuviae counts Teneral adults near a water body are therefore very only provide a partial picture of the size and health likely to have emerged from that water body and of a population. If counts are falling, the decrease can be counted separately from adults to estimate could be due to mortality of adults (not surviving to numbers of newly emergent Odonata. breed) or of larvae (not surviving to emergence). Adult Odonata do not survive over winter; they Field methods breed in the same season of emergence. Therefore, Set routes for transect locations should be identi- the exuviae count for one year gives the potential fied, mapped and divided into sections before sur- number of breeding adults in that year. Most dra- veying commences. Counts should be made at gonfly larvae take more than one year from hatch- regular intervals, and at the same time each day ing to emergence, so adults laying eggs in one year during optimal conditions for recording Odonata. will not produce the next year’s final-instar larvae. Maximal numbers of Odonata are found over water Therefore the count of exuviae from one year is not within an hour or two of midday on warm days related to the previous year’s count. Knowledge of with little or no wind (Moore & Corbet, 1990), the ecology of individual species is required to iden- although these data probably apply to southern tify which year of adult counts relate to which year Britain. Surveys should take place between 10.00 of larvae. The situation is further complicated by the and 14.00 hours on days when air temperature in fact that larvae can ‘lie over’ (i.e. not emerge) in the shade is above 17 8C, there is at least 50% sun- unfavourable seasons; the life cycle is not necessa- shine and wind conditions are light (if trees are rily completed in the same length of time. bending, the wind is too strong). It is permissible In order to examine further any trends iden- to vary these parameters to accommodate local tified with exuviae counts, surveys of adults and climatic conditions provided that repeat surveying larvae will be required. However, exuviae counts in subsequent years is carried out under the same 326 16 DRAGONFLIES AND DAMSELFLIES

conditions. All these conditions should alsonot easilybe walked because of uneven terrain or recorded alongside the insect counts. dense vegetation, or if it is too small (i.e. small Surveys can also be directed at particular ponds)species; to require transects. The principles of sur- in this case, s urveys can b e t imed to cveyo inci timingde with and applicabilitythe are identical to those flying period of that species ( setee al, M19. erritt96). for transects, except that surveys are carried out for The transect should always be walked aby set periodthe of time while remaining in the same same route, at a continuous slow speed, place.keeping to the edge of the water body. In each section of the transect, every identifiable specimen is recordedField methods (flying or perched) in front of and to theSome side ponds of may be small enough to be surveyed in (but not behind) the surveyor. It is recommendedtheir entirety from one location. Larger areas may that transects should be walked every week requireduring sample points at regular intervals. In this the summer period: 1 May to 30 Septembercase, (Moore points should be far enough apart to avoid & Corbet,199 0; RSPB/EN/ITE,199 7). If time con-counting individuals twice. If you walk all the way straints do not allow this, visits from differentaround a lake, you may encounter individuals that years to the same site should be made at similar were counted earlier on the far side and so be times to enable comparable data to be collected. counting the same one twice. A section or sections Appendix 6 lists the necessary field equipment.of bank should be selected very carefully: some dragonflies can move a long way and often feed Data analysis and interpretation over the entire surface area of a lake. Length of If transects have been regularly surveyed during counts at each point should be standardised; one field season, the maximum count of adult given that Odonata are highly mobile, a short males can be taken as an estimate of the breeding count duration is preferable, since it is less likely male population. If site visits have been less fre- that individuals will be counted more than once. quent, data can only reasonably be interpreted as The timing and suitable conditions for timed an index of population size. Data can be expressed counts are the same as for transects (Section as the number of individuals per metre or per 16.2.3). The surveyor should stand in the same transect and multiplied by the total length of spot, regularly scanning through 3608 and record- water body margin to obtain an estimate of the ing all individuals seen (flying or perching). You total population at that site. should try not to count the same individual twice, Provided that sampling is representative, data but this may be unavoidable if counts are under- can be analysed statistically by using standard tests taken over longer periods. For flowing waters, such (Part I, Section 2.6.4). Comparisons within one year as rivers, directional counts are useful. The num- of exuviae counts (Section 16.2.2), teneral adult bers seen flying downstream plus numbers flying counts and adult counts can give an indication of upstream gives the maximum possible count. adult mortality if it is possible to sex exuviae and Numbers flying upstream minus those flying tenerals. Exuviae are sexable if the gonapophyses downstream (or vice versa to obtain a positive num- are undamaged; this is usually the case, but the ber) gives the minimum. The recommended field careful detachment of exuviae from surfaces is equipment is listed in Appendix6. required. Teneral adults are sexable but must be captured: this may prove impracticable in reality. Data analysis and interpretation Data analysis is carried out in a similar manner to 16.2.4 Timed counts that for transects (Section 16.2.3). However, if a site is small enough to be surveyed from one point, Principles numbers from that count can be taken as an esti- Timed counts are an alternative to transect counts mate of the male breeding population rather than (Section 16.2.3) and can be useful if the habitat is as an index. 16.3 Odonata conservation evaluation criteria 327

The Southern Damselfly is currently the only 16.3 ODONATA CONSERVATION priority BAP species. EVALUATION CRITERIA

16.3.1 Key evaluation considerations 16.3.3 Conservation status in the UK

Around 38 species of dragonfly (including damsel- Four species are classified as endangered in the flies) breed in Britain. Some are supplemented by British Red Data Book (Shirt, 1987), but are all con- migrants from the continent, which can bring sidered extinct apart from the Norfolk Hawker. large fluctuations in abundance of a species Two species are classified as Vulnerable and three between years. In addition, there are species that as Rare in the British Red Data Book. are colonising Britain (or possibly recolonising after a long period of absence), such as the Small Red-eyed Damselfly Erythromma viridulum. 16.3.4 Site designation criteria The last BRC atlas covering the dragonflies of SSSI criteria for designating sites for dragonfly Great Britain and Ireland was produced in 1996. interest are described by the NCC (1989). In brief, Since then, the Small Red-eyed Damselfly has started all sites supporting populations of endangered spe- breeding and spreading in England, and other species qualify for selection. Sites containing a single cies that were previously occasional migrants have Nationally Rare or Scarce species can qualify if the also started to breed here in recent years. The British site supports: Dragonfly Society has accumulated survey data since the atlas was published. It is therefore important to * the largest population of the species in the area of consult local record centres and naturalist societies search; for up-to-date information on recorded dragonfly * a strong population of the species on a site sup- distribution for a particular area. porting a good example of a habitat type; * a strong population of the species within an area of search that encompasses a substantial propor- 16.3.2 Protection status in the UK and EU tion of the localities for the species; or * a strong population at the edge of the species No dragonfly species are listed in Appendix III of geographical range. the Bern Convention. Two species are strictly protected under In addition, where a site has a number of species Schedule 5 of the Wildlife & Countryside Act 1981 that meets or exceeds a number considered to form as amended by the Countryside & Rights of Way Act an outstanding assemblage, the site should be con- 2000: the Norfolk Hawker Aeshna isosceles and sidered for selection. This number varies across Southern Damselfly Coenagrion mercuriale. Britain: 17 – 15 species for southern England and The Southern Damselfly is the only species still Wales, 9 in Scotland, and fewer in the surrounding occurring in the UK that is listed in Annex II of the islands. The site to be selected should include semi- EU Habitats Directive of species of community natural habitats used for resting and feeding in interest whose conservation requires the designa- addition to the water body that provides the breed- tion of Special Areas of Conservation (SACs). The ing site, and some of the associated catchment if Orange-spotted Emerald dragonfly Oxygastra curtisii that is necessary to protect the supply and quality is also listed, but is considered extinct in Britain. of the water (NCC, 1989). 17 * Butterflies

Butterflies are mobile and often highly visible 17.1.2 Colony numbers species. Some species exhibit a metapopulation Butterflies often live in breeding areas defined by structure, with colonies in discrete areas of suit- areas of suitable habitat. Separate breeding areas able habitat. Colonies may become extinct, and may also exist within areas of suitable habitat. The the areas are then recolonised. Failing to find a number of breeding areas on a site is a straightfor- species on a site in one or more years can there- ward indication of the health of a population. The fore not be taken as proof of absence; negative number of breeding areas may also vary with species: results from several years would be needed to some species will occupy a single large breeding area confirm this. and others will form smaller, more discrete popula- Presence–absence of adults is the simplest tion units. A small number of breeding areas on one method for monitoring butterfly populations and particular site does not necessarily imply that a spe- will usually be used to establish baseline data at cies is not at its optimal level, especially if the site is a sites that have not previously been surveyed. More part of the edge of the main area for the species. detailed survey and monitoring of larval or egg Numbers within a breeding area are relatively numbers can be made by using timed counts or simple to establish: presence of individuals can be quadrats and transects once presence has been used to imply the presence of a breeding area. established. For species of conservation import- However, failure to find evidence of a species in ance, some sites will have already been identified one year alone cannot be taken as evidence of and monitoring schemes will normally already be absence; several surveys with a negative result will in place. However, surveys of other sites are be needed to confirm an absence, particularly on obviously required, since it is unlikely that all sites where a species has previously been recorded. breeding areas have been identified, and you will need to look for range expansions out of known sites. 17.1.3 Population size

A more detailed assessment of butterfly popula- 17.1 ATTRIBUTES FOR ASSESSING tions will entail estimates of population size. CONDITION Estimates can be made by counting adults or larvae 17.1.1 Population range along transects set up through areas of suitable habitat. Transect methods may need to be tailored Area of occupancy is an important attribute to sur- to suit particular species. vey and monitor and can be best assessed by mapping presence–absence in areas of suitable habitat. Repeat surveys will illustrate expansions or con- 17.1.4 Population structure tractions of range. Monitoring habitat extent with occasional confirmation of presence may be the For a population to be deemed viable there must be most practical approach in some cases. sufficient recruitment from the larval to the adult

# RPS Group plc and Scottish Natural Heritage 2005. 17.2 General methods 329

stage and sufficient successful breeding to estab- reported that Wall Brown Lasiommata megera larvae lish a new generation of larvae. Butterflies can be in Cheshire feed on Cocksfoot Dactylis glomerata, surveyed at the larval stage by counts on food Wavy Hair-grass Deschampsia flexuosa, Yorkshire plants. Such counts can be compared with adult Fog Holcus lanatus and bent grasses Agrostis spp. but counts to examine changes in population structure not on all of those at any one site, and that differ- from year to year. ences occur between sites. If eggs, larvae or signs of larvae are found then a 17.2 GENERAL METHODS presence is confirmed and a more rigorous monitoring scheme must be devised if abundance data General site survey methods for invertebrates are are required. If nothing is found after a set time provided in Chapter 10. period has elapsed then the species can be classi- Table 17.1 outlines the general methods for sur- fied as absent from that site on that occasion. veying and monitoring butterflies. However, failure to find a species on only one occasion does not imply that it is definitely absent. 17.2.1 Larval or egg counts: timed Butterflies have natural cyclical population pat- searches terns, and in some years they may be numerically common whereas in other years they may be Principles scarce. During these naturally occurring years of Counts of larvae and eggs are a reliable method for scarcity, the few that are around may be absent establishing the presence of butterfly species. from one survey plot, but may return the next Although adult butterflies are often conspicuous, year as their numbers build up again. The effect of they tend to fly only during periods of fine weather. weather is also important: a thorough knowledge Searches for eggs and larvae are less dependent of the ecology of each species is needed as some upon sunshine than searches for adults and are by species can react to adverse weather by not emer- definition carried out at a different time of the year. ging from the pupa (this happened with a lot of It is thus possible to monitor one species by two moths in 1998) but these will certainly emerge in methods at two different times in the same year. the following year. Other species may react in different ways. A single year of absence is not enough Field methods to confirm absence. The number of years required Establishing presence–absence will vary between species and according to the This is a variant of a timed count in that you must reasons for the temporary absence of the life cycle establish an arbitrary time beyond which it is stage being searched for, but it will always requ- decided that the species can be considered absent. ire at least two successive years as an absolute Generally, the surveyor will walk around the site in minimum. a random manner, searching for larvae or eggs; this The surveyor must be familiar with the habitat may require more than one surveyor, because not requirements of the target species and be able to every fieldworker will have sufficient knowledge identify the larval food plant(s) and larvae with of all butterfly species. confidence. If one particular species is being looked for, then it may be possible to narrow down the search area Timed counts considerably if the larval food plant(s) of the spe- Timed counts can be used to produce an index of cies is known. The complete range of food plants larval population size in the form of numbers for several species, especially the grass-feeders, is found per unit time (or per search if search times not known; looking for a species solely on a food are kept constant). To make the most efficient use plant known from one site may result in missing of time, searches should be concentrated on areas the species if it has adapted to different conditions of suitable habitat. This non-randomness means on another site. For example, Emmet 19& 89)H eathatth ( data are not comparable between sites, but 330

Table 17.1. Methods for surveying and monitoring butterflies

Recommended Population species group size data Efficiency Precision Bias Expertise required Advantages Disadvantages

Larval or Larvae Presence– Reasonable Good Inconspicuous Identification Can be carried Does not egg counts: (Northern absence larvae or eggs out in most estimate number timed Brown Argus; Index may be missed weather of adults searches Small Blue, Estimate conditions Not appropriate eggs; Marsh for all species Fritillary, larval webs)a Larval or Larvae Index Good Reasonable Inconspicuous Identification Entire colony Standardising egg counts: (Northern Estimate larvae or eggs areas can be search quadrats Brown Argus; may be missed searched methods may or transects Small Blue, be difficult eggs; Marsh Not appropriate Fritillary, for all species larval webs) Transects Adults Index Good if Will vary Some species Identification Usually reliable Survey times (all species) transect according may be method, which restricted access to weather relatively produces by appropriate straightforward conditions under-recorded comparable weather at time of results conditions survey

a Latin names: Northern Brown Argus Aricia artaxerxes; Small Blue Cupido minimus; Marsh Fritillary Eurodryas aurinia. 17.2 General methods 331

provided survey times are kept constant and pro- and larval or egg density then an estimate can vided that identical techniques are used in the be made of the total number of larvae or eggs. same area of land each year, data can be compared For example, if an average of two Chequered between years from the same site. Skipper larvae are found on each Molinia tussock, Knowledge of the timing of larval emergence the tussocks are on average distributed at two per and their habitat and food preferences is essential square metre and cover an area of 100 m2 then to make good use of survey time. Surveys will in all the total number of larvae can be estimated cases need to be tailored to suit the life cycle as 2 2 100 ¼ 400. Confidence intervals can of the target species, and the counting methodol- also be estimated under appropriate sampling ogy may also depend upon the ecology of the spec- conditions. ies concerned. For example, when counting Marsh Fritillaries Euphydryas aurinia you should count lar- 17.2.2 Larval or egg counts: quadrats and val webs rather than eggs (Section 17.3.1), whereas transects for the Chequered Skipper Carterocephalus palaemon you should select a transect including at least 50 Principles Purple Moor-grass Molinia caerulea tussocks close to Transects or quadrats can be used for monitoring the transect used for monitoring adults (Section larval or egg numbers. Transects can be laid out 17.2.2). across areas of representative habitat, or quadrats The habitat should be searched thoroughly dur- can be selected and sampled. Unless a large quadrat ing the survey, and signs of egg and larval presence size is used, most quadrats will only contain part of should be noted and counted. It should not be one or two clutches of eggs. These data will be of necessary to take samples from the field; with limited use for estimating population size, but will rare species this is obviously undesirable. Often it provide supplementary information for estimating will also be desirable to estimate the area covered clutch size, which will be of use if population struc- by the food plant. ture is being monitored. If transects or quadrats are Surveys for monitoring purposes should ideally chosen on the basis of habitat suitability then data be carried out every year. For EIA studies one needs can be used as an index of abundance. If transects to be aware of the intra- and inter-annual variations or quadrats are randomly selected over the whole in abundance. Hence, a survey undertaken in one site then an estimate can be made of numbers at year only may not be representative of the that site. For rare species, which are found only in Lepidoptera population of a site. For less threat- restricted areas, quadrats or transects will usually ened species a count every 3 years may be suffi- be placed in areas where the species are known to cient. In all cases, however, if an apparent absence occur; this will make the most efficient use of sur- is detected in one year, annual surveys should be vey time. carried out for at least two further seasons before As with timed searches (Section 17.2.1), the sur- the conclusion can be drawn in the third that the veyors will need to be experienced in the recogni- species is probably absent. The necessary field tion of larvae, eggs and food plants. Knowledge of equipment is summarised in Appendix 6. the timing of larval emergence will also be necessary. Data analysis and interpretation As long as methods are standardised between Field methods years, trends in count data can be analysed by The principles of quadrat and transect selection are using techniques such as regression (Part I, covered in Part I, Section 2.3.3. When monitoring Section 2.6.4). Other kinds of statistical analysis rare species, sample points will generally be may also be appropriate, provided that sampling selected by judgement to include areas of suitable is representative (see Section 2.6.4). If data are habitat for the species in question. Transect length collected on the abundance of the food plant and quadrat size will depend on the habitat being 332 17 BUTTERFLIES

surveyed and the colony size of the species being (BMS) methodology is described in Pollard (1977), monitored. and reviews can be found in Pollard et al. (1986) and The precise methodology will vary according to Pollard & Yates (1993). The methods developed are which species is being surveyed and monitored. In both species- and site-specific. general, however, you will walk transects or search The advantage of using standard methods across quadrats systematically looking for larvae, eggs or all sites is obvious: you can compare data not only pupae. Timing of surveys will depend upon the between years for the same site but between sites, ecology of the species concerned; see Emmet & and monitoring is made much simpler if everyone Heath 198( 9) for more information. uses similar methods. Methodology and transect length or quadrat size should be standardised for each site and species so Field methods that different surveyors can produce comparable BMS methodology data. Surveys should ideally be carried out every A series of counts are made along a fixed route at year. For less threatened species a count every 3 each site; recording should ideally be carried out years may be sufficient. The field equipment weekly from 1 April to 29 September. For each requirements are listed in Appendix 6. count the surveyor walks at a uniform pace along the transect and records all butterflies seen within Data analysis and interpretation 5 m on either side of the transect. Provided that sampling is representative, data can To ensure comparability of counts, certain be analysed statistically by using standard tests weather criteria must be met. Counts are not (Part I, Section 2.6.4). Other kinds of statistical ana- made when the temperature is below 13 8C; from lysis may also be appropriate (see Section 2.6.4). 13 8Cto178C counts are made only when there is Data from samples selected by judgement can 60% sunshine, and above 17 8C counts can be made only be treated as an index of abundance unless even in cloudy conditions. In northern and western the area of suitable habitat is known and is reason- upland sites, the minimum recording temperature ably homogeneous. Larval population estimates in 60% sunshine may be reduced to 11 8C. Counts can be made if such data are gathered (see Section are carried out between 10.15 and 15.45 hours BST. 17.2.1). Each transect is divided into sections that Interpretation of larval population estimates broadly coincide with distinct habitat types within should be made with reference to counts of adults the broader site. The equipment necessary for field (Section 17.2.3); many larvae will not survive to monitoring is listed in Appendix 6. reach adulthood, and the number of larvae will be greater than the number of adults that produced Data analysis and interpretation those larvae, as each female lays more than one Data from butterfly transects will generally be trea- egg. Larval numbers, therefore, are an index of ted as an index of population size. Provided that the adult population that produced that genera- sampling is representative, data can be analysed tion, and of the next generation of adults, but the statistically by using standard tests (Part I, Section numerical relation between these will vary depend- 2.6.4). Other kinds of statistical analysis may also ing upon the species in question and environmen- be appropriate (see Section 2.6.4). However, tal effects. although year-to-year changes on a site may be due to the effects of site management (Pollard, 17.2.3 Adult counts: transects 1982) they may also be related to national trends, which may be caused by weather patterns (Pollard Principles & Lakhani, 1985; Pollard, 1988) or other factors. A national scheme for recording butterfly numbers Caution is therefore required in the inter- by using standardised methods has been in opera- pretation of data; comparisons with other sites tion since 1976. The Butterfly Monitoring Scheme are invaluable. 17.3 Butterfly conservation evaluation criteria 333

17.3 BUTTERFLY CONSERVATION any part of Great Britain. This is implemented in EVALUATION CRITERIA UK legislation by being listed in Schedule 2 of the Conservation (Natural Habitats & c.) Regulations 17.3.1 Key evaluation considerations 1994. The Marsh Fritillary is the only butterfly listed in Compared with other invertebrate groups in the Annex II to the EU Habitats Directive of species of UK, butterflies receive considerable attention community interest whose conservation requires from the public and policy makers. The the designation of Special Areas of Conservation Butterflies for the New Millennium project, organ- (SACs). The Large Copper, also listed in Annex II ized by Butterfly Conservation and the BRC, has and IV of the Habitats Directive, is considered brought together data from a variety of sources to extinct in the UK. produce the Millennium Atlas of Butterflies in Britain Eleven species are currently priority BAP spe- and Ireland (Butterfly Conservation, 2001). This atlas cies, and a further 14 are BAP species of conserva- provides an assessment of the habitats and threats tion concern. facing butterflies, as well as changes in distribution since the previous atlas (Heath et al., 1984). Further sources of data that have been used in the 17.3.3 Conservation status in the UK production of atlases include the Butterfly Two resident butterfly species are classified as Monitoring Scheme run by the Centre for Ecology Endangered, three as Vulnerable and two as Rare and Hydrology at Monks Wood. This scheme moni- in the British Red Data Book 2: Insects. However, tors changes in butterfly numbers based on trans- the Red Data Book was published in 1987 and but- ects carried out throughout the summer at a series terfly populations and distributions have changed of set monitoring sites throughout the UK. However, since. For example, one of the endangered species, most rare species are not included in this. A less the Large Tortoiseshell, is now considered to be formal scheme is the Garden Butterflies Count extinct. organised by Butterfly Conservation on an annual Five of the resident species of butterfly have basis. This provides much wider coverage than the become extinct in the UK since the nineteenth Butterfly Monitoring Scheme, but is less reliably century, and over half have declined substantially standardised. in distribution. Habitat specialist species, i.e. those that use more localized habitats such as chalk 17.3.2 Protection status in the UK and EU grassland or ancient woodland, have tended to decline, whereas most wider countryside species Appendix II of the Bern Convention lists threehave spe- not suffered as much. However, some wider cies of butterfly that occur or occurred in Britain countryside species such as the Small Copper and have consequently been included in the Lycaena phlaeas and the Wall Brown have declined Wildlife & Countryside Act 1981: Large Blue severely, and there is evidence to suggest that Maculinea arion, Large Copper Lycaena dispar and although they are still widespread at the 10 km Marsh Fritillary. grid square level they have declined in abundance Twenty-five of the 59 species of British butterfly and distribution within those squares (Butterfly are listed in Schedule 5 of the Wildlife & Conservation, 2001). Countryside Act 1981, although only six receive Of the 11 priority BAP species, over the past two full protection as amended by the Countryside & decades seven have continued long-term declines Rights of Way Act 2000. The other 19 are protected (typically in excess of 30%), two have recovered from sale only. slightly, and one, the Large Blue, has been reintro- The Large Blue is the only butterfly listed in duced. Most of the species of conservation concern Annex IV(a) to the EU Habitats Directive, for species have also undergone substantial declines, with the in need of strict protection, whose range includes Wood White Leptidea sinapis in particular, by the 334 17 BUTTERFLIES

time of publication of the Millennium Atlas of eligible. All sites with endemic races of the Butterflies in Britain and Ireland, having disap- Grayling Hipparchia semele and Silver-studded Blue peared from 62% of the 10 km grid squares in Plebeius argus qualify. which it was recorded in 1970–82 (Butterfly For nationally scarce species, the three strongest Conservation, 2001). colonies within an AOS qualify, or five strongest colonies in an area that contains a substantial pro- 17.3.4 Site designation criteria portion of the British colonies. Within an AOS, sites with the two strongest colonies of a further 15 SSSI criteria for designating sites for butterfly inter- species that have experienced substantial local est are described in NCC (1989). In brief, the pre- declines can also qualify, although they should sence of colonies of Nationally Endangered, ideally also support colonies of some nationally Vulnerable or Rare species as classified by the Red rare or scarce species. An Area of Search is based Data Book are eligible, although only strong col- largely on counties in England, and largely on dist- onies of Vulnerable and Rare species may be ricts in Scotland and Wales. 18 * Moths

This chapter refers largely to the macromoths, the species in the defined area. A small number of although many of the techniques are also applicable colonies on one particular site does not necessarily to micromoths. Most macromoths are nocturnal, imply that a species is not at its optimal level, and this poses some problems for survey and moni- especially if the site is a part of the edge of the toring. For many species, light traps are the only main area for the species. reliable way of confirming the presence of adults. Colony numbers are relatively simple to estab- Adult moths are mostly highly mobile and rarely lish: presence of individuals can be used to imply site-specific, but larvae often live in discrete areas of the presence of a colony. However, failure to find suitable habitat. Such habitats may be large in the evidence of a species in one year alone cannot be case of grass-feeding species or very small and dis- taken as evidence of absence; several surveys with crete in the case of leaf miners. Separate popula- a negative result will be needed to confirm an tions may also exist within areas of suitable habitat. absence, particularly on sites where a species has Monitoring areas of suitable habitat may be previously been recorded. appropriate, particularly if resources are not available for more detailed survey methods. Monitoring 18.1.3 Population size of micro-habitats is not specifically covered in this Handbook. However, some of the techniques in Part II A more detailed assessment of moth populations may be adapted for this purpose. will entail estimates of population size. This can be achieved by counting adults (diurnal moths only), larvae or eggs along transects set up through areas 18.1 ATTRIBUTES FOR ASSESSING of suitable habitat. For species with discrete col- CONDITION onies, counting larvae on all the food plants in 18.1.1 Population range the area as part of a timed count may be better than transect counts. Transect recording methods Area of occupancy is an important attribute to may need to be tailored to suit particular species. monitor and can be best assessed by mapping Some species of nocturnal and diurnal adult male presence–absence. Repeat surveys will illustrate moths can be monitored by using pheromone traps expansions or contractions of range. or attracted to purposely bred virgin females. Over a period of years, annual numeric totals from light 18.1.2 Colony number traps will reveal population trends.

As mentioned above, adult moths are highly 18.1.4 Population structure mobile whereas larvae often live in discrete areas. The number of colonies may therefore apply more Some moths can be surveyed and monitored at the to larval populations than to adults. larval stage by counts on food plants. If the life The number of populations occurring in a site is history is known then counts of larval workings a straightforward indication of the overall health of can be made instead (especially for internal leaf

# RPS Group plc and Scottish Natural Heritage 2005. 336 18 MOTHS

feeders). Changes in the ratio of larval counts to high-pressure bulb is 60 m. Light traps catch the adult counts can be used as an indication of greatest number of moths on warm, still and overcast changes in population structure, which may be nights. If possible, you should try to use the traps caused by a number of factors such as increased during similar conditions on different nights. Never larval or adult mortality. use traps during heavy rain unless a rain shield is fixed to the trap, or the bulb may crack if water falls 18.2 GENERAL METHODS on it. However, trapping during light rain on a muggy summer evening can be extremely productive. General site survey methods for invertebrates are If the trapping location is not near a mains elec- provided in Chapter 10. tricity supply, batteries will be needed. Light traps The general methods for surveying and monitor- come in various designs and can be obtained from ing moths are outlined in Table 18.1. entomological supply merchants. It is also possible to construct them from scratch. In order to achieve 18.2.1 Light traps some degree of standardisation, operate the trap for the same length of time on each occasion. The Principles field equipment requirements for monitoring Most species of night-flying moth are attracted moths are listed in Appendix 6. towards light, particularly towards the ultraviolet There are a large number of macromoth species; (UV) end of the spectrum. They can then be caught some exhibit considerable phenotypic variation. in a trap for identification. Light traps can, in ideal Surveyors should therefore be experienced at iden- weather conditions, catch very large numbers of tification. Skinner (1998) is the standard work on moths. However, the numbers of moths caught is moth identification. For many rare species listed in strongly dependent upon the prevailing weather site citations, light trapping is the best – perhaps the conditions, and therefore traps cannot realistically only – option for recording a presence–absence. be used for monitoring moth populations unless they are used almost every night over a period of Data analysis and interpretation some years (Ausden, 1996). Light traps are there- The variability of light trap data, depending on the fore best used for obtaining presence–absence data. weather, makes quantitative or semi-quantitative analysis impracticable for monitoring purposes. Field methods For example, an increase in wind speed will reduce The simplest light trap consists of a light (high- the numbers caught by a considerable amount. pressure MB mercury vapour bulbs are best, as Lighttrapdatacan,however,beusedtoestablish they emit both UV-a and visible radiation between the presence of species, which is most useful in EIA 350 and 650 nm) (Fry & Waring, 1996) on a cable studies. Moth monitoring has been patchy in the hanging outside a building; moths can be caught past; in many areas there will be little information with nets as they circle the light. on the species present so it will be difficult to make Catches can be increased by using moth traps regional evaluations for a particular site. Light trap (Figure 18.1), which also have the advantage that data can therefore be useful when surveying sites they can be left overnight without an operator that have not been previously surveyed for moths, being present (although many species of and can also be used as an effective means of detect- Geometridae and many families of micromoths ing the presence of species of conservation interest. will settle on the outside of the trap and subsequently take to flight again at first light). 18.2.2 Pheromone traps Traps should be situated so that the light source is not heavily shaded by surrounding foliage, because Principles this reduces the area over which the light will be Pheromone traps use pheromones that have been visible.Theeffectiveradiusofa125WwhiteMB isolated from female moths, or synthesised in Only qualitative data obtained: results greatly affected by weather Cannot be used for some species Does not attract females Pheromones are very expensive Standardising search methods may be difficult Survey times restricted by appropriate weather conditions Only applicable to diurnal species numbers of moths adult males if left long enough areas can be searched method, which produces comparable results Expertise required Advantages Disadvantages Identification Can attract large Trap operation Identification Will attract all Trap operation Identification Entire colony Identification Usually reliable species attracted to light Location of trap influences species caught certain species; not all moth pheromones are available larvae or eggs may be missed Small, cryptic species may be under-recorded Reasonable Biased towards Low Will only attract Will vary according to weather conditions at time of survey Reasonable Inconspicuous batteries must be transported long distances Depends to some extent on species of pheromones and species being trapped access straightforward Good Good if transect Population size data Efficiency Precision Bias Presence–absence Low if traps and Presence–absence Depends on costs Index Estimate Methods for surveying and monitoring moths Recommended species group Night-flying moths Moths with available pheromones Most moths Index Diurnal moths Index Table 18.1. Light traps Pheromone traps Larval or egg counts Transects: adults

337 338 18 MOTHS

laboratories, and used to ‘bait’ traps, which will species chosen. See Ekkehard (1986) for details attract and catch adult males. They have some about breeding moths in captivity. advantages over light traps in that they are more attractive over a greater distance and will therefore Field methods catch more male moths, but only from downwind A pheromone trap operates in a similar manner to a and often from considerable distances. Attracted light trap (Figure 18.1); moths are attracted into a males may not therefore truly relate to the survey chamber, which contains cover for them to hide site, whereas light traps only attract individuals underneath and from which they cannot easily fly that are close by. Data will still vary according to out. The pheromones come in liquid form and can be weather conditions, but if the trap is left out for a poured onto cotton wool or other absorbent material. sufficiently long period of time, which encom- In order to counter the effects of weather on the passes a range of conditions, some amount of numbers of trapped moths, the traps should be left standardisation can be achieved. open for at least a week during the peak flight sea- There are a number of commercially available son of the target species. Over this period of time, it pheromones but they are not available for all should be possible to trap all the males in the sur- species. Some are not species-specific and so rounding downwind area. The range over which can be used to attract a range of species. A fuller pheromone traps are effective depends on the spe- description of the use of pheromone traps to cies concerned. For example, Emperor Moth Saturnia attract clearwing moths (Sesiidae) can be found pavonia males can be attracted over a distance of in de Freina & Witt (1997). A cheaper and equally 8 km, whereas Vapourer Moths Orgyia antiqua are effective method of attracting males is the use of apparently attracted over much shorter distances. purpose-bred virgin female moths, which are Pheromone traps retain male moths, which are placed in the traps instead of pheromones. thus removed from the population. Prolonged use These will select only the males of the particular of pheromone traps can seriously deplete the

Ultraviolet mercury vapour bulb covered in Pyrex bowl or similar cover to protect from rain To mains or generator

Perspex vanes to prevent moths from circling the Choke to regulate current bulb and encourage them to drop down Power cable Bulb and vanes fit into cone

Perspex cone or plywood truncated pyramid

Holding container made from Container filled with egg boxes old dustbin or similar container to provide shelter for captured moths

Figure 18.1. A light trap for trapping moths. Source: Ausden (1996). 18.3 Macromoth conservation evaluation criteria 339

males in a given population (indeed, they are used as a pest removal tool in Kentish orchards, for 18.2.4 Transects example). Appendix 6 outlines the field equipment Principles necessary for trapping moths. Adult diurnal moths can be monitored by using the methods of the BMS or, for regional variation. Data analysis and interpretation These are described in Section 17.2.3 and in Counts obtained by using pheromone traps will be Pearce et al. (1996). an estimate of the total number of adult males. The sex ratio of moths is extremely variable between Field methods species; counts of males should therefore be used See Section 17.2.3. as an index of total population size. Provided that sampling is representative, data Data analysis and interpretation can be analysed statistically by using standard tests See Section 17.2.3. (Part I,Section2.6.4). Other kinds of statistical analysis may also be appropriate (see Section 2.6.4). Comparisons will only be valid if fluctuations due 18.3 MACROMOTH CONSERVATION to weather have been accounted for by using traps EVALUATION CRITERIA for a sufficient length of time. Otherwise, the data 18.3.1 Key evaluation considerations will reflect differences in trapping caused by factors such as wind speed and temperature more than any There is currently no comprehensive national data- real changes in the abundance of target species. set that can be used to assess the distribution and conservation status of the 900 or so UK resident macromoths, although Butterfly Conservation 18.2.3 Larval or egg counts is planning a National Macromoth Recording Principles Scheme. Some moth eggs and larvae can be monitored by Atropos and Butterfly Conservation currently using the methods described for butterfly eggs and organise an annual Moth Night that includes pre- larvae: timed counts (Section 17.2.1) and quadrats selected ‘target species’: scarce species that may or transects (Section 17.2.2). The surveyor will need occur more widely. This has generated useful infor- to be experienced in the identification of moth mation, including new county records and new larvae, eggs and food plants; consult Young sites for scarce species. (1979), Bradley et al. (1973; 1979) or Emmet & There is a network of county recorders for moths, Heath 198( 9) for further details on the ecologywith countyof distributions of moth species also avail- moths. Surveys should be timed to coincide with able on some web pages, e.g. on those of the Suffolk peak numbers of larvae or eggs. Moth Group (www.suffolkmothgroup.org.uk). Such surveys are highly specific and results may not be as simple to interpret as light trap data. 18.3.2 Protection status in the UK and EU However, they can be very effective for some species, such as the Welsh Clearwing Aegeria scoliaeformis, There are no resident moth species listed in which can be surveyed by counting pupal cases pro- Appendixes II or III of the Bern Convention, truding from birch (Betula spp.) trees. although some, such as the Willow Herb Hawkmoth Proserpinus proserpina, are found as occa- Field methods sional migrants in the UK. See Sections 17.2.1 and 17.2.2. Eight species of British moth are listed in Schedule 5 of the Wildlife & Countryside Act 1981 Data analysis and interpretation and are strictly protected as amended by the See Sections 17.2.1 and 17.2.2. Countryside & Rights of Way Act 2000. 340 18 MOTHS

No UK resident moths are listed in Annex IV(a) of vulnerable and fifty-three as rare in the British the EU Habitats Directive, for species in need of Red Data Book 2: Insects. A further four micro- strict protection, and hence no moth species are moths are classified as endangered and seven as listed in Schedule 2 of the Conservation (Natural vulnerable. However, moth populations are likely Habitats & c.) Regulations 1994. to have changed since the Red Data Book was The Jersey Tiger Euplagia quadripunctaria is the published, and without a national dataset, estab- only moth species occurring in the UK that is listed lishing the current national status of these and in Annex II of the EU Habitats Directive of species other species is difficult. of community interest whose conservation requires the designation of Special Areas of Conservation (SACs). However, this species is con- 18.3.4 Site designation criteria sidered to be outside its native range in the UK, so SSSI criteria for designating sites for butterfly inter- does not require site protection. est are described in Guidelines for Selection of Fifty-three moth species are currently priority Biological SSSIs (NCC, 1989). Moths are treated in BAP species, and many more are species of conser- general terms, i.e. as for other invertebrate groups vation concern. except butterflies and dragonflies, which are sufficiently well known to have separate treatment 18.3.3 Conservation status in the UK within the guidelines. The site designation criteria Twenty-one resident macromoth species and sub- for moths are therefore included in Section 19.3 species are classified as endangered, twelve as (Other terrestrial invertebrates). 19 * Other terrestrial invertebrates

Insects and other arthropods account for 26 000 of Prys-Jones & Corbet (1991), Oggier et al. (1998), the 88 000 species of all groups recorded in Britain. Yarrow (1995), Stubbs (1972), Blackshaw (1994) This figure excludes the terrestrial component of and Usher (1990). the non-arthropod invertebrates such as molluscs Clearly, given the number of species and variety (Anon., 1995). These species take a huge variety of of life histories, invertebrate monitoring is a com- forms, occupying many trophic levels and having a plex and time-consuming process. For general variety of either broad or narrow habitat require- invertebrate monitoring, resource constraints ments (Strong et al., 1984). Species occupy tree and may not permit the use of some of the more shrub canopies, grass and herbaceous vegetation, detailed methods described here. It may be neces- and roam the surface and subterranean compo- sary simply to monitor invertebrates indirectly by nents of soil. Species that undergo metamorphosis assessing the extent of suitable habitat and con- often have life stages adapted to contrasting habi- firming presence–absence of particular (selected) tats or resources within a habitat. Different species species on an occasional basis. See Part II for details can reproduce at different times of the year and in on habitat monitoring methods. For species of con- one or more generations a year. There are also servation importance, however, more detailed temporal considerations important in the design monitoring may be necessary. of sampling protocols. The varied life histories of Monitoring is often carried out on a site-specific different species translates to varied activity basis; methods for the same group may vary accord- through the season. Different species can also be ing to the class and complexity of the habitat and active during the day, others are active nocturnally, conditions pertaining at different sites. Again, it is and some are crepuscular. The number of different not feasible to cover this aspect in detail. However, groups and species in this category is immense. It is a combination of one or more of the methods therefore not feasible to give specific methods for described could be adapted to establish site-based all groups. monitoring for species of interest in particular This chapter presents general methods for inver- situations. For further information consult New tebrate monitoring, which can be adapted to suit (1998). the requirements of most groups. However, given The monitoring of many invertebrate groups the above constraints, as well as the difficulty in requires specialist knowledge about their seasonal identifying many species, there will be many situa- and daily activity, broad efficiency in the habitat tions in which the only practical course of action (e.g. the host plant species of herbivores) and iden- will be to engage an appropriate specialist (who tification. Identification of invertebrates will also may sometimes be a local amateur entomologist) often require specialist taxonomic knowledge, par- either to design the procedure or to carry out the ticularly because there is a lack of published iden- monitoring work in person. For more information tification keys for a significant proportion of regarding the monitoring of specific groups see invertebrate taxa. Despite some species being dis- New (1998), Southwood (2000), Greenslade (1964), tinct and recognisable in the field by generalist Morris (1991), Okland (1996), Roberts (1996), ecologists, species of taxa for which published

# RPS Group plc and Scottish Natural Heritage 2005. 342 19 OTHER TERRESTRIAL INVERTEBRATES

keys are available will require identification by from occasional visitors. This is best achieved when using microscopy in the laboratory. This can be a the target species are known to be either sedentary lengthy process; voucher specimens of species or weakly dispersing species, and will invariably identified in this way and unidentified specimens imply a need for discussion with an appropriate of taxa with no available published keys will need expert. to be sent away for verification and identification by the recognised expert or recorder for that group. 19.1.2 Population size Specific methods that have been developed for particular species of conservation interest are not For species of conservation interest that require covered in detail; references for BAP Priority more detailed monitoring, estimates of population Species, where available, are given in Appendix 1. size may be required. This will entail more detailed sampling of the population, in terms of number of samples and the time over which they are col- 19.1 ATTRIBUTES FOR ASSESSING lected. The methods detailed below will provide CONDITION an index of population size rather than absolute 19.1.1 Population range estimates. Several of the general sampling methods are capable of providing measures of relative trap Surveying and monitoring for the majority of abundance. However, interpretation of trap to invertebrates will generally consist of establishing actual abundance is a species-specific problem, presence or absence at a particular site or part of a depending on the sampling efficiency of the site and setting this in context. Care should be method, usually related to the size, mobility and taken when a species is not found on one survey form of attachment of the species and the complex- at a site where it has previously been recorded; ity of the sampled substrate. Invertebrates are natural population fluctuations may be responsi- small and often numerous and widely dispersed; ble. It is not at all possible to regard a species as it is therefore unlikely that monitoring will be able definitely absent until many years of appropriate to achieve the level of precision necessary to make survey yielding a negative result have elapsed; this estimates of the total population for more than just is particularly the case with some saproxylic bee- a few selected species. tles, which may spend ten or more years as larvae feeding inside timber. On the other hand, when an entire assemblage of species associated with a 19.2 GENERAL METHODS single microhabitat declines or disappears, there 19.2.1 Purpose may be cause for more immediate concern. Knowledge is always required of the season of An initial assessment to judge whether a site is activity of the different stages in the life cycle of likely to require a more in depth evaluation for the target species. Repeat visits or continuous invertebrates may be required, if there is insuffi- sampling methods will certainly be required if sev- cient information on the invertebrate interest of eral species of different taxa are to be monitored. the site (see Section10 on general site survey). Such Although the fact that a species is not recorded on an assessment should be brief, but sufficient to one survey does not prove absence, it only takes one assess the likely presence of important terrestrial record to prove presence. However, captures of sin- invertebrate species. gle specimens of a species must be carefully considered in relation to the sampling method employed. 19.2.2 Method Occasional captures of species from remote habitats are expected in samples from pitfall and window A site appraisal should be carried out by walking traps. Confidence in sampling small numbers of spe- over it. Habitat features of invertebrate interest cimens will require discrimination of rare species should be largely visible at any time of year, but 19.2 General methods 343

important invertebrates themselves are more sweep-netting because of their rapid response to likely to be visible from May until September. disturbance. Within this time span, it should be noted that cer- Checking of roads on or in the vicinity of the site tain species will often only occur in a more readily can give information on larger invertebrates killed observable form over a much shorter time period, by cars, especially the larger beetles such as Stag which can be under a month. Beetles Lucanus cervus (Hawes, 2003) and chafers. The initial survey should ideally be carried out in Those species that are not readily identified on warm, sunny weather so that as many invertebrate site, either because of the requirement for a microspecies will be readily observable as possible. scope or because of the need to refer to keys, can be Guidelines for the Butterfly Monitoring Scheme caught by using a butterfly net or pooter as (see Section 17.2.3) suggest weather conditions appropriate. that will also be suitable for a wide range of invertebrates other than butterflies. In brief, assessment 19.2.3 Interpretation of results should not be made when the temperature is below 13 oC (11 oC for northern and western upland sites); If protected species have been recorded in the area, from 13 to 17 oC there must be a minimum of 60% then a more detailed survey of the site for those sunshine; above 17 oC, the weather can be cloudy species would be required regardless of the find- so long as it is not raining. The windspeed should ings of an initial survey. The presence of habitat not be above 5 on the Beaufort Scale. features suitable for a protected species identified While the surveyor is walking over the site, in the initial survey should necessitate a further habitat features of invertebrate interest should be survey for the protected species if the protected noted. These will include such features as dead species is known to occur locally, even if the spe- wood, bare ground, soil types, variety of vegetation cies has never been recorded from the site before heights, habitat mosaics, and presence of flowering (because the species may have recolonised the site plant species (particularly Umbelliferae and since previous surveys, especially if it exists as a Asteraceae). In addition, direct evidence of inverte- metapopulation), or if the site and the local area are brate species should be noted, particularly for not known to have been surveyed for the species many species of groups such as Orthoptera (pre- before. If the usual range of the species were sence will frequently be determined by sound known, then in theory it should be possible to rather than sight), Hymenoptera, and especially determine how close a site for evaluation should day-flying Lepidoptera. Many species of Diptera, be to a known protected species site in order to although typically active and potentially visible require checking for the protected species. during the day, are likely to be missed because of However, in most cases the likely range is not their rapid response to disturbance. Attention known, and furthermore, information on the pre- should be paid to the invertebrates present on flow- sence of small patches of suitable habitat between ers, dung and carrion and under loose objects, the site with the protected species and the site for which can reveal important species of Coleoptera evaluation that could act as ‘stepping stones’ is and other less obvious invertebrates. Careful unlikely to be available. searches of vegetation, along the lines of the meth- In cases where other species of conservation ods described below in Section 19.2.6, can particu- interest are concerned, observation of one or larly reveal further species of Coleoptera, more of these species on the initial survey should especially leaf beetles (Chrysomelidae), in addition require further, more detailed surveys to be carried to Hemiptera and molluscs. Ideally, this latter out (a species of conservation interest being species method can be used in conjunction with some considered of interest to the site, whether they are sweep-netting: the sweep-netting will reveal priority BAP species or Species of Conservation insects missed in the search, and the search will Concern). Because only a small proportion of the reveal invertebrates that are easily missed by invertebrate fauna of a site would be directly 344 19 OTHER TERRESTRIAL INVERTEBRATES

observed on an initial survey, the presence of even species, because ad hoc search data cannot be com- a single species of conservation interest during the pared with other data. This means that, although an initial survey suggests that other species of conser- idea of the extent of the species can be obtained vation interest are likely to be present. from presence–absence in suitable areas, you If the initial survey reveals a wealth of habitat cannot ascertain with any degree of precision features of invertebrate interest, and additionally a whether the population is increasing, stable or rich diversity of invertebrate species are observed, decreasing. If a more detailed survey of species of even if no species of conservation interest were interest is required, one of the other methods out- seen then the site merits further surveys. A site lined in Sections 191.92..2.7– should be considered. rich in suitable features and with a diversity The efficiency of this method will depend on the of even common invertebrate species is likely to surveyor’s knowledge of the site and of the species; possess features and characteristics suitable for if you have to spend time searching first of all for species of conservation interest to be present. areas of habitat, efficiency will be reduced. It is The general methods for surveying and monitor- thus preferable that ad hoc searches be carried out ing invertebrates are outlined in Table 19.1. by staff with experience of the site and of the habitat requirements of the species being monitored. 19.2.4 Searches of adult and larval feeding Invertebrates can also be indirectly monitored or resting sites by measuring the area of suitable habitat (and perhaps establishing presence–absence in a sample of Principles that area). Clearly, it is a major assumption that the Surveying and monitoring of invertebrates is often invertebrate species would be present, simply as a carried out in an informal or targeted way; the product of the habitat condition. There are com- diversity of invertebrates is considerable and the monly empty niches in nature in which the prevail- degree of niche specialisation means that a species ing environmental conditions exclude species of interest may occur only on a very localised scale, from apparently favourable habitat (Strong et al., or will occupy a very specialised micro-habitat. For 1984; Sparks et al., 1994; Dennis et al., 1995). sites notified for their invertebrate conservation Methods for surveying and monitoring habitat interest, the habitat requirements of these species, extent are covered in Part II of this Handbook. and the area in which they are found, will sometimes be known, and possibly marked. In this case, Field methods a straightforward and cheap survey method is sim- The surveyor should carefully search the micro- ply to search areas of suitable habitat for the target habitat of the target species. The method of searching species, and draw up a basic distribution map based will depend upon the species and habitat in question; on presence–absence of the species in areas that there is not much in the way of specific guidance that could potentially support it. There is a presump- can be given in a general methods book, and appro- tion in this situation that the species can be easily priate expert advice should always be sought before found and identified in the field. inexperienced staff begin work. Consult some of the This ad hoc method has the advantage of being recommended s ou atrc est hen de of tHhisand book fo r relatively quick and simple to carry out and being further information on the ecology of invertebrate directly targeted at species of conservation interest. groups and species. Time of season, time of day and If monitoring resources are limited, this method, prevailing weather conditions will be among although incapable of providing comparable quan- the many critical factors for a successful survey. The titative data, provides one of the most efficient timing of surveys should coincide with the time of methods for monitoring species with specialised maximum abundance of the target species(e.g. mat- niche requirements. ing flights or larval emergence). A disadvantage of the method is that it cannot If you are aiming to draw up a distribution map provide estimates of the population size of target of the target species, it may be desirable to divide Disadvant- ages Data not comparable Variations in surveyor effort difficult to standardise Data variability high in heterogeneous habitats Results reflect activity as well as numbers Straight- forward method of establishing presence. Most usual method in EIA Enables comparable data to be collected Results can be extrapolated over wider area Narrows down search area Results can be extrapolated over wider area Collects large number of invertebrates Expertise required Advantages Identifi- cation Knowledge of habitat requirements of species Identifi- cation Knowledge of habitat requirements of species Identifi- cation Knowledge of habitat requirements of species Identifi- cation Knowledge Bias Cryptic species often over-looked Mobile species may escape Effects of timing will bias results Cryptic species often over-looked Mobile species may escape Mobile species may escape Species not equally likely to Low if not all of area is searched or timing is not synchronised with period of activity of target life stage as above distinctive species: as above measure Difficult to Good if area to be searched is small Reasonable Reasonable: Reasonable Good for Good absence Population size data Efficiency Precision Presence– absence Index Presence– Presence– absence Index Estimate Presence– absence Index All Recom- mended species group All Ground- dwelling species Ground beetles and other Methods for surveying and monitoring other terrestrial invertebrates Searches of adult or larval feeding or resting sites Table 19.1. Timed searches Quadrat searches Pitfall traps

345 Disadvant- ages Cumbersome and expensive Requires transport of equipment and fuel, which is problematic in remote areas D-vac requires regular servicing Traps must be regularly checked Data analysis problematic with minimum effort Reasonably accurate and easily standardised methodology Simplest way of sampling flying insects Expertise requiredof habitat Advantages requirements of species Identifi- cation Knowledge of habitat requirements of species Operation of sampler Identifi- cation Knowledge of habitat requirements be caught Weather and habitat complexity affects activity and hence numbers trapped species and species firmly attached to vegetation are undersampled; other species may be oversampled by suction at edge of nozzle height of trap affects types of species caught Mobile Good Low to reasonable dependent on device Reasonable Reasonable Nature and Population size data Efficiency Precision Bias Presence– absence Index Estimate absence Index ) Recom- mended species group epigeal or surface- active invertebrates Invertebrates in low vegetation Flying insects Presence– cont. ( Table 19.1. Suction samplers Window traps

346 Requires transport of slates, which is problematic in remote areas Traps must be regularly checked Data analysis problematic Straight- forward method of assessing abundance Simple method for sampling flying insects Identifi- cation Knowledge of habitat requirements of species cation Knowledge of habitat requirements of species of species Trap construction dependent: dry conditions lead to undersam- pling, wet card can compensate for this Good Reasonable Weather- Reasonable Reasonable Trap aspect Identifi- absence Index Presence– absence Index Molluscs Presence– Flying insects, particularly Diptera Artificial refugia Malaise traps

347 348 19 OTHER TERRESTRIAL INVERTEBRATES

the habitat area up into a grid and search for pre- permanently marked grids can be compared to sence in each cell. The size of the grid cells will examine range expansions or contractions. depend upon the level of detail required (for example, you may be interested in presence–absence in 19.2.5 Timed searches 1 km squares or in 10 m squares). Steel pegs can be used to mark the location of the grids permanently Principles for annual or longer re-survey. These can be relo- In the previous section, ad hoc searching was con- cated with a metal detector. Setting up a grid is sidered as a cheap and relatively efficient way of covered in more detail in Section 15.2.2. determining the presence or absence of species. If the species is readily identifiable in the field, The method has its limitations, some of which you can simply record the number of sightings. If can be addressed by using timed counts. Timed this is not the case, specimens will have to be counts bring an element of standardisation, collected for later identification. Collecting equip- enabling semi-quantitative data to be collected, ment, such as pooters or aspirators and specimen which can be compared across years or sites. They tubes, will be required, with a suitable killing agent also enable larger sites to be surveyed on a more and, if appropriate, a suitable preservative. rigorous basis. If it is necessary to collect invertebrates as part Timed counts can also be useful when monitor- of the study, careful thought should be given to the ing species that require destructive sampling (e.g. number of individuals that are taken, particularly dead-wood invertebrates). A timed search method for species restricted to a small number of micro- for dead-wood species could involve a 30 minute habitats or a limited area of the site, or where the search of randomly selected 50 m Â 50 m plots in a site contains a large part of the local, regional or woodland; this would avoid the destruction of all national population; in such situations, this meth- the dead wood in one area. odology may perhaps be judged inappropriate. If In a timed count, an area is searched for a fixed you are simply concerned with presence–absence, time and all individuals of the target species are the removal of several specimens is not necessary. counted or collected. Counts can therefore be It may be necessary to take samples (e.g. litter or expressed as numbers found per unit time and, if soil) and search these in the laboratory. This will search methods are reasonably standard between apply in the case of species that cannot easily be surveyors, data can be compared. This method can seen in the field. You should therefore consider the produce indices of abundance and relative abun- destructiveness of the search method. If it requires dance. It cannot produce estimates of population considerable disturbance to the micro-habitat (for size: you can never be sure that all individuals in a example, searching for dead-wood invertebrates), given area will be found during the search (this is and that micro-habitat is not widespread or will extremely unlikely). take time to recover, you should consider only Timed searches can be based on simply search- searching a portion of the habitat, perhaps by ing a set area for a standard period of time, or they using timed or quadrat searches (Sections can19.2.2 be combined with further subsampling of the and 19.2.3) to minimise damage. The recom- area by plots, quadrats or transects (e.g. divide the mended field equipment is listed in Appendix 6. area up into squares, select a sample of these and search for a set time in each selected square).

Data analysis and interpretation Field methods Data from ad hoc searches can only be used to estab- Selection of the appropriate field method will lish presence–absence. If the habitat of the target involve the same considerations as in Section species is mapped, a grid can be overlaid and 19.2.1 and will depend upon the ecology of the a distribution map drawn up based on presence– target species. It is beyond the scope of this absence in each square. Repeat surveys within Handbook to consider detailed methods for every 19.2 General methods 349

group of invertebrates. The reader should consult clipped and sieved or searched in a standard way some of therecommended sourcesat the end of (Williamsonthe et al., 1977; Southwood, 2000). Handbook for further information. Quadrat searches are best suited to less mobile Searches should be informed (i.e. only search in species such as snails. Fast-moving invertebrates areas likely to harbour the target species) and if may be under-recorded if they leave the quadrat possible conducted with a standardised method- area before the search is complete. If the search is ology so that other surveyors can repeat the survey sufficiently thorough, you may be able to detect all and obtain comparable results. The length of individuals in a quadrat and thus derive population search will depend upon the time available and estimates. For species that are highly mobile or the area that must be covered, but as a general cryptic, counts should be treated as population rule, counts should be 30–120 minutes long. indices. Frequency of repeat surveying will depend upon available resources and on the length of the various stages of the life cycle of the target species. The Field methods necessary field equipment for timed searches is A standard frame quadrat of size 0.25 m2 is gener- outlined in Appendix6. ally used for sampling invertebrates. The selection of quadrat locations is covered in Part I, Section 2.3.3. If you are targeting a particular species, you Data analysis and interpretation should restrict quadrat locations to areas of habitat Data from timed counts can be expressed as num- suitable for that species, to maximise search bers found per unit time assuming the search efficiency. focuses on identifiable features on each occasion. The quadrat should be laid on the ground and the If the site has been subdivided into equally sized vegetation or leaf litter within carefully searched for sample units, data can be expressed as numbers a set time (ideally 2–5 minutes depending on the found per unit time per size of area searched proportions of bare soil and plant cover and the (assuming the habitat structure within each sub- complexity of the vegetation). A longer search time unit is of equivalent complexity). Regardless of should be allowed for cryptic species. the units chosen to express the data, counts can It may be necessary to search two or three trial be analysed statistically provided that methods are quadrats not used in the analysis before starting on standardised from year to year and appropriate the specified sample, as it is an inevitable fact that sampling has been used (see Part I, Section 2.6.4). finding efficiency increases with time as observers ‘get their eye in’. 19.2.6 Quadrat searches A minimum of five quadrats should be taken from each sample area. A pooter or aspirator and Principles collecting bottle with a suitable killing agent will Quadrat searches are used to delineate small areas be needed to collect invertebrates for later identifi- of ground vegetation for intensive searching. They cation if the species cannot be identified in the can be particularly useful for species that have field. Species that can be readily identified on site specialised habitat requirements and therefore should be placed in a container until the search are only found in a few small areas; in this case, is completed and then released back to the the area of search is already narrowed down quite searched area. considerably. The use of quadrats to define smaller Timing of counts will depend on the ecology plots for searching within these areas can improve of the target species. However, you should always efficiency and will produce comparable, quantita- aim to make counts during similar weather tive data. To further standardise methods, each conditions: invertebrate activity is strongly quadrat should be searched for a set length of weather-dependent. The field equipment required time, or vegetation within each quadrat can be for quadrat searches is listed in Appendix 6. 350 19 OTHER TERRESTRIAL INVERTEBRATES

the time when trapping occurs (Honek, 1988). Data analysis and interpretation Otherwise, variations in trapping data could reflect Data can either be expressed as numbers found per changes in environmental conditions rather than quadrat (and hence per square metre) or, if several in the abundance of species. If monitoring is tar- quadrats have been taken, presence–absence in geted towards a species with particular habitat each can be used to calculate frequency. If the latter requirements, the traps will necessarily be placed measurement is used, you should remember that in areas of similar habitat from year to year, so the quadrat size could affect estimates of frequency first consideration will be met in most cases. (Appendix 5). In general, estimates of density Trapping in standard weather conditions is more should only be made if you can be reasonably cer- difficult. One solution is to leave traps open for a tain that all individuals in the quadrats were found. reasonably long period of time (e.g. 1 month); This will not be the case with more mobile, cryptic unless the weather varies greatly from year to or subterranean species; counts for such species year, the average conditions over a 1 month period should be treated as population indices. should be similar enough to allow valid compari- Data from different years can, potentially, be sons to be made. analysed statistically by using standard tests (Part I, There are also variations in the capture rates of Section 2.6.4). Comparisons of counts for monitor- different species of ground beetle (Carabidae) ing should only be made between areas of similar depending on their mobility, visual acuity and habitat; habitat variables will affect counts and may climbing ability, such that the relative abundance obscure any underlying trends in abundance. As of species in pitfall traps does not reflect the true with all experimental work, a control should be relative abundance of the species (Halsall & established where possible. This may take the form Wratten, 1988). In addition, some species of ground of parallel monitoring of another common species beetle emit pheromones that attract other indivi- that can generally be guaranteed to be present so duals to the trap (Luff, 1986). Pitfall traps tend to that fluctuations in its population can be compared catch more invertebrates greater than 3 mm long statistically with fluctuations in the population of (Ausden, 1996), but this may be due more to the the target species. mesh size used to sieve samples after collection; a smaller mesh size will probably increase the num- 19.2.7 Pitfall traps ber of smaller invertebrates detected. You should therefore be wary of extrapolating relative abun- Principles dance from pitfall trap data to relative abundance A pitfall trap is a vertical-sided container that is dug of overall populations. Pitfall traps should mainly into the ground so that the top is level with or below be used for monitoring indices of population size. the ground surface; invertebrates walking along the It is possible to sample for long periods (continuous ground inadvertently fall into the trap. Pitfall trap- trapping through a season) to overcome these ping is probably the most widely used method for inter-species differences in ease of capture and sampling invertebrates, and is a cheap and straight- variations in season of activity, which affect the forward way of catching a large number of inverte- proportions in traps during short trapping periods brates with the minimum amount of effort. (Baars, 1979). As a monitoring method for comparing numbers caught over time, pitfall trapping has the Field methods disadvantage that invertebrate activity is greatly Any straight-sided container can be used as a pitfall affected by the surrounding vegetation and by trap (Figure 19.1). For example, large yogurt pots weather (Greenslade, 1964; Baars, 1979). When with snap-top lids are suitable and cheap. comparing counts from different years, you must Monopots with snap lids are cheap but can be used attempt to standardise the micro-habitat in which only once and often leak fluid; screw-top honey pots the traps are placed and the weather conditions at are more durable but the Environmental Change 19.2 General methods 351

Wire netting to prevent small mammals and amphibians from Top of trap flush falling into the trap with ground level

Drain holes to allow excess rainwater to escape. Drilled at two-thirds height of trap

Preservative/water filled to just below drain holes

Figure 19.1. An invertebrate pitfall trap. See text for details.

Network (ECN), a UK-wide monitoring scheme, uses To prevent captured invertebrates from eating standard pots 7.5 cm in diameter and 10 cm deep each other in the trap, the bottom should be filled from A. W. Gregory Ltd (Eyre et al., 1989). to just below the level of the drain holes with a The traps are dug into the ground so that the rim preservative. A standard preservative is 40% ethy- of the trap is flush with the ground surface. lene glycol (commercial antifreeze), 5% formalde- A circular piece of wire mesh or chicken wire hyde and 2% sodium chloride in water, with a should be wedged into the top of the trap to reduce detergent additive to reduce surface tension the chances of amphibians and small mammals (a small squirt of washing-up liquid). The use of from falling into the trap. The mesh size should formaldehyde is governed by the COSHH (Control be large enough to allow invertebrates to enter of Substances Hazardous to Health) regulations; it the trap but small enough to discourage larger is not absolutely essential to the mixture although species such as shrews. Alternatively, the ECN pro- it acts to prevent decomposition and thus reduces tocol uses a small rectangular sheet of chicken wire the attractiveness of the traps to carrion-feeding laid over the trap and surrounding ground, pinned species of invertebrate and to foxes, which may down with metal staples. otherwise dig the traps out. Salt helps to coagulate If traps are to be left open for any great length of slug mucus. time during wet conditions, a raised lid on legs can If the trap is to be emptied in situ more than once, be placed over the trap to prevent it from filling up it can be helpful to place the trap in a tight-fitting with rainwater, although not where grazing ani- plastic collar (e.g. a length of drainpipe) before dig- mals have access. However, it should be noted ging it in. The trap can be removed from the collar that lids over pitfall traps may reduce the number without causing the sides of the hole to fall in. An of spiders entering the traps, although it may alternative is to use two plastic vending machine increase the catch of ground beetles. Holes should cups, one inside the other. This also makes digging be drilled in the trap approximately two-thirds of in the trap easier: the inner cup can be removed and the way up from the base to allow excess rainwater soil that fell in during setting shaken out so that a to drain out and prevent the trap from flooding. clean trap is presented. If this design is used, it is 352 19 OTHER TERRESTRIAL INVERTEBRATES

important to drill drain holes in both cups, because Note that slugs and earthworms should be col- there is no soakaway for overflowing rainwater. lected in a separate container because the mucus The selection of locations for pitfall traps will associated with these species can foul up traps so depend on the size and nature of the area to be that other material cannot easily be separated. If sampled and upon the ecology of the target species. the traps are to be emptied more than once, the Traps are unsuitable in very stony, shallow or liquid can be reused, although it may require top- waterlogged soils. If a large area is to be surveyed, ping up. The ECN protocol suggests replacement it will be best to subdivide the area into equally with a new cup already containing preservative; sized squares and select a sample of these in the lid of the cup can simply be transferred from which to put traps. the new to the old pitfall cup. A total of ten (five at a squeeze) traps should be Filters are best floated invertebrate-side down- placed in a straight line, 2 m apart in each sample wards on a bowl of water and any invertebrates area. This makes the traps easier to find on subse- that remain attached removed with a wash bottle quent visits; they may often become hidden by (squeezy bottle filled with water) and an artist’s fallen leaves. You should always make notes of paint brush. Stones, leaves and other debris may trap locations; it is frustrating and time-consuming now be removed and the water in the bowl is then to have to search for traps on each subsequent visit. passed through a muslin or nappy liner filter held Vegetation growth over the traps can obscure the in a funnel. The pellet of invertebrates is stored in trap from view even when the location is found. an appropriate preservative for examination. Sometimes a garden fork can be gently pressed into Appendix 6 summarises the field equipment the vegetation systematically through the approxi- that will be needed for pitfall trapping. mate location; the chicken-wire cover is often detected in this way, even below a layer of annual Data analysis and interpretation vegetation growth. Pitfall trap data can be expressed as number of When traps are emptied, the liquid from the individuals found per trap: an average number traps (if it contains anything other than water) from all traps put down (Southwood, 2000). If the should not be allowed to run out on to, and hence site was subdivided or stratified, data can be pollute, the site; strain the liquid from the traps expressed as number per sample unit (total num- into an empty container and remove from the site. ber from all traps in one unit) and numbers from The liquid should be strained, because the move- sample units from areas with different habitats can ment resulting from transporting specimens in a be compared (Luff & Rushton, 1989). fluid (especially if mixed with small stones) will It is difficult to relate trap data to density unless cause damage. The trap contents should be poured you have an idea of the range over which indivi- on to a muslin cloth, nappy liner or similarly fine duals of the target species forage. It is thus not and soft filter. The mesh sizes of any series of filters practicable to estimate absolute abundance from used must be sufficiently small to retain inverte- pitfall trap data unless trapping periods are long brates as small as 1 mm in length. The pot should and samples are accumulated for the whole period then be rinsed and again emptied into the filter to (Baars, 1979). Data from several years can, poten- avoid the loss of very small specimens. Larger tially, be analysed statistically by using standard stones and other debris may then be picked out tests (Part I, Section 2.6.4). for disposal after first being washed by hand in a If using such data to identify trends, you must be jam-jar of water to ensure that no invertebrates are careful: numbers trapped can vary according to the attached. The wash water is then also passed weather or surrounding vegetation. A change in through the filter. The filter is then folded, speci- numbers over time could be due to changes in mens inwards, and placed in a plastic bag for trans- activity influenced by successional changes in the port to base. On returning to base it can be placed vegetation rather than an actual change in the directly in a preservative for later examination. number of individuals. Successional changes may 19.2 General methods 353

in themselves be affecting numbers in one particu- Field methods lar area, but the overall number may remain stable The most commonly used purpose-built sampler is unless the area of suitable habitat is itself decreas- the Dietrick sampler, or D-vac (Dietrick et al., 1959). ing. Most confidence in invertebrate data from var- This is a large and expensive piece of equipment, ied habitat complexity in space or time is achieved which is carried on the surveyor’s back. Smaller when catches are higher in the more complex and more lightweight samplers have been devel- vegetation, because you would expect reduced oped from suction machines originally designed mobility of invertebrates (Greenslade, 1964). for the removal of leaves and other garden litter. These generally have greater suction power than 19.2.8 Suction sampling D-vacs, owing to the smaller nozzle size, and are about a third of the purchase price. In addition, the Principles leaf blowers require less servicing than the D-vac Suction sampling is used to sample invertebrates (Macleod et al., 1994; Stewart & Wright, 1995) and from vegetation, leaf litter and the soil surface. It are therefore more efficient and produce more collects far more species from more invertebrate accurate results when used in conjunction with a taxa than does sweep netting (Southwood, 2000). metal ring quadrat, e.g. 0.25 m2 size (Macleod et al., Sweep netting collects from the vegetation and is 1994; Samu et al., 1997). dependent on the standing biomass of vegetation; There are two basic field methods for sampling a it is therefore too variable to be used as a monitor- patch of vegetation. If the collecting nozzle is large, ing tool, whereas suction sampling methods can be it is pushed vertically into the vegetation and held sufficiently standardised to produce comparable for a set length of time (30–60 seconds) to collect data. Invertebrates from a set area of vegetation invertebrates from an area the size of the nozzle. are sucked into a net by using a mechanical suction This should be repeated five times for each sample device (Dietrick, 1961; Macleod et al., 1994; Stewart (Dennis et al., 1998). Alternatively, a plot of a given & Wright, 1995; Samu et al., 1997). Comparisons size can be sampled for a set length of time. can be made between suction samples from differ- After sampling, the net containing the inverte- ent years provided the same size area is sampled. brates should be checked to remove newts, mice Suction sampling by D-vac (see below) is only and other things sometimes inadvertently collected, really effective in vegetation that is less than 15 cm then emptied into a plastic bag. A cotton-wool ball high and not flattened by wind, rain or trampling soaked in ethyl acetate should be introduced to the (Duffey, 1980;Ausden,1996). The use of modified bag before closing it. Note that ethyl acetate is a leaf blowers with a steel ring enclosure increases solvent and will dissolve polythene; it is worth efficiency significantly (Stewart & Wright, 1995; while experimenting with the container before col- Samu et al., 1997). Samplers also cannot be used in lecting to ensure that it will not be dissolved. The damp conditions. Large invertebrates that are quick bags should be stored in a freezer until they are to take shelter, or are firmly attached to the vegeta- taken to the laboratory for sorting and identification, will be undersampled. Some invertebrates may tion. It will be necessary to separate plant debris also be disturbed by the noise of the engine. from the sample; this is usually done by dry sieving For those invertebrates that are easily dislodged (Dennis et al., 1998). The field equipment necessary and sucked up (e.g. Hemiptera and linyphiid for suction sampling is listed in Appendix 6. spiders), you can assume that practically all the individuals in the sample area have been caught. In this case, you can derive total population esti- Data analysis and interpretation mates from suction sample data. For other inverte- Analysis will depend to some extent on the sample brates (e.g. Lycosidae, which are large hunting method; if a sampler with a large nozzle of stan- spiders), data should be treated as a population dard area was used, you can assume that all inver- index rather than as a total population estimate. tebrates immediately under the nozzle were 354 19 OTHER TERRESTRIAL INVERTEBRATES

sampled (some can be oversampled; see Samu et al., when the trap is set just above the level of the 1997) and you can therefore estimate invertebrate surrounding vegetation (Usher, 1990). density. By extrapolation, you can derive popula- It is also possible to bait traps (for example, with tion estimates if the area of similar habitat to that a sugar solution) to increase their attractiveness. sampled is known. Whether or not the trap is baited, you cannot be If a defined plot was sampled for a given length sure of the size of area from which insects are of time, data can be expressed as numbers found attracted, and therefore population estimates for per unit time or per plot area, but these can only a site cannot be made. be used as population indices, because you cannot The numbers of insects caught in traps will also be sure that all invertebrates were collected. vary according to their activity, which is affected by Data from different years can, potentially, be weather and the surrounding vegetation, as well as analysed statistically by using standard tests (Part I, reflecting variations in actual abundance. It is Section 2.6.4). therefore hard to standardise methods sufficiently to enable quantitative data to be collected; a semi- quantitative index of population size is the best 19.2.9 Window traps estimate obtainable from window traps for monitoring purposes. Principles Flying insects can be difficult to sample by using Field methods timed searches or other methods detailed in this Details of window trap construction are shown in section; they can be hard to catch and are rarely Figure 19.2. Traps consist of a platform mounted on easy to identify in flight. Window trapping is a way a wooden stake, which is driven into the ground. round this problem. Many species of flying insect The tray filled with water is placed on the platform are attracted to particular colours. A window trap and secured with string or elastic. combined with a perpendicular clear, perspex sheet both attracts and intercepts flying insects, capturing them in a water-filled coloured tray. Perspex sheets slotted together These traps can be used to sample flying insects in to deflect insects into bowl most habitats. The colour of the trap and the height of the trap Bowl filled with 2–3 cm water (add some drops of detergent above the surrounding vegetation will affect the to reduce surface tension) types of insect that are caught by attraction. Yellow traps are best for catching Diptera and Hymenoptera, whereas white ones attract Diptera but are less effi- Platform attached to stake cient for some species of Hymenoptera. Neutral col- with brackets and screws ours such as blue or grey can be used; these have the Bowl secured by least attractant or repellent effect and thus reduce elastic or string the sample selectivity (Usher, 1990;Disney,1986, 1987;Okland,1996). The height at which traps are set will depend Wooden stake driven into ground upon the aim of the survey. If you are establishing a baseline species list as a basis for future monitoring, a variety of different coloured traps should be set at a variety of heights. If traps are used for surveying and monitoring a particular species over time, identically coloured traps should be Figure 19.2. A window trap for flying insects. See text used at a constant height. Trap catches are highest for details. 19.2 General methods 355

Traps will need to be checked regularly, because the species under consideration. In a small site, the water will eventually evaporate and trapped presence in a trap does not prove presence on the insects will decay or be eaten. Alternatively, the site; individuals may have been attracted to the trap may fill up with rain and overflow if it is not trap from outside. For larger sites, presence in a regularly emptied. If rain is expected, drain holes trap will confirm presence, but absence cannot be should be drilled just below the top of the trap taken for granted until several years of data have sides. The trap can be filled with a non-evaporating been collected. If monitoring times are infrequent preservative, such as 40% ethylene glycol, 5% for- (i.e. every few years) it will be difficult to establish maldehyde and 2% sodium chloride in water, with a trends reliably. detergent additive to reduce surface tension, but Counts of insects from window traps can be trea- this will affect the attractiveness of the trap. Better ted as indices of abundance and can, potentially, results are obtained with plain water and a squirt of be analysed statistically by using standard tests washing-up liquid to reduce surface tension, so (Part I,Section2.6.4)ornon-parametricequivalents. avoiding a lingering death for the insects (tip: add Interpreting such data is again complicated by the the detergent to the filled trap; if you make up the fact that the area of influence of the trap is not mixture before leaving base you will have nothing certain, and in any case it will vary depending but bubbles to pour into the trap), but this requires upon the weather conditions at the time of the trap to be emptied at least every other day to sampling. avoid decomposition. Methods must be standard- Despite these drawbacks, window traps are a ised if results are to be used for monitoring. good method for monitoring flying insects that The decision as to where to place traps and at cannot always easily be sampled by using the what height will depend upon the species being more quantitative methods in this section. surveyed (Okland, 1996; McWilliam & Death, 1998). Where grazing stock, Rabbits or deer are present, 19.2.10 Malaise traps ground-level traps are not advised. The timing of trapping should coincide with the maximal abun- Principles dance of the species in their flighted phase. If this is A Malaise trap is a tent-like net, erected in the not known in advance, trapping should be continu- habitat to be sampled. Insects collide with the cen- ous, with frequent changeover of preservative, to tral net wall and are funnelled upwards to a catch- establish when peak numbers occur. However, num- ing chamber. This method almost always generates bers will be influenced by other factors such as huge volumes of material; several days are nor- weather, so identifying peaks of abundance will not mally required to sort and identify specimens be straightforward (the convention is to sample con- from a single trap session. They can be run all tinuously throughout the season (spring and sum- year without a break, though samples should be mer) for general invertebrate surveys). collected at least monthly. Malaise traps are an When traps are emptied, strain the liquid through incredibly effective method for sampling all flying a muslin cloth, nappy liner or other soft and fine insects and often record insects that have not been filter (see Section 19.2.7 on pitfall traps) and place found by any other method. An average Malaise the insects into a bottle or jar filled with a preserva- trap sample for the month of July in a varied habi- tive such as a 70% alcohol and 1% glycerol solution. tat in southern Britain could contain a hundred The contents should be sorted and identified in the thousand insects or more. laboratory. The equipment required for window trapping in the field is summarised in Appendix 6. Field methods Caution should be taken in the use and positioning Data analysis and interpretation of such traps, as the size and shape of Malaise traps Analysing window trap data can be problematic: will tend at best to arouse curiosity from the gen- you will not necessarily be certain of the range of eral public, and at worst they may be vandalised. 356 19 OTHER TERRESTRIAL INVERTEBRATES

The choice of habitat and aspect for setting up of or long-term studies Malaise trapping is, however, a Malaise trap will affect the species caught; simply the methodology most likely to reveal the true to survey for the maximum number of species on a extent of the on-site invertebrate biodiversity. site, positioning the trap on the boundary between habitat types or features of invertebrate interest is 19.2.11 Artificial refugia likely to produce the best results. Traps are usually left all year and the catching Principles chamber is charged with alcohol or another preser- Cardboard, slate, ceramic or wooden tiles can be vative so that it may be emptied infrequently: fort- used for monitoring slugs and snails. These species nightly in the summer or monthly when the will generally conceal themselves under objects on volume of insects caught is less. the ground during the day. If you lay down tiles to encourage slugs and snails to use them, they can be Data analysis and interpretation surveyed by simply turning the tiles over during Caution must be exercised in interpreting results the day and counting any species that are found. from Malaise traps. By definition, the traps work Density estimates can be made from such data if best when placed across flight-lines and as a conse- the slates are randomly distributed in similar habi- quence are very likely to catch insects that are tat (Williamson et al., 1977; Oggier et al., 1998). merely passing through the site rather than resident thereon. Large numbers over a lengthy period Field methods do not necessarily indicate residence as there may The tiles (10 cm Â 10 cm in size) should be placed have been a single large movement of individuals. out in a random pattern at an average density of A greater degree of reliability can be obtained from four per square metre in areas of habitat suitable shorter time period samples if unexpected species for the species of interest. Once a suitable period of are either not repeated on subsequent dates (indi- time has passed to allow for acclimatisation, the cating a passing species) or if they occur in all tiles should be turned over and any individuals samples (suggesting residency on site). Traps found under the slate can be identified and placed in dense cover in central areas of sites are counted. It may be necessary to collect specimens far more likely to record site-related species than for identification in the laboratory; in this case, traps situated in rides or across hedge lines. collecting jars will be needed with a suitable killing Counts of insects from Malaise traps can be agent and preservative. treated as indices of abundance and can, potentially, The best time for surveying and monitoring be analysed statistically by using standard tests slugs and snails is overnight after a rainy day, (Part I,Section2.6.4)ornon-parametricequivalents. hence tiles should be placed out on a wet evening Other kinds of statistical analysis may also be appro- and reviewed the following morning. Tiles should priate (see Part I, Section 2.6.4). Interpreting such be used to survey the habitat on at least three occa- data is again complicated by the fact that the area of sions each season to obtain an average (Oggier et al., influence of the trap is not certain, and in any case it 1998). The activity of slugs and snails is strongly will vary depending upon the weather conditions at influenced by the wetness of the weather; you the time of sampling. should therefore aim to collect data only during In spite of these drawbacks, Malaise trapping is periods of warm, wet weather. The gastropod spe- the single most effective method of sampling over- cies per site are effectively sampled when more all insect species diversity at any site. There is than 150 tiles are used in the sampling procedure. inevitably an implication for an inordinate amount A soil core method requires only 10 samples of time (and hence cost) in identifying the large of dimensions 25 cm Â 25 cm Â 10 cm to achieve samples. In smaller studies, target taxa can be the same degree of accuracy, but demands a time- sorted from the bulk samples to provide a realistic consuming extraction procedure in the laboratory snapshot of the invertebrate assemblage; in larger (Oggier et al., 1998). Appendix 6 outlines the 19.3 Conservation evaluation criteria 357

essential field equipment required for monitoring (Luff, 1998) and longhorn beetles (Twinn & Harding, by using artificial refugia. 1998). For a full list of available atlases, refer to the BRC website (www.brc.ac.uk). Data analysis and interpretation Invertebrate distributions can alter significantly Counts can be used to estimate density over the over a period of a few years, and caution should be area sampled with tiles. If the area of similar habi- taken with the interpretation of distribution and tat is known, this density can be extrapolated to rarity data, particularly if it is more than five years gain an estimate of the population in that area. old, as is frequently the case with published atlases. However, this is likely to be an underestimate, because it is doubtful that all individuals will 19.3.2 Protection status in the UK and EU be found under tiles; results should therefore be treated as an index of population size rather than Two species are listed in Appendix III of the Bern as an estimate of the total population. Convention: the Stag Beetle Lucanus cervus and Results from different years can, potentially, be Roman Snail Helix pomatia. The Roman Snail is an analysed statistically by using standard tests (Part I, ancient introduction to this country, and as such Section 2.6.4), particularly where the population is has not received protection in UK legislation. sampled appropriately. However, recent concerns about collection of this species for food have led to the proposal in the fourth quinquennial review of Schedules 5 and 8 of the 19.3 TERRESTRIAL INVERTEBRATE Wildlife & Countryside Act 1981 that this species CONSERVATION EVALUATION receive partial protection through legislation. CRITERIA Three terrestrial beetles, one hemipteran bug, 19.3.1 Key evaluation considerations three orthopterans, two spiders and one terrestrial mollusc species are listed in Schedule 5 of the ‘Terrestrial invertebrates’ covers a very wide range Wildlife & Countryside Act 1981 and are strictly of species, but the largest groups of concern are protected as amended by the Countryside & beetles, bees and wasps, probably because in this Rights of Way Act 2000. In addition, the Mire Pill country they are among the better studied of the Beetle Curimopsis nigrita receives only protection terrestrial invertebrates outside of the Lepidoptera. against damage to its place of shelter, and the In terms of information available to assess a site Stag Beetle is only protected against sale. for its invertebrate value, the Invertebrate Sites Two species of beetles, the Stag Beetle and Violet Register was set up in the late 1970s to bring Click-beetle Limoniscus violaceus, in addition to four together occurrence data on rare and scarce spe- whorl snails that occur in the UK, are listed in cies. The paper records of the Invertebrate Sites Annex II of the EU Habitats Directive of species of Register has been archived at Monks Wood BRC community interest whose conservation requires the since 1996, and its role is due to be taken over by designation of Special Areas of Conservation (SACs). the National Biodiversity Network, which aims to Of the terrestrial invertebrates, there are cur- link information held by local record centres and rently 73 beetles, 33 hymenopterans, 4 orthopterans, national recording schemes (Key et al., 2000). 22 flies, 5 molluscs, 6 spiders and 3 hemipterans that Invertebrate distribution atlases produced by the are priority BAP species. Around 40% of the species in BRC since 1997 have included land and freshwater the well-known invertebrate groups are Species of molluscs (Kerney, 1999), aculeate Hymenoptera Conservation Concern (Buglife, 2003). (Edwards, 1997, 1998; Edwards & Telfer, 2001, 2002), spiders (Harvey et al., 2002), Orthoptera (Haes 19.3.3 Conservation status in the UK &Harding,1997) and hoverflies (Ball & Morris, 2000). Provisional atlases have included Cantharoidea Around 500 invertebrate species are classified as and Buprestoidea (Alexander, 2003), ground beetles endangered, and over 1000 further species are 358 19 OTHER TERRESTRIAL INVERTEBRATES

classified as vulnerable and as rare in the British The criteria give room for the consideration of Red Data Books. species assemblages where it is possible to assess Since the British Red Data Books for insects and the quality of that assemblage. Methods for asses- other invertebrate groups were published, some of sing sites according to the assemblages present the species in them have become extinct. Others have been developed for saproxylic beetles (the have become much more widespread, e.g. the Bee Saproxylic Quality Index) and are under develop- Wolf Philanthus triangulum (Key et al., 2000) and for ment for the beetle fauna of exposed riverine other species there are probably insufficient data sediments. to assess their changing status. Criteria for designation of Ramsar sites also cover invertebrates. The most relevant criteria are criteria 19.3.4 Site designation criteria 2 and 3. Criterion 2 guidelines urge contracting parties to include in the Ramsar list wetlands that SSSI criteria for designating sites for invertebrate include threatened communities, or wetlands that interest are described in NCC (1989). are critical to the survival of species identified as The criteria laid out for designating SSSIs are vulnerable, endangered or critically endangered currently rather sketchy. The most definite of the within national endangered species programmes criteria is that all sites with populations of species or international endangered species frameworks, on Schedule 5 of the Wildlife & Countryside Act such as the IUCN Red Lists. Criterion 3 guidelines 1981 qualify for consideration. Other criteria are cover species considered internationally important that any site supporting the strongest population for maintaining the biological diversity of a particu- in the UK of a Red Data Book species should be lar biogeographic region. Characteristics sought considered, as should sites within an Area of under this criterion are ‘hotspots’ of biological Search supporting strong populations of Red Data diversity, centres of endemism, the range of bio- Book species in the better recorded groups. logical diversity occurring in a region, a significant Nationally Scarce species should be included in proportion of species adapted to special environ- the SSSIs within each Area of Search where they mental conditions, and wetlands that support rare occur, and all regionally scarce species within or characteristic elements of biological diversity of Areas of Search where they have this status. the biogeographic region. 20 * Aquatic invertebrates

A considerable range of techniques are available gain access to a water body, water depth and sub- for sampling aquatic invertebrates, a comprehen- strate stability should be checked (with a net pole sive description of which is beyond the scope of or similar) to make sure that it is safe to sample. this Handbook. Section 20.2 summarises the most Other safety aspects listed in Part I, Box 2.11, widely used methods, but variants have evolved for should be followed as appropriate. most of the techniques and equipment described. Surveying areas of suitable habitat may be A detailed account of sampling methods is given in appropriate, particularly if resources are not avail- Hellawell (1978, 1986) and Southwood (2000). able for more detailed survey methods. Surveying A summary can also be found in Ausden (1996) of micro-habitats is not specifically covered in this and RSPB/NRA/RSNC (1994). Handbook. However, some of the techniques in The timing of any survey of aquatic inverte- Part II may be adapted for this purpose. brates is very important. Some species may not be detectable at certain times of the year (e.g. when they have emerged as flighted adults, are present as 20.1 ATTRIBUTES FOR ASSESSING eggs attached to vegetation, or as very small instar CONDITION stages). For this reason, fluctuations in community 20.1.1 Community composition structure occur throughout the year and for comprehensive surveys it is therefore necessary to sam- The aquatic invertebrate community is composed ple in various seasons to maximise the number of of numerous organisms with a range of attributes species captured. The protocol developed and effort and habitat requirements. Therefore, when survey- expended will vary according to the objectives. ing the aquatic invertebrate community in general There are also particular safety aspects to con- (rather than when concentrating upon a particular sider when working in or near water. In particular, species of interest) it is often common practice to personnel should be trained in the relevant aspects condense complex community inter-relationships of aquatic safety and use appropriate safety equip- into a single index of species diversity. A good ment. Surveyors should be aware of the risk of review can be found in Metcalfe-Smith (1994). The catching Weil’s disease from water contaminated diversity index accommodates species data; how- with rat urine. Surveyors should work in pairs and ever, within the water industry, macroinverte- carry mobile phones or radios if working in remote brates have been traditionally sampled for water areas. These should be used to contact colleagues at quality assessment, for which it was considered agreed times to confirm that sampling is proceed- adequate to identify to family level only. Thus, ing safely and according to schedule. Boots or biotic scores are often based on family-level identi- waders are a necessity but chest waders should be fication (rather than on species-level), which is avoided, as they can seriously hinder mobility if obviously easier and cheaper to do. However, fuller they fill with water. Sampling should not be carried surveys with identification to species will be out when a river is in spate or when weather con- required to survey or monitor populations of spe- ditions are particularly bad. Before attempting to cies of conservation interest and to search for

# RPS Group plc and Scottish Natural Heritage 2005. 360 20 AQUATIC INVERTEBRATES

species new to the site that may require more detailed monitoring. Invertebrate sampling meth- 20.2.1 Vegetation sampling ods are fairly indiscriminate, in that they will cap- Principles ture members of more than one invertebrate group Many species of aquatic invertebrate can be found (although different methods will yield different on or among submerged aquatic vegetation. If you results). Therefore, unless you are concerned only sample this vegetation for invertebrates an idea with a particular species, community composition can be obtained of the species present, their abun- can be examined. A reduction in the diversity scores dance per unit of habitat or sampling time, and recorded at a particular site can be used as a trigger their overall relative abundance. to start more detailed monitoring programmes and In general, this method is best used for deter- also to provide an index of habitat quality. mining presence–absence of species. Population density estimates are problematic: since determin- 20.1.2 Presence–absence ing the density of aquatic plants being sampled is not always straightforward. Comparisons between Species of particular interest will need to be sur- sites are influenced by factors such as vegetation veyed in more detail than can be obtained from a type and density, which would have to be standar- community diversity index. It may be sufficient dised before meaningful quantitative comparisons merely to establish whether or not a species is could be made. present at a site or subdivision of a site, and thus An alternative method is to search the vegeta- map the distribution of the species. In this case, tion in situ for a fixed period. This enables compar- surveys will be targeted towards one particular isons between samples to be made on the basis of species, but general sampling methods will often numbers per unit effort and has the advantage of be similar to those used for community sampling. being less destructive. Monitoring for presence–absence can therefore be directed towards range expansion or contrac- Field methods tion of species of interest. In most EIA studies, for A sample of aquatic vegetation is collected in a net example, presence–absence is all that can be col- or other receptacle and taken back to the labora- lected within a given time-frame and these data are tory, where it is searched for invertebrates. then used to assess the number of species of parti- If sampling in flowing water, position the net cular conservation importance; less emphasis is downstream of the patch of vegetation to be placed on determining abundance. sampled and cut or pull out the vegetation so that it is carried into the net. This will help to ensure 20.1.3 Population size that invertebrates that are disturbed by the cutting of the vegetation are also directed into the net by For particularly rare or otherwise important spe- the current flow. When sampling in still water it is cies, it may be desirable to obtain an estimate of probably best to cut and enclose the vegetation as population size so that population fluctuations can quickly as possible to minimise the number of fast- be monitored and downward trends identified moving invertebrates that escape. before falling numbers lead to local extinctions. This method is best suited to vegetation in shal- Populations of aquatic invertebrates are gener- low waters and near banks; deeper waters will ally expressed in terms of density (individuals per cause problems with sampling because it will take square metre or individuals per sample unit). time to pull the vegetation to the surface, which will allow more invertebrates to escape or become dislodged. 20.2 GENERAL METHODS When searching vegetation in the laboratory, Table 20.1 outlines the general methods used for the best results are obtained by placing the plants surveying and monitoring aquatic invertebrates. in a shallow white tray and removing invertebrates Table 20.1. Methods for surveying and monitoring aquatic invertebrates

Recommended Population Other Expertise species group size data attributes Efficiency Precision Bias required Advantages Disadvantages

Vegetation Species on Presence– Vegetation Requires time Varies with Biased in Identification Samples can Destructive sampling submerged absence community to search density of favour of be searched Comparisons vegetation Index composition through vegetation sedentary thoroughly difficult between Biotic vegetation in spp. in laboratory different scores a laboratory vegetation types Sweep Species in the Presence– Water column Reasonable Varies with Highly Identification Quick and Difficult to netting water column absence and vegetation density of mobile simple field standardise and on Index community vegetation organisms methods effort between submerged composition may be under- surveyors vegetation Biotic scoresa recorded Kick Species amongst Presence– Benthic Reasonable Reasonable Biased against Identification Quick and Difficult to sampling sand, gravels absence community firmly attached simple field standardise and pebbles in Index composition and hea vy a spp. methods effort between flowing water Biotic scoresa surveyors Cylinder Species among Abundance Benthic Requires time to Good Low Identification Enables Requires sampling sand and gravel community set up equipment Equipment density expensive in flowing composition May be costly set-up and estimates to equipment water Biotic scoreas operation be made Artificial Bottom-dwelling Abundance Benthic Time needed Good May not sample Identification Removes Takes time substrates species community between putting slow colonisers substrate before samples composition down substrate variability are ready Biotic scoresa and colonisation

a When combined with samples of other community components. 361 362 20 AQUATIC INVERTEBRATES

as they are found. The greatest variety of inverte- possible. For further information on the subject brates will be found if the plant material is left see RSPB/NRA/RSNC (1994) for a useful summary; overnight in a water-filled, covered bucket. The Metcalfe-Smith (1994), Hellawell (1986, 1997 ) and oxygen depletion and reduction of water quality Wright et al. (1994) for reviews; and Hellawell will encourage invertebrates to come to the sur- (1978) and HMSO (1978, 1980, 1983) for methodo- face, where they can be more easily seen. The logical techniques. An account of the RIVPACS equipment required for vegetation sampling is approach, including some examples of RIVPACS II summarised in Appendix 6. predictions, is provided by Wright et al. (1997). Analysis of data for species monitoring is gener- Data analysis and interpretation ally more complex. Relative abundance can be In general, invertebrate samples can be processed compared over time to examine changes in com- similarly, irrespective of the method used to collect munity structure, but effective comparisons can them. This section therefore can be used when only be made if sampling effort is kept constant. considering qualitative and semi-quantitative ana- Comparisons of presence–absence data allow lysis for all the sampling methods described in this expansions or constrictions in the ranges of target chapter. Quantitative population estimates are species to be evaluated. This is best achieved by generally derived from data collected from solid looking at the frequency with which a species substrata: see Section 20.2.4. For further informa- occurs within a series of samples collected at a tion consult the references listed at the end of the range of points over a fixed period (i.e. presence– book. absence in each sample converted to percen- Invertebrates should be sorted, identified to the tage frequency: a species present in 2 out of 10 required level and counted. If the data are to be samples has a percentage frequency of 20%). used for biotic scores, identification is usually Changes in frequency over time can be analysed only necessary to family level. More detailed stu- with a 2 test. dies will require identification to species level, There is also a range of more complex multi- which requires a greater level of expertise. variate analyses, which can be used to look at A key use of invertebrate community data is to changes in community structure. Computer pro- calculate biotic scores as an indicator of water qual- grams are available, such as TWINSPAN, which ity. A recent development of the method by the uses classification techniques, and DECORANA, Environment Agency has been to compare actual which uses DEtrended CORrespondence ANAlysis invertebrate biotic indices with those predicted by (DCA) to condense variance within data into com- RIVPACS (River Invertebrate Prediction and ponent axes, which can be plotted, allowing you to Classification System) to produce a biological identify groups of roughly similar communities. General Quality Assessment (GQA). RIVPACS uses Comparisons of plots from different years will the environmental characteristics of a site to pre- enable you to identify shifts in community compo- dict the invertebrate community to be expected in sition. Alternatively, several years’ data can be the absence of environmental stress. The standard plotted together; if the different years are sepa- nationally used biotic index is the Biological rated, this can be taken as evidence that the com- Monitoring Working Party (BMWP) score system munity is changing. Multivariate analyses such as (National Water Council, 1981). Scores are based DCA should be used to identify possible changes, on the total number of families present, each which should then be examined by using more weighted according to its sensitivity to water qual- rigorous analysis. The use of multivariate analysis ity. Comparison between different years can be is commonly applied to vegetation data but can be made, although it should be remembered that bio- equally well applied to other organisms. For more tic scores are effort-dependent (i.e. the longer the information on these and other multivariate tech- search, the higher the score); the survey effort niques see Kent & Coker (1992), Manly (1986), should therefore be standardised as much as Cushing et al.( 198 0) and Omerod & Edwards1987). ( 20.2 General methods 363

20.2.2 Sweep netting 20.2.3 Kick sampling Principles Principles Sweep netting can be used to sample invertebrates Kick sampling is the most commonly used method that colonise submerged aquatic vascular plants, for obtaining qualitative data in flowing waters of algae and the submerged surfaces of emergent wadeable depth (Furse et al., 1981). If kicking effort vegetation. The principles are similar to those is kept constant, it is possible to obtain comparable applying to sweep netting for terrestrial inverte- samples from which estimates of relative abun- brates: the net is passed for a set distance dance can be derived. It has also been shown that through the vegetation for a set number of times. when a known area is systematically sampled, it Comparisons between surveys can be made as long is possible to derive approximate population density as sampling effort is kept constant. estimates (e.g. animals per unit area) (Armitage et al., The method is best suited to still or slow-flowing 1974). In general, however, kick sampling is used for waters; there is a risk that invertebrates will not be generating qualitative and semi-quantitative data. caught in the net in fast-flowing waters. Field methods The majority of invertebrates in flowing water are Field methods found among stones, gravel and silt on the stream This method is applicable to vegetation in waters or river bed. Kick sampling disturbs the substrate that are shallow enough to be waded or vegeta- and catches the dislodged invertebrates in a net tion accessible from banks. The net should be placed immediately downstream. swept with alternate forehand and backhand Kick nets are flat bottomed so they can rest strokes. Try to sweep the same distance from firmly on the substrate with no gaps under which side to side and to sweep for the same number invertebrates could escape. The net is placed on the of strokes for each different sample. The greater substrate, and the sediment in front and upstream the number of sweeps, the greater the number of of the net entrance is kicked a set number of times. species that will be caught; standardisation is The current carries the invertebrates into the net. therefore essential if comparisons are to be The sample is then transferred to a collecting bottle made. for sorting and identification in the laboratory If you are searching for a particular species (Section 20.2.1). rather than carrying out a general survey it may A further adaptation of the kick-sampling be possible, if the species is conspicuous, to pick method is the Surber-type sampler, which deline- out individuals from the net immediately. If the ates (by means of a square frame that rests flat on water is cloudy or full of debris, it will be preferable the stream or river bed) an area of substrate to be to sort through the samples in the laboratory. In disturbed. This gives a more quantitative sample this case, transfer the contents of the net into a area measurement, although numbers may be collecting bottle. influenced by the vigour with which the enclosed Refer to Section 20.2.1 for further information area is disturbed. In consequence, the Surber-type on the sorting of samples in the laboratory. sampler may indicate numbers of organisms in a Appendix 6 summarises the field equipment sample rather than the number per unit area of requirements for sweep netting. substratum. However, provided the substratum is disturbed systematically and thoroughly it is possi- Data analysis and interpretation ble to derive quantitative data. Surber-type sam- In general, sweep netting will yield qualitative or plers are best suited to slow-flowing water; there semi-quantitative data. For details on the analysis is a problem with specimen loss around the sides in of this type of data, see Section 20.2.1. fast-flowing water. 364 20 AQUATIC INVERTEBRATES

The recommended field equipment for kick A more sophisticated design, the airlift sampler, sampling is listed in Appendix 6. comprises a vertical tube, which is submerged in the water with its base pushed into the substrate. Data analysis and interpretation Compressed air from portable tanks is pumped For information on analysing qualitative and semi- into the lower end of the tube, causing it to vibrate quantitative aquatic invertebrate data, see Section and dislodge gravel and other benthic material. 20.2.1. The mixture of air, water and sediment is pushed up the pipe and into a bag net at the surface. This sampler is not recommended for use on mud. For 20.2.4 Cylinder sampling further information on airlift sampling techniques see Drake & Elliot (1983). The field equipment Principles required for cylinder sampling is listed in Cylinder sampling provides a method for obtaining Appendix 6. quantitative data on aquatic invertebrate populations. The method was designed to overcome the problem of sample loss around the edges of kick Data analysis and interpretation samplers or Surber-type samplers in deep or fast- Qualitative and quantitative data can be obtained flowing water. Cylinder samplers are particularly with cylinder samplers as outlined in Section suitable for sandy substrata and enable animals 20.2.1. Population density estimates (and therefore that may burrow at depths of up to 30 cm to be population size estimates) can be made with sam- captured. plers that quantify the area or volume being An area of substrate of known size is sampled by sampled. Population density (numbers per pushing the cylinder a small distance into the sub- unit area) can be multiplied by total area of substrate; in principle, this will collect all the inverte- strate to give an absolute population estimate. brates present, thus enabling population densities These values can be compared over time by using to be calculated. Cylinder samplers are available multivariate analysis for community data (see in a wide variety of designs, some of which are Section 20.2.1) or by using standard tests (Part I, described in Southwood (2000). Section 2.6.4).

Field methods 20.2.5 Artificial substrates The exact method for sampling with cylinders will depend to some extent on the type of cylinder Principles being used. The simplest and cheapest cylinder One of the most precise methods of sampling samplers are merely open-ended metal cylinders benthic invertebrates is to place a bag, tray or (usually stainless steel), often with teeth on the box on the bed of the river or lake and either bottom edge to ease their insertion into the sub- replace the substrate or allow sediment to accumu- strate.Thereisaholenearthebaseofthecylinder late naturally and invertebrates to colonise to which a bag-like net is attached, opposite Southwood, (2000). The box is then removed and which is an oval aperture covered by a metal the sediment searched for invertebrates in the grille. The sampler is pushed into the substrate laboratory. One problem with this method is that with the net downstream of the grille so that the population of invertebrates found on artificial water flows through the grille into the cylinder substrates may be different from that found on and out through the net. In this way, a known area natural ones; however, placing the same artificial of substrate is completely enclosed and can be dis- substrate in different areas gives a degree of stan- turbed to dislodge invertebrates, which then collect dardisation and hence enables data from different in the net. sites to be compared. 20.4 Conservation evaluation criteria 365

Because the area of artificial substrate is known, are constant, quantitative estimates of abundance quantitative density estimates can be made. If the can be made (Section 20.2.4). sample unit can be taken to the surface without any sediment being lost, the estimates will be 20.3 REQUIREMENTS FOR SPECIES OF reliable. PARTICULAR CONSERVATION IMPORTANCE Field methods The type of artificial substrate to be used must first 20.3.1 Freshwater Pearl Mussel be determined. These can range from simple trays Margaritifera margaritifera or baskets to the more complicated Ford box (Ford, The Freshwater Pearl Mussel is protected under 1962), which has two fixed sides and a bottom and Schedule 5 of the Wildlife & Countryside Act 1981 is placed in a hole on the water-body bed (with the and Annex IIa of the EU Habitats Directive. The UK sides parallel to the direction of stream flow if used is one of the last remaining strongholds for this in flowing water). After a given time (Ford left his species in Western Europe. boxes for 6 weeks), the other two sides are slid into A monitoring strategy has been developed by position, and the box is lifted out with the sample Young (1995). It should be noted that this survey undisturbed. procedure requires the surveyor to be licensed, The number of boxes used and the length of because it involves the disturbing of mussels. time they are left will depend upon the time and Surveyors will also need to be familiar with pre- resourcesavailableforthestudyandshould ferred substrate types (coarse sand set among cob- also reflect the aim of the study; the number and bles or boulders but sometimes solely coarse sand). distribution of samples should be calculated to Surveys should be concentrated in the most favour- enable statistically robust conclusions to be able substrate types in order to maximise search made (Part I,Section2.6). It is important that efficiency. time is kept constant to enable comparisons to Searches should be made with a glass-bottomed be made. viewing bucket during favourable conditions in For rocky areas of substrate, blocks or plates of shallow water. If no mussels are found after 2 regular size can be left and then turned over and hours a negative result can be reported. If mussels searched at a later date. Again, time and search are found, then a more systematic search is made, effort must be kept constant. along a 50 m Â 1 m transect from the point where Once the sample has been collected the inverte- the first mussel is found. All mussels are then brates must be separated from other benthic counted within this transect. Two 1 m2 quadrats material and counted. If the sample is large or should also be selected and carefully searched for contains a large number of animals, which are juvenile mussels. evenly distributed throughout the sample, subsamples can be taken. Hand sorting is the most widely used method for examining samples; 20.4 AQUATIC INVERTEBRATE see Section 20.2.1 for further details. The equip- CONSERVATION EVALUATION ment needed for monitoring aquatic invertebrates CRITERIA by using artificial substrates is summarised in Appendix 6. There are specific characteristics of aquatic invertebrates that must be taken into consideration Data analysis and interpretation when evaluating the importance of aquatic habi- Data obtained by using artificial substrates can be tats for conservation. analysed with qualitative or semi-quantitative First, the collection of aquatic invertebrates methods (Section 20.2.1). If sample area and time requires specialised techniques and, as many 366 20 AQUATIC INVERTEBRATES

species are cryptic, once they are captured their Criterion 2: A wetland should be considered identification requires significant experience or internationally important if it supports vulnerable, specialist keys. Consequently, information about endangered, or critically endangered species or the abundance and distribution of aquatic inverte- threatened ecological communities. brates is less complete than for other taxa in Criterion 3: A wetland should be considered the UK. internationally important if it supports popula- Second, very few aquatic invertebrates are tions of plant and/or animal species important for either listed on international conservation treaties maintaining the biological diversity of a particular (e.g. the Bern Convention) or protected under EU biogeographic region. and UK legislation, and so these instruments pro- Criterion 4: A wetland should be considered vide a limited basis for determining the conserva- internationally important if it supports plant and/ tion status of most species. Assessments of species or animal species at a critical stage in their life rarity are, therefore, reliant on other sources such cycles, or provides refuge during adverse as Red Data Books. conditions. Third, the composition of macro-invertebrate Wildlife & Countryside Act communities is closely linked to the physical and Section 9 of the Wildlife & Countryside Act chemical status of aquatic habitats. This is because 1981 (as amended) provides protection for those taxa respond differently to environmental stres- aquatic invertebrates listed on Schedule 5. Some, sors such as pollution, reduced flow and intro- such as Lesser Silver Water Beetle Hydrochara cara- duced species. Heavily modified, more uniform boides, receive full protection, others are protected habitats tend to support fewer species than do to a lesser degree. White-clawed Crayfish, for naturally diverse ponds, rivers and streams. example, is protected only from taking (capture) Aquatic invertebrate conservation has, therefore, and sale. tended to emphasise the importance of species For those species at most threat the British Red assemblages as much as the occurrence of specific Data Books (RDB) provide the most widely accepted species. categorisation of rarity (see, for example, Shirt, Bern Convention 1987; Bratton, 1991). There are three relevant RDB Signatories to the Bern Convention have agreed categories that can be used for this purpose. to protect invertebrate species listed in Appendix II * Endangered (RDB Category 1): species in danger of and III. Four of these are extant, native species that, extinction because numbers have declined to cri- for at least part of their lifecycle, depend on aquatic tical levels or habitats have been dramatically habitats within the UK: White-clawed Crayfish reduced. Austropotamobius pallipes, Southern Damselfly * Vulnerable (RDB Category 2): species likely to Coenagrion mercuriale, Medicinal Leech Hirudo medi- become Endangered unless measures are taken to cinalis and Pearl Mussel Margaritifera margaritifera. reduce threats. Habitats Directive * Rare (RDB Category 3): species with small popula- Annex II of the EU Habitats Directive (92/43/EEC) tions that are in neither of the above two cate- includes the same species listed on Appendix II and gories but which are still at risk. III of the Bern Convention but obliges member states to take steps to conserve the habitats that It should be noted, however, that invertebrate support important populations of these species. populations can change rapidly, often as a result Ramsar Convention (The Wetlands Convention) of extraneous factors, and that RDB listings may The Ramsar Convention establishes criteria by not necessarily reflect current conservation status. which signatory countries may identify interna- Beyond these species, conservation status is tionally important wetlands. Three of these criteria further defined on the basis of geographical are potentially applicable to the habitats of aquatic restrictedness. JNCC identify species that occur in macro-invertebrates. fewer than a hundred 10 km squares within Great 20.4 Conservation evaluation criteria 367

Britain as ‘notable’, analogous to the Pond Action that expected for the habitat present in an undis- category of ‘nationally scarce’. Regionally Notable turbed state. In this way the index is used as an species are those species that occur in more than a indicator of the general ecological condition of a hundred squares but which are uncommon in site and measures the extent to which it diverges some regions. Species of Local Conservation from the ideal, owing to, for example, degraded Importance are those species that are confined to water quality. limited geographical areas or specialised habitats, Other indices provide a more direct indication that are widespread but nowhere common, or that of the conservation status of a site. The Species are suspected of being under-recorded. Rarity Index (SRI) (Pond Action, 1999), for exam- The evaluation of the conservation value of a ple, scores pond species on the basis of their site, however, involves an assessment of the rarity national rarity. These scores are summed for the of the species present as well as of the richness of species recorded at a site and the total divided by the macro-invertebrate community it supports. the number of species present to generate an aver- Aquatic invertebrates have been widely seen as a age rarity score. useful indicator of the status of aquatic habitats. The Community Conservation Index (CCI) ‘Healthy’, natural habitats with high physical (Chadd & Exstence,in press) is an index applicable diversity and good water quality will tend to sup- to lotic and lentic aquatic systems in Great Britain. port more species, particularly species that are It is a useful tool for the evaluation of the conserva- intolerant of pollution, than heavily modified tion status of sites that integrates information habitats. about the rarity and richness of the species Various indices have been developed to facilitate recorded at a site. More importantly, it is suffi- the evaluation and monitoring of aquatic habitats. ciently flexible that it can be adapted to national A variety of indices have also been developed to and regional contexts. express these combined assessments and to allow Both SRI and CCI require species-level informa- comparisons of the status of different sites or the tion. Their data requirements are, therefore, signif- same site over time. Some of these (e.g. RIVPACS, icantly greater than those of indices such as the SERCON) compare the observed community with BMWP, which focuses on 76 families. 21 * Fish

The UK has some important natural fish commu- assumptions are made concerning real changes in nities, which require active conservation via habitat fish abundance. protection and ensuring that other fish species that It can be valuable to examine and monitor the may upset the existing ecological balance are not species composition of fish assemblages; not only introduced to these key sites. can fish communities be important features in Where sites contain Lampreys, Vendace, Shad, themselves but observed changes in species com- whitefish, Smelt, Charr Salvelinus alpinus, Bullhead position may be used as an indicator of fluctuating or other fish species of conservation concern, infor- environmental quality. Some methods such as gill mation on the status of stocks is particularly netting may provide information on a range of important. species, but in some circumstances a range of Whether a fish stock is self-sustaining in the long methods may be required to assess community term is an important attribute: some exploited structure properly. freshwater fish (e.g. Brown Trout Salmo trutta)are The survey methods described in Section 21.2 now routinely stocked with hatchery-reared indivi- are divided into those suitable for running and duals. Stocking can have impacts on locally adapted still waters, running waters only, and slow-flowing fish populations, and stocked fish can give the or still waters only (Table 21.1). impression that a population is abundant when, in The type of information obtainable with a fact, it is not self-sustaining. The distribution of method (presence–absence, population index, successfully reproducing fish is a valuable measure population estimate, etc.) will depend on how it is of the ecological condition of a given river system. applied, or whether it is used in conjunction with Tributaries or main river stretches in which fish are another method such as mark–recapture (Section unable to spawn successfully may indicate, for 21.2.3). The information obtainable with each instance, habitat degradation of various forms or method is described in Table 21.2. barriers to migration. Fisheries surveys can therefore produce important insights into the health of the overall aquatic environment. 21.1 ATTRIBUTES FOR ASSESSING All natural fish stocks fluctuate in abundance in CONDITION response to changing environmental conditions 21.1.1 Population size and degrees of exploitation. Any single measure of abundance is therefore of limited value unless Population size is the key criterion for determining it is viewed in the context of historical change. the condition of fish stocks. Sometimes these are Long-term catch records, for instance for Atlantic expressed as numbers per unit area where they are salmon Salmo salar, can be particularly valuable in based on fisheries survey (e.g. electrofishing) data. helping to determine likely trends in population Care needs to taken when comparing survey data, abundance. Note, however, that indirect measures as juvenile fish densities change rapidly with age: such as catch need careful interpretation before surveys conducted at the same time of year and in

# RPS Group plc and Scottish Natural Heritage 2005. 21.1 Attributes for assessing condition 369

Table 21.1. Methods for surveying and monitoring fish according to type of water body

Methods suitable for Methods suitable for running slow-flowing Methods suitable for and still waters or still waters running waters

Visual surveys: small pools Hydroacoustic sonar Electronic and clear streams (21.2.1) counters (21.2.1) counters (21.2.1) Catch returns (21.2.2) Gill netting (21.2.4) Traps (21.2.3) Seine netting (21.2.5) Lift, throw and push Trawl netting (21.2.6) netting(21.2.7) Electrofishing (21.2.8)

the same areas are required for valid comparisons. For commoner fish species, making estimates of 21.1.2 Breeding success and population population size has been an integral part of com- structure mercial fisheries monitoring and research for The successful recruitment of juveniles and survi- many years. val of adequate numbers of fish to the mature adult Consequently, a large number of techniques stage are of fundamental importance when defin- have been tried and tested over a long time period. ing the condition of a fish stock (population). The Because many species of fish are very mobile and numbers of young fish surviving each year (‘year migratory, population estimates will usually be class strength’) is naturally variable and the scale of made of a species at a certain stage of its life these fluctuations in self-sustaining stocks needs to cycle. Censuses can be made of adult migratory be appreciated before decisions on significant fish returning to streams (e.g. Salmon Salmo salar, departures in stock abundance can be reached. In Sea Trout), or to the sea (Eels Anguilla anguilla)to addition, the physical size and condition of matur- breed or while they are breeding (e.g. salmonid ing fish has a major effect on reproductive output. redd numbers and distribution). Censuses can be Some Salmon stocks, for instance, are dominated made of juvenile fish as they swim downstream as by small summer-running grilse (fish that have smolts and out to sea (salmonids, Shad). spent only one winter at sea before returning to Fish that spend their whole life cycle in fresh fresh water to breed). Such fish are much less water are normally sampled as adults or juveniles fecund (produce fewer eggs) than ‘multi-sea-win- within specific areas of habitat, for instance within ter’ (MSW) Salmon, which have spent 2 or more juvenile nursery habitats. years at sea before returning to spawn at much Artificial structures such as fish passes, which larger sizes. Complex fish populations, which con- concentrate all fish through a narrow channel, are tain these sub-stock components, must therefore particularly useful for setting up monitoring be sampled for size and/or scales to determine size schemes for migratory fish, such as Salmon and and age distributions. Within species such as Sea Sea Trout; where efficient traps are operated, Trout, scale reading can also often reveal the pre- exact population counts can be obtained. This is sence within the population of large individuals, generally only possible on small-scale systems. which have spawned on several previous occa- Indirect assessments of breeding adult population sions; such information is invaluable in under- size can be made by counting the number of spawn- standing the population dynamics and resilience ing sites (e.g. Salmon redds). to exploitation of a given stock. Repeat spawning Limited applicability and do not produce population size estimates Electronic systems can be expensive to construct and maintain Counts need validation Disadvant- ages Bankside counts require no specialist equipment Provides direct estimate of population size Advant- ages Identifi- cation Diving skills Field craft for bankside counts Operation of electronic systems Interpre- tation of sonar signals Expertise required towards more visible species Likely to yield severe underestimates Counters can be very unreliable high flows and species may be difficult or impossible to distinguish Low Biased Good for electric counters under usual stream flow conditions Bankside counts provide basic information only Methods require expensive equipment but generate a large amount of data Can produce rapid and valuable assessment of breeding distributions (redd counts) and location of spawning shoals Diving studies good for habitat use by individual fish good for pelagic shoals Other attributes Efficiency Precision Bias Simple presence/ absence or, at best, rough index (bankside counts) Estimate Hydroacoustics Popula- tion size data Visual surveys are of very limited application (small pools and small clear streams) Only suitable in clear waters for non-cryptic open-water- dwelling species Hydroacous- tic counts estimate good for pelagic lake species and migratory riverine fishes Recom- mended species group Methods for surveying and monitoring fish Direct counts: visual surveys Direct counts: electronic counters/ echo- sounding (sonar) Table 21.2. Method

370 Method dependent upon honest catch- return data being gathered from anglers and/or netsmen. There is potential for either over- or underdeclara- tion of catches, depending upon circumstances Does not require equipment or fieldwork except where subsampling catches for age/length/ body mass data Analysis and interpretation of CPUE data and local knowledge of fishery Sonar methods can be difficult to interpret if similar species present True catches are often under- reported Effort data are rarely available Counters can be validated via video taping Large lake sonar studies require large data sets to cover water CPUE data must be treated with care: poor catches may not reflect low stocks and vice versa Good if catch returns and effort data adequately reported Can yield population structure data if requests made to anglers/ netsmen Index that may not be related directly to varying stock abundance Of very wide application, from marine or river commercial netting operations to anglers’ catch record books or research trap data Catch returns: catch per unit effort (CPUE)

371 Disadvant- ages Passive traps do not generate quantitative population estimates unless combined with a mark–recapture sampling programme Can only be used in waters free of obstructions unless divers are available to de-snag net Requires smooth substrate for efficient capture of benthic Advant- ages Large amounts of fish can be caught with minimal effort Estimates of population structure can be made Intercept traps make good assessment of populations Can catch large numbers of fish in one sample period (this may necessitate stratified subsampling to maximise value of Expertise required Identification Trap deployment Identification Net selection and deployment Results depend on reaction of fish to traps; trappability can vary greatly with season (e.g. Perch seek out traps when spawning) Bottom dwellers and active open- water fish may be missed Mesh size of net dictates whether smallest year classes sampled Low for passive traps Good for intercept traps Good if net is of correct design for site and if deployed correctly Variable, can be very good but spates often ruin sampling efficiency Good for small areas Other attributes Efficiency Precision Bias Population structure Population structure Popula- tion size data Can be absolute estimateorindex depending upon local circumstance Index Estimate via reduced catches over series of sweeps ) cont. Recom- mended species group Adult migratory fish and smolts Resident adult and juvenile fish of any species Any sized fish in slow-flowing river sections and on lakes ( Table 21.2. Method Traps Seine netting

372 species. Even here, fish often burrow into silt to evade net Can be destructive of large numbers of fish relative to population if used indiscri- minately Largely unselective for target species Care needed for rare species Damages substrate Expensive Requires water to be free of obstructions operation and minimise fish casualties) Can enable low-cost quick surveys to establish presence– absence in difficult habitats (e.g. Charr or whitefish in deep lakes) Can yield good population data if programme well designed Good for large water bodies where seine netting is impracticable Identification Net deployment Identification Net deployment Boat handling Open-water dwellers more catch- able Size classes of fish caught depend entirely on size of mesh used For population surveys, gangs of varying mesh- size nets should be used in various locations species may escape Can be high or low depending upon local circumstances Variable: can be high for migrating fish in rivers (often used by poachers) but low for shoaling fish in lakes Low Low Fast-moving structure structure Population Index Estimate Population Usually used on still waters but can be used on rivers where there is little floating debris Most effective with open- water species Note that this method is destructive: few fish survive release from gill nets Bottom-dwelling or pelagic fish Usually used in inshore waters or estuaries, but also in slow-flowing rivers and lakes Gill netting Trawl netting

373 Disadvant- ages Use restricted to shallow waters Potentially dangerous Requires training Expensive equipment Advant- ages Cheap and reasonably efficient for small samples Good method for catching most species Expertise required Identification Net deployment Identification Equipment operation Boat handling Fast-moving species may escape depending on pulse frequency, and species-selective, depending on behaviour Reason- able Good Size-selective, Good for lower sample numbers May be time- consuming for fully quantitative work but quick for base surveys Other attributes Efficiency Precision Bias Population structure Population structure Popula- tion size data Index Estimate Estimates via depletion techniques ) cont. Recom- mended species group Can be adapted for use in all habitats for various species and size classes All Most efficient in shallow streams, less so in larger rivers Still waters need netting off into sections ( Table 21.2. Method Lift, throw and push netting Electro- fishing

374 21.2 General methods 375

is much less frequent in most salmon stocks than during daylight hours. They are, however, some- with Sea Trout but common, for instance, amongst times appropriate for waters that are too shallow cyprinid (carp family) fish species such as Chub to be sampled easily with other techniques and for Leuciscus cephalus, Roach Rutilus rutilus and Dace particular age-classes of fish that inhabit shallow- L. leuciscus. Some species such as Lampreys and water areas. For Bullheads, visual stone-turning Eels are thought invariably to die after a single searches are valuable for presence–absence or spawning. rough population index measures. For successful stock management and conserva- Counts can also be made underwater with the tion, therefore, estimates will often need to be aid of snorkel or scuba-diving equipment; micro- made of the numbers of adult spawning fish habitat selection by stream-dwelling trout, for (spawning escapement), their size and age distribu- instance, has been studied by using this method, tions, and densities of surviving juveniles in nur- which is generally best suited to clear or calm sery habitat areas. As mentioned above, the waters. geographical distribution of successful spawning Automatic counters are often used for counting within a catchment is also an important criterion. migrating salmonids; they do not always distin- Different methods are usually required to mon- guish between sizes or species of fish (photo- itor the different life stages of fish populations. For graphic equipment can be helpful) but they do many methods that involve capturing fish, mark– provide continuous data coverage, given suitable recapture techniques can be applied to generate water conditions, and technological developments more precise estimates of population size. Mark– are increasing their accuracy. Sometimes a size recapture theory is summarised in Section 10.11; limit (e.g. of 50 cm) is used to split Salmon and Sea the applications of the method to fish monitoring Trout: this is not totally accurate (often lumping are briefly considered in Section 21.2.3. large sea trout with salmon), but is a useful method to obtain broad estimates of numbers of upstream migrating fish. Counters themselves are not overly 21.2 GENERAL METHODS expensive, but on larger rivers the structures in 21.2.1 Direct counts which they must be sited can be costly. Hydroacoustic systems can also be used to count Principles fish. They can be oriented to sample the water Many methods for surveying and monitoring fish column vertically or horizontally and can be fixed involve capture. However, in some cases this can be or mounted on boats. They are generally unsuited avoided. A variety of counting methods can be used to shallow weedy waters and have been used to make direct counts, ranging from simple bank- mostly to determine the distribution and abun- side observations, through scuba-diving surveys to dance of shoaling species in large open reservoirs the installation of sophisticated electronic or and natural lakes. acoustic counters. Safety is a key consideration when carrying out Counts made by trained observers have the fieldwork in aquatic habitats. Some key points are advantage that species can be distinguished and described in the previous section, but all safety estimates can also be made of spawning sites and recommendations listed in Part I, Box 2.11 should other attributes of fish populations. Data are, how- be followed where appropriate. ever, usually limited to presence of a given species (absence always being difficult to determine defini- Field methods tively). Note, also, that it is not usually possible to Bankside counts determine the sex of fish from bankside observa- This technique is of limited application. The water tion. Bankside visual counts are cheap, quick and should be surveyed cautiously, wearing unobtru- cause minimal disturbance to fish but are generally sive clothing, polarised glasses and a hat with a very inefficient, as many fish use available cover brim to shield the eyes. 376 21 FISH

Counts should be of sufficient duration to record echoes bouncing off fish to form the basis of the all the fish in view but not too long; if fish move counts. Resistivity counters can detect fish of into the count area from outside during the count, various size ranges and whether they are passing the results will be biased upwards. Remember that up- or downstream. Counters generally need to be it will usually be the case that many fish of all located at permanent sites such as weirs or fish species will be remaining under or within physical passes, although semi-permanent units can be uti- cover (e.g. weed beds), making them difficult to see. lised on small streams for investigatory work. In The area of water visible from each location should clear waters, the videotaping of fish in a counting be estimated, preferably in advance of the survey. chamber can be used to verify counts and identification of different species. In principle, absolute Underwater counts population estimates can be achieved, but in prac- Underwater counts can be either transects or point tice counts tend to be incomplete and can therefore counts (Sections 10.5 and 10.6). They can be made miss an unknown component of a migratory run of by using snorkelling or scuba-diving equipment. fish. This usually happens under spate conditions. The choice will depend on the depth and clarity of Hydroacoustic systems offer the advantage on the water; in general, observations deeper than some rivers of fulfilling a similar function to elec- 1.0–1.5 m in turbid freshwater lakes will require tronic resistivity counters, but they are inefficient scuba-diving equipment (Perrow et al., 1996). under turbulent conditions and thus require care- For transects, the surveyor swims along a fixed ful siting. Sonar set-ups can, however, be used to cord marked at regular intervals. The number and survey in areas in which other techniques are not size of fish within a given distance of the transect practical, for instance, in the depths of deep lakes line are recorded. This distance will depend on the and lochs. Shoals of fish show up as clouds of range of visibility. If the limit of visibility is mea- echoes on the screen, with air-filled swim bladders sured, the transect area can be calculated. It is best giving distinctive traces. Differing species and sizes to record fish at a small distance ahead, because of fish can be discerned by experienced operators. they may well move out of the transect area at the It is beyond the scope of this Handbook to cover approach of the observer. Swimming speed should the design and installation of fish counters or sonar be kept constant and slow; faster speeds will intro- equipment; for further information, see Cowx duce greater inaccuracies. (1996) and Templeton (1995). At the time of writing Point counts are generally carried out with the Environment Agency is undertaking a funda- scuba-diving equipment from a set location for a mental fisheries monitoring review, including the set amount of time. Surveyors should remain still efficiency and applicability of fish-counter facil- on the bottom for a while before starting the count ities. Appendix 6 lists the field equipment required to let the fish become accustomed to their pre- for surveying and monitoring fish by direct counts. sence. The radius of visibility should be estimated after the count in order to calculate the area Data analysis and interpretation surveyed. Bankside counts A GPS can be used to relocate sample points with Observation data will often be limited to presence a greater degree of accuracy than is obtainable with of a given species. Data from each sample location compass bearings on large water bodies. can be used to estimate minimal density if the area visible from the sample points has been estimated. Electronic counters and hydroacoustic If the whole river has been surveyed, an index can systems be derived of the total number of fish. This method Automatic electronic counters record the upstream will normally underestimate fish populations, or downstream movement of fish. Resistivity coun- because many fish will be hidden during the ters detect fish passing over electrodes beneath the count period. However, during the breeding sea- counting chamber; hydroacoustic counters use son, when some species of fish hold territories or 21.2 General methods 377

are concentrated into small areas for spawning, CPUE data can therefore provide an index of actual this error may not be too great. Counts can other- fish population size as long as the results are trea- wise be used as an index of population size. ted with caution. Recent research on long-term Statistical analysis of bankside count data fluctuations in Sea Trout catches from a variety of should only be made if the data are reliable (i.e. English and Welsh rivers indicates that catch data the bias is consistent and understood). Statistical probably do represent a useful index of fish popu- comparisons of counts from different years can be lation size. made by using standard tests (Part I, Section 2.6.4). Note, however, that spring Salmon can be very susceptible to capture by angling soon after enter- Underwater counts and transects ing a river but less susceptible after being in fresh Analysis of underwater point count or transect data water for some time. Under suitable conditions, should follow the principles detailed in Sections low fish stocks can give rise to good catches 10.7 and 10.8. If the area of visibility is known, a whereas under adverse conditions high stocks simple density estimate can be made from this and may be virtually uncatchable. The likelihood of the total count, but some effort should be made to capture of fish can change with length of time in account for the decrease in detectability as distance fresh water, recent movement history, sexual increases (Section 10.6) unless fish were only maturation, weather, angler skill, type of netting counted in an area of 100% visibility. Counts or den- gear or angling technique and skill of deployment, sity estimates can, potentially, be analysed by using etc. A detailed knowledge of the fisheries con- standard tests (Part I, Section 2.6.4). Other popula- cerned is a prerequisite for sound analysis and jud- tion parameters such as age-class ratio (based on gement of likely trends in abundance. size) can also be estimated and tested if recorded. Always compare ‘like with like’ CPUE data when assessing whether fish stock abundance may be Electronic counters and hydroacoustic changing year on year. Be particularly careful to systems allow for season and method restriction changes Analysis of electric counter data can be made by as these may not be quoted in any overall catch calculating the total number of fish passing the return figures. Further problems with CPUE ana- counter over a set period and comparing counts lyses can involve the difficulty of obtaining accur- between years. Trends may be established by ate net and rod catch returns from anglers, and using techniques such as regression analysis. the problem of establishing actual effort expended. Analysis of hydroacoustic data is a specialised Differences in the technological sophistication of field, and cannot be covered in detail here. Refer angling or commercial fishing equipment (e.g. a to Templeton (1995) for further details. change from traditional multifibre to nylon monofilament nets) result in differently sized catches for 21.2.2 Catch returns the same time spent fishing. More information must therefore be collected to enable actual effort Principles deployed to be estimated. The collection and analysis of catch information from fishermen (anglers and netsmen) potentially Field methods gives access to a large amount of data. Catch A variety of methods can be used to collect angler returns can be used to calculate CPUE (catch per and commercial fishery catch data. Most methods unit effort) data (e.g. fish angled per hour or involve the use of third-party recording, including Salmon caught per haul of a seine net) if the the use of log books and postal questionnaires or amount of time spent by the angler in catching sub-sampling commercial catches and the collec- fish or the number of net or trap days is known. tion of statutory catch returns. Allowances have to The more fish caught per unit effort, generally be made for under-reporting of commercial catches speaking, the higher the number of fish present. and potential over-reporting from angling fisheries 378 21 FISH

(which could raise the capital value) if any true population indices by fixed-effort sampling relationship with actual fish stock abundance is programmes. to be reliably established. For a more detailed treat- Fish traps fall into two broad categories: those ment of this subject see Cowx (1996) and King such as baskets, pots and fyke nets, which are port- (1995). Data can also be obtained from fish caught able and used for both non-migratory and migra- in intakes and screens. tory fish species, and those that intercept up- or downstream migrants based on trapping barriers Data analysis and interpretation or weirs. Problems associated with the use of CPUE data Non-interceptory traps come in a variety of include the ability and willingness of anglers and designs, but most rely on the funnel principle netsmen to make accurate returns, species bias, whereby fish pass easily through an entrance hole and the quantification of effort. This last point, in but are unable to find their way out again. Returns particular, makes analysis and interpretation of from these traps are dependent upon the behav- results difficult. Where long-term datasets are iour of the fish in relation to the type of trap used. available they can, however, be very useful. They are thus considered generally unsuitable Examples on major rivers have shown previous for the quantitative assessment of non-migratory declines in the abundance of multi-sea-winter fish populations. However, they can be useful for (MSW) fish and corresponding increases in grilse determining other population parameters of target abundance. Such results show, for instance, that species (e.g. estimating age structure, growth or current Salmon declines could be a periodic, rather condition (Cowx, 1996)). than a one-off phenomenon. Traps for migratory fish are usually perman- In principle, the numbers of fish caught by ently installed on structures such as weirs or sal- anglers of a certain species in a particular river or mon ladders, and are a convenient method of water body over a certain period can be treated as catching returning adults, downstream-migrating an approximate index of population size. Data for juveniles or Eels. Population estimates can be made differing species will produce varying relationships from larger rivers by using mark–recapture techni- between CPUE and actual stock abundance. ques between traps, and direct total population Data from intakes or screens can be used for counts can be made on small, intensively trapped presence–absence of species and indices of abun- channels. Partial estimates (in which an unknown dance of a given species from year to year. In prin- proportion of the run is caught at a given point) can ciple, many other types of data can be collected be combined with mark–recapture studies to from dead fish obtained from intakes, screens obtain total migrating population estimates for a etc., such as growth rates, age, DNA and morpho- given river system. metrics. However, this is likely to be far beyond the scope of most survey and monitoring programmes. Field methods Provided the problem with catch return data can Baskets, pots and fyke nets be addressed, trends in catch returns from differ- These traps (Figure 21.1) are portable. They can be ent years may be analysed with techniques such as set in a pattern along the shoreline or partially regression. Other kinds of statistical analysis may across a river and used to catch Eels, salmonids also be appropriate (see Part I, Section 2.6.4). and other species. Pot and basket traps can be thrown from boats or from the bank or placed by 21.2.3 Traps wading in shallow water. The position of each trap should be marked with a float; traps in deeper Principles water should be on ropes so that they can be easily Trapping fish allows the possibility of establishing retrieved. Fyke nets need to be more carefully set direct population counts, inferred estimates by and fitted with Otter guards to prevent drowning of depletion or mark–recapture experiments, or these animals. When set from a boat the net should 21.2 General methods 379

fin clip) before reliance is placed on quantitative Pot trap results. Fish can also be fin-clipped to allow identification. This can be combined with microtagging in the nose cartilage with tiny coded wire tags, which are electronically read on recapture of the fish. This system is widely used for batch or individual tagging of Salmon parr and smolts to Shoreline Fyke net determine, for instance, the survival at sea of wild smolts or the survival of hatchery-produced stocked juvenile Salmon. Other forms of external tag (e.g. numbered Floy tags) can also be used on fish. For further details on the marking of fish see Figure 21.1. Pot traps and fyke nets. Source: Perrow Templeton (1995). For further information on et al. (1996) mark–recapture theory see Section 10.11. Refer to Appendix 6 for a list of the equipment required be placed on the bow with the leader on top. The end for monitoring fish by trapping. of the leader is anchored, and is let out as the boat Trapping should usually be carried out continu- moves backwards. The hoop net is put overboard, ously for the period of fish movement under obser- stretched out and the end is anchored. One leader vation. Many fish move under cover of darkness or should extend perpendicular to and near the shore during spates, and trap emptying should take to prevent fish from swimming around the trap. account of this behaviour. If migratory fish are being monitored, trapping should be timed to coin- Permanent traps cide with the peak of adult or juvenile migration. These traps can be designed around previously constructed structures such as weirs or fish ladders or Data analysis and interpretation sited in purpose-built facilities. These will require The analysis of passive trap data is complicated by engineering design and will therefore tend to be the fact that captures will depend upon the behav- expensive, especially on larger rivers. The design iour of the fish and the size of the trap. It is unlikely and construction of these will depend upon the that a previously captured fish would exhibit the location for which they are intended. For further same likelihood of being caught again and this details see Templeton (1995) and Cowx (1996). change in awareness (i.e. trap shyness) biases recap- Whichever method of trapping is used, traps ture frequencies. In addition, some fish (e.g. Perch should be checked at least once a day, and the Perca fluviatilis) differ greatly in trap susceptibility trapped fish should be identified, aged and through the year. Population estimates cannot released. Trapped fish can be tagged or marked in therefore be made with any degree of reliability a number of ways for a mark–recapture study. with these types of trap. However, a population index, such as the mean number of fish per trap or Marking fish fish caught per day, can be used. Results can poten- The most commonly used and successful method is tially be compared statistically by using standard to mark the fish with Alcian blue dye, using either a tests (Part I, Section 2.6.4). syringe or a ‘Panjet’ (compressed air tattoo gun) Intercept trap data can be used to derive total inoculator. Recently, fluorescent biocompatible population counts. For example, if a trap is set in a silicone-based elastomers have been produced. fish pass you can be reasonably certain that all the These can be injected under the skin or between fish that pass through have been caught. In inten- fin rays to allow batch marking of differing sively trapped narrow channels, this can be treated classes of fish. Retention should be checked by a as an estimate of total population size. In wider double-marking procedure (e.g. elastomer and a channels, only a proportion of the population will 380 21 FISH

be caught. That proportion can be estimated by needed for gill nets to be routinely untangled and marking all the fish caught in one trap and looking set so as to fish efficiently. Each end of the net has a at the proportion of marked fish caught in another long cord with a buoy attached for judging the posi- trap further along the migratory route. The ana- tion of the set net and to aid relocation. For a general lysis of mark–recapture data is covered in more survey of an unknown 5 ha still water, where the detail in Section 10.11. investigator wishes to assess the fish community structure, it might be sufficient to set a total of six 21.2.4 Gill netting different 30 m lengths of nylon gill net with mesh sizes from 1 cm up to 5 cm bar length. The nets Principles should be set from the shallow littoral down into Synthetic twine or nylon monofilament gill nets the depths to fish for a single night and recovered are supplied in a wide variety of mesh sizes, meas- early the next morning. Care is needed where rare ured either along one side of the square (‘bar fish-eating birds occur, as it is not unusual to drown length’) or as a ‘stretched mesh’ (pulled tight cor- birds in nets as they seek to plunder the enmeshed ner to corner). The nets are readily available and fish. Gill-netted fish are usually killed immediately inexpensive. The top line is buoyed up by a row of by concussion and then stored in a coolbox for sub- cork or polystyrene floats and the bottom lightly sequent laboratory analysis. Where fish are weighted. Gill nets catch fish by enmeshing them, intended for release they should be handled very usually behind the gill covers. Spiny-finned species carefully. Greater survival is likely from relatively such as Perch can take some disentangling, and thick and soft-meshed nets, which have been fished waters in which there is a great deal of floating for short periods (an hour or two) only. As a last debris cause gill nets to become clogged, necessi- resort with important specimens, nets can be cut tating long tedious cleaning sessions. In relatively to release fish quickly and with minimal damage. clear open water, however, gangs of gill nets can be On some waters enmeshed fish are often attacked set anywhere from the surface down to the bottom and partly (or completely) devoured by Eels; the and, in skilled hands, can represent a cost-effective likelihood of this can be lessened by daytime fishing form of fisheries survey. Care must be taken not to with gill nets although this, in turn, will bias the set too many nets in a given water body as, on sizes and species of fish likely to be caught. occasions, shoaling species can be caught in large numbers and this could adversely affect the con- Data analysis and interpretation servation status of rare fish and create logistical Interpretation of gill-net catch data is not easy as problems of handling time. Lost nets may carry on catches tend to be very variable. This is particularly fishing for long periods in the depths of a lake and so thecaseinlargelakesandwithshoalingspeciessuch it is important to tether and recover them securely. as white fishes. Experience of netting a given site In addition, it is unusual for fish to survive gill net- brings with it a degree of predictability of catches. ting: the skin and/or fins are often badly damaged, Presence (but not absence) data and CPUE (Section either through abrasion while in the net or during 21.2.2)arethemostreasonableanalytical the process of removing the fish from the net. Gill- approaches. Note that gill-net catch data are, by the netted fish are therefore often killed and used for very nature of the equipment used, very size-biased. complete analyses of length, mass, sex, growth, diet- Scale readings can be used with many species to ary and, perhaps, DNA, or other, studies. check that all year classes are represented in catches.

21.2.5 Field methods 21.2.6 Seine netting

Gill nets set on a lake bed are usually set from a flat Principles board on the back of a rowing boat. The boat is A seine net is a wall of netting with floats at the top rowed slowly along as the net is paid out. Skill is and weights at the bottom. Seine nets are often the 21.2 General methods 381

only practical way of catching smaller fish in still not in contact with the substrate, both lines are waters. They can be adapted to suit many situations pulled quickly at once; this is a very hit-and-miss and are efficient in terms of costs and labour pro- approach and is unlikely to produce unbiased vided the net is not too large. Nets are designed for results in terms of fish community structure. specific water bodies; a truly general-purpose net is Removing the trapped fish from the net is done not available. Water depth, substrate type, fish in small stages by pulling the net in by a small species, and specified mesh size and length of net distance each time and removing fish with a dip will all affect the specific design of net required. net or by hand. The fish should be identified and Seine nets are limited principally by the require- other attributes measured if required. Fish can also ment of a good bed profile over which to set and be marked for mark–recapture studies (see haul in the net. They are used most easily in rela- Sections 21.2.3 and 10.11). The field equipment tively shallow waters, free of obstructions (natural required for monitoring fish by seine netting is or artificial); if a scuba-diver is unavailable, snagging listed in Appendix 6. the net may tear it and incur considerable expense as well as wasting time while the net is freed. Data analysis and interpretation The method is relatively unselective, although Density of fish can be estimated from the number of fish in the littoral margins are undersampled and fish caught in a seine net spread over a given area, fast-moving species or those able to burrow into a and depletion techniques can be applied to data soft substrate may escape. from successive nettings. This estimate will probably be lower than the actual amount, because Field methods some fish will not be captured. Estimates obtained The length and width of the net will depend on the with seine nets are indices of population size, unless size of the water body. In shallow water the depth the entire water body is netted, which is only possi- should be 1.5 times the depth of the water (Buckley, ble for small ponds. Even then it is usual for many 1987). A reasonable number of hauls should be fish to remain in the mud at the bottom, evading made to obtain a good sample of the population. capture. Counts or densities from different years This needs to be judged on the site according to can potentially be compared statistically by using the success of the operation. It is usual to subsample standard tests (Part I, Section 2.6.4). For details of the size classes of fish at random when collecting scales, analysis of mark–recapture data see Section 10.11. length or body-mass data for subsequent analysis. A known area of water is encircled with the net. The net is fixed at one end (to the shore, a boat or a 21.2.7 Trawl netting buoy), and the rest of the net is laid out (from a Principles boat, or by wading in shallow water) in an arc or Trawl netting is used for catching fish that live on semicircle and then returned to the fixed point. or near the bottom of large rivers and lakes. The Potentially, the fish may be frightened away while applicability of this method is limited by the need the net is being set. To minimise this problem, set for a boat capable of handling trawl nets and the the first part of the net quietly and close the gap to size of water body on which boats of a suitable size the fixed station as quickly as possible. can be used. Hauling the net in is usually done by at least two A cone-shaped net is towed along the bottom, or people, one on the rope at each end of the net. If the through the water column at a set depth. There are net is in shallow water and covers the entire water several types of trawl net; the most commonly used column, the float line is pulled first, and slowly to ones are: ensure that the bottom of the net does not rise up. When the haul is almost complete, the weight line * mid-water or surface trawls, in which the mouth is pulled up and out from underneath the net, of the net is fitted with floats at the top and trapping the fish. In deeper water, when the net is weights at the bottom to keep it open; 382 21 FISH

* beam trawls, which have a horizontal bar on the Headrope headrope and a rectangular frame and rows of chains set in front of the groundrope to disturb fish in the bottom sediment; and * otter trawls, another type of bottom trawl in Midwater trawl net Warp which the net is kept open by water pressure on Groundrope Weight boards attached at an angle to the towing line. Beam The different types of net are shown in Figure 21.2. Beam trawls can cause significant damage to the substrate, and all trawls can injure fish when they are packed together in the net. Tickler chains Beam trawl (for bottom trawling) Trawling is useful for slow-flowing water bodies in which the flow would make seine netting impracticable, and for water bodies such as tidal rivers, which are too saline for electrofishing. However, it is limited to waters that are relatively Otter boards free of obstructions and is a time-consuming and expensive method of monitoring fish. An alterna- Otter trawl (for bottom trawling) tive approach in large slow-flowing rivers is to use an electrofishing boom boat, which has built-in Figure 21.2. Types of trawl net. Source: Perrow et al. cathodes and hand-held anodes. Fish are attracted (1996). to the anodes, stunned and netted out.

Field methods Trawl depth equals line length multiplied by sin For both bottom and mid-water trawls, the net is (908 –angle). towed from the stern of a boat. The net is fed into When the trawl is complete, the lines are pulled the water by hand (requiring at least two people). in. Care should be taken to ensure that the net does When the net has been let out, the otter boards (if not catch the propeller or engine of the boat. To an otter trawl is used) are lowered into the water standardise surveys and estimate the volume of and positioned by keeping the lines tense. The lines water or area of substrate sampled, the distance are fed out evenly and kept under tension by two covered by the net must be known. This can be people. Marks along the lines are used to feed out achieved either by trawling between two markers the required amount of line for the desired trawl set on the banks or by towing at a set speed for a set depth. The lines are fastened to the stern of the time period. The latter method is more appropriate boat. on larger water bodies. Appendix 6 summarises the The net must be towed at a speed faster than equipment that will be needed for surveying fish by that which the fish can sustain, tiring individuals trawl netting. gradually dropping back into the bag of the net and being captured. The most effective trawling Data analysis and interpretation speed varies from 1.5 knots for slow-moving Trawling produces a semi-quantitative index of bottom-dwelling fish to 5 knots or over for faster population size. Catch per unit effort statistics species (Perrow et al., 1996). Line length for can also be calculated from trawl data. The num- bottom trawls should be roughly three times the bers of fish caught over a certain length of trawl depth of the water. Towing a mid-water trawl at can be used to monitor populations, and compar- the correct depth can be achieved by measuring isons can potentially be made statistically by using the angle of the lines relative to the vertical. standard tests (Part 1, Section 2.6.4). 21.2 General methods 383

attachment dissolves, the net rapidly rises to the 21.2.8 Push, throw and lift netting surface, catching the fish above it as it does so. Principles Buoyant nets are particularly good for capturing These methods involve small hand-operated traps, fish larvae and small fry in still waters. which are typically used to capture small fish in All these methods are simple to perform and shallow waters, which are still or slowly flowing. easily standardised after some practice. They are Salmon fry can also be captured on fast-flowing cheap, but can be labour-intensive if a large num- sections by the use of a ‘banner net’: a simple bag ber of samples are required. of mesh spread between two rods and held downstream of an electrofishing anode. Hand-held nets Redd nets can be used to make absolute estimates of local Mesh netting, which catches emerging fry, can be population density, which can be expanded to an pinned down around a salmonid redd to obtain overall population estimate if the traps are estimates of the numbers of young fish emerging deployed in a sufficient number of representative in the spring after winter incubation. This techni- discrete sampling points. As they are not passive que can be used on silt-laden rivers to help estab- traps, they are less dependent on the behaviour of lish whether ovum incubation success is high the fish in relation to the trap and so produce or low. results that are fully quantitative. The equipment necessary for surveying and monitoring fish by push, throw and lift netting is Field methods listed in Appendix 6. Push nets Push nets are similar in design to trawl nets in that Data analysis and interpretation they have a net attached to a frame, which keeps Data from push, throw and lift nets can be used to the net open. The frame has handles, which are generate absolute population estimates if sample used to push the net through shallow water by points are representative of the water body as a wading. The number of steps taken should be stan- whole. The number of fish caught in a given area dardised on each occasion. can be extrapolated over the whole site area to give a total estimate. Care must be exercised with data Throw nets analysis as fish often shoal, leading to non-uniform Throw nets are circular with weights around the distributions within water bodies. edge. They have a central line, which is used to pull Data from different years can potentially be ana- the net in after casting. It requires practice to throw lysed statistically by using standard tests (Part I, the net correctly so that it opens to its full extent Section 2.6.4). before hitting the water. This is important in order to ensure that methods are standardised. Fish are trapped in the net as it folds up when pulled in. One 21.2.9 Electrofishing design has a purse line, which closes the bottom of Principles the net to prevent fish from escaping as the net is Electrofishing is one of the most commonly used pulled in. methods of catching fish for surveying and monitoring purposes. It can be applied to most species Lift nets and locations, but it is particularly useful for moni- Lift nets come in two basic types. Hand-held scoop toring juvenile fish populations in rivers and nets are simply pushed below the surface and streams. brought up rapidly. Buoyant nets lie on the bottom An electric current is passed through the water attached to a weighted frame with dissolving through electrodes; the current draws fish towards tape, glue, or (originally) a Polo mint. When the the anode (‘galvanotaxis’), stunning them and 384 21 FISH

making them easy to capture and record. references before attempting to carry out any sur- Electrofishing units may be AC or DC; pulsed DC vey work. Refer to Cowx & Lamarque (1990) and is most commonly used because it causes less Cowx (1990) for further information on the oper- damage to the fish. Amperages of currents used ation of electrofishing equipment. must be carefully regulated so that the fish are Puhr (1998) has produced an electrofishing pro- stunned effectively without the current being so tocol, which sets out a standard survey method- high that their muscles are thrown into severe ology with the aim of producing data that are contractions, damaging their vertebrae and spinal comparable between sites. This should be followed nerves. The strength of current passing between where appropriate. the electrodes is affected by water chemistry (con- Electrofishing is generally carried out by chest ductivity) and physical factors such as the amount wading or from boats, although smaller streams of weed growth. The frequency with which the DC and ponds can be fished on foot with thigh waders. is pulsed through the water affects the length of Sections of a set length are fished, and stunned fish fish most efficiently stunned. For this reason it is are recorded (e.g. length, mass, etc.). Sections can important that any comparisons of electrofishing be marked out with stop nets; in this case, the data should ideally be made by using similarly set contained area can be fished repeatedly until machines operated by the same team of people. most of the fish have been caught; total numbers This will ensure that minimal variability is intro- can then be estimated by using the removal duced into the dataset and that comparisons are method (Section 10.8). This produces numbers per valid. It is also worth noting that the efficiency of unit area of habitat with associated confidence electrofishing is affected by turbidity, current intervals around the population density estimates velocity, water depth and the alertness of the net- for each species. ting personnel. Data for individual species can be broken down Electrofishing can be used to make total popu- into size classes and presented as separate ana- lation estimates for a given stretch of river by lyses. Mills (1989) provides a useful description using multiple catch techniques (fishing with respect to Atlantic Salmon ecology. It is upstream two or three times between stop nets) worth noting that, of all the methods described in or indices of population size (semi-quantitative this section, electrofishing is by far the most widely sampling) by using single fishing surveys (often used for juvenile salmonid population assessment. downstream, down the centre of the river). It is The field equipment requirements for surveying possible to establish regression relations between and monitoring fish by using electrofishing are multiple-catch estimates and single-sweep esti- listed in Appendix 6. mates for a given type of river such that single- sweep estimates can subsequently be corrected reasonably accurately to provide reasonable quan- Data analysis and interpretation titative population estimates (see Section 21.2.3, Estimates of total population density can be made Salmon juveniles). by using the removal method (Section 10.10) if a set area is marked out and fished intensively. Alternatively, numbers caught along a transect Field methods can be treated as population indices. It has now A detailed methodology for electrofishing is not been established that single-run electrofishing sur- included here. Electrofishing can be a highly danger- veys (‘semi-quantitative surveys’) bear a fairly good ous operation and users should be adequately relation to fully quantitative approaches, thus sav- trained and experienced in the method. It is there- ing much sampling effort and expense while sacri- fore recommended that anyone wishing to under- ficing little precision. take electrofishing surveys should attend a training Indices or estimates can potentially be analysed course and consult more specific methodological by using standard tests (Part I, Section 2.6.4). 21.3 Fish conservation evaluation criteria 385

Although the Sturgeon, a priority Annex II species, 21.3 FRESHWATER FISH CONSERVATION has occasionally been found in UK rivers, it is very EVALUATION CRITERIA infrequent and may be extinct in the UK at present, Key evaluation considerations and as such no SACs have been put forward for this species in the UK. Similarly, Houting Coregonus Catch data can provide a large amount of informa- oxyrhynchus is also listed in Annex II but has no UK tion from which the status of fish populations may designated sites as it is now considered extinct be determined. However, these data are subject to in the UK. certain sampling errors, particularly the variability Sturgeon and Houting are the only UK or for- in fishing effort, which may change with environ- merly UK species that are listed in Annex IV of the mental variables, such as weather, as well as Habitats Directive as species of community interest human factors such as angling skill and accuracy in need of strict protection. of reporting. Annex V of the EU Habitats Directive includes Fish records from the Environment Agency and the following UK species whose taking in the wild others have been brought together in the DAFF and exploitation may be subject to management (Database and Atlases of Freshwater Fishes) project, measures: Sturgeon, River Lamprey, Grayling, from which an atlas has recently been produced. Vendace, Whitefish species, Atlantic Salmon, (Davies et al., 2003). Previously, the most recent Barbel Barbus barbus, Allis Shad and Twaite Shad. distribution data were published in 1972 in the Key to Freshwater Fishes by Peter Maitland. Ramsar Convention (The Wetlands Convention) General criteria for the designation of wetlands of Protection status in the UK and EU international importance that cover fish are criteria 2, 3 and 4. Bern Convention Criterion 2 guidelines urge contracting parties Signatories to the Bern Convention have agreed to to include in the Ramsar list wetlands that included protect fish species listed in Appendix III. threatened communities, or wetlands that are cri- Freshwater fish species occurring in the UK that tical to the survival of species identified as vulner- are listed in the Bern convention include the able, endangered or critically endangered within River Lamprey Lampetra fluviatilis, Brook Lamprey national endangered species programmes or inter- Lampetra planeri, Sea Lamprey Petromyzon marinus, national endangered species frameworks, such as Allis Shad Alosa alosa, Twaite Shad Alosa fallax, the IUCN Red Lists. Vendace Coregonus albula, Whitefish Coregonus spp., Criterion 3 guidelines cover species considered Grayling Thymallus thymallus, Atlantic Salmon Salmo internationally important for maintaining the bio- salar, Spined Loach Cobitis taenia, Wels Siluris glanis logical diversity of a particular biogeographic (introduced to Britain) and Common Goby region. Characteristics sought under this criterion Pomatoschistus microps, an estuarine species. are ‘hotspots’ of biological diversity, centres of Additional details on the Bern Convention can endemism, the range of biological diversity occur- be found online at www.nature.coe.int/English/ ring in a region, a significant proportion of species cadres/bern.htm. adapted to special environmental conditions, and wetlands that support rare or characteristic ele- Habitats Directive ments of biological diversity of the biogeographic Annex II of the EU Habitats Directive (92/43/EEC) region. includes the following species as requiring the des- Criterion 4 guidelines seek to include wetlands ignation of Special Areas of Conservation (SACs): Sea that provide habitat to support species at a critical Lamprey, Brook Lamprey, River Lamprey, Sturgeon stage of the life cycle or provides refuge during Acipenser sturio, Allis Shad, Twaite Shad, Atlantic adverse conditions. This could cover areas that pro- Salmon, Spined Loach and Bullhead Cottus gobio. vide habitat for breeding fish. 386 21 FISH

Fish-specific criteria for the designation of wet- to the silting up of previously suitable breeding lands of international importance are criteria 7 and 8. sites. Criterion 7 indicates that a wetland can be desig- Decline of some fish populations can be attrib- nated as of international importance if it supports a uted to the introduction of non-native fish species high diversity of fishes and shellfishes. Diversity in such as the Zander Stizostedion lucioperca, which eats this context includes not only species richness, but native fish species. Introduced fish may also bring also interactions and life history stages. new diseases to river systems. Under criterion 8, a wetland should be considered as of international importance if it represents UK BAP an important resource for fish stocks in terms of Fish species in the UK BAP include the Allis Shad, food, spawning ground, nursery, or migratory Twaite Shad, Vendace, Pollan Coregonus autumnalis, pathway. Houting and Burbot. The BAP for the UK-extinct Burbot seeks to find out the causes of the extinc- Wildlife & Countryside Act tion and consider the feasibility of reintroduction. In the UK fish that are protected under Schedule 5 The BAP for the UK-extinct Houting seeks to con- of the Wildlife & Countryside Act 1981 (amended tinue monitoring for the presence of the species 1985) include the Sturgeon, Allis Shad, Twaite and protect the species in UK waters if re-discov- Shad, Vendace, Whitefish Coregonus lavaretus ered. Further information is available at www.uk- (Gwyniad, Skelly or Powan), and Burbot Lota lota bap.org.uk/library. (which is probably extinct in Great Britain). These species receive strict protection, apart from Allis Sites of Special Scientific Interest Shad, which is protected against killing, injuring SSSI criteria for designating sites for freshwater and taking, and Twaite Shad, which is only pro- and estuarine fish interest are described in the tected against damage to its place of shelter or Guidelines for Selection of Biological SSSIs (NCC, 1989). protection. One aspect of the criteria is that diversity will Conservation status in the UK not usually be a valid criterion for selecting SSSIs, because of the distortion of fish populations by Of the 38 species of freshwater fish native to introductions. Therefore, criteria are based upon Britain, two are rare, three vulnerable, and three ecotypically or genetically distinctive fish popula- endangered. Some other species, such as Eel and tions, for which the site with the largest population Sea Trout, have also declined in numbers in recent of any fish in an Area of Search may be selected, decades (Environment Agency, 2004). and nationally rare species, for which all breeding Pressures on UK freshwater fish are mainly from sites qualify. The nationally rare species are obstructions to migration, pollution and habitat defined in the guidelines as: alterations. Many fish species require clean, well- oxygenated water for their eggs to develop. Species * Vendace such as the salmonids, which lay their eggs in * Whitefish gravel, require a substrate that is free of fine sedi- * Allis Shad ments that would hinder the flow of water (and * Twaite Shad therefore dissolved oxygen) around the eggs. * Burbot (probably extinct). Dredging, changes in the flow rate of rivers, bank erosion and possibly soil and organic matter Some breeding sites of the nationally uncom- washed off arable fields in winter may all contribute mon species Smelt Osmerus eperlanus also qualify. 22 * Amphibians

Amphibians have a terrestrial and an aquatic phase place and eggs have been laid. With some species, to their life cycle, with the larvae being exclusively population estimates can also be made from the aquatic until they metamorphose. Adults return to number of egg clusters. Second, trapping larvae at water every year to breed but spend a proportion of various stages of development will establish each year on land. Amphibians also hibernate over whether eggs are hatching and larvae are surviving. winter. Most surveying and population monitoring Breeding success may be estimated by observing of amphibians focuses on population studies of the number of metamorphs (the term for the stage adults at breeding sites. It is important to remem- immediately after metamorphosis, when the ani- ber that the numbers of amphibians counted by mals emerge from their natal pond) leaving the using most methods are influenced by air and soil pond during summer, and making a comparison temperature: a cold spell may reduce activity con- with adult population estimates. This provides an siderably. This must be taken into account when indication of the productivity of the pond. comparing studies between years or between sites Evaluating metamorph output requires careful or when assessing a site as part of an EIA study. monitoring of larval development in order to ascertain when emergence is imminent. For anurans (frogs and toads), absorbance of the tail provides 22.1 ATTRIBUTES FOR ASSESSING an indication of immediate emergence, although CONDITION the tail is not entirely absorbed prior to emergence. 22.1.1 Population size For common toads, metamorph emergence normally occurs in late summer, and toadlets will Estimates of population size for amphibians are leave the pond en masse. Emergence of Natterjack generally best made during the mating season, Bufo calamita toadlets may be staggered. when most adults will be gathered at their breed- Metamorph output is variable (Oldham, 1994; ing sites. Breeding population size can therefore be Cooke 1995) and therefore evaluation of sites estimated for each pond, with a total estimate for should not be based on data from a single year. an area obtained by totalling numbers from each Young amphibians do not migrate en masse to the pond. This will probably be an overestimate of breeding site, so the number of juveniles caught population size, because movement between entering the pond at the start of the breeding sea- ponds is likely. son will not be a representative sample of the total juvenile population. Little is known about the life 22.1.2 Breeding success history of juvenile amphibians; estimates suggest that the adult population represents only about Whether or not amphibians are breeding success- 20% of the total population for Great Crested fully can generally be examined in two ways. First, Newts Triturus cristatus (Oldham, 1994) and 10% for egg searches will establish if mating has taken Common Toads Bufo bufo (Latham, 1997).

# RPS Group plc and Scottish Natural Heritage 2005. 388 22 AMPHIBIANS

22.1.3 Survival and mortality 22.2.1 Newts

Estimates of survival and mortality can only be The English Nature guidelines for Great Crested made reliably by mark–recapture studies; survival Newt mitigation (English Nature, 2001) provide a is calculated through analysis of marked individ- suitable survey standard to establish presence– uals recaptured on subsequent occasions. Unless absence, and a population size class estimate. dead animals are found, it is not usually possible These can be applied to all newt species in the UK to distinguish between mortality and emigration. and provide guidance on the survey intensity and Similarly, immigration and births can be easily timing required. The guidelines are summarised in confused, unless you are certain that the popula- Table 22.2. tion is isolated. For toads and Great Crested Newts it is believed 22.2.2 Natterjack Toad that dispersal occurs during the juvenile stage. Given that most population marking is centred on Qualitative surveys for the Natterjack Toad can be the adult population, emigration and immigration carried out by listening for calling males, or by maybeconsideredtobeunimportant.Survivalof searching for animals in refugia, for spawn strings, juvenile cohorts can be estimated by comparing esti- or for animals at night. To assess the population mates of metamorph output with numbers of adults. size, estimates can be made by counting spawn strings. Searching for adults should be carried out 22.2 GENERAL METHODS between spring and autumn, on humid warm nights. Spawn strings will be present in ponds A general survey for amphibians would start with from early April to June. It is recommended that an assessment of the suitability of the habitat. the ponds be surveyed weekly during this period to A key requirement is a water body, but even if establish population size (Beebee & Denton, 1996). this is absent, amphibians may be present in the terrestrial phase of their lifecycle. Once the habitat 22.2.3 Torch counts has been assessed, the survey can start. Table 22.1 outlines the general methods available for survey- Principles ing and monitoring amphibians, but the survey Torch counts are most appropriate during the techniques used will vary according to the aims of breeding season for species that exhibit aggregat- the survey, the time of year, and the target species. ing behaviour. For example, newts can be surveyed Further guidance can be found in Buckley & Inns by conducting torch counts around ponds in which (1998). they are breeding. After nightfall, male newts hold For designated sites (i.e. ASSIs, SSSIs, SACs) the territories and display around the pond edges to JNCC have outlined common standards of monitor- attract females; provided that the water is clear ing, to ensure that monitoring methods, timing and not covered with floating vegetation, a walk and duration are comparable across all areas desig- around the pond counting all newts seen will pro- nated for their amphibian fauna. These can be vide an estimate of abundance. It is also possible to found at http://www.jncc.gov.uk/csm/guidance/. count different species and sexes, although you It should be noted that both Natterjack Toads cannot distinguish between Smooth and Palmate and Great Crested Newts are highly protected spe- Newt Triturus helveticus females without catching cies in Great Britain (see Section 22.3 below) and a them. licence is required from the relevant government Torch counts are useful for estimating breeding agency to survey for them. In Northern Ireland, a populations, but it should be borne in mind that, licence may be required to survey for Smooth Newt for territory-holding species, if numbers are high, Triturus vulgaris. some animals may not be holding territories and so Table 22.1. Methods for surveying and monitoring amphibians

Recom- mended species Population Other Expertise group size data attributes Efficiency Precision Bias required Advantages Disadvantages

Torch All Presence Sex ratio Good if water Low Under- Identification Quick method Will not detect counts Index (night is clear estimate for assessing all individuals Estimate counts) presence Bottle Newts Presence Sex ratio Requires Low Under- Identification Many animals Will not detect traps Index several estimate b Handling can be caught all individuals Estimate a visits with minimum Tends not to effort catch juveniles Netting Newts Presence Sex ratio Good for Low Under- Identification Quick and Will not detect Anuran Index presence in estimate Handling simple capture all individuals tadpoles Estimate a small ponds method Causes Poor for disturbance to estimation pond Pitfall All Presence Sex ratio Labour-intensive: Good (if None Identification Possible to Requires long traps Index Population traps must be traps are in theory Handling catch most intensive Estimate structure checked at least in place Construction animals sampling period Age ratio every morning long returning to and construction enough) pond of fence Expensive

Terrestrial Frogs Presence Sex ratio Can be time- Generally Under- Identification Estimates Counting transect Toads Index consuming if low estimate numbers dispersed searches large areas are outside ponds animals requires searched a wide search area; method is less efficient 389 Does not estimate numbers (except for frogs and Natterjacks ) Requires several trapping occasions Analysis can be complex methodology Can provide most accurate, unbiased results Expertise required Advantages Disadvantages Identification Simple Identification Photography (or other method) Data analysis Count varies by time of survey Low if correct model is applied Reasonable if spawn clumps or strings can be distinguished Good if assumptions are met and trapping effort is sufficient Good for small ponds Requires several trapping occasions and data analysis can be time-consuming Occurrence of breeding Emigration Immigration Recruitment Population structure Other attributes Efficiency Precision Bias Estimate (frogs and Natterjacks) Population size data .) cont All Presence All Estimate Survival Recom- mended species group ( If combined with a mark–recapture study. Unless combined with a mark–recapture study. Table 22.1. a b Egg searches Mark– recapture

390 22.2 General methods 391

Table 22.2. English Nature requirements for Great Crested Newt surveys

Number of Great Crested Newt visits per Survey aim Methods method Timing

Presence–absence (Pond) Three of these four methods: 4 Mid-March to mid-June, * bottle trapping; with at least 2 visits * torch survey; mid-April to mid-May * egg searching; * netting.

Presence–absence Transects, search by hand (preferably 60 March–October (Terrestrial) include pitfall trapping and drift netting) Population size class Bottle trapping or torch survey. 6 Mid-March to mid-June, assessment with at least 3 visits mid-April to mid-May

may not be counted. For Natterjack Toads, count- found that night counts of toads in different ing the number of croaking males can be used to ponds found between 5% and 50% of the total popu- estimate numbers, but it is possible that the pre- lation, as estimated by mark–recapture studies. sence of the surveyor will cause the males to stop Differences in the percentage of the total popula- calling, and in any case they can be difficult to tion confirmed by torch counts will be site-specific. pinpoint, making counts potentially inaccurate. Therefore, although torch counts are valuable for The torch count method will generally under- determining presence and suggesting abundance, estimate total population size but will give a useful comparison of counts from pond to pond requires index of breeding population size, and is one of the an assessment of sampling efficiency. quickest and easiest methods for establishing presence or absence of a species in a particular pond. Field methods Several counts will need to be made, possibly com- When surveying ponds, the simplest method is to bined with other survey methods such as bottle start at one point and walk slowly around the pond, traps (Section 22.2.2), before an absence can be scanning the water with a torch. If the water is taken as confirmed; on the other hand, it only fairly opaque, or if aquatic plants are common, it takes one sighting to confirm presence. may be necessary to stop and scan the pond care- Torch count surveys can provide census data for fully at regular intervals. A count is made of each annual monitoring. However, they need to be used species. For newts, distinguishing the sexes is rea- with caution. For the data to be truly effective, a sonably straightforward; numbers of males and site should be visited several times during the females can be counted to obtain an estimate of breeding season to ensure that the count rep- the sex ratio. This is not straightforward for toads resents the peak number of animals. When com- and frogs; single males and pairs should be counted paring counts from different populations the ease (single females are very rare). of making the count must be taken into account. The site should be surveyed at similar times on Highly turbid water, inaccessible areas of bank, more than one date. It should be noted that the and weather conditions will influence the count behaviour of amphibians is strongly influenced by and make comparisons difficult. Latham (1997) weather: they are more active during wet and 392 22 AMPHIBIANS

warm conditions. Survey times should take When several ponds in a site are being surveyed, a account of this, and surveys should be carried out percentage of occupied ponds can be calculated. during a range of different conditions. If numbers are being counted, a graph can be If counts from different surveys are to be aver- plotted of numbers against date to obtain an idea of aged or otherwise compared, care should be taken the change in numbers over the course of a breed- to standardise the survey methods; each visit to one ing season. pond should be the same length of time. Obviously, Care should be taken when looking at changes in larger ponds will take longer to survey, but as long count data over the course of one year. Newt num- as all visits to one pond are of the same duration, bers will drop off during the spring–summer period data for that pond over time can reasonably be com- as individuals breed, lay eggs and leave the pond. For pared. Another method of standardisation to allow Great Crested Newts, which tend to breed in ephem- comparisons between different populations is to eral ponds, numbers will also go down as the ponds divide the bank into 2 m segments and express dry out. It is therefore best to restrict sampling to counts as number of animals per 2 m length of bank. early in the breeding season, when the greatest When surveying frogs and toads with this number of animals will be present in the pond. method, it should be remembered that these two A classic flaw of many EIA surveys of amphibians groups are explosive breeders; numbers in a pond is that they are often carried out at the wrong time will rapidly reach a peak and will tail off soon after of year and provide little useful information. mating has occurred. This happens over a 2–3 week Torch count data for frogs and toads will gener- period. In order to obtain a maximum count, at ally be from a much shorter time period than for least five counts will be needed to ensure that the newts, because their mating and egg-laying period is peak is captured. This requires some prediction of shorter. However, it is feasible to treat torch count when the population will move to the pond. By data as an estimate of total breeding population watching roads and paths close to the pond, it rather than an index if the count period includes should be possible to notice when large numbers the peak of animals in the pond. The peak count of of frogs or toads are active, and you can start counts males can be converted into an estimate of total after this has been observed. A night temperature adult male population (Halley et al., 1996)bymulti- of over 6 8C combined with damp conditions will plying by 2.5. This multiplier is based on detailed produce a rapid movement. As a rule, it takes five mark–recapture studies. The sex ratio can also be days from the time of the first animals reaching the estimated from the proportions of the two sexes pond until the peak of toad numbers is reached. caught in pitfall traps (Section 22.2.4). Frogs are often quicker breeders, and can be in and For longer-term monitoring, peak torch counts out of ponds in a matter of days. They are also more in each year can be compared to ascertain popula- elusive, so torch counts are less reliable for frogs tion trends. Potentially, these can be analysed by than for toads and newts. using methods such as regression. If a sample of When surveying at night, safety precautions ponds has been studied, statistical tests may be must be taken. Surveyors should work in pairs useful to compare ponds and made even more use- and carry mobile phones or two-way radios. ful if habitat and physical characteristics data are Working on slippery pond edges in darkness is collected (Part I, Section 2.6.4). Application of these particularly hazardous. Monitoring amphibians by methods will depend on effective standardisation torch counts has very simple equipment require- of fieldwork. ments (Appendix 6). 22.2.4 Bottle traps Data analysis and interpretation Data analysis will depend on the type of survey Principles being carried out. If ponds are merely being sur- Bottle trapping is a useful method of trapping veyed for presence–absence, analysis is restricted. newts in ponds for simple counts or for 22.2 General methods 393

1) Cut bottle in two roughly 1/3 of the length from the top

2) Turn bottle top around and insert into other section

3) Cut air holes in end and holes for rod at front

4) Push rod through holes at entrance to secure trap. The rod should fit firmly so that the trap cannot easily slide up and down

Figure 22.1. Construction of bottle traps. Note that the rod should be longer than shown here. Traps without air holes may also be required if the traps must be completely submerged. mark–recapture studies. Bottle traps are designed is limited; traps must therefore not be left to ensure that newts can easily enter them but unchecked for more than a few hours, especially cannot easily leave. They are best used during the in warmer weather. Submerged traps, which do not breeding season when newts are engaging in breed- allow breathing, must not be left unchecked longer ing behaviour, but can also be used for trapping than 12 hours in March and April, 10 hours in May, larvae (of newts and other species) later in the year. 8 hours in June, 7 hours in July and August, and 8 Peak bottle catches of adult newts are obtained in hours in September (see, for example, SNH Great March–April when activity is greatest at the start of Crested Newt survey licence guidelines). They must courtship (Oldham, 1994). Metamorphs emerge in be held firmly in place to prevent tilting and loss of late summer and early autumn, so trapping at the the air bubble. Traps that allow air breathing must start of this period will yield the greatest number of not be left unchecked longer than 17 hours over- metamorphs. night and should be checked between 06.00 and Bottle trapping is the best method for ponds that 11.00 hours. It is generally recommended that are heavily vegetated, making netting and torching traps with air holes are placed around the edges difficult. of the pond with the trap entrances facing towards deeper water and the bottom of the trap resting on Field methods the pond substrate (Figure 22.2). Trap construction It should be remembered that water levels can Bottle traps can be cheaply constructed from 2l fluctuate considerably in ponds, particularly if it is plastic drink bottles and thin garden bamboo raining. It is therefore important to have a long canes or dowel rods (see Figure 22.1). It is recom- length of rod sticking out of the water so that the mended that the rods be painted white to enable traps can still be pinpointed if the water level rises. them to be found again more easily. This is especially useful if the pond water is cloudy. There is a risk that newts will drown if water Trap placement levels rise to the extent at which traps with air Bottle traps can be placed either around the pond holes are completely under water. If it is known edges or deeper in the centre of the pond. In the that water levels are likely to rise during a trapping latter case, the oxygen supply for trapped animals occasion, the traps can be attached to bricks with 394 22 AMPHIBIANS

Rod sticking out of water so caught, data are best treated as a population that traps can be easily found index. In addition, although there is no evidence Air holes to allow breathing that Smooth or Palmate Newts show a trap response, a bias towards males is normally observed, but not for Great Crested Newts Trap entrance (Griffiths & Inns, 1998). An index can be derived touching pond from numbers trapped per unit effort (number of substrate days and number of traps). The number of newts Rod pushed firmly into ground caught will be roughly proportional to the number of traps used; if trapping is standardised to one Figure 22.2. Placing bottle traps trap per 2 m length of shoreline, the total catch will be between 2% and 28% of the population on any one night at the peak of the mating season string and floated on the water surface; the slack in (Griffiths & Raper, 1994). Statistical tests to compare the string will prevent the trap from being totally years or to look for trends may be applicable (Part I, submerged. Section 2.6.4). The traps are placed at regular intervals around It is recommended that, in order to obtain the the pond, usually at intervals of 1–2 m. Place the best estimates of population size, bottle trapping traps just before dusk, and return to check them be used as the basis for mark–recapture studies; the early in the morning. If trapping during warm extra time involved in marking and identifying weather, do not place so many traps that some individuals will provide a much clearer and more will not be checked until late morning; there is a accurate estimate of population size, as well as risk of mortality if trapped newts are exposed to enabling other population parameters to be esti- heat. mated. See Section 22.2.7 for further details. Bottle catches are affected by several variables, including weather, trap spacing and the stage of 22.2.5 Netting the breeding season. The peak in breeding activity will be influenced by the geography of the site, so it Principles is recommended that trapping be done in March, Netting animals in ponds is a relatively quick and April and May (March may be too early in some simple method of catching amphibians, provided years, depending on temperature). Trapping dur- the pond is small enough; larger, deeper ponds ation should be three blocks of a minimum of may require waders and other safety equipment. three consecutive days. This method should, however, be carried out spar- Appendix 6 outlines the field equipment neces- ingly, especially in small ponds, because consider- sary for surveying and monitoring with bottle traps. able disturbance is caused to both the pond and its wildlife. Data analysis and interpretation Netting is probably most useful for checking the If newts are being captured for a mark–recapture development of amphibian larvae and thus gaining study, refer to Section 22.2.7 for details of methods an idea of breeding success. Estimates of adult for marking or otherwise recording individual ani- population size cannot realistically be achieved mals and subsequent data analysis. with this method; the disturbance caused by net- If trapping data are not to be used for mark– ting will frighten animals away and make them recapture studies, then a simple calculation of harder to catch. Netting will therefore only catch mean number of animals caught per trapping occa- a small percentage of animals in a pond unless sion can be calculated for each breeding season. carried out intensively, but this is not However, as it is unlikely that all newts will be recommended. 22.2 General methods 395

Field methods adjacent to the fence line. Most species of amphi- A sweep net should have a solid frame, as weaker bian can be caught by using this method, although heads cannot usually cope with the vegetation and frogs can often jump out of the traps if they are too debris encountered. The net is raked through the shallow. water along the bottom of the pond. When the net If a pond is surrounded by fencing and traps is removed from the pond, the debris caught in the before the animals emerge from hibernation, it is net is sifted for amphibians. Be sure to return any possible to catch most animals as they return to the other species caught to the pond as soon as possi- pond (assuming that the fence is secure) and thus ble, and place any amphibians in a holding tank for make a reasonably accurate and unbiased assess- identification and counting. The field equipment ment of the population entering that particular required for monitoring by sweep netting is sum- pond, provided that the traps are left in place for marised in Appendix 6. a sufficient length of time. In practice there may Try not to leave amphibian larvae in tanks for well be some animals that overwinter in the pond too long before release; most species are carnivor- itself, or a part of the fence that some animals may ous at this stage, and may predate each other. penetrate, but pitfall trapping does provide a good If you are attempting to do more than just estimate of the population of a pond when applied confirm presence or successful recruitment of in this manner. juveniles, the netting methodology must be Fences are at best 80% effective unless con- standardised to ensure that data are comparable structed as permanent structures. If traps are between sites and visits. As an example, one installed on both sides of the fence, estimates can sweep at each 5 m interval around the pond edge, also be made of the number of adults and meta- or five sweeps at three set points per visit, could be morphs leaving the pond, and thus breeding suc- used as a standard. cess and recruitment can also be measured. Trap design will need to take account of species and life Data analysis and interpretation history; traps for adults are not necessarily suitable for metamorphs because of the size difference. Netting data are usually used to confirm presence Traps and fencing can also be constructed in of animals in a pond, particularly of larvae. If the terrestrial amphibian habitats. In this case, the netting method has been standardised, numbers fence is built in a straight line, and serves to direct caught at different times (within or between any animals encountering the fence into the traps. years) can be treated as an index of population This will trap a greater number of animals than and compared over time, although relating this would be caught by using traps alone. index to actual population size is not practicable. A further use of traps is to construct a trapping Data can potentially be analysed statistically by web (Section 10.9), which can be used to estimate using standard tests (Part I, Section 2.6.4). density. However, the most common use of pitfall traps when monitoring amphibian populations is 22.2.6 Pitfall traps to install them around ponds to obtain estimates of the breeding population or a population index. Principles Pitfall traps are constructed around breeding ponds Field methods or hibernacula or across routes that amphibians Drift fencing must be constructed to prevent ani- are likely to traverse, in conjunction with drift fen- mals from climbing over, through or under it. The cing. An amphibian encountering fencing will tra- fence consists of black polythene sheeting (1000 vel along the fence trying to find a way around (the gauge is recommended) of 750 mm width, stapled usual movement is a zigzag pattern along the to wooden stakes 38 mm Â 38 mm Â 850 mm fence). It then has a chance of falling into one of (other types of polythene can be used; lighter the pitfall traps, which are situated immediately sheeting is cheaper but is more likely to tear). 396 22 AMPHIBIANS

(a) Black polythene sheet (1000 gauge) x x 150 mm folded twice

500 mm Wooden stakes x 38 mm × 38 mm × 850 mm x Staples 600 mm

x 260 mm x

250 mm 100 mm 10 litre bucket with snap-on lid flush with ground level

Wooden stake

(b)

Polythene fence Staples on this side Bucket with edge flush against polythene

Figure 22.3. Construction of pitfall traps and fencing. (a) Front elevation; (b) plan view.

The sheeting is buried to a depth of 100 mm and Thestakesshouldbeonthesideawayfromthe should be 600 mm tall, with the last 150 mm folded traps, unless traps are to be placed on both sides of over at the top. The traps are usually 10-litre the fence. buckets, with snap-on lids. These are buried flush When digging out the fence line it is usually with the ground and with the fence line. The easiest to dig a fairly wide, deep trench; this makes stakes should be 0.5–1.0 m apart. Distance placing the stakes and sheeting more straightfor- between traps must be kept standard so that sam- ward and allows you to curl the bottom of the sheet- plingeffortiskeptconsistent;onetrapevery10m ing away from the stakes, providing a greater barrier should be sufficient. For smaller ponds, traps can to any animals that may attempt to burrow under. be placed closer together. Details of fence con- The trench must be backfilled and compacted, so struction and trap placement are shown in that there are no cracks or gaps that might enable Figure 22.2. The buried lip prevents animals from animals to burrow down alongside the fence. burrowing under the fence, and the rolled-over lip The sheeting can be attached to the posts with at the top prevents animals from climbing over. two 14 mm staples placed through a 25 mm Â 25 mm 22.2 General methods 397

plastic or plastic-coated washer at the top, middle the fence and traps must be left up until trapping and bottom of the fence. A quicker method is simply effort outstrips the number of animals captured. If to use one staple at each point, put in with a staple you are trapping for a mark–recapture study, the gun. The sheeting should be taut and should not traps can be removed once it is considered that a have any creases; amphibians, particularly newts, reasonable proportion of the estimated population are capable climbers and could potentially scale the has been caught. fence by means of diagonal or vertical creases in the When pitfall trapping frogs or toads, you should sheeting. be prepared to catch a large number of animals; it is The traps should be flush with the ground and not unusual to catch as many as 80 toads in a single the fence; if the traps are raised above the ground, trap, and populations can be in the thousands in animals turn back at the lip, whereas if the traps good ponds. Frog populations are generally smaller are not tight against the fence animals might be but may be caught in a short space of time. Traps able to walk between the lip of the trap and the for frogs need to be adapted; they can jump out fence without falling in. from 10-litre buckets. They are less likely to escape Put some leaves or grass into the traps as cover from wet traps (i.e. traps with water at the bottom), for any animals that are caught, otherwise there is but to make a trap fully escape-proof a cage needs a risk of predation from birds or other animals. to be constructed over the trap. The field equip- Also make sure that the plant material is kept ment requirements for surveying and monitoring damp. Some small holes should be pierced at the by pitfall trapping are listed in Appendix 6. bottom of the traps to allow water to drain away if it rains during the trapping period, unless the Data analysis and interpretation ground is permanently boggy or waterlogged. If When trapping around a pond, if you are certain the traps are prone to flooding, bark or wood that the traps were set up before any individuals ‘islands’ should be placed in the trap to reduce reached the pond and were not taken down until the risk of animals drowning. no more animals remained to be caught, the total If it is likely that small mammals may be captured, number of animals trapped can in theory be taken especially shrews, ‘mammal ladders’ must be pro- as the exact number of animals breeding in the vided in the traps (Griffiths & Inns, 1998)orasep- pond. In practice, there will be some inaccuracy arate trapping licence must be obtained. Mammal as animals may overwinter in ponds, breach the ladders are commonly narrow strips of wood or fence, or arrive late to the pond, but this never- thick rough stems that reach from the middle of theless remains a good and accurate (although the trap bottom to the top. It should be remembered expensive and time-consuming) method of assess- that these will also allow the escape of some of the ing population size. target species, which will bias results downwards. Trapping for a set number of days each year will The traps should be checked daily while in place, yield a population index, which over time can be and should be visited as early as possible in the examined for trends by using methods such as morning. Search the litter in the trap very carefully; regression (Part I, Section 2.6.4). newts will play dead when disturbed, and it is easy Another use of pitfall trap data is in conjunction to overlook individuals, particularly small juveniles. with a mark–recapture study (Section 22.2.7). This If trapping around a pond, place trapped animals combination has the advantage that trapping dura- into the pond once they have been counted, photo- tion need not be constant from one year to the graphed, marked or otherwise recorded. If the traps next, as long as a reasonable proportion of the are not to be checked daily, the lids must be fitted population is caught each time. For further details between trapping periods to avoid the risk of of mark–recapture analysis and methods see trapped animals being eaten or starving. Sections 22.2.7 and 10.11. If trapping is being carried out with the inten- Trapping metamorphs leaving the pond is a tion of trapping all animals returning to a pond, good way of estimating the breeding success and 398 22 AMPHIBIANS

annual recruitment of a population. Oldham (1994) of the search, search times should be standardised describes a study that used pitfall traps on both for each habitat and for each visit. sides of a fence around a Great Crested Newt For newts, terrestrial searches are best con- pond for an entire year. This kind of intensive ducted during the day, and any suitable refugia monitoring enables detailed and accurate assess- should be investigated. Appendix 6 summarises ments to be made of population size and breeding the equipment required for surveying and moni- success, as well as providing information on the toring by using terrestrial transect searches. timing of movements of animals at different stages of the year. It is unlikely that a monitoring pro- Data analysis and interpretation gramme would be this intensive, but the data For details of how to analyse transect data, see gathered from such experiments is useful when Sections 10.6 and 10.7. It should be remembered designing monitoring schemes. when interpreting transect data that amphibian densities in terrestrial habitats will be lower than when 22.2.7 Terrestrial transect searches they are concentrated together in ponds. They are also much harder to find on land, which will tend to Principles bias results downwards. Standardising search effort Terrestrial transect searches are used to estimate between observers can also be problematic. amphibian numbers on land, as opposed to most Estimating abundance with transects is more other methods, which are based around pond problematic than estimating abundance at breed- searches. Transects of a standard length are ing sites. selected and are searched with consistent effort. This is not a suitable method for accurately estimating population size unless combined 22.2.8 Egg searches with a mark– recapture study (Section 22.2.7). Principles However, the number of animals detected per Egg searches are generally used to obtain evidence unit of person-hours provides an index of popula- of amphibian breeding. Amphibian eggs are tion size. usually easily recognisable, and can be attributed at least to frogs, toads or newts. Field methods Frog populations can be estimated from the Transects are searched by the surveyor carefully (i.e. number of spawn clumps; it is assumed that each on hands and knees) and cover objects within a female lays one clump, and that the sex ratio is specified distance of the line are searched for amphi- 1 : 1. Egg searching is an effective means of estab- bians, as are any traps that may have been placed lishing newt presence. However, egg laying is along the transect. For example, rocks and logs not uniform throughout the season, and it is should be turned over, because amphibians often therefore difficult to estimate newt population hide underneath them. If surveying at night with a size from egg counts. It is not possible to distin- torch, particularly in damp conditions, the animals guish between Smooth Newt and Palmate may be more mobile and can be seen more in the Newt eggs. open. In upland grassland or moorland habitats, Natterjack Toad spawn strings are relatively frogs can be more visible in daylight and it may be easy to identify given the shallow and ephemeral possible, in some cases, to index the population nature of the ponds used for breeding by this spe- while walking a transect during daylight hours. cies. This is a standard method for assessing the For anurans (frogs and toads), terrestrial number of breeding females. Common Toad searches should be conducted with torches during spawn strings are often harder to count as they the evening, after the breeding emigration from are often wrapped around aquatic vegetation and the pond. Although the habitat will affect the ease may be in fairly deep water. 22.2 General methods 399

Field methods Griffiths & Inns (1998). It has been found that Newts there is a good positive correlation between num- Newt eggs are laid singly in folds on aquatic vege- ber of spawn clumps and mat area, and a graph has tation; the egg is laid on the underside of the leaf, been produced that can be used to estimate the which is then folded over to protect the egg. With number of spawn clumps from spawn mat area practice, the folded leaves can be seen from the (roughly 80 clumps per square metre of spawn bank. Great Crested Newt eggs can be distin- mat). Untrained surveyors were considerably less guished from those of the two smaller native consistent in their estimates of spawn clumps, so newt species by their larger size and their colour: some degree of experience is necessary if precise they are about 2 mm in diameter, surrounded by a estimates of frog numbers are to be obtained. clear jelly capsule about 4.5 mm long, whereas Toad eggs are laid in long strings, and it is not smooth and palmate newt eggs are about 1.5 mm always easy to separate them into single strands. diameter in a 3 mm capsule (Buckley & Inns, Common Toads usually lay two parallel spawn 1998). strings; Natterjacks usually lay one string, but Egg sticks, which are strips of black polythene may spawn twice in one year. stapled to bamboo canes, can be placed in the pond Egg searches for Common Toads are therefore to provide extra laying sites. These can be more mainly used for determining presence and breeding, easily searched, and can be used to standardise although the number of breeding female Natterjack effort for each pond and each visit: a set number Toads can be assessed by counting spawn strings, can be placed in each pond, and these can be because they can usually be distinguished in the searched each time a visit is made. shallow ponds favoured by this species. Egg counts will reach a peak around May and Appendix 6 outlines the field equipment cannot easily be used for population size compari- required for surveying and monitoring amphibians sons unless the counts are made in each pond at the by using egg searches. same phase of the egg laying season (Oldham, 1994). Alternatively, if several counts are made at each Data analysis and interpretation pond over a period that includes the peak count, Egg searches are generally used to establish the pre- peak numbers can be compared between ponds. sence of amphibians. However, it is not possible to separate the smaller newt species by using this method. The use of egg counts to estimate numbers Frogs and toads is possible with frogs and natterjack toads as long as Frog spawn is laid in large globular clumps, and you are careful to count different ponds at the same one clump is laid by each female. These clumps time of the egg-laying season, and provided the peak float when freshly laid but sink to the bottom count is captured during the surveying period. after a few days. Consequently, if frog populations With standardisation of fieldwork, counts can are being estimated by counting clumps, several be compared over time or between ponds and stat- visits will need to be made to obtain a peak number istical tests may be applicable (Part I, Section 2.6.4). of spawn clumps. In good ponds, so much spawn can be laid that it 22.2.9 Mark–recapture studies forms a mat and it becomes hard to separate clumps. In this case, you can either sort through Principles the spawn by hand to separate and count the The principles of mark–recapture theory are dis- clumps (possible in smaller ponds), or make an cussed in Section 10.11. Essentially, animals are estimate of the surface area of the pond covered trapped by using one of the trapping methods by one clump and extrapolate this across the area described above, then marked in some way so covered in spawn. This method has been detailed that recaptures can be identified, and finally by Griffiths et al. (1996) and is summarised by released. Subsequent trapping will reveal the ratio 400 22 AMPHIBIANS

of recaptures to new captures, which is used to transparent box. Apply slight pressure to the back estimate total population size. of the sponge to hold the newt in place, and hold the Mark–recapture studies provide a population box up to take the photograph. With practice, each estimate together with a confidence interval and newt can be photographed in a very short space of are therefore the most effective method for popu- time and returned to the pond quickly, thus mini- lation studies. They also allow the estimation of mising disturbance. A purpose-built camera rig for other population parameters such as births, photographing newt bellies is described in Baker & deaths, immigration and emigration, provided a Gent (1998). suitable model is used. Remember to label each photograph individu- The type of mark chosen will depend upon the ally as it is taken with details of date, capture type of mark–recapture analysis that is to be used. point, sex of newt, etc. This is most easily done by Some methods require individual recognition, writing on sticky labels and fixing them to the out- whereas others only need batch marking (i.e. all side of the photography box. animals caught on one occasion are given the same mark). Again, see Section 10.11 for details, Skin staining: toads and also Baker & Gent (1998). Toads can be individually marked or batch marked Invasive marking methods should only be carried by using a dental ‘Panjet’ tattoo gun, which fires out by trained personnel; a Home Office licence ink at high speed. This can be used on the bellies of under the Animals (Scientific Procedure) Act 1986 toads (the bladder area should be avoided to pre- is usually required. A licence is also required, for vent internal damage) and produces a mark that example, from SNH to take and disturb protected will last for 18 months and can therefore be used species (e.g. Great Crested Newt), so two licences for two breeding seasons. Frogs’ skin is thinner, may be required, depending on the method used. and this method is therefore not suitable for frogs. This is an inexpensive method, and if used with care will not cause any injuries. If the mark– Field methods recapture study is to last longer than 18 months, a Marking amphibians for later identification can be more permanent method of marking will be done in several ways. The techniques most com- required. See Wisniewski et al. (1980, 1981) for a monly used are outlined below. It should be borne fuller discussion of Panjet marking. in mind that invasive marking methods such as skin staining and PIT (passive integrated transponder) tags require trained and licensed personnel. For more PIT tags: all amphibians details concerning licensing see Part I,Section2.4.3. PIT (passive integrated transponder) tags are small electronic tags, which generate a response to a Photography of belly patterns: Great Crested signal produced by a scanner. The tags are inserted Newts under the skin, and recaptures are ‘read’ with a Adult and sub-adult Great Crested Newts do not portable scanner, which identifies each tag (Fasola require marking, as they can be individually distin- et al., 1993) and allows individual recognition of a guished by the orange and black belly patterns. potentially large number of animals. This is a much Newts are photographed with a camera fitted with more invasive method of marking than Panjets, a macro lens, and photographs from different trap- and requires a Home Office licence. ping occasions compared to identify recaptures. PIT tags and scanners are expensive but are often To hold newts still while photographing them, cost-effective because of the amount of informa- use a transparent box such as a small computer disk tion they can provide an individual. They can be case and a piece of ordinary household sponge with obtained from Trovan, UK ID Systems Ltd, a newt-sized hole cut out. The newt is inserted Riverside Industrial Park, Preston, Lancashire PR3 gently into the hole, with its belly against the 0HP; Fish Eagle Co., Lechlade, Gloucestershire GL7 22.3 Amphibian conservation evaluation criteria 401

3QQ; and Labtrac Ltd, Holroyd Suite, Oak Hall, consider the status of the species at the local and Sheffield Park, Uckfield, East Sussex TN22 3QY. national scale. There are ongoing survey and moni- Different systems are not compatible. Another dis- toring programs for certain amphibian species. advantage of this method is that infections can English Nature holds a Natterjack Toad Site occur; this may increase the mortality of marked Register, which is updated annually, and monitors individuals and therefore bias the results. the status of the Natterjack Toad. For understand- Appendix 6 outlines the field equipment able reasons this is a confidential database, but required for marking amphibians. further information can be obtained from English Nature, Peterborough. Information about the local Data analysis and interpretation status of a species can sometimes be obtained from There is a considerable amount of literature the County Recorder or Biological Information devoted to the analysis of mark–recapture data; Centre (or BRC) or the local amphibian and reptile references are given in Section 10.11. group. Other sources of data are local Red Data It is important that the assumptions behind books, local amphibian atlases, and Local whichever model is chosen to estimate populations Biodiversity Action Plans. are fully understood and are met by the study. For example, the computer program CAPTURE Protection status in the UK and EU assumes that no animals enter or leave the population during the time of the study (i.e. a closed popu- Of the six amphibian species resident in the UK, lation). This assumption can be made if the study two (Great Crested Newt and Natterjack Toad) are takes place over a relatively short space of time, fully protected on Schedule 5 of the Wildlife & particularly early on in the breeding season. Countryside Act 1981 (as amended), which affords One of the advantages of compiling a capture them protection under Section 9. This makes it an history of individual animals is that data from one offence to: trapping occasion can be used in several different analyses. For example, trapping data from one * intentionally (or recklessly, in Scotland) kill, breeding season can be used to derive an estimate injure, take or possess these animals; of population size for that year. The same data can * intentionally or recklessly damage, destroy, also be used in a longer-term analysis in conjunc- obstruct access to any structure or place used by tion with data from other years to obtain not only a scheduled animal for shelter or protection, or population size estimates but also estimates of disturb any animal occupying such a structure or parameters such as recruitment and survival. place; Mark–recapture studies over one field season * sell, offer for sale, possess or transport for the can only be used for males of frog and toad species, purpose of sale (live or dead animal, part or deri- as the females will leave the pond after spawning vative) or advertise for buying or selling these and thus their residency in the pond is shorter. animals. Female population size can be derived from the Smooth or Common Newts are protected under sex ratio observed from pitfall trapping or breeding Schedules 5 and 7 of the Wildlife (Northern counts. Ireland) Order 1985. In Northern Ireland, the word ‘recklessly’ is not included in the legislation. 22.3 AMPHIBIAN CONSERVATION In addition, Great Crested Newt and Natterjack EVALUATION CRITERIA Toad are Schedule 2 species protected under Regulation 39 of the Conservation (Natural 22.3.1 Key evaluation considerations Habitats & c.) Regulations 1994 (as amended). As As previously stated, when considering the conser- such, in addition to the above offences, the vation value of a site or population it is necessary to Conservation Regulations make it an offence to 402 22 AMPHIBIANS

Table 22.3. NCC population size class assessment for different amphibian species

Count for low Count for good Count for exceptional Species Method of search population population population

Great Crested Newt Netted or seen (daytime) < 5 5–50 > 50 Night count < 10 10–100 > 100 Smooth Newt Netted or seen (daytime) < 10 10–100 > 100 Night count < 10 10–100 > 100 Palmate Newt Netted or seen (daytime) < 10 10–100 > 100 Night count < 10 10–100 > 100 Common Toad Estimated < 500 500–5000 > 5000 Counted < 100 100–1000 > 1000 Common Frog Spawn clumps counted < 50 50–500 > 500

Source: NCC (1989). damage or destroy a breeding site or resting place of available on the DEFRA website (http://www.defra. these species (not just intentionally, deliberately or gov.uk/environment/statistics/wildlife/index.htm, recklessly). Great Crested Newts are also listed on assessed in 2004). Annex II and Annex IV of the EU Habitats Directive; The Great Crested Newt is an IUCN Lower Risk/ Natterjack Toads are listed on Annex IV. They are Conservation dependent species (i.e. should conser- both UK Biodiversity Action Plan Species. In vation efforts cease, it would qualify for one of the Northern Ireland, the Wildlife (Northern Ireland) higher-risk categories within 5 years) (IUCN, 2003). Order 1985, the Nature Conservation and Amenity It is distributed across lowland Britain, being absent Lands (Northern Ireland) Order 1985 and the from parts of Wales and Scotland and parts of south- Conservation (Natural Habitats, etc.) Regulations west England (Beebee & Griffiths 2000), and is one 1995 replace the Wildlife & Countryside Act. of the more endangered species in the UK. It is Common Toads, Common Frogs, Palmate Newts not found in Northern Ireland. and Smooth Newts are all afforded protection The smooth newt is a common and ubiquitous against sale only under Schedule 5 of the Wildlife speciesintheUK,althoughitisrareinthe & Countryside Act 1981. Highlands, the far South West of England, and parts The status of the Pool Frog Rana lessonae in the UK of Wales (Beebee & Griffiths, 2000). Palmate Newts is uncertain; it may be a native species. There is a aremorepatchilydistributed across Britain, being UK Biodiversity Action Plan for the species, which rare across the Midlands, East Anglia and the aims to establish its status. Should it be deemed to Highlands, and are regarded as common. They are be native, it will likely become fully protected on not found in Northern Ireland (Beebee & Griffiths, Schedule 5 of the Wildlife & Countryside Act. It is 2000). listed on Annex IV of the EU Habitats Directive. The Natterjack Toad is mostly restricted to coastal All species may be Local BAP species depending sites in Britain, although there are a few remnant on their local distribution. populations on heathlands (Beebee & Griffiths, 2000). It is rare in the UK and is the subject of an Conservation status in the UK English Nature Species Recovery Programme (Beebee &Denton1996). Both Common Toad and Common The assessment of population status in the UK Frog are widespread and abundant in Britain (Beebee for each amphibian species is based on tables &Griffiths,2000) and are considered common. 22.3 Amphibian conservation evaluation criteria 403

Table 22.4. NCC scoring system for the selection of using the approach outlined in Chapter 3 of this potential SSSI sites Handbook (based on IEEM guidelines 2002); it would be difficult to give more precise selection Item Score criteria. The SSSI designation criteria, outlined in NCC Low population (per species) 1 (1989), can be used as a standard to assess whether Good population (per species) 2 sites are of national importance. All important and Exceptional population (per species) 3 established (i.e. viable population at the site for the Four species present 1 last five years) colonies of Natterjack Toad should Five species present 2 be considered of national importance. Important Natterjack Toads present 2 colonies are sites with more than 100 individuals or 25 spawn strings counted on site for two out of the Source: NCC (1989). preceeding five years, sites on heathland, or the As previously stated, the status of the Pool Frog best sites in that vice-county. is uncertain in the UK; native or not, it has a very For Great Crested Newts, any site that has con- restricted range, with possible remnant popula- tained an ‘exceptional’ population for the previous tions in Norfolk, Northamptonshire and three years is eligible for designation as a SSSI Cambridgeshire. It may even be extinct and is (Table 22.3). In addition, there is a scoring system part of an English Nature Species Recovery (NCC, 1989) to identify ‘outstanding assemblages’, programme. as shown in Table 22.4. Sites qualify if they score a Natterjack Toad, Common Frog and all newt spe- minimum of ten points, with a species assemblage cies are thought to be in decline in Britain (Beebee & of at least four species. Griffiths, 2000); amphibian populations are thought A site is considered to be of County importance if to be in decline globally (Gardner, 2001). it contains a regularly occurring locally significant population of a Local Biodiversity Action Plan species or species listed in the County Red Data Book. Site designation criteria For levels of importance below this, please refer Sites of international importance for their amphi- to Part I as more specific guidance cannot be given bianfauna(i.e.candidateSACs)canbeassessedby here. 23 * Reptiles

Reptile surveying and monitoring can be proble- easily confused, unless you are certain that the matic; reptiles are active, shy creatures, which do population is isolated. not aggregate for breeding as do amphibians. Their behaviour is also heavily influenced by the 23.2 GENERAL METHODS weather. Most methods for surveying and monitoring reptiles do not generally produce sufficient A survey for reptiles should start with an assessment data to enable population size to be estimated, of the habitat suitability for different species, to unless mark–recapture techniques are used. establish which, if any, reptiles are likely to occur in the area. For example, Grass Snakes Natrix natrix are more likely to occur in areas with freshwater 23.1 ATTRIBUTES FOR ASSESSING bodies; a summary of the habitat requirements of CONDITION the different species can be found in Gent & Gibson 23.1.1 Population size (1998). For establishing the presence–absence and approximate abundance of reptiles on a site, the Estimates of population size for reptiles are made most commonly used methods are a combination during April–October. Most methods for estimat- of walked transects and placing of artificial ing total population size employ mark–recapture refugia, as outlined below. A standard number of 7 studies. Population indices can be obtained with- survey visits is recommended to establish presence– out mark–recapture work, but results are less absence, 15–20 to estimate population size, ensuring accurate. that visits occur at the appropriate time of year, in suitable weather. The general methods available for 23.1.2 Breeding success surveying and monitoring reptiles are summarised in Table 23.1. Whether or not reptiles are breeding successfully For designated sites (i.e. ASSIs, SSSIs, SACs) the can generally only be ascertained by counting the JNCC have outlined common standards monitor- number of young animals entering the breeding ing, to ensure that monitoring methods, timing population each year. and duration are comparable across all areas designated for their reptile fauna. These can be found at 23.1.3 Survival and mortality http://www.jncc.gov.uk/csm/guidance/. It should be noted that a licence from the appro- Estimates of survival and mortality can only reli- priate statutory body is required to survey for Sand ably be made by mark–recapture studies; the survi- Lizards Lacerta agilis and Smooth Snakes Coronella val of individually marked animals from one austriaca, and should be obtained when surveying trapping occasion to the next can be estimated. in areas where these are likely to occur. Adders Unless dead animals are found, it is not usually Vipera berus are the only venomous snake in the possible to distinguish between mortality and emi- UK; although bites are rare, care should be taken gration. Similarly, immigration and births can be in areas where they are likely to occur.

# RPS Group plc and Scottish Natural Heritage 2005. Table 23.1. Methods for surveying and monitoring reptiles

Recommended Population Other Expertise species group size data attributes Efficiency Precision Bias required Advantages Disadvantages

Artificial All Presence Density Reasonable Affected by Handling Most species Expensive outlay refugia Estimate Survival ratesa weather Identification can be found to purchase either under, sheets at start or basking of study on, sheets Can be easily Requires time standardised and effort to between sites lay out sheets Standard walk All except Presence None Low Generally low Affected by Identification No expensive Number of transects Slow-worms Index weather equipment animals seen is required generally small Trapping All Presence Survival b Reas onable Hand ling Good way Traps must be Estimate Identification of trapping regularly Trap construction animals for checked and mark–recapture maintained studies Mark–recapture All Estimate Survival rates Depends on Good if None in theory; Handling Obtains best Time-consuming method of large numbers small, fast-moving Identification estimate of capture caught animals may Marking (licence population size not be caught may be required)

a If combined with a mark–recapture study. b Unless combined with a mark–recapture study. 405 406 23 REPTILES

23.2.1 Artificial refugia Principles Reptiles are often found underneath refuges such as logs. Slow-worms Anguis fragilis in particular are commonly found in this manner, but the other lizard and snake species will also readily use such cover. Putting down artificial refugia, such as sheets of metal or roofing felt, will encourage reptiles to shelter underneath them. The sheets are periodically turned over, and any reptiles underneath them are identified and counted. If the sheets are laid out in a grid, estimates of density 37 sheets in total Each sheet is 10 m from its neighbours as well as presence can be made. The sheets will Covers 0.29 ha and fits into 60 × 60 m area. often also be used by both Sand and Common Lizards Lacerta vivipara as basking sites. Figure 23.1. Grid pattern for artificial refugia. See text The advantage of this method is that refuges for details. can be spaced out systematically and added to areas where searching natural cover for reptiles can be surveyed by using multiples of the basic would be time-consuming. The distance walked 37-refuge array. between refuges can also be treated as a transect To check the refuge (reptiles can bask either on (Section 23.2.2) for recording purposes. Refuges or under refuges), gently lift one edge of the tin or should be hidden from plain view, as reptiles felt and watch for any reptiles; if they are present, under them are vulnerable to disturbance and allow them to move off before replacing the refuge collection by unauthorised people. (Froglife, 1999). In areas where adders may be pre- The numbers of reptiles found will vary depend- sent, use thick gloves when lifting refuges, and ing on the prevailing weather conditions, and this wear high boots or gaiters. should be taken into account when comparing The best time of year to set up the refuges is during results. the winter, so that they are in place before the reptiles emerge from hibernation in the spring. Placing refuges after reptiles have emerged may result in a Field methods period in which they will be undiscovered, and thus Reading (1996) proposes a standard survey metho- bias the results downwards. In many EIA studies, dology for reptile surveys. Refuges should be made however, the refugia may have to be placed out from 76 cm Â 65 cm rectangles of galvanised, cor- only a short time before the survey period begins. rugated sheet steel, painted black (e.g. with In order to encounter at least 90% of the reptiles Hammerite paint) on the upper surface to increase present, and determine the approximate population heat absorption on cool days. The standard survey size, the arrays should be visited and checked 15–20 involves a basic hexagonal array of 37 sheets times during the period from April to October. spaced 10 m apart in a grid pattern of 4, 5, 6, 7, 6, The best months of the year for finding most reptiles 5, 4 on the survey area. This covers 0.29 ha and fits are April, May and September, although they may into an area 60 m Â 60 m with the middle refuge at be found during all months between March the centre of a circle with radius 30 m (Figure 23.1). and October. Effort should be concentrated on the Alternatively, a rough rule of thumb is 5–10 refuges best months (Gent & Gibson, 1998). To determine per hectare (Froglife, 1999). Refuges should be presence–absence, seven visits are recommended, placed horizontally and as close to the ground as again in suitable weather conditions at an appropri- possible, although not on bare ground. Larger areas ate time of year (Froglife, 1999). 23.2 General methods 407

The most suitable weather conditions for find- that may be due to these factors can be identified ing reptiles will vary depending on which species and eliminated by only comparing results from are present. In general, reptiles are not easily found surveys undertaken during similar conditions. during very hot, dry weather or during very cold, Care should be taken when extrapolating results wet weather. The best conditions to find most spe- across a wider area. It might be possible that the cies occur during warm days (11–19 8C) with inter- refuges attract reptiles in from the surrounding mittent sunshine following cool nights with little habitat, thus increasing counts in the survey area. or no rain. The best time for surveying is between This could occur in areas in which available natural 09.00 and 11.00 hours, and 16.00 and 19.00. cover for reptiles is limited. When placing arrays to estimate population size, you should avoid choosing areas that look 23.2.2 Standard walk transects good for reptiles; this will give an upwardly biased result if you attempt to extrapolate results across a Principles wider area. Ideally, array locations should be ran- Transects can be used for reptiles that commonly domly or systematically located. However, sam- bask during sunny periods. They are effective for pling in areas that are obviously unsuitable (e.g. all reptile species except Slow-worms. A transect is large expanses of closely grazed or mown grassland selected and walked, and all reptiles seen are iden- or the middle of dense conifer plantations) will be tified and recorded. Transects can be combined a waste of effort. Some form of stratification with other survey methods (particularly artificial will usually be required at most sites (see Part I, refugia; see Section 23.2.1) and are generally the Section 2.3.3). most effective way of surveying Grass Snake, The sheets should be well hidden in the vegeta- Common Lizard and Sand Lizard, which are found tion but still exposed to the sun, and should be less often under refugia. numbered and labelled. It is recommended that Transects can be simply walked, or they can be they be removed at the end of the survey and more intensively searched by examining cover should not remain in one place for more than within a specified distance of the transect line, three seasons. Sheets should also be removed or which will increase the number of individuals found. relocated if it is suspected that they are being dis- This method requires a degree of competence turbed by people not involved in the survey work and experience, and it is advisable that surveyors (Griffiths & Inns, 1998). A summary of the field visit the site with an experienced herpetologist equipment required for surveying and monitoring before starting surveys. reptiles with artificial refugia is given in Appendix 6. Field methods Data analysis and interpretation Reptile transects are conducted in a similar man- Abundance and density can be calculated from ner to amphibian transects (Section 22.2.5). They counts made under refuge arrays. It is obviously can also be conducted as part of a survey involving important that survey methodology should be stan- a refuge array (Section 23.2.1). dardised so that counts can be compared between Reptiles are not easy to spot; you should walk areas and sampling occasions. slowly, with your back to the sun, concentrating on Counts or densities from different years can, likely basking spots outside the area of shadow and potentially, be analysed statistically by using stan- as far ahead as possible. Most reptiles are easily dis- dard tests (Part I, Section 2.6.4). It should be remem- turbed and will flee if you approach to within a few bered that variations may be due to differences in metres but will often return to their basking spot (or weather conditions at the time of survey rather nearby) within a few minutes if you retreat and than to an actual change in reptile numbers. It is remain still. Close focusing binoculars are useful. generally a good idea to record variables such as Searching should concentrate on suitable fea- temperature and wind speed, so that any variation tures; lizards will bask on log piles, stumps, the 408 23 REPTILES

base of dry-stone walls, discrete open patches of standardisation and sampling is used (Part I, ground among heather, fence posts, etc. and these Section 2.6.4). A rule of thumb suggests that only should be examined carefully. Snakes are often seen one fifth to one third of the total population will be on habitat edges or shaded from direct sunlight observed on a transect even during optimum con- under bushes or shrubs. ditions (Gent, 1994). Reptiles need to spend a lot of time basking Transect walks may be used for censusing adult when the sun is out but the air temperature is and juvenile populations. Recording the number of low. April, May and September are suggested as individuals provides a comparison for breeding the key months, with April and May having the success between years. advantage of being the breeding season when reptiles are more active and less wary. The best 23.2.3 Trapping weather conditions for surveying are temperatures between 10 8C and 17 8C with intermittent or hazy Principles sunshine and little or no wind (Griffiths & Inns, Reptiles can be trapped on land by using pitfall 1998). Surveys should be timed to coincide with traps and drift fencing. Reptiles encountering this temperature window, which will typically drift fencing will follow the fence line and fall occur between 09.00 and 11.00 hours and between into a pitfall trap. This method works best for 16.00 and 19.00 hours. small reptiles such as lizards. Traps, with or with- Common Lizards can usually be found when out fences, can be used to determine presence. the temperature exceeds 9 8C and the sun is out, Fences are useful for excluding animals from an and will bask in temperatures of up to 18 8C. area, but are probably not worth the effort for Monitoring should start at the beginning of surveying reptile populations. Traps are a less sui- March. Pregnant females will bask during June table method than transects or refuges as the day- and July; August and September are good times to time activity of reptiles leaves them vulnerable to look for hatchlings. predation and extremes of heat. Slow-worms are rarely seen in the open, although they do bask and have timings and tem- Field methods perature tolerances similar to those of the Pitfall (and fence) construction is covered in detail Common Lizard. Sand Lizards are more elusive in Section 22.2.4. than are Common Lizards and should be surveyed Traps for reptiles should generally be placed in starting in April and finishing with a hatchling warm, open areas, but covered (i.e. with a raised lid search in September. on legs) to provide shade to reduce stress to trapped Adders emerge relatively early from hiberna- animals. They should be repeatedly checked during tion, and will often bask together near their hiber- the day. Cover should also be provided in the traps nation site. Surveying can start at the beginning of to lessen the risk of any animals being predated or March. Adders bask in temperatures between 8 8C suffering from exposure. Animals should not be and 16 8C, and are less tolerant of higher tempera- left in the traps overnight, and the traps should tures than are other reptiles. Appendix 6 outlines be fitted with lids when not in use. the field equipment necessary for surveying and Traps should be placed in grids similar to those monitoring reptiles by standard transects. for artificial refugia (Section 23.2.1) or placed along habitat edges. The requirements for surveying and Data analysis and interpretation monitoring reptiles by using trapping techniques Measuring the amount of time spent can be used to in the field are outlined in Appendix 6. estimate abundance, expressed as sightings per hour. This can be used to compare sites, and esti- Data analysis and interpretation mates from different years can be analysed statisti- Trapping data are best used in conjunction with a cally by using standard tests provided appropriate mark–recapture study (Section 23.2.4); this allows 23.2 General methods 409

more precise estimates of abundance to be made, agency specialist should be sought before reptile as well as estimates of other population para- handling is undertaken. meters. Otherwise, straight comparisons can When catching reptiles by hand, take care to potentially be made between trapping data from avoid damaging the animals. Slow-worms should different occasions by using statistical tests (Part I, be held firmly but not tightly between the head and Section 2.6.3). However, because reptile densities body. Common Lizards should be caught by hold- are often low, the inherent variability of the data ing the whole of the head and body and supporting may make the identification of trends problematic. it in the hand. All lizards will drop their tails if Trapping effort should be standardised to allow badly handled, especially on warm days. This is comparisons to be made, and traps should be damaging, particularly for Slow Worms, which do sited in representative areas of habitat. not fully regrow their tails once lost. Lizards should therefore never be caught by their tails. If it is 23.2.4 Mark–recapture necessary to catch and handle Adders, particular care and caution should be exercised. Guidance on Principles recommended methods for the capture of Adders The principles of mark–recapture theory are dis- (including safety equipment) and other reptiles is cussed in Section 10.11. Essentially, animals are provided by Griffiths & Langton (1998). trapped by using one of the trapping methods Reptiles are not easy to handle and are very described above, marked in some way so that prone to damage. On first capture, reptiles will recaptures can be identified, and then released. writhe about, and snakes and Slow-worms may Subsequent trapping will reveal the ratio of recap- also defaecate. Adders should not be handled tures to new captures, which is used to estimate unless absolutely necessary. For lizards, it is very total population size. important that the surveyor does not panic and Mark–recapture studies will generally give the attempts to calm the animal by supporting it in most precise estimates of population size, and also the hand. Surveyors should also work in pairs in (providing a suitable model is used) allow the esti- case of Adder bites, which, although rarely fatal, mation of other population parameters such as can potentially be very serious. births, deaths, immigration and emigration. The type of mark chosen will depend upon the Marking type of mark–recapture analysis that is to be used. Marking methods are similar to those recom- Some methods require individual recognition, mended for amphibians (Section 22.2.7); PIT tags whereas others only need batch marking (i.e. all can be used. Reptiles can also be marked with paint animals caught on one occasion are given the (e.g. nail polish); this causes no damage, although same mark). Again, see Sections 10.11 and 22.2.9 the marks are only temporary and may make ani- for details. mals more at risk of predation. Reptile markings can be used to identify indivi- Field methods duals without the need for external or invasive Capture marks. Features that have been used include chin Reptiles can be caught for marking with spots for the Slow-worm and markings around the traps (Section 23.2.3) or by hand during tinning cloaca for the Common Lizard. Markings on the (Section 23.2.1) or transect (Section 23.2.2) surveys. head can be used for all snake species. In all cases, Catching reptiles by hand requires experience and markings can be drawn onto pre-prepared blank training, particularly for Adders, and is therefore sketches or photographed as the individual is held not recommended unless it is absolutely necessary in a transparent container similar to that used for for a monitoring programme. Handling of reptiles, Great Crested Newts (Section 22.2.7). Non-invasive particularly Adders, should only be undertaken by mark–recapture methods such as these should be trained personnel, and advice from an appropriate adopted in preference to others if possible to avoid 410 23 REPTILES

any adverse effects on reptile populations. The One species (Common Lizard) is fully protected field equipment needed for surveying and monitor- on Schedules 5 and 7 of the Wildlife (Northern ing reptiles by using mark–recapture techniques is Ireland) Order 1985. listed in Appendix 6. Smooth Snake and Sand Lizard are Schedule 2 species protected under Regulation 39 of the Data analysis and interpretation Conservation (Natural Habitats & c.) Regulations Details on the analysis of mark–recapture data are 1994 (as amended). As such, in addition to the provided in Sections 10.11 and 22.2.9. above offences, the Conservation Regulations make it an offence to damage or destroy a breeding 23.3 REPTILE CONSERVATION site or resting place of these species (not just inten- EVALUATION CRITERIA tionally, deliberately or recklessly). Smooth Snake and Sand Lizard are also listed on Annex IV of Key evaluation considerations the EU Habitats Directive, and Sand Lizards are a UK Biodiversity Action Plan Species. Slow-worm, As outlined in Part I of this Handbook, the status of Adder, Grass Snake and Common Lizard are the species at the local and national scale is an all afforded protection against killing, injuring important consideration when evaluating the con- or sale under Schedule 5 of the Wildlife & servation value of a site or population. The national Countryside Act 1981. status of reptile species is briefly outlined here, and All species of reptile may be Local BAP species, is reflected in the legal protection afforded to each depending on their regional status. species. Information about the local status of a species can sometimes be obtained from the County Recorder or Biological Information Centre (or BRC) Conservation status in the UK or the local amphibian and reptile group. Other The assessment of population status in the sources of data are local Red Data books and Local UK for each reptile species is based on tables avail- Biodiversity Action Plans. able on the DEFRA website (www.defra.gov.uk/ environment/statistics/wildlife/index.htm, assessed Protection status in the UK and EU in 2004). Within the UK, Common Lizards are considered Of the six reptile species resident in the UK, two common, and it is the most widespread reptile (Smooth Snake and Sand Lizard) are fully protected (Beebee & Griffiths, 2000). Sand Lizards are on Schedule 5 of the Wildlife & Countryside Act restricted to sites in Dorset, Merseyside and Surrey, 1981 (as amended), which affords them protection with recent reintroductions to an area in Scotland, under Section 9. This makes it an offence to: West Sussex and Wales (Beebee & Griffiths, 2000), * intentionally (or recklessly, in Scotland) kill, and are regarded as rare. The Smooth Snake has the injure, take or possess these animals; most restricted distribution of the UK reptiles, being * intentionally or recklessly damage, destroy, confined to Dorset, Hampshire and Surrey in obstruct access to any structure or place used by England (Beebee & Griffiths, 2000), and is considered a scheduled animal for shelter or protection, or rare. Slow-worms are widespread across Britain, disturb any animal occupying such a structure or but absent from Northern Ireland, and are locally place; common. Grass Snakes are widespread and locally * sell, offer for sale, possess or transport for the common in the south of England and parts of Wales, purpose of sale (live or dead animal, part or deri- but are uncommon in the north of England and vative) or advertise for buying or selling these largely absent form Scotland (Beebee & Griffiths, animals. 2000). 23.3 Reptile conservation evaluation criteria 411

Sites may be designated as SSSIs on the basis of Table 23.2. Population size class assessment for different their reptile fauna (NCC, 1989). All established reptile species populations of Smooth Snake or Sand Lizard qualify for consideration, with the exception of those Count for Count for Count for low good exceptional in Dorset, where the colonies have to be important Species population population population and established. Areas that contain at least three of the other species of reptile may be considered. Adder <5 5–10 >10 A similar framework to that developed by the Grass Snake <5 5–10 >10 NCC (1989) for amphibian site assessment has been Common <5 5–20 >20 created by Froglife for ‘Key Reptile’ Sites, based on Lizard the scoring system outlined in Table 23.2. A site Slow-worm <5 5–20 >20 should be considered if it supports three or more reptile species or two snake species, supports Source: Froglife (1999). an ‘exceptional’ population of a single species of reptile, or scores 4 or more points for its species assemblage (Table 23.2). In addition, consideration Adders have a widespread but patchy distribution should be taken of the local ecology, and sites in Britain, and are absent from Northern Ireland designated if they support a species particularly (Beebee & Griffiths, 2000). They are considered rare. scarce in the region. At the county level, site assessment should take Site designation criteria local abundance and distribution into account. AsiteisconsideredtobeofCountyimportance Sites of international importance for their reptile if it contains a regularly occurring locally significant fauna (i.e. candidate SACs) can be assessed by using population of a Local Biodiversity Action Plan spe- the approach described in chapter 3 of this Handbook cies, or species listed in the County Red Data Book. (based on IEEM 2002 guidelines); it would be diffi- For levels of importance below this, please refer cult to give more precise selection criteria. to Part I of this Handbook. 24 * Birds

Birds are highly mobile; although they are rela- approaches may involve relating bird numbers to tively conspicuous and easily identified, their food supply and distributioninrelation,forexample, populations are often difficult to estimate effec- to habitat loss or disturbance. tively. They are, none the less, the most intensively studied species group, and a large amount of data are available on the distribution, ecology and esti- 24.1 ATTRIBUTES FOR ASSESSING mated population sizes of most species. A substan- CONDITION tial network of experienced volunteers is involved 24.1.1 Population size in countrywide bird monitoring programmes such as the Breeding Bird Survey and the Wetland Birds Estimates of population size for most common Survey, organised by the British Trust for species, particularly the songbirds, are best made Ornithology (BTO) in the UK (the latter in associa- during the breeding season, when male birds are tion with the Wildfowl & Wetlands Trust, WWT). In most territorial and vocal. Although females tend some instances it may be possible to incorporate to be under-recorded, it may generally be assumed the information provided by these programmes that the number of males and females is broadly into a site-based monitoring scheme. equal. In other cases, the number of male ‘terri- The objectives of bird population assessment tories’ may be adopted as the unit of measurement. need to be clearly identified at the outset. Many species have a non-monogamous breeding Migratory birds may be winter or summer resi- system so the assumption of parity in the sexes is dents, or may only appear on passage between often a common flaw. In the winter, songbirds tend wintering and breeding grounds. Other species to be more elusive and their distribution more are resident all year round but may show seasonal clustered, making sample surveys difficult to variation in numbers owing to an influx of birds carry out. Winter counts are conducted principally from other areas during the summer or winter. for species that breed at low density in remote Autumn populations will also include birds that areas but concentrate in a few easily counted, dis- have fledged in that year (many of which will not crete areas (e.g. wildfowl and waders roosting at survive over winter). It is important, therefore, to high tide on estuaries, or raptors at communal be able to separate natural population cycles from roost sites). underlying trends in population size. Population estimates from similar times in each year should 24.1.2 Breeding success and productivity be compared, and it may be necessary to calculate 5 or 10 year means to remove ‘noise’ from the data. Methods of estimating breeding success vary For EIA studies the most critical factors are depending on the ease with which nests can be usually population size relative to other sites, found. It is important to be sure that nests that based on evaluation criteria, and the spatial distri- fail are no more or less difficult to find than nests bution of birds relative to the proposed location of that succeed. Observer impacts must also be the development footprint. More sophisticated avoided: there is evidence that observers can affect

# RPS Group plc and Scottish Natural Heritage 2005. 24.2 General methods 413

nesting success in a range of species. Breeding suc- Field methods cess is usually measured in terms of the number of independent young reared per nesting attempt. If the target is a very common and widespread Clutch sizes and daily survival rates of eggs and species or group of species, the method will inevit- chicks may also be calculated, providing an indica- ably require input from a large number of fieldwor- tion of the timing and possible causes of breeding kers. The Wetland Birds Survey (WeBS) a failure. partnership scheme of the BTO, WWT (Wildfowl & Wetlands Trust), RSPB (Royal Society for the Protection of Birds) and JNCC, uses a large volun- 24.1.3 Survival and mortality teer base and conducts counts on predetermined Estimates of survival and mortality usually require dates between September and March at most key that individuals be marked and recaptured, or sites for waterfowl (e.g. estuaries, gravel pit com- resighted, over reasonably long time periods plexes and reservoirs). Synchronising these counts (Section 10.9). Birds may be ringed, wing tagged helps to ensure that large movements of birds or dye marked. In each case, recoveries depend on between sites does not cause birds to be missed or the observer or a member of the public returning double-counted. The counts are also arranged to precise information on the location, date and iden- coincide with spring tides on most UK estuaries, tity of the bird. For some species, such as Whooper when birds are generally concentrated into small Cygnus cygnus and Bewick’s Swans C. columbianus, areas and local movement is minimal. Observers facial markings have been used to identify individ- record whether the accuracy of the count was influ- ual birds and ‘recoveries’ made by simply observ- enced by weather or visibility and whether they ing birds passing through sites each year. In each believe that the counts were an underestimate of case, the non-return of a bird to known sites the true figure for other reasons. implies mortality. Absolute counts are not confined to the winter, however; several schemes involve censusing breeding bird colonies, such as those of Grey Heron 24.2 GENERAL METHODS (Reynolds, 1979), and seabird species (e.g. Lloyd Table 24.1 outlines the general methods used for et al., 1991). surveying and monitoring birds in the field. Many single species counts are also undertaken as a means of tracking the population sizes of rarer species (for some of which further details are pro- 24.2.1 Total counts vided in Section 24.3). Principles For detailed information on carrying out seabird Direct counts are only practical for estimating the counts (and other seabird monitoring methods) see abundance of species when the whole population Walsh et al.(1995). can be located with confidence. This can include species that breed in distinct colonies, e.g. seabirds, Data analysis and interpretation Herons Ardea cinerea and Rooks Corvus frugilegus, It is best to be cautious when interpreting the reli- species that are large and conspicuous, e.g. swans ability of direct count data. For example, attempts and geese, and species that are ‘charismatic’ and at counting all breeding upland waders on a site confined to well-known fragments of habitat, will usually result in many being missed. Extensive e.g. Marsh Harriers Circus cyaneus breeding in reed population studies either have to guarantee a uni- beds or Slavonian Grebes Podiceps auritus breeding form effort in all areas of the species distribution, on lochs. Direct counts are also the most practical or effort at each site needs to be measured and a (although not entirely accurate) way to estimate note made of suitable breeding sites that are left populations of wintering waders or waterfowl on out. Direct counts can be undertaken in sample estuaries or other wetland habitats. plots, which will give a mean and range for Relies on skilled knowledge for reliable fieldwork and interpretation Highly skilled and time-consuming Relies on skilled knowledge for reliable fieldwork and interpretation May require a large amount of fieldwork and planning for large sites or colonies Time-consuming at fieldwork and analytical stages; wasteful if only an index required Versatile and efficient Best method of assessing mortality, productivity, etc. Versatile and efficient Simple methodology Enables interpretation of breeding distribution with habitat call identification Bird ringing licence call identification tion of species species, song and breeding behaviour Expertise required Advantages Disadvantages Potentially low Visual, song and Dependent on attribute measured Potentially low Visual, song and Underestimate Visual identifica- Underestimate Identification of Bias Poor: improved by using distance bands purposes Poor: improved by using distance bands Dependent on species involved Reasonable for its purposes Reasonable for its good for surveying dense habitats Low Good for recommended species group Low if surveying small area Highly costly per unit area compared with transects More efficient than registration mapping Not particularly good in open habitats Detectability Generally Detectability Reasonable Age structure Sex ratio Breeding success Productivity Flock or colony sizes Behaviour Territory size Density Sex ratio Density Sex ratio Other attributes Efficiency Precision Presence Index Estimate Index Estimate Index Presence Index Estimate Presence Index Estimate (for appropriate species) Population size data Most species, especially widespread or common species in open habitats All species Presence All species Presence Conspicuous, colonial or flocking species All distinctly territorial species Recommen- ded species group Methods for surveying and monitoring birds Line transects Point counts Trapping and ringing Total counts Territory mapping Table 24.1 24.2 General methods 415

population size. With appropriate sampling, this participation by BTO members), the labour-intensive can then be extrapolated to the whole area or to analytical methods it requires (registration maps the area of habitat preferred by the species. The are analysed by BTO staff) and its inability to sampling of species populations is best carried out provide measures of statistical confidence asso- by using a standardised, quantitative method – terri- ciated with each estimate. In 2001 the CBC scheme tory mapping, line transects or point counts – as was replaced as the UK’s principal bird monitoring described later. scheme by the Breeding Bird Survey (BBS), begun in For the commonest species, long-term popula- 1994. This utilises line transect methods, described tion trends can be derived from direct counts by below. simply comparing the total population counted For most EIA studies, which require a site to be each year. It should be remembered, however, that surveyed and assessed for its ornithological signifi- unless counts are known to be comprehensive and cance in respect of bird populations, the normal accurate, or effort has been carefully standardised, approach is to undertake a territory, or essentially, apparent short-term changes may prove to be arte- a registration mapping exercise. Most development facts. More often, the degree of inaccuracy inherent related sites are reasonably small (<50ha) and so in direct count data is unknown. Regression analysis coverage in one day, repeated on five occasions and log-linear models are among the tools used to during the breeding period, should be sufficient establish whether there are long-term trends in to provide reasonable data on (a) distribution, (b) counts. relative abundance and (c) records of rarer species of most conservation interest. 24.2.2 Territory mapping However, some EIA studies require data to be collected on all manner of groups from farmland Principles birds, estuary waders and wildfowl, overwintering Territory mapping is used to estimate abundance ducks on large waterbodies, seaducks at sea, sea- and to examine the distribution of birds in relation bird colonies, geese flighting between roosts and to habitat or other environmental variables. The feeding grounds, EU Annex I species on specially method relies on the fact that many bird species protected sites, etc. Specialist methods are avail- show conspicuous territorial behaviour when able for surveying and monitoring these species breeding. A series of mapped registrations for a or groups. This Handbook gives broad guidance for particular species, gathered over several visits, some of these, with more specific treatment of will usually show signs of clustering, indicating the a number of high-profile species of conserva- locations of territories. The number and distribution importance. The reader is referred to Bibby tion of territories can then be assessed across the et al. (2000) for further details. whole site. The method works best for species that are extremely vocal, such as Wrens Troglodytes tro- Field methods glodytes and other songbirds, but does not work Between five and ten field visits are usually made, well for species that show little territorial behav- during which the observer aims to cover the whole iour or move long distances from their breeding site evenly, to within 50 m of every point. Birds are sites, e.g. Grey Heron, Woodpigeon Columba palum- usually recorded up to 50 m outside the boundary bus and most corvids. of the survey site in an attempt to ensure that One form of territory mapping, the Common territories that overlap with the boundary are Bird Census (CBC), has been used for many years included. by the BTO as the principal method for monitoring Between 50 and 100 ha can be covered in a 3–4 farmland and woodland bird populations in the UK hour visit, the timing of which should coincide (Marchant et al., 1990). The CBC was phased out with the main singing period of the target species. as the main bird monitoring scheme, however, All birds and their activities are recorded on a separ- largely because of its complexity (which limits ate map (at least 1 : 2500 scale) for each visit, taking 416 24 BIRDS

care to differentiate between individuals of the surveyed by transects (and point counts; see same species. Section 24.2.4). Line transect methods are efficient One of the most important points is to record as they enable the observer to cover large areas in instances in which two individuals are seen or a relatively short time on foot, or in a vehicle such heard singing simultaneously; this helps with as a boat or aeroplane. If exact distances to bird the interpretation of clusters of records and hence contacts are measured, results can be adjusted assists in the definition of territory boundaries. to take account of declines in detectability with For further information and detailed field distance from the observer (Section 10.6). Line instructions see Marchant (1983). Appendix 6 out- transects can also be used to count indirect mea- lines the equipment required for surveying birds sures of bird populations or activity such as by territory mapping. droppings.

Data analysis and interpretation Field methods The method should exclude (where possible) The method for collecting data will vary according counts of juveniles, plus unusually high counts to the aims of the survey and the species involved resulting from the movement of non-breeding (see Section 10.6 for general principles). The obser- birds into the area. Data from field maps are trans- ver may decide to record the age or sex of bird posed on to one map for each species, and clusters contacts, to record only one species, or to record of registrations that indicate territories are identi- many species. Birds in flight are usually recorded fied. The minimum requirement for confirming a separately from those that are perched or swim- territory is that no more than one pair of birds is ming. This poses some problems for recording recorded at a certain location on at least two visits, numbers of Swallows Hirundo rustica, Martins, 10 days apart. Counts of territories from different Swifts Apus apus, Kestrels Falco tinnunculus and sing- years can be analysed statistically by using standing Skylarks Alaunda arvensis. A general rule may be ard tests (Part I, Section 2.6.4). Territory maps from to record some species when they are first observed different years can be compared to assess range ‘using’ the habitat on a transect. For example, a contractions or expansions. Kestrel may be recorded as a fly-over until it hovers in search of prey, when its location is marked and 24.2.3 Line transects its distance from the line recorded. Similarly, Swallows may be recorded if they are noticed Principles hawking over a piece of grassland near the trans- Line transects are carried out by a surveyor, who ect. In all these cases, it is vitally important to walks along a line and either records the perpendi- ensure that birds are not double-counted as they cular distance from detected birds to the line (see move around the observer. The equipment recom- Box 10.1) or places each individual within two or mended for surveying birds by line transects is more distance bands (Section 10.6). These data can listed in Appendix 6. then be used to calculate densities. The method is generally used to estimate the populations of spec- Data analysis and interpretation ies that are either too common or too widespread The level of data analysis will depend on the aim of to estimate by using direct counts, or too elusive for the survey and monitoring programme and the the whole population at any site to be reliably amount of information collected. detected. If the aim is to survey bird numbers, changes Line transects are best suited to open habitats, in the number of raw encounters can indicate e.g. farmland and moorland, rather than enclosed change in abundance, so long as the method is habitats, such as woodland and scrub, especially fully standardised from year to year. However, where the habitat structure in the latter is fine- thisassumesthataspeciesdoesnotbecomeprop- grained. Large conifer blocks, however, may be ortionally more detectable as population density 24.2 General methods 417 increases, or as a result of a change in its habitat Data analysis and interpretation preference (or a change in the habitat itself) over The area sampled around each survey point is nor- time. Differences between surveyors are also com- mally a circle, so methods used for analysing point mon causes of change in detection rates between count and transect data differ slightly. At the very years. least, the method gives a good indication of species If there is any indication that detectability will presence–absence and of their association with affect the results of a study (this can be quickly habitat variables if these are recorded at each ascertained on a pilot survey, or by reference to point. Relative abundance estimates for the com- literature), then distance sampling may be more moner species (accounting for differential detect- appropriate (Section 10.6). Although standardisa- ability) can also be obtained. Point counts can be tion is still important, distance sampling has the used to estimate absolute abundance, by using the advantage that each year’s data can be corrected Distance software. Change between years where separately for incomplete detection. Analysis is car- this is required can usually be determined by ried out by using the computer program Distance using standard tests (Part I, Section 2.6.4). (Section 10.6.4) and changes in abundance can For a fuller description of point transect usually be determined by using standard tests methods, the various levels of interpretation and (Part I, Section 2.6.4). using the Distance program, see Section 10.6. For a fuller description of line transect methods and the use of the Distance computer program see Section 10.4. 24.2.5 Constant effort trapping and ringing 24.2.4 Point counts Principles Principles There are numerous methods used for catching and marking birds. The simplest of these is mist Point counts are similar in many respects to line netting, although this is only really suitable for transects: they are essentially a transect of zero monitoring passerines. The BTO Constant Effort length. They are, however, better suited to fine- Site (CES) scheme began in 1983 and standardises grained or dense habitats, such as woodland and mist netting at sites with an aim of assessing popula- scrub, and are safer to use in steep or difficult tion trends, survival rates and the productivity of terrain. They are also preferred if birds are likely common passerines (Peach et al., 1998). Trapping to flee from the observer before they are detected. and ringing birds is a highly skilled activity and Point counts used for distance sampling require requires a licence (see Part I, Section 2.4.3). The that greater care is taken over estimating the dis- BTO administers ringing licences on behalf of tance between the bird and the observer, and are JNCC. If the surveyor can enlist the help of local less efficient than line transects in terms of the ringing group members, who are prepared to carry amount of data collected per unit time. Habitat out regular mist netting, CES methods may prove and other environmental information, however, useful for site monitoring where data on producti- can be accurately applied to each point, so it can vity and survival are required. be a cost-effective method for collecting sample information from more structurally complex habitats. An example of a study that has used this Field methods approach is that of Hill et al. (1990). CES requires ringers to conduct mist netting at least once in each of 12 periods of 10–11 days Field methods from May to August. Visits should be conducted at General field methods and equipment are the same least 3 days apart to minimise the problem of birds as for the line transect method (Section 24.2.3). learning to avoid nets placed in standard locations. Point counts are also described in Section 10.8. As well as net position, net length and timing is 418 24 BIRDS

also kept constant at each site. Mist netting usually levels of bird mortality associated with various takes place between dawn and a fixed time in late structures such as wind turbines and communica- morning. Each capture is identified, aged and sexed tions towers. When conducting such surveys a vari- where possible, and fitted with a uniquely num- ety of factors must be considered to ensure the bered aluminium ring. accuracy of the data collected. For instance, the frequency and timing (both day and seasonal) of surveys, search efficiency and scavenger activity Data analysis and interpretation can have a significant influence on the survey Assuming there is no difference in the probability results, if not taken into account. It is important of capturing juveniles and adults, the ratio of juven- to include control sites (some distance from the ile to adult captures gives an estimate of productiv- study site) to establish a baseline of mortality and ity. However, birds may leave the trapping area or controlled carcass drops on the study site to assess disperse into it from other sites. Individual marking search efficiency and levels of scavenger activity. allows the researcher to assess the significance of The data collected during collision mortality immigration and emigration as the change in the monitoring surveys should include the location of proportion of recaptured birds over time. carcasses, the number of birds and species Survival rates can be assessed by using mark involved, and the weather conditions preceding and recapture of individually marked birds. CES- the search. type data may also be used to identify the number of adults and juveniles recaptured in successive years as an estimate of survival rates. This 24.3.2 Flightline surveys requires that the probability of recapture remains constant across years and that any correlation Flightline surveys are an adaptation of the point between age and survival is accounted for. One count method described earlier. These surveys are method of assessing survival rates is by using mod- used to assess the potential impacts of develop- elling software such as SURGE (Clobert et al., 1987; ments such as airports and windfarms on bird Pradel et al., 1990). Population change or the num- behaviour, migration and local movements ber of breeding pairs can also be estimated from through the study area. The objective of such sur- recaptures of adult birds (e.g. individuals captured veys is to identify important avian flight paths to on two visits, at least 7 days apart) or females with and from sites used by birds for various activities brood patches. This has been shown to correlate (e.g. feeding, roosting). When conducting such sur- well with data collected on the number of breeding veys a number of factors should be considered. For territories by using territory mapping methods instance, the frequency and timing (both day and (Boddy, 1993). seasonal) of surveys need to coincide with the avian activity being assessed. In addition, when selecting the survey viewpoint, it is important that the wider 24.3 SOME SPECIFIC METHODS USED IN area being studied is clearly visible, while ensuring SPECIALIST EIA STUDIES the surveyor(s) does not influence the birds’ flight patterns and behaviour. The data collected in such The following methods are currently employed in a surveys should include the altitude, direction, number of major EIA studies. number of birds and species involved, and weather conditions during the survey. The length of survey 24.3.1 Collision mortality monitoring period will be determined by the length of activity period of the birds. A series of scoping visits to Collision mortality surveys are adaptations of record time of day of activity, spread of activity the line transect method described previously. and approximate numbers of birds involved will The objective of such surveys is to identify the enable the full survey to be fine-tuned. 24.3 Specific methods for EIA studies 419

stellatus). Data obtained by satellite tracking can be 24.3.3 Seabird surveys at sea downloaded remotely on a regular (e.g. daily) basis Surveys of seabirds at sea are primarily a variation to a computer, making the actual data capture on line transect methods. The objective of such extremely cost-efficient. surveys is to identify the potential impacts on resident and migratory marine birds of the construction of structures such as wind turbines in shallow 24.3.5 Nocturnal surveys productive waters during different periods of the All recognised standard generic bird surveys, birds’ annual cycle. A recognised industry standard i.e. breeding (BBS, registration mapping) and win- method for this type of survey has been developed tering (WeBs) bird surveys, and most species- by COWRIE (Collaborative Offshore Wind Research specific surveys, are carried out during daylight into the Environment). In summary, this involves hours. The nocturnal behaviour of birds is becom- trained, skilled offshore ornithologists, using a suit- ing increasingly important in assessing the impact ably specified vessel to steer a course at a specific of development proposals. For example, many speed (10 knots) along a series of transect lines large water bodies hold large populations of migra- (max. 300 m apart) in the study area. A number of tory waterfowl, yet it is apparent that their use may surveyors record their observations (species, num- often be restricted to providing refuges rather than ber, activity, direction of flight) of seabirds in dis- feeding habitat, with birds flighting out to sur- tance bands (0–50 m, 50–100 m, 100–200 m, rounding land to feed under the cover of darkness. 200–300 m, 300+ m) from either side of the vessel. An understanding of this process is extremely The survey is repeated a number of times to pro- important where site designations are concerned; vide a statistically representative baseline evalua- protection afforded to refuge habitat may not safe- tion of the avian presence in the study area. The guard the species if it needs feeding habitat in the start and end times and locations should be chan- vicinity which remains unprotected. Statutory ged to ensure the time of day at which a particular bodies and NGOs are increasingly looking for stud- area is surveyed is varied evenly across the survey ies to provide information on the impact of devel- area. This is to take account of seasonal, diurnal opments on nocturnal avian behaviour through and tidal rhythms in the area. GPS can be used to the identification of important nocturnal habitats, fix locational information such as start and end e.g. Golden Plover Pluvialis apricaria feeding adja- points. cent to roads; migratory birds’ nocturnal flight paths near communications towers; and waterfowl 24.3.4 Radio tracking feeding and roosting habitat around reservoirs. Existing techniques involve surveyors equipped Radio or satellite tracking is a technique involving with night-sights observing and recording data by the fitting of small lightweight transmitters to using standard line transect or point count birds. Radio receivers or satellites can then track methods. However, with increased image quality, the birds’ movements, which are then plotted on infra-red (IR) cameras allow the development of maps. These data provide additional detailed infor- cost effective techniques that avoid the need for mation, especially when used in conjunction with surveyors to carry out night-time observations field observations. The data obtained from these and hence reduce the potential reduction in data studies provide greater understanding of foraging quality issues associated with survey or fatigue, etc. ranges, distribution, species interaction, habitats The IR techniques involve the setting up and appro- used and interactions with natural and man-made priate siting of IR cameras, which then record the landscape features. It is particularly useful for spe- avian activity (e.g. flight path, feeding areas) to cies with large territories or ranges (e.g. large rap- appropriate data storage media (videotape, CD). tors) or secretive species (e.g. Bittern Botaurus The images are then reviewed by using an 420 24 BIRDS

appropriate interface. This technique is still in its infancy but has the potential to enhance the iden- Box 24.2 Attributes of Nightjar tification of important habitats that are used by birds at night, allow a better understanding of ATTRIBUTES INDICATING THE SPECIES’ their nocturnal behaviour, and hence provide evi- STATUS DURING THE BREEDING SEASON dence as to how this behaviour may be affected by the developments being proposed. * Number of individual churring birds; * Number of territories

24.4 SOME KEY SPECIES REGULARLY CONSIDERED IN EIA STUDIES INTERPRETATION Number of individual churring birds = number Barn Owl Tyto alba of territories = number of breeding pairs. Surveying for Barn Owls requires a Schedule 1 licence. A brief summary of the methods follows. For a detailed methodology, refer to Gilbert et al. sites identified during the winter survey to look (1998). The attributes indicating the status of this for signs of nesting activity; then to record the species and their interpretation are detailed in presence–absence of birds, their activity, sex, age, Box 24.1. A national monitoring programme for and map the location of nests. the Barn Owl is organised annually by the British Trust for Ornithology. Nightjar Caprimulgus europaeus Population survey: breeding season A brief summary of the methods follows. For A minimum of two visits should be made, one a detailed methodology, refer to Gilbert et al. between November and January and the second (1998). The attributes indicating the status of this between the beginning of June and the middle of species and their interpretation are detailed in July. The winter visits may be carried out at any Box 24.2. time of day; the summer visit should be carried out in late afternoon. The aim of the winter survey is to Population survey: breeding season search all potential nest sites and to record signs A minimum of two visits should be made between (e.g. pellets, feathers, droppings) of Barn Owl pre- the beginning of June and the middle of July, either sence. These signs are recorded on a map. The at dusk or an hour before dawn. Surveys must not summer visit aims to revisit all the potential nest be undertaken during windy and wet conditions. Two surveyors work together to locate the position of churring birds, which can be difficult to pinpoint from one location. This may be achieved by posi- Box 24.1 Attributes of Barn Owl tioning the surveyors 50–100 m apart and triangu- lating the direction of the churring bird and hence ATTRIBUTES INDICATING THE SPECIES’ its location. As with territory mapping techniques, STATUS DURING THE BREEDING SEASON the location of churring birds is plotted on a map. At the end of the study all locations of churring * Number of active nest sites birds are transferred to a single master map; those records believed to be from the same bird are INTERPRETATION enclosed in a territory boundary. The total number Number of occupied Barn Owl nest sites of separate churring males can be used to deter- found = Number of breeding pairs of Barn Owl. mine the number of territories and hence the number of breeding pairs. 24.4 Key species for EIA studies 421

Woodlark Lullula arborea Woodlarks start to show signs of territoriality early in the year the first visit is carried out between 15 A brief summary of the methods follows. For February and 21 March, second between 22 March a detailed methodology, refer to Gilbert et al. (1998). and 25 April, and the final visit between 26 The attributes indicating the status of this species April and 1 June. Visits should be made before mid- and their interpretation are detailed in Box 24.3. day. All observations of birds and their behaviour are plotted on a visit map by using standard Population survey: breeding season BTO codes. After the final visit all records are trans- Breeding population surveys require that three ferred to a single master map; those records separate visits be made to the survey area. As believed to be from the same pair are enclosed in a territorial boundary. Most territories will be deter- Box 24.3 Attributes of Woodlark mined through the presence of separate singing males. Simultaneous singing males, foraging pairs ATTRIBUTES INDICATING THE SPECIES’ and flight directions help to identify territory STATUS DURING THE BREEDING SEASON boundaries, which establish the number of breeding pairs. * Number of separate singing males * Number of territories Black Redstart Phoenicurus phoenicurus

INTERPRETATION A brief summary of the methods follows. For a Number of separate singing males = number of detailed methodology, refer to Gilbert et al. (1998). territories = number of breeding pairs. The attributes indicating the status of this species and their interpretation are detailed in Box 24.4.

Box 24.4 Attributes of Black Redstart the number of males heard singing at the same place on two or more occasions, or ATTRIBUTES INDICATING THE SPECIES’ STATUS the number of episodes of courtship or display beha- DURING THE BREEDING SEASON viour observed, or the number of sites where birds are seen visiting a possible nest site, or * Number of confirmed breeding pairs the number of sites where adults show agitated beha- * Number of probable breeding pairs viour (e.g. anxiety calls), or * Number of possible breeding pairs the number of nests observed being built * Minimum number of breeding pairs = the number of probable breeding pairs. The number of sites where a Black Redstart is seen in INTERPRETATION non-ideal nesting habitat during the breeding season, or The number of nests containing eggs or young, or the number of singing males heard once during the the number of recently used nests, or breeding season, or the number of sites where adults are seen carrying food the number of birds seen in possible nesting habitat for young, or during the breeding season the number of sites where recently fledged young are = the number of possible breeding pairs. seen The number of confirmed pairs ¼ the minimum num- ¼ the number of confirmed breeding pairs. ber of breeding pairs. the number of pairs of Black Redstart seen in ideal The number of confirmed þ probable þ possible bre- breeding habitat in the breeding season, or eding pairs ¼ the maximum number of breeding pairs. 422 24 BIRDS

Population survey: breeding season Mapping of simultaneous registrations (eg. singing At least five visits should be made between mid April birds) is particularly important in analysis of maps and the end of June. These should occur either in the to determine numbers. A territory is likely to be early morning (within an hour of sunrise) or in the occupied if a singing male, territorial dispute or evening leading up to sunset. Surveying in cold, wet breeding activity is observed. and windy conditions may yield poor results and is not recommended. A survey route should be marked on a map and followed each visit. Singing birds are 24.5 BIRD CONSERVATION EVALUATION listened for and each visual or audible encounter CRITERIA recorded. The location and behaviour of the record is plotted on a visit map with standard BTO codes. Key evaluation considerations After the final visit, transfer all records to a single Bird populations, particularly in the UK, are gen- master map. The data are used to assess the number erally more regularly and thoroughly surveyed of breeding Black Redstart present by using the inter- and monitored than is any other group of taxa. pretation criteria described in Box 24.4. This has led to a long history of bird monitoring in the UK, with an effective network of many Dartford Warbler Sylvia undata highly skilled amateur and professional ornithologists involved in collecting data. Many of the A brief summary of the methods follows. For a long-term national monitoring schemes are run detailed methodology, refer to Gilbert et al. (1998). by partnerships between non-government conser- The attributes indicating the status of this species vation organisations (e.g. the British Trust for and their interpretation are detailed in Box 24.5. Ornithology, the RSPB and the Wildfowl & Wetlands Trust) and the UK statutory conserva- Population survey: breeding season tion agencies. Three visits should be made, the first between April As a result the population sizes, range distribu- and mid-May, one between mid- and late May and tions, population and range trends, migratory the last one in June. Surveys can be carried out movements and many key aspects of breeding suc- from an hour after dawn onwards through the cess and survival are relatively reliably known and day. Dry, calm conditions are most favourable for documented for many bird species. Outside the UK Dartford Warbler surveys. On a visit map record all it has also been possible to define and quantify Dartford Warbler encounters. After the final visit flyway populations, identify key migratory staging transfer all records to a single master map; circle posts and assess the conservation status of birds at those records believed to be from the same pair. a European level.

Box 24.5 Attributes of Dartford Warbler INTERPRETATION

* Number of occupied territories = number of sepa- ATTRIBUTES INDICATING THE SPECIES’ STATUS rate singing Dartford Warbler + number of separate DURING THE BREEDING SEASON territorial disputes + number of observed episodes * Number of separate singing males of breeding activity. * Number of separate territorial disputes N.B. When reporting total number of occupied * Number of observed episodes of breeding activity territories, include a separate note of the number of singing males only. 24.5 Bird conservation evaluation criteria 423

This has allowed the development of relatively estuaries for birds displaced from eastern Britain sophisticated and largely quantitative criteria for and continental Europe (Ridgill & Fox, 1990). the assessment of species and their conservation Without the protection of such sites, whole popu- priorities. Most site evaluations for birds may be lations of birds may be put at risk during severe carried out by reference to quantitative assessment weather events. Site selection and evaluation criteria provided that reasonable quantitative data assessments therefore need to take into account are available for the site in question. There are such possible occasional but critical uses. SPA and various sources of reliable information relating to SSSI selection criteria therefore include the capa- species distribution and abundance in the UK. city to select sites that are only used under infre- These include Gibbons et al. (1993), Lack (1986), quent conditions. Lloyd et al.(1991), Stone et al.(1997), WeBS data In the evaluation of the avian conservation (see www.bto.org) and annual summaries of the value of a study area that has been surveyed or BBS (e.g. Raven et al., 2003). A site’s existing designa- is being monitored the criteria that need to be tion status and details can be obtained online from considered include international, national, regi- English Nature or the Joint Nature Conservation onal, county and local levels of conservation Committee (see www.english-nature.org.uk or www. importance. jncc.gov.uk) for protected sites. Where a site is potentially of international There are some significant complications with importance, reference should be made to the cri- assessing the value of sites for migratory birds. The teria relating to the selection of SSSIs, SPAs, application of quantitative criteria such as the 1% Ramsar sites and IBAs summarised in Table 24.2. threshold needs to take into account the turnover A useful method for assessing the avian conser- of birds using a site rather than simply peak num- vation interest of a site at national, regional and bers present (often numbers passing through over local levels is based on bird species population size, a migratory season may be considerably greater diversity and rarity as described in Fuller (1980). than numbers seen at any one time). This is often This method is particularly useful for evaluating overlooked owing to the difficulties of measuring sites that do not have significant amounts of histor- turnover rates. ical data and are therefore reliant on data obtained Account also needs to be taken of local move- from specific avian studies. ments and the full range of requirements for a An alternative method for assessing the avian species. For instance, it is not enough to protect conservation interest of a site at national, regional the nesting habitat of a species if its only feeding and local levels is provided by the guidelines for area, which may be some distance from its breed- selection of SSSIs (NCC, 1989). These offer a scoring ing site, is destroyed. Site requirements for birds system for various habitats based on the presence therefore need to assess nesting habitats, feeding of certain key characteristic species, and give a habitats, roosting areas and possible display areas threshold value for SSSI selection. By using this (e.g. for lekking species), and to take into account system, bird community data obtained during site diurnal, nocturnal, tidal and seasonal variation in surveys can be compared both directly with other the use of these. surveyed sites and with the standard of the SSSI Another key pitfall with site evaluations for network, providing a measure of its relative import- migratory birds (including nomadic or partly ance nationally, regionally and locally. migratory birds) is that intermittently important The evaluation of a site’s historical avian conser- sites are overlooked. For example, periods of severe vation importance can also be assessed through winter weather may result in some displacement of comparison with data available from biological birds to milder regions that they would not nor- record centres, local bird recorders (for contact mally visit. Such hard-weather movements have details see www.britishbirds.co.uk), county been documented in several species of wildfowl avifaunas (e.g. James, 1996) and bird reports (see and indicate the importance of British west coast Ballance, 2004). an adequate suite of most and by concluding multilateral from Stage 1 criteria 1–3 alone. consideration, using the Stage 2 to take special account of population of a regularly occurring in Northern Ireland, the all-Ireland) species or subspecies of waterbird 2 guidelines in any season, where the (79/409/EEC) in any season. species listed in Appendix II. as defined by the Ramsar Convention) status, ecology or movement patterns selection. more birds than others and/or holding or for SPA classification. as these are adequately covered by UK and ) 2001 . 24.3 1: identification of areas likely to qualify for SPA status supporting birds at higher concentrations are favoured for application of Stage 1 guidelinessuitable 1, 2 sites or for 3 forjudgements, the a to conservation be species given does of to notmay that cases identify mean where species. that a an species’ This adequate population number allows of areas cannot be identified migratory species (other than those listed in Annex I) in any season. population of a species listed in Annex I of the Birds Directive or 20 000 seabirds in any season. Stage 2: selection of most suitable1. areas Population in size number and and density. size Areas holding or supporting requirements for birds listed under the Bern Convention Species listed on Appendices II and III. It is not normallyEuropean necessary statutory instruments. Criterion 5: supports 20 000 orCriterion more 6: waterbirds. supports 1% of the individuals in a population of one Endangered migratory species listed in Appendix I of the Convention agreements for the conservation and management of migratory 3. An area is used regularly by over 20 000 waterfowl (waterfowl 4. An area that meets the requirements of one or more of the Stage 2. An area is used regularly by 1% or more of the biogeographical 1. An area is used regularly by 1% or more of the Great Britain (or Legal context Thresholds gations on contracting parties gations on contracting parties gations on contracting parties Regional context Global None IUCN Version 3.1 criteria (IUCN, Global Legal obli- Global None See Table Summary of avian conservation evaluation criteria Table 24.2. Evaluation criteria Threatened Birds of the World Bern Convention GlobalRamsar Legal obli- Convention Bonn Convention Global Legal obli- Important Bird Areas EU Birds Directive European EU Law Stage 424 on a rapidly has declined historically but listed. moderately in recent years (by Dependent or Data Deficient. with an unfavourable conservation and determining the boundaries of are favoured for selection over those are favoured for selection. in any season, and which are vital to number of qualifying species under of occupation or use by the relevant in Europe, but which have an protected only during the breeding with internationally important Europe and which have an Unfavourable by significant proportions of the biogeo- as wide a geographic coverage across the have declined historically and not recovered. which are of global conservation concern because their status I comprise 79 rare, endangered, declining or vulnerable species. that are globally threatened, whose population or range has declined species’ range as possible. species are favoured for selection. Article 4 of the Directive are favoured for selection. SPAs for thinly dispersed and wide-ranging species. which do not. graphical population of a speciesthe in survival periods of of a severe viable weather population, are favoured for selection. 4. History of occupancy. Areas known to have a longer history 3. Breeding success. Areas of higher breeding success than others 2. Species range. Areas selected for a given species provide 5. Multi-species areas. Areas holding or supporting the larger 6. Naturalness. Areas comprising natural or semi-natural habitats 7. Severe weather refuges. Areas used at least once a decade 8. Stage 2 judgements were particularly important for selecting SPEC 2: Species whose global populationsConservation are Status concentrated in in Europe. SPEC 3: Species whose global populations are not concentrated Unfavourable Conservation Status in Europe. world-wide basis is classified as Globally Threatened, Conservation Schedule 1 Part II lists three wildfowl species that are specially season. in recent years (i.e. by more than 50%Amber in list 25 species years), or are which those whose population or range has declined more than 25% but less thanrecovered 50% recently, in rare 25 breeders years), (fewer those thanpopulations whose 300 in population the pairs), UK, those those withstatus localised in populations, Europe. and those Species that meet none of theseBirds criteria of are Conservation green-listed. Concern are those that are either Red or Amber European None SPEC 1: Species occurring in Europe National UK Law Species listed on Schedule 1 Part National None Red List species are those Species of European Conservation Concern Wildlife & Countryside Act UK Birds of Conservation Concern

425 ) 90 wintering species > 1980 seabird colonies of over 10 000 at other seasons where adequate covers mainly colonial and rare that normally contain 1% or more support an especially good range of bogs). regularly contain 1% or more of the during severe weather. breeding sites. produced as part of the UK Biodiversity 70 breeding species, are eligible for selection. In practice this > a ‘BTO Index’ given in the SSSI guidelines. quality, rarity (Fuller, ). 1998a 150 species recorded on passage in recent years. > guideline covers mainly wintering populations, but it can be applied of the total British breeding population of anyspecies. native species and total British non-breeding population of anydata are species available. Breeding aggregations and localities of very rare species. Localities breeding pairs are eligible for selection. In practice thisSmall isolated guideline colonies of seabirds andLocalities other regularly birds used and by other non-breeding birds. Localities that Localities used by birds in particularRich assemblages conditions, of e.g. breeding species. sites Localities used are eligible which High densities of waders on uplandA habitats high (including variety blanket of species and semi-natural habitats. i.e. Particularly important rare species or features. bird species characteristic of the habitat, as defined by or * * * * * * * * Action Plan programme (UKBG, A list of 26 Species of Conservation Concern (SoCC) has been Legal context Thresholds None Population size, species richness, breeding community Regional context National County, Local National UK Law Regional, ) cont. ( Table 24.2 Evaluation criteria UK BAP list of priority bird species Other SSSI selection criteria

426 24.6 Protection status in the UK and EU 427

24.6 PROTECTION STATUS IN THE UK annual cycle, including many species that are com- AND EU mon breeding or wintering wetland birds in the UK. AEWA aims to conserve migratory waterbirds, 24.6.1 BirdLife list of Threatened Birds of giving special attention to endangered species and the World those with an unfavourable conservation status. BirdLife International is the official Red Listing See the AEWA website at http://www.unep- Authority supplying information on globally threat- aewa.org for details on requirements. ened birds for IUCN Red Lists. The most recent global overview, entitled Threatened Birds of the Bern Convention Annex 1 World (BirdLife International, 2000) used the IUCN 1994 version 2.3 criteria (IUCN, 1994). Information Birds listed under Appendices II and III of the Bern from this BirdLife assessment was supplied to IUCN Convention are covered by UK and European for the 2000 IUCN Red List (Hilton-Taylor, 2000). instruments (Wildlife & Countryside Act, the In 2002, BirdLife updated this information for CROW Act and the Habitats Regulations compris- 25 species for the 2002 IUCN Red List (see ing the EU Birds and Habitat Directives). Appendix II www.redlist.org). is a long list of strictly protected fauna species Up-to-date and complete lists of globally threat- which includes a high proportion of European ened or near threatened birds can be obtained from birds. Appendix III lists other protected fauna spe- Birdlife at www.birdlife.org, together with cies, which covers almost all birds not covered in accounts for globally threatened species. Appendix II. Currently (2004), only two bird species that See http://www.nature.coe.int/english/cadres/ regularly occur in the UK are considered to bern.htm for more information on the Bern be globally threatened, both of which are Convention and lists of species on the various classed as Vulnerable: Corncrake Crex crex and Appendices. Aquatic Warbler Acrocephalus paludicola (BirdLife International, 2000). White-tailed Eagle Haliaeetus Wild Birds Directive albicilla is considered to be Near Threatened and Scottish Crossbill Loxia scotica Data Deficient (pri- The EU Birds Directive (79/409/EEC) provides for marily because its taxonomic status is unclear). the protection, management and control of naturally occurring wild birds within the European Union. Bonn Convention Annex 1 The Directive lists, under Annex I, species that The Bonn Convention aims to conserve terrestrial, are considered to be in danger of extinction, vul- marine and avian migratory species throughout nerable to specific changes in their habitat, rare, or their range by providing strict protection for the requiring particular attention for reason of the spe- endangered migratory species listed in Appendix I cific nature of their habitat. The species mentioned of the Convention and by multilateral agreements in Annex I are subject to special conservation mea- for the conservation and management of migratory sures concerning their habitat in order to ensure species listed in Appendix II. their survival and reproduction in their area of Th e o nl y bi rd sp e ci es lis te d udistribution. nd er A pp This e includesnd ix 1 the th designationat of regularly occurs within the UK is White-tailed Eagle. Special Protection Areas (SPAs) as conservation The only Bonn Agreement of direct relevance to measures for Annex I listed species, particularly birds in the UK at the moment is the African- for certain rare or vulnerable species and for regu- Eurasian Migratory Waterbird Agreement (AEWA). larly occurring migratory species of bird not listed The agreement covers 235 species of bird (listed in on Annex I, and pays particular attention to the Annex II of the agreement) that are ecologically protection of wetlands of international import- dependent on wetlands for at least part of their ance. In the UK this is implemented through the 428 24 BIRDS

Wildlife & Countryside Act 1981, where all SPAs Criterion 6 requires a definition of each species’ have first to be notified as Sites of Special and subspecies’ flyway populations and a quantita- Scientific Interest (SSSIs), apart from marine SPAs. tive estimate. These have been defined and esti- Within SPAs Member States ‘shall take appropriate mated by Wetlands International and published steps to avoid pollution or deterioration of habitats or and updated every three years. To ensure interna- any disturbances affecting the birds’. The Directive tional comparability, Criterion 6 should therefore requires the maintenance of the favourable conserva- be judged against these international popu- tion status of all wild bird species across their distribu- lation estimates and 1% thresholds (the most tional range with the encouragement of various recent being Wetlands International, 2002). activities to that end. There is also a requirement for Conventionally, assessments against the 1% thresh- the establishment of a general scheme of protection old are based on a five-year mean. for all wild birds, which is adequately addressed in the Consideration may be given when assessing bird UK by the Wildlife & Countryside Act. populations of a site to the turnover of waterbirds The Birds Directive and Annexes can be obtained at migration periods. Further information on the from the European Commission nature conserva- application of the 1% criterion can be found on the tion website at europa.eu.int/comm/environment/ Ramsar website at www.ramsar.org. nature/legis.htm. Further details of the application of the SPA criteria and the selected SPAs can be found in Species of European Conservation Concern Stroud et al.(2001) and on the JNCC website at BirdLife International contributed to establishing www.jncc.gov.uk/UKSPA/default.htm. European-wide conservation priorities by assessing the conservation status of all birds in Europe The Convention on Wetlands (Ramsar in 1994 (Tucker & Heath,1994 , BirdLife Convention) International, 200)4 and identified Species of European Conservation Concern (SPECs). Sites may be designated as Ramsar Sites (Wetlands Species are considered to be concentrated in of International Importance) under The Convention Europe if more than 50% of their global breeding or on Wetlands of International Importance especially wintering population occurs in Europe. Species are as Waterfowl Habitat, more popularly known as the considered to have an Unfavourable Conservation Ramsar Convention. Status if their European populations are small and The Ramsar Strategic Framework and Guidelines non-marginal, or are substantially declining, or are note that wetlands identified as being of interna- highly localised. tional importance under Criterion 5 should form The SPEC list has been widely used throughout an ecological unit, and may thus be made up of Europe. BirdLife has used the SPEC categories to one big area or a group of smaller wetlands. A wet- help identify priority habitat conservation mea- land is said to ‘regularly’ support a population of a sures (Tucker & Evans, 1997) and in their current given size if: criteria for Important Bird Areas in Europe (Heath * the requisite number of birds is known to have & Evans, 2000). In the UK it has been used in the occurred in two thirds of the seasons for which assessment of bird species of conservation con- adequate data are available, the total number of cern, which has been co-developed with and recog- seasons being not less than three; or nised by the UK statutory agencies. The SPEC * the mean of the maxima of those seasons in which categories and threat status assessment also pro- the site is internationally important, taken over at vide a useful means of incorporating European least five years, amounts to the required level scale conservation priorities into general site eva- (means based on three or four years may be quoted luations for management planning and EIA in provisional assessments only). purposes. 24.6 Protection status in the UK and EU 429

Important Bird Areas However, the protection afforded to individual One of BirdLife International’s main activities is the species varies depending on their listing under var- identification of Important Bird Areas (IBAs) (see ious Schedules of the Wildlife & Countryside Act (as Heath & Evans (2000) for the European set of IBAs), amended). Those on Schedule 1 receive special pro- which BirdLife recommend should receive appropri- tection and cannot be intentionally (or, in England, ate statutory protection. IBAs were initially identi- Scotland or Wales, ‘recklessly’) disturbed when fied in Europe in 1989 for congregatory and nesting. Schedule 1 Part I lists 79 rare, endangered, migratory species, globally threatened species, spe- declining or vulnerable species. Schedule 1 Part II cies and subspecies that are threatened throughout lists three wildfowl species that are specially pro- all or large parts of Europe, and species with rela- tected only during the breeding season. In tively small world ranges that have important popu- Scotland, the nests of certain bird species (in lations in Europe (Grimmett & Jones, 1989). This Schedule A1) are also protected, even when not in initiated the IBA programme, and the subsequent use, and certain species (in Schedule 1A) are pro- production of a number of national IBA inventories tected from intentional or reckless harassment. in Europe, including one for the UK (Pritchard et al., 1992). The UK inventory identified 295 IBAs. These UK list of Species of Conservation Concern sites cover more than 31 000 km2,representingover This is a joint NGO and statutory agency assess- 12% of the UK surface area. ment of the status of birds in the UK and a list of The criteria for identifying IBAs have since been Species of Conservation Concern (Gregory et al., updated and expanded globally. IBAs are now sites 2002). The following seven quantitative criteria that are important for threatened species, congrega- are used to assess each species. tory species, assemblages of restricted-range species and assemblages of biome-restricted bird species. * Global population status Sites qualify as IBAs if they meet any of the standard * Recent population decline global criteria or regionally specific criteria. Twenty * Historical decline in breeding population criteria have been developed for the selection of * European conservation status IBAs in Europe (Heath & Evans, 2000), which may * Breeding rarity categorize sites at three distinct levels, as follows. * Localised breeding and non-breeding species * International importance during the breeding or * Global (Class ‘A’ criteria) non-breeding season * European (Class ‘B’ criteria) * European Union (Class ‘C’ criteria) The criteria are then used to assess each species according to one of three categories: Red, These criteria are summarised in Table 24.3.As Amber or Green. The red list reflects only the with the Ramsar criteria, 1% thresholds for flyway extent to which a species is threatened, whereas or biogeographical populations of waterbirds should the amber list reflects both threat status and the be based on Wetlands International estimates (Rose UK’s responsibility for bird populations. Full details and Scott, 1997; Wetlands International, 2002). of the application of these criteria, the datasets Thresholds for other European populations are lar- used to test them and the list of Species of gely taken from Tucker & Heath (1994), BirdLife Conservation Concern are provided in Gregory International (2000) and BirdLife International et al.(2002). (2004).

Wildlife & Countryside Act UK BAP list In the UK all wild birds, their nests and eggs are protected under the Wildlife & Countryside Act Up-to-date lists of bird SoCCs can be obtained from 1981 (as amended), and by the Wildlife (Northern www.ukbap.org.uk/ Library together with Species Ireland) Order 1985. Action Plans for Priority Species. conservation conservation species, or other species of global 1% of the global population of a 1% of a biogeographic population population of a flyway or other distinct Area. the group of species whose approach is thought to be appropriate. population of a seabird species. at least 20 000 storks, raptors, or cranes of the restricted-range species whose or other distinct population of a which the site-protection approach is over 20 000 waterbirds or 10 000 pairs of over 3000 raptors or cranes regularly pass on Areas ’ most important in the country for a species with an unfavourable ’ most important in the country for a species with a favourable n n seabirds of one or more species. iv. The site is known orpass thought during to spring be or a autumn ‘bottleneck’ migration. site where of a congregatory waterbird species. ii. The site is known orseabird thought or to terrestrial hold, species. on aiii. regular The basis, site at is least known or thought to hold, on a regular basis, waterbird species. ii. The site is known oriii. The thought site to is hold known at or thought least to 1% hold of over 1% a of distinct a biogeographic distributions are largely or wholly confined to one biome. population of other congregatory species. iv. The site is a ‘bottleneck’spring site or where autumn over migration. 5000 storks, or The site is one of the ‘ The site regularly holds significant numbers of globally threatened The site is one of the ‘ conservation concern. status in Europe (SPEC 2 or 3) and for which the site-protection breeding distributions define an Endemic Bird Area or Secondary thought to be appropriate. status in Europe but concentrated in Europe (SPEC 4) and for Criterion i. The site is known or thought to hold at least 1% of a flyway i. The site is known or thought to hold, on a regular basis, at least The site is known or thought to hold a significant component of The site is known or thought to hold a significant component Summary of the 20 criteria used in Europe to identify Important Bird B. EUROPEAN B1. Congregations A4. Congregations B2. Species with an unfavourable conservation status in Europe Category A. GLOBAL A1. Species of global conservation concern B3. Species with a favourable conservation status in Europe A2. Restricted-range species Table 24.3. A3. Biome-restricted species

430 or of the EU population of a species SPAs. of a migratory species not considered based on ornithological criteria species, or other species of global Directive, and not listed on Annex I). on Annex I of the Birds Directive). to in Article 4.1 of the Birds Directive). waterbirds or 10 000 pairs of migratory region (NUTS region) in question for a at least 3000 raptors and/or 3000 cranes The site is known to regularly hold at least 20 000 migratory regularly pass on spring or autumn migration. The site is one of the five most important in the European seabirds of one or more species. The site is a ‘bottleneck’ where at least 5000 storks and/or species or subspecies considered threatened in the EU (i.e. listed The site is known to regularly hold at least 1% of a flyway population threatened at the EU level (as referred to in Article 4.2 of the Birds (similar to but not equal to C1–C6) in recognised use for identifying The site regularly holds significant numbersconservation of concern. globally threatened The site is known to regularlythreatened hold at at the least EU 1% level of (i.e. a listed flyway on population Annex I and referred The site has been designated as a SPA or selected as a candidate SPA ). Based on Heath & Evans (2000 C4. Congregatory: large congregations C6. Species threatened at the EU level C5. Congregatory: bottleneck sites C7. Other ornithological criteria C3. Congregations of migratory species not threatened at the EU level C2. Concentrations of a species threatened at the EU level C. EUROPEAN UNION C1. Species of global conservation concern Source: 431 432 24 BIRDS

Sites of Special Scientific Interest tion can be found in NCC (1989), but care should be taken in assessing some thresholds as many of the Details are summarised in Table 24.2. Full details of references used in the SSSI guidelines have been the SSSI ornithological criteria and their applica- superseded. 25 * Bats

Bats are nocturnal, highly mobile animals that are Because of the difficulties inherent in recording adapted to foraging for insects in a variety of habi- bats, and because surveys often produce ‘sample’ tats. Generally during the day they roost in a va- rather than absolute results, it is best to encourage riety of structures, commonly tree cavities, barns keen individuals to undertake projects in which and buildings. In winter, they hibernate in built the same methods and dates are used and the structures and underground places such as caves same search or time effort is expended, so as to and mines. reduce bias. Although unlicensed people can do Most information about bats has been obtained much good work in monitoring roosts (externally) by making emergence counts from roosts, from as well as work in the field, only trained and activity surveys with bat detectors and from moni- licensed people may disturb bats at roost, or catch toring bat boxes, with some records from a variety or handle them. of other sources. There is scope for gathering good- quality information by the use of novices with 25.1 ATTRIBUTES FOR ASSESSING minimal training, while skilled enthusiasts, especi- CONDITION ally helped by modern technology, can produce valid results from a wide spectrum of habitats. 25.1.1 Number of roosts The network of bat groups (supported by the Bat In the summer, female bats gather together in Conservation Trust in the UK) provides specialist warm sheltered locations to give birth. These training of new recruits, although expertise is maternity or nursery colonies are critical indica- patchily distributed. tors of population status and key targets for protec- Survey methods (Tables 25.1 and 25.2) include tion. Bats require warm, dry, undisturbed finding roosts by direct observation and locating locations, sheltered from predators, in which to dispersal routes and feeding habitats, often aided form maternity colonies, preferably with suitable by equipment such as bat detectors (ultrasound foraging habitat nearby. If such places are not avail- detectors), as detailed below: able, the reproductive success of the species, and * Day searches: structures (e.g. buildings, walls, consequently the population size, will decline. bridges, trees, mines and caves), finding signs The number of known roosts of a species is one and/or bats attribute that is used to define status, i.e. common, * Dusk observations: emergence counts from roosts, rare, widespread or of limited distribution. One dispersal commuting routes, flight paths from colony may roost at several separate sites during roosts, foraging habitats the breeding season and they are often faithful to * Dawn observations: aerial ‘swarming’ at roosts roost sites for many years. Therefore, it is impor- allows location of new roosts tant to monitor roosts with evidence of bats, even if

# RPS Group plc and Scottish Natural Heritage 2005. es Requires seasonal visits per year Bats use more than one roost site and some species are highly mobile, so roost counts can be unreliable Most sites are not easily searched Only produces index May disturb bats Difficult to tell how many bats actually enter the roost; further investigations required Disturbs bats Straightforward methodology assessment of cluster size Straightforward methodology May make roost and hibernation sites easier to find Allows positive identification of bat species Can reveal presence of species that may be too quiet to be Identification Direct Expertise required Advantages Disadvantag Licence required Identification of hibernating bats Identification useful, but not necessary Licence required Identification ) Myotis large colonies Favours species that hibernate in buildings, caves and mine workings species that may swarm more often or prolifically (e.g. species that use boxes less often, e.g. Horseshoes and Serotines easily searched, otherwise very poor Very high May miss its to each box Good Variable Favours Poor Good if site is Requires vis- Good Variable Little for — Other attributes Efficiency Precision Bias applicable Population size data All bats Index All bats Not All bats Index — Recomme- nded species group All bats Estimate Methods for surveying and monitoring bats Winter hibernation counts Swarming counts Bat box counts Table 25.1. Exit counts at roosts

434 Expensive equipment required High level of expertise needed Results cannot estimate population size Hibernating bats leave little or no evidence of occupation Best way of finding new roosts Reveals more information about foraging requirements heard on bat detector Simple method Fair method of establishing presence of some species in an area Identification of key foraging areas and commuting routes Can be used all year round expertise required Specific licence required signs indicating bat presence Identification of calls Knowledge of High level of bats not recorded Some species/ Variable — Poor Low Variable quality High Very high — Index of activity — — possible absence possible absence All bats Presence/ All bats Presence/ All bats — Transects Indirect assessments of presence, e.g. droppings Radiotracking

435 436 Table 25.2. Conservation status of British bats

IUCN UK conservation Estimated UK population Species des ignationa stat usb UK distrib utionc size d Barbas telle Vuln erable Rare Wi despread throughout Unknown England (although more records from the southern half of the country) and Wales

Bechstein’s Vulnerable Rare Restricted to south England May be around 1500 but very and south Wales uncertain

Lesser Horseshoe Vulnerable Endangered Mainly confined to south-west 17 000 (7000 in England and England and Wales 10 000 in Wales)

Greater Horseshoe Lower risk, near Endangered Mainly confined to south-west 4 000–6 000 threatened (close to England and south Wales qualifying for Vulnerable)

Leisler’s Lower risk, near Vulnerable Sparse records throughout 5 000–15 000 threatened (close to England, no records for Wales, qualifying for common in Northern Ireland Vulnerable)

Whiskered Lower risk, least Endangered Throughout England and 40 000 concern Wales, south Scotland and Northern Ireland

Brandt’s Lower risk, least Endangered Throughout England and 30 000 concern Wales

Nathusius’ Lower risk, least Rare Throughout the UK Unknown (only recently found Pipistrelle concern breeding in the UK)

Grey Long-eared Lower risk, least Rare South coast of England and Uncertain, may be around 1000 concern Isle of Wight

Serotine Lower risk, least Vulnerable Southern England and occa- 15 000 concern sionally in Wales. Absent from Northern Ireland Estimated 2 million Common and Estimated 2 million Common and 30 000–50 000 10 0000 90 000–160 000 Soprano Soprano 150 000–200 000 Throughout the UK Throughout the UK Throughout the UK, apart Throughout the UK Throughout the UK Wales and south-west Scotland. Absent from Northern Ireland from northern Scotland Throughout England and Vulnerable Not Threatened Not Threatened Not Threatened Not Threatened Not Threatened ) 2001 ) 2003 concern Lower risk, least concern Lower risk, least concern concern concern Lower risk, least Lower risk, least concern ); Macdonald & Tattersall ( ); Altringham ( 2003 2000 ) 2003 Altringham ( IUCN ( Bat Conservation Trust website: www.bct.org.uk Richardson ( Noctule a b c d Natterer’s Brown Long-eared Daubenton’s Common Pipistrelle Lower risk, least Soprano Pipistrelle Lower risk, least

437 438 25 BATS

no bats are present at the time of discovery, as they protected and monitored. The number of bats may become occupied at a later date. counted at the same time each year in a hibernation site can be used as an index, allowing changes 25.1.2 Roost size to be detected over a number of years.

The sizes of roosts may be used to indicate the 25.2 GENERAL METHODS status of the species in the area. However, roost size as an indicator of species condition should be Table 25.1 outlines the general methods available interpreted with caution, and is best used on a for surveying and monitoring bats. small scale to monitor the condition of a particular site for bats, rather than for assessing the popula- 25.2.1 Exit counts at roost sites tion of bats in the wider area. Bats found in a roost can be a small part of a Principles larger colony, or they may constitute the entire Direct counts of bats emerging from roosts can be colony. A study in Switzerland showed that during used to obtain comparable, quantitative results in one summer a group of Daubenton’s bats Myotis spring, summer and autumn when bats are active. daubentoni used over 100 trees in an area of wood- In summer, female bats aggregate in clusters to land less than one hectare in size (P. Richardson, give birth and nurture their young. They may, how- pers. comm.). Each visit to the roost only provides a ever, alternate between roost sites, and may also ‘snapshot’ of the colony at that time; in most cases, split into smaller groups depending on the it will not be possible to locate all the roost sites weather, food availability and colony size. used by the colony. A number of national bat monitoring schemes Regular (perhaps once per month during the are already in place involving roost counts, such as summer, and over at least five years) monitoring the ongoing annual National Bat Colony Survey of roost sizes within a site could provide a useful (since 1978) for all species and the National Bat indication of the status of the species within that Monitoring Programme (established in 1996) for particular site. Roost monitoring surveys will be eight species. Details of these schemes in the UK most informative when combined with investiga- can be obtained from the Bat Conservation Trust tive surveys to look for new roosts on the site, as (BCT) (15 Cloisters House, 8 Battersea Park Road, reduced colony sizes could mean fewer bats on the London SW8 4BG, tel. 0207 627 2629). site but could also mean that the bats have found somewhere else on site to roost. Field methods The Joint Nature Conservation Committee have Counting techniques produced a formula for assessing population The simplest method of counting bats is to wait changes in a roost monitored annually over a num- outside the roost site and count the bats as they ber of years (JNCC Common Standards Monitoring leave. Observers must not approach too closely, as Guidance for Mammals website): this would cause disturbance to the bats, or [(Population mean for reporting period – popula- obstruct their flight path as they emerge. tion estimate at designation) Â 100]/Population Thetimeofemergencewillvarydependingon mean for reporting period. weather and recent foraging success, but surveyors The population estimate at designation is the first should be in place outside the roost or potential roost count made at the site (the ‘baseline’ population). at least 15 min before sunset (Walsh et al., 2001). It is recommended that surveyors have a bat 25.1.3 Hibernacula detector with them, as this may allow identification of the species emerging. More than one species All bats hibernate in winter, with most hiding in may occupy a roost and a bat detector should unknown locations. Known sites should be enable counts of each species. If it is not known 25.2 General methods 439

which species are present inside the roost, it is distinguish between bats entering and leaving the recommended that the detector is set at 30 kHz, roost sites, enabling more accurate counts. Bats as this frequency should pick up the echolocation returning to roosts cannot be reliably counted but calls of all species resident in Britain, except for the automation allows counts to be recorded continu- Horseshoe bat species (see Section 25.2.5 for more ously through the night. It may be possible to com- details on the use of bat detectors). However, it is pare entry and exit counts to establish whether important to note that bats may not echolocate as bats are moving between roosts. A large volume they emerge, or they may do so more quietly than of results can be obtained throughout the year. An usual, so the surveyor should not rely on the detec- advantage of automation is that the system records tor alone to warn of emerging bats. over many nights, although check counts by people For large colonies, it is advisable to have a hand- are necessary for calibration. Spurious counts may held counter. Never shine a torch directly on the be caused by other species such as birds or moths or exit holes, as this may deter the bats from leaving even by raindrops. These systems can be expensive the roost. Observers should keep as quiet as possi- to construct and maintain (thousands of pounds) ble. If there is only one exit, this can be covered by if produced by a commercial company, and great one observer. If the bats emerge from more than care must be taken when installing them. If the exit one exit, there should be an observer stationed at is disturbed too much, the bats may vacate the each one. Bats may fly in and out of the roost dur- roost. ing the count period, so it is possible to overesti- Emergent bats may be recorded on video, from mate numbers if bats are counted more than once. which accurate counts can be made. Suitable Count both out and in and subtract the ‘ins’. cameras can be expensive, but they have the Some judgement is required as to when to stop advantage of creating a permanent record, which the emergence counts. According to the NBMP can be analysed in detail. (2001 ) the survey should end when there is no further bat activity for 10 minutes (but the ‘10 minute’ rule should not be applied until the Survey times main departure of bats has begun). If more than To obtain a reasonably accurate estimate of the one species of bat is roosting in the structure, it is number of bats using a roost, it is necessary to important to remember that some species emerge make several counts including the birth period much earlier than others, and the decision to stop but before flight of juveniles. Juvenile bats emerge the survey should take this into account. Once it is over a 3 week period, although the precise dates completely dark, it is usually best to stop counting will vary depending upon weather conditions because it will no longer be possible to count bats and also weather patterns earlier in the year. accurately if they cannot be seen as they emerge. If A generally accepted methodology is to make the weather deteriorates, particularly if it starts to three counts, five days to a week apart, in June rain heavily, the count should be abandoned. If (e.g. National Bat Colony Survey, Countryside bats start swarming around the emergence point Council for Wales (CCW) Lesser Horseshoe Bat and it becomes too difficult to determine how Monitoring Programme). It is pointless attempting many bats are leaving and returning to the roost, counts in periods of bad weather, when bats may the count should stop. not emerge at all. Counts are best done on warm, More sophisticated methods of counting bats windless nights. can be constructed by using infrared light beams Observers should be aware of the risks of work- positioned across the exit, connected to a datalog- ing at night, especially in remote areas, and should ger, which counts the number of times the beam is preferably work in pairs and carry mobile phones broken. No off-the-shelf systems are available, but (if reception is possible) or two-way radios. many different systems have been used in the past. Appendix 6 lists the field equipment required for If two adjacent beams are used, it is possible to surveying bats by exit counts. 440 25 BATS

Data analysis and interpretation Surveying at dawn can be useful for species such Analysis of counts is straightforward. The maxi- as Natterer’s Bat, which leave the roost after dark, mum count can be used to obtain an estimate of and often quietly, meaning that it can be possible the number of bats using a roost for comparison to miss them on emergence surveys. Dawn surveys with the following year. If surveys (either manual may also be useful for detecting tree roosts, as it or automated) have been undertaken regularly, may be difficult to tell from which tree bats are numbers can be plotted against time to give an emerging as it becomes dark; swarming bats indication of changes in use by bats. Care should returning to a roost are more visible. be taken when interpreting variation of counts in one season; numbers may fluctuate on account of Field methods many factors such as weather, food, roost availabil- Walking through potentially suitable bat habitat, ity and disturbance. Therefore, if trends are to be for example along rides in woodland, one hour detected, several counts are needed per site and before dawn with a bat detector can locate bats many sites should be covered simultaneously over swarming outside a roost entrance. Swarming a wide area. This method may not be appropriate activity is thought to occur throughout the sum- for some highly mobile species (e.g. Natterer’s Bat mer, with the peak in swarming around hiberna- Myotis nattereri). tion sites occurring in September. If only one roost site is known and monitored for During the day, walk through the site and iden- a particular colony, care should be taken when identify potential roosts, by looking for trees with suit- tifying possible trends. Bats often move between able cavities and holes, or buildings with access roosts; it is feasible that not all the bats from a points. Plan a transect route that is safe to walk just colony might use a monitored roost site in one before sunrise. Start the transect one hour before year. This could be interpreted as a population sunrise and walk slowly around the transect route crash, whereas the colony might simply have with a bat detector set at 30 kHz. As with evening moved to another unknown site. In Scotland there emergence, different species return to their roosts is a tendency for nursery clusters to be more faithful at different times. Long-eared bats return earliest to one roost than is the case in lowland England. and noctules latest. If bats are found swarming, However, comparisons of roost counts are the note the location of the structure (a GPS handset only quantitative method of obtaining estimates of may be useful for recording a grid reference). population size and thus monitoring population Appendix 6 summarises the necessary field trends; as such they form a part of most bat moni- equipment. toring programmes. Data analysis and interpretation Dawn swarming surveys are useful primarily for 25.2.2 Swarming counts locating roosts and hibernacula and would be useful at the start of a monitoring programme to try to Principles maximise the number of known sites. Bats (sometimes of several species) will swarm together, often in large numbers, around the 25.2.3 Hibernation counts entrance to roosts and hibernation sites. Bats will swarm outside hibernation sites as early as August, Principles and this behaviour can be observed through to Bats require different roosts seasonally; they may November. Swarming usually starts during the hibernate in sites that are not used in summer. If hour before sunrise. Late summer to autumn is bats are to be adequately protected and monitored, the bat mating period, and it is thought that it is necessary to know the locations of hibernation swarming activity at this time of year may be sites as well as of nursery and other roosts. related to mating behaviour. However, hibernation sites are frequently difficult 25.2 General methods 441

to locate and survey adequately because of the hibernacula, as this is an important factor influenc- underground nature of many suitable sites and ing the suitability of hibernation sites. because of the preference of many bats for hiber- Survey methodology should give due regard to nating in small crevices. the size and safety of the site being monitored. Because relatively few hibernating bats are Small, safe sites can reasonably be surveyed by a found each year, hibernation counts do not gener- single worker. Potentially dangerous sites such as ally provide a reliable index of bat abundance in an large abandoned mines should be surveyed by a area, but monitoring surveys are valuable for gain- team of people experienced in underground work ing or retaining the protection of sites and for and with appropriate safety equipment (see British research into the winter requirements of bats. Caving Council guidelines). Long-term monitoring may be useful as a general Bats may move between hibernation sites indicator of how local populations of bats are far- depending principally on temperature. Counts per ing, but is more reliably used for checking that a site should be on the same date and involve the site remains suitable for the bats that do use it. same method and search effort each winter for The exception to this is the Horseshoe bats: monitoring purposes. One person should be the more hibernation sites for these two species leader for individual sites. The field equipment (Rhinopholus ferremequinem and R. hipposiderus) are required for surveying and monitoring bats by known, relative to the overall estimated popula- hibernation counts is listed in Appendix 6. tion size, and therefore monitoring of Horseshoe For EIA studies, a single season of fieldwork is bat hibernacula contributes greatly to information usually feasible, recording presence and distribu- about the overall status of these species. tion of species across the site. The National Bat Monitoring Programme produces standard survey forms for hibernation Data analysis and interpretation counts. These can be obtained from the BCT (see Caution should be made when identifying trends: Section 25.2.1 for contact details). the number of bats using a particular site will vary A licence is required to enter known bat roosts. according to seasonal temperature, type of site, etc. A low count in a mild winter does not necessarily Field methods mean a reduction in the number of bats, but may Hibernation sites should be surveyed no more than indicate that they do not use that roost when the once per month, and no more than three times per external temperature is high. winter. More frequent disturbance risks awakening In some sites without cracks where bats may bats too often, which causes excessive energy loss hide, it is possible to make accurate counts of all and reduces survival. The key months for hiberna- bats hibernating at the time of the survey. If there tion surveys are December, January and February. are cracks, the accuracy of the count will be con- Identification skills are particularly important siderably affected. As few as 3–8% of bats actually when surveying hibernacula, especially when present may be counted (Stebbings, 1992). only part of one bat is visible. Several species may For the Horseshoe bats, which hang out when be hibernating in one site. Torchlight should not be roosting and hibernating, it is easier to make more shone directly on to bats, particularly from close accurate counts of total number of species than it is range. All crevices and cracks should be examined, for those such as the Myotis bats, which often hiber- as bats will often hibernate in these. Total numbers nate tucked away in crevices. per species should be recorded, with notes on the previous month’s weather (a week or two of very 25.2.4 Counts in bat boxes cold weather results in many bats seeking caves and mines). It is generally a good idea to record Principles temperature both inside and outside the site; it Bat roost boxes are usually fixed to trees to increase can also be useful to record humidity inside the the roost resource in an area, especially in 442 25 BATS

plantation forestry. They can form part of a regular species and numbers of bats should be recorded, monitoring programme if schemes are maintained with age assessment, especially in an autumn for long periods and bats are counted at regular survey. intervals. They are seldom used in EIA studies. Bats can be taken out of boxes and placed in a This method will not yield quantitative evidence cloth bag to calm the bat while the surveyor climbs on species abundance in an area, but will provide a down off the ladder. The lid should be replaced qualitative index of abundance per species per site. and, after identification, active bats must be They can be very useful for revealing the released to fly off. If the animals are torpid, they presence of ‘quiet’ species not usually heard on should be placed carefully at the entrance slit and the bat detector, particularly Bechstein’s Bat Myotis allowed to crawl up into the box. This prevents the bechsteinii, and also species that are under-recorded possibility of legs or wings becoming trapped, because they may be confused with other species, which may cause the accidental death of some such as Barbastelles Barbastella barbastellus. bats. The field equipment required for surveying If there are no bat boxes in situ, they can be and monitoring bats in bat boxes is summarised in installed as part of a long-term monitoring pro- Appendix 6. gramme. See Stebbings & Walsh (1991) for details of construction and siting of bat boxes. Data analysis and interpretation Bat boxes need regular maintenance. If mean- The number of bats in bat boxes may vary consid- ingful results are to be gathered, monitoring of erably from day to day. When bats are mating (late bat boxes must be a long-term undertaking (at August–October), male bats often hold territories least 15–20 years). In order to ensure that results related to specific boxes. At other seasons, num- are not biased, boxes should be maintained or bers will fluctuate depending on temperature and replaced in a staggered rotation, rather than replac- foraging needs. Bat box schemes can not only ing all boxes in any one year. provide results on which species are present in Because bat boxes are known roost sites, a the area, but will show changes due to season licence is needed to disturb them once occupancy and stage of forest cropping. An index of popula- has been confirmed, although the Bat tion size will be gained as well as relative change Conservation Trust recommends that for large pro- with time. jects in public places, a licence should be obtained Because colonies occupy territories measured in before inspection. many square kilometres, information from one scheme should be aggregated. Field methods Bat boxes are best visited in the day. Two visits per year are recommended: the first in May and the 25.2.5 Transects second in September. Boxes should not be dis- Principles turbed from June to late August while births and Transects can be used to obtain a qualitative indica- weaning occur. The timing of visits per site should tion of bat species living, commuting or foraging in be consistent from year to year. A ladder will be specific habitats. It is not possible to estimate abun- necessary to gain access to each box. For safety dance with any certainty because some bats may purposes, surveyors should work in pairs. be recorded several times and others not detected When inspecting boxes, they must be opened at all. cautiously because bats may be hanging on the lid Regular transect surveys with a bat detector can: or door. If practicable, check whether bats are present by using a torch to look through the entrance * provide an index of relative foraging activity; slit. In hot weather, bats may be highly active and * estimate minimum species diversity in an area; often fly out of the entrance slit unless a hand or * identify key habitats for commuting and foraging; cloth is placed over the opening. In most cases, the * indicate where roosts are located. 25.2 General methods 443

The principles of standard transect methods are are 39, 45 and 55 kHz. Natterer’s Bat may extend as considered in Sections 10.4.–10.5. Transects for bat high as 105 kHz, although the peak frequency is surveys will not necessarily conform to the ideal around 50 kHz. Tuning the detector through differ- theoretical transect: considerations of safety and ent frequencies until the call is at its loudest is the ease of access to sites when working after dark principle behind finding the bat’s peak frequency. often have to take precedence over scientific Russ (1999) provides a useful introduction to the rigour. In any case, it is usually desirable to plan principles of echolocation and the characteristics the transect route along specific habitats in the of the calls of British bats. With some practice at survey area. This should increase the number of call recognition, bat detectors can be very useful species detected and enable identification of key tools for bat identification at night. There are sev- habitats for bats. The National Bat Monitoring eral different kinds of detector, varying greatly in Programme (co-ordinated by the BCT) has a stan- price. Heterodyne detectors are the simplest, e.g. dard survey sheet and methodology for several bat the Batbox III (Stag Electronics). Some bat detectors species designed to produce unbiased results that such as the Pettersson have, in addition to a stan- can be pooled from surveys taken throughout the dard heterodyne detector, a time-expansion func- country. These can be obtained from the BCT (see tion, which records calls and plays them back at a Section 25.2.1 for contact details) but may not be much slower speed. Most bat detectors have sock- the most preferable way of conducting a bat tran- ets for recording devices to enable calls to be sect survey for monitoring or evaluating particular recorded for later comparison with pre-recorded sites. This section aims to describe how to carry out bat calls (e.g. Bat Detective, by Briggs & King, avail- a survey designed to maximise the number of spe- able from Stag Electronics) or (if time-expanded cies detected and identify and monitor the most calls are recorded) sonograms can be produced by important habitats present. using computer software (e.g. BatSound) which enable detailed analysis of the call structure. The Field methods BCT maintain a database on bat detector A transect can be set up anywhere. It may be desir- equipment. able to set up transect lines through known bat Walking a transect with a bat detector and foraging areas. Alternatively, if the area has not recording contacts (e.g. passes or feeding buzzes) been surveyed for bats before, a walk along a will provide an index of bat commuting or foraging fixed route around the site can be used. Whatever activity. It is not possible to make accurate counts, method is used to select locations, transects should especially if several bats are flying together, be standardised between visits in the same year, because it is not possible to distinguish calls from and between years. It is generally common practice different bats of the same species. Heterodyne to use permanent transects rather than temporary detectors translate only one frequency at a time, ones; the results obtained are usually so variable so that only some bats can be detected at one time. that introducing other sources of variation would Time-expansion detectors scan on all frequencies be undesirable. For EIA studies, a series of transects at once. For general surveys, not targeted at any through a site should be established, the number particular species, the optimum frequency at being dependent on site size and habitat which to set the detector is 30 kHz, as this should composition. pick up the calls of most of the bats found in Bat detectors translate the ultrasonic echoloca- Britain. For surveys targeted at specific species, tion calls of bats into frequencies that humans can the frequency should be tuned accordingly. hear. Different species have recognisable peak fre- Prior to commencing the survey, notes should quencies at which the call is loudest. For Greater be taken about the weather. Temperature and per- Horseshoe Bats the peak is at around 82 kHz and centage cloud cover should be noted, along with for Lesser Horseshoes around 102 kHz, whereas for information about the wind speed and rain. The the three Pipistrelle species the peak frequencies phase of the moon is also useful to record. 444 25 BATS

Surveys should commence at sunset. The route correlated to environmental variables such as tem- should be walked at a slow walking pace, kept as perature or insect abundance in different habitats constant throughout the survey as possible. throughout the season. When a bat is heard, the following information High bat activity in an area around sunset may should be recorded. suggest that roost sites are nearby. Observations of the direction of bats can be used to make estimates * The species of bat. regarding where they may be roosting. Using a map * If a time-expansion detector is being used, all of the wider area could pinpoint potential roost passes should be recorded, for post-survey sites, which could then be investigated further. analysis. Standing next to linear habitat features and * The location of the surveyors when the bat was counting bats can provide a very useful contri- heard. bution to building a picture of how bats are using * If the bat was observed, the direction of its flight the site. should be noted. * The time the bat was heard. * If feeding activity or social calls are heard, these 25.2.6 Torch counts should be noted. For this method, a powerful hand-held light is used * Any other relevant information, in particular to illuminate a transect line, and the number of bat whether the bat sounded distant; any information passes through the beam is recorded, usually with a about the habitat that could alter the bat’s echo- hand-held counter. The observer in this case can be location should also be recorded to inform the static, rather than actively walking along the tran- species analysis. sect line. This method works best for surveying The transect survey may be interrupted to moni- over large areas of open water. tor bat activity along potential flightlines such as Daubenton’s Bat is often surveyed by shining a mature hedgerows and watercourses. These can be torch at low level across water and recording important habitat features for bats, both as fora- passes. In this case, the mode of flight (very close ging habitat and as a sheltered commuting route. It to the water surface) should be sufficient to allow may be best to stand next to the habitat at sunset identification by experienced observers (note: sev- and count the number of bat passes along it, where eral species feed low over water on occasions). possible noting the direction of flight. Otherwise, a bat detector should be used to aid Whichever transect method is used, surveyors identification of species. should be aware of the dangers of working at night, and, preferably, should work in pairs with mobile 25.2.7 Assessing bats by field signs phones or two-way radios. The field equipment required for surveying and monitoring bats by Principles using transects is outlined in Appendix 6. Fieldcraft techniques can establish that a site is being, or has been, used by bats, even if there are Data analysis and interpretation no bats present or visible at the time of survey. Results obtained by using transects are usually too Although it is not possible to gain a precise quanti- variable to be analysed to give quantitative esti- tative estimate of abundance from these methods, mates of abundance. they are useful for identifying roosts and judging Transects enable determination of species pre- their importance. They can also be used to build up sence and can show the relative amount of bat a picture of patterns of bat distribution over an area activity for a particular transect during the course and judge their importance, and to obtain insights of one season. Plotting numbers of bats against into historic occupancy where bats are no longer date will give an indication of how foraging present. It takes experience to be able to assess patterns vary within one year, which may be accurately the use of a site by bats from field signs 25.2 General methods 445

alone. However, it is possible to recognise some and abundance can also be determined, but further signs such as bat droppings with only a brief period surveys may be required at a different time of the of training. Recognising field signs can be very year to do this properly. important when looking for bats in buildings and The exterior of the building should be examined other artificial structures, and can be carried out in first for places that would give bats access into the all seasons. Because bat roosts are protected, even roof space and also for features of the building that when bats are absent, indirect methods for deter- would provide bats with a suitable place to roost. mining whether bats are using a site can be very These should be noted on a sketch of the building. important. For further information refer to The Binoculars, torch and a ladder should be used to Batworkers’ Manual (Mitchell-Jones & McLeish, 1999). facilitate this. The interior of the building should then be searched. The extent of the search will Field methods depend on the type of building, but if there is an Droppings and remains accessible and safe roof space this should be The presence of bat droppings shows that a site has checked. The building should be searched for bats been used by bats. Large numbers of droppings are and evidence of bats (droppings and feeding a good indicator of a sizeable colony. Skilled obser- remains). Angled mirrors and/or an endoscope are vers can identify species and assess colony size. useful for searching in crevices. They are particu- Remains of dead bats allow critical identification. larly useful for surveys of timber-framed barns, Lofts should be examined, particularly beneath where the mortise joints can be difficult to look the apex, for bat droppings. If surveying caves, bats into. Pay attention to areas around the possible tend to favour domes in the cave roof; look on the access points observed from the outside. If the ground underneath these for droppings. Use a building has a chimney, search around it in the torch to examine cracks and crevices for droppings. roof space and also look on the floor below the It is always worthwhile examining cobwebs if any ridge beam for droppings. are present, since these will trap droppings, often in more easily visible locations. Data analysis and interpretation Results from surveys such as these are usually only Urine and oil stains valid for establishing presence–absence and rela- Staining from bat urine can often be seen on walls. tive colony size. Again this is an indication of presence or visits by If dead bats are found, these can be identified bats. Similarly, oils from bat fur will stain walls and and their age and condition assessed. This may rocks in places that bats have frequently roosted in enable inferences to be drawn concerning bat use or crawled over. of the site. For example, finding a dead baby bat can be taken as reasonable proof that the site was used Scratch marks as a nursery roost. In some caves where large bat populations were once Droppings can often be identified to species; present, large areas of rock have been worn away on with practice, the age of droppings can be esti- the cave roof where generations of bats have roosted. mated to give an indication of when the site was Scratchesfromtheirclawscansometimesbeseen last used, or for how long it has been used. With in other places where they have been roosting. experience it is possible to estimate the numbers of Experienced and skilled observers are necessary bats using a roost from the quantity of droppings. both to identify and to interpret the signs. Appendix 6 lists the field equipment necessary for 25.2.8 Radiotracking surveying and monitoring bats by using field signs. Buildings can be surveyed at any time of the year Principles to determine whether they are bat roosts. In most Radiotracking is one of the best ways to find new cases the status of the roost with respect to species bat roosts and learn more about foraging 446 25 BATS

requirements. Bats from a known roost can be advances in technology have meant that more tracked to determine how far they go to forage roosts are being found, and more Barbastelles are and what route they take, and this can lead to the being identified from bat detector recordings, lead- discovery of other roosts used by the tagged bat. ing researchers to believe that it is more common Foraging bats away from roosts can be caught and than previously thought. Its UK population size is tagged and followed back to their roost to discover still unknown and relatively few roosts are known. new roosting areas. However, specialist training Other species, notoriously those belonging to the and expensive equipment is required. Myotis genus, can be very difficult to distinguish from each other, with Whiskered M. mystacinus Field methods and Brandt’s Bats M. brandtii very difficult to tell Field methods for radiotracking are not discussed apart, even in the hand. in detail here because of the specialist training and In 2001, a female Greater Mouse-eared Bat Myotis licence required. Bats are caught near a known myotis was found, and in 2002 a young male Greater roost and a radio transmitter is attached to each Mouse-eared Bat was discovered in Sussex. The spe- bat. They are then tracked by a team of surveyors cies was previously thought to be extinct in the UK; and the bats’ movements are recorded on a map. further surveys are being conducted to determine whether or not there may still be a small popula- Data analysis and interpretation tion in the UK. This type of survey can produce information about Given the huge variation in our knowledge of the area of habitat that bats utilise for roosting and different species, and also the current lack of foraging. Following a bat during the course of an understanding as to how bats form colonies, how evening can reveal how the landscape influences colonies divide into different roost sites, when and (or not) their flight paths and perhaps how they why bats change roosts and where bats hibernate, respond to changes in the weather during an even- it can be very difficult to evaluate sites for their ing. When the maximum life of the radio tag is importance for bats. utilised (usually 7–10 days) it may be possible to The SSSI designation guidelines can be useful for investigate how often bats are switching roosts. assessing the national importance of the site, but Tagging female bats can be more useful as they may these relate to roosts and hibernacula, and decid- lead researchers to maternity roosts (although there ing how important a site is as foraging or commut- are serious issues with avoiding tagging bats that are ing habitat is especially difficult. A knowledge of lactating, and this is another reason why this should the status of bats in the area local to the site is only be carried out with well-trained researchers). currently one of the best ways to evaluate how important the site is on a local or regional level. Local BAPs are also worth consulting. 25.3 BAT CONSERVATION EVALUATION CRITERIA 25.3.2 Protection status in the UK and EU 25.3.1 Key evaluation considerations All British bats are included on Annex IV of the EU There are currently sixteen species of bat con- Habitats Directive, with some rarer species also firmed as resident in the UK. These exhibit a listed in Annex II. All British bats are listed on range of roosting preferences, diets and foraging Schedule 2 of the Habitats Regulations as and social behaviours. Our knowledge of the differ- European Protected Species. All British bats are also ent species varies greatly. For example, the range li sted on AppendixII of the Bern Convention, and foraging and roosting preferences of Greater except the Common Pipistrelle which is on Horseshoe Bats are relatively well understood, but Appendix III. T h e B er n C o nve n tio n ha s be en tr an s- in the case of the Barbastelle Bat, although it is lated into domestic legislation through the Wildlife & believed to be one of the UK’s rarest bats, recent Countryside Act 1981. 25.3 Bat conservation evaluation criteria 447

All British bat species are fully protected under * Common Pipistrelle (Pipistrellus pipistrellus) Schedule 5 of the Wildlife & Countryside Act 1981 * Soprano Pipistrelle (Pipistrellus pygmaeus) (as amended) and the Conservation (Natural * Greater Horseshoe (Rhinolophus ferrumequinum) Habitats & c.) Regulations 1994 (as amended). * Lesser Horseshoe (Rhinolophus hipposideros) Taken together, these make it an offence to: * Greater Mouse-eared (Myotis myotis)

* intentionally (or recklessly, in Scotland) kill, The current action plan objectives and targets for injure, take or possess these animals; Barbastelle and Bechstein’s are: * intentionally or recklessly damage, destroy, obstruct * access to any structure or place used by a scheduled Maintain the known range * animal for shelter or protection, or disturb any animal Maintain the size of the known populations * occupying such a structure or place; Increase the total population sizes of the species in the UK * sell, offer for sale, possess or transport for the purpose of sale (live or dead animal, part or derivative) The current action plan objectives and targets for or advertise for buying or selling these animals. Common Pipistrelle and Soprano Pipistrelle are:

The Wildlife & Countryside Act does not extend * Maintain the existing population size to Northern Ireland, the Channel Islands or the Isle * Maintain the existing geographical range of Man. All bat species are fully protected on * Restore population sizes to pre-1970 numbers Schedule 5 and 7 of the Wildlife (Northern Ireland) Order 1985. The current action plan objectives and targets for In addition, Greater Horseshoe, Lesser Horseshoe, Greater Horseshoes are: Barbastelle and Bechstein’s Bats are also listed on * Maintain all existing maternity roosts and asso- Annex II of the EU Habitats Directive, which effect- ciated hibernation sites ively requires that the best of these species’ known * Increase current population by 25% by 2010 roosting and foraging sites be designated as Special Areas of Conservation (SACs). The current action plan objectives and targets for From the Convention on the Conservation of Lesser Horseshoes are: Migratory Species of Wild Animals (Bonn Convention) came the Agreement on the * Maintain the current range Conservation of Bats in Europe, in 1994. The * Maintain the size of current populations Agreement recognises that endangered migratory * Expand current geographical range of the species can be properly protected only if activities population are carried out over the entire migratory range of The current action plan objectives and targets for the species. Its main provisions are to: restrict the Greater Mouse-eared Bat are: killing or capture of bats; protect key bat habitats; co-ordinate relevant research; and increase public * Maintain any extant populations discovered in awareness of bat conservation. The Eurobats secre- the UK tariat was set up to address some of these provi- * Enhance any extant populations discovered in sions and each year it produces national reports on the UK the implementation of the Agreement on the Conservation of Bats in Europe. These are down- loadable from the Eurobats website. 25.3.3 Conservation status in the UK The following species of bat are UK BAP Priority All British bats have been evaluated according to species. the IUCN Red List Categories and Criteria (IUCN, * Barbastelle (Barbastella barbastellus) 2003). The Bat Conservation Trust has produced a * Bechstein’s (Myotis bechsteinii) UK Conservation Status for all bats in Britain. These 448 25 BATS have been summarised in Table 25.2 along with County/regional evaluation current understanding of the species’ distribution It may be possible to evaluate the species diversity and estimated population size. of a site by comparing the minimum number of species recorded on the site to the total number of 25.3.4 Site designation criteria species recorded for the county. Most counties have a bat group who collate bat records for the National evaluation county. The Bat Group Contacts list is available from Selection criteria for nationally important sites for the Bat Conservation Trust (2001). bats are listed in the NCC Guidelines (1989, revised Another source of information for current 1995): knowledge regarding species distribution is the Distribution Atlas by Richardson (2000). Reference * Greater Horseshoe: all main breeding roosts and all winter roosts containing 50 or more adult bats to this document, as well as county bat group or 20% of local small ‘edge’ sub-populations. records, can inform site evaluation for bats because the presence of a species of bat previously * Lesser Horseshoe: all breeding roosts containing 100 or more adult bats and all winter roosts con- unrecorded in the county or where records are taining 50 or more bats should be considered for scarceintheareashouldincreasethevaluegiven selection. to the site. Local BAPs are also important when trying to * Barbastelle, Bechstein’s and Grey Long-eared Bats: all traditional breeding roosts should be consid- understand the importance of the site for bats. ered for selection if found. Traditional roosts are For example, the Serotine is a local BAP species in those which have been used by bats over a number Kent, because this county is thought to be a strong- of years. The precise number of years of roost hold for the species in the UK; therefore, although occupation required varies and is judged on a Serotines are not rare in Kent, their presence on a case-by-case basis. site in Kent is important. * Natterer’s, Daubenton’s, Whiskered, Brandt’s, Serotine, Noctule and Leisler’s: exceptionally large Local evaluation colonies with a long history of use at a particular When evaluating a site for its importance for bats, site may trigger the notification of a site for these consideration of specific habitats is important. species, but in most cases a roost will not result in Areas that are well-used by bats for foraging, parti- SSSI designation and protection should rely on cularly if more than two or three species are Section 9 of the Wildlife & Countryside Act, 1981. recorded, may be considered important for local * Pipistrelle and Brown Long-eared: protection populations of bats, especially if the habitat type should rely on Section 9 of the Wildlife & is scarce in the area. Countryside Act, 1981. Linear habitats used for navigation, sheltered * Mixed hibernation assemblages of all bat species: commuting and foraging that have been recorded all hibernacula containing (a) four or more species as being well-used by bats may be incorporated in and 50 or more individuals, (b) three species and some local plans as ‘wildlife corridors’. Small 100 or more individuals or (c) two species and 150 maternity roosts and hibernation sites that do or more individuals should be selected. In some not qualify for SSSI designation may be locally parts of Britain large sites are unknown, so in important. these areas one hibernaculum per Area of Search Knowledge of the status of bats in the local area containing 30 or more bats of two or more species is very important, as is experience. Factors to con- may be considered for selection. sider when evaluating a site are: Other than the SSSI designations for some species of bat, there is no standard methodology for evalu- * Number of species recorded ating areas for their importance for bats. * Levels of bat activity 25.3 Bat conservation evaluation criteria 449

* The nature of the survey records (for example: The Joint Nature Conservation Committee have roost, flightline, foraging area) and their relative produced Common Standards Monitoring availability in the surrounding area Guidance for Mammals (available online) which * The overall ‘picture’ of the site obtained from the gives guidance on assessing and monitoring the surveys; the way different bat habitats link condition of designated sites. Sites that support together across the site may influence their per- bats are well covered in this document, which ceived importance. For example, hedgerows link- describes targets for conditions of maternity roosts ing roost sites to foraging areas are a key habitat and hibernation sites and methods for how to for the bats in the roost assess the condition of the sites. 26 * Other mammals

There is a wide variety of methods for surveying Alternatively, breeding status can be evaluated and monitoring mammal species. Given that mam- by examining trapped females. In most mammals, mal species range in size from mice to whales, the from large to small, lactation is easily diagnosed techniques will vary considerably from one spec- and breeding condition can be established from ies to the next. Methods can be divided into indirect examining the vulva, or taking vaginal smears for methods (Sections 26.3.1– 26.3.5), which involve signs of oestrus. Although this technique does not counting signs of presence rather than the anim- give direct data on breeding success, it can provide als themselves, and direct methods (Sections an assessment of the health of a population. 26.4.1–26.4.4). If dead animals are available (e.g. from deer or Fox Vulpes vulpes culls), then post-mortem examination can provide sound data on reproductive con- 26.1 ATTRIBUTES FOR ASSESSING dition, including counts of corpora lutea in the CONDITION ovary, foetuses, and evidence of milk in the mam- 26.1.1 Population size mary glands. Breeding success can be established in populations that are regularly culled, if the cull Many mammal species are secretive and make is standardised between years and the majority of effective use of cover; this makes direct counts, animals are recovered. Kills can be aged to produce, even of small sample populations, impossible. over a number of years, a minimum number of However, larger mammals, such as Red Deer animals born in each year. Cervus elaphus occupying open ranges, can be effectively counted by direct counts. Estimates of population size for the majority of small and medium- 26.1.3 Survival and mortality sized mammals depend on indirect methods, such Estimates of survival and mortality can be made as indices of evidence left by mammals or trapping. from mortality data related to the age of indi- Population reconstructions can be made from viduals (see below), or by mark–recapture studies. knowledge of the age at death of animals dying The survival of individually marked animals from naturally or being culled, if a large proportion of one trapping occasion to the next can be estimated. the dead animals are available. Unless dead animals are found, it is not usually possible to distinguish between mortality and emi- 26.1.2 Breeding success and condition gration. Similarly, immigration and births can be easily confused, unless it is certain that the popula- Breeding success is particularly time-consuming to tion is isolated (i.e. ‘closed’). evaluate in mammals as it requires location of a sample of breeding sites and direct observation 26.2 GENERAL METHODS of young at these sites. Observer bias is also an important issue here as disturbance around a Table 26.1 summarises all the methods available breeding site may attract predators. for surveying and monitoring mammals.

# RPS Group plc and Scottish Natural Heritage 2005. Disadvan - tages Surveys may increase predation pressure through signs of disturbance near sites Related species may have similar or indistinguishable droppings Does not estimate numbers good for species with obvious sites method for elusive species Can identify individuals to investigate population structure through DNA analysis Simple methodology Expertise required Advantages Identification A useful Identification of signs and food species confidence limits to estimates plant damage depends on abundance of other foods Activity is related to season Low Underestimate Identification Relatively Reasonable Can attribute Low Level of food Can be time - consuming if large areas are searched to provide a reliable population estimate for some species (e.g. deer, Rabbits) aquickand easy measurement, but only gives a relative index Other attributes Efficiency Precision Bias Presence of young from food signs Distribution Can be used Distribution Can provide Popula- tion size data Presence Index Estimate Presence Index Estimate Presence Index Recom- mended species group Carnivores Rodents Lagomorphs Carnivores Ungulates Lagomorphs Rodents Carnivores, Ungulates Rodents Lagomorphs Insectivores Methods for surveying and monitoring mammals Table 26.1. Counting breeding sites or nests Faecal pellet counts Feeding signs

451 Disadvan - tages Only establishes territory boundaries or home ranges Labour - intensive Does not estimate numbers Difficult to distinguish some species Cannot be used to estimate numbers Closely related species may be difficult to distinguish High frequency of surveys is required Simple methodology Simple methodology Good for elusive species Simple methodology Less invasive than trapping Can be used to examine population structure through DNA analysis gained on health, age and physiology Identification of latrines Expertise required Advantages Identification of signs Hair analysis, identification Identification Data can be marking is dependent on season related to season leave more hair than others and are more mobile more prone to traffic accidents Reasonable Territory Low Activity is Low Some species to establish territory boundaries and home ranges a quick and easy measurement but only gives a relative index Requires low collection effort, but identification may be time - consuming Low Low Some species Other attributes Efficiency Precision Bias Distribution Can provide within a site ture Health Sex ratio Popula- tion size data Presence Index Presence Activity Presence Age struc- ) Recom- mended species group Carnivores Presence Distribution Can be used Carnivores Ungulates Rodents Lagomorphs Insectivores Carnivores Rodents Insectivores Carnivores Insectivores Rodents Lagomorphs cont. ( Bait marking Table 26.1 Tracks Hair tubes/ catchers Road kills

452 Aerial counts are often expensive; not effective in forested areas Individuals likely to be missed at high densities or in thick vegetation Counts of small areas may be unrepresentative; vegetation cover affects detectability Traps can be expensive, particularly for larger animals, and time- consuming when animals occur at low densities 2 can be carried out quickly; provides a count of all individuals, enabling coverage of a large area for surveying areas of less than 1000 km require less effort than transect counts A variety of data can be collected from captured individuals Identification Aerial counts Identification Easiest method Identification Efficient and Identification Handling Construction and errors relating to inaccurate mapping of sites estimate, may be unrepresentative of habitat declines with distance from the observer Some individuals or species are more ‘trap- happy’ than others; weather conditions also affect trappability Reasonable Underestimate Low Under- Low Detectability Good (if traps are in place long enough) Good for conspicuous species in large areas consuming Good for conspicuous species conspicuous species Labour- intensive: traps must be checked a minimum of every 4 hours for insectivores, especially shrews Information on distribution and sex and age ratio Sex ratio Can be time- Sex ratio Good for Sex ratio Population structure Age ratio Index Estimate Can provide accurate counts of ungulates over small areas Presence Index Estimate Presence Index Estimate Presence Index Estimate Ungulates Presence Ungulates Lagomorphs Sometimes rodents and carnivores Rodents Ungulates Lagomorphs Rodents Lagomorphs Insectivores Carnivores Ungulates Timed searches Transects Point counts Live trapping

453 Disadvan - tages Requires several trapping occasions Analysis can be complex Not appropr - iate if species have large home ranges or are strongly territorial Numbers vary owing to changes in land use, activity of gamekeepers and fluctuations in the population, so assumptions are often violated Provides most accurate, unbiased results Low costs; data are readily available Expertise required Advantages Identification Handling Construction Data analysis Identification Data analysis Low if correct model is applied Under- estimate, especially when dependent on natural mortality searches Good if assumptions are met and trapping effort is sufficient Variable, depending upon methods and available data be time - Requires several trapping occasions and data analysis can consuming Quality of information varies between species and sites Other attributes Efficiency Precision Bias Emigration Immigration Recruitment Population structure Sex ratio Population structure Popula- tion size data Estimate Survival Estimate Age ratio ) Recom- mended species group Rodents Lagomorphs Insectivores Carnivores Ungulates Lagomorphs Ungulates Carnivores cont. ( – (e.g. game Mark recapture Table 26.1 bag records) Mortality data methods

454 26.3 Indirect methods 455

26.3 INDIRECT METHODS A standardised search for Badger setts, such as that outlined in the national survey undertaken by 26.3.1 Counting breeding sites Cresswell et al. (1990), is the methodology most Principles commonly used for surveying Badgers and can pro- Counts of breeding sites are useful for species vide a good indication of Badger density (see also with obvious nests or burrows such as Badger Section 26.5). Meles meles, Rabbit Oryctolagus cuniculus, Fox, and Foxes are known to commonly use more than squirrels. Artificial nest boxes have also been used one den at a time, making estimates of population to survey the presence and monitor the distribu- size impossible from earth counts. tion of Red Squirrel Sciurus vulgaris and Dormouse Nests of some mammal species, such as those of Muscardinus avellanarius. Small mammal burrows squirrels and Hedgehog Erinaceus europaeus can be can be examined for activity. However, other sur- used to monitor species presence. Hedgehog nests vey methods (discussed below) are more reliable. are often difficult to find but are most easily Breeding site counts can be used to give an indi- recorded in late winter at ground level in sheltered cation of population size by calibrating against the cavities. Great care is necessary not to disturb the number of individuals present, although this insulation of hibernation sites, and it is perhaps requires the additional use of a direct monitoring safest to leave this work until the weather condi- method as outlined below. tions suggest the end of hibernation. At present, records for these two species can only provide presence–absence estimates. Field methods Nest boxes set up in sites known to hold Red An area must be searched systematically for all nest Squirrel populations or Dormice can be used sites. It is necessary to record the activity of a breeding under a standardised monitoring scheme and in site, as some may be disused. If the average number of association with a mark–recapture methodology individuals using each breeding site can be deter- to estimate population abundance. However, such mined independently then this can be converted a scheme is time-consuming and would require a into a density estimate, provided that it is possible licence, as it is an offence to disturb Red Squirrel or to estimate the total range of the population. Dormouse breeding sites under Schedule 5 of the Otherwise, counts of breeding sites can only provide 1981 Wildlife & Countryside Act and the Wildlife ameasureofpresence–absence. If counts from differ- (Northern Ireland) Order 1985 (for Red Squirrels ent sites are to be compared, survey methodology only). Alternatively, simple transect counts of must be standardised to ensure that the same area is food remains (e.g. cones and nuts) can be useful in searched at each location with the same search effort. providing indices of abundance, and at the very Trained dogs can be used to aid location of nest least can give some indication of their distribution sites for some species, such as mustelids. Care within a site, or direct counts can also be under- must be taken not to disturb individuals at a site taken (see Sections 26.3.2 and 26.4.1). The field or inadvertently increase predation levels by leav- equipment required for surveying and monitoring ing unnecessary tracks or disturbed vegetation. mammals by using counts of breeding sites is listed Outside the breeding season, burrows and nests in Appendix 6. can still be recorded for some species, although activity may be reduced, making accurate identifi- Data analysis and interpretation cation more difficult. Rabbit burrows, for instance, Breeding sites of some species can be difficult to can be counted in late winter; 1 km line transects distinguish, and inclusion of abandoned sites may are recommended (Macdonald et al., 1998). The result in an overestimate of population size. number of burrows in use is linearly related to Breeding sites may be counted to give an index of the number of Rabbits. This method can also be population size if the average number of indi- used in conjunction with faecal counts. viduals using a breeding site can be determined. 456 26 OTHER MAMMALS

Counts can then be compared annually and the Field methods trends analysed by using the appropriate tests. Direct counting of faecal groups with a standard- Analysis between sites would need to take into ised transect or quadrat methodology is the easiest account habitat differences; this can be assessed method to apply. Faecal counts can only be used to by plotting number of nest sites with each provide population estimates if animals can be habitat factor, such as sward height, and fitting assumed to be defecating at random within the regression lines. survey area. In many deer species, animals use It is important to standardise the survey between their home range differentially, but do appear to both visits and counts to reduce bias caused by an defecate at random within certain strata. These uneven distribution of sampling effort. Be aware strata need to be defined and mapped as a preli- also that counts may not be comparable within or minary to fieldwork and usually relate to easily between sites if there are significant differences in detected vegetation types. Faecal counts can then the topography or vegetation, as this may affect the be undertaken within each stratum to provide esti- ability to detect sites. mates of density (such as deer days of occupancy). Analysis of mark–recapture data in association Subsequently, estimates for each stratum can be with artificial nest box monitoring is dealt with in added to provide an overall estimate. It is possible Section 10.11. to analyse such data statistically to provide standard errors and confidence limits (Ratcliffe & 26.3.2 Faecal pellet counts Mayle, 1993). Circular, square or rectangular plots, transects Principles and nearest-neighbour (plotless) methods can be Faecal pellets can be used for identifying many used to estimate faecal density. In addition, there mammal species. However, Western Polecat is a choice between measurement of the standing Mustela putorius, feral Ferret M. furo and Mink crop from a single visit or the assessment of the M. vison scats can be easily confused, and different rate of accumulation of faeces by clearing faeces ungulate and lagomorph species can also be easily from plots and counting faecal accumulation after misidentified in this way. This is especially so if a period of time. there are a number of similar species occupying These choices are to some degree arbitrary and the same area. dependent upon user experience, habitat type and Many species, particularly carnivores, use their personal preference, especially when considering droppings to communicate with other individuals, plot shape. However, all methods have benefits and for instance in territory marking. Faecal pellets are difficulties. The benefits can be maximised and the therefore not distributed at random, particularly difficulties minimised by using transects to detect during the breeding season. Carnivores and insec- and measure low population densities (c.1–3 deer tivores also defecate at lower rates than herbivores. per 100 ha), standing crop for plots with medium Because of these constraints, faecal counts for densities (c.4–25 deer per 100 ha) and clearance carnivores and insectivores can usually only be plots for high densities (more than c. 25 deer per used to provide information on presence–absence 100 ha). The clearance method is more labour- and data for distribution mapping. intensive and is only worth while if the faecal den- Herbivores produce relatively large amounts of sity is known to be high. faeces and many appear to defecate at random within particular types of habitat. These factors enable estimates of population size and habitat Standing crop use to be made for these species. Faecal pellet Standing crop methods use nearest-neighbour counts are one of the most commonly used meth- techniques or quadrats to estimate faecal density ods for assessing abundance of deer populations and rely on the assumption that there is a stable (Staines & Ratcliffe, 1987; Ratcliffe & Mayle, 1993). relationship between the number of pellets 26.3 Indirect methods 457

present and the number of animals. To estimate into contact with the urine of some mammals, population size both defecation and decay rates particularly rats. Care should be taken to avoid are taken into account. Only a single visit to the unnecessary handling of faeces, and if you think site is necessary. For a full account of this method you may be at risk refer to the appropriate govern- see Ratcliffe & Mayle (1993). ment health and safety guidance.

Assessment of the rate of accumulation Data analysis and interpretation or clearance plot methods Standardised faecal counts can provide a useful Clearance plot methods use a standardised quadrat measure of relative densities of a species between methodology but the plots are cleared between sites or over time by comparing changes in the successive surveys. Because the time interval counts. An index of abundance of some species between clearance and assessment can be chosen, (Strachan & Jefferies, 1993) can be calculated if it is possible to ensure that decay is not occurring the time spent searching is standardised to reduce during the interval. This eliminates the need to bias that may occur because of an uneven distribu- measure decay rates. An optimum time interval tion of effort. can be calculated from site-specific decay rates. Droppings of some species are often highly The method is time-consuming, requiring the aggregated and have been shown to fit a negative marking of permanent plots and repeat visits. binomial distribution (Stormer et al., 1977). The Genetic markers are now being used to identify advantage of the negative binomial distribution is individuals of some species from their faeces. that it allows the interpretation of changes in den- However, analysis is time-consuming and expen- sity and decay rate, which may reflect change in sive and can therefore only be recommended for habitat use. The fit of the data can be tested by use in research studies of small populations. The using 2 goodness-of-fit tests. field equipment needed to survey and monitor Simple statistical models can be used to estimate mammals by using faecal pellet counts is summar- population size in herbivores, which produce large ized in Appendix 6. amounts of faeces, by using standing crop or plot Although Weil’s disease, caused by infection clearance methods (Box 26.1). Although there are with Leptospira, is rare, it can be caught by coming many potential sources of error in these estimates,

Box 26.1 Estimates of population size from d ¼ defecation rate faecal pellet counts a ¼ area of the site s ¼ plot size Population density can be estimated from faecal pellet t ¼ time interval between surveys (minutes). counts using either clearance plots or standing crop methods. (B) STANDING CROP METHODS

(A) CLEARANCE PLOT METHODS mr p ¼ ; d ÀÁÀÁ m a p ¼ d s ; t where p ¼ population site m ¼ mean number of pellet groups per hectare d ¼ defecation rate where p ¼ population size r ¼ mean decay rate (number per day). m ¼ mean number of pellet groups per plot 458 26 OTHER MAMMALS

careful application can minimise them. Defecation (Sargent & Morris, 1997). The field equipment rate does not appear to be strongly influenced by required for surveying and monitoring mammals diet, although volume might be. Decay rates do by using feeding signs is outlined in Appendix 6. vary, particularly in relation to soil acidity, vegetation, invertebrate activity and weather. For this Data analysis and interpretation reason greater accuracy can be achieved if local The presence of feeding signs depends on the avail- decay rates are determined. ability of different food types, which may vary seasonally, making this method an unreliable mea- 26.3.3 Feeding signs sure of population changes. Analysis should therefore be restricted to using presence–absence data to com- Principles pare sites within and between years, but even when Many species leave conspicuous markings on food using this approach it is important to relate estimates sources or remains and these can be useful for to seasonality of food availability. Count data will providing information on the presence and distri- rarely be normally distributed, so non-parametric bution of a species, usually in conjunction with tests such as the Kruskal–Wallis test (Part I, other indirect methods. Also, assuming the rela- Section 2.6.4) should be used to analyse these kinds tionship between the number of feeding signs and of data. population size is constant spatially and between years, some indication of population trends can be 26.3.4 Bait marking gained. Signs of some species are indistinguishable from others, but signs can be used to detect squir- Principles rels, Wood Mouse Apodemus sylvaticus, Bank Vole Bait marking is used to establish territory size Clethrionomys glareolus, Field Vole Microtus agrestis, and boundaries for species that use latrines to Badger, Water Vole Arvicola terrestris, Dormouse, mark their home-ranges (e.g. Badgers). By adding deer and Mountain Hare Lepus timidus. coloured indigestible markers to suitable bait, it is possible to pick out territory boundaries. By using Field methods different coloured markers, it is possible to deter- Systematic searching for signs along transects or mine the number of social groups using an area. within quadrats will provide an indicator of presence and distribution. For some target species, it Field methods may be appropriate to clear these transects of all This survey can only be done after an initial survey debris prior to starting the study, allowing the to locate all burrow entrances and latrines has been remains to be found easily, and allowing a count completed. The optimal time for bait marking is of feeding remains over time. The specific method- when the animals are at their most territorial (for ology used will depend upon the species being Badgers, between February and April) and should surveyed and the habitat type. For example, if sur- not be attempted in mid-summer or mid-winter, as veying for signs of Water Vole, standardised trans- territorial activity is at its lowest during these per- ect sampling along linear aquatic features would be iods. Bait marking surveys should run for a mini- most appropriate. Searching for signs in this way is mum of five successive days. a simple and fairly non-invasive method, which The inert marker should be mixed with a suit- allows the survey of large areas. To aid identifica- able sticky bait, so that the animal cannot selection of the species being surveyed, comparisons tively avoid ingesting the marker. The mix should can sometimes be made between the feeding be placed in a suitable location where the target remains of other species that utilise the same species and individuals have access. This can be food source. For example, gnawed Hazel Corylus difficult, as in practice non-target species may also avellana nuts may indicate the presence of take the bait. However, with ingenuity, the target Wood Mouse, Dormouse, Bank Vole or squirrel species can be favoured by the bait placement 26.3 Indirect methods 459

(e.g. covering the bait with a heavy stone will not normally do so. Transects should be spaced restrict access to the larger mammals such as far enough apart to reduce the chance of the same Badgers). individual frequenting more than one set. If the population fluctuates annually, tracking stations Data analysis and interpretation are best used when the species is at its highest The resulting data should be mapped either into a density. Scent stations work in a similar way to suitable mapping program (e.g. a GIS package) or tracking stations but attract species by using a par- onto fair maps, showing the location of all setts and ticular scent; as for baiting, this may introduce bias bait stations, and all latrines and recovered into the survey. Appendix 6 summarises the field markers. equipment required for surveying and monitoring mammals by their tracks. 26.3.5 Tracks Data analysis and interpretation Principles Anecdotal records of tracks cannot be analysed but Track counts can be used to identify a variety of are an important source for mammal recorders and species, but are usually used in conjunction with contribute to mapping the national distribution of other methods such as counts of feeding signs and species. Track data from tracking stations are inex- droppings. Tracks can be used to identify species pensive to collect, but interpretation of the results such as deer, Rabbit, Hare Lepus europaeus, Fox, may be difficult. Estimates of relative density have Badger, Water Vole, American Mink and Otter been calculated for some species, although not in Lutra lutra. Small mammals cannot usually be iden- Britain, but the assumptions required are easily tified to species, and the quality and quantity of violated so tracks are most commonly used as a prints is dependent on a number of factors such as presence–absence measure. Activity may vary soil, snow type, environmental conditions, activity, both spatially and temporally; it is almost impos- time of day and season. sible to distinguish individuals, and the stations themselves may attract or deter individuals and so Field methods will not be visited at random. Systematic searching for signs along transects or within quadrats will provide an indication of presence and activity. However, the type of substrate is 26.3.6 Hair tubes or catchers of crucial importance when recording tracks as some media are more effective than others. Soft Principles mud and snow are ideal natural media but neither Hair tubes are lengths of plastic piping, with a is permanently or uniformly distributed across diameter similar to that of burrows or holes used sampling sites to allow for comparisons. by the target species. The inside top and sides are lined with double-sided sticky tape to trap hair of Tracking stations mammals passing through the tube. Hair tubes are A more reliable approach is to provide your own most commonly used to detect the presence of Red media such as trays of dry fine sand or an ink pad and Grey Squirrels Sciurus carolinensis and (using and blotter. Numerous designs for tracking sta- smaller tube sizes) voles and shrews. tions have been created; for more details see Macdonald et al.( 199 8). Stations should be placedField methods at intervals according to the sampling strategy, The recommended size of tube for squirrels is a e.g. along transects or known runways. The station diameter of 65 mm, approximately 150 mm in could be baited, but if using the data to calculate length, and for small mammals a diameter of abundance this is not recommended as it may 25–40 mm and 100 mm in length, depending encourage individuals to use the site that would on the target species (Sargent & Morris, 1997). 460 26 OTHER MAMMALS

Hair traps can be set up from spring onwards when is important to reduce the chance of overlooking individuals are more active. individuals, although this is less important if a dis- Larger species such as Fox and Badger often tance sampling method is used (Section 10.6). leave telltale clumps of hair on barbed wire fences Point counts (Section 10.8) are similar to trans- as they squeeze underneath. This can provide use- ect counts but the observer undertakes a timed ful distribution data. A more systematic extension count of all individuals detected from a single vant- of this approach is to use loops of multi-stranded age point. If distance methods are employed, as for strong wire inserted into the ground across run- transect counts (Section 10.6), then estimates of ways so animals will squeeze underneath. Clumps abundance can also be made. Vantage point counts of finer wire are inserted within the strands to reduce disturbance and allow larger areas to be catch the hairs. Appendix 6 lists the field equip- covered in less time. Point counts from vantage ment required for surveying and monitoring mam- points are commonly used for deer species, but mals by using hair tubes or catchers. are limited to use in hilly country (Ratcliffe, 1987). Point counts reduce the chance of overlooking indi- Data analysis and interpretation viduals, which may occur while walking, and can Although this method is relatively simple and be set up to be more representative than transect unobtrusive, data analysis for this type of survey counts would allow if the habitat is patchy. Both is restricted. This method cannot be used to distin- these types of survey should be carried out during guish numbers of individuals and it can be difficult periods when the target species is likely to be most and time-consuming to identify different species. active. Results can be used to construct distribution maps Spotlight counts are useful for species that are and if surveys are conducted annually changes in active and/or less easily alarmed at night. site use can be identified. Individuals can be detected by the light reflecting in the pupils (known as eyeshine). Observation distances vary with weather conditions and habitat, so 26.4 DIRECT METHODS the length of the spotlight beam should be checked 26.4.1 Transects (including point counts at the beginning and the end of each survey. and spotlight searches) Surveys should also be limited to times of year when the vegetation cover is low. Spotlight counts Principles can be undertaken by using either transects or Transects and point counts are useful for estimat- point counts, and are usually undertaken in con- ing numbers, particularly in low-density popula- junction with daytime counts for comparison. tions and in open habitats. The number of Brown Hares are best surveyed by using these individuals counted along a transect under pre- methods, between October and mid-January. defined conditions can be used to give an index of Mountain Hares are more easily seen in late spring relative abundance. Transects can only be used for after snowmelt but before they lose their winter conspicuous species such as Rabbit, squirrels, Hare coat. Transects are best located along contour lines and deer. Lagomorphs and deer are less easily 20–100 m apart from the top of the hill, as indi- startled at night and so spotlight counts can also viduals usually run uphill if disturbed (Flux, 1970). prove a reliable method (Barnes & Tapper, 1985). Deer that occupy open range are regularly counted by direct counts by teams of observers Field methods equipped with binoculars, telescopes and two-way Line transects involve recording all individuals radios. Counts are usually conducted in the spring detected on and to each side of the transect line, when daylength is increasing but when snow cover following a suitable methodology (for more details persists on high ground, restricting the deer to low see Sections 10.6 and 10.7). All transects must be ground. Relatively high levels of precision are often surveyed with consistent effort. Observer training achieved (see Staines & Ratcliffe, 1987). Most other 26.4 Direct methods 461

deer populations occupy woodland habitats and Britain is the Longworth trap, which is effective, population estimates are usually done by vantage but bulky. In the UK these traps are available from point or faecal counts (Section 26.3.2). The field Penlon Ltd, Radley Road, Abingdon, Oxfordshire equipment required for surveying and monitoring OX1 3PH, tel. 01235 554222. They are composed mammals by using transects is detailed in of an entrance tunnel with a trip mechanism and Appendix 6. trap door and a detachable holding box, in which bait and bedding can be placed. Cheaper alterna- Data analysis and interpretation tives are widely available from pet shops. Transect data can be converted into a density esti- Traps for larger species are also available. The mate either by estimating the perpendicular dis- most commonly used are Sherman traps, which are tance of each individual from the line or by made in the USA. These are similar to Longworth counting the number of individuals within a set traps without the entrance tunnel, and are avail- distance, which will depend on the type of habitat able in a range of sizes. They are also collapsible for being surveyed. Analysis of transect data is covered easy transport. For species of Rabbit size or greater, in more detail in Sections 10.6 and 10.7. For further wire cage traps are the most effective but provide information on models used for estimating popula- no cover or insulation for captured animals. The tion density from Hare data, consult Hutchings & Clover trap is a design with a sliding drop-down Harris (1996). door of flexible nylon netting at each end, which It is best to be cautious when interpreting the can be placed on deer runs without baiting. Deer reliability of direct count data as population stu- can also be enticed into large corrals by providing dies should guarantee a uniform effort in all areas food, but this is time-consuming and expensive. of the species distribution and this can be difficult Stoats Mustela ermineus and Weasels M. nivalis can to maintain between different habitats. be very effectively trapped live by using wooden Long-term population trends cannot be derived tunnel traps with a centrally pivoted ‘see-saw’ from direct counts by simply comparing the sample floor. If such traps are built into drystone walls population each year. It is unlikely that short-term they will often catch without bait. Smearing changes can be relied upon: the degree of inaccur- Rabbit guts on the inside of the cage will improve acy inherent in direct count data is unknown. the number of captures. Handling these small mustelids is difficult and it is usually better to anaes- 26.4.2 Trapping thetise them, especially if they are to be marked or examined. Principles The layout of traps within a survey area is import- Live trapping of mammals is generally restricted to ant in order to ensure that all individuals have an rodents and insectivores, although large species equal opportunity of being caught. Trapping webs can also be trapped. Trapping can be used to pro- can be used (see Section 10.9), but trap layout will vide information on species presence and distribu- depend on the target species. For small mammals a tion, and also provides more detailed information spacing of 10–15 m is sufficient; as a general rule, if about the population such as age, sex and health of 60% or more traps are filled on one visit, more traps those individuals trapped. Despite this, trapping is are required. Traps should be positioned flush with labour-intensive, can be expensive and is stressful the ground for ground-dwelling species, preferably to individuals. Results are also easily biased by in areas of cover. Placing traps in a location known weather conditions, sex, age and trap odour. to be used by a species, such as along runs or by a latrine site, will increase the success rate. Trap Field methods locations should be marked so they can be found The type of trap to use will depend on the target easily later. species. Small mammals are most easily trapped; Traps for many species need to be baited the most commonly used trap for these species in to encourage use and to prevent animal deaths. 462 26 OTHER MAMMALS

For small mammals, seeds and grain can be used manoeuvre the animal into a suitable position for but ‘casts’ (blowfly pupae) must also be included handling. Small mammals can be gently held by for insectivores such as shrews. They can consume the scruff of the neck. 80–90% of their body mass per day (more if lactat- It is best to obtain some specific advice before ing) so a suitable amount of casts must be provided starting a trapping programme, and practical (i.e a handful). Bedding should also be provided, experience is needed of the techniques used prior and traps laid to ensure that this will not become to commencing a trapping survey. The equipment waterlogged should it rain. As high mortality rates required for surveying and monitoring mammals for shrews can occur when trap checking is infre- by trapping in the field is listed in Appendix 6. quent and insufficient food is provided, a licence must be obtained to deliberately trap shrews, Data analysis and interpretation and any protected species. If a trapping programme If mammals are being caught as part of a mark– is planned, consult the licensing section within recapture study, refer to Sections 10.11 and 26.4.3. the relevant government department to check If not, a simple calculation of mean number of indi- whether licences are needed. viduals caught per trapping occasion can be used to Traps should be checked at least every 12 hours compare numbers between years. This method will or more frequently depending on the species. only provide a population index as it is unlikely that Shrews are particularly susceptible to stress, star- all individuals in the population will be caught. vation and cold so traps should be checked every Depending on the methods used, standard statis- 3–4 hours if there is a likelihood that they may be tical tests may be applicable (Part I,Section2.6.4). caught. Otherwise, the best time to check traps is morning and evening. Some species are neophobic 26.4.3 Trapping and mark–recapture (frightened of new objects), so a short period of pre- baiting may be required to allow individuals time Principles to familiarise themselves with the traps. This is Mark–recapture studies can be used to establish when the trap is baited but not set so individuals the ratio of recaptures to newly captured individ- are free to enter and leave the traps. For small uals, which can be used to estimate population size mammals, except Field Voles, this is not necessary. (Section 10.11). It will also provide further demo- The minimum length of a trapping programme, graphic information such as immigration and dis- excluding pre-baiting, should be 3 consecutive persal rates. days or nights, longer if individuals are reluctant Mark–recapture studies will generally provide to enter the traps. The location of traps should be the most precise estimates of population size but carefully noted, and possibly marked with canes. such studies are labour-intensive and costly and are Traps should never be left out or lost. For further usually only used in research and not for EIA work. information on small mammal trapping, consult Gurnell & Flowerdew (1995). Field methods Handling any animal can be difficult without Mark–recapture studies follow the same basic practice; gauntlets are required for larger species. methods as do simple trapping programmes (see A ‘dog-catcher’ (a rope or wire noose, which is Section 26.4.2). However, traps should generally be threaded through a long metal tube or pipe) allows laid out on a grid (or along watercourses for semi- Foxes and Badgers to be handled at arm’s length aquatic species) to standardise the survey. The suc- and held prior to examination. A cotton or hessian cess of the study will also depend on the accuracy sack is useful for handling squirrels and Rabbits; a of the marking strategy. Some mammals can be large polythene bag is better for small mammals. identified by distinctive markings, such as the The contents of a sprung trap can be gently tipped throat markings of Mink. Species that cannot be into the sack to stop the animal escaping. This recognised in this way require some permanent reduces stress to the animal and enables one to marking. 26.4 Direct methods 463

Short-term studies can employ the use of fur Labtrac Ltd., Holroyd Suite, Oak Hall, Sheffield clipping, in which each individual has a small Park, Uckfield, East Sussex TN22 3QY. Different patch of guard hairs clipped at a particular site on systems are not compatible. The field equipment its body. For example, three sites from foreleg, for surveying and monitoring mammals by trap- flank and hind leg on each side, three down the ping and mark–recapture is summarized in centre of the back and one on the head provides ten Appendix 6. individual marks. Doubling up of these can add to the number of available combinations. However Data analysis and interpretation this is only useful for up to 4–6 weeks before the There is a considerable amount of literature devoted fur grows back. Semi-permanent vegetable dyes are to the analysis of mark–recapture data. This has also very effective. been briefly reviewed in Section 10.11. It is import- Larger mammals such as Rabbits and deer can be ant that the assumptions of the model chosen ear-tagged. However, large coloured ear tags, are met in order to provide an accurate population which are visible at a distance, are frequently estimate. If using a trapping web (see Section 10.9), chewed off by other animals. Only the relatively edge effects must be taken into account. Relatively obscure metal tags are more permanent, but these more animals will be trapped on the edges of the are not easy to see from a distance. Smaller tags web because individuals outside the web will be have been used on small mammals with limited attracted in. These effects are not usually accounted success; small mammal ears appear too fragile to for in the analysis and so you should be aware that hold a tag. Individually numbered Monel tags for the catchment area is underestimated and so the use on laboratory rats (National Band and Tag Co., population density will be overestimated. Newport, Kentucky, USA) can be used, or individually labelled medical metal sutures can also be used 26.4.4 Mortality data methods as ear tags. Plastic or leather collars with different coloured patches on them provide a very useful Principles means of individually marking medium to large Mortality data primarily come from game bag or species (Foxes, Badgers, deer). Radio transmitters culling records. Records can be used to determine can also be attached to these to provide informa- trends in population size, and distribution tion on range use and activity (Biotrack, Wareham, (Hutchings & Harris, 1996). There are a number of is the only company in Britain making and supply- methods of using mortality data to estimate vari- ing radio collars and receivers). With larger species, ous population parameters. Population size can be which can be easily observed in the wild, the recap- estimated from the changes in sex ratio during a ture phase is often replaced by observation. hunting season, or by using the age and sex of all A more recent method involves inserting PIT individuals that die, if this information is known (passive integrated transponder) tags just under for every year. These methods can be used for all the skin. These tags have a unique number, which species with bag records. However, species that have can be read with a scanner upon recapture. This been regularly culled at the same site for numerous method is permanent and effective but is expen- years will provide more reliable information. sive and not suitable for mammals smaller than Rabbits without their being generally anaesthe- Field methods tised first. Invasive methods such as this require a Data are already available from many hunting Home Office licence under the Animals (Scientific estates. However, the quality of information varies Procedure) Act 1986. PIT tags cost £3–£5 each, and between them; the rate of kill is rarely standardised scanners cost between £300 and £1000. They are between years and depends on the number and available from Trovan, UK ID Systems Ltd, Riverside activity of gamekeepers, changes in land use and Industrial Park, Preston, Lancashire PR3 0HP; Fish weather conditions. In addition, carcasses from Eagle Co., Lechlade, Gloucestershire GL7 3QQ; and natural deaths are not always found and recorded. 464 26 OTHER MAMMALS

Data analysis and interpretation the older droppings stamped flat. Territories Bag density is calculated as the number of animals are marked by latrines, so the densities of these killed per square kilometre per year per estate. can be taken as an indication of Water Vole These data can be used to provide an index of population size. abundance from the number killed per hectare A Water Vole survey should be confined to the per year and can be compared between years optimal period of finding breeding territories, and sites. which are marked by latrines. This period is from Population size can be determined from the late April to July. However, signs can be recorded observed change in the sex ratio before and after up until the end of September. Water Voles cannot a hunt. The number of each sex culled is recorded be accurately surveyed between October and and the population size that is consistent with the March, as their activity is significantly reduced dur- changes in the sex ratio is determined. This method ing this time, consequently leaving little sign of is susceptible to observational bias, but if the bias their presence. remains constant between years, it can provide All areas of potential Water Vole habitat on a site a reliable estimate. and any in the near vicinity beyond the site bound- Retrospective estimates of population size can ary (e.g. a drainage ditch that links with habitat be gained from cohort analysis. This is based on within the site boundary) should be included in recovering most animals that die (as can be the survey. In a linear habitat (i.e. river or canal) achieved for some deer populations). The age of the site can be divided into 500 m sections of each animal recovered is determined and thereby bank (i.e. 250 m upstream and 250 m downstream related to the year of birth. As information is accu- of a mid-point grid reference); a more three- mulated over a period of years, particular cohorts dimensional habitat (e.g. a series of drainage can be reconstructed to provide counts of the mini- ditches on a grazing marsh) can be surveyed by mum number of animals born in a particular year. each ditch, the length of which should be mea- This can then be related by birth rates, fecundity sured accurately. Where possible banks should be measures, etc. to give a population estimate inspected from the river or ditch rather than from (Ratcliffe, 1987; Staines & Ratcliffe, 1987;Ratcliffe& the bank top as this increases the probability of Mayle, 1993). This method is sometimes used to detecting signs. Approximately 45–60 minutes is assess the accuracy of population estimates calcu- required to survey each 500 m section of bank. lated by other methods, such as faecal counts. Basic survey methods follow those given in Strachan (1998). A list of essential equipment is shown in Appendix 6. All signs of Water Voles are 26.5 REQUIREMENTS FOR SPECIES recorded from both banks of the river, stream or OF PARTICULAR CONSERVATION ditch, including: IMPORTANCE * visual sightings or sounds of voles entering the This section includes the UK Biodiversity Action water; Plan species (Water Vole, Otter, Red Squirrel, * latrines; Brown Hare and Dormouse) and Badger, included * tunnel entrances; owing to its particular status in UK law (in respect * ‘lawns’ around tunnel entrances; of welfare issues) and its importance in EIA studies. * feeding remains of chopped vegetation; * paths and runs at waters edge or in vegetation; 26.5.1 Water Vole * footprints in mud.

The prime method of surveying for Water Voles is The number of vole latrines counted at a site gives to survey for field signs such as latrines and grazed an indication of the density of the Water Vole col- ‘lawns’. Latrines are characterised by accumula- ony. Larger and more robust populations show tions of droppings in a particular site, often with greater densities of closely packed latrines. When 26.5 Requirements for particular species 465

vole populations are small and fragmented, there and can only be used for assessing presence– are fewer maintained latrines. In this situation absence and for mapping distributions (Jenkins & feeding signs and burrows are often the most use- Burrows, 1980; Kruuk et al., 1986). CEH have devel- ful indicators of their presence. oped a model for Shetland, which links population To estimate numbers of adult and juvenile Water density to the number of holts. It should be borne Voles from the numbers of latrines found in the sur- in mind that in transient or low-density popula- vey, the regression to use (from Morris et al., 1998)is: tions sprainting levels are known to greatly underestimate the activity or distribution of the species. y ¼ 1:48 þ 0:683x; It is particularly important that surveyors are where y is the number of Water Voles and x the experienced, as signs are easy to overlook, and number of latrines. this can also result in an underestimate of species This equation may not be applicable to all habi- distribution. tat types and situations where Water Voles occur. Other survey methods have been tried and The number of Water Vole field signs in each tested and have been generally unsuccessful. discrete survey section should be ranked as abun- Trapping is difficult and time-consuming, making dant, frequent, scarce or none. This is done primar- mark–recapture studies unreliable. However, if a ily by the number of latrines, or by feeding signs or captive population is being reintroduced transpon- burrows in more fragmented populations. ders can be fitted so that the activities of individuals can be studied by using radio tracking. Research has been undertaken on DNA finger- 26.5.2 European Otter printing of Otters from spraints to identify individuals. This has been successfully used; although it As Otters are protected species, surveying requires is expensive, it has the advantage that it can often a licence, which can be obtained from the relevant yield a better estimate of the numbers of individual government department. Surveying only for Otter animals and local population turnover. faeces (spraints) does not require a licence. Information on Otter distribution and status can Field signs such as feeding remains, faecal depos- be gained from road kills, as this allows informa- its, tracks and holts can be searched for following tion to be gathered on an individual’s age, sex and a standardised transect methodology. Counts of health. This can also give an indication of areas that spraints provide the most reliable measure of species could be targeted for more detailed surveys. distribution. Spraints are usually deposited on pro- montories, outside holts and at entry and exit sites 26.5.3 Badger from the water. They have a characteristic sweet smell (similar to that of jasmine tea) when compared Badgers are fully protected under the Wildlife with the rather pungent smell of some other carni- (Northern Ireland) Order 1985; therefore any sur- vore scats. This allows them to be easily distinguished vey which may interfere with the animals or their from scats such as those deposited by Mink. They places of shelter must by licensed by the appropri- often contain fish scales, amphibian bones and some- ate agency. times feathers and fur. Fresh spraints are usually The optimal method of survey for Badgers is to dark green, black or grey in colour depending on search the target area and the area around it for the contents. Sprainting occurs throughout the year field signs of the species. Grassland areas should be so there is no optimal monitoring time, although surveyed for footprints, dung pits, snuffle holes peaks have been recorded in winter and early spring and distinctive runways through the vegetation. (Macdonald & Mason, 1987). Boundary hedges, walls and fences should be Although spraint surveys are the most effective searched for latrines indicating a territory bound- method for monitoring Otter populations, they do ary. Runways under boundary fences and hedges not provide a good indication of population density should be searched for stray hairs. Hedgerows, 466 26 OTHER MAMMALS

earth banks, woodland and scrub habitats should coloured markers in the faeces; it may be necessary be searched for signs of sett building activity, includ- to smear these out with a stick to locate the mar- ing dung pits and hairs close to sett entrances, kers. Should two colours turn up at one latrine, it is discarded bedding, and spoil heaps from recent dig- important to determine whether this came from ging. Sett entrances are large holes (larger than one dropping (and hence from a single individual Rabbit burrows) which can often be confirmed as with access to different bait points) or from differ- Badger holes by the presence of characteristic ent droppings (different individuals using the same guard hairs or footprints. latrine). Continue searching for new latrines dur- Setts found should be examined to establish ing the survey period. their level of usage. Each hole should be classified under one of the following categories defining use. 26.5.4 Dormouse * Well used: An entrance free of leaf litter and show- Dormice are fully protected under Schedule 5 of ing recent signs of excavation. the Wildlife & Countryside Act 1981, as updated * Partly used: An entrance with some leaf litter and by the Countryside and Rights of Way Act 2000. debris around the hole but also showing some Dormice are also included on Schedule 2 of the signs of recent digging. Conservation (Natural Habitats etc.) Regulations * Disused: An entrance with debris and leaf litter 1994 as a European protected species. partially obscuring the hole with no recent signs Potential Dormouse habitat comprises: of digging; or a hole that exhibits the characteristics of a Badger hole (with a large, D-shaped * Woodland with a dense understorey; entrance and old spoil piles at the entrance), but * Coppice woodland; shows no other signs of Badger activity. * Overgrown hedgerows; * Conifer plantations (less likely); The optimal time for survey is February to April * Reed beds (less likely). when territories are most actively marked. Surveys can be undertaken at other times of year The presence of Dormice can be recognised from but signs of activity will be fewer, particularly over field signs. Gnawed Hazel nuts can provide positive winter when Badgers may stay underground for confirmation of Dormouse presence; the hole in days at a time if temperatures are low. the nut shell will have a smoothed edge, unlike In addition, bait marking surveys are a very use- shells opened by mice and voles, which have trans- ful method of determining badger clan territories, verse tooth marks across the cut edge of the shell. and establishing whether different setts are used Obviously, this is only possible if fruiting Hazel by the same group, or by two different social trees are present; even if extensive searches are groups. The protocol is as in Section 26.3.4 above. made for nuts eaten by Dormice, the presence of To prepare the bait and marker mix, add around Dormice cannot be ruled out if none are found. half a litre of inert marker (2 mm pellets of the raw This survey methodology is not described in detail, material for plastic injection moulding) to around 7 but see Section 26.3.3. To obtain more detailed litres of peanuts and/or cereal in a large bucket. survey information on distribution and numbers, Once they are well mixed, gently pour 1 litre of a survey using nest boxes or nest tubes is required. syrup over the mix and leave overnight for the Wooden nest boxes can be obtained from local syrup to seep through. Place the bait in small mammalgroupsortheWildlifeTrusts.Theentrance scrapes covered by a stone or log (to keep rain and is at the back of the box, facing the tree, with spacing other animals from the bait) near the sett bars above and below the hole. The hole should be entrances, around 20–30 scrapes per sett to allow approximately 35 mm in diameter but the dimen- all sett members access to bait. Where two or more sionsoftheboxitselfarenotcritical.They setts are being marked, use different coloured mar- should be approximately 120 mm wide 120 mm kers for each sett. Carefully check each latrine for deep 200 mm high. The top should slide off, 26.5 Requirements for particular species 467

rather than being hinged to the box, to make it in these conditions can jeopardise their survival; easier to check inside without the animals escaping. their fur is not waterproof so they can become Nest tubes are available from The Mammal chilled, leading to critical losses of fat reserves. In Society. These consist of a wooden tray and a plas- light rain, or cold but dry weather, the surveyor tic tube. The wooden tray fits inside the tube and should make a judgement with regards to whether seals one end. or not to carry out the survey. In these situations, A minimum of 20 boxes or tubes should be put reducing handling and disturbance can lessen out, and they should ideally be placed approxi- adverse effects on the animals. mately 20 m apart throughout all potentially suita- When initial inspection of the box or tube leads ble habitat on the site. They can be attached to trees the surveyor to suspect that Dormice may be of any species, but those well-linked to the under- inside, the hole in the box or front of the tube storey are most suitable. All boxes and tubes should should be blocked with a plastic bag and the box be numbered. or tube should be taken down and placed in a large Both boxes and tubes should be attached to trees plastic cement bag on the ground. Note: only one with plastic-coated bell wire. Tubes should be carrier bag ‘stuffer’ should be taken on the survey attached to horizontal branches, or branches lean- to avoid confusion about whether boxes or tubes ing downwards slightly, so that water does not have been put back with the hole blocked by a bag. accumulate at the end. The lid of the box or tray of the tube should be The height of boxes and tubes on the tree is not carefully and slowly removed. important, other than to ensure that they are easy If the surveyor is unsure whether the box is for the surveyor to check. Boxes and tubes should inhabited by Dormice or other small mammals, a be sited away from footpaths and where possible stick should be used to gently move the nest or should not be visible to the public. leaves in the box. Wood Mice and Yellow-necked Boxes should be put out by March of the year in Mice Apodemus flavicollis may bite, but Dormice very which the surveys will commence. Tubes should be rarely do. put up by July of the year in which the surveys will Careful note should be taken of the behaviour of commence. Tubes can be put out later in the year the Dormouse inside the box in the breeding sea- than boxes because tubes are primarily used by son (typically July to September, but varies accord- dispersing juveniles, born in that season. These ing to the weather) because nests with babies individuals typically do not leave the maternal should not be disturbed; furless young are vulner- nest until late summer or early autumn. able to the cold and new mothers can become dis- Boxes need to be checked once per month from tressed if handled. If the Dormouse sits still in the May through to October (inclusive). They should box when the lid is removed and slight disturbance not be checked any less frequently as temporal to the nest is made, the box should be put back and changes in Dormouse behaviour could result in a note of a likely breeding nest made. Dormice being missed if they use the box for a Once Dormice have been counted, the lid should short time and do not make a nest. They should then be put back on the box and the ‘stuffer’ not be checked any more frequently as this could removed. Dormice should then be carefully caught cause unnecessary stress to the animals; when they and encouraged to re-enter the box through the are woken from torpor they use up valuable fat hole. With tubes, the ‘stuffer’ should be removed reserves. from the front of the tube and Dormice caught and Tubes should be checked once per month from encouraged to re-enter. The hole or front is then the month they are put out, through to October re-blocked while the box or tube is placed back on (and also early November if the weather is mild). the tree. Any notes should be made and all equip- Nest boxes and tubes must not be checked when ment packed away before the ‘stuffer’ is removed the weather is both cold and raining. Surveys and the surveyors leave the vicinity of the box or should be re-arranged because disturbing Dormice tube quietly. 468 26 OTHER MAMMALS

For the purposes of determining presence – Spring and autumn are the times of year when the absence and distribution it is not necessary to squirrels are most active and visible, and therefore weigh and sex individuals, but a count of individ- the optimal times for survey. Surveys should be uals in each box is useful. The nest (if present) done in the early morning and late afternoon, and should be carefully examined and lifted out of the not be undertaken in periods of rain, strong wind box or tube to enable a count. If translocation of or cold weather. A standardised method of survey is Dormice is a possibility, it may be beneficial to in use in areas of Scotland. This consists of a mix of obtain information about their body mass and transect counts and point counts; a transect of 10 m population dynamics through weighing and sexing is walked slowly, taking around 5 minutes, fol- individuals. This information can be valuable for lowed by a point count of 3 minutes, etc. A kilo- research into Dormouse behaviour and population metre of woodland can be walked in 1 hour and 20 dynamics. For weighing, Dormice must be trans- minutes (Ayrshire Red Squirrel Group, 2004). ferred to a plastic sandwich bag and weighed on a Monthly transect counts of Red Squirrels can portable spring scale (max. 50 is sufficient). provide a reliable index of population size, but Positive confirmation of Dormouse presence can this regular monitoring requires a dedicated team be obtained from nests only. This is because of volunteers. For details of this contact the UK Red Dormouse nests are distinctive and, although they Squirrel survey co-ordinator (Northumbria Wildlife could possibly be confused with Harvest mouse Trust; tel. 0191 2846884). Micromys minutus nests, Harvest mice are very unli- Hair tube surveys can also be done, and will also kely to be present in Dormouse habitat. Dormouse distinguish between Red and Grey Squirrels nests can be distinguished by a centre woven (Gurnell et al., 2001). The hair tubes should be from grass or strips of Honeysuckle Lonicera pericly- approximately 6.5 cm in diameter and around menum bark. The outer layer can be made of green 30 cm in length, and contain a detachable block leaves, but this is not always the case as nests have with double-sided sticky tape attached to either been found with dead leaves on the outer layer. end of the interior of the tube. The recommended The location of boxes and tubes should be density for red squirrels is 20 at 100 m intervals. marked on a map of the site, with boxes or tubes These tubes should be placed along the upper side with evidence of Dormice highlighted. If additional of a branch and baited with sunflower seeds, pea- data on numbers, body mass and sex are recorded, nuts or corn. The tubes should be checked every these should be displayed in a table. See Bright et al. 7–14 days (Gurnell et al. 2001). Hairs can then be (1996) for further details. identified through cross-reference with identified samples or from keys, using a reflected light micro- 26.5.5 Red Squirrel scope. Only guard hairs (the outermost longest hairs) can be used for identification. Ninety-five Red Squirrels are fully protected under the Wildlife & percent of guard hairs with a groove running the Countryside Act 1981 and the Wildlife (Northern length of the transverse section can be confirmed Ireland) Order 1985; any survey that may interfere as Red Squirrel. This can be observed by using with the animals or their places of shelter must reflective light and a dilute ink solution and a sui- therefore be licensed by the appropriate agency. tably powered microscope. Unfortunately, hair col- A variety of non-intrusive methods to survey for our cannot be relied upon. squirrels are available; however, some of these can- Other non-intrusive methods that cannot reli- not be used to differentiate between Red and Grey ably separate Red from Grey Squirrels include Squirrels. Good sources of further information are drey counts and feeding transects. Drey counts con- the references by Gurnell et al. (2001, 2004). sist of systematically surveying woodlands for Direct survey methods that can be used are intact dreys. Where it can be certain that these transect counts and spot counts, the principles of belong to Red Squirrels (i.e. where Grey Squirrels which are outlined in the methods section above. are absent) the number of Red Squirrels can be 26.6 Mammal conservation evaluation criteria 469

calculated by using the following equation (calcu- stationary, at a position chosen for its vantage lated for data collected in winter): point over surrounding hare habitat. These surveys Number of Red Squirrels per ha ¼ number of should be done from dusk onwards. dreys per ha 0.26. Feeding transects should be Walked transects in daylight hours are under- cleared prior to survey: a recommended size is taken for the national Hare survey. The most appro- 50 m 1 m. These should be visited at regular inter- priate survey technique is to use line transect vals. The presence of stripped cones indicates the sampling. On average transects in the national presence of squirrels (cannot differentiate between Hare survey are three kilometres long around a Red and Grey). The data can be used to estimate one-kilometre square. Each transect is walked squirrel density (if only one species is present) by three times, once a month between mid-October calculating the amount of energy being consumed and mid-January. The survey is stratified by using by squirrels in the woodland over time, and divid- the Institute of Terrestrial Ecology’s (now CEH’s) ing that by the average energy consumption of four land class groups. squirrels. A full description of the method can be found in Gurnell et al. (2001), with average figures 26.6 MAMMAL CONSERVATION for squirrel energy consumption and seed energy EVALUATION CRITERIA content. This method can only derive approximate density figures. Key evaluation considerations Trapping should use single catch traps, placed in a suitable sheltered location. These should The recently formed ‘Tracking Mammals be checked regularly; as this is a method requir- Partnership’ aims to monitor the population of ing handling skills and causing some distress to a mammal species in the UK; certain programmes protected species, further information should are already under way (e.g. the national Otter sur- be sought from the relevant agency and from veys). Further details can be found at http:// Red Squirrel groups (e.g. Northumbria Wildlife www.jncc.gov.uk/species/mammals/trackingmam- Trust, Red Alert (http://www.redsquirrel.org.uk/)). mals/default.htm. A licence is also required. It is illegal to re-release any Grey Squirrels accidentally caught as part of Protection status in the UK and EU the trapping effort. Many of the mammals in Great Britain are afforded legal protection under the Wildlife & Countryside 26.5.6 Brown Hare Act, replaced in Northern Ireland by the Wildlife Large-scale monitoring and survey for Brown Hares (Northern Ireland) Order 1985, the Nature can gain very useful data from game bag records, Conservation and Amenity Lands (Northern where these are available. As highlighted above, Ireland) Order 1985 and the Conservation (Natural there are limitations to these, and they are only Habitats & c.) Regulations 1994. Legal protection is available where gamekeepers are active. also afforded by the Bern Convention, the One method is to use night surveys. These can Convention on International Trade of Endangered be driven transects (see for example, Preston Species of Wild Fauna and Flora (CITES) and the EU et al., 2002b) or spot counts from parked cars Habitats Directive. (Tapper, 2001). For the driven transects, a 4-wheel The degree of protection afforded varies consid- drive vehicle with a viewing deck is used, allowing erably, but is a function of the animal’s rarity, one person to stand upright, scanning the sur- status (native or introduced), and use by people. rounding area for hares with a powerful torch, Restrictions on planning and development that while the vehicle is moving. The vehicle is driven may affect protected species are conducted at approximately 15 km h1. The point count uses a through DEFRA’s Planning Policy Guidance on similar technique, but surveyed while the vehicle is Nature Conservation (PPG9) in Great Britain. 470 Table 26.2. Summary of applicable conservation legislation and status of mammals in the UK

Scientific EU Bern UK Act NI Order BAP Conservation Name Name Annex App. Schedule a Schedule Priority Status b

Water Vole Arvicola terrestris 4a, 4b P c Major long term decline Wild Cat Felis sylvestris IVa II 5 Once found throughout mainland Britain, now confined to parts of Scotland Grey Seal Halichoerus grypha II 5 European Otter Lutra lutra IIa, IVa II 5 5 P Widespread in 1950s, twenty years later had disappeared from most of England and Wales; population slowly increasing Pine Marten Martes martes 5 5 Once found within 30 miles of London, now largely confined to remote areas in Scotland Badger Meles meles 5 Protection of Badgers Act (1992) Dormouse Muscardinus avellanarius IVa 5 P Has disappeared from half the range it occupied during the nineteenth century Walrus Odobenus rosmarus II 5 Common Seal Phoca vitulina IIa 5 Population has declined since the 1988 outbreak of phocine distemper Red Squirrel Sciurus vulgaris 5 5 P Extinct over most of England and Wales Brown Hare Lepus europaeus P Showing signs of a general decline associated with intensification in farming Polecat Mustela putorius Once widespread but now extinct in Scotland and most of England Mountain Hare Lepus timidus Locally vulnerable, especially the isolated, small (and only) English population in the Peak District

a Full protection except Water Vole. b Source: Mammal website factsheets of UK endangered mammals (www.abdn.ac.uk/mammal/endanger.htm). c P, Priority BAP species. 26.6 Mammal conservation evaluation criteria 471

Species-specific regulation to be aware of is the concern are subject to Species Biodiversity Action Badgers Act (1992). Certain animals are UK Plans and/or protected by UK or EU legislation. Biodiversity Action Plan species and/or Local Guides for Britain include Harris et al. (1995), Biodiversity Action Plan Species. The Species Macdonald & Tattersall (2001)andJNCC(1994); for Action Plans for Northern Ireland are in the process Ireland (including Northern Ireland) the Irish Red of being completed. Data Book 2: Vertebrates (Whilde, 1993). At the time of writing, up to date species lists for these pieces of legislation can be obtained from the Site designation criteria following websites: Areas may be considered of international importance * www.cites.org/eng/resources/species.html. Species if they contain a nationally important population of protected from international trade through Otters,asthisisaEuropeanProtectedspecies. CITES. The selection criteria for nationally important * europa.eu.int/comm/environment/nature/habdir. sites for mammals (other than bats or marine mam- htm. The EU Habitats Directive, with links to the mals) are the guidelines for the selection of SSSIs different Annexes. (NCC, 1989). For the Otter, in England and Wales, * www.nature.coe.int/english/cadres/bern.htm. The breeding holts and their surroundings may be con- website for the Bern Convention. sidered of national importance. As other mammal * www.ukbap.org.uk/. Lists the local and UK species are so widely dispersed, the occurrence of Biodiversity Action Plan species. Pine Marten, Wild Cat Felis sylvestris, Polecat Mustela * www.hmso.gov.uk. Contains the UK and Northern putorius, Red Squirrel, Common Dormouse, Yellow- Ireland legislation. necked Mouse, Orkney Vole Microtus arvalis or Scilly * www.ehsni.gov.uk/natural/legs/legs.shtml. Shrew Crocidura suaveolens are all considered as Contains links to the wildlife-related legislation of elements that enhance the value of a site on the Northern Ireland. national scale. Table 26.2 provides a summary of the applicable At the county level, any locally significant popu- legislation and conservation status of selected lation of a mammal species that is listed in a mammals in the UK. County or Metropolitan Red Data Book or Local or National Biodiversity Action Plan species on Conservation status in the UK account of its regional rarity or localisation is considered of county importance. The status of UK mammals ranges from rare (e.g. At levels lower than this, the approach described Pine Marten Martes martes)tointroducedpestspecies in Chapter 3 of this Handbook (based on IEEM 2002 (e.g.BrownRat).Thespeciesofmostconservation guidelines) should be referred to.

Appendix 1 Monitoring and reporting obligations under international conservation agreements Adapted from Shaw & Wind (1997).

# RPS Group plc and Scottish Natural Heritage 2005. 2 years 10 years 3 years Frequency 5 years Reporting to: The Secretariat (UNEP) UNESCO World Heritage Centre Man and the Biosphere Programme (UNESCO) The Ramsar Bureau (IUCN) ad interventions, Purpose of monitoring To assess trade levels and changes in species’ status Improved site management, advanced planning, reduction of emergency and hoc and reduction of costs through pre- ventative conservation To assess change within a network of baseline and monitoring stations in representative undisturbed biome areas To detect a change in ecological character undertake ... scientific & technical studies’ toring and reporting’conditions of the site to be recorded every year ‘monitoring’ informed’, ‘research’ and ‘the exchange of data’ ‘review progress ‘arrange to be Requirement to monitor Terms Site- based? No Implied Yes Confirmed ‘systematic moni- Yes Confirmed ‘inventory’ and Yes Implied To identify formations of outstanding aesthetic, conservation or scientific importance, and to develop methods to counter- act dangers to cultural or natural heritage To regulate international trade in endangered species To promote wise use of all wetlands and to provide protection for wetlands of international importance To improve links between people and the biosphere through the preservation of ecological and genetic diversity with consideration of the local economy, and of research, monitoring and training activities CITES, 1973 The World Heritage Convention, 1972 Agreement Main aim Global The Ramsar Convention, 1971 Man and the Biosphere Programme, 1971

474 The Bonn To ensure strict pro- No Confirmeda present ‘evidence’ To determine the Bonn 3 years Convention, tection of migratory of status; ‘monitor’ status of species Convention 1979 species in danger of measures taken and the effective- Secretariat extinction through- ness of measures (UNEP) out all or a significant taken portion of their range The To identify important Yes b Confirmed ‘Monitor,through To determine Conference of To be determined Convention components of and sampling ... biolo- levels of biodiver- Parties (UNEP) on Biological processes affecting gical diversity’ sity and identify Diversity, the sustainable use of processes having 1992 biological diversity; significant adverse their monitoring; eco- impact system management; and the regulation of biological resources European European To encourage the Yes Implied ‘on-the-spot To detect danger of Council of Annual (self- Diploma, effective protection of appraisal’ a serious threat ... Europe assessment); 5 yearly 1965 certain landscapes, serious deteriora- (independent reserves and natural tion and the effec- assessment) features of European tiveness of existing interest precautions Biogenetic To establish a Yes Implied ‘biological To determine Council of Not specified Reserves, European network of research’ and whether long-term Europe 1975 reserves that guaran- ‘maintain and ... measures have tee the biological bal- enhance target maintained or ance, genetic diversity features’ enhanced the and representative- potential and the ness of habitats con- diversity of the sidered typical, protected features unique, rare or 475 476

Table (cont.)

Site- Requirement Purpose Reporting Agreement Main aim based? to monitor Terms of monitoring to: Frequency endangered, for biological research, training and education Birds To maintain bird Yes Implied ‘Trends and varia- To determine The European 3 years Directive, populations at levels tions’ ‘ ...taken whether bird Commission 1979 corresponding to eco- into account’ populations are logical requirements maintained at and to regulate trade, levels correspond- hunting, exploitation ing to ecological and methods of cap- requirements ture and killing Bern To conserve wild flora No c Implied Not specified To determine The Standing 2 years Convention, and fauna and their whether species Committee 1982 natural habitats, giv- have attained satis- (Council of ing particular empha- factory population Europe) sis to endangered and levels; whether vulnerable migratory habitats have dete- birds riorated; and the effects of derogations Habitats To contribute towards Yes Confirmed ‘surveillance’ of Determine the The European 2 years (derogations); Directive, ensuring biodiversity habitats and spe- conservation Commission 6 years (measures 1992 through the conserva- cies; ‘monitor’ status of priority taken and status tion of natural habi- incidental capture habitats and of habitats and tats and wild flora and and killing species; monitor species) fauna incidental capture and killing and its effects; and report on derogations EECONET, To develop a coherent (Yes) d Unclear Several referencesNo indication of Council of Not specified 1993 European network of to data collection, ‘monitoring’ or Europe habitats in which the amounting to an ‘surveillance’ full range of habitats inventory on requirements is represented, the which selection of most important areas core areas will be of the different habi- based tat types are included and appropriate linkages to facilitate the dispersal and migration of species are incorporated

a An explicit reference to monitoring is made, but applies to measures taken, rather than to the target species themselves. b The Convention on biological diversity proposes a variety of measures to safeguard or assess biodiversity, among them the need to ‘establish a system of protected areas or areas where special measures need to be taken to conserve biological diversity’. c The Bern Convention requires each contracting party to protect ‘areas that are of importance for . . . migratory species’. However, such areas are not formally designated under the convention. d Requires the selection of ‘core areas’ and of corridors which link them into a habitat network. 477 Appendix 2 Relationship between BAP Priority Habitat and Broad Habitat categories and Habitats Directive nomenclature

BAP Priority Annex I Habitats Directivea Habitat code Annex I type Comment

Upland 91A0 Old Sessile Oak (Quercus petraea) — oakwood woods with Ilex and Blechnum in the British Isles Lowland Beech 91J0 Taxus baccata woods of the British — and Yew Isles* woodland Lowland Beech 9120 Atlantic acidophilous Beech for- — and Yew ests with Ilex and sometimes also woodland Taxus in the shrub layer (Quercion robori-petraeae or Ilici-Fagenion) Lowland Beech 9130 Asperulo-Fagetum Beech forests — and Yew woodland Lowland mixed 9160 Sub-Atlantic and medio-European — deciduous Oak or Oak–Hornbeam forests of woodland the Carpinion betuli Upland mixed 9180 Tilio-Acerion forests of slopes, — ashwoods screes and ravines* Upland mixed 91J0 Taxus baccata woods of the British — ashwoods Isles* Upland mixed 8240 Limestone pavements* — ashwoods Wet woodland 91E0 Alluvial forest with Alnus glutinosa — and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae)* Wet woodland 91D0 Bog woodland* — Lowland wood- 9160 Sub-Atlantic and medio-European — pasture and oak or oak–hornbeam forests of parkland the Carpinion betuli Upland —— — birchwoods Native pine 91C0 Caledonian forest* — woodlands

# RPS Group plc and Scottish Natural Heritage 2005. BAP and Habitats Directive categories 479

BAP Priority Annex I Habitats Directivea Habitat code Annex I type Comment

Native pine 91D0 Bog woodland* — woodlands Ancient and/or —— — species-rich hedgerows Cereal field —— — margins Coastal and 6510 Lowland hay meadows (Alopecurus — floodplain graz- pratensis, Sanguisorba officinalis) ing marsh Lowland 6510 Lowland hay meadows (Alopecurus — meadows pratensis, Sanguisorba officinalis) Upland hay 6520 Mountain hay meadows — meadows Lowland calcar- 6210 Semi-natural dry grasslands and — eous grassland scrubland facies on calcareous substrates (Festuco-Brometalia) (*important orchid sites) Upland calcar- 6210 Semi-natural dry grasslands and — eous grassland scrubland facies on calcareous substrates (Festuco-Brometalia) (*important orchid sites) Upland calcar- 6230 Species-rich Nardus grassland on — eous grassland siliceous substrates in mountain areas (and submountain areas in continental Europe)* Upland calcar- 6170 Alpine and subalpine calcareous — eous grassland grasslands Lowland dry 2330 Inland dunes with open — acid grassland Corynephorus and Agrostis grasslands Lowland 4030 European dry heaths — heathland Lowland 4040 Dry Atlantic coastal heaths with — heathland Erica vagans* Lowland 4010 Northern Atlantic wet heaths with — heathland Erica tetralix Lowland 4020 Temperate Atlantic wet heaths — heathland with Erica ciliaris and Erica tetralix* Lowland 7150 Depressions on peat substrates of This ‘micro-habitat’ can heathland the Rhynchosporion occur within a range of mire and heath types 480 APPENDIX 2

BAP Priority Annex I Habitats Directivea Habitat code Annex I type Comment

Upland 4030 European dry heaths — heathland Upland 4010 Northern Atlantic wet heaths with — heathland Erica tetralix Upland 4060 Alpine and Boreal heaths Heath types restricted to heathland the montane zone are not included in Upland heathland Purple moor 6410 Molinia meadows on calcareous, — grass and rush peaty or clayey-silt-laden soils pastures (Molinion caeruleae) (Molinia–Juncus) Fens 7230 Alkaline fens Lowland examples only Fens 7210 Calcareous fens with Cladium — mariscus and species of the Caricion davallianae* Fens 7220 Petrifying springs with tufa Lowland examples only formations (Cratoneurion)* Fens 7140 Transition mires and quaking Lowland examples only bogs Fens 7150 Depressions on peat substrates of This ‘micro-habitat’ can the Rhynchosporion occur within a range of mire and heath types Reedbeds — — — Lowland raised 3160 Natural dystrophic lakes and Only bog pools within bog ponds lowland raised bog systems are included Lowland raised 7110 Active raised bogs* — bog Lowland raised 7120 Degraded raised bogs still capable — bog of regeneration Lowland raised 7150 Depressions on peat substrates of This ‘micro-habitat’ can bog the Rhynchosporion occur within a range of mire and heath types Blanket bog 3160 Natural dystrophic lakes and Only bog pools within ponds blanket bog systems are included Blanket bog 7130 Blanket bogs (*if active bog) — Blanket bog 7140 Transition mires and quaking Ladder fens are included bogs with blanket bog BAP and Habitats Directive categories 481

BAP Priority Annex I Habitats Directivea Habitat code Annex I type Comment

Blanket bog 7150 Depressions on peat substrates of This ‘micro-habitat’ can the Rhynchosporion occur within a range of mire and heath types Mesotrophic 3130 Oligotrophic to mesotrophic — lakes standing waters with vegetation of the Littorelletea uniflorae and/ or of the Isoeto-Nanojuncetea Mesotrophic 3140 Hard oligo-mesotrophic waters — lakes with benthic vegetation of Chara spp. Eutrophic 3150 Natural eutrophic lakes with — standing waters Magnopotamion or Hydrocharition-type vegetation Aquifer-fed 3150 Natural eutrophic lakes with Breckland meres naturally fluc- Magnopotamion or tuating water Hydrocharition-type vegetation bodies Aquifer-fed 3180 Turloughs* — naturally fluctuating water bodies Chalk rivers 3260 Water courses of plain to montane — levels with the Ranunculion flui- tantis and Callitricho-Batrachion vegetation Limestone 8240 Limestone pavements* — pavements Maritime cliff 1230 Vegetated sea cliffs of the Atlantic — and slopes and Baltic coasts Coastal vege- 1210 Annual vegetation of drift lines — tated shingle Coastal vege- 1220 Perennial vegetation of stony — tated shingle banks Machair 21A0 Machairs — Coastal sand 2110 Embryonic shifting dunes — dunes Coastal sand 2120 Shifting dunes along the shoreline — dunes with Ammophila arenaria (white dunes) Coastal sand 2130 Fixed dunes with herbaceous — dunes vegetation (grey dunes)* 482 APPENDIX 2

BAP Priority Annex I Habitats Directivea Habitat code Annex I type Comment

Coastal sand 2140 Decalcified fixed dunes with — dunes Empetrum nigrum* Coastal sand 2150 Atlantic decalcified fixed dunes — dunes (Calluno-Ulicetea)* Coastal sand 2160 Dunes with Hippophae rhamnoides — dunes Coastal sand 2170 Dunes with Salix repens ssp. — dunes argentea (Salicion arenariae) Coastal sand 2190 Humid dune slacks — dunes Coastal sand 2250 Coastal dunes with Juniperus spp.* — dunes Coastal 1310 Salicornia and other annuals — saltmarsh colonising mud and sand Coastal 1320 Spartina swards (Spartinion — saltmarsh maritimae) Coastal 1330 Atlantic salt meadows (Glauco- — saltmarsh Puccinellietalia maritimae) Coastal 1420 Mediterranean and thermo- — saltmarsh Atlantic halophilous scrubs (Sarcocornetea fruticosi) Coastal 1130 Estuaries — saltmarsh Saline lagoons 1150 Coastal lagoons* — Seagrass beds 1140 Mudflats and sandflats not — covered by sea water at low tide Seagrass beds 1110 Sandbanks that are slightly — covered by sea water all the time Seagrass beds 1130 Estuaries — Seagrass beds 1160 Large shallow inlets and bays — Mudflats 1140 Mudflats and sandflats not — covered by sea water at low tide Mudflats 1130 Estuaries — Mudflats 1160 Large shallow inlets and bays — Sheltered 1160 Large shallow inlets and bays — muddy gravels Sheltered 1140 Mudflats and sandflats not — muddy gravels covered by sea water at low tide Littoral and 8330 Submerged or partly submerged — sublittoral sea caves chalk BAP and Habitats Directive categories 483

BAP Priority Annex I Habitats Directivea Habitat code Annex I type Comment

Littoral and 1170 Reefs — sublittoral chalk Maerl beds 1110 Sandbanks that are slightly — covered by sea water all the time Maerl beds 1160 Large shallow inlets and bays — Mud habitats in —— — deep water Sabellaria 1170 Reefs — alveolata reefs Tidal rapids 1170 Reefs — Tidal rapids 1160 Large shallow inlets and bays — Modiolus 1170 Reefs — modiolus beds Modiolus 1160 Large shallow inlets and bays — modiolus beds Serpulid reefs 1170 Reefs — Lophelia pertusa 1170 Reefs — reefs Sabellaria 1170 Reefs — spinulosa reefs Sabellaria 1160 Large shallow inlets and bays — spinulosa reefs Sublittoral 1110 Sandbanks that are slightly — sands and covered by sea water all the time gravels Sublittoral 1160 Large shallow inlets and bays — sands and gravels Sublittoral 1130 Estuaries — sands and gravels 484 APPENDIX 2

BAP Broad Annex I Habitats Directivea Habitat code Annex I type Comment

Broadleaved, 9120 Beech forests with Ilex and Taxus, — mixed and yew rich in epiphytes (Ilici-Fagion) woodland (41.12) Broadleaved, 9130 Asperulo-fagetum beech forests — mixed and yew (41.13) woodland Broadleaved, 9160 Stellario-Carpinetum — mixed and yew oak–hornbeam forests (41.24) woodland Broadleaved, 9180 *Tilio-Acerion ravine forests (41.4) — mixed and yew woodland Broadleaved, 9190 Old acidophilous oak woods with — mixed and yew Ilex and Blechnum in the British woodland Isles (41.53) Broadleaved, 91A0 Old oak woods with Ilex and — mixed and yew Blechnum in the British Isles (41.53) woodland Broadleaved, 91E0 Residual alluvial forests (Alnion — mixed and yew glutinoso-incanae) (44.3) woodland Broadleaved, 91J0 *Taxus baccata woods (42.A71 to — mixed and yew 42.A73) woodland Broadleaved, 91D0 *Bog woodland (44.A1 to Bog woodland in the mixed and yew 44.A4) p.p. New Forest consisting of woodland birch, willow and alder Broadleaved, 5110 Stable Buxus sempervirens forma- — mixed and yew tions on calcareous rock slopes woodland (Berberidion p.) (31.82) Broadleaved, 5130 Juniperus communis formations on Juniper formations on mixed and yew heaths or calcareous grasslands calcareous grassland woodland (31.88) p.p. Coniferous 91C0 *Caledonian forest (42.51) — woodland Coniferous 91D0 *Bog woodland (44.A1 to Bog woodland of Scots woodland 44.A4) p.p. pine Coniferous 5130 Juniperus communis formations on Juniper formations on woodland heaths or calcareous grasslands heath (31.88) p.p. BAP and Habitats Directive categories 485

BAP Broad Annex I Habitats Directivea Habitat code Annex I type Comment

Boundary and —— — linear features Arable and —— — horticultural Improved —— — grassland Neutral 6510 Lowland hay meadows (Alopecurus — grassland pratensis, Sanguisorba officinalis) (38.2) Neutral 6520 Mountain hay meadows (British — grassland types with Geranium sylvaticum) (38.3) Calcareous 6170 Alpine calcareous grasslands — grassland (36.41 to 36.45) Calcareous 6120 Semi-natural dry grasslands and — grassland scrubland facies on calcareous substrates (Festuco-Brometalia) (34.31 to 34.34) Calcareous 6210 Semi-natural dry grasslands and — grassland scrubland facies on calcareous substrates (Festuco-Brometalia) (*important orchid sites) (34.31 to 34.34) Calcareous 6230 *Species-rich Nardus grassland, on — grassland siliceous substrates in mountain areas (and submountain areas, in continental Europe) (35.1) Acid grassland 2330 Open grassland with Corynephorus — and Agrostis of continental dunes (64.1 Â 35.2) Bracken — — — Dwarf shrub 4010 Northern Atlantic wet heaths with — heath Erica tetralix (31.11) Dwarf shrub 4020 *Southern Atlantic wet heaths — heath with Erica ciliaris and Erica tetralix (31.12) Dwarf shrub 4030 Dry heaths (all subtypes) (31.2) — heath Dwarf shrub 4040 *Dry coastal heaths with Erica — heath vagans and Ulex maritimus (31.234) 486 APPENDIX 2

BAP Broad Annex I Habitats Directivea Habitat code Annex I type Comment

Dwarf shrub 4060 Alpine and subalpine heaths Heaths that are mostly heath (31.4) p.p. confined to the alpine zone, namely the NVC communities H13, H14, H15, H17, H19, H20 and H22, are included in the ‘Montane habitats’ broad habitat type Fen, marsh and 6410 Molinia meadows on chalk and — swamp clay (Eu-Molinion) (37.31) Fen, marsh and 7140 Transition mires and quaking — swamp bogs (54.5) Fen, marsh and 7210 Calcareous fens with Cladium — swamp mariscus and Carex davalliana (53.3) Fen, marsh and 7220 *Petrifying springs with tufa — swamp formation (Cratoneurion) (54.12) Fen, marsh and 7230 Alkaline fens (54.2) — swamp Fen, marsh and 7240 *Alpine pioneer formations of — swamp Caricion bicoloris-atrofuscae (54.3) Fen, marsh and 7250 Depressions on peat substrates — swamp (Rhynchosporion) (54.6) Bogs 7110 *Active raised bogs (51.1) — Bogs 7120 Degraded raised bogs still capable — of natural regeneration (51.2) Bogs 7130 Blanket bog (*active only) (52.1 and — 52.2) Standing open 3110 Oligotrophic waters containing — water and very few minerals of Atlantic canals sandy plains with amphibious vegetation: Lobelia, Littorella and Isoetes (22.11 Â 22.31) Standing open 3130 Oligotrophic waters in medio- — water and European and perialpine areas canals with amphibious vegetation: Littorella and Isoetes or annual vegetation on exposed banks (Nanocyperetalia) (22.12) + (22.31 & 22.31) BAP and Habitats Directive categories 487

BAP Broad Annex I Habitats Directivea Habitat code Annex I type Comment

Standing open 3140 Hard oligo-mesotrophic waters — water and with benthic vegetation of Chara canals formations (22.12 & 22.44) Standing open 3150 Natural eutrophic lakes with — water and Magnopotamion or canals Hydrocharition-type vegetation (22.13) Standing open 3160 Dystrophic lakes (22.14) — water and canals Standing open 3170 *Mediterranean temporary ponds — water and (22.34) canals Rivers and 3260 Floating vegetation of Ranunculus — streams of plain and sub-mountainous rivers (24.2) Montane 4060 Alpine and subalpine heaths Heaths that are mostly habitats (31.4) p.p. confined to the alpine zone, namely the NVC communities H13, H14, H15, H17, H19, H20 and H22, are included in the ‘Montane habitats’ broad habitat type Montane 4080 Sub-Arctic willow scrub (31.622) — habitats Montane 6150 Siliceous alpine and boreal — habitats grassland (36.32) Inland rock 6130 Calaminarian grasslands (34.2) — Inland rock 6430 Eutrophic tall herbs (37.7 and — 37.8) Inland rock 8110 Siliceous scree (61.1) — Inland rock 8120 Eutric scree (61.2) — Inland rock 8210 Chasmophytic vegetation on — rocky slopes: Calcareous sub-types (62.1 and 62.1A) Inland rock 8220 Chasmophytic vegetation on — rocky slopes: Silicicolous sub-types (62.2) Inland rock 8240 *Limestone pavements (62.4) — Built-up areas —— — and gardens 488 APPENDIX 2

BAP Broad Annex I Habitats Directivea Habitat code Annex I type Comment

Supralittoral 1230 Vegetated sea cliffs of the Atlantic — rock and Baltic coasts (18.21) Supralittoral 1210 Annual vegetation of drift lines — sediment (17.2) Supralittoral 1220 Perennial vegetation of stony — sediment banks (17.3) Supralittoral 2110 Embryonic shifting dunes (16.211) — sediment Supralittoral 2120 Shifting dunes along the shoreline — sediment with Ammophila arenaria (white dunes) (16.212) Supralittoral 2130 *Fixed dunes with herbaceous — sediment vegetation (grey dunes) (16.221 to 16.227) Supralittoral 2140 *Decalcified fixed dunes with — sediment Empetrum nigrum (16.23) Supralittoral 2150 *Eu-Atlantic decalcified fixed — sediment dunes (Calluno-Ulicetea) (16.24) Supralittoral 2160 Dunes with Salix arenaria (16.26) — sediment Supralittoral 2170 Humid dune slacks (16.31 to — sediment 16.35) Supralittoral 21A0 Machair (1.A) — sediment Supralittoral 2250 *Dune juniper thickets (Juniperus — sediment spp.) Littoral rock 8330 Submerged or slightly submerged — sea caves p.p. Littoral 1140 Mudflats and sandflats not cov- — sediment ered by sea water at low tide (14) Littoral 1160 Large shallow inlets and bays (12) — sediment Littoral 1310 Salicornia and other annuals colo- — sediment nising mud and sand (15.11) Littoral 1320 Spartina swards (Spartinion) — sediment (15.12) Littoral 1330 Atlantic salt meadows (Glauco- — sediment Puccinellietalia) (15.13) Littoral 1340 *Continental salt meadows — sediment (Puccinellietalia distantis) (15.14) Littoral 1410 Mediterranean salt meadows — sediment (Juncetalia maritimi) (15.15) BAP and Habitats Directive categories 489

BAP Broad Annex I Habitats Directivea Habitat code Annex I type Comment

Littoral 1420 Mediterranean and thermo- — sediment Atlantic halophilous scrubs (Arthocnememtalia fructicosae) (15.16) Inshore 1170 Reefs (11.24) — sublittoral rock Inshore 8330 Submerged or slightly submerged — sublittoral rock sea caves p.p. Inshore 1110 Sandbanks that are slightly — sublittoral covered by sea water all the time sediment (11.25) Offshore shelf —— — rock Offshore shelf —— — sediment Continental —— — shelf slope Oceanic seas — — — a Asterisks indicate Annex I Priority Habitat types. Appendix 3 Annotated list of key references for plant identification

LICHENS An updated checklist with new names and more species added to the 1992 flora. Broad, K. (1989) Lichens in Southern Woodlands. Forestry Seaward, M. R. D. (ed.) (1995 et seq.) Lichen Atlas of the British Commission Handbook No. 4. London: Her Majesty’s Isles. London: Lichen Society. Stationery Office. Contains A4 maps with ring binders, with comments on Contains photographs of 24 species that grow on trees distribution, ecology, status and identification. with a reproduction of a wall chart on lichens and pollution zones. Coppins, B. J. (2002) Checklist of Lichens of Great Britain and BRYOPHYTES Ireland. London: British Lichen Society. Dobson, F. S. (2000) Lichens. An Illustrated Guide to the British Blockeel, T. L. & Long, D. G. (1998) A Check-list and Census and Irish species, 4th edn. Richmond: The Richmond Catalogue of British and Irish Bryophytes. Cardiff: British Publishing Company. Bryological Society. General, with lots of photographs, descriptions, maps, keys. Daniels, R. E. & Eddy, A. (1990) Handbook of European Sphagna. Hodgetts, N. G. (1992) Cladonia: A Field Guide. Peterborough: London: Her Majesty’s Stationery Office. Joint Nature Conservation Committee. Each species fully described and illustrated, but difficult A small, cheap, simple, very useful field guide to this for beginners. genus. Hill, M. O. (1992) Sphagnum: A Field Guide, Peterborough: The Jahn, H. M. (1981) Collins Guide to Ferns Mosses and Lichens. Joint Nature Conservation Committee. London: Collins. A very useful field guide for non-specialists wanting to General; contains lots of photographs, but no keys; now identify Sphagnum in the field. out-dated but still generally good. Hill, M. O., Preston, C. D. & Smith, A. J. E. (eds) (1991, 1992, Orange, A. (1994) Lichens on Trees. A Guide to some of the 1994) Atlas of the Bryophytes of Britain and Ireland. Volumes 1, Commonest Species. British Plant Life No. 3. Cardiff: 2 & 3. Colchester: Harley Books. National Museum of Wales. Essential information on distribution and habitats of Contains 39 species, illustrated, although the British bryophytes. photographs are a bit small. Jahns, H. M. (1981) Collins Guide to Ferns, Mosses and Lichens. Purvis, O. W., Coppins, B. J., Hawksworth, D. L., James, P. J. & London: Collins. Moore, D. M. (1992) The Lichen Flora of Great Britain and Lots of photographs; general, but useful. Ireland. London: Natural History Museum Publications/ Paton, J. A. (1999) The Liverwort Flora of the British Isles. British Lichen Society. Colchester, Essex: Harley Books. The standard work, but highly technical. The checklist by Now the definitive liverwort flora, essential for full Coppins (2002) (see above) should be used for the identification. up-to-date names of lichens. Smith, A. J. E. (1978) The Moss Flora of Britain and Ireland. Purvis, O. W., Coppins, B. J. & James, P. W. (1993) Checklist of Cambridge: Cambridge University Press. lichens of Great Britain and Ireland. British Lichen Society Full keys, rather limited illustrations. The definitive work Bulletin, 72 (Supplement). on mosses to date, essential for full identification,

# RPS Group plc and Scottish Natural Heritage 2005. Key references for plant identification 491

although some of the species and/genus names are now out of date and there have been species splits. The various VASCULAR PLANTS individual keys for groups and the checklist by Blockeel & Blamey, M., Fitter, R. & Fitter, A. (2003) Wild Flowers of Britain Long (1998) (see above) need to be consulted. The key to and Ireland. London: A. & C. Black. genera was updated by Smith (1991) in Bulletin of the British Clapham, A. R., Tutin, T. G. & Moore, D. M. (1987) Flora Bryological Society, 57, 41–62. An updated edition of of the British Isles, 3rd edn, reprinted with corrections Smith’s Flora is due to be published in 2004. 1989. Cambridge: Cambridge University Press. Smith, A. J. E. (1990) The Liverworts of Britain and Ireland. The 3rd edition of the once classic flora in standard use Cambridge: Cambridge University Press. in Britain from 1951 to 1991, now largely superseded Full keys, many illustrations, now replaced by Paton by Stace (1997) (see below). Still very useful as it (1999) (see above). contains more comprehensive descriptions of plants Watson, E. V. (1981) British Mosses and Liverworts, 3rd edn. and their distributions. Cambridge: Cambridge University Press. Dudman, A. A. & Richards, A. J. (1997) Dandelions of Great Covers most species with keys, illustrations, and helpful Britain and Ireland, BSBI Handbook No. 9. London: ecological comments. Very useful and quicker to use, Botanical Society of the British Isles. especially to genera, than the definitive works of Smith Graham, G. G. & Primavesi, A. L. (1993) Roses of Great Britain and Paton (see above). Some identification characters are and Ireland, BSBI Handbook No. 7. London: Botanical erroneous, however (e.g. Aloina), the taxonomy is very out Society of the British Isles. of date, and the species covered in detail are not always Haslam, S., Sinker, C. & Wolseley, P. (1987) British the commonest members of their genus (for example, Water Plants (revised). Shrewsbury: Field Studies Plagiothecium denticulatum is much less common than P. Council. nemorale or P. succulentum). Hubbard, C. E. (1984) Grasses, 3rd edn (revised by J. C. E. Hubbard). London: Penguin Books. Jermy, A. C., Chater, A. O. & David, R. W. (1982) Sedges of the CHAROPHYTES British Isles, 2nd edn BSBI Handbook No. 1. London: Moore, J. A. (1986) Charophytes of Great Britain and Ireland. Botanical Society of the British Isles. London: Botanical Society of the British Isles. Lousley, J. E. & Kent, D. H. (1981) Docks and Knotweeds of the Covers identification (keys, descriptions, drawings) and British Isles, BSBI Handbook No. 3. London: Botanical distribution of all British and Irish species. Society of the British Isles. Stewart, N. F. & Church, J. M. (1992) Red Data Books of Britain Meikle, R. D. (1984) Willows and Poplars of Great Britain and and Ireland: Stoneworts. Peterborough: Joint Nature Ireland, BSBI Handbook No. 4. London: Botanical Society Conservation Committee. of the British Isles. Contains a key to identification. Preston, C. D. (1995) Pondweeds of Great Britain and Ireland, BSBI Handbook No. 8. London: Botanical Society of the British Isles. FERNS Rich, T. C. G. (1991) Crucifers of Great Britain and Ireland, BSBI Handbook No. 6. London: Botanical Society of the British Hutchinson, G. & Thomas, B. A. (1997) Welsh Ferns, 7th edn. Isles. Cardiff: The National Museum of Wales. Rich, T. C. G. & Jermy, A. C. (eds) (1998) Plant Crib 1998. Jermy, C. & Camus, J. (1991) The Illustrated Field Guide to Ferns London: Botanical Society of the British Isles. and Allied Plants of the British Isles. London: Her Majesty’s Hints on identification of numerous difficult genera. Stationery Office and Botanical Society of the British Isles. Rose, F. (1981) The Wild Flower Key. London: Frederick Page, C. N. (1997) The Ferns of Britain and Ireland, 2nd edn. Warne. Cambridge: Cambridge University Press. Contains the only vegetative keys available to various One of the best of several standard texts on fern habitats (these are also sold separately), and numerous identification, with descriptions, keys, ecological notes field jizz characteristics. and small maps. 492 APPENDIX 3

Rose, F. (1989) Colour Identification Guide to the Grasses, definitive flora with keys, drawings and diagnostic Sedges, Rushes and Ferns of the British Isles and descriptions. North-western Europe. Middlesex: Viking. Stace, C. A. (1999) Field Flora of the British Isles. Cambridge: Keys and colour illustrations. Cambridge University Press. A condensed version Sell, P. D. & Murrell, G. (1996) Flora of Great Britain of Stace (1997). and Ireland,Volume5:Butomacaeae – Orchidaceae. Tutin, T. G. (1980) Umbellifers of the British Isles, BSBI Cambridge: Cambridge University Press. Handbook No. 2. London: Botanical Society of the Stace, C. A. (1997) New Flora of the British Isles, 2nd edn. British Isles. Cambridge: Cambridge University Press. The current Appendix 4 Determining appropriate quadrat size for vegetation sampling

The size of a quadrat affects the measured values of quadrat size should therefore ideally be such that frequency, density, and cover, etc. (see Figure A4.1 mean frequencies of all species fall within this below). It is therefore important to decide in range. If a quadrat is one or two times larger than advance which values are to be measured. the mean area per individual of the most common Experience has shown that different vegetation species, randomly distributed species will have types and different measurement types require dif- mean frequencies of 63% and 86% for these quadrat ferent quadrat sizes. In Part II, quadrat methods for sizes (Bonham, 1989). However, selection of a sin- habitat monitoring are described in Sections 6.4.2 gle quadrat size is obviously not appropriate for (frame quadrats for cover and density estimates); measuring all the species in a community. This 6.4.3 (random mini-quadrats for frequency esti- problem can be overcome by using a series of quad- mates); 6.4.4 (FIBS analysis); and 6.4.5 (point quadrat sizes at each sample point in a ‘nested’ design rats). Quadrat size is also considered in the section (see Part II, Section 6.4.4) that gives frequencies on NVC mapping (Section 6.1.6). In Part III, the between 5% and 95% for the maximum number of chapters on species groups and Chapter 10 also species. contain discussions of quadrat methods, where There will be no need to use nested quadrats if appropriate to the species group concerned. the type of community to be sampled is known in This appendix deals with the selection of the advance; there is little point in using quadrats of appropriate quadrat size. Methods for calculating 1m2 if you are measuring the density of pine trees the number of quadrats required are given in Part I, in a forest. Section 2.3.4. Frequency estimates are given the The type of measurement being made will also most attention, because quadrat size affects fre- affect the optimal quadrat size; for example, cover quency measures more than others (see Figure estimates are most accurate in small quadrats. A4.1). However, the lists of optimum quadrat size However, as a minor consideration with smaller for different vegetation types can generally be quadrats, there is a proportionally increased error applied to all quadrat sampling methods (with the associated with the boundary of the quadrat obvious exception of point quadrats). because the edge : area ratio is higher (boundary Techniques for determining optimum quadrat errors are observer errors, such as including an size for frequency measures are subjective, and a individual near to the boundary when in fact it is quadrat of any size will sample some species more outside the quadrat, or not including individuals adequately than others. The quadrat size chosen that are inside the quadrat). will therefore depend upon the type of vegetation Vegetation with smaller plants, greater density being sampled. The use of random mini-quadrats or greater species diversity require smaller quad- for estimating frequency is described in Part II, rats in order to reduce the complexity of the sam- Section 6.4.3. pling unit to a manageable level. However, if Frequencies greater than 95% and less than 5% specific species surveys are required, larger quad- can result in heavily skewed distributions. The rats are needed for species that are small but rare.

# RPS Group plc and Scottish Natural Heritage 2005. 494 APPENDIX 4

such as that given below. Nevertheless, you should bear in mind the considerations outlined above, A particularly for frequency data, rather than employing a certain quadrat size without thinking about it. One advantage of using nested quadrats of different sizes (Part II, Section 6.4.4) is that the most B appropriate size for analysis of each species can be chosen once all the data have been collected. The sizes most often used for different vegetation types are:

2 * 0.01–0.25 m in bryophyte, lichen and algal communities 2 * 0.25–16.0 m in grassland, tall herb, short scrub or Figure A4.1. The effects of quadrat size on the aquatic macrophyte communities measurements of biomass, cover, density and 2 * 25–100 m for tall shrub communities frequency. Quadrat A is four times the size of quadrat 2 * 400–2500 m for trees in woods and forests B. A single quadrat of size A will be more likely to ‘hit’ an individual of a species than a single quadrat of size However, other optimal quadrat sizes have been B. If several quadrats are laid out (for simplicity the suggested. The following optimal quadrat sizes whole area is covered by quadrats in this example), the have been suggested for frequency estimates: estimates of biomass, cover and density will be the 2 * 0.01–0.1 m for the moss layer same using quadrats A or B. However, there will be 2 * 1–2 m for the herb layer more between-quadrat variation for the B quadrats, 2 * 4m for tall herbs and low shrubs and the different quadrat sizes give different estimates 2 * 10 m for tall shrubs and low trees of frequency. This occurs for any distribution pattern 2 * 100 m for trees of a species or habitat type. In this example with a clumped distribution, B quadrats give a frequency NVC mapping (Part II, Section 6.1.6) uses stan- estimate of 13/36 = 0.36 and A quadrats give an dardised quadrat sizes for different vegetation estimate of 7/9 = 0.78. For frequency measures it is types. These are summarised in Box 6.12. useful to choose a size that avoids extreme values. There is also a consideration of cost and time to Source: Greenwood (1996). be made when deciding what size of quadrat to use; larger quadrats will obviously be more time- There is much more that could be said about consuming (and therefore more costly) to record choosing optimal quadrat size; see Bonham (1989) than will smaller ones. Finally, if you are repeating for a more rigorous analysis. However, there is no a previous monitoring survey, the same size of simple rule for calculating optimal size. It is there- quadrat as was used in the previous survey should fore probably more straightforward to use a rule of be employed to enable valid comparisons to be thumb based upon the community being sampled, made between the different data sets. Appendix 5 The relocation of permanent plots

Various techniques (e.g. quadrats and transects) PAINT have been used to mark permanent plots; these are described briefly below. A general point to con- Paint has been used to mark plots, especially where sider is that the more techniques used, the quicker rocks, walls or posts are available nearby. It can it will normally be to find plots again. often be used discreetly, but tends to fade and disappear with time. Timber dye is better for marking wood than is ordinary paint (N. A. Robinson, perso- MAPPING nal communication). Measurements to nearby features have been widely used to map locations of plots and are relatively BURIED METAL MARKERS foolproof, provided that mapping is accurate (use a backsighting compass for bearings and measure Buried metal markers (aluminium plates, wire mesh, distances correctly) and that the features chosen ironbars,etc.),whichcanbere-foundbyusing are fixed and permanent. This is particularly metal detectors, can be used for marking plots. important for long-term monitoring studies; fea- Transponders can also be used, which are re-found tures such as fence posts may be damaged or lost by using a hand-held scanning device. Transponders over time. However, the method is often difficult to give off a unique signal, so there is no confusion apply in large homogeneous habitats, such as grass- about the identity of relocated markers. lands, where obvious permanent features are lack- As these are hidden they are not unsightly and do ing. It is also time-consuming when a large number not attract the unwanted attention of people or live- of plots need to be relocated. stock. However, burying the markers causes disturbance to the habitat, and the metal may corrode or cause localised toxicity; in addition, the widespread MARKER POSTS use of metal detectors by treasure hunters may Wooden or metal posts are widely used and can be result in their being dug up. It is difficult to bury quick to re-find in relatively small sites. However, markers on very shallow soils, and frost heaving of small markers can be hidden by vegetation. Large soil in the uplands may result in movement or expo- markers can cause significant damage to habitats, sure of the markers. Unless accompanied by mea- tend to be unsightly and attract the attention of surements or photographs, the precise positions of people. Animals too may scratch against large mar- markers can be very time-consuming to find. kers, thereby causing disproportionate disturbance to vegetation, resulting in bias in the sampling. PHOTOGRAPHS Unless markers are strong and well secured they may be broken by livestock or removed by vandals, Photographs can speed positioning of plots, but in etc. Posts may also be lost over time through rot- most cases are unlikely to allow precise relocation ting or corrosion and even frost heave. of individual quadrats.

# RPS Group plc and Scottish Natural Heritage 2005. 496 APPENDIX 5

they can be very cost-effective when the potential TOTAL STATIONS reduction in survey time is taken into account. Total Stations are essentially surveying instru- They may also be hired for approximately £100 ments that combine theodolites and laser range per week. finders to allow the highly accurate measurements Their disadvantages are that they are not cost- of bearings, distances and ground level. These effective or time-efficient when only a small num- allow the fast and accurate relocation of plots as ber of plots need to be relocated. Two operators are well as providing additional data if required (such also required. It is also problematical to use them as topography maps). Current models are now on very large sites because they are cumbersome to waterproof and relatively portable (pack size move around and require about 25 minutes to set approximately the size of a suitcase, mass c. 11 kg) up at each fixed point. They cannot be used in and are now much more suited to ecological enclosed habitats such as woodland or scrubland fieldwork. Cranfield University, for example, has or on very uneven sites, unless the Station can be very successfully used them for relocating perma- set up on a high point. nent transects as part of long-term studies of plant water requirements (D. Gowing, personal GLOBAL POSITIONING SYSTEMS (GPS) communication). Plots are located by placing the Total Station Recent technological advances, together with the over a fixed permanent base marker (e.g. a bolt removal of signal degradation through ‘selective drilled into a fixed object) and directing an assis- availability’, have led to considerable increases in tant with a laser-reflecting prism on a staff to a the accuracy of handheld GPS. These are now cap- location pre-recorded according to its bearing and able of locating and relocating positions to an distance. A radio is required to communicate accuracy of 10 to 20 m or better, depending on between the station operator and the assistant atmospheric conditions. Hand-held GPS units can holding the staff. Current Total Stations operate currently be purchased for about £200–£300. up to a distance of c. 1 km and have an accuracy of If sub-metre accuracy is required, differential 2 in 1 million, and thus can relocate plots to within GPS (DGPS) can be used. DGPS units receive GPS a couple of millimetres if required. In practice, this signals and combine them with error correction level of accuracy is tricky and time-consuming to signals from fixed stations, whose precise locations obtain. However, an accuracy to 1–2 cm can easily are known. DGPS can be more time-consuming to be achieved. Quadrats can be relocated by record- use and the equipment is much more expensive ing two diagonal points of each plot, whereas for and bulky than hand-held units. Both of these sys- transects only the start and end points need to be tems are limited by a requirement to have a clear recorded. view of the sky, and do not function well in dense The main advantage of Total Stations is that they tree cover, for example. allow very rapid relocation of plots. They are also Although by itself GPS is still insufficient for accurate enough to negate the need for marking exact relocation of plots for most monitoring pur- the plot at all, thereby avoiding the damage caused poses, it can be very useful when combined with by animals and other disadvantages of using posts, other techniques, particularly on very large sites. etc. They can also help enormously with accurate For example, GPS can be used on moorland sites to mapping of vegetation, topography and other phy- direct the surveyor to a search zone within which a sical features if required. Although new models small unobtrusive marker can be used to locate the cost about £4000 (£2000–£3000 for older versions) exact plot. Appendix 6 Equipment required for undertaking different types of survey

# RPS Group plc and Scottish Natural Heritage 2005. 498 APPENDIX 6 uvyn fungi Surveying tc mapping Stock plots Permanent plots Temporary sampling Plotless eilphotography Aerial photography Fixed-point surveying habitat I Phase mapping NVC uvyn fungi Surveying fungi Surveying using by fungi Surveying edwo survey wood Dead rpe sampling Grapnel yuigquadrats using by transects using by photography fixed-point n monitoring and fautcvegetation aquatic of

Good-quality overlapping aerial ** photographs Stereoscope/stereo-analyst * software Photogrammetric plotting machine (used to create maps – * optional) Sketchmaster for transfer of interpretation to base map * (optional) Digitising hardware and software **** (optional) Light table (optional) * 35 mm single-lens reflex camera * * 28–35 mm lens for normal shots * * and 50 mm for detail Slide films or digital memory * * * * Sturdy tripod with easily adjust- able legs and central column and a ball and socket head. If the fixed-angle method is to be used * * (see text) then an additional Linhof Propan pan and tilt head (Model II) is recommended Standard 2 m ranging pole (and ranging-pole support for rocky * sites) if the centre pole system is to be used Cable release * * Spare batteries for camera * * Large-scale site map with pencils * and ball-point pens Map of the site at a useable scale, * e.g. 1 : 5000 OS map or sketch map to mark * location of the photograph Equipment required for undertaking different types of survey 499 aclrpatdemography plant Vascular uvyn aclrplants vascular Surveying uvyn bryophytes Surveying udasadtransects and quadrats sn avlegcounts: larval/egg using uvyn utrle yusing by butterflies Surveying by butterflies Surveying uvyn rgnle and dragonflies Surveying and dragonflies Surveying uvyn aclrplants vascular Surveying uvyn rohtsby bryophytes Surveying bryophytes Surveying bryophytes Surveying using bryophytes Surveying vegetation aquatic Surveying uvyn lichens Surveying using lichens Surveying ie avlegcounts larval/egg timed aslle yexuviae by damselflies transect/ by damselflies yfxdpitphotography fixed-point by iulestimation visual transects using quadrats using by photography fixed-point transects and quadrats by yuigquadrats using by photography fixed-point ie count timed

****

** *

** **

***

** 500 APPENDIX 6 uvyn fungi Surveying tc mapping Stock plots Permanent plots Temporary sampling Plotless eilphotography Aerial photography Fixed-point surveying habitat I Phase mapping NVC uvyn fungi Surveying fungi Surveying using by fungi Surveying edwo survey wood Dead rpe sampling Grapnel yuigquadrats using by transects using by photography fixed-point n monitoring and fautcvegetation aquatic of

Safety equipment as necessary * * * * * * * * * * * * * Copies of 1 : 10 000 or 1 : 25 000 ** field maps 1 : 50 000 Ordnance Survey maps * Binoculars/telescope * Pen for annotating prints Clipboard coloured pencils, lead pencils, rubber, pens, notebook, waterproof paper, plastic bags or *** * **** * * * * * weather writer (for protection of notebook in wet weather) Botanical field guides and Â 10 ** * * * * hand lens GPS * * * Berol Verithin coloured pencils, Rotring drawing pens (0.35 mm, * 0.5 mm) T-squares, set-squares, rulers * Calculators * Romer dot grids (for measuring areas and determining grid ** references) Line-hatching apparatus (optional) * * Planimeter (optional) * * Handbook for Phase I Survey Field * Manual Quadrats, which for most circumstances can simply be made out of string or washing line (which does not tangle as easily as string) with ***** a tent peg at each corner, and/or a 50 m tape measure with a tent peg at one end for convenience Summaries of NVC communities or copies of tables alone, or * appropriate NVC volumes if summaries are not available Equipment required for undertaking different types of survey 501 aclrpatdemography plant Vascular uvyn aclrplants vascular Surveying uvyn bryophytes Surveying udasadtransects and quadrats sn avlegcounts: larval/egg using uvyn utrle yusing by butterflies Surveying by butterflies Surveying uvyn rgnle and dragonflies Surveying and dragonflies Surveying uvyn aclrplants vascular Surveying uvyn rohtsby bryophytes Surveying bryophytes Surveying bryophytes Surveying using bryophytes Surveying vegetation aquatic Surveying uvyn lichens Surveying using lichens Surveying ie avlegcounts larval/egg timed aslle yexuviae by damselflies transect/ by damselflies yfxdpitphotography fixed-point by iulestimation visual transects using quadrats using by photography fixed-point transects and quadrats by yuigquadrats using by photography fixed-point ie count timed

************* * *

**** *

************* * *

* *** * * * ****

***** 502 APPENDIX 6 uvyn fungi Surveying tc mapping Stock plots Permanent plots Temporary sampling Plotless eilphotography Aerial photography Fixed-point surveying habitat I Phase mapping NVC uvyn fungi Surveying fungi Surveying using by fungi Surveying edwo survey wood Dead rpe sampling Grapnel yuigquadrats using by transects using by photography fixed-point n monitoring and fautcvegetation aquatic of

Coloured pencils/fine liner pens * for mapping habitat extent Snorkelling/diving equipment (if required) Clipboard/weather writer, NVC recording sheets (or paper), * waterproof paper Hand lens, plant identification guides and plastic bags with waterproof labels for samples; a plant press may be useful if away ***** for long periods of survey for higher plants, and bryophyte packets or nylon mesh bags for samples Grapnel (7 cm) and/or * underwater viewer Graduated cord * Standard recording equipment * or data logger Boat (for most water bodies) * Vertical aerial photographs * Compass * * * * * * * * * Sighting compass Ranging poles * * * * * * Increment borer (optional) * Tape measure(s) * * * Cartographical equipment * Equipment for analysis of maps * once created 30–50 m tapes, preferably bright yellow or white, to lay out plots, *** and provide axes for co-ordinates Galvanised angle-irons or posts, up to 1.3 m long, to be perman- * ent markers Equipment required for undertaking different types of survey 503 aclrpatdemography plant Vascular uvyn aclrplants vascular Surveying uvyn bryophytes Surveying udasadtransects and quadrats sn avlegcounts: larval/egg using uvyn utrle yusing by butterflies Surveying by butterflies Surveying uvyn rgnle and dragonflies Surveying and dragonflies Surveying uvyn aclrplants vascular Surveying uvyn rohtsby bryophytes Surveying bryophytes Surveying bryophytes Surveying using bryophytes Surveying vegetation aquatic Surveying uvyn lichens Surveying using lichens Surveying ie avlegcounts larval/egg timed aslle yexuviae by damselflies transect/ by damselflies yfxdpitphotography fixed-point by iulestimation visual transects using quadrats using by photography fixed-point transects and quadrats by yuigquadrats using by photography fixed-point ie count timed

* *** * * * ****

* * **

* * ***** * *

* 504 APPENDIX 6 uvyn fungi Surveying tc mapping Stock plots Permanent plots Temporary sampling Plotless eilphotography Aerial photography Fixed-point surveying habitat I Phase mapping NVC uvyn fungi Surveying fungi Surveying using by fungi Surveying edwo survey wood Dead rpe sampling Grapnel yuigquadrats using by transects using by photography fixed-point n monitoring and fautcvegetation aquatic of

Girth tapes, short and long * * * * Paper, preferably squared (or datalogger for recording directly *** into a computer) Hypsometer or Abney level *** * (optional) Relascope (optional) * Quadrats or transect markers * painted a bright light colour Pegs or hooks for attaching string to grid markers String * * * * * Stopwatch (if searches are timed) * Collecting materials: small containers, waxed paper, tubes, jars, ** * plastic bags, etc. as appropriate Hand lens ** * Transect, e.g. poles, measuring * tape Permanent markers for quadrat ** corners (if required) Tape or rope to split larger ***** quadrats Knife (with fixed blade) and bags ***** for collecting Transponders and metal * detector KOH and bleach solution (used in identification) Hooked stick for collecting plants Plastic bag to keep the dry-wipe board dry Marker pen for the dry-wipe board Equipment required for undertaking different types of survey 505 aclrpatdemography plant Vascular uvyn aclrplants vascular Surveying uvyn bryophytes Surveying udasadtransects and quadrats sn avlegcounts: larval/egg using uvyn utrle yusing by butterflies Surveying by butterflies Surveying uvyn rgnle and dragonflies Surveying and dragonflies Surveying uvyn aclrplants vascular Surveying uvyn rohtsby bryophytes Surveying bryophytes Surveying bryophytes Surveying using bryophytes Surveying vegetation aquatic Surveying uvyn lichens Surveying using lichens Surveying ie avlegcounts larval/egg timed aslle yexuviae by damselflies transect/ by damselflies yfxdpitphotography fixed-point by iulestimation visual transects using quadrats using by photography fixed-point transects and quadrats by yuigquadrats using by photography fixed-point ie count timed

* ** * **

****

** * *

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* *** **

* ****

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* *** * * * ****

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* 506 APPENDIX 6 uvyn fungi Surveying tc mapping Stock plots Permanent plots Temporary sampling Plotless eilphotography Aerial photography Fixed-point surveying habitat I Phase mapping NVC uvyn fungi Surveying fungi Surveying using by fungi Surveying edwo survey wood Dead rpe sampling Grapnel yuigquadrats using by transects using by photography fixed-point n monitoring and fautcvegetation aquatic of

Dry-wipe board (or clipboard in a plastic bag) annotated with sample point location, etc. (included in the photograph to assist identification during later analysis) Pond net Butterfly net Sticks to place in water for emergent Odonata (if required) Equipment required for undertaking different types of survey 507 aclrpatdemography plant Vascular uvyn aclrplants vascular Surveying uvyn bryophytes Surveying udasadtransects and quadrats sn avlegcounts: larval/egg using uvyn utrle yusing by butterflies Surveying by butterflies Surveying uvyn rgnle and dragonflies Surveying and dragonflies Surveying uvyn aclrplants vascular Surveying uvyn rohtsby bryophytes Surveying bryophytes Surveying bryophytes Surveying using bryophytes Surveying vegetation aquatic Surveying uvyn lichens Surveying using lichens Surveying ie avlegcounts larval/egg timed aslle yexuviae by damselflies transect/ by damselflies yfxdpitphotography fixed-point by iulestimation visual transects using quadrats using by photography fixed-point transects and quadrats by yuigquadrats using by photography fixed-point ie count timed

* *

* Surveying fish by direct * * counting Surveying aquatic invertebrates by cylinder sampling Surveying aquatic invertebrates by kick sampling Surveying aquatic invertebrates by sweep netting Surveying aquatic

invertebrates by vegetation ** Surveying invertebrates by using artificial refugia Surveying invertebrates by

using window traps * Surveying invertebrates by

using suction sampling * Surveying invertebrates by using pitfall traps Surveying invertebrates by using quadrats Surveying invertebrates by

using timed searches * Surveying adult and larval invertebrates Surveying macromoths by using pheromone traps Surveying macromoths by using light traps Surveying adult butterflies

by using transects ************** * ** ** ** ************** * 508 APPENDIX 6 Safety equipment as necessary Copies of 1:10,000 or 1:25,000 field maps 1:50,000 Ordnance Survey maps Binoculars/telescope * Quadrats or transect markers painted a bright light colour Pegs or hooks for attaching string to grid markers String Snorkelling/diving equipment (if required) Boat (for most water bodies) Ranging RolesTape measure(s)Fieldnote recording equipment * Stopwatch (if searches are timed) Collecting materials – small containers, waxed paper, tubes, *jars, plastic bags, etc. as appropriate Hand lensQuadrats or transectsPermanent markers for * quadrat corners Tape/rope to split larger quadrats * Pond net Butterfly netTorchPheromone trap * * * * * * * * Surveying birds by using line transects * Surveying birds by using territory mapping Surveying reptiles by using mark-recapture Surveying reptiles by

using trapping techniques *** Surveying reptiles by using transects

Surveying reptiles by using artificial refugia Surveying amphibians by mark-recapture Surveying amphibians by

egg searching ** Surveying amphibians by ** terrestrial transect searches ***** Surveying amphibians by pitfall trapping Equipment required for undertaking different types of survey 509 Surveying amphibians by sweep netting Surveying amphibians by bottle traps Surveying amphibians by torch counts ** * Surveying fish by electrofishing Surveying fish by push, throw and lift netting Surveying fish by trawl netting Surveying fish by seine

netting **************** * **************** * Surveying fish by trapping * * ** * * * Surveying fish by direct counting Surveying aquatic invertebrates by cylinder sampling Surveying aquatic invertebrates by kick sampling Surveying aquatic invertebrates by sweep netting Surveying aquatic invertebrates by vegetation Surveying invertebrates by using artificial refugia Surveying invertebrates by

using window traps * * Surveying invertebrates by * * using suction sampling * Surveying invertebrates by

using pitfall traps * * * ****** * * Surveying invertebrates by

using quadrats * * Surveying invertebrates by using timed searches Surveying adult and

larval invertebrates *** Surveying macromoths by using pheromone traps Surveying macromoths by using light traps Surveying adult butterflies by using transects 2 510 APPENDIX 6 PheromonesPooter/aspiratorSampling equipment as required (e.g. secat- eurs, knife, trowel). * Sample bags for vegetation or soil * * * * Clippers and bags for plant material Sieves and photographic trays for sorting Sieve and filtersPitfall traps (e.g. large yogurt pots) and lids Pieces of wire mesh (for covering trap) and staples Trowel, soil corer on first visit Ethylene glycol or other preservative Watertight collecting jars Funnel and container for removing trap fluid Suction sampler, nets and fuel * * Killing agent (ethyl acetate) and cotton wool Steel ring – 0.25 m Wooden stake, mallet, platform, brackets, screws Perspex sheetingTrays of various colours, water, detergent * Surveying birds by using line transects Surveying birds by using territory mapping Surveying reptiles by using mark-recapture Surveying reptiles by using trapping techniques Surveying reptiles by using transects

Surveying reptiles by using artificial refugia Surveying amphibians by mark-recapture Surveying amphibians by egg searching Surveying amphibians by terrestrial transect searches Surveying amphibians

by pitfall trapping **

Equipment required for undertaking different types of survey 511 Surveying amphibians by sweep netting Surveying amphibians by bottle traps Surveying amphibians by torch counts Surveying fish by electrofishing Surveying fish by push, throw and lift netting Surveying fish by trawl netting Surveying fish by seine netting Surveying fish by trapping Surveying fish by direct * * * counting Surveying aquatic invertebrates

by cylinder sampling * Surveying aquatic invertebrates

by kick sampling * Surveying aquatic invertebrates by sweep netting Surveying aquatic

invertebrates by vegetation **** *** *** **** Surveying invertebrates by using artificial refugia * Surveying invertebrates by

using window traps * * Surveying invertebrates by using suction sampling Surveying invertebrates by using pitfall traps Surveying invertebrates by using quadrats Surveying invertebrates by using timed searches Surveying adult and larval invertebrates Surveying macromoths by using pheromone traps Surveying macromoths by using light traps Surveying adult butterflies by using transects 512 APPENDIX 6 Interlocking Perspex sheets Ethanol/glycerol solution Collecting jarsCardboard/slate/ceramic/wooden tiles Collecting buckets or bottles and/or net White plastic tray for sorting * captures Marker, waterproof labels *Plastic specimen tubes *Kick net or Surber sampler *Cylinder sampler Polarised glasses *Fish counters and data loggers *Video camera (optional) *Traps (baskets, cages, pots, * fykes or intercepts) Floats, * rope (for marking traps) Seine * net and haul ropes *Dip net Measuring board, *scale envelopes, etc. Trawl net * Lines Nets Generator Electrofishing equipment Surveying birds by using line transects Surveying birds by using territory mapping Surveying reptiles by

using mark-recapture * Surveying reptiles by using trapping techniques Surveying reptiles by using transects

Surveying reptiles by using artificial refugia Surveying amphibians by mark-recapture Surveying amphibians by egg searching Surveying amphibians by terrestrial transect searches Surveying amphibians by pitfall trapping

Equipment required for undertaking different types of survey 513 Surveying amphibians by sweep netting Surveying amphibians by bottle traps Surveying amphibians by torch counts Surveying fish by

electrofishing * * Surveying fish by push,

throw and lift netting *** Surveying fish by trawl

netting * * Surveying fish by seine

netting * * * Surveying fish by trapping * * Surveying fish by direct counting Surveying aquatic invertebrates by cylinder sampling Surveying aquatic invertebrates by kick sampling Surveying aquatic invertebrates by sweep netting Surveying aquatic invertebrates by vegetation Surveying invertebrates by using artificial refugia Surveying invertebrates by using window traps Surveying invertebrates by using suction sampling Surveying invertebrates by using pitfall traps Surveying invertebrates by using quadrats Surveying invertebrates by using timed searches Surveying adult and larval invertebrates Surveying macromoths by using pheromone traps Surveying macromoths by using light traps Surveying adult butterflies by using transects 65 cm galvanised 514 APPENDIX 6 Â Bottle traps Tank to keep trapped animals (if they are to be photographed before release) Sweep net Holding tank 10 litre buckets with lids Black plastic polythene sheeting (1000 gauge), 750 mm wide Staple gun, staples Spades, trowels, mallet Panjet ink gun (if required) PIT tags and scanner (if required) Camera and photo- booth (clear perspex box and sponge) for photography (if required) 76 corrugated steel sheets Gloves and gaiters (where adders are likely to occur). Laser range-finder for medium to long distance measurements where exact distance estimates are required Killing jarMoth trap * * Surveying birds by using line transects * Surveying birds by using territory mapping Surveying reptiles by using mark-recapture Surveying reptiles by using trapping techniques Surveying reptiles by using transects

Surveying reptiles by using artificial refugia * **** Surveying amphibians by

mark-recapture * ** ** Surveying amphibians by egg searching Surveying amphibians by terrestrial transect searches Surveying amphibians

by pitfall trapping ** ** ** ** Surveying amphibians Equipment required for undertaking different types of survey 515

by sweep netting * ** * ** Surveying amphibians

by bottle traps ** * Surveying amphibians by torch counts Surveying fish by electrofishing Surveying fish by push, throw and lift netting Surveying fish by trawl netting Surveying fish by seine netting Surveying fish by trapping Surveying Water Voles * * Surveying mammals by

using mark--recapture * * Surveying mammals by trapping Surveying mammals by using transects Surveying mammals by using hair tubes or catches Surveying mammals by using tracks Surveying mammals by using feeding signs Surveying mammals by using faecal pellet counts Surveying mammals

by using counts **** * **** ** of breeding sites Surveying bats by using field signs Surveying bats by using transects Surveying bats by using bat boxes Surveying bats by

hibernation counts **** Surveying bats by swarming counts Surveying bats ****** * * ** ***** * *** * * ** *** ****** * * ** ***** by exit counts * * 516 APPENDIX 6 Map of the site at a useable scale, e.g. 1: 5000 Safety equipment as necessary Copies of 1:10 000 or 1:25 000 field maps 1:50 000 Ordnance Survey maps Binoculars/ telescope GPSRanging poles Tape measure(s) Fieldnote recording equipment * Quadrats or transects Wellington boots/waders Torch * * Collecting jarsVideo camera (optional) Moth trap Hand-held counter * Large-scale site map with pencils and ball- point pens Surveying Water Voles Surveying mammals by using mark--recapture Surveying mammals by trapping Surveying mammals by using transects Surveying mammals by using hair tubes * * or catches Surveying mammals

by using tracks * Surveying mammals by using feeding signs Surveying mammals by using faecal pellet counts Surveying mammals by using counts of breeding sites Surveying bats by

using field signs * Equipment required for undertaking different types of survey 517 Surveying bats by using transects Surveying bats by using bat boxes Surveying bats by

hibernation counts * * Surveying bats by swarming counts Surveying bats

by exit counts * * Image intensifier Automatic counting device Bat detectorThermometerMonocular can *be useful for sites with high *ceilings *Humidity * gauge LadderCloth bag * Bat boxesTape recorderAngled mirrorsEndoscope (if available) * * * * * * Fine sand in shallow trays with a simple canopy, or inkpads and blotter, depending on the chosen method Lengths of plastic drainpipe tubing, size and number depending on methodology Lengths of mal- leable wire to attach tubes to trees, if placed above ground Surveying Water Voles Surveying mammals by

using mark--recapture * * Surveying mammals

by trapping ** ** ** * * Surveying mammals

by using transects * * Surveying mammals by using hair tubes * * * * * or catches Surveying mammals by using tracks Surveying mammals by using feeding signs Surveying mammals by using faecal pellet counts Surveying mammals by using counts of breeding sites Surveying bats by using field signs Surveying bats by using transects Surveying bats by using bat boxes Surveying bats by hibernation counts Surveying bats by swarming counts Surveying bats by exit counts 518 APPENDIX 6 Shorter lengths of fine wire Bait: peanuts, sunflowers and other seeds Pliers Sticky tape Reflective tape 100 W spotlight (or more powerful if car mounted) 10 to 20 appropriate traps Suitable bait for your target species Absorbent bedding, such as hay Bags in which to empty traps Canes to mark trap locations Markers to indicate the location of each trap Ear tags, hair clippers, or PIT tags and scanner depending on species and methodology Lengths of multi-stranded strong wire Recommended sources of further information

HABITAT REQUIREMENTS Whitton et al. (1991) Institute of Terrestrial Ecology (1986) (CHAPTER 5) Wright et al. (1981, 1994) Jones & Reynolds (1996) Wright, J. F. et al. (1997) Kirby, K. J. (1992, 1988) See the following references: Koop (1989) Langdale-Brown et al. (1980) Andrews (1995) SURVEY METHODS Lillesand & Kiefer (1994) Bell (1996) (CHAPTER 6) Lindsay & Ross (1994) Boon & Howell (1997) See the following references: Lunetta & Elvidge (1999) Boon & Raven (1998) Mackey et al. (1998) Boon et al. (1992) Allen (1989) MLURI (1993) Boon et al. (1996a) Archibald (1981) Moodie (1991) Brookes (1991) Barr et al. (1993) Mountford & Peterken (1998) Calow & Petts (1992, 1994) Bignal (1978) NCC (1987) Environment Agency (2003) Bonham (1989) NCC (1990a,b, 1991) Farmer (1990) Bragg et al. (1994) Pakeman et al. (2000) Gardiner & Dackombe (1983) Brassington (1988) Peterken (1980, 1981, 1996) Golterman et al.(1978) Bullock (1996) Peterken & Backmeroff (1988) Harper et al.(1995) Byrne (1991) Pooley & Jones (1996) Hellawell (1978, 1986) Cottam & Curtis (1956) Raven et al. (1997, 1998a) Holmes (1983) Dargie (1992) Reid & Quarmby (2000) Holmes et al.(1998, 1999a) Dawkins & Field (1978) Robertson (1999) Hynes (1970) Environment Agency (2003) RSPB/EN/ITE (1997) Klapper (1991) FAO (1977) Shaw & Wheeler (1995) Mackereth et al. (1978) Ferris-Kaan & Patterson (1992) Sheldrick (1997) Mainstone et al. (1993) Fuller et al. (1994) Sykes (1981) Mason (1991) Gilbert & Gibbons (1996) Thomson et al. (1993) Metcalfe-Smith (1994) Gilman (1994) Wadsworth & Treweek (1999) Moss (1998) Goldsmith (1991) Ward & Robinson (1990) NRA (1992, 1994a,b) Grant et al. (1997) Warren & Olsen (1964) Palmer (1989) Greenwood (1996) Palmer et al. (1992) Haines-Young et al. (2000) Parr (1994) Hamilton (1975) METHODS FOR SPECIES Petts (1983) Hodgson et al. (1995) ASSESSMENT (CHAPTER 10) Raven et al. (1997, 1998a,b) Hope-Jones (1994a,b) See the following references: RSPB/NRA/RSNC (1994) Horsfall & Kirby (1985) Stirling (1985) Huntings Surveys and Consultants Anderson et al. (1983) Vollenweider (1968) Limited (1986) Bibby et al. (2000)

# RPS Group plc and Scottish Natural Heritage 2005. 520 SOURCES OF FURTHER INFORMATION

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MONITORING TERMS AND ACRONYMS

Attributes Characteristics, qualities or properties of a GIS Geographical Information System. feature that are inherent in, and inseparable from, that GPS Global Positioning System (Appendix 5). feature (CCW, 1996). For species these may include Habitats Directive Council Directive 92/43/EEC (1992) population size, structure, habitat requirements, on the Conservation of Natural Habitats and of Wild distribution and other parameters. Attributes of Flora and Fauna. habitats may include key species, composition, Heterogeneous Describes an area that comprises blocks structure, supporting processes and other of different habitat types (e.g. a mosaic of heathland and parameters. scrub). BAP Biodiversity Action Plan. Homogeneous Describes an area that is uniform (e.g. an Birds Directive Council Directive 79/409/EEC (1979) on expanse of blanket bog). the Conservation of Wild Birds. Interest feature See feature. CCW Countryside Council for Wales. JNCC Joint Nature Conservation Committee. CMS Countryside Management System. Limits Threshold levels set with the intention of Common Standards Monitoring The common triggering management action. In the context of site standards agreed by the UK statutory conservation monitoring, they are judgements on the range of agencies and the JNCC for monitoring the condition of fluctuations in condition that an interest feature is SSSIs, Natura 2000 and Ramsar sites consistently likely to exhibit at a particular site. These limits are (JNCC, 1997). The term originates in the Environmental intended to account for any normal cyclic change, Protection Act 1990, which specifies ‘special functions’ which an interest feature might exhibit but which to be discharged through the JNCC, including the should not normally give cause for concern. establishment of common standards throughout Great Britain Monitoring Surveillance undertaken to determine the for the monitoring of nature conservation ... and for the extent of compliance with a predetermined standard or analysis of the resulting information (Environmental the degree of deviation from an expected norm (after Protection Act 1990, Article 133). Hellawell, 1991). Condition The term used to describe a range of states Monitoring unit Part of one feature; features may be through which the feature of interest may fluctuate separated into monitoring units on the basis of naturally within a particular site, and within which it is variation in tenure, management measures or likely to maintain or improve its status in the long term. topography. Each monitoring unit should be part of Acceptable condition is defined by the objective set for only one feature. the feature in question. Natura 2000 The Natura 2000 network is a series of EIA Environmental Impact Assessment. protected areas established under the EU Birds Directive Feature A habitat, habitat matrix, species or species or the EU Habitats Directive. (See SPAs and SACs.) assemblage occurring on a site. NVC National Vegetation Classification. Formulated standard A baseline state or objective Objective A statement of the nature conservation position; an absolute value or acceptable range. aspirations for the features of interest on a site,

# RPS Group plc and Scottish Natural Heritage 2005. 552 GLOSSARY

expressed in terms of the condition that we wish to Surveillance An extended programme of surveys obtain for each interest feature. systematically undertaken to provide a series of Ramsar sites Protected areas designated under the 1971 observations to ascertain the variability that might be Ramsar Convention. The Convention seeks to promote encountered over time (but without preconceptions of the wise use of all wetlands, and to provide special what these might be). protection for wetlands of international importance. Survey A set of observations using a standardised Many Ramsar sites are also SPAs, classified under the procedure and within a restricted period of time, Birds Directive. without any preconception of what the findings RHS River Habitat Survey. might be. SACs See Special Areas of Conservation. Target A target specifies the range of states that an SCM See Site Condition Monitoring. attribute of a feature should attain if the feature is to SEPA Scottish Environment Protection Agency. be considered in acceptable condition, i.e. if the feature SERCON System for Evaluating Rivers for is to maintain or improve its status on that site in the Conservation. long term. Sessile Fixed in one position. Site Condition Monitoring An interpretation of STATISTICAL TERMS Common Standards Monitoring. It replaces what was formerly known as Site Integrity Monitoring (SIM), Accuracy The closeness of an estimated value to the true Site Quality Monitoring (SQM) and Loss and Damage value. Monitoring. Analysis of variance (ANOVA) A class of parametric Sites of Special Scientific Interest (SSSIs) Sites methods for testing differences between two or more notified under the Wildlife Countryside Act 1981, groups of samples. Tests compare the variability of the providing statutory protection for flora, fauna, or for data within the groups and between the groups. If the geological or physiographical features. As well as variability within groups is similar to the variability underpinning other national designations (such as between them, the groups could be drawn from the National Nature Reserves), the series provides same population. If not, there are likely to be differences statutory protection for terrestrial and coastal sites between the populations. See also Tukey test. that are important within Europe (Natura 2000 sites) Average See Mean. and globally (such as Ramsar Sites). SSSIs are the Bootstrapping A method for deriving estimates and main nature conservation designation in Great confidence intervals that does not make parametric Britain. assumptions about the distribution of the data. It is a SPAs See Special Protection Areas. resampling method with new samples drawn Special Areas of Conservation (SACs) Protected areas repeatedly from the dataset, with replacement. For each designated under the EU Habitats Directive (92/43/EEC). of these samples a new estimate is calculated, The Directive requires the establishment of a European generating information about the distribution of the network of sites that will make a significant contribution attribute being measured. If many resamples are drawn to conserving habitats and species (excluding birds) and a 95% confidence interval is required, the considered to be most in need of conservation at a resampled estimates are ordered from smallest to European level. largest and the interval limits are such that 5% of Special Protection Areas (SPAs) Strictly protected estimates fall outwith the limits. sites classified in accordance with the EU Directive on Chi-squared test (c2) A statistical test that can be used the conservation of wild birds (79/409/EEC), also known for homogeneity, randomness or goodness of fit. The as the Birds Directive. They are classified for rare and test compares observed frequencies with expected vulnerable birds, and for regularly occurring migratory frequencies derived from the null hypothesis.If species. observed frequencies differ significantly from those SSSIs See Sites of Special Scientific Interest. expected, the null hypothesis is rejected. The chi- Standard See Formulated Standard. squared test can be used for testing for significant Statistical terms 553

changes in plant frequency data over time and for example, to estimate the population standard deviation, testing whether a dataset is distributed according to a we first need an estimate of the mean, so the degrees of probability distribution (e.g. normal, Poisson), i.e. as a freedom are therefore n 1. goodness-of-fit test. Descriptive statistics A numerical summary that Cochran’s test of linear trend The standard chi- concisely describes the properties of the observed squared test gives the same result regardless of the frequency distribution (e.g. mean and standard order of the rows and columns. Cochran’s test of linear deviation). trend (or Q-test) is more suitable for detecting trends Distribution The spread of observations of a variable across an ordered set of categories (e.g. years). over the range of measurement. Distributions are Coefficient of variation The standard deviation generally expressed in terms of the probability of a divided by the mean (often multiplied by 100 and variable taking each value in its range or of being less expressed as a percentage). This is useful for comparing than that value. variability between samples from populations with Errors, Type I and II In statistical testing, a Type I error different means or units. is the rejection of a null hypothesis when it is true. A Confidence intervals When a measurement, such as Type II error is the acceptance of a null hypothesis when percentage cover of a species, is estimated from a it is false. sample, the confidence interval is a range of values Fisher’s exact test A useful alternative to the within which we have some confidence the chi-squared test for assessing independence in 2 2 measurement for the whole population lies. A 95% tables that have small expected values. The test calculates confidence interval is such that if many samples were the exact probability that the observed table, or one taken then we would expect 95% of the confidence showing a more extreme departure from independence, intervals calculated from these to contain the would arise by chance. An example would be population measurement. 95% is by far the most presence–absence data collected on two occasions. common level of confidence used. Testing whether the proportion of presences has changed Correlation If two variables are correlated then one is is equivalent to testing independence between time and related to the other. For example, soil moisture is the number of presences. correlated with soil organic matter content: a soil Friedman test A non-parametric test that compares with a high organic matter content will also tend to three or more paired samples. have a high moisture content, and vice versa. Goodness-of-fit tests Tests of hypotheses about Correlation can be positive or negative. Correlated frequency or probability distributions. An example is variables are not independent. See also correlation the chi-squared test, which examines the goodness of coefficient. fit of our observed frequency distribution to the Correlation coefficient An index of the degree to expected frequency according to our hypothesis. which two variables are related, which can be tested for Goodness-of-fit tests can be used to test for randomness, statistical significance. It varies between 1 (complete or for conformation to a theoretical probability negative correlation) and þ1 (complete positive distribution. These tests can be used for continuous correlation). variables: in this case it is necessary to group classes Degrees of freedom A number used in many statistical together as a histogram, thus making a frequency tests that is based on the number of observations (n)ina distribution. sample and the number of estimated parameters. For G-test An alternative test to the chi-squared test, also example, if we are told that a sample has 5 observations known as the likelihood ratio test. The G-test and a mean of 50 and are asked to invent values for the supposedly has theoretical advantages over the observations, we can pick any four numbers, but the chi-squared test. However, the chi-squared test is more fifth number is fixed by the choice of the first four. The commonly used. number of degrees of freedom is therefore n 1, in this Independent observations Observations in which the case 4. If the formula for estimating a parameter itself value of one observation is not inherently affected by contains an estimate, a degree of freedom is lost. For that of another. 554 GLOSSARY

Independent variables Variables for which the value Ordinal variable A measurement comprising a set of of one variable is not inherently affected by the value of ordered categories. For example, abundance of a species another variable. might be recorded as ‘rare’, ‘occasional’, ‘frequent’, etc. Kruskal–Wallis test A non-parametric test for Parametric tests Statistical tests that involve the comparing the distributions of more than two unpaired assumption that the data follow a particular samples. distribution, usually normal. See also non-parametric Likelihood ratio test See G-test. tests. Mann–Whitney test A non-parametric test used to Percentage relative precision The difference between compare the distributions of two unpaired samples. the mean of a sample and its 95% confidence McNemar’s test A chi-squared test of symmetry used intervals, expressed as a percentage of the estimate. for paired samples in which the measurements are Percentiles The values that divide a set of measurements ordinal. A significant result indicates a greater change into 100 equal parts. Thus the 25th percentile will be the in one direction than in the other. value that 25% of measurements fall below. The 25th Mean A measure of central tendency or of a typical value, percentile is also known as the first quartile. calculated as the sum of a set of observations divided by Population Any collection of individual items or units the number of observations. that is the subject of investigation. The population is the Median The middle observation in a set of observations total number of units, from which we usually take that have been ranked in magnitude. An alternative samples. measure of central tendency. Precision The closeness of the sample measurements to Mode The most common value in a set of observations. each other. An estimate is more precise if it has a smaller Another measure of central tendency, though rarely standard deviation. used. Probability A measurement of the likelihood of a Nominal variable A measurement comprising a set of certain outcome of an event taking place, measured on a categories whose ordering is arbitrary. For example, scale from 0 (impossible) to 1 (inevitable). The sum of the habitat classifications are usually nominal as they have individual probabilities for all possible outcomes of an no natural ordering. event is equal to 1. Non-parametric tests Usually refers to tests based on Probability distribution A breakdown of the ranks. Non-parametric tests are ‘distribution-free’, i.e. individual probabilities of all possible outcomes. Can be they do not require the same assumptions as generated empirically (by measurement) or by a parametric tests. They are usually less powerful than mathematical model (e.g. normal, binomial). If it can be parametric tests, i.e. less likely to detect a real departure shown that data agree well with a predicted probability from the null hypothesis. distribution, we can make generalisations and Null hypothesis The basic starting hypothesis for a predictions about the data. On the other hand, if statistical test. For example, the null hypothesis may be collected data do not agree with a predicted that there is no difference between the populations distribution, we may have cause for rethinking our from which samples have been drawn. This is rejected if initial hypothesis. the test produces a significant result. Q-test See Cochran’s test of linear trend. Observation A record (e.g. measurement of height, Quartiles The values that divide a set of measurments count of numbers) taken from a sample unit. into four equal parts. A quarter of measurments will be One-sided/two-sided test A one-sided test tests below the first quartile and three-quarters are below the whether a statistic is specifically larger or smaller third quartile. see also Percentiles. than that given in the null hypothesis. A two-sided Regression Regression analysis produces an equation test merely tests whether the statistic is different that links two (or more) variables, which can be used for from that given in the null hypothesis. In most cases predictions (i.e. for a given value of x, predict the value of a two-sided test is required, unless a one-sided y) or to examine the relationship between variables. If hypothesis has been specified in advance of the one variable is time, regression can be used to test for survey. trends. Regression can be linear (a straight-line Statistical terms 555

relationship) or non-linear (a relationship between two unpaired data. Larger samples give results similar to or more variables of a more complex form). those of the z-test. Sample A subset of the units in a population that Time-series analysis A group of techniques for represents the population as a whole. If a sample is to be analysing fairly long time series. Can be used to examine truly representative, the sample must be drawn cyclical patterns and correlation over time, and for randomly from the population. predictive modelling. Sample unit An individual unit from a sample. A set of Transformation Transforming data by a mathematical these forms a sample. function, for example to make a data set approximate a Standard deviation A measure of the variability of data normal distribution more closely. in terms of the difference of observations from the Tukey test Test performed with analysis of variance mean of the population (or sample) from which they (ANOVA), which, in the event of a significant result, are taken. establishes which samples are significantly different Standard error The standard deviation of the from each other. sample mean. Calculated as the standard deviation Two-sided test See one-sided/two-sided test. divided by the square root of the sample size. Type I error, Type II error See errors, Type I and II. Statistical significance Arbitrary thresholds of Variable A characteristic of a population that differs significance are set for the outcomes of statistical tests. from individual to individual (e.g. length, mass, height, A significance level of 5% means that the result is taken cover, etc.). to be significant if there is only a 5% probability that the Variance The square of the standard deviation. result occurred when the null hypothesis is true. This is Another measure of the variability of the data. commonly written as P < 0.05. See also errors, Wilcoxon signed rank test A non-parametric test Type I and II. for comparing two samples of paired data. t-test A parametric statistical test used to compare the z-test A parametric test for comparing means of two means of two samples; can be adapted for paired or large samples. Index

abstraction expertise 166, 167 mats 300 fens 129 field checking 171 monitoring 295–6, 297 rivers 139–41 grazing effects 238 planktonic density 296 abundance habitat population size 296 aquatic invertebrates 362 area calculation 172 presence–absence 296 birds 415, 416–17, 423 classification 168, 169, 170 quadrats 296–9, 300 DAFOR scale 20, 134, 138–9 identification 168 species of conservation importance fish 378 interpretation repeatability 172–3 300–1 stocks 368, 369 mapping 167, 171 survey time 298 habitat estimate 183 methods 165, 171 surveying 295–6, 297 insects 355, 356 mosaics 168, 169 transects 296–9 macrophytes 138–9 objectivity 166 water or substrate sampling Malaise traps 356 Phase I habitat mapping 182, 186 299–300 mini-quadrats 211 sampling 171 alien invasive species 302 objectives for species 13 uses 166–7 alternative hypothesis 41 protected areas 83 African–Eurasian Migratory amphibians reptiles 407, 408, 408–9 Waterbird Agreement 75, 427 attributes for assessing condition trapping web estimates 267 African–Eurasian Waterfowl 387–8 typical species 10–12 Agreement 70 behaviour 391–2 see alsoDAFOR scale of abundanceAgreement on the Conservation of bottle traps 392–4, 393 abundance index Bats in Europe (1994) 447 breeding success 387, 394, 397–8 infinite-width transects 265 Agreement on the Conservation of conservation evaluation criteria mammals 464 Populations of European Bats 401–3 acid deposition/acidification (EUROBATS) 75 conservation status in UK 402–3 limestone pavement 125 agricultural management practices data analysis and interpretation montane habitats 141–2 119 bottle traps 394 adaptive sampling 36 agrochemicals 119–20 egg searches 399 Adders 404, 406, 408 air pollution mark–recapture technique 401 conservation status 411 blanket bog 144 netting 395 handling 409 heathland 127 pitfall traps 397–8 aerial photography 19, 158, 165 limestone pavement 125 torch counts 392 advantages 173 montane habitats 141–2 transects 398 analysis 167 raised bog 131 dispersal 388 bias 166 airborne scanning systems 167 egg searches 398–9 burning monitoring 241–2 airlift sampler 364 juveniles 387, 388 change monitoring 166, 172–3 Alcian blue dye 379 larvae 394 checkerboard design 172–3 algae mark–recapture techniques 399–401 comparisons between photographs attributes for assessing condition metamorphs 387, 388, 397–8 172–3 296 monitoring 387, 389 data benthic 299–300 mortality 388 analysis 165–6 community composition 296 netting 394–5 storage 171 data PIT tags 400–1 demographic techniques for analysis/interpretation 299, 300 pitfall traps 395–8, 396 vascular plants 316 recording 298 population decline 403 disadvantages 174 epiphytic 299–300 population size 387 efficiency 166 field methods 298, 299–300 class assessment 402 equipment 165, 166, 167 filamentous 301 protection status in EU and UK digitising 167 identification 298 401–2 Index 557

recruitment 397–8 colonies 438 bat boxes 433, 441–2 safety precautions for surveys392 conservation Bat Conservation Trust 433, 447–8 site designation criteria403 evaluation criteria 446–9 bat detectors 433, 438–9, 440 SSSI site selection scoring system status 436, 447–8 heterodyne 443 403 counting techniques 438–9 batch-marking 269, 409 surveys 387 counts beam trawls 382 methods 388–401 , 389 bat boxes 441–2 belt transect 35 survival 388 stopping 439 Bern Convention 75–6, 473–7 terrestrial habitats395 data analysis and interpretation aquatic invertebrates 366 terrestrial transect searches398 440, 441, 442, 444, 445, 446 bats 446–7 torch counts388 –92 Daubenton’s 436, 438, 444, 448 birds 427 trapping webs395 dispersal routes 433 butterflies 333 analysis interpretation6 2–3 droppings 445, 445 fish 385 analysis of variance (ANOVA) emergence counts 433 implementation in UK 77–8 55, 552 feeding habits 433 mammals 469 animal welfare46 field methods 438–9, 440, 441, 442, terrestrial invertebrates 357 aquatic environment 443–4, 445, 446 bias 21–3 monitoring in295 foraging 445–6 aerial photography 166 plant assemblages139 Greater Mouse-eared 446, 447 cluster in point transects 261 safety 295–6 Grey Long-eared 436, 448 observer in vascular plant surveys arcsin transformation62 hibernacula 438, 441, 448 304 area-frame samplingsee sampling, hibernation counts 440–1 plotless samples 234 stratified Horseshoe 436, 441, 443, 446, point transects 261 Area of Search (AOS), butterflies 447, 448 binomial distribution 38–40 334 identification 441, 446 biodiversity artificial substrates Leisler’s 436, 448 evaluation 65 aquatic invertebrate36s 4–5 maternity colonies 433–8, 446 Biodiversity Action Plan (UK BAP) 68, see alsorefugia , artificial monitoring 433, 434 101, 245 Association of British Fungus national schemes 438, 441, 443 bat protection 447, 448 Groups 277 Natterer’s 436, 440, 443, 448 birds 429 Atropos 339 Noctule 436, 448 Broad Habitats 171 augers 196 nursery colonies 433–8 use 248 autocorrelation 60 oil stains 445 bryophytes 293 Pipistrelle 436, 443, 447, 448 butterflies 333, 333–4 Badgers 465–6 population dragonfly protection status 327 bait marking 466 changes 438 fish 386 hair tubes or catchers 460 estimates 438 fungi 277 latrines 466 size 442 habitat setts 455, 466 protection status in EU and UK evaluation 246, 248 survey timing 466 446–7 lists 79–80 territory 458–9 radio tracking 445–6 types 107, 171 Badgers Act 469–71 remains 445 lichens 286 bait for trapping 461–2 roosts 445–6 macromoths 340 bait marking exit counts 438–40 mammals 469–71 Badgers 466 numbers 433–8 Pool Frog 402 mammals 458–9, 466 protection 445 Priority Habitats 80, 248 banks sites 444 categories 478–89 earth 118–19 scratch marks 445 Priority Habitats and Species lists grassland 117 Serotine 436, 448 78, 246 stone 118–19 site designation criteria 448–9 vascular plants 320 banner nets 383 site evaluation 446 Priority Species 80 bar chart 60 county/regional 448 reptiles 410 Barn Owl 420 local 448–9 terrestrial invertebrates 357 bat(s) national 448 vascular plants 318, 320 activity surveys 433 surveys 433 Biodiversity Convention 79–80 attributes for assessing condition methods 434, 438–46 Biogenetic Reserves 89, 473–7 433–8 timing 439 Biological Monitoring Working Party Barbastelle 436, 442, 446, swarming counts 440 (BMWP) score system 362 447, 448 torch counts 444 Biosphere Reserves 88–9 Bechstein’s 436, 442, 447, 448 transects 440, 442–4 biotic scores for water quality 362 Brandt’s 436, 446, 448 urine stains 445 birds Brown Long-eared 436, 448 Whiskered 436, 446, 448 abundance 415, 416–17, 423 558 INDEX

birds (cont.) monitoring 143–5 population size 288–9 attributes for assessing condition quality attributes 145 presence–absence 288 412–13 surveys 143–5 protection status in EU and UK 293 Bern Convention427 bog, lowland raised quadrats 291 Bonn Convention427 monitoring 130–1 recovery following burning 242 breeding colony census413 quality attributes 131 short-term 288 breeding pairs418 survey 130–1 site designation criteria 294 clutch size41 2–13 bog woodland 109–11 species evaluation at site 293 conservation 68 Bonn Convention 75, 427, 473–7 surveying 288, 290 evaluation criteria42 2–32 bats 447 total counts 289 site interest423 bootstrapping 56–7, 61, 552 transects 291 status 71 regression model parameters 60 visual estimates 289–91 constant-effort trapping and Botanical Society of the British Isles burning 240–2 ringing 417–18 (BSBI) 318 aerial photography 241–2 data analysis and interpretation bottle traps 392–4 blanket bog 144 413–15, 416–17, 418 construction 393 erosion 243 distance sampling417 placement 393–4 geographical extent monitoring distribution 415 timing 394 241–2 dye marking413 boxes 364, 365 heathland 126–7 European Species of Conservationboxplots 51, 52 immediate effect evaluation 242 Concern 428–9 Braun–Blanquet scale 204, 206, 207 impact 241 field methods413 , 415–16 bryophytes 291 intensity flightline surveys418 Breeding Bird Survey 412, 415 determination 242 line transects41 6–17 breeding success indicators 241 mark–recapture techniques41 3, amphibians 387, 394, 397–8 monitoring 241 418 birds 412–13 methods 241–2 migratory 412, 419, 423 reptiles 404 sea cliffs 146 waterbirds 427, 428 British Basidiomycete Checklist 277 upland grassland 124 mortality 413 British Bryological Society 292–3 vegetation recovery following 242 monitoring 418 British Dragonfly Society 327 burrows nocturnal surveys41 9–20 British Lichen Society 286 mammals 455 point counts417 lichen Biodiversity Action Plans Manx shearwater 60 population 286 butterflies international importance71 British Mycological Society (BMS) 277 abundance 329 long-term trends415 British Trust for Ornithology (BTO) adult counts 332 size 412 412 Area of Search 334 presence–absence 417 Broad Habitat types 171 attributes for assessing condition productivity 412–13, 418 changes 180 328–9 protection status in EU and UK LCM2000 Class relationships 163–4 breeding areas 328 427–32 use 248 colony numbers 328 radio tracking419 browsing conservation recording in flight416 impact monitoring 237–40 evaluation criteria 333–4 ringing 413 , 417–18 intensity 119 status in UK 333–4 satellite tracking419 monitoring methods 238–40 data analysis and interpretation seabird surveys at 419sea bryophytes 331, 332 spatial distribution412 attributes for assessing condition egg counts species assessment criteria423 288–9 quadrats 331–2 survival 412 –13, 418 conservation timed counts 329–31 territory evaluation criteria 292–4 transects 331–2 counts 416 status 293–4 European Red List 76 mapping 415–16, 418 cushion-formers 288 field methods 329–31, 331–2 threatened species 427 counts 289 larval counts total counts 413–15 data analysis and interpretation quadrats 331–2 trapping 417–18 289, 291, 291, 292 timed 329–31 wetlands 427 ephemeral 288–9 transects 331–2 wing tags 413 epiphytic 288 larval population see alsoImpor tant Bird Areas (IBAs) field methods 289, 291, 292 estimates 332 Birds Directive (EU) 76, 427, 427–8, identification 289, 490–1 size index 329–31 473–7, 551 mat-formers 288 life cycle 328–9, 331 bog, blanket monitoring 288, 290 monitoring 328, 330 habitat condition assessment methods 289–92 occupancy area 328 143–4 photography 291–2 population Index 559

patterns 329 coefficient of variation26, 553 correlation coefficient5 1, 553 range 328 collars, mammal marking463 counters size 328 collision/mortality surveys418 automatic for fish375 structure 328–9 colour coding, habitats171 , 181 hand-held 439 presence–absence 328, 329 Common Bird Census415 counting 19 protection status in EU and333 UKCommon Standards Monitoring twice 260– 1 site designation criteria334 (CSM) 107, 551 Countryside Rights of Way Act 2000 surveys 328, 330 bryophytes 294 (CROW Act)7 8, 245– 6 frequency 331 framework 94 amphibians 401 methods 329–32 fungi 278 bats 446–7 timed counts32 9–31 Guidance for Mamm449als birds 429 timed searches32 9– 31 Community Conservation Index (CCI)butterflies 333 transects 328 84, 367 dragonfly protection status327 adult counts332 Compact Airborne Spectrographic fungi list278 Butterfly Monitoring Schem333e Imager (CASI)158 lichens 286 methods 332, 343 complementarity, protected areas macromoths 339 82–3 protection 466 cameras and camera systems confidence intervals3 9–40, 51–2, reptiles 410 35mm single-lens reflex174 , 175 61, 553 terrestrial invertebrates357 aerial film15 6–8 back-transformed 61 vascular plants320 digital 156–8 , 175 calculation 57 Countryside Management System infrared 419–20 small sample size57 (CMS) 49 canals 132 conservation Countryside Survey (ITE)171 CANOCO program19 2, 193 genetic diversity factors72 counts canopy importance evaluation criteria87 fungi 272 composition 223 objectives 68 systematic total of vascular plants gaps 227 priority setting6 8–72 312–14 position 226 status 70 field methods31 2–13 spread 227 United Kingdom24 6–50 time for point transects263 CAPTURE program26 9–70, 401 Conservation of Natural Habitats timed searches258 captures and of Wild Fauna and Floracounts, total257 mark and release267 see Habitats Directive analysis 257 mark–recapture techniques Conservation of Wild Mushrooms methods 257 268–70 Code of Practice277 County Wildlife Sites249 removal methods268 Conservation (Natural Habitats & coverc.) reptiles 409 Regulations (1994)77 , 401–2, 466 habitat 11 trapping webs267 mammals 469 point quadrats217 carr habitat12 8–30 reptiles 410 cover-abundance 221 categorical data5 7–9 , 58 Conservation (Natural Habitats & Criticallyc.) Endangered category central limit theorem53 (Northern Ireland) Regulations 73–4 change, change monitoring (1995) 77 culling records463 aerial photography16 6, 172–3 Convention of Migratory Species ofcyclical behaviour detection60 dataset 173 Wild Animals70 cylinder sampling of aquatic nested quadrats for 216FIBS Convention on Biological Diversity invertebrates 364 NVC surveys193 (1992) 473–7 Phase I habitat mapping180 Convention on International Trade DAFORof scale of abundance20, 13 4, rate of15 Endangered Species of Wild 138–9 validation 173 Fauna and Flora (CITES)473– 7 bryophytes 289, 291 charophytes see stoneworts mammals 469 ground vegetation206 chi-squared tests5 8–9, 552–3 Convention on the Conservation of NVC surveys189 circular plots, fixed radius266 European Wildlife and Natural quadrat use20 4, 206 clearance plots45 6, 457 Habitats see Bern Convention shrub vegetation206 cliffs, maritime14 5–7 Convention on the Conservation ofdamselflies see dragonflies and clothing 47 Migratory Species of Wild damselflies Clover trap461 Animals see Bonn Convention Dartford Warbler 422 cluster bias, point transects261 Convention on Wetlands of data cluster sampling3 4–5 International Importancesee analysis 49–50, 53, 55 clusters, data264 Ramsar Convention satellite-based remote sensing clutch size41 2– 13 Co-ordinated Information Network 161 coastal defences and protection on the Environment (CORINE) software 64 saltmarsh 152 161 steps 41 shingle above high 148tide corrals 461 backing up 48 560 INDEX

data (cont.) trapping 461 cover values193 categorical 57– 9 tree damage230 ground/shrub vegetation20 6, 208 clusters 264 demographic techniques for vascularDormouse 455, 458, 466–8 collection 155 plants 307, 315– 17 distribution 468 measures 20 aerial photography316 habitat 466 number of locatio20ns data nest boxes or tubes466– 7 , 468 time of40 analysis and interpretation317 nests 468 comparison 51 recording 316 –17 presence–absence 468 conversion to informati155on field methods31 6– 17 protection 466 description 50–1 mapping 316 weighing 468 direct measure20s maps 317 dot plots51 displaying 50–1 marking of plants316 dragonflies and damselflies distribution 52 density, species11 attributes for assessing condition exploring 50 density estimate255s 322 holding 48–9 aquatic invertebrate36s 0, 364 behaviour 325 indirect measures20 artificial refugia35 6, 357 conservation integration 49 distance sampling26 0–1 evaluation criteria327 management 48–9 faecal pellet counts456 status in 327UK many zeros, with60– 1 fish 377, 381 data analysis and interpretation nominal 51 mammals 455, 459 325, 326 normal distribution4 3–4 minimum 258 exuviae counts32 4–5, 326 ordinal 51 Red Squirrel469 frequency and timing324 –5 paired 54 reptiles 407 field methods32 4– 5, 325–6 presentation 50–1 strip transects26 5–6 identification 324 software 64 detection function, distance larval sampling324 quality 27 sampling 263–4 larval skins324 –5 quantitative 20, 51, 54 development, structural, vegetation life cycle322 , 325 recording 46 impacts 244 monitoring 322, 323 for algae and aquatic Dietrick samplersee D-vac suction population macrophytes 298 sampling range 322 remote sensing155 digestibility of plants238 size 322 skewed distribution61 digital imagery155 structure 322 storage 48 digital photogrammatic device recruitment 322 summarising 50, 50–1 168 site designation criteria327 transformation 61–2 digitisation of maps183 surveys 322, 323 types 20 digitising equipmen167t methods 322–6 unpaired 54 distance interval26s 3–4 timed counts326 users’ requirements159 distance sampling transects 325 –6 uses 27 analysis 263– 4 drainage Data Deficient category74– 5 birds 417 blanket bog144 databases 48, 48–9 data 264 fens 129 dataloggers with infrared light density estimates26 0–1 dune systems179 beams 439 detection function263 –4 erosion 243 dead wood surveying and monitoringdetection of objects260 dunging, nutrient cycling238 234–6 distance bands26 2–3 D-vac suction sampling353 advantages 236 measurement accuracy260 , 261 data analysis236 methods 255 , 260–4 ear tags463 disadvantages 236 mobile species263 Eastern Scotland Index of Ecological expertise 235 point transects26 0, 261, 263 Continuity (ESIEC)285 field methods235 –6 principles 260–1 lichens 285 index 236 random distribution260 echolocation 443 problems 236 sample sizes264 ecological evaluation framewo65rk repeated 235, 236 transects 260 , 261, 262–3 ecological value of protected areas time efficiency234 Distance softwar26e 3–4, 417 81–2 uses 234 ditches 117 ecosystems DECORANA program19 2, 193 , diversity, protected area selection functions 67 300, 362 83–4 identification of valuable deer DNA fingerprinting components 65–8 faecal pellet counts456 faecal pellet counts457 see alsoValuable Ecosystem grazing 238–9 otters 465 Components Red 230 Domin scale1 1, 204, 206, 207 edge effects 226 transects 460–1 bryophytes 291 EECONET 473–7 Index 561

egg searches Eu-Oceanic Woodland Index of supplementary for grazing animals amphibians 398–9 Ecological Continuity (EuOIEC) 237–8 frogs 399 285 transects for Red Squirrel 468–9 newts 399 European Diploma (1965) 473–7 fen habitat toad 399 European Red Lists 76 management 129 egg sticks, newt399 European Species of Conservation monitoring 128–30 electrofishing 268, 383, 383–4 Concern (SPECs) 428–9 nutrient status 129 electronic counters, fish376 , 377 European Union survey 128–30 emigration 13–14 amphibian protection status topography 128 England Biodiversity Strategy78 401–2 fences, pitfall traps 395–7 English Nature aquatic macrophyte protection reptiles 408–9 conservation programme for status 302 ferns, identification 491 vascular plants318 –19 bat protection status 446–7 fertilisers 119–20, 123 grazing index240 bird protection status 427–32 FIBS program 192 Enhanced Thematic Mapper (ETM) bryophyte protection status 293 fields, strips adjoining 117 156 butterfly protection status 333 fieldwork Environment Agency dragonfly protection status 327 equipment 47, 498–518 Community Conservation Index84 fish protection status 385–6 health and safety issues 46, 47–8 River Habitat Corridor Surveys86, fungi protection status 277–8 fin clipping 379 139 habitat protection status 245–6 finite population correction 27 Environmental Impact Assessment lichen protection 285–6 fish (EIA) macromoth protection status abundance 378 bird studies415 339–40 adult spawning 375 key species420 –2 mammal protection status attributes for assessing condition specific methods41 8–20 469–71 368–75 evaluation criteria9 7–101 reptile protection status 410 bankside counts 375–7 high conservation priority species/ terrestrial invertebrate protection baskets 378–9 habitats 67 status 357 breeding success 369–75 monitoring 3–5 vascular plant protection status catch returns 377–8 planning applications244 319–20 trends 378 scoping exercise9 6–7 eutrophication censuses 369 site evaluation9s 6– 101 soil 238 conservation statutory designations249 standing open water 135–6 evaluation criteria 385–6 surveying 3–5 Extinct category 73 status in UK 386 Valuable Ecosystem Components Extinct in the wild category 73 counting methods 375 67, 246 extinction data 377, 377–8, 385 environmental impact monitoring global 68 analysis and interpretation 237 national level 68 376–7, 378, 379–80, 381, Environmental Statement (ES)244 risk 68 382, 383, 384 Environmentally Sensitive Areas objective assessment 73 direct counts 375–7 (ESAs) 213 populations 70–1 estimates 369 erosion field methods 375–6, 377–9, 380, grazing impact238 faecal pellet counts 381, 382, 383, 384 marker placing24 3–4 accumulation rate assessment 457 gill netting 380 monitoring 243–4 density estimation 456 identification 381 impact 237, 243 genetic markers 457 lift netting 383 methods 243–4 mammals 456–7 likelihood of capture 377 rock faces243 population size estimation 457 marking 379, 381 saltmarsh 150–1 , 152 quadrats 456–7 mark–recapture techniques 375, sand dunes150 rabbits 455 378, 379, 381 sea cliffs146 transects 456–7 migratory 378 soil profiles243 farmland boundary features monitoring 268, 368, 369, 370 vegetation loss243 117–21 point counts 376 vegetation recording244 external impacts 119–20 pots 378–9 error types 21, 41, 553 habitat condition assessment protection status in EU/UK 385–6 estimates 23 117–19 push netting 383 EU Directives management requirements recapture frequency 379 Birds 76–7 119–20 recruitment of juveniles 369 Bonn Convention 75 monitoring 117–20 sampling 369 Habitats 76–7 fauna, woodland 108 scales 369, 380 see alsoBirds Directive (EU); feeding seine netting 380 Habitats Directive (EU) signs of mammals 458 semi-quantitative surveys 384 562 INDEX

fish (cont.) fungi 271–8 gravel pits132 species composition368 attributes for assessing conditiongrazing surveys 368, 370 272 associated fauna238 equipment 382 conservation blanket bog144 methods 369, 375 –84 evaluation methods27 6– 8 effects 238 throw netting383 status in 278UK erosion 243 transects 376, 377 data analysis and interpretation grassland habitats23 8–9 trawl netting38 1–2 274, 275, 276 heathland 126–7 underwater counts37 6, 377 direct searche27s 2–4 monitoring 238– 9 fish passes369 distribution 276 impact monitoring23 7–40 fish stocks EU protection status277 –8 intensity 119, 124 abundance 369 field methods27 2– 4, 275–6 limestone pavemen125t condition 368 –9 fixed-point photography27 5–6 land managemen239t fish traps369 , 378–80 fruiting variability274 monitoring methods23 8–40 intercept 379–80 habitat condition272 plants non-intercept 378 identification 271–2 digestibility 238 permanent 379 long-term trends271 palatability 238 fisheries monitoring 271–2, 273 saltmarsh habitat152 catch data37 7–8 population size272 sand dunes150 catch returns37 7–8 quadrats 274–5 seasonal regimes23 7–8 management for rivers141 site designation criteria278 stocking levels23 7–8 flightline surveys418 transects 275 –6 wild animals238 –9 flood defences, rivers141 UK protection status277 –8 grazing index (English Nature)240 floodplain woodland10 9–11 fur clipping463 grids 313 forest fyke nets37 8–9 terrestrial invertebrates34 4– 8 operations 109 ground vegetation stand 111–12 galvanotaxis 383 cover estimates203 seedlings 112 game bags46 3, 464 frequency methods204 see alsotrees ; woodland habitat Brown Hares469 height 210 forestry stock maps114 Garden Butterfly Count333 individual total counts202 Foxes gastropods see slugs; snails advantages 208 dens 455 generalised additive models60 analysis 207–8 hair tubes or catchers460 genetic diversity1 5, 72 cover estimate205s fragmentation 12, 14 genetic markers field methods20 5–7 FRAGSTATS spatial analysis program faecal pellet counts457 problems 206 172 Otters 465 quadrat size205 frequency geographical information systems sampling strategy205 quadrat measures258 –9, 259–60, (GIS) 49, 183 time efficiency204 493 gill netting380 uses 201 species 11 global positioning systems (GPS)496 structure 210 statistical methods260 grapnel surveys for aquatic temporal niches206 frog(s) macrophytes 20–1, 199–201 see alsomini-quadrat s; quadrats amphibian terrestrial searches398 advantages 201 grouse moors, burning 240 egg searche399s analysis 201 Guidance on the Methodology for Multi- pitfall traps397 disadvantages 201 Modal Studies (GOMMMS) 97 Pool 402, 403 field methods20 0– 1 gulleying, erosion 243 population time efficiency199 decline 403 grasses, identification124 habitat(s) peak 392 grassland habitat abundance estimate 183 spawn clumps398 , 399 banks 117 area torch counts392 condition calculation 172 Froglife assessment 121–, 124–2 monitoring 6 Key Reptile Sites411 definition 122 change mapping 178, 185 reptile population size class411 cover 122 classification 168, 169, 171 Functional Interpretation of external impacts12 2–4 Common Standards Monitoring Botanical Surveys (FIBS), nested grazing monitoring23 8–9 107 quadrats 212–12 litter 122 composition 10–12 expertise 213–14 management requirements12 2–4 conservation field methods214 –16 monitoring 121–4 evaluation criteria 245 time efficiency213 quality attributes123 importance 246 Fungal Records Database (BMSFRD) sward height122 priority lists 72–80 277 undergrazing 238 status 70 Index 563

cover 11 Great Crested Newts401 –2 definition 122 diversity 83–4 habitat evaluation246 cover 122 evaluation 246 Annex 247I –8 external impacts12 2–4 existing designation checks249 macromoths 340 management requirements12 2–4 fragmentation 12, 14 mammals 469 monitoring 121–4 high conservation priority67 Natterjack Toads401 –2 species identification 168 nomenclature relationship to BAP dispersal 122 indicator species10 priority habitat categories richness 122 aquatic invertebrates367 478–89 sward height122 international importance246 Special Areas of Conservation see alsoplant communities lichens 280, 280–2 , 284, 285 (SACs) 89 hibernation counts, bats440 –1 antiquity 284 terrestrial invertebrates357 histograms 51, 52, 61 health 284 vascular plants31 9–20, 321 hydroacoustic systems, fish counting micro-structural attributes12 Habitats of Community Interest76–7 375, 376 , 377 minimum size181 Habitats Regulations77 hydrology monitoring 105–6 hair tubes or catchers for mammalsblanket bog144 area 6 459–60 physical attributes195 attributes for8 –12 Red Squirrels468 rivers 139 methods 154 handling, reptiles409 shingle above high 148tide quality 6 Hare wetlands 128 units 17 Brown 469 woodland habitat10 9–11 protection status24 5–6 transects 460 hypothesis testing4 1–2 , 51– 2 rate of change15 hay meadow124s bootstrapping 57 richness 84 health and safety issues46, 4 7– 8 species requirements15 heather IKONOS satellite156 surveys 105–6 burning 240 immigration 13–14 general methods154 overgrazing 238 Important Bird Areas (IBAs)83, 429 trend detection5 9–60 regeneration 240 criteria for identification424 typical species10 heather moorland, grazing index240 Important Fungus Areas (IFAs)278 abundance 10–12 heathland report 277 Valuable Ecosystem Components air pollution127 site criteria278 67, 67– 8 burning 126–7 Important Plant Areas for Europe83 Habitat Action Plans (HAPs)80 monitoring 242 indicator species10 habitat mapping, aerial photography external impacts12 6–7 aquatic invertebrate367s 170, 182 , 186 grazing 126–7 lichens 284 habitat mapping, Phase16 5–I 6, 179, monitoring 238– 9 macroinvertebrates 137–8 245 habitat condition assessment126 TWINSPAN 136–7 aerial photography18 2, 186 management requirements12 6–7 inferences 23 analysis 183 monitoring 126–8, 127 information, conversion from data bias 179 quality attributes127 155 dominant species182 reclamation pressure126 infrared light beams439 expertise 179, 181 survey 126–8 insects field methods181 –2 undergrazing 238 abundance 355, 356 field season182 vegetation 126 flying 354, 355 fixed-point photography182 damage 128 malaise traps35 5–6 methods 179 Hedgehogs 455 window traps354 , 354–5 planning applications244 hedgerow(s) 118–19, 247 international conservation precision 179 extent 118–19 agreements 473–7 scale 182 ground flora11 8, 119 International Union for the survey preparation182 monitoring 118–19, 120 Conservation of Naturesee IUCN target notes182 quality attributes120 Red Lists time efficiency180 –1 species 118 Invertebrate Site Register 357 Habitats Directive (EU)15, 76–7 , 245, identification 121 invertebrates, aquatic 473–7 , 551 structure 118, 120 abundance 362 aquatic invertebrate366s survey technique119s artificial substrates 364–5 bats 446–7 trimming 118 , 120 attributes for assessing condition birds 427 Hedgerow Evaluation and Grading 359–60 bryophytes 293 System (HEGS)119 biotic scores for water quality 362 butterflies 333 Hedgerow Regulations247 collection techniques 365–6 fish 385 herbaceous communities community Freshwater Pearl Mussel365 condition composition 359–60, 366 fungi 277 assessment 121–2 structure changes 362 564 INDEX

invertebrates, aquatic (cont.) population lichens 279 conservation range 342 attributes for assessing condition evaluation criteria 365–7 size 342 279–80 status 366 presence–absence 342, 348 Biodiversity Action Plans 286 cylinder sampling 364 protected species 343 colony data analysis and interpretation protection status in EU and UK 357 numbers 280 362, 363, 364, 365 quadrats 349–50 size 280 field methods 360–2, 363–4, 365 site designation criteria 358 conservation geographical restrictedness species of conservation interest categories 286 366–7 343–4 evaluation criteria 284–5 habitat status indicators 367 specimen collection 348, 349 status in UK 286 identification 362 suction sampling 353–4 data analysis and interpretation kick sampling 363–4 surveys 341–2 280–2, 283, 284 monitoring 359, 361 methods 342–57 Eastern Scotland Index of population sweep netting 353 Ecological Continuity 285 density 360, 364 timed counts 348–9 ecological parameters 285 size 360 trap abundance 342 environmental change sensitivity presence–absence 360, 362 walkover of site 342–3 279 safety during surveys 359 window traps 354–5 ephemeral 285 species see also named groups Eu-Oceanic calcifuge Woodland diversity index 359 Island Biogeograph Theory 85 Index of Ecological Continuity of particular conservation IUCN Red Lists 68, 73–5 285 importance 365 bats 447–8 field methods 280, 282–3 surveys 359 categories 73–5, 74 fixed-point photography 283–4 equipment 364 guidelines for national lists 79 grazing 280 methods 360–5, 361 terrestrial invertebrates 358 growth rate 285 timing 359 habitat 284, 285 sweep netting 363 JOLLY program 269–70 antiquity and health 284 vegetation sampling 360–2 Jolly–Seber analysis 269–70 condition 280, 280–2 water quality 362, 367 judgement sampling 29–30 susceptibility to change 282 invertebrates, terrestrial identification 279, 490 abundance 342, 355 Key Reptile Sites 411 indicator species 284 adult feeding and resting site kick nets 363 International Responsibility searches 344–8 kick sampling, aquatic invertebrates category 286 artificial refugia 356–7 363–4 localised habitats 279 attributes for assessing condition Kruskall–Wallis test 455–6, 458, monitoring 342 554 frequency 283 conservation methods 280–4, 281 evaluation criteria 357–8 Land Classification System (ITE) 171 New Index of Ecological Continuity status in UK 357–8 Land Cover Map (UK, 1990) 161–2, 284–5 count timing 349 171 pH assessment 282 data analysis and interpretation Land Cover of Scotland (1988) 169 pollution 280 348, 349, 350, 352–4, 355, land management protection in EU and UK 285–6 356, 357 grazing 239 quadrats 282–3 destructive sampling 348 impact surveys on upland habitats rarity 286, 287 distribution atlases 357 239–40 Red Data List 286 distribution map 344–8 land reclamation, saltmarsh habitat sensitivity to change 284 diversity 344 152 site designation criteria 286–7 field methods 344–8, 348–9, 350–2, Landsat satellites 156 species of conservation importance 353, 354–7 laser range-finders 263, 495–6 279 flying insects 354 latrines substrate pH 280 grids 344–8 Badgers 466 transplanting 279 habitat features 343 Water Vole 464, 464–5 trees 284 identification 341–2, 348, 349 LCM2000 Classes 163–4 Western Ireland Index of larval feeding and resting site licences Ecological Continuity 285 searches 344–8 bat surveys 441, 442 Western Scotland Index of malaise traps 355–6 mammals Ecological Continuity 285 micro-habitats 344 marking 463 LIDAR (light detection and ranging monitoring 341–2, 345 trapping 461–2 instrument) 158 indirect 344 Otter surveys 465 light traps, macromoths 335, 336, 338 niche specialisation 344 reptile surveys 404 limestone pavement pitfall traps 350–3, 351 requirements 46 external impacts 125 Index 565

habitat condition assessment evaluation criteria 301–2 presence–absence 455, 458 124–5 status 302 Otters 465 management requirements125 field methods298 , 299–300 protection status in EU/UK 469–71 microclimates 124 grapnel surveys199 quadrats 458 monitoring 124–6, 125 field methods20 0–1 faecal pellet counts 456–7 physical structure124 time efficiency199 tracks 459 quality attribute125s timing 201 radio tracking 463 species lists124 mean trophic rank (MTR) system Otters 465 surveys 124–6 138 road kills 465 liming 123 monitoring 295–6, 297 site designation criteria 471 liverworts see bryophytes population size296 species of particular conservation lizards presence–absence 296 importance 464–9 Common 408, 409 protection status in EU and30 2 UK spotlight searches 460–1 cloaca markings 409–10 quadrats 296–9 surveys 450 conservation status41 0 rivers 136– 7, 138–9 direct methods 460–4 handling 409 site designation criteria302 indirect methods 455–60 Sand 404, 408 species of conservation importance survival 450 conservation status41 0 300–1 territory Local Nature Reserves94 standing open water133 –4, 136 boundaries 458–9 lochs, freshwater132 surveying 295–6, 297 size 458–9 log-normal distribution61 –2 transects 296 –9 tracks 459 lone working procedures4 7 water or substrate sampling transects 458, 460–1 Longworth trap461 299–300 faecal pellet counts 456–7 look–see method for vascular plantMAGICs project (Multi-Agency tracks 459 307–12 Geographical Information for trapping 450, 461–2 field methods 307 the Countryside)249 mark–recapture 462–3 population estimates307 malaise traps355 –6 trapping web 463 trend detection312 mammal ladders397 see also named groups mammals Man and the Biosphere Programme McNemar’s test58 , 554 abundance index46 4 473–7 macroinvertebrates, indicators attributes for assessing condition management 137–8 450 burning 240 macromoths bait marking45 8–9 monitoring 237 attributes for assessing condition breeding site counts455 planning and site evaluation 95–6 335 breeding success or condition450 Mann–Whitney test 56, 554 colony number33 5 burrows 455 maps/mapping 19 conservation conservation aerial photography 167, 171 evaluation criteria 339–40 evaluation criteria46 9–71 bait marking for mammals 459 status in UK34 0 status in 47UK1 bird territories 415–16, 418 egg counts33 9 density estimate 455, 459 demographic techniques for field methods336 , 338–9 direct observation45 0 vascular plants 316, 317 larval counts33 9 faecal pellet counts45 6–7 digitisation 183 light traps 335, 336, 338 Otter spraint46 5 fixed-point photography 178 monitoring 335, 337 feeding signs45 8 Ordnance Survey 181 pheromone traps33 5, 336–9 hair tubes or catchers459 –60 base 168 population handling 462 scale 182 range 335 licences Otters 465 size 335 marking 463 overlay procedures 172–3 structure 335–6 Otter surveys465 relocation of permanent plots 495 protection status in EU and UK trapping 461–2 rivers 139 339–40 marking methods46 2–3 scale in NVC surveys 190, 191 site designation criteria340 mark–recapture 462–3 systematic total counts of vascular surveys 335, 337 mortality 450 plants 312 methods 336–9 data methods463– 4, 465 terrestrial invertebrates 344–8 transects 335, 339 nest boxes 455, 466–7 see alsostock maps macromycetes 271 nests 455 Margaritifera margaritifera (Freshwater macrophytes, aquatic point counts 460–1 Pearl Mussel) 365 alien invasive species302 population index 462 maritime habitat attributes for assessing condition population size 450, 455–6, 463, boulders/rocks 145–7 296 464 MARK program 269–70 community composition 296 faecal pellet counts 457 markers conservation mark–recapture techniques 462 buried metal 495 566 INDEX

markers (cont.) financial resource16s National Countryside Monitoring posts for relocation of permanentfrequency 15–16 Scheme (NCMS) 168 plots 495 health and safety issues46, 4 7–8 National Nature Reserves 93 potential toxicity282 licence requirements46 National Parks and Access to the mark–recapture techniques26 8–70 long-term resource availability Countryside Act (1949) 93 amphibians 399–401 42– 5 National Vegetation Classification birds 413, 418 management objectives16 (NVC) 11, 113, 245 fish 375, 378 , 379, 381 measurement error2 1–3 associated species 184 mammals 462–3 measurements 19–20 boundaries 187 models 269, 270 methods communities 184, 187 principles 268–9 repeatability 42 computer programs for vegetation reptiles 404, 408–10 selection for attribut1e7s– 23 analysis 190, 192 marsh 128–30 testing 25–7 Notified Features 184 MATCH program19 0, 192, 193 multi-level sampling3 4–5 preferential species 184 meadows, conservation importance objectives 3 –5 Red Data Book 247 250 for features of interest8–15 repeat mapping 186 mean (statistical)2 6– 7, 51, 554 setting 6 –17 sample location 30 estimating 53 precision 25–7 structural changes 186 mean trophic rank (MTR) system138 preliminary field trials25– 7 subcommunities 184, 187 measurement 19–20 preparation checklist8 quadrats 189 accuracy for distance sampling protocol 40–2 surveys 186 260, 261 random sampling3 0–1, 35 change monitoring 193 errors 21, 21– 3 range of conditions20– 1 communities 190 precision 25–7 reporting 16, 40 error estimates 186, 191 median (statistical)2 6, 554 review 42–6 field methods 188 medical issues in fieldwork47 sample locations2 9–34 map scale 190, 191 meres 132 by judgement2 9–30 mosaics 189, 189–90, 191 mesotopes, blanket bog144 permanent 27–9 procedure 189 metapopulations 14, 14–15 sampling 19 quadrat 187, 189 microalgae 299–300, 302 strategy design2 3–5 repeatability 186 micro-habitats 15 staff resources4 5–6 site appraisal 187 microtagging 379 stratified sampling3 1–4 stratified sampling 187 microtopes, blanket bog144 optimal allocation34 time efficiency 187 mini-quadrats 208 systematic unaligned35 time required 186 abundance 211 subdivision into units17 timing 189, 190–90 field methods209 –11 time required 45 variability 191 random location210 –11 montane habitats vegetation boundaries 189–90, shoot frequency20 9–10 acidification 141–2 191 sub-plot frequency211 air pollution 141–2 vegetation condition 184 time efficiency208 monitoring 141–3, 142 Natterjack Toad Site Register 401 mist netting417 –18 quality attributes 142 Natura 200 network 77 mode (statistical)2 6–, 554 surveying 141–3 Special Areas of Conservation 90 moisture meters, soil197 vegetation 141–3 Natural Heritage Zones (SNH) 171 Monel tags463 mortality 13–14 Nature Conservation and Amenity Monitoring Agriculture by Remote data methods for mammals 463–4 Lands (Northern Ireland) Order Sensing (MARS)161 moss see bryophytes (1985) 469 monitoring/monitoring programmes moths see macromoths Nature Conservation Review criteria 3 –5, 7 , 551 Mouse 86, 87 adaptive sampling36 Harvest 468 nature reserves 94 attributes 18 Wood 458 Near Threatened category 74 baseline surveys1 6–17 see alsoDormouse nearest individual methods 233 bias 21–3 multi-level sampling 34–5 nearest neighbour methods 456, cluster sampling3 4–5 multivariate analysis 62 456–7 common standards in 5 UK Mussel, Freshwater Pearl 365 nest boxes, mammals 455, 466–7 consistency 40–2 Dormouse 466–7, 468 see alsobat environmental damage potential Najas flexilis (Slender Naiad) 301 boxes 19 National Bat Monitoring Programme nests, mammals 455 equipment requirements46 438, 441 Red Squirrel 468–9 external factors16 methodology 443 netting features of conservation interest National Biodiversity Network 357 amphibians 394–5 6–8 Species Dictionary Project (JNCC) mist 417–18 objectives 8–15 276 push, throw and lift 383 Index 567

New Index of Ecological Continuitydepth of layer196 preservative 351, 352 (NIEC) 284 –5 raised bog130 reptiles 408–9 newts peat soil erosion243 species mobility350 bottle traps39 2–4 permanent plots, burned areas242 terrestrial invertebrates35 0– 3 egg searche399s permanent plots, woodland224 –9 vegetation 350 Great Crested388 field methods22 5– 8 planimeter 168 belly pattern photography400 key elements228 planning applications, vegetation IUCN risk category402 plot shape22 5–6 impacts 244 protection status401 –2 pesticides 119–20 Planning Policy Guidance on site designation403 pH meters, soil195 –6 Nature Conservation (DEFRA) survey requirements391 pheromone traps, macromoths335 , 469–71 mark–recapture techniques 336–9 plant communities 394 photographs, photography173 aquatic assemblages139 metamorphs 393 bryophytes 291–2 grazing in upland habitats239 population decline403 burning monitoring241 loss with erosion243 Smooth 401, 402 centre pole system177 –8 National Vegetation Classification terrestrial searches398 film speed175 184, 187 torch counts388 , 392 field methods17 5–8 , 276 regeneration sites238 night surveys, Hares469 fungi 275, 275– 6 species richness23 8–9 Nightjar 420 fixed-angle 174, 176– 7 see alsoherbaceous communities night-sights 419–20 fixed-point 174 Plantlife 318 nocturnal surveys, birds419 –20 lichens 283– 4 conservation programmes 318 nominal data2 0, 51 Phase I habitat mapping182 PlantLife International 83 non-parametric tests4 1, 554 quadrats in fungi surveying275 plotless sampling, woodland 232–4 normal distribution3 7–8 time efficiency174 field methods 233–4 normal probability plots52, 61 vascular plants317 time efficiency 232 null hypothesis4 1, 41, 43, 554 woodland permanent plots plots, relocation of permanent nutrient status 224– 5 495–6 fen habitat129 frequency 176 point counts 256, 266–7 rivers 137 Great Crested Newt belly pattern birds 417 standing open water132 , 132–3 400 fixed-radius or infinite-distance nutrients lichens 283 266–7 cycling with dunging238 limestone pavement126 Hares 469 soil 109 quadrats for lichens283 mammals 460–1 relocation of permanent plots495 principles 266 observer bias2 1–2 remote sensing155 point-centred quadrat method 233 Odonata see dragonflies and resolution trade-offs15 6–8 Poisson distribution 61, 62 damselflies reptile markings40 9– 10 pollution oil pollution river habitat survey198 lichens 280 saltmarsh habitat152 seasons 176 nitrogen-based alkaline 284 sand dunes150 timing 176 rivers 139–41 open spaces, woodland habitat trees 227 saltmarsh habitat 152 113–14 vascular plants31 7–18 sand dunes 150 ordinal data2 0, 51 data analysis and interpretation sea cliffs 146 Otter, European465 317– 18 soil changes 109 otter trawl382 woodland habitat11 1, 114 standing open water 135 overgrazing 238 see alsoaerial photography; see alsoair pollution Owl, Barn420 cameras and camera systems ponds 132 phytoplankton surveys299 pondweed identification 302 palatability of plants238 PIT (passive integrated transponder)pools, temporary 132 Panjet tattoo gun400 tags 400–1, 409, 463 population(s) 23, 554 parametric tests4 1, 54–5 , 61, 554 pitfall traps age 14 data transformation61 amphibians 395–8, 396 biogeographical 70 parkland capture rates350 conservation status 70 external impacts115 drainage 351 , 397 density for Otters 465 management requirements115 emptying 351–2 dynamics 13–14 monitoring 114–17 fences 395, 395–7 , 396 estimates 24 regeneration 115 reptiles 408–9 fish 384 shape/size 115 mammal ladders397 estimation stands 115 mark–recapture techniques397 mark–recapture techniques 268 peat population size indices350 , 397 removal methods 268 blanket bog143 predation risk397 trapping webs 267 568 INDEX

population(s) (cont.) representativeness 85–6 terrestrial invertebrates 349–50 fragmentation 14–15 scoring systems8 6–8 timed searches 257 fungi 272 selection 81–8 vegetation importance 70–1 , 97–9 criteria 83–6 recording on eroded ground 244 index 20 size 84, 84–5 recovery following burning 242 mammals 462 target-led approache8s 1–2 woodland permanent plots 224 international importance71 threat value8 1–2 see alsomini-quadrats isolation 14–15 threshold criteria8 1–2 quantitative data 20, 51, 54 mean 26–7 minimum desirable13 quadrats 19, 25, 258–60 Rabbits minimum viable1 2–13 algae 296–9 , 300 burrows 455 risk of extincti7o0n– 1 analysis 259– 60 faecal counts 455 sink 14, 14– 15 aquatic macrophytes296 –9 transects 460 size 13, 27 bryophytes 291 radar source 14, 14– 15 butterfly egg or larval counts peat depth measurement 196 status attributes73 331–2 synthetic aperture 158 structure 14–15 conventional frame20 3, 208 radiation, reflection 155 total index258 uses 202–4 radio tracking 419 trend detection5 9–60 fixing 282 bats 445–6 population size frame 206 mammals 463, 465 amphibians 387 frequency Otters 465 bats 442 data 259 –60 Ramsar Convention 91–3, 473–7 birds 412 measures 258– 9, 493 aquatic invertebrates 366 fish 382 fungi surveying and monitoring birds 428 indices from pitfall traps 274–5 fish 385–6 350, 397 grazing monitoring23 8–9 waterfowl flyway populations 70, mammals 450, 455–6 , 463, 464 lichen surveys28 2–3 83 faecal pellet counts457 data recording28 2–3 Ramsar sites mark–recapture techniques mammals 458 designation 67, 83, 92 462 faecal pellet counts456 –7 selection criteria 92–3 Red Squirrels468 tracks 459 terrestrial invertebrates 358 reptiles 404, 409 nested for FIBS212 –12 random distribution 260 Population Viability Analysis (PVA)73 field methods21 4–16 random sampling 30, 30–1, 35 pot traps379 recording methods214 –15 randomisation tests 57 power analysis4 0, 43 species choice214 ranging pole 175, 178 presence–absence surveys257 time efficiency213 ranks, statistical methods 55–6 analysis 258 NVC surveys18 7, 189, 192–2 rarity Priority Habitats8 0, 248 permanent 29, 202–3, 209 , 259 forms 69 evaluation 248 algae and aquatic macrophytes global 68–70 priority setting, national71 298 importance 68–70 Priority Species80 fungi 275 lichens 286, 287 probability 43, 554 lichens 259 local 68–70 probability distribution3 7–8 , 554 potential damage to species259 protected areas 83 protected areas photographing of lichens283 value 81–2 abundant species83 point 217 spatial dimension 68–70 algorithms 82– 3 field methods218 Ratcliffe criteria 246, 250 complementarity 82–3 time efficiency217 reclamation criterion-based systems8 1–2 positioning 282 fens 129 designation of high conservation principles 258–9 heathland 126 priority species or habitats67 river habitat survey198 recruitment 13–14 diversity 83–4 sedentary species25 5, 259 Red Data Book 71, 73 ecological value8 1–2 size 205, 258–9, 494 aquatic invertebrates 366 European 76 bryophytes 291 aquatic macrophytes 302 evaluation criteria8 3–6 fungi surveying274 bryophytes 293–4 irreplaceability level82 lichen surveys282 butterflies 333 linkage to similar habitats85 terrestrial invertebrates dragonflies and damselflies 327 naturalness 85 349, 350 fungi 277, 278 Nature Conservation Review vegetation sampling 493–4 lichens 286, 287 criteria 86 statistical methods 260 macromoths 340 proximity to similar habitats85 temporary 202, 205, 259 NVC vegetation types 247 rare species83 algae and aquatic macrophytes terrestrial invertebrates 357–8 rarity value8 1–2 298 vascular plants 320, 321 Index 569

Red Lists resampling methods4 1, 56–7 stratification 153 European 76 reservoirs 132 vegetation 151–2 national 79 resistivity counters376 samples 23, 555 assessments 79 Revised Index of Ecological location 29–34, 34– 5 regional assessments79 Continuity (RIEC)284 permanence 27–9 see alsoIUCN Red Lists ringing, birds41 7–18 number 23–4 redd nets383 river(s) required 36–8 Redstart, Black42 1–2 abstraction 139–41 selection 30 reedbed habitat, monitoring and aquatic plant assemblages139 size 27, 28 surveying 128– 30 external impacts13 9–41 small 57, 61 refugia, artificial fisheries managemen141t unit choice52 grid pattern406 flood defences141 sampling location 407 habitat condition assessme1nt36 –9 adaptive 36 reptiles 406–7 hydrology 139 aerial photography171 terrestrial invertebrates356 –7 ma cr oi nv er te br ate13 7–i 8 nd iccluster at or 3 4–s5 timing 406 macrophytes 136–7, 138– 9 consistency 40–2 see alsoartifici al substrate407s management requirements13 9–41 judgement 29–30 regeneration mapping 139 locations 19 lowland wood-pastures115 monitoring 136–41, 140 major and minor units35 parkland 115 morphology 139, 197–201 methods 19 regression analysis5 9–60, 554–5 naturalness 85 multi-level 34–5 remote sensing nutrient status137 optimal allocation36 satellite-based 20, 156, 162 pollution 139–41 object 23 recommended uses162 quality attributes140 random 30, 30–1, 35 removal methods268 surveys 136–41, 198 strategy 32 representativeness, protected areas classification bands198 design 23–5 85–6 field methods199 stratified 31–3 , 33– 4 reptiles GPS use200 mean estimation53 abundance 407, 408, 408–9 pH measurement200 optimal allocation34 artificial refugia40 6–7 photography 198 random 171 attributes for assessing condition quadrats 198 standard deviation53 404 transects 198 systematic unaligned35 breeding success404 turbidity 200 two-level 36, 53 conservation types 136–7 unit 23, 25 evaluation criteria41 0–11 water chemistry137 see alsoplotless sampling, status in 41UK0 –11 water control structures141 woodland data analysis/interpretation40 7, see alsoSERCON (System for sand dunes 148–50 408, 408–9 Evaluating Rivers for erosion 150 density estimates407 CONservation) grazing 150 designated sites404 River Corridor Survey197 management 150 field methods406 –7, 407–8 , aquatic macrophytes298 monitoring 151 409–10 Environment Agency86 , 139 oil pollution 150 handling 409 River Habitat Assessment, aquatic quality attributes 151 identification by markings409 –10 macrophytes 298 stratification 150 Key Sites411 RIVPACS (River Invertebrate vegetation 149, 150 licences for surveys404 Prediction and Classification saplings, woodland habitat 112–13 marking 409– 10 System) 362, 367 Saproxylic Quality Index 358 mark–recapture techniques40 4, road kills465 satellites 408–9, 409–10 rock face erosion243 bird tracking 419 monitoring 404, 405 Romer dot grid179 , 183 commercial high-resolution 156 mortality 404 costs 158 pitfall traps40 8–9 salt deposition, sea cliffs146 earth-observing sensors 157 population size40 4, 409 saltmarsh habitat15 0–2 geostationary 156 class 411 coastal protection152 remote sensing systems 156 presence–absence 404 erosion 150–1 , 152 scanning instruments, airborne 158 protection status in UK/EU410 grazing 152 scatterplots 51 site designation criteria411 land reclamation152 scent stations 459 standard walk transects407 –8 monitoring 150–2 scoping surveys 245 surveys 404 oil pollution152 scoring systems methods 404–10, 405 organic litter deposition152 protected areas 86–8 survival 404 quality attributes152 weighting 88 trapping 408–9 sediments 150–1 Scottish Blanket Bog Inventory 165 570 INDEX

Scottish Cryptogamic Conservation structure 210 bats 447 Project 293 see alsomini-quad rats; quadrats206 boundary definition9 1 scrub habitat10 7–14 significance level41 bryophytes 293 clearance on sand dunes150 Simpson’s index84 grading 89–90 condition assessment10 7–14 site(s) information provision9 0–1 monitoring 107–14 conservation designation8s 8–95 monitoring 8 spread with undergrazi238ng EIA evaluation9s 6–101 selection criteria9 2 see alsowoodl and habitat evaluations 81– 8 Special Protection Areas (SPAs)76, 89 sea cliffs14 5– 7 management planning9 5–6 birds 427–8 burning 146 size 84–5 monitoring 8 erosion 146 Site Condition Monitoring (SCM)552 species monitoring 147 Sites of Community Importance abundance objectives1 3 pollution 146 (SCIs) 89 assemblages 6–7 quality attribute147s Sites of Special Scientific Interest attributes 12– 15, 67 salt deposition146 see SSSIs monitoring 9 vegetation 146, 146–7 skin staining, toads400 conservation seabird surveys at 419sea slopes 179 categories 73 searches, timed25 7–8 erosion 243 concern 79 sedentary species255 maritime 145 –7 high priority6 7 quadrats 259 Slow-worms 408, 409 priority lists7 2, 72–80 sedges, identification124 chin spots40 9–10 status 70 sediments, saltmarsh15 0–1 conservation status 410 density 11 seedlings 112 handling 409 differences 22 seine netting380 slugs, artificial refugia356 –7 distribution 423 seismology, peat depth measurementSMOLAC knowledge-based change diversity 83–4 196 detection system17 3 diversity index for aquatic selected colonies survey of vascularsnails, artificial refugia356 –7 invertebrates 359 plants 314–15 Snakes endemic, at high risk of extinction colony Grass 410 70– 1 population size315 Smooth 404, 410 frequency 11 range 315 soil genetic diversity1 5 selection 314, 314 –15 core samples196 globally threatened 70, 75 field methods314 –15 drainage 197 habitat requirements 15 representative colonie314s eutrophication 238 minimum desirable population 13 SERCON (System for Evaluating fertility 195 minimum viable population 12–13 Rivers for CONservation) field capacity19 7 monitoring 6, 7 –8 86, 139 forest 109 attributes 9 aquatic invertebrate367s free-draining water19 7 population sex ratio14 grazing in upland habitats239 dynamics 13–14 Shannon’s index84 heathland 126 size 13 Shearwater, Manx60 horizons 196 structure 14–15 Sherman trap461 indicator strips19 5–6 presence–absence 10–11 shingle above high 14tide7– 8 moisture 197 quantity 12–13 coastal defences148 nutrients 109 richness 84 hydrology 148 organic matter19 7 typical 10 monitoring 149 peat 243 abundance 10–12 quality attribute149s pH 195–6 Valuable Ecosystem Components vegetation 148 physical characteristics195 –7 67 shingle extraction148 plant-available water197 see alsoindicator species; mobile Shrew 459–60 plant-unavailable water19 7 species; sedentary species trapping 461–2 pollution 109 Species Action Plans (SAPs) 80, 101 shrub vegetation profile 196 Species of Community Interest 76–7 cover estimates203 temperature probes195 – 6 Species of Conservation Concern enumeration 111 texture 196 (SPECs) 76, 80, 429 frequency methods204 vegetation influence19 5 categories 71 height 210 see alsoerosio n109 Species Rarity Index (SRI) 367 individual total counts202 soil moisture meters197 SPOT satellites 156 field methods20 5–7 soil organism communit19ies5 spotlight searches, mammal 460–1 quadrat size205 sonar equipment for fish countingspraint surveys, Otter 465 sampling strategy205 376 springs, woodland 109–11 time efficiency204 Special Areas of Conservation (SACssquirrels) 455 overgrazing 238 76–7, 89–91 distinction of Red from Grey 468–9 Index 571

feeding signs 458 parametric tests 41, 54–5, 61, 554 parametric methods 54 Grey 459–60 data transformation 61 Thematic Mapper 161, 165 Red 455, 459–60, 468–9 ranks 55–6 theodolites 495–6 transects 460 resampling methods 41, 56–7 Threatened Plants Database 320 SSSIs 93–4 software 64 tiles, artificial refugia 356–7 amphibians 403 terms 552–5 timed searches 257–8 site selection scoring system 403 timed searches 258 toads bats 446, 448–9 trend detection 59–60 amphibian terrestrial searches 398 Biogenetic Reserves 89 two-tailed test 42 egg searches 399 birds 427–8, 432 stereoscopes 167, 167 Natterjack 388, 391 habitats 423 Stoats, trapping 461 conservation status 402 bryophytes 294 stock maps 222–4 population decline 403 butterfly site designation criteria forestry 114 protection status 401–2 334 woodland habitat 111, 112, 114, Site Register 401 citations 249 222 spawn strings 398 definition 93–4 field methods 223 night counts 391 dragonflies and damselflies, site time efficiency 222 pitfall traps 397 designation criteria 327 stocking density 119, 123 population peak 392 fish 386 stoneworts 301, 302 skin staining 400 fungi, site designation criteria 278 identification 302, 491 spawn strings 398, 399 grassland communities 121–2 strandline vegetation 148–50, 151 torch counts 392 herbaceous communities 121–2 stratified sampling 31–3, 33–4 torch counts 388–92 lichens 286 mean estimation 53 bats 444 macromoth site designation optimal allocation 34 Total Stations 495–6 criteria 340 standard deviation 53 tracking stations 459 mammals 471 systematic unaligned 35 tracks, mammals 459 monitoring 8, 94 streams trampling reptiles 411 external impacts 139–41 erosion 243 scoring 86–8 habitat condition assessment vegetation 238 selection 136–9 transects 35, 219 approach 84, 86–8 management requirements 139–41 algae 296–9 criteria 86, 94 monitoring 136–41 amphibian terrestrial searches 398 guidelines 94, 247 surveys 136–41 aquatic macrophytes 296–9 Special Protection Areas (SPAs) 89 woodland 109–11 bats 440, 442–4 terrestrial invertebrate site sub-communities, National belt 219–20, 221, 255, 256 designation criteria 358 Vegetation Classification 184, bryophytes 291 vascular plant site designation 187 butterflies 328 criteria 320–1 sub-plot frequency, mini-quadrats adult counts 332 Wildlife Sites relationship 94 211 egg or larval counts 331–2 staff resources, monitoring suction sampling distance sampling 260, 262–3 programmes 45–6 preservative 353 distance bands 262–3 stand, forest 111–12 terrestrial invertebrates 353–4 dragonflies and damselflies 325–6 seedlings 112 vegetation 353 feeding 468–9 standard deviation 26, 51, 555 Surber-type sampler 363 field methods 220–1 estimating 53 SURGE program 418 fish 377 standard error 26, 27, 555 surveillance 4, 552 counts 376 standard operating procedure (SOP) surveying 3–5, 552 fungus surveying 275–6 40–2 objectives 3–5 grazing monitoring 238–9 standing crop method 456, 456–7 swamp habitat 128–30 Hares 469 stands, lowland wood-pastures/ swarming counts, bats 440 infinite-width 265 parkland 115 sweep netting 353 line 265 statistics amphibians 395 line 31, 219, 220, 255, 256 Bayesian inference 59 aquatic invertebrates 363 birds 416–17 categorical data 57–9 synthetic aperture radar (SAR) 158 dead wood surveys 235–6 choice of test 41, 54 systematic sampling 30 distance sampling 260, 261, 262 data analysis 49 Hares 469 descriptive 26, 51 TABLECORN program 192 infinite-width 265 frequency 260 TABLEFIT program 190, 192, 193 mammals 460 infinite width line transects 265 temperature probes, soil 195–6 principles 264–5 mammal faecal pellet counts 457–8 temporal bias sources 22 line intercept 219, 220–1, 256 non-parametric tests 41, 554 temporary plots, woodland 229–32 macromoths 335, 339 one-tailed test 42 test statistic 41, 43, 52 mammals 458, 460–1 572 INDEX

transects (cont.) regeneration monitoring 230 biodiversity 97 faecal pellet counts456 –7 stock mapping 222–4 categories 97 tracks 459 stump regrowth 113 ecological value definition 98 permanent 220, 221 see alsocanopy ; forest; woodland evaluation 100 algae and aquatic macrophytesT-square sample method 234 identification 67–8 298 t-tests 54–5, 555 value 101 permanent woodland plots226 turbidity recording 200 vascular plants 319, 321 Red Deer damage230 TWINSPAN program 136–7, 192, 193, variable circular plots (VCPs) 266 point 256 362 variance 26, 62, 555 count time263 typicalness see representativeness vascular plants distance sampling26 0, 261, 263 aerial shoot number 306 point counts266 undergrazing 238 attributes for assessing condition point intercept21 9, 220 –1, 256 United Kingdom 305–7 principles 266 amphibians conservation Red Squirrel surveys468 conservation status 402–3 evaluation criteria 318–21 river habitat survey198 protection status 401–2 programmes 318–19 seabird surveys at 419sea aquatic macrophytes status in UK 320 standard walk for reptiles407– 8 conservation status 302 demographic techniques 307, strip 256, 265–6 protection status 302 315–17 analysis 265–6 bats evaluation 321 principles 264 –5 conservation status 447–8 field methods 314–15, 317 temporary 220 protection status 446–7 flowering 303–4 algae and aquatic macrophytes bird protection status 427–32 grids 312–13 298 bryophytes growth 305–6 types 256 conservation status 293–4 identification 491–2 trapping webs267 protection status 293 IUCN criteria 320 amphibians 395 butterfly protection status 333 location markers 312 mammals 463 conservation status 246–50 look–see method 307–12 traps and trapping dragonflies marking 316, 317 baiting 461–2 conservation status 327 monitoring 303–5, 308 birds 417–18 protection status 327 frequency 304–5 bottle traps39 2–4 , 393 fish method selection according to checking 462 conservation status 386 growth pattern 303 fish 369, 378 –80, 379 protection status 385–6 photography 317–18 location 462 fungi population mammals 450, 461–2 conservation status 278 definition 303 mark–recapture 462–3 protection status 277–8 dynamics 306–7 mark–recapture techniques habitat protection status 245–6 size 304, 305, 314 268–70, 462–3 internationally important plant structure 306–7 Red Squirrel469 assemblages 318 viability 319 removal methods268 lichen protection 285–6 presence–absence 305 reptiles 408–9 macromoths protection status in EU and UK trawl netting38 1–2 conservation status 340 319–20 trees protection status 339–40 reproduction 305–6 age 223 mammals selected colonies 314–15 condition 228 conservation status 471 site designation criteria 320–1 cover estimation227 protection status 469–71 size 305–6 crown size226 reptiles surveys 303–5, 308 dead wood surveying and conservation status 410–11 systematic total counts 312–14 monitoring 234–6 protection status 410 Threatened Plants Database 320 density estimation233 –4 terrestrial invertebrates Valuable Ecosystem Components diameter 227 conservation status 357–8 319, 321 girth 227 protection status 357 vegetation growth form223 vascular plant protection status aquatic 197–201 health 227 319–20 assessment of types 250 height 226 –7 see alsoBiodiver sity Action Plan (UKblanket bog 143–4 parkland 115 BAP) burning 242 permanent plots224 –9 upland habitats, land management community mosaics 12 photographs 227 impact surveys 239–40 cover estimates 203 recording of individuals228 development impacts 244 Red Deer damage 230 Valuable Ecosystem Components ditches 117 regenerants 228 (VECs) 65–8, 96, 245, 246 field monitoring 121 Index 573

floristic component survey time Water Framework Directive85 mammals 455, 469 385–6 water or substrate sampling, algae Red Squirrels46 8 grazing in upland habitats239 and aquatic macrophytes reptiles 410– ground in woodla10nd8 , 113 299–300 Wildlife Sites 94–5 change 113 water table approaches 95 recording 114 blanket bog14 3 criteria 95, 95 seedlings 112 raised bog 130 purpose 94–5 heathland 126 woodland 109–11 window traps354–5 damage 128 waterbirds, migratory 419, 427 , 428 woodland habitat 107–14 height 238 –9 waterfowl flyway populatio7n0 s age 223 montane habitats14 1, 141 –3 Weasels, trapping46 1 baseline recording114 quadrat size49 3–4 weather boundaries 223 recording on eroded ground244 bias source2 2 delimitation 109, 114 saltmarsh habitat15 1–2 erosion 243 change 108, 111–12, 114 sampling for aquatic invertebrates fixed-point photography17 9 condition assessment10 7–14 360–2 pitfall traps 350 dead wood surveying and sand dunes149 , 150 window traps35 4 monitoring 112, 234–6 sea cliffs14 6, 146–7 Weil’s disease45 7 environmental conditions 107 shingle above high 148tide Western Ireland Index of Ecological external impacts 114 soil influence195 Continuity (WIIEC) 285 forest operations 109 spectral signatur155e Western Scotland Index of Ecological hydrology 109–11 standing open water132 , 134 Continuity (WSIEC)28 5 managed semi-natural 112 strandline 148–50 Wetland Bird Survey (WeBS)412, 413 management requirements 114 suction sampling35 3 wetlands monitoring 107–14, 110 trampling 238 aquatic invertebrate36s 6 compartmentalisation 114 wetlands 128 birds 427, 428 condition of wood 114 see alsoground vegetationname; d fish 385–6 strategies 108 vegetation types35 4 monitoring 128–30, 129 open spaces 113–14 VESPAN program19 0, 192 naturalness 85 permanent plots 224–9 video recording, bats43 9 quality attributes 129 photographs 111, 114 Vole 459–60 surveys 128–30 plotless sampling 232–4 Bank 458 vegetation 128 point transects 261 Water 458, 464 see alsoRamsar Convention; quality attributes 110 Vulnerable category7 4 Ramsar sites regeneration 108–9, 112–13 Wilcoxon’s signed rank 5test6, 555 regrowth from stumps 113 walls, farmland11 7–19 Wildlife & Countryside Act (1981, UK)Revised Index of Ecological Warbler, Dartford42 2 77–8, 93, 245 Continuity 284 water alien invasive species302 saplings 112–13 clarity 134 amphibians 401, 402 seedlings 112 control structures for rivers141 aquatic invertebrate36s 6 shape 109 quality bats 446–447 size 109 aquatic invertebrates36 7 birds 427–8, 429 soil 109 biotic scores36 2 bryophytes 293 stand 111–12 water, standing open butterflies 333 structure 223 clarity 134 dragonfly protection status327 stock maps and mapping 111, 112, dystrophic 132–3 fish 386 114, 222–4 eutrophication 135–6 Freshwater Pearl Mussel365 structure 107–8 external impacts13 5–6 fungus list277 –8 temporary plots 232 habitat condition assessment lichens 286, 287 see alsocanopy ; trees; vegetation, 132–5 macromoths 339 ground in woodland macrophytes 133–4, 136 mammals 455, 469 Woodlark 421 management requirements13 5–6 protection 466 wood-pastures, lowland monitoring 132–6, 135 Red Squirrels46 8 external impacts 115 nutrient status13 2–3 reptiles 410 management requirements 115 water 132 terrestrial invertebrates357 monitoring 114–17, 116 oligotrophic 133 vascular plants320 quality attributes 116 plant communities13 2 Wildlife & Countryside Amendment regeneration 115 quality attribute13s 5 Act (1985, UK)93 shape and size 115 surveys 132–6 Wildlife (Northern Ireland) Order stands 115 trophic categories 132 (1985) 401 World Heritage Convention (1972) vegetation 132, 134 Badgers 465 473–7 water chemistry13 3–4 bats 447 World Heritage Sites 88