Review of hill-edge habitats in the uplands of England and Wales. BD1235
Milsom, T.P., Aegerter, J., Bishop, J.D., Allcock, J.A; Barker, D., Boatman, N.D., Hill, V., Jones, N., Marshall, J., McKay, H.V., Moore, N.P., & Robertson, P.A.
Central Science Laboratory, Department for Environment, Food & Rural Affairs, Sand Hutton, YORK, YO41 1LZ.
August 2002 Reformatted (with corrections) January 2003
© Crown Copyright CONTENTS Acknowledgements iii Executive summary iv Introduction to the hill-edge and Tim Milsom 1 scope of review Origins and dynamics of hill-edge Tim Milsom, Diane Barker, 5 James Aegerter & John Allcock Hill-edge – location and extent James Aegerter & John Allcock 17 Vegetation Naomi Jones & Nigel Boatman 70 Invertebrates Helen McKay 111 Amphibians & reptiles Diane Barker 121 Birds Tim Milsom 127 Mammals Niall Moore 168 Resume and identification of gaps in Tim Milsom & Peter Robertson 171 current knowledge and future research needs Annotated bibliography Julie Bishop & Val Hill 176 Appendices 1. Hill-edge – location and extent: James Aegerter 226 sensitivity analysis 2. Plant species list Naomi Jones & Julie Bishop 237 3. Common land surveys relating to Naomi Jones & Jo Marshall 243 hill-edge
ii ACKNOWLEDGEMENTS
This project was commissioned by the Conservation Management Division of Defra.
We are very grateful to the staff of the Regional Development Service of Defra (Defra RDS), Countryside Council for Wales (CCW), English Nature (EN), the North York Moors, Yorkshire Dales, Peak District and Dartmoor National Park Authorities, RSPB, National Trust and the Game Conservancy Trust for participating in the consultation exercise.
Particular thanks are due to Steve Peel (Defra, RDS) for identifying contacts and organising meetings with Defra staff; to Niall Watson and Claire Millar (Defra, RDS) for detailed discussions about remote sensing information on the hill-edge and for GIS material; to Murray Grant (RSPB) for organising a meeting with national specialists from the RSPB and for arranging access to unpublished RSPB reports, with the assistance of Mark O’Brien and the library staff at the RSPB library at Sandy; to Barbara Jones (CCW) for organising the consultation meeting at Bangor and for follow-up information; to Rod Starbuck (Defra, North Peak ESA Project Officer) for organising the meeting with local specialists from the Peak District and for much useful information; to Steve Trotter (National Trust) for hosting the Peak District meeting; to David Glaves (Defra, RDS) for organising the meeting with specialists from Dartmoor; to Peter Barfoot (North York Moors National Park) for organising several meetings with his staff; to Tim Thom (Yorkshire Dales National Park) for a very impressive discourse on hill-edge issues in the Yorkshire Dales and, finally, to Simon Bates (EN, Dartmoor) for lending us his Master’s thesis on the ffridd of North Wales.
We are very grateful to Jo Judge (CSL) for assistance with the GIS analyses, and to Linda Crossley (CSL) for preparing the final report in PDF format.
iii EXECUTIVE SUMMARY
x The hill-edge is the zone of transition between the upper margins of improved farmland in the uplands and unenclosed moorland. x This review was undertaken because of concerns about recent habitat changes, especially agricultural improvement, and their adverse effects on the plant and animal communities of the hill-edge, and because the hill-edge has been largely overlooked in the extensive literature on the uplands in Britain. x The principal objectives were as follows: (i) to characterise hill-edge habitats and to assess what is known about their species assemblages, physical characteristics and management features, (ii) to review the causes and extent of change in these features over recent decades and their impact on biodiversity and (iii) to identify gaps in current knowledge and recommend potential management options to enhance or restore the biodiversity value of these habitats. x The objectives were addressed by a literature review, consultation exercise and a GIS analysis of mapped data. x The chief characteristic of the hill-edge is the mosaic of habitats that includes inter alia unenclosed rough grazing, enclosed grazing land that has been abandoned, bracken beds, wet flushes around spring heads, scrub, relict woodland, patches of dwarf shrub heath and grass moorland, and isolated improved pastures or hay meadows. x The mosaic is the product of changes in land use, particularly episodes of agricultural improvement followed by abandonment. x Historical surveys of changes in land use in seven upland national parks in England and Wales showed that the conversion of rough pasture (moorland & rough grazing) to improved farmland and the reversion of improved land to rough pasture had occurred repeatedly throughout the 19th and 20th centuries. However, the rate of conversion to improved farmland increased in several, but not all, national parks after 1950. x Afforestation with conifers was extensive after 1920 in four national parks where it is likely that substantial areas of hill-edge habitat were eliminated as a result. x A probabilistic method entailing the application of GIS methods to mapped data from the CEH Land Cover Survey 2000 was employed to model the extent and habitat composition of the hill-edge in England Wales. x The combined estimate from the major upland regions of England and Wales was 680,175 ha. Separate estimates of the area of the hill-edge are produced for each of 12 upland regions in England and Wales. The areas varied from 5,812 ha in the Shropshire Hill ESA to 148,425 ha in the North Pennines. The area of hill-edge in each region was compared with that of the core moorland. The median percentage of the core moorland area was 87% but the values varied from 31% in the North York Moors to 203% in the Lake District. x Details of the areas of each of the constituent habitats and a map are also presented for each upland area. The maps show the extent of moorland (ericaceous and grass), hill-edge habitats and conifer plantations. x A sensitivity analysis was undertaken to evaluate the effects of adjusting the model settings on the area estimates. The goodness-of-fit of the model was not
iv formally tested because there were no independent datasets that described hill- edge habitats and which were contemporary with the satellite images used in the compilation of the LCM2000 map. However, the predicted extent of hill- edge in areas known to the authors was considered to be generally good in most though not all areas. The proportion of land in the Lake District that had been assigned to the hill-edge was higher than expected. x The literature on plant and animal communities of the hill-edge was reviewed. Separate reviews were undertaken for vegetation, invertebrates, amphibians and reptiles, birds, and mammals. x The plant communities of the hill-edge have not been studied intensively and most current knowledge of the vegetation stems from Phase 1 habitat surveys and similar assessments. x Rough and semi-natural grasslands were the most widespread habitats on the hill-edge in England and Wales. Most grassland was acidic but significant areas of calcareous grassland were recorded from the North Pennines, Bowland and the Shropshire Hills. Neutral grasslands were particularly important in the North Pennines, Bowland and Northumbria. Dwarf shrub heaths comprised a very minor component of the hill-edge nationally. x Broad-leaved and mixed woodlands comprised 5-10% of the hill-edge in England and Wales but cover varied regionally and was high (>20%) in Dartmoor, Exmoor and the North York Moors. x Scrub generally occurred in small and scattered fragments, many of which are not regenerating. Juniper Juniperus communis ssp. communis scrub has a particular conservation value, and important stands occur in the north Pennines. x Less than 5% of the hill-edge in England and Wales was covered by dense stands of bracken Pteridium aquilinum. Bracken has increased over the past few decades, and probably continues to do so in spite of efforts to control it. x Grazing is necessary to maintain many semi-natural habitats. However, heavy grazing is generally detrimental and can lead to the replacement of habitat mosaics with homogeneous vegetation. Intensive grazing is probably the most important factor in the decline of Juniperus. The replacement of cattle by sheep in recent decades, coupled with high sheep stocking densities, has led to a deterioration in the quality of vegetation with an increase in Nardus, Molinia and Juncus at the expense of more palatable grasses and dwarf shrubs. x Agricultural improvement by reseeding, drainage, burning, cutting, fertilising, liming and herbicide use has resulted in a loss of species and habitat diversity. However, improved grassland will revert back to vegetation more typical of rough grazing. The rate of reversion depends on management, particularly drainage. x Afforestation has had a major impact on the vegetation of hill-edge habitats. Few plant species survive under mature conifers. In the late 1990s, conifer plantations covered between 5-10% of the hill-edge in England and Wales. However, the percentage cover varied between regions and was high (>29%) in Northumberland and North York Moors National Parks, and in the Cambrian Mountains ESA. x Studies from a small number of localities suggest that the hill-edge supports diverse species assemblages of invertebrates that may be dependent on the mosaics of habitats, which are characteristic of the hill-edge.
v x Within habitats, invertebrates perform important ecosystem functions, especially decomposition of plant material. Some groups are also important in food webs, especially as prey for birds. x Components of agricultural improvement (drainage, ploughing, reseeding and the use of pesticides) have been shown to be detrimental to some invertebrate taxa. Priority invertebrate species are included in the Biodiversity Action Plans for upland habitats. Some of these species, including the high brown fritillary Argynnis adippe, which is endangered, exhibit dependence on hill-edge habitats. x More is known about birds on the hill-edge than any other animal taxon. Distinctive assemblages of breeding species were identified from the hill-edge in the Pennines, Mid-Wales and Dartmoor; their composition varied between regions. Waders were the dominant group in the northern Pennines but comprised a relatively minor component of species assemblages on the hill- edge in Wales and SW England. Passerines of scrub and woodland margins were the characteristic species on the ffridd and on Dartmoor x Different species exploited hill-edge habitats in different ways. Two species were largely restricted to the hill-edge: black grouse Tetrao tetrix and red kite Milvus milvus (in central Wales only). Seven moorland species – golden plover Pluvialis apricaria, curlew Numenius arquata, ring ouzel Turdus torquatus, twite Acanthis flavirostris, merlin Falco columbarius, golden eagle Aquila chrysaetos and hen harrier Circus cyaneus - exhibited some dependence on hill-edge habitats. x The hill-edge supports 13 species that are covered by the EU Birds Directive (Annex I) and/or which are included on the List of Species of Conservation Concern. Black grouse and red kite are hill-edge specialists, while a further seven species nest on moorland but exhibit a degree of dependence on hill- edge habitats. The capacity of the hill-edge to support these species is of national or international concern. In addition, breeding waders occur in nationally important numbers on hill-edge habitats in the Forest of Bowland and the Yorkshire Dales National Park. x The population status of most hill-edge bird species is unfavourable. Most species are declining in most regions of upland England and Wales. The causes of the population declines have not been firmly identified in most cases but it is likely that agricultural improvement and afforestation have been contributory factors. x No amphibian, reptile or mammal species occurs exclusively on the hill-edge. However, two mammals, the barbastelle bat Barbastella barbastellus and water vole Arvicola terrestris, showed strong associations with hill-edge habitats in some regions of Britain. This association may be significant nationally because both species have an unfavourable population status and are the subject of UK Biodiversity Action Plans. x In principle, the Environmentally Sensitive Area and Countryside Stewardship Schemes provide the means to manage the hill-edge for biodiversity and landscape objectives. There is a need to develop conservation management prescriptions which reduce grazing pressure on hill-edge habitats and which maintain, or promote the development of, habitat mosaics. x Field experiments are required to determine the optimal patterns of grazing, including seasonal and longer-term patterns of use, together with sward
vi management, and to develop prescriptions for habitat restoration, e.g. increasing wetness in fields that have been drained. x Several strategic issues were identified. Seven moorland bird species of conservation concern nest on moorland but exhibit some dependence on hill- edge habitats. As this issue has implications for the designation of Special Protection Areas, the extent of this dependence needs to be determined. The breeding populations of several bird species, which are in decline in the lowlands, and are now concentrated in hill-edge habitats. The demographic status of these remnant hill-edge populations is not known and needs to be determined. The third issue relates to bracken. This species is a pest but mosaics of bracken and other vegetation appear to be an important habitat for some invertebrates and birds in some areas. These habitat associations, and the factors that determine them, need to be examined further to develop an appropriate local management strategies
vii INTRODUCTION TO HILL-EDGE AND SCOPE OF REVIEW
Background
The hill-edge is the zone of transition between the upper margins of farmland in the uplands and unenclosed moorland above. The term ‘hill-edge’ is analogous to ‘moorland fringe’ or ‘upland marginal land’. In Wales, the hill-edge is a recognised agricultural component of upland farms, the ffridd. It is the highest enclosed land that provides seasonal grazing for livestock that are being moved uphill in the spring and downhill in the autumn. There is no equivalent name in general use in England but, in the Yorkshire Dales, the term ‘allotment’ is often applied to enclosed rough grazing land that is used in the same way as ffridd in Wales.
The chief characteristic of the hill-edge is the mosaic of habitats, which is the product of changes in landuse, particularly episodes of agricultural improvement followed by abandonment. This mosaic includes inter alia unenclosed rough grazing, enclosed grazing land that has been abandoned, bracken beds, wet flushes around spring heads, scrub, relict woodland, patches of dwarf shrub heath and grass moorland, and isolated improved pastures or hay meadows. The distribution of vegetation types on the hill-edge in England and Wales is mostly man-made, and does not reflect the natural altitudinal zonation of vegetation that still survives in parts the Highlands of Scotland and which is related to temperature and exposure to wind (McVean & Ratcliffe, 1962). Trees and scrub grow up to their physiological limits in some parts of the Scottish Highlands, such as the Cairngorms (e.g. Miller & Cummins, 1982), but equivalent tree and scrub lines are probably absent from England and Wales where most of the uplands have been deforested by Man in the past (Pearsall, 1950). Here, the current distribution of scrub and remnant woodland on the hill-edge is strongly influenced by grazing pressure (e.g. Hester & Miller, 1995).
This review was undertaken because of concerns about recent habitat changes, especially agricultural improvement, and their adverse effects on the plant and animal communities of the hill- edge, and because the hill-edge has been largely overlooked in the extensive literature on the uplands in Britain. As extensive areas of hill-edge habitats lie within most upland Environmentally Sensitive Areas (ESA) in England and Wales, the ESA scheme, together with the Countryside Stewardship Scheme, provides the means for targeting remedial measures at the hill-edge. However, the lack of current information on the hill-edge presents an obstacle to the formulation of appropriate conservation management prescriptions.
This is not the first report to examine the hill-edge in England and Wales. Two linked studies were undertaken in the early 1980s, by the Centre for Ecology and Hydrology (CEH; then the Institute of Terrestrial Ecology) (Ball et al., 1981;1982) and by the consultants Environment Information Services (Sinclair, 1983). These studies investigated changes in vegetation and land use on the hill- edge from a sample of 16 parishes distributed throughout the uplands of England and Wales. A third study, undertaken principally by Martin Parry and colleagues from Birmingham University, mapped land use changes in most of the upland National Parks in England and Wales and, in so doing, provided valuable information about changes in the extent and character of the hill-edge (Parry, 1977; Parry et al., 1981;1982a-f; 1984; Parry & Sinclair, 1985).
A fresh review of the hill-edge is justified for two reasons. Policy needs with regard to the management of agricultural land in the uplands of England and Wales have changed considerably since the early 1980s, particularly with the introduction of agri-environment schemes. This study is also able to draw on many datasets that were not available to the authors of the preceding reports.
1 Objectives
The review had the following objectives:
Objective 1 A. To characterise hill-edge habitats and to assess what is known about their species assemblages, physical characteristics and management features, using existing knowledge. B. To review the causes and extent of change in these features over recent decades and their impact on biodiversity. C. To identify gaps in current knowledge and recommend potential management options to enhance or restore the biodiversity value of these habitats.
Objective 2 To recommend further research work to fill gaps in knowledge identified in the review and consultation exercise.
Approach
The review was tackled in three ways:
1. Literature review 2. Consultations 3. GIS Analysis of mapped data
Literature review
Published literature was searched for using standard methods. However, a substantial proportion of references, including many of the most relevant ones, are either unpublished or are not indexed on computer databases. Their existence often only came to light as a result of consultations with the national conservation agencies and Non Governmental Organisations (see below). Many of the unpublished references are not readily obtainable. In some cases, very few or no copies appeared to have been retained in libraries on the Inter-Library-Loan network. The reference list in this report has, therefore, been annotated to give readers information on the contents of each reference source, but particularly on the unpublished ones.
Consultations
The primary aim of the consultation meetings was to collate the views of ecologists and land managers on the hill-edge and the conservation importance of hill-edge habitats. Most of the meetings followed a standard agenda, as follows:
1. DEFINITION OF HILL-EDGE HABITATS Are they a recognised component in the uplands nationally and in particular regions, especially Environmentally Sensitive Areas and National Parks?
2. SPECIES AND COMMUNITIES IN HILL-EDGE HABITATS How much is known? Priority species and communities?
3. HABITAT RELATIONSHIPS How much is known and is current knowledge adequate for the formulation of conservation management prescriptions for the agri-environment schemes?
2 4. OBSTACLES TO IMPLEMENTATION Identification of obstacles, especially agronomic, to the implementation of conservation management prescriptions which address hill-edge habitats
5. MONITORING DATA Plants Birds Other groups Aerial photographs and remote sensing information
The information gathered from the discussions has been incorporated in the literature reviews that follow and in the assessment of future R&D requirements.
The following organisations and individuals were consulted:
NATIONAL ORGANISATIONS AND SPECIALISTS
COUNTRYSIDE COUNCIL FOR WALES (Bangor) Barbara Jones, CCW Upland Ecologist Claire Burrows, CCW GIS specialist Adrian Fowles, CCW Invertebrate ecologist Liz Howe, CCW Species officer Jim Latham, CCW Woodland ecologist Hilary Miller, CCW Woodland policy Sian Whitehead, CCW Ornithologist
DEFRA RDS Ian Condliffe Andrew Cooke Robert Goodison David Martin Claire Millar Steve Peel Niall Watson
ENGLISH NATURE (Peterborough) Andy Brown EN Ornithologist - uplands Richard Jefferson EN Senior grasslands advisor Mick Rebane EN Upland specialist
GAME CONSERVANCY TRUST David Baines, John Calladine
LIVERPOOL UNIVERSITY (Applied Vegetation Dynamics Laboratory) Prof. Rob Marrs External Assessor of Uplands Assessment Unit of DEFRA
RSPB (Edinburgh) Murray Grant Jeremy Wilson Mark O’Brien James Pearce-Higgins Frances Winder
REGIONAL ORGANISATIONS AND SPECIALISTS
NORTH YORK MOORS NATIONAL PARK Peter Barfoot North York Moors National Park Authority Rona Charles North York Moors National Park Authority 3 Andrew Herbert North York Moors National Park Authority Rebecca Pickering North York Moors National Park Authority
YORKSHIRE DALES NATIONAL PARK Tim Thom Yorkshire Dales National Park Authority, Ecologist Ian Court Yorkshire Dales National Park Authority, Species Officer
PENNINE DALES ESA Martin O’Hanlon DEFRA Project Officer Helen Kemp DEFRA Countryside Stewardship Officer
PEAK DISTRICT NATIONAL PARK/NORTH PEAK ESA/SW PEAK ESA Rod Starbuck DEFRA North Peak ESA Project Officer Frances McCullough DEFRA RDS Wolverhampton Dean Kirtland DEFRA ESA assistant to Project Officer Steve Trotter National Trust, High Peak Estate Sophie Milner National Trust ecologist Richard Pollitt English Nature (Peak District) Chris Thompson Peak District National Park Authority species officer
DARTMOOR NATIONAL PARK/DARTMOOR ESA David Glaves DEFRA RDS Upland ecologist Andy Guy DEFRA Dartmoor ESA Project Officer Pete Stevens DEFRA RDS Ecologist Dartmoor ESA Sue Goodfellow Dartmoor National Park Authority Helen Booker RSPB (SW England) Simon Bates English Nature (Dartmoor)
GIS analysis
A key objective of the review was to characterise hill-edge habitats. This was done by estimating the areas of the hill-edge in England and Wales and of each of its constituent habitats from the CEH Land Cover Map 2000 (LCM2000). The LCM2000 data were reprocessed using GIS methods to generate maps of the hill-edge in all major upland regions of England and Wales.
Format of review document
The first section of the review document examines the habitat structure of the hill-edge and the processes that have determined its extent and habitat composition. The report moves onto to describe the GIS approach that was developed to estimate the area of hill-edge in England and Wales. Maps of each of the major upland regions of England and Wales are presented and these are accompanied by a set of matching tabulated data reporting the estimated areas of the constituent habitats.
In the second part of the review, the importance of the hill-edge to plant and animal communities is assessed. This part of the review has been split along taxonomic lines, and considers, in turn, plants, invertebrates, amphibians and reptiles, birds and mammals.
The third part of the review summarises what is known about the hill-edge and considers the implications of the current state of knowledge for the conservation management of hill-edge habitats and their plant and animal communities. Gaps in knowledge and requirements for future R&D are identified. The report is concluded with an annotated bibliography and technical appendices.
4 ORIGINS AND DYNAMICS OF THE HILL-EDGE
Summary
x The aims of this review were to identify the factors responsible for the development of the hill-edge, identify historical trends in land use change at the hill-edge and to consider their effects. x The mosaic of habitats on the hill-edge is largely the result of recurrent episodes of agricultural improvement and reversion. x The hill-edge represents the upper limit of cultivated or improved farmland. Its location on hill slopes is determined primarily by soils and climatic factors associated with altitude. Topography and land tenure are secondary determinants. x Agricultural improvement entails enclosure, removal of vegetation, drainage, ploughing, application of lime and fertilisers and reseeding. x The present day hill-edge landscape has evolved primarily from the period of enclosure at the end of the 18th and beginning of the 19th Century. Habitat mosaics are visible on vegetation maps and correspond fairly closely with areas of reclamation of rough pasture to improved farmland and reversion of farmland to rough pasture. x Long-term trends in land use change on the hill-edge in seven national parks in England and Wales – Northumberland, Lake District, Yorkshire Dales, North York Moors, Snowdonia, Brecon Beacons and Dartmoor - were reviewed using previously published surveys of historical maps and aerial photographs. x The conversion of rough pasture (moorland) into improved farmland (mostly grassland) and the reversion of agricultural land to rough pasture occurred throughout the 19th and 20th centuries. These changes would have promoted the development of habitat mosaics on the hill-edge. x The rate of habitat change increased in several, but not all, national parks after 1950 when more land was agriculturally improved than abandoned. x Afforestation with conifers was extensive after 1920, particularly in Northumberland, North York Moors, Snowdonia and the Brecon Beacons. Large areas of hill-edge will have been destroyed as a result.
The aims of this section of the review are to identify the factors that have resulted in the development of hill-edge habitats, to identify historical trends in changes in land use at the hill-edge and to consider their effects on the extent of hill-edge habitats. The effects of these changes in land use on the plant and animal communities of the hill-edge are considered in subsequent sections of the report.
The mosaic of habitats that characterises the hill-edge is largely the product of repeated episodes of agricultural improvement and reversion. In general, these changes in land use are associated with trends in agricultural market conditions at national and local levels, particularly the high-farming period of the 1850s, and the agricultural depression at the end of the 19th and beginning of the 20th centuries (Parry et al., 1981; Ball et al., 1982). More recently, the provision of hill-farming subsidies, following entry by the United Kingdom into the European Union and application of the Common Agricultural Policy, has promoted widespread agricultural improvement on upland farms and increases in livestock numbers, especially sheep (e.g. Sinclair, 1983; Dixon, 1984; Shrubb et al., 1997; Fuller & Gough, 1999). The timing and extent of these land use changes on the hill-edge are examined below.
5 The hill-edge represents the upper limit of cultivated or improved farmland, usually grassland, in the uplands. Its position on hill slopes is determined primarily by soils and climatic factors that are related to altitude and which limit agricultural activity (e.g. Dixon, 1984). Local topography may have a secondary effect, especially the steepness of the hill slope that precluded access by farm machinery prior to the introduction of specialist equipment and methods, such the winch plough and aerial spraying and fertilising (e.g. Lovegrove & Bowman, undated). Patterns of land tenure may also have had a significant impact in some areas. For example, rights of grazing on common land may have slowed agricultural improvement or prevented it altogether.
A detailed account of methods used in the agricultural improvement of hill-edge land is given by Dixon (1984). The main details are summarised here. The first step in the agricultural improvement of moorland or rough grazing is enclosure by the construction of walls, earth banks or even hedges, which is used to control grazing levels and establish ownership. Vegetation is then removed, or partially removed, to prepare the ground for seeding. Burning, cutting, cultivation or herbicides are used for this purpose. Where drainage is required, it is usually achieved by moor gripping, whereby open ditches, c. 0.5 m deep, are laid out in a ‘herring bone’ pattern on the hill slope. The prepared soil is sometimes cultivated but this has often been unsuccessful. In Wales, ploughed land on steep slopes tended to revert to bracken while, in wet areas, ploughing often promoted the germination of rushes Juncus spp. Liming is often necessary to increase the pH of the soil, while deficiencies in phosphates and nitrogen have to be corrected with fertilisers. Finally, the prepared land is reseeded with a seed mixes that usually contains perennial ryegrass Lolium perenne.
In some upland areas, relicts of field systems from the 11th Century are still visible (Parry et al., 1981) but the present enclosed landscape on the hill-edge probably originates mainly from the period of enclosure in the late 18th and early 19th Century. Elements of the habitats and landscape that preceded enclosure may survive either because the topography (e.g. steep slopes, exposed rock) was an obstacle to agricultural improvement or intensive grazing, or because patterns of land tenure, especially common land rights, slowed or prevented enclosure. These relicts contribute to the habitat mosaic on the hill-edge.
An example, from the North York Moors, of the mosaic of habitats on the hill-edge is shown in Fig. 2.1. Here the effects of improvement and abandonment respectively are visible in close proximity. A second example, also from the North York Moors, shows mosaics of dwarf shrub heath and grassland on the margins of unenclosed moorland adjacent to inbye land, the results of intensive grazing by sheep assisted by the agricultural improvement of the enclosed land (Fig. 2.2). The third illustration of the hill-edge is of the ffridd in Mid-Wales, where a mosaic of habitats is, again, evident (Fig. 2.3). The effects of afforestation with conifers are also visible in this case.
Habitat mosaics on the hill-edge are visible on Phase 1 habitat maps, as in the example shown from the North Peak ESA (Fig. 2.4). The reservoirs (shown in blue) in Longden Dale, and associated habitat mosaics on the valley slopes above, are shown near the southern margin of the map. There is a high degree of correspondence between hill-edge habitats and location of land that had either been reclaimed or allowed to revert between 1870 and 1970 (Fig. 2.5). This example is from the northern part of the Phase I habitat map shown in Figure 2.4.
6 Fig. 2.1. North York Moors showing enclosure of hill-edge and creation of habitat mosaics by agricultural improvement (=reclamation, sensu Parry et al., 1982a) and abandonment (=reversion sensu Parry et al., 1982a). The lower slopes beyond the track in the middle distance comprise enclosed and improved pastures. The enclosing walls of the pastures above are falling into disrepair. The land in the foreground and middle distance in front of the track has been abandoned. Bracken beds are extensive and encroachment by scrub and trees is underway. (Photo: Naomi Jones)
7 Fig.2.2. Habitat mosaic on the hill-edge in the North York Moors. The photograph shows enclosed improved pasture (inbye) abutting unenclosed moorland, with trees and scrub on the steeper slopes of a gill. The fragmentation of dwarf shrub heath, in the foreground, into patches of Calluna interspersed with grass is probably the result of intensive grazing by sheep.(Photo: Tim Milsom).
Fig. 2.3. Ffridd in Mid-Wales. A mosaic of rough grassland, bracken, scrub and deciduous woodland between improved grasslands in the valley bottom and unenclosed grass moor above. In the background, the right hand slopes of the valley have been afforested with conifers thereby eliminating hill-edge habitats. (Photo: Tim Milsom)
8 Fig. 2.4. Digitised Phase 1 habitat map of the northern part of the North Peak ESA.
Fig. 2.5. Location of areas of reclaimed (red) and regenerated (reverted) land (blue) (data from Parry, 1977) in relation to hill-edge habitats (darker green) shown in reprocessed Phase 1 habitat map.
9 Dynamics of land use and its effects on the hill-edge
The terminology used to describe the processes of agricultural improvement, reversion and afforestation was developed by Parry, Bruce & Harkness, who undertook geographical studies of the changes in the extent of moorland and roughlands in a sample of National Parks in England and Wales (Parry et al., 1982a-f, 1984). The term rough pasture was used to refer to moorland, rough grazing or roughland. Improved land referred to all wooded and farmed land that was not rough pasture. The term moorland edge referred to the boundary between rough pasture and improved farmland. Two types of conversion of rough pasture to improved land were recognised: reclamation to farmland and afforestation to woodland. Primary conversion was distinguished from secondary conversion. Primary conversion related to land that had not been previously cultivated whereas secondary conversion related to land that had been either reclaimed or afforested previously but which had subsequently been abandoned and allowed to revert to rough pasture. The term regeneration was used to refer to the reversion of improved farmland to rough pasture and to the deforestation of woodland. Regeneration was temporary if the regenerated rough pasture was subsequently re-converted to improved land, or enduring if the land remained as rough pasture in the 1970s.
Using a combination of cartographic material and aerial photographs, Parry et al. (1982a, 1982b, 1982c, 1982d, 1982e, 1982f, 1984) investigated the extent and nature of habitat change between c.1850 and c.1975 in seven National Parks in England and Wales. From north to south these were: Northumberland, Lake District, Yorkshire Dales, North York Moors, Snowdonia, Brecon Beacons and Dartmoor. The initial and final dates used in the assessments varied between areas depending on the dates of the source material.
The measures of habitat change employed by Parry et al. do not describe the hill-edge directly but they relate to processes that operate on the hill-edge and which have altered and continue to alter its extent and character. The first of these are the areas of rough pasture and improved land in each National Park (Fig. 2.6). There was a net loss of rough pasture to improved land between c.1860 and c.1980 in all National Parks except the Lake District, where there was no marked net change, and the Yorkshire Dales, where the area of rough pasture increased at the expense of improved land. The trends in the loss of rough pasture varied between areas and, in Northumberland, Brecon Beacons and Dartmoor, the long-term decline in the area of rough pasture was interrupted by temporary increases. These statistics give an approximate indication of the scale and timing of hill- edge creation, through regeneration, and loss, through reclamation, but they only record net changes and conceal the extent of habitat losses and gains that have occurred contemporaneously.
10 Northumberland North York Moors Lake District Yorkshire Dales 100,000 100,000 135,000 140,000
90,000 130,000 120,000 70,000 125,000 80,000 100,000 50,000 120,000 70,000 115,000 80,000 30,000 60,000 110,000
60,000 20,000 105,000 50,000
100,000
10,000 40,000 95,000 40,000 1860 1900 1940 1980 1860 1900 1940 1980 1860 1900 1940 1980 1860 1900 1940 1980 Year Year Year Year 100,000 76,000 56,000
Area (Ha) Area Snowdonia Brecon Beacons Dartmoor
74,000 54,000 70,000 72,000 52,000 50,000 70,000 50,000
68,000 48,000 30,000 66,000 46,000
20,000 64,000 44,000
62,000 42,000
10,000 60,000 40,000 1860 1900 1940 1980 1860 1900 1940 1980 1860 1900 1940 1980 Year Year Year
Fig. 2.6. Changes in areas of rough pasture (blue dashed lines) and improved land (red solid lines) in seven National Parks in England and Wales between c.1860 and c.1975. (Data from Parry et al.,1982a, 1982b,1982c,1982d, 1982e, 1982f, 1984).
Northumberland Yorkshire Dales 1800-1861 1800-1848 1848-1896 1861-1896 1896-1904
1896-1921 1904-1920
1921-1952 1920-1950 1950-1959 1952-1962 1959-1971
1962-1976 1971-1980
-5,000 0 5,000 10,000 -5,000 0 5,000 10,000 Area (ha) Area (ha)
Period Lake District North York Moors 1860-1895 1800-53
1853-95 1895-1903 1895-04
1903-1951 1904-50
1950-63 1951-1963 1963-74 1963-1974 1974-79
-5,000 0 5,000 10,000 -5,000 0 5,000 10,000 Area (ha) Area (ha)
Fig.2.7. Extent of enduring habitat change in national parks in northern England during different periods between c. 1800 and c.1980. Key: ochre bars – area of land converted to improved farmland, yellow bars – area of improved farmland reverted to rough pasture; dark green bars – area afforested; light green bars – area deforested. (Data from Parry et al.,1982a, 1982b,1982c, 1984).
11 Snowdonia Dartmoor 1800-87 1800-85
1887-03 1885-04
1903-48 1904-29
1948-59 1929-58
1959-75 1958-71
-4,000 -2,000 0 2,000 4,000 -4,000 -2,000 0 2,000 4,000 Area (ha) Area (ha)
Period Brecon Beacons 1800-85
1885-09
1909-48
1948-64
1964-75
-4,000 -2,000 0 2,000 4,000 Area (ha)
Fig. 2.8. Extent of enduring habitat change in national parks in Wales & SW England during different periods between c. 1800 and c. 1980. Key: ochre bars – area of land converted to improved farmland, yellow bars – area of improved farmland reverted to rough pasture; dark green bars – area afforested; light green bars – area deforested. (Data from Parry et al.,1982d, 1982e, 1982f).
A comparison of the areas of land reclaimed and regenerated respectively in different periods between c.1800 and c.1980 (dates vary between areas) provides a clearer record of the dynamics of land use in each National Park (Figs. 2.7, 2.8). The periods used in the comparisons are not of equal length because they were determined by dates of mapping and aerial photography and this places a constraint on the interpretation of the data. Nonetheless, the data are sufficient to show changes over time in the ratio of reclaimed to regenerated land. The most striking feature about the charts is that the patterns of land use change vary considerably between areas. The one consistent factor is the change in the extent of woodland. Extensive areas were planted after 1900 (but not before) whereas the corresponding areas of land regenerated by deforestation were very small by comparison. In Dartmoor, and to a lesser extent in the Yorkshire Dales, regeneration of agricultural land to rough pasture greatly exceeded reclamation in the 19th Century but the balance subsequently shifted so that, in the 1970s, more land was being reclaimed than regenerated. A similar shift in the balance between reclamation and regeneration also occurred in the North York Moors after 1950. In the other national parks, there was no obvious change over time. The locations of land parcels where either conversion or regeneration had occurred were mapped (Parry et al., 1982a-f; 1984). In the Lake District, Yorkshire Dales, North York Moors, Snowdonia and Brecon Beacons, most changes in land use tended to occur along the moorland edge. In Northumberland and Dartmoor, however, the parcels of land, where either reclamation or regeneration had occurred, were more widely distributed but they showed a moderately strong association with the moorland edge.
The next set of bar-charts shows the rates of reclamation of improved farmland in each National Park and distinguishes between primary and secondary reclamation (Figs. 2.9, 2.10). A degree of caution is required when identifying trends from the charts because the lengths of the sampling periods vary considerably. In the longer periods, short-lived conversions may have been missed resulting in under-estimates of the rates. Nonetheless, the charts do show that the rate of reclamation increased in many parks after 1950. Between c.1950 and c.1980, in the Lake District,
12 Brecon Beacons, and especially the Yorkshire Dales, reclamation occurred more rapidly on land that had been reclaimed previously and allowed to regenerate than on land previously uncultivated. Conversely, primary reclamation tended to be more rapid than secondary reclamation in Northumberland, Dartmoor and North York Moors. These descriptive statistics conceal the recurrent episodes of reclamation and regeneration that occurred at many sites. For example, in the Yorkshire Dales, the use of some land changed six times between 1848 and 1980 (Parry et al., 1984). Parry et al. (1982a-f; 1984) present additional statistics on the frequency of land use changes on parcels of land in each National park and on the rates of afforestation, deforestation and regeneration of rough pasture from improved farmland.
The survey by Parry et al. did not include data beyond 1980 and, in most areas, the cut off was c.1975 (Figs.2.7,2.8). Yet Shrubb et al. (1997) have suggested that, in Wales, the pace of habitat change accelerated during the late 1970s and 1980s, following entry to the European Union and application of the European Common Agricultural Policy to farming in the uplands. A follow-up analysis to that by Parry was undertaken by Silsoe College (Taylor et al., 1991). It assessed the degree of habitat change in the National Parks between the 1970s and 1980s. The period covered by the Silsoe College analysis overlaps by an unknown degree with that covered in the previous survey and the methods used to assess habitat change were different. Nonetheless, the Silsoe study provides some useful indicators to the patterns of change post 1980. Changes in the area of selected habitats that occur on the hill-edge are shown in Figs. 2.11 & 2.12. A complete list of habitats is given in Appendix 6 to Taylor et al. (1991). The main changes in land use were afforestation and reclamation of rough grazing. Extensive areas were planted with conifers in the Yorkshire Dales, Snowdonia and, especially, in Northumberland. Reclamation of rough grazing to improved pasture was most extensive in the Yorkshire Dales, Lake District and Snowdonia, whereas there was no evidence of reclamation in the North York Moors and Dartmoor. The areas of the hill-edge habitats in Dartmoor remained relatively unchanged.
Allowing for possible overlap with the data used in the previous survey, it is probable that, from 1970 onwards, the rate of afforestation increased in the Yorkshire Dales and North York Moors, and that the rate of reclamation of rough grazing to improved pasture increased in the Lake District and decreased in Northumberland and Dartmoor.
The trends identified by the Parry and Silsoe surveys are subject to the limitations imposed by the cartographic and photographic material that were available and the analytical methods that they were able to develop and use. The difficulties in identifying the transition between particular habitat types from aerial photographs are acknowledged by Taylor et al. (1991). Nonetheless, two major patterns of land use change and their effects on the hill-edge are clear. There is no doubt that extensive afforestation occurred in the National Parks, especially Northumberland, North York Moors, Snowdonia and the Brecon Beacons. It is likely that substantial areas of hill-edge habitat will have been lost as a result. The surveys also show that areas of rough pasture were reclaimed, and improved farmland was allowed to revert, throughout the 19th and 20th Centuries, in all National Parks, which will have promoted the development of habitat mosaics along the hill-edge until the 1980s. Extensive areas of improved farmland reverted to rough pasture in the Yorkshire Dales, and to a lesser extent in Dartmoor, in the mid-19th Century, thereby increasing the area of the hill-edge but much of this habitat was lost in the 1970s and 80s (Figs. 2.7, 2.8, 2.11, 2.12). Finally, the surveys by Parry and Silsoe College have highlighted that the long-term trends in land use change on the hill-edge, since 1800, have varied considerably between areas.
13 Northumberland Yorkshire Dales 1896-04 1896-21
1904-20
1921-52 1920-50
1950-59 1952-62
1959-71
1962-76 1971-80
0 50 100 150 200 250 0 50 100 150 200 250 Rate (ha yr-1) Rate (ha yr-1) Period Lake District North York Moors 1895-03 1895-04
1904-50 1903-51
1950-63
1951-63 1963-74
1963-74 1974-79
0 50 100 150 200 250 0 50 100 150 200 250
Rate (ha yr-1) Rate (ha yr-1)
Fig.2.9. Rates of primary and secondary conversion of rough pasture to improved farmland in national parks in northern England during different periods between c.1895 and c. 1980. Blue bars= primary conversion; red bars =secondary conversion. (Data from Parry et al.,1982a, 1982b,1982c, 1984).
Snowdonia Dartmoor
1903-48 1904-29
1948-59 1929-58
1959-75 1958-71
0 204060801000 20406080100
Period Rate (ha yr-1) Rate (ha yr-1) Brecon Beacons
1909-48
1948-64
1964-75
0 20406080100 Rate (ha yr-1)
Fig.2.10. Rates of primary and secondary conversion of rough pasture to improved farmland in national parks in Wales and SW England during different periods between c.1900 and c. 1980. Blue bars= primary conversion; red bars =secondary conversion.(Data from Parry et al.,1982d, 1982e, 1982f).
14 Coniferous Coniferous forest forest
Scrub Scrub Northumberland Yorkshire Dales Bracken Bracken
Heath grass Heath grass mosaic mosaic Heath bracken Heath bracken mosaic mosaic Improved Improved pasture pasture Rough Rough pasture pasture
-2,000 0 2,000 4,000 6,000 -2,000 0 2,000 4,000 6,000
Habitat Area (ha) gained or lost Area (ha) gained or lost
Coniferous Coniferous forest forest
Scrub Lake District Scrub North York Moors
Bracken Bracken
Heath grass Heath grass mosaic mosaic Heath bracken Heath bracken mosaic mosaic Improved Improved pasture pasture Rough Rough pasture pasture
-2,000 0 2,000 4,000 6,000 -2,000 0 2,000 4,000 6,000 Area (ha) gained or lost Area (ha) gained or lost
Fig.2.11. Extent of habitat change in national parks in northern England between 1970s and 1980s. (data from Taylor et al.,1991).Red bar = habitat gain; blue bar = habitat loss.
Coniferous Coniferous forest forest
Scrub Scrub Snowdonia Dartmoor Bracken Bracken
Heath grass Heath grass mosaic mosaic Heath bracken Heath bracken mosaic mosaic Improved Improved pasture pasture Rough Rough pasture pasture
-2,000 0 2,000 4,000 6,000 -2,000 0 2,000 4,000 6,000
Habitat Area (ha) gained or lost Area (ha) gained or lost
Coniferous forest Scrub Brecon Beacons
Bracken
Heath grass mosaic Heath bracken mosaic Improved pasture Rough pasture
-2,000 0 2,000 4,000 6,000 Area (ha) gained or lost Fig. 2.12. Extent of habitat change in national parks in Wales and SW England between 1970s and 1980s. (data from Taylor et al.,1991). Red bar = habitat gain; blue bar = habitat loss.
15 There is much less information on upland areas of England and Wales outside the national parks. The most intensively covered area is Mid-Wales where changes in land use were assessed by Parry & Sinclair (1985) and, again, by RSPB (1986). Parry & Sinclair showed that the area of rough pasture decreased by 29% from 101,483 ha, in 1948, to 72,481 ha, in 1983. This decrease was due primarily to afforestation with conifers. The rate of conversion of rough pasture increased during the survey period. The areas of the remaining habitats – improved farmland, broadleaf woodland and scrub and mixed-woodland - were more or less unchanged. In the second assessment, RSPB (1986) showed that 8,592 ha of moorland (12% of the area in 1971) had been lost between 1971 and 1985. Reclamation to improved pasture was more widespread than afforestation and accounted for 63% of the area of reclaimed moorland. Finally, Ball et al. (1981; 1982) examined long-term changes in a sample of parishes from 12 upland areas in England and Wales and produced estimates of moorland fringe (=hill-edge), the areas of reclaimed moorland and land that had reverted to moor (Table 6, in Ball et al., 1982).
No surveys, equivalent to those carried out by Parry and Silsoe College, have been carried out to assess changes in land use during the 1990s. However, substantial proportions of five upland National Parks – Lake District, Yorkshire Dales, Peak District, Exmoor and Dartmoor - have been declared Environmentally Sensitive Areas. The monitoring of land cover change in these ESAs (ADAS, 1996c, 1997c, 1997d, 1997e, 1997f, 1998a) will ultimately show whether the trends identified by the Parry and Silsoe College surveys have slowed down or reversed, but the data will require reprocessing before changes at the hill-edge can be identified.
16 HILL-EDGE – LOCATION AND EXTENT
Summary
x A probabilistic method entailing the application of GIS methods to mapped data from the CEH Land Cover Survey 2000 was employed to model the extent and habitat composition of the hill-edge in England Wales. x Classification of individual parcels of land to moorland, hill-edge and improved agricultural land respectively was based on their land cover category and those of adjacent parcels. The classification of hill-edge parcels was also determined on their proximity to significant areas of moorland. x Estimates were derived solely from land cover data and did not involve altitudinal criteria or reference to linear features, such as the moorland boundary wall. x The combined estimate from the major upland areas of England and Wales was 680, 175 ha. This estimate was derived from standard model settings that were applied uniformly to all areas of upland. x Separate estimates of the area of the hill-edge are produced for each of 12 upland areas in England and Wales. The areas varied from 5,812 ha in the Shropshire Hill ESA to 148,425 ha in the North Pennine Dales. The area of hill-edge in each area was compared with that of the core moorland. The median percentage of the core moorland area was 87% but the values varied from 31% in the North York Moors to 127% in the Shropshire Hills. The percentage for the Lake District was very much larger than the rest (203%), which raises uncertainties about the accuracy of the estimated area. x Details of the areas of each of the constituent habitats and a map are also presented for each upland area. The maps show the extent of moorland (ericaceous and grass), hill-edge habitats and conifer plantations. Boundaries of National Parks and Environmentally Sensitive Areas are also shown. x A sensitivity analysis was undertaken to evaluate the effects of adjusting the model settings on the area estimates. x The goodness-of-fit of the model was not formally tested because there were no extensive and independent datasets that described hill-edge habitats and which were contemporary with the satellite images used in the compilation of the LCM2000 map. However, the predicted extent of hill-edge in areas known to the authors was considered to be generally good in most though not all areas. The proportion of land in the Lake District that had been assigned to the hill-edge was higher than expected.
Background
Hill-edge is that component of the landscape that is at the edge of the hill. The definition is apparently simple but, upon examination, it requires some qualification.
x What is the ‘hill’? x How do we define where the edge is between hill and hill-edge (upper boundary)?
17 x How far does hill-edge stretch down slope into the larger upland landscape i.e. where is the boundary between hill-edge and other landscape components (lower boundary)? x What habitats and features, if any, characterise hill-edge?
The task is thus to map the upland landscape into three substantial and exclusive components (Fig.3.1). First is the ‘hill’, called here moorland, which often symbolises and defines the character of uplands in the UK. It is typically the highest component and is often actively managed. Second is a continuous and sometimes intensively managed agricultural landscape component, which tends to occur on the lower slopes and in the flatter bottoms of dales and valley bottoms. Though primarily pastoral in character, some arable farming does occur. Finally, the land in between contains characteristics of both the moorland above and the more intensively managed agricultural land below. Because it is often not actively managed for any single objective and sometimes is not managed at all, it appears to have no unique characteristics due to its management. However, it has been suggested that the very lack of coherent management across this transitional landscape component creates a distinctive and important mix of habitats.
Upper boundary to Core moorland the hill-edge
Moorland outlier Altitude Hill-edge Lower boundary to the hill-edge
Agricultural land
Figure 3.1. Diagrammatic representation of the position of moor, hill-edge and agricultural landscape components Initial analyses indicated that there are no intrinsic predictors of where hill-edge lies in the landscape. This lack of a unique and consistent character which can be used to define the hill-edge within the landscape appears to apply both to comparisons between upland regions across England and Wales and within individual upland regions. In the absence of habitat types or features unique to hill-edge, its delineation must rely on the description and mapping of its upper and lower boundaries. In turn, this requires the description of the location and extent of core moorland, its major outliers and of agricultural land present in the upland landscape.
When looking at the mapping process it becomes apparent that some features within the upland landscape as a whole do not fit into the analysis. This may be because they
18 are large enough to count as independent landscape features themselves and should not be counted as part of any landscape component (e.g. urban areas, plantation forests and reservoirs). Alternatively their position in the landscape should not contribute to this mapping exercise because they are man made and are placed in the landscape for historical and not ecological reasons (e.g. reservoirs and urban areas). Unfortunately, for historical and practical reasons most of these features are concentrated in the flatter agricultural landscape component and very few are found on the tops of hills. As such their presence may confuse the outcome of the mapping exercise, and for convenience, the area occupied by inland water and urban areas are excluded from the analysis altogether.
The course of the analysis undertaken was as follows:
1. Review of the data available to the project for the mapping of the upland landscapes at a national scale. 2. Study into the use of satellite derived data for the description of landscape components, including an understanding of the effects of geographical scale on the detection of hill-edge and of the qualitative and quantitative sources of error. 3. Mapped description of the current extent of moorland, hill-edge and intensively managed agricultural land in the uplands. 4. Characterisation of hill-edge habitats.
Prior to the objective characterisation and mapping of the hill-edge component in the upland landscape the literature was extensively studied, and interested parties were consulted, to build up a consensus picture of the character and function of both moorland and hill-edge landscape components in the upland landscape. This permitted the determination of a series of qualitative criteria and expectations that should be met by the mapping process before the quantitative description of hill-edge. These were as follows:
a. The description of moorland, hill-edge and agricultural landscape components should be as objective as possible. For example, historical and cultural descriptors of moorland, which identify land no longer bearing any ecological resemblance to moorland, must not be used. b. The moorland around which hill-edge is arranged is primarily that characterised by extensive and continuous ericaceous vegetation, including some moorland grass species, as well small patches of other habitat types. However, in some regions moorland comprises extensive areas of unmanaged grasses (dominated by Nardus and Molinia) without ericaceous herbage. There appears to be no unified and detailed description of which species (flora or fauna) the moorland habitat must support in order to qualify for the title ‘moorland’. c. The presence of ericaceous vegetation types is not unique to moorland. Where they are sparse or fragmented they can be considered not to be functioning as moorland in the ecological sense and thus not constitute ‘true’ moorland. d. These habitats occur at a wide range of altitudes, both nationally, and within any individual upland landscape. This precludes the use of altitude as a defining character.
19 e. Moorland is commonly perceived to exist in two main forms. As ‘core’ moorland, representing large continuous areas of moor supporting distinctive moorland species, and as isolated patches or ‘outliers’ which may or may not sustain their own characteristic moorland communities but are certainly seen to contribute to the sustainable ecology of the nearby ‘core’ moorland. Moorland habitats can also be found as scattered parcels throughout the wider landscape. Where these are small or distant from the ‘core’ moorland they probably have no functional role in the moorland eco-system and should not be considered to be part of the moorland landscape component. The classification of what size a patch of moorland habitats has to be to classify as core moorland, outlier, or functionally redundant moorland habitat appears uncertain. In addition, the distinction between an outlier and redundant moorland habitats is also seen to a function of its distance from the core. Consultees were reluctant to be held to quantification of either area or distance. f. Hill-edge is primarily found at the edge of core moorland, though not exclusively so. The mix of habitats that represent hill-edge may be found in pockets isolated from the actual fringe of core moorland and may still qualify as hill-edge if they satisfy one of two main criteria. Firstly, hill-edge may be present some distance from core moorland if it is associated with an ecologically functioning moorland outlier. Second, hill-edge may be found in complete isolation from moorland if it lies within 7 km of a core moorland feature. The second criterion is based on the premise that one of the main ecological functions of hill-edge is in its role supporting the biology of key moorland species such as Twite (Acanthis flavirostris) and Golden Plover (Pluvialis apricaria). Further discussion of this appears later. g. Hill-edge can contain habitats characteristic of both moorland (ericaceous shrubs) and agricultural land (intensively managed grassland or tilled land) though only in small proportions. It may contain higher proportions of sparse or poor quality moorland or less intensively managed grazing land. h. Hill-edge contains small patches of scrubby woodland. Extensive areas of natural woodland or plantation forests should not be considered as part of the hill-edge as they are large enough to count as independent landscape features.
Review of the data available to the project for the mapping of the upland landscapes at a national scale As an extensive component of upland landscapes, hill-edge is present across whole regions and its characterisation requires continuously mapped descriptions of land use, habitats, flora or other features across whole regions. There are very few such data sets available; those that are and their possible application for the purposes of this project are outlined below.
Ordnance survey mapping 1:10,000 scale Ordnance Survey mapping covers the whole of England and Wales and includes most features present in the landscape including woodland, walls, ditches and tracks. Where land is obviously boggy or marshy this too is displayed, though no boundary to this description is given and very little other information about habitats or vegetation can be inferred.
20 1Km
Fig. 3.2. Typical 1:10,000 Ordnance Survey mapping around Ewden, North Peak There are many references to ‘moors’ or agricultural practices in place names available within the maps. However, it must be remembered that these names fix the locations of past moor or agricultural practices in the cumulative historical landscapes since the first millennium. The type and location of agriculture and the use of the upland landscape has changed considerably in the last 1000 years, and place names hold little information about the current land use or habitat and its extent in the upland landscape. The ‘moorland wall’, taken by some as the upper limit of agricultural use in the uplands, often refers to a pattern of use in the landscape over 100 years old. Where it exists, this feature can be shown to be a poor predictor of the boundary of ecologically functional moorland because many areas of improved agricultural land have reverted to moorland below the wall, and because in many areas the character of unenclosed moorland above the wall has been so altered by grazing that it can no longer be classified as moorland. Further, for cultural reasons, the wall is present in some landscapes (e.g. Yorkshire Dales) though not consistently so, and is virtually absent in other landscapes (e.g. Dartmoor and the Brecon Beacons). The presence on a map of a feature such as the ‘moorland wall’ does not help in the objective description of the current national extent of core moorland or the hill-edge around it.
21 Land Cover Map Great Britain Produced by NERC sponsored research through ITE, the Land Cover Map Great Britain was the first attempt at a nationwide description of the distribution and extent of 25 broad habitat types within the UK. The mapped data were derived from a combination of satellite-derived imagery and field surveys, and the map is a coherent and complete description of habitats (based on their vegetative characteristics) in all upland areas. The country was divided into millions of land parcels measuring 25m x 25m each, corresponding to the maximum resolution of pixels in the original satellite images, and each was assigned a habitat class dependent on its reflectance signature at a number of wavelengths. The Land Cover Map Great Britain was derived from a series of satellite images taken during the late 1980’s and was produced in 1990. It will be referred to here as LCM1990.
1Km
Fig. 3.3. Typical LCM1990 data around Ewden, North Peak
LCM1990 is a spatially coherent product showing the fine detail in the composition and structure of the upland landscape. However, the data used to derive it are now 15 years old. In addition, whilst it gives a good general description of how a landscape is constructed, there are statistical issues about the quality of the habitat classification for individual pixels. Though it performed well in classifying habitats across extensive areas, caution is required when interpreting the representations of small landscape features within LCM1990. The habitat categories are also rather blunt for use within the context of this project.
22 Land Cover Map 2000 Released by CEH in March 2002, Land Cover Map 2000 (LCM2000) is a repetition and refinement of LCM1990. Using images gathered between 1996 and 2000, it employs a statistical process to first ‘coagulate’ neighbouring 25m x 25m plots into parcels of similar reflectance, and then identify these parcels with a greater statistical precision. The smallest parcel in LCM2000 is 0.5ha (effectively 24, 25m x25m pixels) though many parcels are much larger in landscapes with extensive and uniform habitats. The final product thus has a coarser spatial structure than LCM1990, but individual data are described with greater statistical confidence. Like LCM1990, it has complete national coverage.
1Km
Fig. 3.4. Typical LCM2000 data around Ewden, North Peak LCM2000 has many advantages. Like LCM1990, it is a spatially coherent product and a greater variety of habitat classes are distinguished. The data are recent. It is the most suitable spatially referenced source of information about the habitats covering the upland areas, for the production of an estimate of the current national stock of hill- edge and for the characterisation of the constituent habitats. However, its spatial structure is coarser than that of LCM1990, which may obscure smaller features in the landscape. In addition, there were no independently gathered data available to the project with which to verify its ability to accurately describe the location and extent of moorland and hill-edge landscape components. It was therefore not possible to achieve a detailed understanding of the absolute errors involved in estimating the extent and location of hill-edge, which would normally be quoted to qualify the estimate, though it was possible to carry out a sensitivity analysis (see Appendix 1).
23 Countryside Information System (CIS) CIS is another ITE/CEH product, describing many aspects of habitat distribution, land use, management and the disposition of various landscape scale features such as woodland. The data are presented as values representing occurrence or extent of the feature, habitat or land use within a 1km2 grid across the country. Unfortunately, the lack of any habitat or land use unique to hill-edge its identification from CIS difficult. Further, the imposition of a grid at 1km2 makes the identification of landscape features smaller than this impossible. As we knew a priori that hill-edge fragments could often be considerably smaller than this, CIS was dismissed as a suitable data set.
Aerial photography Two modern, complete and consistent commercial aerial photography products are available covering the uplands in the UK. Unfortunately, three issues make their use unfeasible in this case. Firstly, analysis of a statistically worthwhile subset of potential upland images would be prohibitively costly. Secondly, though the colour images are of good quality they are still inadequate to discriminate the subtle differences between various grades of upland grass habitats or determine the density of heather canopy. Even if the images were of a quality to allow this, a third fundamental issue arises. The use of aerial photography would require an operator to use the image as a guide to draw the boundaries between core moorland and hill-edge, and hill-edge and agricultural land. This would become a subjective and personal assessment of the extent and location of the landscape components, and the technique would be prone to the same issues of repeatability, accuracy and consistency that affect Phase 1 surveys.
Ad-hoc data During consultations with interested parties, it has come to light that extensive surveys of land use, habitat or vegetative cover had been conducted in the past. Many, if not most, of the regions designated as ESA’s were subject to a Phase 1 or Phase 1+ floristic survey. Some of these appear to have been lost. Some were accessible though still in their original paper and pencil format. As these are large and detailed datasets their use as part of a detailed and wide ranging analysis would require them to be converted into a digital format suitable for a GIS. This conversion was beyond the scope of this project. Nevertheless at least two Phase 1 habitat maps have been fully digitised and were available to this project as spatially referenced databases; those for the North Peak and South West Peak ESAs. Unfortunately, they have used different recording approaches and both suffer from the biases to which all Phase 1 surveys are prone. However, all of these Phase 1 surveys represent an unparalleled and valuable resource identifying the location, extent and type of vegetation covering the ESAs.
The two digitised Phase 1 surveys were surveyed in 1991 and were therefore contemporaneous with LCM1990. They were used here in conjunction with LCM1990 to validate the use of satellite data for the detection on moorland and agricultural landscape components, and identify issues surrounding its use.
24 Fig. 3.5. Typical Phase 1 mapping within North Peak ESA, around Ewden, North Peak.
Summary
x In order to estimate and characterise the hill-edge, it was necessary to map the upland landscape, with the exception of inland water and urban areas, into three exclusive landscape components: moorland, intensively managed agricultural land and hill-edge. x This mapping was performed on the basis of the composition and extent of the habitats present on the ground. x As there is no habitat or suite of habitats unique to hill-edge, the moorland and intensively managed agricultural components were defined and mapped. The landscape not described as characteristically moorland or agricultural was considered to represent the hill-edge. x Mapping was restricted to within 7km of ‘core’ moorland features. x Commercially available data sets describing the land cover across all UK upland regions were used for the mapping process (LCM1990 and LCM2000).
25 Study into the use of satellite derived data for the description of landscape components.
The LCM1990 satellite data set was selected to validate the use of remotely sensed data in the determination of hill-edge for three reasons. First, it is contemporaneous with the only complete upland Phase 1 data available to the project. This allows some corroboration of satellite based mapping with data collected on the ground. Second, its description of the fine scale structure of the habitats in the landscape allows a determination of the spatial sensitivity of any description of hill-edge to changes in the spatial coarseness of the data available. Third, the novelty and statistical complexity of LCM2000 data make its use subject to as yet unknown limitations.
Analytical approach The analytical approach used was analogous to standing on every spot in an upland landscape, looking around and deciding, on the basis of the types and extent of the habitats present close by, whether the spot was part of the moorland, agricultural or hill-edge landscape components. In analytical terms, different habitat classifications within a LCM1990 map were assigned differing numerical weights. The landscape classification model then examined every pixel in the map and produced a value for that pixel as a function of the habitats (and their values) around that point. The classification of any individual pixel was more clearly related to the habitat at that point and in its vicinity than to habitats at some greater distance. Thus a circular area of interest was described around the pixel under classification, which was used to limit the number of neighbouring pixels included in the analysis model. This area around the pixel under classification was defined by its radius and is termed here the scope.
Fig. 3.6. Diagrammatic pixel grid showing scope around central pixel of interest. Black pixel is the pixel of interest; other colours mark increasing scope at 25m intervals.
26 The habitat values of the pixels encircled within the scope of interest were examined and summed. Those habitats uniquely characteristic of a moorland landscape component were given a maximum weighting (arbitrarily set at the value 12). Those habitats uniquely characteristic of an agricultural landscape component were given a minimum weighting (zero). Those LCM1990 target classes that are ubiquitous across the uplands and independent of the landscape component in which they occur were assigned an intermediate weighting (the value 6) designed to act neutrally in the determination of landscape component. All pixels which contained a habitat assigned values of 0, 6 or 12 were subsequently characterised as part of the either the moorland, agricultural or hill-edge landscape component. A fourth category was used for classes that were excluded from assignment to any landscape component, and their spatial locations are not characterised. The values assigned to each habitat are shown in Table 3.1.
Table 3.1. The 25 target classes used in LCM1990, and their role in the characterisation of the upland landscape. * denotes a unique value used to characterise extensive grass moorland landscapes.
ITE target class name Uniquely characteristic of No weight in Location not Assigned analysis characterised weighting value in analysis Moorland Agricultural land ITE Target class code Sea/Estuary 1 9 Null Inland water 2 9 Null Beach Coastal bare 3 9 Null Saltmarsh 4 9 Null Grass heath 5 9 6 Moorland grass 9 9*7 Mown / Grazed turf 6 9 0 Meadow / verge / semi-natural 7 9 6 Ruderal weed 19 9 6 Felled forest 23 9 6 Rough / marsh grass 8 9 6 Open shrub heath 25 9 12 Open shrub moor 10 9 12 Dense shrub heath 13 9 12 Dense shrub moor 11 9 12 Bracken 12 9 6 Scrub / Orchard 14 9 6 Deciduous woodland 15 9 6 Coniferous woodland 16 9 6 Lowland bog 24 9 Null Upland bog 17 9 12 Tilled land 18 9 0 Suburban / rural development 20 9 Null Continuous urban 21 9 Null Inland bare ground 22 9 Null Unclassified 0 9 Null
27 The final value of every pixel describes its position on a scale between the maximum numerical value, representing ‘pure’ moorland, and the minimum numerical value, representing ‘pure’ intensive agricultural land. The actual determination of which landscape component the pixel is assigned to is dependent on the numerical thresholds used to represent the upper and lower boundaries of the hill-edge habitat. The hill- edge and grass moorland landscape components sit as intermediate values between the exclusively moorland or agricultural.
One LCM1990 habitat classification, moorland grass, was given a unique value, seven. The reflectance values characteristic of moorland grass appear frequently throughout the LCM1990 map, sometimes as individual or scattered pixels, sometimes as small discrete parcels and sometimes as extensive areas composed purely of this individual habitat description. This may be because the moorland grass habitat really was ubiquitous in the upland landscape at the time the satellite images were taken, or alternatively, that its reflectance values are close to or easily confused with other habitat types (especially other upland grassland types) and that these classifications are an artefact of the LCM1990 interpretation. Because of this, moorland grass was originally deemed to be independent of the definitive moorland description and given a neutral value in the analysis (6). As this produced serious anomalies in the model, moorland grass was given a value that would improve the fit of the moorland landscape component and allow extensive continuous areas to be identified independently of hill-edge.
As this approach is sensitive to both the scope and the thresholds used to characterise the pixel as either moorland or intensive agricultural, we conducted a sensitivity analysis to determine optimum values for both. The sensitivity analyses were confined to the areas within the North Peak ESA and the South West Peak ESA, which represent the only independent and alternative landscape scale habitat descriptions available. A description of the methodology applied in the sensitivity analysis is included in Appendix 1. In addition, the model was also run for the North York Moors. The maps resulting from the model predictions were compared with our own local knowledge and areas were visited to inform our perception of both the character of hill-edge on the ground and the qualities of the model in identifying the landscape component from satellite derived data.
Results The model was subjected to a comprehensive sensitivity analysis for the two major variables which would affect the qualitative and quantitative estimates of the position and extent of the moorland, intensive agricultural and hill-edge landscape components: the spatial scope of the model, and the thresholds used to determine the characterisation.
The intensive agricultural landscape component was defined by its composition as the area which comprised at least 50% coverage by known intensive agricultural land cover types. The moorland landscape component was defined by the quality of its comparison against the Phase 1 data available to the project. Examples of typical output from the model can be found in the section describing the current extent of hill-edge.
28 Discussion
The use of satellite data in mapping the upland landscape. Satellite data, available here in a calibrated and interpreted form, are unique in allowing a comprehensive and objective description of the land cover across whole geographical regions. For these reasons alone it must be the data set of choice for studies such as this. However there are issues that must be addressed before we place any weight on the interpretation of satellite derived data.
As the final step in the interpretation of satellite data into the LCM1990 and LCM2000 products, CEH ascribe to each pixel or parcel a habitat description best fitting the reflectance values for that spot on the map. Having decided that the moorland landscape component is characterised by ericaceous and bog habitats, why not simply lift these habitat descriptions straight from the map and use these to delimit the moorland landscape component? The direct acceptance of parcel or pixel habitat descriptions for both LCM1990 data and LCM2000 data is inadequate in the production of the landscape component model because there may be simple non- systematic errors in the interpretation of the reflectance data. For the individual pixels within LCM1990, such error may be a significant but unquantifiable source of inaccuracy. However, the greater the continuous land cover attributed to a single habitat, the lower the chance that the entire parcel has been incorrectly characterised. Thus some of the extensive dense shrub heath and moorland grass reflectances found within LCM1990 maps of the uplands are probably reliable. However, a number of circumstances may result in the systematic misinterpretation of even large areas of land cover, for example, in areas with strong topographical features (including many upland areas), strong shadow may force significant and difficult to detect errors in satellite derived data that can only be exposed with validation by ground surveys. These errors are strongly reduced in LCM2000, but the consequences of incorrect interpretation of the reflectance values become more serious where the character of a whole parcel is affected rather than an individual pixel.
In addition, the direct use of only habitat descriptions thought characteristic of any individual component excludes the potential inclusion of other habitat types commonly found scattered through the upland landscape. Moorland as a landscape feature, though composed primarily of ericaceous habitats, upland bog and moorland grass, will contain small proportions of other habitat types, including small-scattered parcels of intensively managed grassland or tilled land. Where surrounded by moorland habitats these atypical moorland components need to be incorporated into the description of the moorland landscape. Using only a direct description of habitats would not account for this and would produce a description of the moorland landscape component that was more highly fragmented than necessary.
Consequently, an approach is needed that moderates both the description of the habitat itself according its similarity to its neighbours and also according to its size in the landscape. We believe that the model presented here achieves this.
29 Character of the modelled landscapes – LCM1990
Agricultural land The definition of agricultural land is essentially one of land-use and not habitat cover. As LCM1990 only describes broad habitats we cannot hope to know where, and of what type, agricultural land-uses are. As such we cannot model all agricultural land using LCM1990 or LCM2000. However, these datasets do allow us to determine which areas have received particularly consistent or intensive land management as some of the land cover types imply particular land-uses. Where distinct parcels or consistent areas of the tilled land or the intensively mown/grazed turf vegetation cover types are seen, an intensive land use can be implied. Our definition of the intensive agricultural landscape component is thus restricted to areas with a sufficient density of intensively managed pastoral (fertilised or grazed turfs) or arable land.
For other broad habitat types found within LCM1990, some agricultural use may exist including grass heath, moorland grass, meadow/verge/semi-natural and ruderal weed. These reflectances, present either as coherent patches or as an intimate pixel by pixel mix (e.g. Figure 3.3) suggest a lower intensity or less consistent form of land management. As all of these broad habitat types do not represent ecological climax communities, some managed land-use can be inferred. If this land had been abandoned, it is likely to have been an ecologically recent abandonment. Present in a largely intensive agricultural landscape, parcels of these habitat types were classed as agricultural.
As a further complication, the above list of grassland habitat types is not even necessarily distinct or consistent. Satellite images, even those compiled across multiple bandwidths, and the composite reflectance values within each pixel may differ for many reasons. These are primarily related to land cover, though land use and the immediate details of the image capture (soil hydrology, aspect, time of day and shadow areas) all affect the interpretation of the images. Where habitat types share similar reflectance characteristics, as do the grassland types, confusion between types is likely. Thus it is important, especially when calculating landscape scale features, that limited weight is put on what may be spurious differences in the descriptions of the LCM1990 grassland habitat types.
In this analysis, the ‘neutral’ role given to the grass heath, moorland grass, meadow/verge/semi-natural and ruderal weed habitat descriptions results in their presence near intensively managed agricultural land being given an agricultural role. As small patches within a largely moorland landscape they may represent a small vegetated scar or fresh re-growth after a moorland burn – and would suitably be classified as part of the moorland landscape. Present alone in the upland landscape it is difficult to discern land use or its intensity, but we can infer that the named grassland habitat types are managed though not intensively grazed.
The establishment of the threshold at a value where 50% of the land labelled as the agricultural landscape component is of identifiably agricultural land cover (e.g. the tilled land or mown/grazed turf reluctances), is essentially arbitrary, there being little precedent in this area. Whilst some debate over the exact figure may result in a small
30 change in the target proportion of agricultural land within the agricultural landscape component it is worth noting a number of points. 1. This threshold is designed to separate land intensively managed for mainstream agricultural production from that managed at lower intensities. A requirement for a higher percentage of agricultural land cover within the agricultural landscape component reduces the agricultural landscape component to small pockets within a matrix of the hill-edge component (representing the next gradation in lowering agricultural intensity). Whilst not ‘wrong’, landscapes mapped under such a higher threshold have extensive areas of hill-edge and a greatly reduced agricultural component and appear counterintuitive. 2. The LCM1990 map has a spatial resolution of 25mx25m. It identifies most of the pockets of land where management intensity has been reduced or it has been temporarily abandoned (e.g. set aside, poorly established crops) as non-agricultural uses. In addition there are substantial areas, even in a rural lowland agricultural landscape, given over to apparently non agricultural habitats; woodlands, roads and their verges, substantial hedgerows, flood meadows etc. All of these will combine to lower the proportion of land in any given agricultural landscape that can definitively be described from satellite data as being under agricultural production.
Moorland landscape component It is unfortunate that one of the primary definitions of hill-edge is its presence at the edge of the moorland landscape component. The authors have felt from the outset that whilst the description of the extent and location of hill-edge may provoke only a minor interest with the public, landowners and other vested interests, the consequential description and mapping of the moorland landscape may itself cause some contention.
The discussion of this subject with interested parties and between the authors has been informative. The cultural and professional interests that are sponsored by moorland are many and it was challenging to define either the moorland habitat and its unique signature eco-systems, or the moorland landscape, without disagreement. To try to overcome difficulties that arise from yet another description of moorland and its qualities and uses, we try here to define the moorland landscape component. This is intended to be a more general description than merely the location of shrub heath and wet bog habitats, and we distil from this the areas of the larger upland landscape that function as a coherent whole, encompassing mixed land uses and mixed land covers. The use of LCM1990 and LCM2000 data, produced from satellite imagery in a largely unrestricted manner, removes the influence of cultural, historical or even political bias. In places however it may differ from previous descriptions of the extent and location of moorland.
The moorland landscape component is defined within the model by the presence of extensive areas of Upland Bog, Open Shrub Heath, Open Shrub Moor, Dense Shrub Heath and Dense Shrub Moor as described within LCM1990. Although lowland heath and moorland habitats can sometimes be distinguished on the ground, their similar reflectance within satellite images results in greater confusion between the two within the land cover maps. Even if a reliable botanical formula were available to separate lowland heath and ericoid upland moor following Phase 1 or Phase 2
31 methodology, it is unlikely that any remote survey method would be able to separate these broad habitats, and cultural factors would be used to describe their location. As our approach tried to avoid undue ‘contamination’ from cultural pre-conceptions we deliberately combined the LCM1990 Shrub heath and Shrub moor classifications. In practice this does not present a problem because our analysis was restricted to a 7 km radius of major upland areas in England and Wales and with two exceptions (Dartmoor and Exmoor) there is unlikely to be any confusion with known lowland heath habitats.
Other habitat types (or their reflectance signatures) are present within the moorland, though their inclusion within the description of core moorland depends upon the extent of the habitat, its type and its location. Typically, small enclosures (<1ha) of intensively maintained turf might still be included as a moorland feature if completely isolated within many hectares of dense shrub moor. The same field surrounded by extensive areas of sub-moorland habitat types (moorland grass, rough/marsh grass) or at the edge of continuous shrub moor might not qualify as part of the moorland landscape.
The division of moorland into core moorland, moorland outliers and non-moorland ericoid habitats is somewhat artificial but is required to separate those areas which are likely to function as ecologically independent areas of moorland from those areas which because of their small size or isolation, though composed of ericoid vegetation, have lost their moorland eco-system. When questioned as to what they considered to be the limits on size and distance to isolation, consultees were reluctant to be held to numerical descriptions. Unfortunately, such parameters are necessary in an objective mapping exercise, so we selected values justified as follows:
x Core moorland exists as a continuous mapped feature with an area exceeding 1000 ha. Though arbitrary, this criterion neatly identifies all of the ‘major’ upland areas in England and Wales. The area of the moorland landscape component within any upland region will be larger than this as it may include multiple core moorland features, as well as a variable area composed of outliers. x Moorland outliers have an area exceeding 10 ha of continuous moorland habitats and are within 5 km of a core moorland feature. Work within the project has shown that for the North Peak, South West Peak and North York Moors, this definition of moorland outliers includes 96% of the moorland parcels present within the upland landscape and 98% of the area of ericoid and bog vegetation.
Moorland grass The estimate of the scale and location of core moorland produced by the model was largely restricted to the ericaceous habitat types (bog habitat types seem poorly represented in LCM1990). Whilst probably constituting the largest and most important unique vegetation types within any subjective description of moorland, the restriction of an objective moorland description solely to ericaceous and bog habitats produced some unusual results and was felt to be inadequate. Also, the allocation of the moorland grass habitat classification to a numerical value which gave it no independent weight also inhibited the identification of a unique sub-type, grass moorland or ‘sheep walk’, characteristic of some areas of central Wales or Teesdale. Whilst it may not constitute ‘true’ moorland in ecological terms, and may be
32 considered a degraded landscape habitat produced by historical or current overgrazing, its cultural association with upland areas is strong enough for us to wish to differentiate it from the other sub-moorland landscape component – hill-edge.
The selection of the numerical value of seven for the unique differentiation of extensive areas of moorland grass was not arbitrary. This value represented the equivalent threshold value used to differentiate moorland from hill-edge before the re- assignment of the moorland grass habitat. In giving the moorland grass habitat this value it was felt that the distinction of grass moorland would result in a reduction in the area attributed to heather moorland but not significantly change the location or extent of the hill-edge. However, this was found not to be the case. Within the model, the differences between grass moorland and hill-edge are minimal. Both are often dominated by grassland types, with the differences being in the degree and intimacy of the variation in grass habitat types. Grass moorland is defined as extensive and more or less continuous habitat, whilst hill-edge is often characterised by a less extensive and more mixed habitat composition, though still dominated by the moorland grass habitat. Given the uncertainty about the differentiation of grassland types within LCM1990 it could be argued that hill-edge and grass moorland are both closely related types of sub-ericoid ecotones, the former the result of indifferent management and the latter the result of over grazing.
Many of the pockets of pure moorland grass putatively described as grass moorland should not be so described, being too small to qualify for the cultural description. Unfortunately, we can find no description of the minimum size that an extensive patch of pure moorland grass should be before it is designated grass moor, so we simply describe the extent of this habitat without assuming that the areas described are continuous.
Hill-edge After accounting for settlements, reservoirs and extensive plantation woodlands, the remaining landscape component is defined as the hill-edge. This represents a mix of habitat types of indefinable overall character, and would result in the inclusion of much land across the UK as the hill-edge habitat. Thus this study limits itself to an analysis within 7km of a core moorland complex. It is important to stress that it is the combination of habitats and their position in the landscape that make hill-edge unique. Hill-edge as a landscape component is not usually dominated by any one habitat type, but different regions show distinctive differences in the composition of the hill-edge.
The choice of a 7 km cut off for the description of hill-edge is based in part on its perceived role in the ecology of certain key moorland bird species. Hill-edge is thought to act as an essential component in the feeding ecology of a number of species of conservation interest, some of the best understood of which are birds e.g. twite, golden plover and black grouse (Tetrao tetrix). Golden plover travel between 2 and 11 km from core moorland to find suitable feeding sites within the hill-edge, so 7 km was chosen as an approximate median value. This value was also found to produce a satisfactory model fit for the areas for which the authors had personal knowledge.
33 Choice of scope in the model The sensitivity analysis for the characterisation of landscape components within the model was designed to measure the effects of changing spatial scale on the quality of the output. A thorough understanding of the effect of scale was necessary because hill-edge was known a priori to occur as both extensive areas (measured as kilometres) and is very small patches or ribbons along the moorland fringe (measured as a few tens of metres). In addition it was known that the data available for the production of the current estimate (LCM2000) are presented at a coarse spatial scale. There was concern that the spatial and descriptive smoothing processes that occurred during the production of LCM2000 might therefore obscure hill-edge.
Small scopes of interest (e.g. 25 or 50 m) limited the analysis to an examination of a few neighbouring pixels within this radius around a pixel of interest and produced a landscape model very responsive to small changes in the disposition of different habitat types. Thus misclassifications of individual pixels in the original LCM1990 dataset would have large effects on the description of the landscape component, and the resultant map of moorland would be as highly fragmented as the original data. Large scopes (>500m) encompass thousands of pixels, and allow small local variations in habitats to be diluted, producing a more ‘smoothed’ description of the upland landscape components. However, at such scales the effects of habitats at substantial distances from the pixel of interest play a role in its description and the edges of the moorland features are seen to ‘retreat’ as their moorland character is diluted by the presence of non-moorland and agricultural habitats.
The selection of the actual scope to use in the national description of hill-edge, a value of 250m, was felt to be the ideal intermediate, offering a sensible balance between the best ‘quality’ model prediction (using scopes of 175m or 200m where the ratio of incorrectly to correctly identified moorland was smallest) and the best ‘quantity’ description (using scopes of 350m where the simple proportion of known moorland was correctly identified as such by the model).
A scope of 250m represents a circle of diameter 500m within which habitats are examined and processed to produce a characterisation of landscape component at a 25m x 25m spot. Using LCM1990 data this presents no difficulty, since every 25m x 25m spot is independently described as belonging to one habitat or another. LCM2000 uses various processes to spatially and statistically moderate the description of the habitat at a point and this may confound the model. However, across most landscapes, LCM2000 parcel sizes are smaller than the selected scope, for example only 1.5% of parcels around the North Peak ESA have an area larger than a circle of radius 250m. More importantly, with a scope set at this size, most 25m x 25m plots will be influenced by a number of parcels, each with its own independently determined habitat classification.
Thus although the extent of spatial smoothing and the moderation of the habitat classification undertaken by the model using LCM2000 data will be lessened, this is only because these processes have already been undertaken by the producers of the data set itself.
34 Current national estimate of hill-edge in England and Wales
LCM2000 data was compiled from satellite images and processed to form land parcels of similar habitat. The data was converted back into a grid form, with the grid elements measuring 25m x 25m and presented to the model, set with a scope of 250m and with thresholds of 38.4%, 57.2%, 58.4% representing the boundaries between agricultural and hill-edge, hill-edge and grass moor, and grass moor and heather moor respectively.
The model was run across extensive areas of England and all of Wales to identify both those areas of continuous moorland which exceeded 1000ha, but also the extent of the hill-edge within 7km of this moorland. This is presented as maps on the following pages. The total areas (in hectares) of the agricultural, hill-edge, grass- moorland and heather-moorland landscape components are given, for the natural feature (all land within 7km of the core moorland) and for that proportion that lies within the boundaries of Environmentally Sensitive Area (ESA) and/or a National Park found in that region. The figure for hill-edge within the natural feature is given in two forms. The first represents the potential area of hill-edge including coniferous woodland. The second, lower figure is the adjusted area of hill-edge excluding coniferous woodland. The difference between the figures is an indication of the extent of coniferous plantations within the landscape that might otherwise be occupies but the more usual mix of habitats found within the hill-edge landscape component.
The adjusted regional estimates for hill-edge are also presented in a summary table (Table 3.2) so that the disposition of hill-edge can be seen. Also included is a single figure representing the total estimated stock of hill-edge across England and Wales. The composition of the hill-edge was then determined by selecting those LCM2000 land parcels whose centres fell within the description of hill-edge, and by summing the areas for each habitat classification. These figures are presented for each region as a percentage of that habitat type within the overall landscape component. A breakdown of habitat compositions within each of the regions is included in the regional summaries.
Table 3.2. Summary table of total adjusted estimates of hill-edge by region. Region Area of moorland (ha) Area of hill-edge (ha) Area of hill-edge as a % of the moorland area (1) Northumbria 67099 39125 58 North Pennine Dales 187449 148425 79 Lake District 41461 83951 203 North York Moors 46597 14545 31 Forest of Bowland 18267 14625 80 South Pennine chain 79415 85151 107 Shropshire Hills 4602 5812 127 Snowdonia 139023 123283 89 Mid-Wales ESAs 78257 80751 103 Brecon Beacons 64670 55011 85 Exmoor 7622 8546 112 Dartmoor 30151 20950 69 Total - 680175 - Notes: (1) excluding conifer plantations
35 Table 3.3. Summary of the percentage of LCM2000 habitats within four landscape components for Northumberland Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 4.2 2.8 0.3 1.1 Mixed broad leaved woodland 1.1 1.6 1.3 1.4 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 2.3 42.3 11.1 4.6 Felled conifers 0.0 2.8 1.5 0.8 New conifer plantation 0.2 1.0 0.2 0.2 Arable cereals 12.4 0.2 0.0 0.0 Arable horticulture 14.6 1.2 0.5 0.5 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.1 0.0 0.0 0.0 Improved grassland (intensive) 44.5 1.2 0.3 0.2 Improved grassland (grass (hay/ silage cut)) 8.6 1.0 0.2 0.3 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.4 0.1 0.0 0.0 Neutral grass (rough) 1.7 3.8 0.7 1.4 Neutral grass (grazed) 2.3 20.4 2.8 2.7 Calcareous (rough) 1.6 2.1 0.3 0.2 Calcareous (grazed) 2.9 2.0 0.3 0.1 Acid grass 0.2 2.6 15.3 5.2 Acid grass (rough) 0.5 1.4 1.6 1.0 Acid grass with Juncus 0.0 0.1 0.4 0.1 Acid grass with Nardus/Festuca/Molinia 0.2 5.9 56.9 11.1 Bracken 1.4 4.6 1.7 1.5 Dense (ericaceous) dwarf shrub heath 0.1 1.0 0.8 7.3 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.3 1.2 2.8 48.2 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.1 0.2 2.0 Bog (grass/shrub over deep peat) 0.0 0.1 0.3 6.3 Bog (grass/herb over deep peat) 0.0 0.3 0.4 3.2 Bog (undifferentiated over deep peat) 0.0 0.1 0.1 0.5 Semi-natural bare ground 0.0 0.1 0.0 0.1 Despoiled bare ground 0.0 0.0 0.0 0.0
36 Table 3.3 (Cont’d). Areas of LCM2000 habitats within four landscape components for Northumberland Agriculture Hilledge Grassmoor Heathermoor 81903 Area covered 104202 (39125) 7018 60081 Area covered within National Park boundary 15579 32378 4987 29798 Northumberland: dominated by coniferous plantation and grassland (particularly neutral) with some Pteridium and semi-natural woodland.
Fig. 3.7. Extent of hill-edge habitats in the Northumberland National Park and adjacent areas. Key: Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage.
37 Table 3.4. Summary of the percentage of LCM2000 habitats within four landscape components for Lake District Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 4.7 7.0 0.8 1.6 Mixed broad leaved woodland 0.4 1.2 0.5 0.4 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 0.9 4.6 1.6 1.9 Felled conifers 0.0 0.2 0.1 0.0 New conifer plantation 0.0 0.1 0.0 0.2 Arable cereals 2.7 0.1 0.0 0.0 Arable horticulture 8.1 0.5 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.7 0.0 0.0 0.0 Improved grassland (intensive) 48.5 1.7 0.2 0.3 Improved grassland (grass (hay/ silage cut)) 17.3 1.6 0.1 0.3 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.8 0.9 0.0 0.0 Neutral grass (grazed) 2.6 16.8 1.7 3.4 Calcareous (rough) 5.6 4.8 0.4 0.4 Calcareous (grazed) 0.9 0.2 0.0 0.0 Acid grass 2.5 21.0 72.1 31.4 Acid grass (rough) 0.5 1.3 4.5 1.6 Acid grass with Juncus 0.2 0.5 0.5 0.9 Acid grass with Nardus/Festuca/Molinia 0.1 0.9 6.7 2.9 Bracken 2.6 34.0 8.1 6.1 Dense (ericaceous) dwarf shrub heath 0.1 0.4 0.4 6.4 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.4 1.3 1.9 22.4 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.5 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 1.4 Bog (grass/herb over deep peat) 0.0 0.1 0.3 17.7 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.3 0.7 0.1 0.2 Despoiled bare ground 0.1 0.1 0.0 0.0
38 Table 3.4. Areas of LCM2000 habitats within four landscape components for Lake District Agriculture Hilledge Grassmoor Heathermoor 88388 Area covered 68606 (83951) 8900 32561 Area covered within ESA boundary 48087 84177 8834 32116 Area covered within National Park boundary 45231 79858 8598 30901 Lake District National Park: less dominated by a single land cover class than other areas, but characterised by Pteridium (35% of the hill-edge area), with significant areas of acid and neutral grassland.
Fig. 3.8. Extent of hill-edge habitats in the Lake District National Park and adjacent areas. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
39 Table 3.5. Summary of the percentage of LCM2000 habitats within four landscape components for the North Pennine Dales. Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 4.1 2.7 0.6 0.5 Mixed broad leaved woodland 3.2 1.9 0.1 0.2 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 1.4 5.9 1.1 1.0 Felled conifers 0.0 0.0 0.1 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 5.7 0.0 0.0 0.0 Arable horticulture 5.3 0.2 0.0 0.1 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.6 0.0 0.0 0.0 Improved grassland (intensive) 42.6 1.4 0.2 0.1 Improved grassland (grass (hay/ silage cut)) 21.0 1.2 0.2 0.1 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.7 0.2 0.0 0.1 Neutral grass (grazed) 5.0 54.0 18.0 7.2 Calcareous (rough) 6.9 15.3 2.0 0.8 Calcareous (grazed) 1.8 0.5 0.1 0.0 Acid grass 0.2 4.6 32.1 5.8 Acid grass (rough) 0.0 0.1 0.1 0.1 Acid grass with Juncus 0.1 0.6 2.5 0.8 Acid grass with Nardus/Festuca/Molinia 0.1 4.4 37.9 7.4 Bracken 0.5 3.0 0.7 0.7 Dense (ericaceous) dwarf shrub heath 0.2 0.5 0.8 27.5 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.2 0.7 1.6 19.2 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 9.7 Bog (grass/shrub over deep peat) 0.0 0.0 0.1 4.6 Bog (grass/herb over deep peat) 0.0 0.1 0.6 10.7 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 2.3 Semi-natural bare ground 0.4 2.7 1.1 1.2 Despoiled bare ground 0.0 0.0 0.0 0.0
40 Table 3.5 (cont’d) Areas of LCM2000 habitats within four landscape components for the North Pennine Dales. Agriculture hilledge Grassmoor Heathermoor 158444 Area covered 209775 (148425) 11023 176426 Area covered within ESA boundary 27189 22650 526 2853 Area covered within National Park boundary 36149 69089 3902 50703 North Pennines: dominated by grassland (particularly neutral), although extensive enclosed allotment land which should be classified as hill-edge is dominated by acidic communities (ADAS, 1996a). Some conifer plantations and broad-leaved woodland occur, particularly Fraxinus excelsior communities (Drewitt, 1991).
Fig. 3.9. Extent of hill-edge habitats in the Northern Pennines. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
41 Table 3.6. Summary of the percentage of LCM2000 habitats within four landscape components for North York Moors Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 5.6 11.3 6.4 0.5 Mixed broad leaved woodland 3.4 8.9 2.3 0.6 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 2.3 37.9 26.7 4.1 Felled conifers 0.0 0.4 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 13.7 0.2 0.0 0.0 Arable horticulture 30.0 2.5 3.8 0.4 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 29.7 3.3 2.0 0.2 Improved grassland (grass (hay/ silage cut)) 4.4 0.8 0.9 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 1.4 1.1 0.0 0.1 Neutral grass (rough) 1.2 1.7 1.2 0.1 Neutral grass (grazed) 0.8 8.9 10.2 2.7 Calcareous (rough) 1.8 6.5 5.2 1.1 Calcareous (grazed) 4.1 3.1 0.7 0.0 Acid grass 0.1 1.1 1.4 0.8 Acid grass (rough) 0.3 0.7 0.2 0.1 Acid grass with Juncus 0.1 0.7 0.9 0.3 Acid grass with Nardus/Festuca/Molinia 0.0 0.7 2.1 0.8 Bracken 0.3 4.7 15.3 2.1 Dense (ericaceous) dwarf shrub heath 0.0 1.2 5.6 46.5 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.2 3.3 12.2 26.4 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 7.6 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 3.2 Bog (grass/herb over deep peat) 0.0 0.0 0.2 0.4 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.5 0.9 2.5 1.9 Despoiled bare ground 0.0 0.0 0.0 0.0
42 Table 3.6 (cont’d). Areas of LCM2000 habitats within four landscape components for North York Moors Agriculture Hilledge Grassmoor Heathermoor 24537 Area covered 97435 (14545) 980 45617 Area covered within National Park boundary 58055 23860 972 45538 North York Moors: the hill-edge is typically a narrow band between improved grass and moorland (Sinclair, 1983). Coniferous plantation represents the greatest area with significant areas of semi-natural woodland and a range of grassland types. Pteridium that dominates 28% of the moorland (Whitehead & Digby, 1997) is estimated at only 5% of the hill-edge
Fig. 3.10. Extent of hill-edge habitats in the North York Moors National Park and adjacent areas. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage.
43 Table 3.7. Summary of the percentage of LCM2000 habitats within four landscape components for Forest of Bowland. Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 1.9 2.1 0.7 0.3 Mixed broad leaved woodland 6.3 5.4 0.9 0.3 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 0.4 7.5 2.2 1.5 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 1.9 0.0 0.0 0.0 Arable horticulture 4.1 0.2 0.0 0.1 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 49.5 1.0 0.7 0.0 Improved grassland (grass (hay/ silage cut)) 24.3 0.7 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.7 0.8 0.0 0.1 Neutral grass (grazed) 3.3 57.6 18.6 6.5 Calcareous (rough) 3.6 8.8 2.9 0.5 Calcareous (grazed) 3.5 1.2 0.0 0.0 Acid grass 0.1 6.5 48.9 11.3 Acid grass (rough) 0.1 0.2 0.0 0.0 Acid grass with Juncus 0.1 1.3 3.9 0.9 Acid grass with Nardus/Festuca/Molinia 0.1 3.5 13.6 2.0 Bracken 0.0 1.5 2.4 0.5 Dense (ericaceous) dwarf shrub heath 0.0 0.4 1.8 49.5 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.0 0.4 1.5 7.7 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 9.8 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 3.5 Bog (grass/herb over deep peat) 0.0 0.1 0.4 4.0 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.5 Semi-natural bare ground 0.1 0.9 1.6 1.1 Despoiled bare ground 0.0 0.0 0.0 0.0
44 Table 3.7 (cont’d). Areas of LCM2000 habitats within four landscape components for Forest of Bowland. Agriculture Hilledge Grassmoor Heathermoor 15883 Area 51101 (14625) 839 17428 Forest of Bowland: dominated by grassland, largely classified as neutral, with some coniferous plantation and semi-natural woodland.
Fig. 3.11. Extent of hill-edge habitats in the Forest of Bowland Area of Outstanding Natural Beauty. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Black line = limit to model coverage.
45 Table 3.8. Summary of the percentage of LCM2000 habitats within four landscape components for South Pennines natural area. Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 7.7 7.7 1.8 1.1 Mixed broad leaved woodland 6.1 6.5 1.3 0.8 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.1 0.1 0.1 Mature conifers 1.0 3.7 3.7 1.7 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 2.7 0.2 0.0 0.0 Arable horticulture 6.0 0.6 0.0 0.1 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 39.9 2.3 0.5 0.3 Improved grassland (grass (hay/ silage cut)) 13.9 1.0 0.1 0.1 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.3 0.1 0.0 0.0 Neutral grass (rough) 3.4 3.8 1.1 0.4 Neutral grass (grazed) 8.3 39.5 19.3 5.5 Calcareous (rough) 3.9 12.1 0.6 0.4 Calcareous (grazed) 3.8 2.6 0.4 0.1 Acid grass 0.5 7.1 48.0 11.8 Acid grass (rough) 0.2 0.8 1.4 0.4 Acid grass with Juncus 0.3 1.2 1.0 1.0 Acid grass with Nardus/Festuca/Molinia 0.1 1.3 10.5 3.0 Bracken 0.5 3.8 2.3 0.8 Dense (ericaceous) dwarf shrub heath 0.2 1.1 2.0 25.1 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.1 1.1 2.7 13.4 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.1 9.9 Bog (grass/shrub over deep peat) 0.0 0.0 0.1 5.9 Bog (grass/herb over deep peat) 0.0 0.2 0.4 13.9 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 1.4 Semi-natural bare ground 0.9 3.3 2.6 3.2 Despoiled bare ground 0.1 0.1 0.0 0.0
46 Table 3.8 (cont’d). Areas of LCM2000 habitats within four landscape components for South Pennines natural area. Agriculture Hilledge Grassmoor Heathermoor Area of hilledge across south pennines 88663 133250 (85151) 4169 75246 Area within National Park 25489 34255 2329 42935
Fig. 3.12. Extent of hill-edge habitats in the South Pennines. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
47 Table 3.9. Summary of the percentage of LCM2000 habitats within four landscape components for North Peak ESA. Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 8.1 11.2 3.5 1.5 Mixed broad leaved woodland 6.5 8.2 1.1 1.2 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.2 0.3 0.1 Mature conifers 1.4 5.2 5.5 1.9 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 2.5 0.2 0.0 0.0 Arable horticulture 8.8 0.7 0.1 0.1 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 39.5 2.8 0.5 0.3 Improved grassland (grass (hay/ silage cut)) 10.1 1.3 0.1 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.5 0.1 0.1 0.0 Neutral grass (rough) 3.5 3.9 0.1 0.2 Neutral grass (grazed) 8.1 32.1 19.1 4.7 Calcareous (rough) 3.3 9.6 0.4 0.3 Calcareous (grazed) 4.3 3.5 0.0 0.0 Acid grass 0.6 7.9 49.1 12.1 Acid grass (rough) 0.3 1.3 0.3 0.2 Acid grass with Juncus 0.2 1.5 1.4 0.9 Acid grass with Nardus/Festuca/Molinia 0.2 1.7 5.7 2.7 Bracken 0.5 2.6 2.7 0.6 Dense (ericaceous) dwarf shrub heath 0.3 1.9 2.5 26.8 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.1 1.2 2.7 11.4 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.1 10.0 Bog (grass/shrub over deep peat) 0.0 0.0 0.2 6.8 Bog (grass/herb over deep peat) 0.0 0.2 0.8 14.0 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.8 Semi-natural bare ground 1.0 2.4 4.0 3.3 Despoiled bare ground 0.1 0.0 0.0 0.0
48 Table 3.9 (cont’d). Areas of LCM2000 habitats within four landscape components for North Peak ESA. Agriculture Hilledge Grassmoor Heathermoor Area covered 36096 54855 (34052) 1913 46839 Area covered within ESA boundary 40421 10450 1346 37808
Fig. 3.13. Extent of hill-edge habitats in the North Peak Environmentally Sensitive Area. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
49 Table 3.10. Summary of the percentage of LCM2000 habitats within four landscape components for South West Peak ESA Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 9.8 5.3 0.1 0.6 Mixed broad leaved woodland 0.0 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 0.8 2.5 2.6 3.2 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 2.9 0.1 0.0 0.0 Arable horticulture 2.8 0.2 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 47.2 0.8 0.1 0.2 Improved grassland (grass (hay/ silage cut)) 20.8 0.5 0.0 0.1 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.3 0.0 0.0 0.0 Neutral grass (rough) 2.6 4.2 3.9 1.9 Neutral grass (grazed) 2.8 31.2 7.7 4.1 Calcareous (rough) 4.1 26.9 0.9 1.4 Calcareous (grazed) 3.2 2.1 1.6 0.4 Acid grass 0.3 8.9 63.4 20.7 Acid grass (rough) 0.2 1.0 4.5 3.4 Acid grass with Juncus 0.0 0.0 0.0 0.0 Acid grass with Nardus/Festuca/Molinia 0.0 0.1 8.4 4.9 Bracken 1.5 10.1 3.2 3.1 Dense (ericaceous) dwarf shrub heath 0.0 0.2 0.6 33.2 Gorse 0.1 0.6 2.3 18.2 Open dwarf shrub heath 0.0 0.0 0.0 1.4 Swamp 0.0 0.0 0.0 0.4 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/herb over deep peat) 0.0 0.0 0.0 1.0 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.1 4.8 0.8 1.9 Despoiled bare ground 0.3 0.5 0.0 0.0
50 Table 3.10 (cont’d). Areas of LCM2000 habitats within four landscape components for South West Peak ESA Agriculture Hilledge Grassmoor Heathermoor Area covered 22483 18148 (21908) 1032 6332 Area covered within ESA boundary 7551 13283 986 6206
Fig. 3.14. Extent of hill-edge habitats in the South-west Peak Environmentally Sensitive Area. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
51 Table 3.11. Summary of the percentage of LCM2000 habitats within four landscape components for Shropshire hills. Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 8.2 8.2 0.2 0.6 Mixed broad leaved woodland 0.0 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 1.9 10.7 3.5 2.5 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.1 0.0 0.0 Arable cereals 21.1 0.1 0.0 0.0 Arable horticulture 9.6 0.3 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 38.4 3.1 0.3 0.1 Improved grassland (grass (hay/ silage 13.3 0.4 0.0 0.0 cut)) Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.2 0.5 0.0 0.0 Neutral grass (rough) 0.2 0.9 0.1 0.2 Neutral grass (grazed) 0.4 14.7 4.8 2.3 Calcareous (rough) 2.2 18.5 1.7 3.2 Calcareous (grazed) 2.8 1.7 0.9 0.1 Acid grass 0.5 22.7 77.7 29.6 Acid grass (rough) 0.3 1.6 1.2 2.3 Acid grass with Juncus 0.0 0.0 0.0 0.0 Acid grass with Nardus/Festuca/Molinia 0.0 0.5 0.5 3.0 Bracken 0.3 12.0 6.3 8.9 Dense (ericaceous) dwarf shrub heath 0.0 0.3 0.5 24.0 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.1 2.2 2.0 20.9 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/herb over deep peat) 0.0 0.0 0.0 0.0 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.0 1.5 0.3 2.5 Despoiled bare ground 0.3 0.0 0.0 0.0
52 Table 3.11 (cont’d). Areas of LCM2000 habitats within four landscape components for Shropshire hills. Heather Agriculture Hilledge Grassmoor moor Area covered 21642 6561 (5812) 915 3687 Area covered within ESA boundary 8403 6292 913 3684 Notes Shropshire Hills: dominated by grassland, largely acidic but with significant areas of both neutral and calcareous communities. Pteridium, conifer plantations and broad- leaved woodland each account for around 10% of the hill-edge.
Fig. 3.15. Extent of hill-edge habitats in the Shropshire Hills Environmentally Sensitive Area. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
53 Table 3.12. Summary of the percentage of LCM2000 habitats within four landscape components for Snowdonia Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 13.1 10.8 0.6 0.8 Mixed broad leaved woodland 0.0 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 1.9 18.3 3.1 4.3 Felled conifers 0.1 1.0 0.3 0.7 New conifer plantation 0.3 1.3 0.2 0.3 Arable cereals 1.1 0.0 0.0 0.0 Arable horticulture 3.2 0.3 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 64.2 2.5 0.0 0.1 Improved grassland (grass (hay/ silage cut)) 1.3 0.1 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.1 0.0 0.0 0.0 Neutral grass (rough) 2.5 2.3 0.0 0.1 Neutral grass (grazed) 1.3 18.2 1.1 2.1 Calcareous (rough) 2.8 10.3 0.6 0.7 Calcareous (grazed) 2.8 1.2 0.0 0.0 Acid grass 1.7 17.1 58.5 20.5 Acid grass (rough) 2.1 3.2 1.8 0.8 Acid grass with Juncus 0.4 0.4 0.2 0.1 Acid grass with Nardus/Festuca/Molinia 0.1 7.9 31.2 19.6 Bracken 0.1 1.0 0.2 0.4 Dense (ericaceous) dwarf shrub heath 0.1 0.8 0.6 32.6 Gorse 0.0 0.0 0.5 0.1 Open dwarf shrub heath 0.1 0.5 0.0 13.3 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.1 0.3 0.0 0.2 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.4 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.2 Bog (grass/herb over deep peat) 0.0 0.0 0.0 0.7 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.4 1.9 0.9 1.8 Despoiled bare ground 0.2 0.6 0.1 0.1
54 Table 3.12 (cont’d). Areas of LCM2000 habitats within four landscape components for Snowdonia Agriculture Hilledge Grassmoor Heathermoor 155745 Area covered 85781 (123283) 39254 99769 Area covered within National Park boundary 24501 73444 21616 58170
Fig. 3.16. Extent of hill-edge habitats in the Snowdonia National Park and adjacent areas. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage.
55 Table 3.13. Summary of the percentage of LCM2000 habitats within four landscape components for Mid-Wales ESAs Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 10.6 4.0 0.1 0.3 Mixed broad leaved woodland 0.0 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 1.8 18.8 1.8 3.2 Felled conifers 0.0 0.7 0.3 0.3 New conifer plantation 0.1 0.8 0.1 0.1 Arable cereals 1.3 0.1 0.0 0.0 Arable horticulture 2.6 0.4 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 70.3 2.5 0.1 0.1 Improved grassland (grass (hay/ silage cut)) 0.3 0.0 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.7 0.4 0.0 0.0 Neutral grass (grazed) 0.7 14.7 1.9 5.5 Calcareous (rough) 3.0 20.6 1.7 4.6 Calcareous (grazed) 3.8 1.0 0.0 0.0 Acid grass 1.7 19.1 65.0 34.8 Acid grass (rough) 1.2 1.2 0.4 0.3 Acid grass with Juncus 0.0 0.0 0.0 0.0 Acid grass with Nardus/Festuca/Molinia 0.4 4.6 25.0 7.5 Bracken 0.6 5.9 1.4 3.2 Dense (ericaceous) dwarf shrub heath 0.2 1.0 0.7 12.5 Gorse 0.0 0.1 0.0 0.7 Open dwarf shrub heath 0.2 1.2 0.8 21.2 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.1 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.2 Bog (grass/herb over deep peat) 0.0 0.0 0.0 3.2 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.5 2.6 0.6 1.9 Despoiled bare ground 0.1 0.3 0.0 0.1
56 Table 3.13 (cont’d). Areas of LCM2000 habitats within four landscape components for Mid-Wales ESAs Agriculture Hilledge Grassmoor Heathermoor 101710 Area 86224 (80751) 27045 51212
Fig. 3.17. Extent of hill-edge habitats in Mid-Wales Environmentally Sensitive Areas (Cambrian Mountains, Radnor & Clun) and adjacent areas. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
57 Table 3.14. Summary of the percentage of LCM2000 habitats within four landscape components for Clun ESA. Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 9.0 5.3 0.2 0.0 Mixed broad leaved woodland 0.0 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 0.5 3.8 0.3 2.7 Felled conifers 0.0 0.2 0.4 0.5 New conifer plantation 3.2 2.3 0.3 0.0 Arable cereals 0.0 0.0 0.0 0.0 Arable horticulture 4.6 0.8 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 50.6 0.8 0.0 0.0 Improved grassland (grass (hay/ silage cut)) 11.3 0.1 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.0 0.3 0.0 0.0 Neutral grass (grazed) 1.8 26.1 0.6 4.6 Calcareous (rough) 12.3 41.2 4.5 4.0 Calcareous (grazed) 1.7 0.9 0.0 0.0 Acid grass 2.8 9.0 80.1 56.0 Acid grass (rough) 0.0 0.4 0.0 0.0 Acid grass with Juncus 0.0 0.0 0.0 0.0 Acid grass with Nardus/Festuca/Molinia 0.0 3.5 9.8 4.4 Bracken 0.6 1.5 0.2 1.5 Dense (ericaceous) dwarf shrub heath 0.1 0.4 1.7 16.8 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.2 0.5 0.8 4.3 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/herb over deep peat) 0.0 0.0 0.0 0.0 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.8 3.0 1.0 5.3 Despoiled bare ground 0.5 0.0 0.0 0.0
58 Table 3.14 (cont’d). Areas of LCM2000 habitats within four landscape components for Clun ESA. Agriculture Hilledge Grassmoor Heathermoor Area within ESA boundary 685 4681 (4382) 357 193
59 Table 3.15. Summary of the percentage of LCM2000 habitats within four landscape components for Radnor Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 8.5 2.6 0.1 0.3 Mixed broad leaved woodland 0.0 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 1.2 8.9 3.3 2.9 Felled conifers 0.0 0.1 0.4 0.4 New conifer plantation 0.1 0.9 0.1 0.1 Arable cereals 2.6 0.1 0.0 0.0 Arable horticulture 3.8 0.3 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 70.4 2.1 0.2 0.2 Improved grassland (grass (hay/ silage cut)) 0.5 0.0 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.2 0.3 0.1 0.1 Neutral grass (grazed) 0.4 19.0 4.5 5.1 Calcareous (rough) 4.8 35.4 3.5 6.0 Calcareous (grazed) 4.5 1.4 0.0 0.1 Acid grass 0.3 12.9 75.9 32.7 Acid grass (rough) 0.3 0.4 0.4 0.4 Acid grass with Juncus 0.0 0.0 0.0 0.0 Acid grass with Nardus/Festuca/Molinia 0.5 4.1 5.0 4.0 Bracken 0.7 5.2 2.3 4.0 Dense (ericaceous) dwarf shrub heath 0.3 1.4 1.8 23.6 Gorse 0.1 0.1 0.0 0.2 Open dwarf shrub heath 0.3 1.2 1.3 17.4 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/herb over deep peat) 0.0 0.0 0.0 0.0 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.5 3.4 1.1 2.6 Despoiled bare ground 0.1 0.1 0.0 0.1
60 Table 3.15 (cont’d). Areas of LCM2000 habitats within four landscape components for Radnor Agriculture Hilledge Grassmoor Heathermoor 32723 Area within ESA boundary 36888 (29429) 4358 13472 Radnor: grassland (largely acidic) and dwarf shrub heath account for nearly 90% of the hill-edge area with some Pteridium.
61 Table 3.16. Summary of the percentage of LCM2000 habitats within four landscape components for Cambrian Mountains ESA Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 10.1 4.3 0.1 0.2 Mixed broad leaved woodland 0.0 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 2.6 29.1 1.1 3.2 Felled conifers 0.1 1.4 0.3 0.4 New conifer plantation 0.1 0.7 0.1 0.1 Arable cereals 0.4 0.0 0.0 0.0 Arable horticulture 1.9 0.5 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 69.6 2.6 0.0 0.1 Improved grassland (grass (hay/ silage cut)) 0.0 0.0 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.5 0.2 0.0 0.0 Neutral grass (grazed) 1.2 10.2 0.7 3.7 Calcareous (rough) 1.2 3.2 0.2 0.5 Calcareous (grazed) 1.7 0.4 0.0 0.0 Acid grass 5.6 27.8 63.1 40.7 Acid grass (rough) 2.5 1.6 0.4 0.2 Acid grass with Juncus 0.2 0.0 0.0 0.0 Acid grass with Nardus/Festuca/Molinia 0.4 5.9 31.7 11.9 Bracken 0.5 7.6 1.0 3.1 Dense (ericaceous) dwarf shrub heath 0.2 0.6 0.3 9.0 Gorse 0.1 0.1 0.0 1.2 Open dwarf shrub heath 0.3 1.1 0.5 17.0 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.2 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.3 Bog (grass/herb over deep peat) 0.0 0.0 0.0 6.3 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.8 2.1 0.4 1.6 Despoiled bare ground 0.0 0.5 0.1 0.1
62 Table 3.16 (Cont’d). Areas of LCM2000 habitats within four landscape components for Cambrian Mountains ESA Agriculture Hilledge Grassmoor Heathermoor 45162 Area within ESA boundary 18987 (31094) 20083 24499 Cambrian ESA: dominated by acid grassland and coniferous plantations with some Pteridium and broad-leaved woodland.
63 Table 3.17. Summary of the percentage of LCM2000 habitats within four landscape components for Brecon Beacons Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 13.8 8.9 0.4 0.4 Mixed broad leaved woodland 0.1 0.0 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 1.7 21.8 8.0 3.7 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 3.0 0.3 0.1 0.0 Arable horticulture 6.2 0.7 0.1 0.1 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 59.8 3.3 0.2 0.1 Improved grassland (grass (hay/ silage cut)) 2.5 0.0 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.2 0.0 0.0 0.0 Neutral grass (rough) 2.8 3.4 0.3 0.2 Neutral grass (grazed) 0.8 20.5 13.5 14.1 Calcareous (rough) 0.7 5.7 3.2 2.3 Calcareous (grazed) 4.1 1.7 0.1 0.0 Acid grass 0.5 9.4 42.4 15.6 Acid grass (rough) 1.3 2.2 0.6 0.3 Acid grass with Juncus 0.0 0.0 0.0 0.0 Acid grass with Nardus/Festuca/Molinia 0.4 4.6 16.5 3.5 Bracken 0.6 9.1 4.9 4.5 Dense (ericaceous) dwarf shrub heath 0.2 1.4 1.8 14.7 Gorse 0.0 0.1 0.2 0.9 Open dwarf shrub heath 0.3 2.4 3.6 33.7 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.1 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.4 Bog (grass/herb over deep peat) 0.0 0.1 0.4 1.4 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.0 Semi-natural bare ground 0.4 3.6 3.5 3.5 Despoiled bare ground 0.6 0.8 0.3 0.3
64 Table 3.17 (Cont’d). Areas of LCM2000 habitats within four landscape components for Brecon Beacons Agriculture Hilledge Grassmoor Heathermoor 71251 Area covered 108489 (55011) 7113 57557 Area covered within National Park boundary 43682 34586 3711 34566
Fig. 3.18. Extent of hill-edge habitats in the Brecon Beacons National Park and adjacent areas. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage.
65 Table 3.18. Summary of the percentage of LCM2000 habitats within four landscape components for Exmoor Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 9.5 25.2 2.9 6.5 Mixed broad leaved woodland 2.1 10.4 2.6 3.5 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 0.0 0.0 0.0 0.0 Mature conifers 1.6 12.2 2.1 0.2 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 3.8 0.1 0.0 0.0 Arable horticulture 5.6 1.5 0.0 0.0 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 69.0 2.9 0.3 0.1 Improved grassland (grass (hay/ silage cut)) 0.0 0.0 0.0 0.0 Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.7 1.0 0.0 0.0 Neutral grass (grazed) 1.6 14.8 5.5 4.0 Calcareous (rough) 0.8 0.8 0.2 0.1 Calcareous (grazed) 0.4 0.0 0.0 0.0 Acid grass 1.9 12.5 31.9 17.4 Acid grass (rough) 0.6 0.5 0.0 0.1 Acid grass with Juncus 1.5 5.1 0.3 0.2 Acid grass with Nardus/Festuca/Molinia 0.4 9.9 52.4 16.5 Bracken 0.0 0.0 0.0 0.0 Dense (ericaceous) dwarf shrub heath 0.2 1.0 0.5 25.4 Gorse 0.1 0.3 0.0 0.0 Open dwarf shrub heath 0.0 1.3 1.3 24.0 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.0 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 0.1 Bog (grass/herb over deep peat) 0.0 0.2 0.0 1.7 Bog (undifferentiated over deep peat) 0.0 0.0 0.0 0.1 Semi-natural bare ground 0.1 0.2 0.0 0.0 Despoiled bare ground 0.0 0.0 0.0 0.0
66 Table 3.18 (cont’d). Areas of LCM2000 habitats within four landscape components for Exmoor Agriculture Hilledge Grassmoor Heathermoor Area covered 29580 9774 (8546) 1214 6408 Area covered within ESA boundary 28075 9743 1214 6408 Area covered within National Park boundary 27338 9695 1214 6408
Exmoor: dominated by acid/neutral grassland, but with an unusually high proportion of broad-leaved woodland (25%) and scrub (10%). Conifer plantations are also important. x 450 ha block of grass moor – more compact shape but with a large fragment of heather moor in the centre probably does not qualify as true extensive grass moor x Virtually all of the moorland and hill-edge falls within ESA or NP boundaries x 38% of heather moorland landscape component composed of grasses
Fig. 3.19. Extent of hill-edge habitats in the Exmoor National Park and adjacent areas. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
67 Table 3.19. Summary of the percentage of LCM2000 habitats within four landscape components for Dartmoor Agriculture Hilledge Grassmoor Heathermoor Deciduous woodland 13.3 16.5 0.5 0.5 Mixed broad leaved woodland 0.0 0.1 0.0 0.0 Open Birch woodland 0.0 0.0 0.0 0.0 Scrub 1.8 9.6 1.5 1.7 Mature conifers 1.0 8.4 0.9 0.3 Felled conifers 0.0 0.0 0.0 0.0 New conifer plantation 0.0 0.0 0.0 0.0 Arable cereals 8.5 0.2 0.0 0.0 Arable horticulture 8.3 1.0 0.1 0.1 Orchard 0.0 0.0 0.0 0.0 Arable grass ley 0.0 0.0 0.0 0.0 Setaside (bare) 0.0 0.0 0.0 0.0 Setaside (undifferentiated) 0.0 0.0 0.0 0.0 Improved grassland (intensive) 59.4 2.4 0.0 0.0 Improved grassland (grass (hay/ silage 0.0 0.0 0.0 0.0 cut)) Improved grassland (grazing marsh) 0.0 0.0 0.0 0.0 Setaside grass 0.0 0.0 0.0 0.0 Neutral grass (rough) 0.1 0.1 0.0 0.2 Neutral grass (grazed) 0.7 19.9 4.2 5.4 Calcareous (rough) 1.3 2.4 0.0 0.0 Calcareous (grazed) 2.3 0.4 0.0 0.0 Acid grass 1.1 15.4 29.5 9.1 Acid grass (rough) 0.7 0.7 0.5 0.1 Acid grass with Juncus 0.7 1.8 0.2 0.1 Acid grass with 0.4 14.9 60.9 22.5 Nardus/Festuca/Molinia Bracken 0.0 0.0 0.0 0.0 Dense (ericaceous) dwarf shrub heath 0.1 0.5 0.4 2.9 Gorse 0.0 0.0 0.0 0.0 Open dwarf shrub heath 0.0 1.1 1.3 33.5 Swamp 0.0 0.0 0.0 0.0 Fen / marsh 0.0 0.0 0.0 0.0 Willow fen 0.0 0.0 0.0 0.0 Bog (shrub over deep peat) 0.0 0.0 0.0 0.1 Bog (grass/shrub over deep peat) 0.0 0.0 0.0 6.0 Bog (grass/herb over deep peat) 0.0 0.1 0.0 6.7 Bog (undifferentiated over deep peat) 0.0 0.0 0.1 10.7 Semi-natural bare ground 0.1 0.2 0.0 0.0 Despoiled bare ground 0.1 4.5 0.0 0.0
68 Table 3.19 (cont’d). Areas of LCM2000 habitats within four landscape components for Dartmoor Agriculture Hilledge Grassmoor Heathermoor Area covered 50607 22900 (20950) 4368 25783 Area covered within ESA 31551 22073 4367 25781 boundary Area covered within National 30190 20760 4365 25777 Park boundary
Dartmoor: dominated by acid/neutral grassland, with significant areas of broad- leaved woodland (17%) and scrub (10%). Conifer plantations are also important. x Almost all of the moorland landscape components within both ESA and NP boundaries. x 90% of hill-edge lies within the NP boundary too. x Proportion of grass moorland is low compared to other sites x Over 37% of heathermoorland component composed of grasses – high – fragmented though organised nature of ericaceous and bog habitats on the moor x Largest block of grass moor is only 494 ha and because of its limited size and convoluted shape should probably not qualify for the name – grass moorland. x Area of coniferous forest 1950 ha small in comparison with other areas and mostly concentrated around Fernworthy reservoir, Postbridge and Bellever
Fig. 3.20. Extent of hill-edge habitats in the Dartmoor National Park and adjacent areas. Purple = ericaceous moorland; pink = grass moorland, pale blue =hill-edge; dark green = conifer plantations. Blue line= National Park boundary. Black line = limit to model coverage. Red line = Environmentally Sensitive Area boundary.
69 VEGETATION
Summary
x This review aims to identify the major habitat types of the hill-edge, review what is known about the plant communities, and consider the factors causing changes in vegetation. x Rough and semi-natural grasslands were the most widespread habitats on the hill-edge in England and Wales. Most grassland was acidic. However, significant areas of calcareous grassland were recorded from the North Pennines, Bowland and the Shropshire Hills. Neutral grasslands were particularly important in the North Pennines, Bowland and Northumbria. Dwarf shrub heaths comprised a very minor component of the hill-edge nationally but were widespread in one area of Mid-Wales (Radnor). x Conifer plantations covered between 5-10% of the hill-edge in England and Wales. However, the percentage of the hill-edge covered by plantations varied considerably between regions and was particularly high (>29%) in Northumberland, and North York Moors National Parks and in the Cambrian Mountains ESA. Broad-leaved and mixed woodlands comprised 5-10% of the hill-edge in England and Wales but cover varied regionally and was high (>20%) in Dartmoor, Exmoor and the North York Moors. x Less than 5% of the hill-edge in England and Wales was covered by dense stands of bracken Pteridium aquilinum. x Grassland types occurring on the hill-edge include acid and calcareous unimproved rough grazings, semi-improved or semi-natural mesotrophic grasslands, wet grassland dominated by rushes and sometimes improved pasture or hay meadows interspersed with more typical hill-edge habitats. x Acid grassland is the most common hill-edge habitat. It is generally species-poor and dominated by Molinia carulea and Nardus stricta, though some areas are species rich, particularly for bryophytes and club-mosses. Semi-natural mesotrophic grasslands are rare, because they are readily improved, but a range of mesotrophic grasslands improved to varying degrees can occur on the hill-edge. Calcareous grasslands cover a much smaller area than acid grasslands, but are more species-rich and include many rare and uncommon species. x Rocky areas, e.g. rock outcrops, scree, tors and limestone pavements, may be botanically important for pioneer species but also form important refuges for species susceptible to grazing. Metalliferous communities occur on mining spoil in northern England and in some areas give rise to communities with high botanical interest. x A range of communities associated with wet areas on both acid and base-rich soils occur on the hill-edge. They may cover large areas or be restricted to local flushes, and often occur in mosaics with other communities. Wet acid grasslands tend to be species-poor with dominant species ranging from Molinia caerulea in dryer areas through Juncus spp. to sedges and Sphagnum mosses in the wettest areas. Base-rich flushes tend to support a wider range of species. x Bracken (Pteridium aquilinum) occurs over large areas, especially in the west of Britain, and is often the dominant species, representing an important vegetation type of the hill-edge. Because of the dense shade it produces, bracken stands are generally
70 species poor. At a local scale, bracken stands may be botanically valuable, and provide habitat for some bird and invertebrate species of conservation concern. x Dwarf shrub heath vegetation is generally typical of open moorland, but also found on the hill-edge. It is generally species-poor, though it can be very rich in bryophytes and lichens. x Scrub generally occurs in small and scattered fragments, many of which are not regenerating. It is an important habitat and an increase in scrub would bring conservation benefits. Juniper scrub has a particular conservation value, and occurs in scattered stands in England and Wales, particularly the north Pennines. x Ancient or semi-natural woodlands are widespread, but usually occur in small pockets in inaccessible areas. They often suffer from overgrazing and consequently suffer from lack of regeneration and an impoverished ground flora. In contrast, coniferous plantations often occupy large areas but are generally of little botanical interest. On base-poor and acidic soils, oak Quercus sp. is the dominant tree species of broadleaved woodland, whereas on base-rich soils, more species-rich ash (Fraxinus excelsior) – dominated woodlands occur. In wet areas, woodlands dominated by Salix cinerea, Betula pubescens, and Alnus glutinosa are found. x Walls are characteristic linear features of the uplands and can support a distinctive range of plant species, but many have been lost or damaged through increases in field size or neglect. x Management factors which can affect vegetation on the hill-edge include grazing (including species and density of stock and timing of grazing), improvement, reversion, and afforestation. x Grazing is necessary to maintain many semi-natural habitats, but heavy grazing is generally detrimental and can lead to the replacement of habitat mosaics with homogeneous vegetation dominated by relatively few species. Some species are intolerant of grazing and only persist where protected from it e.g. in rocky areas. x The replacement of cattle by sheep in recent decades coupled with high sheep stocking densities has led to a deterioration in the quality of vegetation with an increase in Nardus, Molinia and Juncus at the expense of more palatable grasses and dwarf shrubs. Timing and period of grazing are also important. Feeding of sheep in winter on heather (Calluna vulgaris) stands has resulted in the degradation of the heather to grass moor over large areas. x Agricultural improvement by reseeding, drainage, burning, cutting, fertilising, liming and herbicide use generally leads to loss of species and habitat diversity. Changing from hay to silage also reduces species diversity through earlier cutting and greater fertiliser use. x Improved grassland reverts back towards vegetation more typical of rough grazing at a rate depending on management, particularly drainage. Where management is not conducive to the retention of the introduced species, reversion can be rapid. Hay cutting followed by aftermath grazing produced the greatest species diversity in a reversion experiment. x Afforestation has probably had the greatest effect on hill-edge habitats over the last 50 years. Few plant species survive under mature conifers, though a more varied ground flora may persist in the rides. x Bracken has increased over the past few decades, and probably continues to do so in spite of efforts to control it. Factors potentially causing the expansion of bracken stands include burning, reduced cutting (for fuel, bedding etc), clear felling of woods, decreased intensity of farming, and the replacement of cattle by sheep.
71 x Grazing is the most important factor in the decline of juniperus. Light grazing in summer is beneficial, but grazing in winter or at high stocking rates is detrimental. Regeneration seems to depend on the availability of bare ground or short open swards where seedlings experience little competition. Establishment has often been most successful where grazing pressures have varied over time.
Scope of review
The aim of this review is to identify the major habitat types associated with hill-edge and their relative contribution to the hill-edge in different regions, using information derived largely from the GIS modelling study (see previous section). The review goes on to consider how much is known about the higher plant communities of the hill-edge habitats. The third section of the review considers the major short-term drivers of habitat change and their impacts on the composition of plant communities occurring in hill-edge habitats. Finally a summary of existing datasets, relevant to the hill-edge is presented.
Background
Few detailed studies of vegetation in the uplands of England and Wales have looked specifically at the hill-edge, although hill-edge habitats have been included in broader surveys of upland vegetation. As only a small proportion of published data is spatially referenced, it has been difficult to determine what information is relevant specifically to the hill-edge, given the widespread distribution of the habitats that make up the hill-edge.
The following review seeks to summarise information on habitats that occur at the hill-edge. Information on species that occur within each habitat on the hill-edge has been presented whenever possible but it has often been drawn from data collected from a relevant habitat at other sites rather than data collected from the hill-edge itself (Table 4.1).
A case study: the ffridd in Wales
Hill-edge habitats in Wales, particularly those of the ffridd (e.g. Walters Davies & Davis, 1973), are particularly well described by the Common Land surveys and by a series of studies of the birds and vegetation of ffriddland in Mid- and North-Wales, undertaken by the RSPB (Lovegrove & Bowman, undated; Hobson, 1985, Garnett, 1988) and others (Bates, 1992).
The common land surveys of Radnor, Montgomery, Carmarthenshire and Ceredigion (Penford et al., 1990, Francis et al., 1989, Penford et al., 1989, Francis et al., 1990) were carried out in the 1980s. They comprise one of the few published spatially referenced datasets on the vegetation of the hill-edge in England and Wales. These surveys were conducted at the Phase 1 level with some additional species notes and some NVC communities were identified. However, recording at the more detailed level was not consistent even within individual commons and descriptions frequently referred to more than one community. Nonetheless, by cross-referencing the survey maps with the maps from the GIS analysis of the hill-edge, the Phase 1 data give a good idea of the range of habitats that occur on the hill-edge and their relative frequency in central and southern Wales (Table 1).
72 Table 4.1. Sources of ground-survey data on the vegetation and plant species assemblages of hill-edge habitats in England and Wales. Type of survey information Area Phase 1 Phase 1a Phase 2 NVC Fixed Other quadrat monitoring Uplands England & Wales Quadrat survey (1) Northumberland NP 1992 1992 Juniper – 1973, 1994 Yorkshire Dales NP 1985-88 1985-88 Broad- (2) leaf woods only Pennine Dales ESA Part Part + covered covered by NP by NP survey survey North Pennines Moorland + some hill- edge (3) Lake District NP & ESA 1983-87 North York Moors NP 1987-90 Moorland (4) 1995-6 (5) Peak District NP; North N Peak & SW Peak ESA Moss (1913) Peak & SW Peak ESAs SW Peak – 1993-96 (7) ESAs (6) Wales 1987-199? Common Upland Vegetation (CCW); Land Survey (9) Common Surveys Land (8). Surveys (8) Exmoor NP Grassland survey(10) Dartmoor NP & ESA Hay meadows –baseline 1995 Notes: (1) Ecology of vegetation change in Upland Landscapes (Ball et al., 1981). Series of quadrats 1m2 to 5,000m2: all species recorded. Located by grid reference. From 16 upland parishes in Cheviots, N Pennines, S Pennines, Peak District, Lake District, N York Moors, Exmoor, Dartmoor, Snowdonia, Cambrian Mts, Radnor-Clun, Brecon Mountains. (2) Not digitised; (3) Undertaken by SNH for EN, concentrating on moorland but some hill-edge habitats listed; (4) Covers whole of park –raster image only; (5) NVC data for 'moorland' 1995-1996 accounting for about one third of the park. Generally surveyed down to the moorland wall, but extended into enclosure where the vegetation was considered to be 'moorland' and included steep sided gullies with bracken and woodland. Digitised by EN; (6) Digitised by DEFRA. (7) SW – ADAS permanent quadrat/stand data - sample of rough grazing 1993 and 1996. Plus less intensively managed permanent grass in 1994; (8) Common land surveys – data collated by Rural Surveys Research Unit (Univ of Wales, Aberystwyth) in 1989 for Countryside Commission (Francis et al., 1989, 1990; Penford et al., 1989, 1990). Maps presented, therefore it is possible to identify hill-edge habitats. Phase 1 with notes, some comments re NVC. Sites surveyed or data collated from existing SSSI data: No. 2 Carmarthenshire; No. 6 Montgomery – only a few sites relevant; No. 7 Ceredigion; No. 10 Radnor; (9) 1981 Upland Vegetation Survey for NCC (now held by CCW). Survey was largely restricted to moorland sites, but there is the occasional reference to the hill-edge. Vegetation types mapped with species notes. No. 9 Radnor Forest SSSI 1981; No. 10 Gwaunceste-Glascwm- Rhulen Hill & Beacon Hill. (10) ENP grassland survey (Joyner, 1992) Exmoor National Park Butcher B, Stewart A. 1990. Grassland in the Exmoor National Park – report of survey 1990 (Unpublished Report by Somerset Trust for Nature Conservation).
Unimproved acidic grassland was the most common habitat recorded and apparently covered the greatest proportion of the hill-edge. Marshy grassland, acidic flushes and continuous/scattered Pteridium aquilinum were the other most frequently recorded habitats, although acidic flushes were very localised and represented a much smaller land area than
73 other habitats. Scattered scrub and grass/dwarf shrub heath mosaic were also fairly common. A wide range of other habitats including broad-leaved woodland, semi-improved grasslands, various rocky areas and bogs were recorded occasionally (Table 4.2).
Table 4.2. Frequency of recording Phase 1 habitats in the hill-edge in common land surveys (n = 100) of Radnor, Ceredigion, Carmarthenshire and Montgomery. (Constancy values are as follows: I = 1-10; II = 11-20; III = 21-30; IV = 31-40; V = 41-50; VI = 51-60). Habitat Constancy Description A11 I Broadleaved Woodland A111 I Broadleaved Semi-natural Woodland A12 I Coniferous woodland A122 I Coniferous Plantation A22 II Scattered Scrub A21 I Dense Scrub A3 I Parkland and scattered trees A4 I Recently felled woodland B11 VI Unimproved Acidic Grassland B111 I Acidic Unimproved Grassland – upland B12 I Semi-improved Acidic Grassland B22 I Semi-Improved Neutral Grassland B31 I Unimproved calcareous Grassland B4 I Improved/reseeded Grassland B5 IV Marshy Grassland C11 III Continuous Bracken C12 II Scattered Bracken D1 I Dry dwarf shrub heath D11 I Acidic Dry Dwarf Shrub Heath D2 I Wet Dwarf Shrub Heath D5 II Dry heath/ acidic grass mosaic D6 I Wet heath/ acidic grass mosaic E11 I Blanket bog E13 I Lowland Raised Bog E14 I Valley bog E21 III Acidic Flush F1 I Swamp and Fen I1 I Natural Rock exposure I11 I Inland cliff I12 I Scree I13 I Limestone pavement I21 I Quarry J1 I Cultivated land
Dominant and common species for the most common habitat types have been identified (Table 4.3), although it must be noted that these are by no means comprehensive because of the way the data was collected. Also, this Phase 1 data was not fully spatially referenced and that the GIS exercise is a large-scale interpretation of hill-edge. These data are therefore only a guide to the species composition of hill-edge habitats. Furthermore, the species lists do not reflect the diversity of individual communities, since many different communities may be classed under each habitat type. Acid grasslands were generally relatively species poor, whereas marshy grasslands were highly variable ranging from species poor to very diverse. Acidic flushes were often species rich and also quite variable. Species lists for Pteridium stands were rarely recorded, but Agrostis capillaris and Festuca ovina were apparently the most common understorey species. A range of tree and scrub species was recorded, with Quercus spp. the most common dominant of woodlands often with a ground layer of
74 Pteridium and Vaccinium myrtillus. Bog communities were dominated by species of waterlogged areas such as Eriophorum vaginatum, Trichophorum cespitosum and Sphagnum spp.. Rocky outcrops and screes were important for a range of bryophytes and ferns and for other species with low resistance to grazing pressure.
In a study of ffridd in central Wales, undertaken by the RSPB (Hobson, I985), five characteristic types of ffridd were recognised as follows: Pteridium interspersed with Ulex spp. patches 55% Semi-natural grass 10% Calluna/Vaccinium heath 19% Improved grass 9% Ulex spp. Scrub 6%
Bates (1992) surveyed four areas of ffridd in North Wales and assigned stands to NVC communities, although a species list was only produced for two species-rich wet flushes. Six main habitat types were recorded: Main Community Sub-community U4 Festuca ovina – Agrostis capillaris – Galium saxatile a, b, d, e U5 Nardus stricta – Galium saxatile d U20 Pteridium aquilinum – Galium saxatile a H8 Calluna vulgaris – Ulex gallii e H12 Calluna vulgaris – Vaccinium myrtillus c M25 Molinia caerulea – Potentilla erecta b
Pteridium was the most common habitat recorded in an earlier study of the ffridd in mid Wales between 1975 and 1978 (Lovegrove & Bowman, undated). Pteridium was the dominant vegetation on 10 of the 13 study sites, usually with an Agrostis/Festuca understorey, and represented over 70% of the area on the four largest sites. Wetter areas were dominated by Juncus effusus. Woodland fragments were represented only by scattered trees, largely Quercus petraea, Fraxinus excelsior and Alnus glutinosa. Derelict field boundaries were delineated by scattered Crataegus monogyna and Sorbus aucuparia and scree slopes occurred locally.
In the most wide ranging of the RSPB studies, Garnett (1988) compared ordinations of ffridd vegetation with selected environmental factors. Pteridium and Ulex spp. were associated with lower altitudes (< 250 m) and dry conditions, whereas semi-natural grasslands were more commonly found above 350 m and were negatively associated with dryness. This ordination excluded wet habitats such as pastures dominated by Juncus spp. (Garnett, 1988). Tree cover in the ffridd zone is very variable; Hobson (1985) reported between 0 and 70% of the area was scattered with trees (mean of 7 trees ha-1). The extent of hill-edge habitats depends on management and they may be squeezed between agricultural improvement below and the conservation of moorland above. Important factors that damage or change the character of the hill-edge include afforestation, agricultural improvement (reseeding, application of herbicides, fertiliser and lime), burning and overgrazing. These factors and their effects are considered at greater length in subsequent sections.
75 Table 4.3. Dominant (bold) and frequent or locally abundant species identified in the most common habitats of the hill-edge recorded in common land surveys. B11 B5 C11/C12 E21 Juncus squarrosus Juncus acutiflorus Pteridium aquilinum Juncus effusus Nardus stricta Juncus effuses Agrostis capillaris Molinia caerulea Agrostis capillaries Molinia caerulea Campanula rotundifolia Carex viridula ssp. oedocarpa Aira praecox Nardus stricta Deschampsia flexuosa Carex panicea Blechnum spicant Calluna vulgaris Festuca ovina Carex rostrata Campanula rotundifolia Carex binervis Galium saxatile Drosera rotundifolia Carex binervis Carex echinata Oxalis acetosella Eriophorum angustifolium Deschampsia flexuosa Carex panicea Sorbus aucuparia Galium palustre Festuca ovina Cirsium palustre Ulex spp. Juncus acutiflorus Galium saxatile Deschampsia cespitosa Narthecium ossifragum Juncus effuses Deschampsia flexuosa Polytrichum commune Luzula multiflora Erica tetralix Sphagnum papillosum Polytrichum commune Eriophorum vaginatum Sphagnum recurvum Potentilla erecta Lotus pedunculatus Stellaria uliginosa Rumex acetosella Lychnis flos-cuculi Vaccinium oxycoccos Vaccinium myrtillus Polygala serpyllifolia Viola palustris Polytrichum commune Sphagnum papillosum Sphagnum recurvum
76 Table 4.3. cont. A21/A22 D5 A11/A111 E11 I11/I12 Alnus glutinosa Nardus stricta Quercus petraea Eriophorum vaginatum Asplenium adiantum-nigrum Betula pubescens Ulex gallii Blechnum spicant Calluna vulgaris Asplenium trichomanes Crataegus monogyna Vaccinium myrtillus Deschampsia flexuosa Molinia caerulea Deschampsia flexuosa Salix spp. Agrostis capillaris Polytrichum commune Sphagnum capillifolium Sedum anglicum Sorbus aucuparia Calluna vulgaris Pteridium aquilinum Sphagnum papillosum Umbilicus rupestris Ulex europaeus Carex binervis Vaccinium myrtillus Sphagnum recurvum Ulex gallii Deschampsia flexuosa Trichophorum cespitosum Galium saxatile Vaccinium myrtillus Juncus squarrosus Vaccinium oxycoccos Molinia caerulea Trichophorum cespitosum
77 Regional characteristics
The whole of the Principality of Wales and substantial areas of upland in England, including hill-edge, have been covered by ground survey to Phase 1 standard but coverage is not complete. Moreover, more detailed descriptions of plant communities in hill-edge habitats are much less widely available. In contrast, LCM 2000, which has been used for the modelling component of this review, has comprehensive coverage and distinguishes many of the important habitat types in the same way as ground-based descriptions of habitats. Nonetheless, there are some inconsistencies in classification.
Grasslands present the greatest problems for interpretation of satellite imagery, and the different subclasses of grassland have been distinguished in LCM 2000 with the aid of 'acid sensitivity' maps. Classification of some habitats depends on the density of certain dominant species. For example dwarf shrub heath may be relatively open and still be classed under this main heading in LCM 2000, whereas under Phase 1 surveys, sparsely distributed shrubs would probably be classed as a dwarf shrub heath/grassland mosaic.
The full extent of Pteridium may not be highlighted by LCM 2000 since dissected stands may be overlooked. Bogs, as defined under LCM 2000, probably refer largely to blanket bog in upland areas that lie outside the scope of this review. Many of the wet habitats discussed below are probably too localised to be identified as a dominant land-cover type in most of the land parcels identified on the LCM2000 map.
Information derived from the GIS analysis of LCM2000 (see previous chapter) has been used to summarise the extent of the major hill-edge habitats, and to note regional differences. The resultant list of habitats provides a framework for subsequent descriptions of plant communities on the hill-edge.
Rough and semi-natural grasslands contributed the greatest areas to hill-edge in all regions, except in the North York Moors and Northumberland where conifer plantations were particularly important. Significant areas of calcareous grassland were recorded in the North Pennines, Bowland and the Shropshire Hills. Neutral grasslands were particularly important in the North Pennines, Bowland and Northumbria. Generally acidic communities represented the greatest grassland area at the hill-edge, although very low areas were recorded for the North Pennines and North York Moors. However, it is difficult to distinguish between grassland types using satellite imagery. LCM 2000 distinguished grassland types at subclass level using an acid sensitivity map. There may therefore be some error in these estimates. It should also be noted that LCM 2000 includes semi-natural pastures with Juncus spp. under acid grasslands, whereas in the following discussion of communities Juncus pastures are included with habitats of wet or waterlogged soils. Improved grasslands and arable fields also occurred at the hill-edge but these habitats did not account for more than 5% of the area in any region.
Dwarf shrub heaths and bogs were all very minor components of the hill-edge vegetation, although small areas of these habitats occurred quite frequently, and they were widespread in Radnor.
Extensive conifer plantations have been excluded from the modelling study, many smaller areas of afforestation fall within the definition of hill-edge. In most areas, coniferous
78 woodland accounted for between 5 and 10% of the hill-edge area. However, in the North York Moors, Northumberland and the Cambrian ESA conifers were the major land cover, accounting for between 29 and 45% of the hill-edge.
Broad-leaved and mixed woodland also typically represented between 5 and 10% of the hill- edge, distributed across many small fragments. Notable exceptions were Radnor, where semi-natural woodland represented only a very small area, and Dartmoor, Exmoor and the North York Moors where it represented around 20% of the hill-edge land cover. Mixed woodland was particularly important in the North York Moors.
Surprisingly less than 5% of the hill-edge area was dominated by Pteridium in most regions, although LCM 2000 may underestimate the extent of this habitat where stands are dissected, and in the field the extent of Pteridium may by exaggerated by its inherent visual impact. A significant proportion of land in the Shropshire Hills and in the Lake District National Park (12% and 34% by area respectively) was dominated by Pteridium.
Summary
x Rough and semi-natural grasslands were the most widespread habitats on the hill-edge in England and Wales. x Most grassland was acidic. However, significant areas of calcareous grassland were recorded from the North Pennines, Bowland and the Shropshire Hills. Neutral grasslands were particularly important in the North Pennines, Bowland and Northumbria. x Dwarf shrub heaths comprised a very minor component of the hill-edge nationally but were widespread in one area of Mid-Wales (Radnor). x Conifer plantations covered between 5-10% of the hill-edge in England and Wales. However, the percentage of the hill-edge covered by plantations varied considerably between regions and was particularly high (>29%) in Northumberland, and North York Moors National Parks and in the Cambrian Mountains ESA. x Broad-leaved and mixed woodlands comprised 5-10% of the hill-edge in England and Wales but cover varied regionally and was high (>20%) in Dartmoor, Exmoor and the North York Moors. x Less than 5% of the hill-edge in England and Wales was covered by dense stands of bracken Pteridium aquilinum.
Habitats
Grassland
A range of grassland types occurs on the hill-edge. Unimproved rough grazings, acid and calcareous, generally lie outside enclosures (Anon, 2001c; Rodwell, 1998), or at the limits of enclosure especially where large enclosures extend high up the hillside (e.g. allotments in the Yorkshire Dales), or where land has reverted from previous improvement. Inbye land associated with the hill-edge will generally be semi-improved; those which have reverted from improvement or occasionally semi-natural mesotrophic grasslands. Rough grasslands in wet areas dominated by rushes are discussed in a later section. In some circumstances, more improved swards or hay meadows, that are more characteristic of improved agricultural land, are included in the hill-edge zone where these habitats are interspersed with other more typical hill-edge habitats. This summary presents information from the major habitat types,
79 although inevitably many of these communities will intergrade with each other across unenclosed land and within enclosed fields.
In a study of upland parishes in 10 areas in England and Wales, Ball et al. (1981) surveyed a range of habitats from highly improved pastures extensively managed heathland. The authors recognised four types of improved pasture, four rough grazings and three types of grass- dominated heath that are summarised below. These habitats are all probably found at the hill- edge, although improved pastures will represent only a very limited area.
Highly improved grasslands (limited relevance to hill-edge):
Herb rich Lolium grassland: recently resown swards with a range of agricultural weeds Lolium grassland: Agrostis capillaris and Holcus lanatus major co-dominant species Lolium/Trifolium grassland: codominants Lolium/Holcus/Pteridium grassland: on shallower soils than other improved categories.
Table 4.4. Constant species (80-100%) in improved grasslands Herb rich Lolium Lolium Lolium/Trifolium Lolium/Holcus/ Pteridium Bellis perennis Achillea millefolium Agrostis capillaris Agrostis capillaris Cerastium fontanum Agrostis capillaris Cerastium fontanum Cerastium fontanum Lolium perenne Bellis perennis Cynosurus cristatus Cynosurus cristatus Trifolium repens Cerastium fontanum Holcus lanatus Holcus lanatus Cynosurus cristatus Lolium perenne Lolium perenne Dactylis glomerata Trifolium repens Plantago lanceolata Holcus lanatus Rumex acetosa Lolium perenne Trifolium repens Plantago lanceolata Ranunculus acris Rumex acetosa Trifolium repens Source: Ball et al. (1981)
Rough grazing: Agrostis/Juncus: high species diversity with herb rich flushes, scattered Pteridium, Rubus fruticosus, trees Festuca/Juncus: more coarse grasses (wetter than Agrostis/Juncus), Deschampsia cespitosa, Agrostis capillaris, Nardus stricta Agrostis/Holcus: well drained, moderate slope, high species diversity Festuca/Agrostis: moderate slopes, fewer trees.
Festuca/Juncus and Festuca/Agrostis communities were found on more acidic soils and Festuca/Agrostis was the most frequent type of rough pasture on steep slopes. The Agrostis/Juncus and Agrostis/Holcus communities were found under less acidic conditions, at lower altitudes and generally within enclosures.
80 Table 4.5. Constant species (80-100%) in rough grazings Agrostis/Holcus Agrostis/Juncus Festuca/Agrostis Festuca/Juncus Achillea millefolium Agrostis capillaris Agrostis capillaris Anthoxanthum odoratum Agrostis capillaris Anthoxanthum odoratum Anthoxanthum odoratum Cerastium fontanum Cerastium fontanum Cirsium palustre Cerastium fontanum Cirsium palustre Holcus lanatus Holcus lanatus Festuca ovina Festuca ovina Plantago lanceolata Juncus articulatus Galium saxatile Galium saxatile Potentilla erecta Juncus effusus Holcus lanatus Holcus lanatus Rumex acetosa Leontodon spp. Potentilla erecta Juncus articulatus Trifolium repens Potentilla erecta Trifolium repens Juncus effusus Prunella vulgaris Nardus stricta Ranunculus acris Polytrichum spp. Ranunculus flammula Potentilla erecta Ranunculus repens Prunella vulgaris Rumex acetosa Ranunculus repens Trifolium repens Rumex acetosa Trifolium repens Source: Ball et al. (1981)
Grassy heaths:
Festuca/Nardus/Vaccinium: moderate to steep slopes generally drier than other categories of grass heath Festuca/Nardus/Molinia: wet grassy heath with species typical of wet areas, such as Eriophorum, Juncus, Narthecium, often present Festuca/Vaccinium: gentle to moderate slopes with good drainage.
Table 4.6. Constant species (80-100%) in grassy heaths Festuca/Nardus/Vaccinium Festuca/Nardus/Molinia Festuca/Vaccinium Deschampsia flexuosa Anthoxanthum odoratum Agrostis capillaris Festuca ovina Festuca ovina Deschampsia flexuosa Galium saxatile Galium saxatile Festuca ovina Juncus effusus Juncus effuses Galium saxatile Nardus stricta Juncus squarrosus Vaccinium myrtillus Potentilla erecta Nardus stricta Polytrichum spp. Potentilla erecta Sphagnum spp. Vaccinium myrtillus Source: Ball et al. (1981)
Acid grasslands
Acid grasslands are the most common habitats at the hill-edge, comprising a large proportion of B11 (unimproved acidic grassland) habitats described in Phase 1 surveys and representing marginal grazing land between improved and moorland areas (Drewitt, 1991). They are usually plagioclimax communities prevented from developing into woodland communities, from which they were originally derived, by grazing (Rodwell, 1998). Abundant species include: Agrostis capillaris, Festuca ovina, Nardus stricta, Juncus squarrosus, Galium saxatile, and Potentilla erecta (Drewitt, 1991). Acid grasslands are also found on unenclosed moorland. They are dominated by Nardus stricta and Molinia caerulea, and are sometimes
81 referred to as 'white moor' as opposed to 'black moor' which are dominated by dwarf shrub heath species. Acid grasslands are generally species poor and are often regarded only as a degraded form of more valuable habitats such as dwarf shrub heath. Their major value in conservation terms is often regarded as a buffer to other habitats (Anon., 1995e).
The two most extensive NVC plant communities in acid grasslands on the hill-edge are probably U4 and U5. U4 Festuca ovina – Agrostis capillaris – Galium saxatile grasslands are found on free-draining mineral soils but can be invaded by Pteridium aquilinum where grazing pressure is heavy or non-selective (Dixon, 1984). In the Pennine Dales ESA (which comprises enclosed grassland), species poor U4 grassland was recorded in allotment land (ADAS, 1996b), with common species outlined in Table 4.7.
Table 4.7. Species recorded in U4 grassland in the Pennine Dales Common Frequent grasses Common forbs Occasional forbs grasses/rushes Agrostis capillaris Nardus stricta Potentilla erecta Vaccinium myrtillus Juncus squarrosus Festuca ovina Galium saxatile Vaccinium vitis-idaea Anthoxanthum odoratum Deschampsia flexuosa
U4 grasslands give way to U5 Nardus stricta – Galium saxatile communities on wetter soils (Jerram et al., 1998). Where conditions are particularly waterlogged, Molinia caerulea becomes dominant (Dixon, 1984) with Deschampsia cespitosa sometimes present (Sinclair, 1983). Generally U4 communities are found at lower altitudes, often within enclosures, whereas U5 communities occur higher up the slope (Penford et al., 1989). Where U4 and U5 grade into heaths, sub-communities are recognised (Jerram et al., 1998). Rushes (especially Juncus squarrosus) are often abundant in wet, poorly drained areas particularly where the sward is overgrazed or poached (Miller et al., 1984). However, Francis et al. (1989) noted that Juncus effusus was not necessarily associated with particularly flushed or wet areas. These acid grasslands are most commonly found at the limits of enclosure where little if any improvement has occurred, or on unenclosed land where heathland has been degraded by excessive grazing (Francis et al., 1989). Where improvement has been extensive, they are found on steep or rocky areas where accessibility is limited, or sometimes as reversions from semi-improved grasslands (Francis et al., 1990).
Other acid grassland NVC communities that are associated with the upland fringe and are therefore potentially found at the hill-edge include U2 Deschampsia flexuosa and U3 Agrostis curtisii grasslands (Rodwell, 1998). U2b Vaccinium myrtillus sub-community occurs, probably at the limits of the hill-edge, and has been recorded on higher allotment land in the Pennine Dales (ADAS, 1996b). It is a species poor community, and the only other common species is Calluna vulgaris. U3 grassland is restricted to the south west of England and will therefore be a component of the hill-edge only in Exmoor and Dartmoor. It can occur as a seral stage in the regeneration of heath communities, but in many areas it is a stable habitat because of excessive grazing and burning. Other relatively abundant species of U3 grassland include Festuca ovina, Danthonia decumbens and Agrostis capillaris, and where these species become more common this community grades into the U4 grassland (Rodwell, 1998).
Although acid grasslands are generally considered to be species poor, overgrazing and burning have probably contributed to the paucity of species present in these habitats and 60 species of flowering plants are dependent on acid soils in North Western Britain (Andrews &
82 Rebane, 1994b). Some areas can be extremely rich, particularly for lower plants; Francis et al. (1989) reported some north facing areas of acidic grassland were rich in bryophytes, and Francis et al. (1990) recorded a range of club-mosses on several commons in Plynlimon, and populations of Festuca vivipara, largely restricted to ledges. In Dartmoor, grass/heath areas support populations of Viola lactea (very local distribution) and Euphrasia vigursii (BAP species, although this may be restricted to lowland heaths). Acid grasslands can be affected by inappropriate grazing, afforestation, neglect leading to Pteridium infestation and agricultural intensification (Anon., 1995e; Anon., 2001d).
Mesotrophic grasslands
Mesotrophic grasslands form a component of the hill-edge. However, most mesotrophic grasslands in upland areas represent heavily improved communities, which will usually fall outside the definition of hill-edge. Semi-natural mesotrophic grasslands are rare because they occur on relatively dry areas with even terrain, and so are readily improved (Backshall et al., 2001). Greatest botanical interest is present in meadows and pastures that have undergone little improvement in terms of: reseeding, fertiliser application, drainage, herbicide inputs and silage production. Grassland managed for silage is less botanically valuable than that managed for hay because it receives greater herbicide and fertiliser inputs and is cut earlier, which does not allow plants to set seed (Younger & Smith, 1993). However, liming is considered important to maintain more diverse mesotrophic communities albeit in infrequent applications (Askew, 1993). Bain (1987) reported a range of species as common in enclosed land of upland Wales (Table 4.8).
Table 4.8. Common species of enclosed grasslands of upland Wales Dry improved (heavily improved, Damp enclosed pasture (greater drained and reseeded) species diversity than dry) Lolium perenne Agrostis capillaries Agrostis capillaris Holcus lanatus Poa annua Lolium perenne Trifolium repens Poa annua Achillea millefolium Cynosurus cristatus Ranunculus repens Trifolium repens Ranunculus repens
Jerram et al. (1998) surveyed a small number of improved or semi-improved grasslands in their survey of moorland and recorded: MG10 Holcus lanatus - Juncus effusus MG9 Holcus lanatus - Deschampsia cespitosa MG6b Lolium perenne - Cynosurus cristatus, Anthoxanthum odoratum sub-community MG6a Lolium perenne - Cynosurus cristatus (where greatest improvement)
The Pennine Dales ESA encompasses enclosed grasslands in the upper reaches of 26 valleys. The monitoring of this ESA is an important source of information on communities of largely neutral grasslands. Four mesotrophic grassland communities (and one sub-community) were identified (Table 4.9) which, given the descriptions of distribution, may occur at the hill-edge in some circumstances (ADAS, 1996b). They represent semi-improved meadows and pastures often found towards the dale heads.
83 Table 4.9. Mesotrophic grassland communities recorded in the Pennine Dales which may be associated with the hill-edge. NVC community Character and distribution MG3 Anthoxanthum odoratum – Geranium Herb rich meadows largely mesotrophic but with sylvaticum calcicolous species A few dale heads Traditional hay meadow management MG3a Bromus hordeaceus ssp. hordaeceus sub- Species rich meadows community Less improved more common towards dale heads MG6b Lolium perenne – Cynosurus cristatus, Grass dominated pasture Anthoxanthum odoratum sub-community At lower dale sides and bottoms MG8 Cynosurus cristatus – Caltha palustris Relatively species rich pasture Upper parts of dales MG10a Holcus lanatus – Juncus effusus, typical Species poor wet rough pasture sub-community Where drainage is failing, often reverting from MG6b Source: (ADAS, 1996b)
Most mesotrophic grassland communities are more extensive in lowland areas, however MG3 Anthoxanthum odoratum – Geranium sylvaticum occurs only in upland England in areas where traditional hay meadow management continues, although it is now restricted to higher valleys of the Pennines and Lake District (Rodwell, 1998). Species associated with the MG3 and MG3a communities recorded in the Pennine Dales ESA are summarised in Table 4.10.
Table 4.10. Species recorded in hay meadow communities in the Pennine Dales Mesophytic grasses Forbs Montane species Calcicolous species MG3 Festuca rubra Geranium sylvaticum Polygonum viviparum Briza media Holcus lanatus Sanguisorba officinalis Viola lutea Lotus corniculatus Anthoxanthum odoratum Trollius europaeus Galium verum
MG3a Holcus lanatus Plantago lanceolata Trollius europaeus Anthoxanthum odoratum Trifolium pratense Cirsium heterophyllum Festuca rubra Conopodium majus Alchemilla spp. Cynosurus cristatus Rhinanthus minor Source: (ADAS, 1996b)
Calcareous
Calcareous grasslands represent a much smaller area of the uplands than acid grasslands but support a much larger number of species (more than 130 flowering plants) (Andrews & Rebane, 1994b). These grasslands may include many rare and uncommon species (Anon., 2001c), although heavy grazing greatly restricts the species diversity (English Nature, 2001). They form part of the habitat mosaic usually outside enclosures and are generally managed as rough grazing (Anon. 2001c). An estimated 10 000 ha of upland calcareous grassland exist in England, with the largest areas in Cumbria and the north Pennines (Backshall et al., 2001). Carboniferous limestone is the most common base rich substrate in England and Wales, found in north and south Wales and the north Pennines (Anon. 2001c). In other areas, calcareous grassland habitats occur at a localised scale where base rich strata are exposed. These habitats can be damaged or lost because of agricultural intensification, overgrazing
84 (particularly in summer), scrub encroachment, erosion, quarrying and filling in of abandoned quarries, acidification and nitrogen enrichment by atmospheric deposition (Anon. 2001c).
Several calcareous grassland NVC communities have been recorded in upland areas. CG9 Sesleria albicans – Galium sterneri, a community of free draining but moist soils which is only found in upland areas, is frequent on the carboniferous limestone of the north Pennines (Rodwell, 1998). CG10 Festuca ovina – Agrostis capillaris – Thymus praecox is a sub- montane community scattered through much of the British uplands, as small stands usually less that 1 ha (Rodwell, 1998), and has been recorded in the North Pennines, Cumbria and parts of Wales (English Nature, 2001). A survey of moorland in the North York Moors (Jerram et al., 1998) recorded small areas of CG7 Festuca ovina – Hieracium pilosella – Thymus praecox/pulegioides grassland (although this may not have been at the hill-edge) where limestone strata were exposed, although this is primarily a habitat of lowland areas over chalk Rodwell, 1998).
Table 4.11. Species recorded in CG2c grassland Grasses Forbs Sedges Anthoxanthum odoratum Lotus corniculatus Carex caryophyllea Festuca rubra Sanguisorba minor Carex flacca Agrostis capillaris Linum catharticum Briza media Primula farinosa Sesleria caerulea
Table 4.12. Species present in calcareous grasslands of Upper Teesdale Common Abundant Other species (local distribution) Sesleria caerulea Pilosella officinarum Polygonum viviparum Briza media Plantago lanceolata Antennaria dioica Koeleria macrantha Succisa pratensis Potentilla crantzii Carex panicea Galium sterneri Draba incana Campanula rotundifolia Gentianella amarella Selaginella selaginoides Euphrasia officinalis agg. Helianthemum nummularium Carex capillaris Linum catharticum Carex flacca Kobresia simpliciuscula Thymus polytrichus Carex caryophyllea Primula farinosa Viola riviniana Helictotrichon pratense Minuartia verna Danthonia decumbens Viola rupestris* Polygala amarella* Gentiana verna** Carex ericetorum*** Hippocrepis comosa Plantago maritima Anthyllis vulneraria Epipactis atrorubens * Very rare; ** Very locally frequent; *** Rare
In the Yorkshire Dales National Park, calcareous grasslands occur in the southern part of the park within large enclosures on sloping hillsides, whereas in the north they are restricted to small steep banks where outcrops of calcareous substrates occur (Drewitt, 1991). Species with restricted national distributions include: Sesleria caerulea, Galium sterneri and Primula
85 farinosa. Monitoring of the Pennine Dales ESA identified some of these grasslands as CG2c Festuca ovina – Avenula pratensis grassland (ADAS, 1996b). Common species are outlined in Table 4.11. These are particularly species rich communities with over 40 species m-2 recorded in many quadrats.The most botanically valuable calcareous grasslands are rare arctic-alpine communities concentrated in Upper Teesdale particularly on the sugar limestone areas. These habitats are concentrated higher up the hill on moorland areas, but extend to the hill-edge in places. Some species present are confined to the region. Table 4.12 summarises species recorded by Ratcliffe (1978) on dry limestone grassland in the area.
Rocky areas
This term is used here to represent habitats dominated by bare rock including rock outcrops and scree, and possibly tors and occasionally limestone pavement in some areas. These may be botanically important for pioneer species (particularly lower plants) that specialise in such habitats but also as 'refuges' for a range of species susceptible to grazing, by creating inaccessible sites because of the terrain or topography. Helianthemum nummularium, Scabiosa columbaria, Geranium sanguineum are examples of species which benefit from the absence of grazing, and scattered trees and shrubs may also establish (Drewitt, 1991).
In the Yorkshire Dales National Park, the most abundant species on limestone screes were three spleenworts: Asplenium trichomanes, Asplenium viride and Asplenium ruta-muraria. Species on scree derived from acid substrates included Dryopteris spp., Rumex acetosella, Digitalis purpurea, Deschampsia flexuosa, Ceratocapnos claviculata and Cryptogramma crispa (Drewitt, 1991). The latter two species both have local distributions.
The commons survey of Radnor District (Penford et al., 1990) identified several notable species associated with rock or scree areas, with over 100 bryophyte species recorded at one site. Records of Peltigera apthiosa and three other species represent the only record of these lichens in Powys. Sedum forsterianum, Gymnocarpium dryopteris and Saxifraga hypnoides all have local distributions, and Cystopteris fragilis and Phegopteris connectilis are notable species of fern. Sorbus porrigentiformis, a rare species, possibly endemic to limestone crags and woodlands, was also recorded.
The Upland Vegetation Survey of Wales, carried out in the 1980s was essentially a study of moorland, but other communities were occasionally surveyed. Sedum anglicum, C. fragilis, T. polytrichus, Homalothecium sericeum, Tortella tortuosa, Asplenium trichomanes, Polypodium vulgare, and Umbilicus rupestris were recorded on rocky outcrops (Wales Field Unit, 1982b), some of which represent part of the hill-edge.
In Dartmoor, rocky habitats are important for a range of rare and endangered species, particularly lichens and ferns. For example, Asplenium septentrionale, Asplenium obovatum and Hymenophyllum wilsonii are all rare or locally distributed ferns that occur on rocky habitats in Dartmoor (English Nature & Dartmoor National Park Authority, 2001). Also, Hypericum linariifolium is a Red Data Book species that is internationally rare and is being threatened by scrub encroachment. It grows on scree slopes in the south west of England and in Wales (Dartmoor Biodiversity Steering Group, 2001), and nationally significant populations are found on screes of the Upper Teign valley in Dartmoor (English Nature & Dartmoor National Park Authority, 2001).
86 Metalliferous Communities
Metallophyte communities occur on toxic mining spoil or outcrops of veins of heavy metals which most species cannot tolerate (Rodwell, 2000). In these circumstances collections of interesting and sometimes rare species occur at a very local scale, and some communities are recognised as having international importance (Peak District National Park, 2002c). This habitat is concentrated in the Derbyshire and Yorkshire Dales and in the north Pennines and is largely a product of centuries of mining (Rodwell, 2000). Although a complex mosaic of vegetation types may be present because of a range of topography and of waste material, only one NVC community is recognised, the OV37 Festuca ovina – Minuartia verna where Festuca ovina populations have developed some resistance to heavy metals.
M. verna is a nationally uncommon species found on lead rakes in the Peak District and Pennine Dales. Coeloglossum viride and Gymnadenia conopsea (both local distribution) occur in the Peak District (Peak District National Park, 2002c) and Cochlearia pyrenaica (local) and Thlaspi caerulescens (very local) are both found in the Yorkshire Dales National Park (Drewitt, 1991).
Communities of wet or waterlogged soils
A range of communities is associated with wet areas present at the hill-edge under both acid and base rich conditions. Wet pastures and marshy grasslands occur on shallow slopes that are poorly drained and the soils remain waterlogged for significant periods. Wet flushes and soligenous mires exist on steeper slopes where water flow occurs. Wet or waterlogged habitats can extend over considerable areas, or be very small-scale flushes often too small to map (Francis et al., 1990). These habitats are generally dominated by rushes, sedges and mosses, and by Molinia caerulea in drier areas. They often occur in complex mosaics and communities intergrade with grassland communities often within the same fields. Juncus spp. are often associated with overgrazing or poaching (Cadbury, 1999). Waterlogged sites may be species rich but those dominated by Molinia caerulea are generally species poor (Francis et al., 1989; Francis et al., 1990). Blanket bogs are not included in this review, because they are largely confined to true moorland habitats.
Acid
Acidic wet habitats are common where drainage is poor and occur in both enclosed and unenclosed areas throughout England and Wales, but particularly in western regions. They are very variable, but are often species poor communities (Francis et al., 1990), although they can include species restricted to waterlogged habitats such as Hydrocotyle vulgaris (Drewitt, 1991). Rush pastures are usually dominated by tussocky Juncus effusus (Francis et al., 1989), or by Juncus acutiflorus in areas of greater nutrient richness (Drewitt, 1991). Rush pastures and communities dominated by Molinia caerulea are the most extensive mire habitats at the hill-edge. Flushes and soligenous mires form where there is significant water movement either as emergent drainage from springs or from localised runoff (Coulson et al., 1992). These habitats are dominated by rushes, sedges and sphagnum species, such as Sphagnum recurvum, which are dependent on moving water (Coulson et al., 1992). In more waterlogged areas comprising shallow peat or peaty gleys, the calcifuge species, Juncus squarrosus is dominant (Coulson et al., 1992), commonly forming swards at the margins of heather and Nardus moorland (Sinclair, 1983).
87 Juncus effusus dominates both M23 Juncus effusus/acutiflorus – Galium palustre and M6c Carex echinata – Sphagnum recurvum/auriculatum, Juncus effusus sub-community, which are both common habitats at the hill-edge (Francis et al., 1990) on enclosed and unenclosed land (Rodwell, 1991b). M6c is a diverse community in terms of both species and structure, whereas M23 is less species rich, although there can be considerable diversity of associated species between sites. M25 Molinia caerulea – Potentilla erecta communities are common in extensive tracts on shallow peats often on gently sloping land (Francis et al., 1990) and are often found above valley bogs (Rodwell, 1991b). They are typically very species poor, with only Potentilla erecta occurring frequently, but with rushes (J. acutiflorus and Juncus effusus) and a few dicotyledonous species sometimes present. In the upland fringes, this community has often been replaced by conifer plantations because the soils are more suitable for afforestation than under many other communities (Rodwell, 1991b).
One other acidic mire NVC community may also occur occasionally at the hill-edge in some regions. M21 Narthecium ossifragum – Sphagnum papillosum is more usually a community of lowland valley mires. However it does occur on the fringes of Dartmoor, Exmoor, in Wales and the North York Moors (Rodwell, 1991b). It is dominated by Sphagnum spp. with occasional forbs and sparse Erica tetralix and Calluna vulgaris.
Acidic marshy grassland was the dominant community on common land in Carmarthenshire surveyed by Penford et al. (1989). Their Phase 1 survey recognised two categories of this grassland (acidic flushes were described separately) both dominated by Molinia caerulea. The first, relatively species poor, was equivalent to the M25 NVC community, with only Potentilla erecta frequent in the vegetation. The second category described more species rich communities, of wetter, lower lying ground, which usually occupied smaller areas. This habitat included M23 and a type of rhôs pasture, and Penford et al. (1989) indicate that this is a particularly species rich community for common land in the area. This habitat occurred on moist acid to neutral soils, on gently sloping ground with poor drainage. Species composition included: Cirsium palustre, Lotus pedunculatus, Ranunculus flammula, Mentha aquatica, Cardamine pratensis and wet heath species: Erica tetralix, Narthecium ossifragum, Succisa pratensis, Carex viridula ssp. oedocarpa, Carex pulicaris, Wahlenbergia hederacea and Pedicularis sylvatica.
Base rich
Base rich flushes may extend over significant areas in some locations but also occur at a very local level within predominantly acid areas. They support a quite different range of plant species than acid flushes, ranging from species of highly basic to simply less acid conditions and tend to support a wider range of species than acid flushes. In Wales, Francis et al. (1990) recorded Carex hostiana, C. pulicaris and Pinguicula vulgaris on base rich flushes. In the Yorkshire Dales National Park, notable species of base rich flushes included Primula farinosa and Parnassia palustris (Drewitt, 1991). Similar species are found in marshy areas over the sugar limestone in Teesdale, and Kobresia simpliciuscula, a calcareous species of local distribution is abundant in some areas (Ratcliffe, 1978).
Two NVC communities of base rich flushes have been recognised in upland areas. M26 Molinia caerulea – Crepis paludosa is found only in the uplands and is generally restricted to the Pennines and the Lake District (Backshall et al., 2001). It occurs around open waters and mires, but also, in the context of hill-edge habitats, on flushed slopes (Rodwell, 1991). M10 Carex dioica – Pinguicula vulgaris mires are species rich communities dominated by small
88 sedges, forbs and bryophytes. They are widespread in the north of England, but are very locally distributed (Rodwell, 1991b). In the North York Moors, M10a Carex dioica – Pinguicula vulgaris mire has been recorded in base rich flushes, generally on steep slopes where limestone outcrops occur close to the surface (Jerram et al., 1998). Table 4.13 summarises mire communities which have been recorded in areas associated with the hill- edge.
Table 4.13. NVC communities of wet or waterlogged areas. Community Sub- Comments community M25 Molinia caerulea – Potentilla Throughout western Britain 3 erecta 1,2 On acid flushes along seepage lines 4 a - small peripheral stands on most moors 5 a - Erica tetralix M23 Juncus effusus/acutiflorus – Widespread through western Britain Galium palustre 1,2,4 Moist soils on gently sloping ground. Characteristic of relatively unimproved or reverted pasture 3 M6 Carex echinata - Sphagnum Ubiquitous in upland fringes 3 recurvum/auriculatum 2,4 Base-poor soligenous mires 3 especially c - c - species poor; found along stream courses 5 Juncus effusus and seepage lines 6 generally 200-400 m 3 M21 Narthecium ossifragum – Waterlogged acid and nutrient-poor peats 3 Sphagnum papillosum Recorded on two commons 4 M26 Molinia caerulea – Crepis Local distribution – northern Pennines paludosa Moderately base rich and calcareous peats 3 M10 Carex dioica – Pinguicula a Restricted to north western regions vulgaris Soligenous mires of mineral soils and shallow peats 3 1 Backshall et al., 2001 2 Francis et al., 1989 3 Rodwell, 1991b 4 Francis et al., 1990 5 Jerram et al., 1998 6 Penford et al., 1989
Bracken
The ecology of Pteridium aquilinum, potential for control and methods of sustainable management have been extensively studied and thoroughly reviewed (e.g. Marrs et al., 2000; Pakeman et al., 2000). The following narrative, therefore, aims simply to summarise the importance of Pteridium in the context of the hill-edge.
The distribution of Pteridium is concentrated in the west of Britain under extensive grazing systems at 200-400 m (Pakeman et al., 2000), but extends up to 500-600 m (Institute of Terrestrial Ecology, 1978). It is most commonly found on well-drained mineral soils (at least well drained at the surface) (Institute of Terrestrial Ecology, 1978; Garnett, 1988). However, Pteridium does need moisture (Smith, 1986), and Brown (1986) suggests that it may be spreading to wetter areas by colonisation of peat that is damaged by fire. It is often found on sloping ground of low agricultural value (Miller et al., 1984) such as steep valley sides and
89 gullies, and at the moorland fringe (ADAS, 1997e). Pteridium is, therefore, an important component of the hill-edge. It occurs throughout England and Wales and occurs locally in dense stands. In some areas, it dominates the hill-edge vegetation, as in Wales (Hobson, 1985) whereas in the North York Moors, 20% of the moorland area (essentially the area of unenclosed land) was dominated by Pteridium in 1995/6 (where dominance is defined as 70% of the ground cover in July and more than 5 cm of litter) (Brown, 1986). Common land often has extensive tracts of Pteridium. In a survey of common land in Radnor district, Penford et al. (1990) reported that continuous Pteridium was the most abundant habitat on many commons and covered 33% of the total common area, although not all common land surveyed was in upland areas.
Pteridium was originally a woodland species, but has thrived with the removal of tree cover. The perceived expansion of the species is unwelcome from a farmer's perspective, because it reduces the grazing value of the land, is poisonous to stock, the litter is a major habitat for sheep ticks, there is the potential for soil erosion following control and the spores are carcinogenic (Hinsley et al., 1999). Control of Pteridium is difficult on common land because of the problems of organising expensive control measures where land is owned or utilised by many individuals, although estover rights (rights to cut Pteridium and rushes for bedding) are still exercised in some areas of Wales (Hughes & Aitchison, 1986). It also shades out other species and the botanical composition of Pteridium stands is particularly limited where Pteridium forms very dense stands (Pakeman & Marrs, 1992). The NVC community where Pteridium is dominant in upland areas (U20) is characteristically very species poor with some shade tolerant and calcifuge species (Rodwell, 1998). Common land surveys of Wales did not always detail the understorey species in Pteridium stands but suggest greater species diversity where stands were sparse (Penford et al., 1990; Penford et al., 1989). In a survey in Teesdale, dense bracken stands were found to support a ground layer of only Deschampsia flexuosa, whereas Agrostis capillaris, Festuca ovina, Anthoxanthum odoratum and Nardus stricta were recorded under shorter sparse stands (Lee et al., 1986). The authors speculate that Deschampsia flexuosa survives in the dense stands because of its tolerance of shade. However they concluded that soil factors were more important for the species composition of the understorey.
At a local scale, Pteridium stands may be valuable botanically because they contain relict woodland forb communities particularly where frond densities are relatively low, and indeed some areas support communities of international importance.
Common species: Hyacinthoides non-scripta Oxalis acetosella Viola riviniana Primula vulgaris
Rare/local species: Cornus suecica (very rare in England) Trientalis europaea (rare in N. Eng) both these species are found in Pteridium stands on the North York Moors (Pakeman & Marrs, 1992) Ceratocapnos claviculata (locally common) Colchicum autumnale Polygonatum multiflorum
90 It has been suggested that Pteridium can act as a nurse crop for woodland and scrub, by reducing the grazing pressure during summer thereby allowing the regeneration of woody species (Francis et al., 1989). Garnett (1988) reported a greater number of trees per hectare associated with Pteridium than with other ffridd habitats. However, Hinsley et al. (1999) point out that Pteridium offers no protection from grazing during the winter when fronds have died back.
Pteridium stands are, however, an important component of the vegetation mosaic at the hill- edge, providing a valuable habitat for some invertebrate and bird species. Stuart (1996) suggests that traditional management techniques of light grazing by cattle, ponies, or horses, plus manual cutting or narrow flailing of seasonal paths and additional small areas, are required to encourage growth of Viola spp. which are valuable for fritillaries (see invertebrate section).
Shrub
Dwarf shrub heath vegetation is more commonly associated with moorland areas that have received considerable attention from researchers and conservationists. These communities are usually dominated by Calluna vulgaris and are internationally important. Some are protected under the EU Habitats Directive (Thompson et al., 1995). These communities occur between enclosed agricultural land and the montane zone (Anon., 1995f). However, shrub species also extend into areas that should be considered as hill-edge rather than true moorland and are sometimes found within enclosures, particularly in areas such as the Pennine Dales, where extensive allotment land extends high up the hillside. In some areas, stands of shrub species may be significant, forming typical shrub dominated communities. Elsewhere shrubs are sparsely distributed or form a mosaic with grassland representing a transition between shrub and grassland communities.
Calluna vulgaris is the most common dwarf shrub heath species of upland England and Wales. Vaccinium myrtillus is more locally dominant, often representing a transitional stage between heathland and grassland (Bardgett et al., 1995). Erica tetralix, Erica cinerea, Empetrum nigrum, Vaccinium vitis-idaea are locally frequent. Erica tetralix is found on wetter ground and Erica cinerea has an oceanic distribution (Coulson et al., 1992). The distribution of Ulex gallii has a southern and westerly bias, and is found on heaths in SW England, Wales and the southern Pennines.
Dwarf shrub heath communities are relatively species poor (Thompson et al., 1995), but some are very rich in bryophytes and lichens. However, many heaths are heavily managed by burning to maintain a building phase of heather, and are typically very species poor. Excessive grazing, afforestation and conversion to pasture may also threaten these habitats (Anon., 1995f), particularly at the hill-edge.
Two NVC shrub communities have been recorded in the ffridd - H12 and H8 (Bates, 1992), and H4 south western heath occurs up to 500 m on dry sloping land on Dartmoor and is perceived to be part of the hill-edge. These are all communities listed under the EC 'Habitats Directive' (Thompson et al., 1995). Little further information on heathland NVC communities within hill-edge habitats is available. This is because heathland communities do not form extensive stands but are part of a complex mosaic with, or intergrade into, grassland communities, which are usually described as D5 and D6 dry/wet heath/acid grassland mosaics
91 under Phase 1 classification. Table 4.14 summarises heathland habitats recorded in the ffridd and those that are potentially found at the hill-edge.
Table 4.14. Heathland communities present or potentially present in hill-edge habitats. Community Distribution H4 Ulex gallii – Agrostis curtisii Restricted to the south west on moorland fringes of Dartmoor and Exmoor H8 Calluna vulgaris – Ulex gallii Upland fringes of Dartmoor, mid Wales and south Pennines. Patchily distributed on marginal grazing because soils suitable for improvement. H12 Calluna vulgaris – Vaccinium Most common heather dominated community across the uplands. myrtillus Found on gentle and hill slopes and on valley sides H9 Calluna vulgaris – Concentrated in south Pennines and North York Moors Deschampsia flexuosa Acidic and impoverished soils H10 Calluna vulgaris – Erica Scattered distribution through north west of England and Wales in cinerea the upland fringes Acidic to neutral free draining soils H18 Vaccinium myrtillus – Scattered through western uplands. Deschampsia flexuosa Steeper slopes at moderate to high altitudes. H21 Calluna vulgaris – Vaccinium Local occurrence in the Lake District. myrtillus – Sphagnum Cool, shady conditions e.g. north facing slopes. capillifolium Information from Rodwell, 1991b.
Scrub
The conservation value of scrub in Britain has recently been reviewed (Mortimer et al., 2000). This section will, therefore, summarise the main conclusions of that report with respect to upland scrub types that occur in England and Wales. Additional information from other sources has been included where appropriate. A separate account is given for Juniperus communis ssp. communis because it is the only scrub species that has intrinsic conservation value, rather than forming a valuable habitat for other plants and various animal groups.
The transition between woodland and scrub has been described in various ways, but Mortimer et al. (2000) define scrub as ranging from scattered bushes to a closed canopy dominated by shrubs and tree saplings generally less than 5 m high, with occasional scattered trees. However, Hobson (1985) recorded few scrub areas greater than 2 m because of grazing. At the limits of altitude or exposure, scrub forms a climax community but it is more often a seral community where succession to woodland is prevented by management (usually grazing but also burning). Scrub is usually a product of secondary succession on abandoned agricultural land or where grazing pressure has been relaxed but it may develop as a result of primary succession on screes or cliffs. It is a habitat which has often been overlooked in terms of conservation value, and agri-environment schemes generally concentrate on limiting scrub encroachment into valuable habitats (Mortimer et al., 2000), although some ESA prescriptions demand scrub management plans or consent for any management of scrub.
Scrub is an important habitat, although it can be regarded as an indicator of dereliction and much has been lost to agricultural improvement in terms of ploughing and reseeding (Good et al., 1995). However, Crataegus monogyna stands are widespread on steeply sloping valley sides (Good et al., 1990) at intermediate altitudes between 200 and 400 m (Good, 1995). It is
92 generally recognised that it is important to have some areas of scrub, which are particularly important for breeding birds (Garnett, 1988), although it can threaten other intrinsically valuable habitats. CEAS Consultants Ltd & Wye College (1993a) suggest that generally greater scrub cover would be of ecological benefit and that the balance between habitats should be shifted in favour of scrub by a reduction in grazing pressure. Dense areas of scrub are rare at the hill-edge and on common land, only occurred where grazing rights were not exercised (Camarthenshire - Penford et al., 1989), or where the steepness of the slope significantly reduced grazing pressure (Radnor - Penford et al., 1990). However, small and scattered scrub communities are frequent (Drewitt, 1991) and indeed are characteristic of the ffridd (Penford et al., 1990), although the Wales Field Unit (1982b) reported that scrub cover never exceeded 5%, and Good et al. (1995) estimated that Crataegus monogyna covered only 0.23 and 0.13% of land in two Welsh ESAs. Crataegus monogyna is the most common scrub species found in hill-edge habitats accounting for 74% of trees in a survey of the ffridd in mid Wales (Hobson, 1985). Other species include: Ulex europaeus (Ulex gallii in the south west of England and in Wales), Sorbus spp., Prunus spinosa (Penford et al., 1989), Salix spp.(on wetter areas), Acer pseudoplatanus, Corylus avellana, Fraxinus excelsior, Betula spp. and Juniperus in some areas.
Scrub requires low grazing pressure to regenerate and there is a widespread recognition that many upland areas of scrub are not regenerating (Penford et al., 1990). Significant regeneration was found to be restricted to exclosures (Good et al., 1995) and scrub is often restricted to steep slopes and areas relatively inaccessible to stock where grazing pressure is lower. Age-class distributions are usually skewed indicating that many remaining areas of scrub are not regenerating. Good (1995) recorded little or no regeneration at most sites surveyed in the Cambrian Mountain and Radnor ESAs, and suggested that there had been limited regeneration over the past 10 to 20 years. Generally scrub consisted of scattered individuals and some of the more dense clumps recorded were a result of clonal development from root suckers. Crataegus monogyna scrub was found to be positively associated with Pteridium stands, suggesting that Pteridium acts as protection against grazing, allowing successful establishment of seedlings (Good et al., 1995). However, Crataegus monogyna seedlings were not generally recorded in Pteridium stands, suggesting that competition for light is great in dense stands.
NVC communities which relate to scrub habitats include W19 Juniperus communis ssp. communis – Oxalis acetosella, largely recorded in the north of England, and W23 Ulex europaeus – Rubus fruticosus, recorded in the northern Pennines (Horsefield & Thompson, 1993) and at the margins of low lying moors in the North York Moors (Jerram et al., 1998). However, Mortimer et al. (2000) suggest that the NVC is not an adequate classification of scrub habitats because the ecological value is more often related to the structure, in terms of both vertical structure and the spatial relationship with other habitats, rather than the dominant species composition. They define five classes of upland (generally outside enclosures) scrub: 1. Wet Soils in Forest Zone: Salix spp., Carr open water transitions and mires; in wetter northern parts; Salix phylicifolia – N. England usually along river banks, Upper Teesdale along rivers. 2. Dry soils in Forest Zone: Dominated by Crataegus monogyna, with P. spinosa, Salix cinerea, Corylus avellana, Sorbus aucuparia, Malus sylvestris; usually occurs as discrete patches on freely draining brown earth or brown podzolic soils on steeper slopes and upland pastures.
93 3. Tree line scrub and scrub woodland: trees: Betula spp., Corylus avellana, Quercus spp., Populus tremula, Sorbus aucuparia, Pinus sylvestris - in wind pruned forms 4. Upland Juniperus to >650 m, two species lead to different vegetation types, but only one occurs in England and Wales; Juniperus communis ssp. communis W19 (with O. acetosella) - patchy spatial structure with open areas and thickets; few other woody species (scattered Betula pubescens); open areas - dwarf shrubs, ferns, herbs, bryophytes. 5. Betula nana – only found in the Highlands of Scotland.
Juniper
Two species of Juniperus occur in Britain, but only Juniperus communis ssp. communis is found in England and Wales. In upland areas it is found on free-draining soils that are kept moist by some flushing or by a northerly aspect (Rodwell, 1991a). Juniperus is largely found in Scotland, but scattered populations remain in northern England and Wales (Clifton et al., 1995), where its distribution is concentrated in the north Pennines. Populations range from isolated individuals to dense stands. In Upper Teesdale, Juniperus occurs most frequently close to farms, where inbye borders unenclosed land, and along side streams. It is found in a range of situations, on uneven ground, steep banks, scree slopes and cliffs (Gilbert, 1980).
Juniperus scrub is naturally a seral community before woodland and is rapidly shaded out by dense canopies (Anon., 2001f). It is, therefore, maintained because grazing inhibits succession to climax woodland (Mortimer et al., 2000). However, at high altitudes the absence of other trees and shrubs suggests that Juniperus is a climax community (Gilbert, 1980). In Teesdale it is associated with a range of species including grasses and ericoids (Ratcliffe, 1978), however the field layer can be diverse, and ungrazed stands may have rich fern communities (Clifton et al., 1995; Gilbert, 1980).
Several studies have investigated the dynamics of Juniperus. The processes that maintain populations are apparently complex and are discussed in section 3.6.
Woodland
Ancient or semi-natural woodland is widespread, but covers only a small proportion of the land area in the uplands. For example, semi-natural broad-leaved woodland covers only 0.9% of the Yorkshire Dales National Park (Graham & Dalton, 1993). Woods are usually small, generally less than 20 ha, and two out very three broad-leaved woodlands in the Yorkshire Dales were less than 4 ha (Graham & Dalton, 1993). At the hill-edge these woodlands are often restricted to inaccessible areas such as steep valley sides, ravines and screes (Institute of Terrestrial Ecology, 1978; Francis et al., 1989). They are rarely found above 350 m, although scattered trees occur at high altitudes along gills, which could be used as a framework for restoring ancient tree lines (Backshall et al., 2001). In winter, they provide valuable shelter for stock, deer and rabbits and are thus often subject to overgrazing (CEAS Consultants Ltd & Wye College, 1993a). Most semi-natural woodlands are broad-leaved, but mixed or coniferous stands are locally important. Quercus spp., Betula spp. and Fraxinus excelsior are the main species which dominate upland woodland, with Alnus glutinosa, Salix cinerea and Betula pubescens in wetter areas, on marshy ground or along rivers and spring lines.
Coniferous plantations occupy a much larger area and often cover a significant land area at the hill-edge, where acid grassland, heathland broad-leaved woodland have been replaced by
94 conifers. In a survey of common land in Ceredigion, Francis et al., (1990) recorded 9% of the land area as woodland, but more than 75% of this was conifer plantation. Non-native species are closely planted in single species blocks, and shade out other plants resulting in particularly species poor habitats with little wildlife value. Very locally, some botanical interest may remain in coniferous plantations. In mature coniferous stands, a ground layer typical of broad-leaved woodlands can persist (Graham & Dalton, 1993), and Francis et al. (1990) recorded botanically rich rides, particularly where a high water table resulted in stunted growth of conifers. In Dartmoor, the Red Data Book species Erica ciliaris, has been found in conifer plantations (Dartmoor Biodiversity Steering Group, 2001).
In broad-leaved woodlands, overgrazing results in an impoverished ground flora and a lack of regeneration of trees resulting in poor structure. Vigorous regeneration only occurs in fenced areas or on inaccessible slopes (Graham & Dalton, 1993). However, where grazing is limited, woodlands often have a rich herb layer, with abundant bryophytes and lichens (Dartmoor National Park Authority, 2002) some of which are rare or notable species (e.g. Jamesionella autumnalis, Graphina pauciloculata: Dartmoor Biodiversity Steering Group, 2001).
Oak
Quercus spp. are the most common species in upland broad-leaved woodlands (Institute of Terrestrial Ecology, 1978) and are found in all upland areas. However, it has been estimated that 30 to 40% have been lost over the past 60 years due to conifer planting, conversion to rough grazing and quarrying and other development. Currently only 70 000 to 100 000 ha of upland Quercus woodland remain, concentrated in Gwynedd, Devon, Cornwall and Cumbria (Anon., 1995c). Quercus woodlands are largely confined to the upland fringes often on steep valley sides (Jerram et al., 1998). They occur on a range of soils, usually base poor to acidic. These woodlands are sometimes found on limestone, but only in areas of high rainfall where significant leaching occurs (Institute of Terrestrial Ecology, 1978). Overgrazing is now the most important factor threatening these communities, but Rhododendron spp. invasion, air pollution (lichens and bryophytes) and development may also be locally significant (Anon., 1995c).
Quercus spp. (more commonly Q. petraea: Institute of Terrestrial Ecology, 1978) and Betula spp. are the dominant species with varying amounts of Ilex aquifolium, Sorbus aucuparia and Corylus avellana in the understorey. In less acidic areas, Fraxinus excelsior and Ulmus glabra are also present (Anon., 1995c). The field layer is often species poor, however, western oakwoods are of international importance for bryophytes which thrive in the more oceanic areas because of high rainfall and the suppression of shrub and field layers by grazing (Backshall et al., 2001). They also support many lichens such as Parmelia spp. and Usnea spp., and include some uncommon species such as Graphina pauciloculata, Graphina ruiziana and Pannaria sampaiana (English Nature & Dartmoor National Park Authority, 2001). Some Quercus woodlands also support a rich fern flora, including Gymnocarpum dryopteris, Phegopteris connectilis and Hymenophyllum spp. (Kelly & Perry, 1990). Species composition of the field layer is variable, depending on the local soil type and grazing and can be dominated by Hyacinthoides non-scripta and Rubus fruticosus, grasses, Pteridium or mosses. Hyacinthoides non-scripta, Conopodium majus and Dryopteris dilatata are common under all oakwoods. Deschampsia flexuosa, Vaccinium myrtillus and Pteridium tend to predominate on the most acid soils (Kelly & Perry, 1990). Within oakwoods, more species rich communities occur on more alkaline soils that are often associated with streams. In these
95 areas, species such as Allium ursinum, Mercurialis perennis and Circaea lutetiana are more common (Anon., 1995c).
Four NVC communities are dominated by Quercus spp. (Table 4.15). W10 Quercus robur – Pteridium aquilinum – Rubus fruticosus is widely distributed across England and Wales. This community is more common in lowland areas and is replaced at higher altitudes by W11 Quercus petraea – Betula pubescens – Oxalis acetosella, which is found in the upland fringes of Wales and North West England. W16 Quercus spp. – Betula spp. – Deschampsia flexuosa is a community of very acidic and oligotrophic soils, found largely in the Pennine fringes. W17 Quercus patraea – Betula pubescens – Dicranum majus is distributed through the wetter areas of north western Britain, with particularly good stands found in Mid- and North-Wales and the Lake District (Rodwell, 1991a).
Ash
Woodlands dominated by Fraxinus excelsior are more species rich than oakwoods. They occur on base rich soils that are characteristic of limestone areas often on steep slopes where soils are shallow. They also occur on rocky outcrops and screes where calcareous rocks are exposed and along local flushes associated with streams and spring lines often within stands of Quercus spp. on more acidic substrates (Institute of Terrestrial Ecology, 1978). Fraxinus woodlands are found throughout upland regions of England and Wales. They generally exist as small stands except on calcareous substrates, such as the carboniferous limestone of the Pennines (Rodwell, 1991a). However, significant areas of Fraxinus woodland have been lost over the past 50 years because of clearance, overgrazing and coniferous plantations (Anon., 2001b).
In these woodlands, Fraxinus excelsior dominates the canopy with Ulmus glabra, Corylus avellana, Betula spp., Sorbus aucuparia, Quercus spp. and Acer pseudoplatanus (Rodwell, 1991a). However, the presence of Quercus spp. is very variable in northern and western areas and they are virtually absent from the Yorkshire Dales (Drewitt, 1991). This may be because they failed to re-establish after early clearance (Rodwell, 1991a). Rare tree species such as Tilia platyphyllos and whitebeams (Sorbus spp.) are also found in Fraxinus woodlands (Anon., 2001b). Corylus avellana and Crataegus monogyna are the most common species of the shrub layer. A wide variety of vascular plants contribute to the field layer in these woodlands including: Mercurialis perennis, Hyacinthoides non-scripta, Geum urbanum, Circaea lutetiana, Viola riviniana, Brachypodium sylvaticum, Geranium robertianum and Veronica montana (Rodwell, 1991a). Montane species that occur locally in Fraxinus excelsior woods include Rubus saxatilis and Cirsium heterophyllum (Drewitt, 1991). Rare woodland species that are found largely in upland ashwoods include Epipactis atrorubens, Polemonium caeruleum and Polygonatum verticillatum (Anon., 2001b). Fraxinus excelsior woodlands also support rich fern communities, particularly at higher altitudes where Dryopteris spp. and Athryium filix-femina are abundant (Rodwell, 1991a).
Currently, the greatest impact on these woodlands is grazing which limits regeneration of woody species and reduces the diversity of the ground flora. Other factors include invasion by Acer pseudoplatanus and Fagus sylvatica, changes in structure and species composition with the loss of Ulmus glabra to Dutch elm disease, and quarrying of carboniferous limestone (Anon., 1995c).
96 Fraxinus excelsior is a dominant species in two NVC communities associated with the hill- edge (Table 4.15). W8 Fraxinus excelsior – Acer campestre – Mercurialis perennis is a community common in the lowlands which extends into upland areas. It is replaced at higher altitudes by W9 Fraxinus excelsior – Sorbus aucuparia – Mercurialis perennis woodland which is often found in small stands in response to local flushing (Graham & Dalton, 1993). Tilia cordata, has a local distribution and is found associated with the W9 community in parts of the Lake District (Rodwell, 1991a).
Wet Woodland
Woodlands dominated by Salix cinerea, Alnus glutinosa and Betula pubescens occur in wetter areas, with Alnus woodlands particularly important in Wales (Institute of Terrestrial Ecology, 1978). These communities have developed from scrub on marshy grassland and wet heath and are also found as small stands on wet areas within woodlands dominated by other species, associated with rivers, spring lines and lakes (Institute of Terrestrial Ecology, 1978). Three NVC communities are represented at the hill-edge: W1 Salix cinerea – Galium palustre, W4 Betula pubescens – Molinia caerulea and W7 Alnus glutinosa – Fraxinus excelsior – Lysimachia nemorum (Table 4.15).
Table 4.15. Woodland communities associated with the hill-edge Community Comments W1 Salix cinerea – Galium palustre W4 Betula pubescens – Molinia caerulea Widespread but local on upland fringes Typical of moist moderately acidic peaty soils W7 Alnus glutinosa – Fraxinus excelsior – Widespread but local on upland fringes of north and west Lysimachia nemorum Typically in narrow bands along rivers and spring lines W8 Fraxinus excelsior – Acer campestre – Base rich soils at least in lower horizons Mercurialis perennis Replaced by W9 at higher altitudes W9 Fraxinus excelsior – Sorbus aucuparia – Submontane zone of the north west typical of upper reaches Mercurialis perennis of valleys Moist soils derived from calcareous bedrocks W10 Quercus robur – Pteridium aquilinum – Replaced by W11 at higher altitudes Rubus fruticosus W11 Quercus petraea – Betula pubescens – Moist but free-draining base-poor soils Oxalis acetosella Generally on upper slopes 1 W13 Taxus baccata Infrequent in upland areas Found on steep usually south facing limestone slopes 1 W16 Quercus spp. – Betula spp. – Pennine fringes Deschampsia flexuosa Acidic free draining soils 1 W17 Quercus petraea – Betula pubescens – Widespread on upland fringes of north and west Dicranum majus Information from Rodwell, 1991a 1 Graham & Dalton, 1993.
Linear features
Linear features are not considered in detail here, but are discussed briefly because they may be important within the habitat mosaic. Field boundaries are characteristically different across the upland regions of England and Wales, from hedges dominated by Fagus sylvatica in Exmoor to the walled enclosures of the Pennine Dales and Lake District.
Walls provide important niches for mosses and lichens and the characteristic walled banks of Dartmoor support a distinctive range of species. Walls have been lost with increases in field
97 size and through neglect; Hayes et al. (2001) estimated that 25% of Welsh hedges had been lost during the 1980s because of neglect, particularly in the upland fringe. The replacement of walls with wire fences has been widespread and has resulted in a loss of habitat. However, fences themselves aid the establishment of a range of woody species, such as Sorbus aucuparia, Crataegus monogyna and Juniperus, by providing bird perches (Institute of Terrestrial Ecology, 1978).
Summary
x Grassland types occurring on the hill-edge include acid and calcareous unimproved rough grazings, semi-improved or semi-natural mesotrophic grasslands, wet grassland dominated by rushes and sometimes improved pasture or hay meadows interspersed with more typical hill-edge habitats. x Acid grassland is the most common hill-edge habitat. They are generally species-poor and dominated by Molinia carulea and Nardus stricta, though some areas are species rich, particularly for bryophytes and club-mosses. The main NVC communities are U4 Festuca ovina - Agrostis capillaries - Galium saxatile and U5 Nardus stricta - Galium saxatile. Others are U2 Deschampsia flexuosa, U2b Vaccinium myrtillus sub- community, and U3 Agrostis curtisii. x Semi-natural mesotrophic grasslands are rare, because they are readily improved, but a range of mesotrophic grasslands improved to varying degrees can occur on the hill- edge. NVC communities include MG3 Anthoxanthum odoratum – Geranium sylvaticum and the MG3a Bromus hordaceus ssp. Hordaceus sub-community, MG6a Lolium perenne – Cynosurus cristatus, and the MG6b L. perenne – C. cristatus, Anthosanthum odoratum sub-community, MG8 Cynosurus cristatus – Caltha palustris, MG9 Holcus lanatus – Ceschampsia cespitosa, and MG10 Holcus lanatus – Juncus effusus. MG3 is restricted to traditional hay meadows in upland England, but other mesotrophic grasslands are more extensive in lowland areas. x Calcareous grasslands cover a much smaller area than acid grasslands, but are more species-rich and include many rare and uncommon species. NVC communities include CG9 Sesleria albicans – Galium sterneri, CG10 Festuca ovina – Agrostis capillaris – Thymus praecox, CG2c Festuca ovina – Avenula pratensis, and small areas of CG7 Festuca ovina – Heracium pilosella – Thymus praecox/pulegioides grasslands. The sugar limestone grasslands of Upper Teesdale have a particularly high botanical interest, with a number of species found nowhere else. x Rocky areas, e.g. rock outcrops, scree, tors and limestone pavements, may be botanically important for pioneer species but also form important refuges for species susceptible to grazing, and in consequently in some areas have high conservation value. x Metalliferous communities occur on mining spoil in northern England and in some areas give rise to communities with high botanical interest. Only one NVC community is recognised, OV37 Festuca ovina – Minuartia verna. x A range of communities associated with wet areas on both acid and base-rich soils occur on the hill-edge. They may cover large areas or be restricted to local flushes, and often occur in mosaics with other communities. Wet acid grasslands tend to be species- poor with dominant species ranging from Molinia caerulea in dryer areas through Juncus spp. to sedges and Sphagnum mosses in the wettest areas. The commonest NVC communities of acid wet areas are M23 Juncus effusus/acutiflorus – Galium palustre, M6c Carex echinata – Spagnum recurvum/ariculatum, Juncus effusus sub-community, and M25 Molinia caerulea – Potentilla erecta. M21 Narthecium ossifragum –
98 Sphagnum papillosum also occurs on the moorland fringes in some areas. Base-rich flushes tend to support a wider range of species. Two NVC communities have been recognised: M26 Molinia caerulea – Crepis paludosa and M10 Carex dioica – Pinguicula vulgaris. x Bracken (Pteridium aquilinum) occurs over large areas, especially in the west of Britain, and is often the dominant species, representing an important vegetation type of the hill-edge. Because of the dense shade it produces, bracken stands are generally species poor. Agriculturally it is considered a weed and large areas have been subject to control measures, though success is often limited. At a local scale, bracken stands may be botanically valuable, and provide habitat for some bird and invertebrate species of conservation concern. x Dwarf shrub heath vegetation, usually dominated by Calluna vulgaris, are internationally important communities generally typical of open moorland, but also found on the hill-edge. They are generally species-poor, though they can be very rich in bryophytes and lichens. NVC communities include H4 Ulex gallii – Agrostis curtisii, H8 Calluna vulgaris – Ulex gallii, H12 Calluna vulgaris – Vaccinium myrtillus, H9 Calluna vulgaris – Deschampsia flexuosa, H10 Calluna vulgaris – Erica cinerea, H18 Vaccimium myrtillus – Deschampsia flexuosa, and H21 Calluna vulgaris – Vaccinium myrtillus – Sphagnum capillifolium. x Scrub is a climax community at the limits of altitude or exposure, but is more often a seral community where grazing pressure has been reduced. Although common on the hill-edge, it generally occurs in small and scattered fragments, many of which are not regenerating. Although often considered of low value and as an indicator of dereliction, it is an important habitat and an increase in scrub would bring conservation benefits. NVC communities include W19 Juniperus communis ssp. communis – Oxalis acetosella, and W23 Ulex europaeus – Rubus fruticosus. Juniper scrub has a particular conservation value, and occurs in scattered stands in England and Wales, particularly the north Pennines. x Ancient or semi-natural woodlands are widespread, but usually occur in small pockets in inaccessible areas. They often suffer from overgrazing and consequently suffer from lack of regeneration and an impoverished ground flora. In contrast, coniferous plantations often occupy large areas but are generally of little botanical interest. On base-poor and acidic soils, oak Quercus sp. (usually Q. patraea) is the dominant tree species of broadleaved woodland, the NVC communities being W10 Quercus robur – Pteridium aquilinum – Rubus fruticosus, W11 Quercus patraea – betula pubescens – Oxalis acetosella, W16 Quercus spp. – Betula spp. – Deschampsia flexuosa, and W17 Quercus patraea – Betula pubescens – Dicranum majus. On base-rich soils, more species-rich ash (Fraxinus excelsior) – dominated woodlands occur. Two ash- dominated NVC communities are found on the hill-edge: W8 Fraxinus excelsior – Acer campestre – Mercurialis perennis and W9 Fraxinus excelsior – Sorbus aucuparia – Mercurialis perennis. In wet areas, woodlands dominated by Salix cinerea (W1 S. cinerea – Galium palustre), Betula pubescens (W4 B. pubescens – Molinia caerulea), and Alnus glutinosa (A. glutinosa – Fraxinus excelsior – Lysimachia nemorum) are found. x Linear features in the uplands include walls, fences and hedges. Walls are characteristic and can support a distinctive range of plant species, but many have been lost or damaged through increases in field size or neglect.
99 Vegetation Changes in Response to Management
This section summarises the effects of grazing, improvement and reversion on species composition of all habitats discussed in this review. The impact of burning is not discussed specifically here because this practice is more often associated with heathland, although it does exacerbate the effects of grazing (Dixon, 1984). Afforestation has had marked impact at the hill-edge, with significant areas of land lost to coniferous plantations during the 20th century. Botanical changes resulting from afforestation are, therefore, also briefly considered. Finally, changes in Pteridium and Juniperus are discussed separately because some factors affecting their population dynamics are species specific.
Grazing
The impact of grazing on species composition of the vegetation in upland habitats has been the subject of many studies, which have discussed successional changes in detail (e.g. Armstrong & Milne, 1995: Hill et al., 1992: Institute of Terrestrial Ecology, 1978: Ball et al., 1981) although they have often concentrated on dwarf shrub heath or grass moorland communities.
Intensive management by either grazing or burning can shift the vegetation composition of some areas from an intricate mosaic of habitats to a situation dominated by one or two vegetation types (Hudson, 1989). However, grazing is important in the maintenance of many semi-natural habitats and greatest diversity of species composition and structure is likely to be achieved under light or moderate grazing (Fuller & Gough, 1999). For example, in the absence of grazing in Upper Teesdale, Sesleria caerulea becomes dominant and suppresses many less competitive species. However, some species will only flower in the absence of grazing e.g. Saxifraga hirculus and Alopecurus alpinus (Cadbury, 1999). Some grazing is required to maintain populations of Juncus squarrosus that can be outcompeted in the absence of grazing or at low grazing pressures (Anderson & Radford, 1994). Increased grazing of Agrostis/Festuca swards on acidic soils led to the development of bryophyte rich communities, with Pleurozium schreberi, Rhytidiadelphus spp. and Hypnum cupressiforme (Ball et al., 1981).
Grazing and burning may result in the replacement of dwarf shrub heath with grasses. The presence of Vaccinium myrtillus indicates a transition between Calluna vulgaris and acidic grassland, and may represent the first stages of degradation (Coulson et al., 1992). In dry conditions, Festuca ovina, Agrostis spp. and Deschampsia flexuosa dominate although Pteridium can also invade as a result of overgrazing. In wetter areas Nardus stricta becomes the dominant species and where conditions are very wet grazing leads to an increase in the density of Juncus squarrosus (Ratcliffe, 1978; Dixon, 1984) on poached or overgrazed areas (Miller et al., 1984).
Ball et al. (1981) reported changes in species composition within grasslands in response to grazing and fertiliser applications. In a sward of Festuca/Nardus/Molinia, increased grazing resulted in decreased Molinia caerulea populations, and increased Poa spp. and Agrostis spp. populations were probably a result of grazing and fertiliser applications. Exclusion of grazing from a Festuca/Nardus/Vaccinium sward led to an increase in Molinia caerulea and ericaceous species, but to a decrease in Nardus stricta. Holcus spp., Deschampsia cespitosa and Deschampsia flexuosa increased in Festuca/Agrostis swards when grazing was excluded,
100 but light-demanding species including Juncus squarrosus, Cerastium holosteoides, Minuartia verna, Thymus drucei and Viola spp. declined.
Grazing can have a profound effect on vegetation, with the results depending on: x the palatability of the vegetation x susceptibility of species to grazing x species of grazer x stocking density x time of year x period of grazing x availability of other food sources.
Many of these factors are interlinked, but the following is an attempt to summarise the important factors.
Palatability
Sheep will selectively graze more digestible species such as Festuca spp. and Agrostis spp. They avoid Nardus stricta and Molinia caerulea that are of less nutritional value except in spring when new growth is available. They eat ericaceous species only when other food is unavailable, but graze Vaccinium myrtillus preferentially to Calluna vulgaris and this in turn to Erica cinerea (Dixon, 1984).
Susceptibility
Habitats such as woodland, scrub and mires have a low resistance to grazing (CEAS Consultants Ltd & Wye College, 1993a), because many of the species present are particularly susceptible to damage or defoliation. Studies of susceptibility have concentrated on woody species where the lack of regeneration has been blamed on grazing. However, Hester (1996) points out that woodland studies usually compare no grazing with very high grazing pressure. Some grazing of woodland may be important to open up the field layer and create localised soil disturbance. However, Hester & Miller (1995) recorded a negative relationship between tree regeneration and sheep densities, although few studies have looked at the impact of other grazers.
Some woody species are more vulnerable to grazing pressure that others. The Institute of Terrestrial Ecology (1978) ranks species thus: very – Tilia spp., Ulmus spp., Betula spp., Salix spp., Alnus glutinosa fairly – Acer pseudoplatanus, Abies alba, Quercus spp., Sorbus aucuparia, Fraxinus excelsior, Fagus sylvatica, Thuja plicata not so – Pinus spp., Ilex aquifolium, Crataegus monogyna, Larix spp., Taxus baccata, Conium maculatum, Picea abies least – Picea sitchensis
101 Stock species
The grazing characteristics of stock (and wild) species are different and this can significantly affect the impact of grazing on a sward. The relative selectivity of different animals is:
less selective more selective cattle > deer, horses > sheep > goats, rabbits, voles
Sheep bite the vegetation and are selective grazers. This type of grazing leads to the spread of unpalatable grasses. Sheep graze Agrostis spp., Festuca spp., Deschampsia flexuosa and L. perenne preferentially because these species are relatively digestible (Hester, 1996). However, Nardus stricta, Molinia caerulea, ericoid species and Juncus spp. are generally avoided, although Molinia caerulea populations often increase where grazing is excluded (Ball et al., 1981). Wethers (castrated rams) are believed to be less selective and will eat Nardus stricta, Molinia caerulea and Juncus spp.. Wethers thereby apply a certain level of control on these species (Hill et al., 1992). Before 1900, wethers were overwintered on the hill, leading to intense grazing in late winter and spring. However, during the 20th century there was a significant reduction in wether numbers because of the decreasing popularity of mutton and the fact that CAP support payments are based on ewe numbers. This has meant that overwinter grazing has been reduced and grazing has generally been more selective leading to a decline in the grazing quality of many upland swards.
Cattle are less selective grazers rolling their tongue around and pulling at vegetation (Dixon, 1984). They have a greater ability than sheep to digest poor quality vegetation, because they have a larger gut. Cattle are, therefore, more likely to eat species which are less palatable, such as Nardus stricta and Molinia caerulea, and are thus more effective than sheep at controlling populations of these grasses (Backshall et al., 2001). Cattle will also graze Juncus spp. and, at relatively high stocking densities, can keep Juncus populations under control (Hester, 1996) without eliminating these species from the sward (Backshall et al., 2001). Cattle also create more disturbance producing uneven swards (Aitchison & Medcalfe, 1994). Herds of suckler cows may therefore have a beneficial effect on upland rough grazings but, in recent decades, cattle have been replaced by sheep response to economic forces affecting upland farming.
Goats are not common in upland areas, but are very selective feeders and may have significant impacts on vegetation at a local level. Because they are browsers, goats have a severe effect on woody species. As goats are much better climbers than sheep, they are also a threat to communities that are restricted to inaccessible rocky areas (Hester, 1996).
Stocking density
Overgrazing is a threat to many habitats or to the balance of species within them. Sheep numbers in the uplands increased dramatically during the 1970s and 1980s although there was considerable local variation (Fuller & Gough, 1999). Despite the introduction of stocking density restrictions on CAP payments, sheep numbers have remained significantly higher than they were 30 years ago. Greatest attention has been focussed on dwarf shrub heath communities, where overgrazing eventually eliminates ericoid species which are replaced by coarse grasses. However, excessive stocking densities will significantly alter the species composition of all swards. Woodland and scrub regeneration is severely restricted and the lack of seedlings and saplings in many upland woodlands is evidence of this. Excessive
102 grazing pressure often restricts sensitive communities to inaccessible areas including steep slopes and rocky outcrops and Pteridium stands influence the accessibility of sites and therefore act as a canopy substitute for woodland species of the field layer and a nurse crop for woody species. High stocking densities can also have an impact on the vegetation by altering the physical environment. Juncus spp. infestations can occur as a result of poaching and severe trampling of swards (Backshall et al., 2001).
Time of grazing
The farming system will have a significant effect on the vegetation characteristics through both the timing of grazing and the period of time during which vegetation is grazed. Generally plants are most susceptible to grazing in spring and autumn (Backshall et al., 2001). However, where animals graze preferentially on selected species at certain times of year, the impact of grazing can be very different. Calluna vulgaris is an important food source for sheep during the winter in the absence of more palatable grazing, despite its relatively low nutritional value at this time of year (Cadbury, 1999). Hardy breeds of sheep, suited to upland conditions are left on the hill for much of the winter and supplementary feeding allows animals to be left out longer and at higher densities (Backshall et al., 2001). This practice means that Calluna vulgaris is vulnerable to excessive grazing pressure and that feeding sites where animals congregate can develop into localised areas of degraded habitat.
Availability of other food
Animals that feed on selected species will tend to avoid other species where sufficient stocks of the preferred species are available. However, during winter, or at high stocking densities, stock and other animals will eat a wider range of species. Ericaceous species are usually only eaten in the winter when grass forage is limited (Armstrong & Milne, 1995). Nardus stricta and Molinia caerulea are generally avoided by sheep, except where grazing pressure is high and other sources of food are limited or in early spring when new growth is available.
Improvement
Semi-natural vegetation may be improved by a range of methods including ploughing and reseeding, drainage, burning, cutting, the application of fertiliser (artificial and organic manure) lime or slag and the use of herbicides. Sites with the greatest agricultural potential have been lost to improvement (e.g. Festuca/Agrostis swards which respond to improvement), whilst conifer plantations have been established on less productive areas such as acid grasslands (Wathern et al., 1988) and mires dominated by Molinia caerulea (Rodwell, 1991b). Common lands often escaped significant improvement because agreement from all rights holders was necessary. Common land therefore supports a significant proportion of semi-natural relatively unimproved land (Penford & Francis, 1990).
Improvement is a major factor on inbye land and generally leads to a loss of species and habitat diversity, with fewer small-scale mosaics of vegetation such as wet flushes (CEAS Consultants Ltd & Wye College, 1993a). In a comparison of improved and unimproved swards in the uplands, Baines (1988b) recorded reduced soil moisture, decreased homogeneity of vegetation structure, a decline in the number of species, a decrease in organic matter and an increase in pH on improved land. Silage production has become popular because it produces a better quality feed and production is less dependent on weather conditions (Backshall et al., 2001). However, the change from hay to silage has reduced the
103 species diversity of inbye land significantly with earlier cutting eliminating the possibility of seed set for many typical hay meadow species. Greater fertiliser inputs also have an impact on species diversity, but additionally result in more fast growing, nutrient demanding species such as Rumex spp. and Cirsium spp. (CEAS Consultants Ltd & Wye College, 1993a).
In a study of enclosed upland areas between 1970 and 1986, Hopkins & Wainwright (1989) recorded that most swards, which contained forb species, had received little or no artificial nitrogen inputs. Most forbs were found in older swards with 80% of species recorded where no improvement had occurred for more than 20 years.
Reversion
The intensity of improvement in upland areas has slowed with the shift in emphasis towards environmental concerns and the curtailment of specific grants for improvement (e.g. liming grants which were stopped in the 1970s (Mowle & Bell, 1988)). In a survey of botanical changes between 1970 and 1986 in swards in enclosed fields from seven upland areas in England & Wales, Hopkins et al. (1988), reported increasing age of upland swards, particularly on more marginal fields. Eighty two percent of grassland that was over 20 years old at the first survey had not been reseeded by the mid 1980s, and reseeding of older grassland above 360 m was extremely rare. Many more marginal fields that received some improvement have since reverted to rough grazing (Dixon, 1987), and older improved swards have reverted to bracken, scrub or heathland (Walters Davis & Davis, 1973). Reversion will proceed at different rates depending on many factors including management, drainage and the availability of seed sources.
Hopkins et al. (1988) reported rapid losses of Lolium perenne cover after reseeding in a survey of seven study sites in England and Wales. On 30% of swards aged between five and eight years Lolium perenne represented less than 40% of the sward, whereas on very recently reseeded swards, this species accounted for 80% of the vegetation cover. Poa spp., Agrostis spp. and Festuca spp. all replaced Lolium perenne over significant areas, but Holcus lanatus, Cynosurus cristatus, Anthoxanthum odoratum and Deschampsia cespitosa were also present particularly in older swards. At higher altitudes Nardus stricta, Molinia caerulea, Deschampsia flexuosa, Eriophorum spp. and Carex spp. were also present although these species did not generally form a significant part of the vegetation.
In a study of management on hill pastures reclaimed 20 years previously in mid Wales, Davies (1967) reported significant differences in species composition depending on management. Drainage was a particularly important factor and well-drained fields had the least reverted swards with Lolium perenne and Trifolium repens dominant. Where drainage had been inadequate, most sown species were absent and swards were dominated by Juncus effusus, Agrostis spp. and Holcus lanatus with dicotyledonous weed species also present. Undergrazing during the summer led to reversion of the sward, but this was limited where lime application had continued. Cutting of thistles and rushes had no lasting effect.
Agrostis spp. increased with decreasing intensity of management, increased with altitude and populations were higher under grazing than cutting. Juncus spp. were present in 22% of grasslands usually at relatively low levels and concentrated on older swards with poor drainage. Pteridium was frequently recorded at low levels, particularly on steep slopes but none was found on land that had been grazed by cattle. Trifolium repens decreased with increasing soil nitrate, altitude and soil moisture. Festuca spp. increased at higher altitudes
104 and in older swards. Several species were more frequent where only sheep had grazed, including Cirsium arvense, Agrostis spp., whereas Rumex spp. were more common under cattle grazing. Ericoid species were recorded in only a few rough grazings.
In a study of methods to enhance botanical diversity in upland grassland, Hayes et al. (2000a) looked at different cutting/grazing regimes and lime applications on agriculturally improved MG6/7 swards in mid-Wales. A control treatment consisted of regular fertiliser inputs, periodic lime applications and grazing. Grazing was compared with a hay cutting treatment and a hay cutting treatment followed by aftermath grazing and these treatments were combined with plus/minus lime applications at the start of the study. Additionally, seed was added to small areas of the plots to determine whether seed availability was a limiting factor in the rate of reversion. Their major findings were: x Reversion from a very improved sward was rapid with significant losses of Lolium perenne populations. Grazing alone resulted in an approximately 60% loss of Lolium perenne cover in four years, but hay cutting accelerated this decline. Agrostis capillaris was the most common species to replace Lolium perenne in the sward reflecting a rapid decline in soil fertility in the absence of fertiliser inputs. x Grazing was important in increasing the number of forb species in the sward, because defoliation in the autumn and winter prevented coarse grasses from dominating the sward and soil disturbance created suitable sites for germination. x The effects of liming were not significant but, although lime applied in the early years may have maintained fertility to some degree, a greater number of forbs were recorded on limed treatments and light or infrequent lime application was required to avoid acidification. x A hay cut followed by aftermath grazing encouraged the greatest species diversity and reversion from a highly improved sward and change was rapid. However, after three years, community composition of swards was still close to MG6b with some shift to MG5 or U4b.
Afforestation
Afforestation with non-native conifers has probably had the greatest affect on hill-edge habitats, particularly during the second half of the 20th century. Conifer plantations have a profound effect on the understorey vegetation. Generally, few species of vascular plants survive under extreme conditions of low light availability and dense leaf litter after canopy closure. However, more varied ground flora may persist in open rides (Francis et al., 1990) or where conifer establishment or development is poor, particularly in badly drained areas.
In a study of changes immediately after afforestation, Sykes et al. (1989) reported little change in species richness in the short term after planting, although there were significant changes in community composition. The removal of intensive grazing by stock species allowed the proliferation of Molinia caerulea and Deschampsia cespitosa. However, drainage probably led to the decline of Eriophorum vaginatum and Eriophorum angustifolium. Ploughing provided suitable germination sites for species with persistent seed banks such as Agrostis capillaris and Juncus spp.. A long-term study of afforestation reported an increase in ferns and mosses, but a corresponding decrease in forb species and abundance over 30 years (Hill & Jones, 1978). Declines in species number were particularly important under dense coniferous stands.
105 Bracken
Pakeman et al. (1996) estimated that approximately 4.5% of marginal upland land was dominated by Pteridium in 1990. The land area covered by Pteridium has increased over the past few decades and in some areas this trend is apparently continuing, although estimates of change between the 1970s and 1980s suggested that overall Pteridium increased only in the Brecon Beacons (Pakeman et al., 1996). However, estimates of change can be misleading because of large-scale changes in land use. Coniferous plantations are commonly located on marginal upland areas and, because Pteridium is generally found on well-drained soils, they are suitable for improvement. In a survey of farmers' perceptions in 1991, 56% believed that Pteridium distribution had changed over the past 10 years, but that it was not spreading in all areas of England and Wales. Indeed there was an apparent decline in parts of Wales, presumably because of the sustained control efforts (Varvarigos & Lawton, 1991). Increases in Pteridium have occurred over the past 30 years, despite efforts to control it, as a result of changes in management, increased nutrient deposition, drainage of moorland and due to the recent warmer seasons because Pteridium is close to its climatic limit (Hetherington & Anderson, 1998). The ecology and distribution of Pteridium, strategies to control it and methods of sustainable management have been intensively studied (e.g. Pakeman et al., 1997; Pakeman et al., 1996; Pakeman et al., 2000; Marrs et al., 2000; Pakeman et al., 1995). The following is a brief summary of management practices that indirectly affect Pteridium populations. However, Pakeman et al. (2000) point out that the reasons for Pteridium expansion and the impacts of grazing management are poorly understood.
Brown (1986) outlined the major management practices that potentially cause the expansion of Pteridium: x burning x reduced cutting x clear felling of woods x decreased intensity of agriculture
Burning may give Pteridium a competitive advantage over heather, particularly if it is poorly managed or too frequent. Burning is carried out over winter when dormant Pteridium rhizomes escape damage below the soil surface (Ward, 1972) whilst growth of woody vegetation is initially retarded (Miller & Miles, 1984).
Until the 1950s large quantities of Pteridium were cut for bedding, fuel, thatch, compost and as a source of potash (Hudson, 1988), and contributed to keeping populations under control. Though ‘estover’ rights remain on some commons, Pteridium is rarely cut nowadays.
Pteridium is essentially a woodland species that has thrived as a result of deforestation. Current clear felling of woodland therefore potentially leads to the domination of Pteridium.
Decreased intensity of agricultural management allows Pteridium to expand, particularly on marginal enclosed areas and increases have been observed on abandoned land around crofts (Hudson, 1988). Pteridium is often particularly important on common land (Varvarigos & Lawton, 1991) because of the difficulties of organising costly control measures many individuals have common rights (Penford & Francis, 1990).
106 There has been a reduction in cattle numbers in upland areas in recent years, in response to economic factors largely relating to CAP payments. This is also believed to have encouraged the expansion of Pteridium populations because cattle trample fronds and damage rhizomes particularly in spring when plants are more sensitive (Cotton & Hale, 1989), whereas sheep, which have replaced cattle in these areas, avoid Pteridium stands or do significantly less damage to the plants (Institute of Terrestrial Ecology, 1978).
Juniper
Juniperus is becoming scarce and populations in England and Wales are very localised. It has been listed under the EC Habitat and Species Directive as a habitat of European interest. The presence of Juniperus is one of the principal features of Moorhouse in Upper Teesdale, which is a candidate Special Area of Conservation (Clifton et al., 1995). Several factors affect the survival of Juniperus populations including inappropriate grazing levels, direct clearance or grazing or forestry, excessive burning, low economic and cultural value (Anon., 2001f). Erosion can also lead to the loss of Juniperus where plants occur in steep areas (Clifton et al., 1995).
Impact of Grazing
Grazing is the most important factor in the decline of Juniperus (Clifton et al., 1995). It is resistant to moderate grazing pressure because mature plants are avoided by stock. However, excessive grazing can ultimately destroy even dense stands and Gilbert (1980) suggests that the decline on limestone areas may be a result of high stocking rates. The impact of grazing animals is not restricted to stock. Juniperus is an important food source for rabbits that may also undermine the root system (Clifton et al., 1995). Grazing is particularly important in winter when Juniperus forms an important source of food and shelter whereas, in summer, when better grazing is available, it is generally avoided by sheep (Fitter & Jennings, 1975). Light grazing during the summer is in fact important because this reduces competition from the more palatable species that are grazed (Fitter & Jennings, 1975).
Regeneration
The exclusion of sheep has been shown to increase both the survival and the growth of young plants (Fitter & Jennings, 1975). However, this has not increased regeneration in some areas and few seedlings establish in these circumstances (Gilbert, 1980), whereas high seedling densities sometimes occur when grazing pressure is intense. This suggests that other factors are important in the regeneration of Juniperus.
Many stands are very even aged generally dominated by plants over 50 years old, with a notable lack of seedlings and young plants. Although individuals may survive for upwards of 200 years, the ability to reproduce decreases with age (Clifton et al., 1995). Seedlings are apparently associated with bare ground or short open swards and are often found on boulders or scree which are both inaccessible to grazers and present little competition from other species (Clifton et al., 1995). If they are severe, erosion events may destroy mature individuals but, in the long term, they may also perpetuate the survival of populations by providing suitable sites for germination and establishment. Similarly, fire may be important in the long-term survival of Juniperus (Clifton et al., 1995). In the past, Juniperus was cut and trees were probably dragged from the stand, thus creating bare ground suitable for
107 seedling establishment (Clifton et al., 1995). The exclusion of grazers alone is unlikely to improve regeneration, since closed swards prevent establishment (Backshall et al., 2001).
Establishment appears to occur most often where grazing pressure is variable (Clifton et al., 1995). Juniperus populations in the north of England are associated with mining areas, where fluctuating mining activity has meant that farming activity has also fluctuated. This change in intensity of grazing pressure over long periods of time is thought to have helped perpetuate Juniperus colonies. This is reflected in the widespread regeneration of Juniperus, which occurred during the 1950s after myxomatosis significantly reduced grazing activity (Fitter & Jennings, 1975).
Summary
x Management factors which can affect vegetation on the hill-edge include grazing (including species and density of stock and timing of grazing), improvement, reversion, and afforestation. x Grazing is necessary to maintain many semi-natural habitats, but heavy grazing is generally detrimental and can lead to the replacement of habitat mosaics with homogeneous vegetation dominated by relatively few species. Some species are intolerant of grazing and only persist where protected from it e.g. in rocky areas. x More palatable grass species such as Festuca spp. and Agrostis spp. are grazed selectively by sheep, whereas others tend to be avoided. The susceptibility of different species to grazing also varies. Cattle are the least selective grazers, followed by deer and horses, sheep, then goats, rabbits and voles. The replacement of cattle by sheep in recent decades coupled with high sheep stocking densities has led to a deterioration in the quality of vegetation with an increase in Nardus, Molinia and Juncus at the expense of more palatable grasses and dwarf shrubs. The decline in numbers of wethers in favour of the more selective ewes has also contributed to this trend. x Timing and period of grazing are also important. Generally, plants are most susceptible to grazing in the spring and autumn, but perhaps the most significant effect of timing has been the increase in winter grazing made possible by the use of supplementary feed. Feeding of sheep in winter on heather (Calluna vulgaris) stands has resulted in the degradation of the heather to grass moor over large areas. x Agricultural improvement by reseeding, drainage, burning, cutting, fertilising, liming and herbicide use generally leads to loss of species and habitat diversity. Changing from hay to silage also reduces species diversity through earlier cutting and greater fertiliser use. x The removal of incentives for agricultural improvement has reduced the rate of improvement in upland areas ion recent decades. Improved grassland reverts back towards vegetation more typical of rough grazing at a rate depending on management, particularly drainage. Where management is not conducive to the retention of the introduced species, reversion can be rapid. Experimentation showed that reversion was more rapid when hay was cut than under grazing alone, grazing in autumn and winter increased the numbers of forbs in the sward, more forbs were present on limed treatments, and hay cutting followed by aftermath grazing produced the greatest species diversity. x Afforestation has probably had the greatest effect on hill-edge habitats over the last 50 years. Few plant species survive under mature conifers, though a more varied ground flora may persist in the rides.
108 x Approximately 4.5% of marginal uplands is covered by bracken. Bracken has increased over the past few decades, and probably continues to do so in spite of efforts to control it. Factors potentially causing the expansion of bracken stands include burning, reduced cutting (for fuel, bedding etc), clear felling of woods, decreased intensity of farming, and the replacement of cattle by sheep. x Grazing is the most important factor in the decline of juniperus. Light grazing in summer is beneficial because it reduces competition from other species, but grazing in winter or at high stocking rates is detrimental to the persistence of juniperus. However, other factors are also important. Regeneration seems to depend on the availability of bare ground or short open swards where seedlings experience little competition. Establishment has often been most successful where grazing pressures have varied over time.
109 INVERTEBRATES
Summary x The published literature on invertebrate species associated with hill-edge habitats was reviewed to identify gaps in knowledge and highlight species and habitats of conservation concern, and their degree of dependency on the hill-edge. x Upland invertebrates are surprisingly diverse, in contrast to upland plants or vertebrates. This diversity may be dependent on the mosaic of habitats characteristic of the hill-edge. Topography and plant structure are also important for invertebrates in the grassland habitats. x Within hill-edge habitats, invertebrates function in the decomposition of plant material, and as food for a number of vertebrate species. x The effects of management practices on invertebrate communities are assessed. In general, those associated with land improvement (drainage, ploughing, reseeding and the use of herbicides and insecticides) are considered to be detrimental. Heavy grazing by sheep can lead to low diversity, as can cutting, burning and afforestation. Practices which maintain the mosaic nature of the hill-edge, and which help retain wet flushes, are generally beneficial to invertebrates. x A number of UK Habitat Biodiversity Action Plans exist for hill-edge habitats including upland heathland, upland calcareous grassland and upland hay meadows. Woodlands (upland mixed ashwoods, upland oakwood, native pine woodlands and wet woodland) may also occur, along with limestone pavements and blanket bog. Each of these habitat BAPs list priority species for which species BAPs have been prepared. Of these priority species, several are likely to be dependent on the hill- edge. x Local BAPs for the Peak District and Dartmoor National Parks were also reviewed, and a number of additional species of conservation importance identified. x Gaps in knowledge are identified. These include identification of communities associated with upland grasslands, heathlands, hay meadows and mixed ashwoods, and more specific studies such as the habitat requirements of butterflies associated with bracken-dominated habitats, mason bees and the parasitic ruby-tailed wasp.
Aim To review invertebrate species associated with hill-edge habitats, identify gaps in knowledge and highlight species and habitats of conservation concern and the degree of dependency of the vulnerable species on hill-edge habitats.
Introduction For the purposes of this review, the hill-edge is taken to include the upper area of agricultural enclosure (mainly pastures and hay meadows), the fence or wall boundary, and the lower reaches of unenclosed habitats (including mainly rough grazing and heathland, but also bog, exposed rock and woodland). Whereas neither the plants nor vertebrates are particularly diverse in upland heathlands, the invertebrates (some groups at least) are surprisingly diverse (Usher & Thompson, 1993). This is likely to be related to the characteristic habitat mosaic or patch structure (Usher & Thompson, 1993) that is critical for conservation. The patch
111 structure is determined by three variables: moisture, vegetation development and soil type.
Until 1985, most of the information on uplands had been derived from one site, the Moor House National Nature Reserve, in the Northern Pennines (Coulson & Butterfield, 1985).
Invertebrates are involved in nutrient cycling, assist in the decomposition of plant material and are important sources of food for a number of vertebrates including lizards and snakes, small mammals and birds (Cadbury, 1999; Coulson 1988).
The habitats and their associated invertebrate fauna The habitats of the hill-edge are broadly delineated by two major soil types: mineral soils below the limit of agricultural enclosure and peat soils above. The invertebrate fauna associated with mineral soils has great affinity with lowland grassland communities and those associated with peat soils show affinities with the sub-arctic communities which have adapted to damp and cold conditions (Dixon, 1984). Coulson & Butterfield (1978) describe the species, biomass and diversity associated with the two different soil types. The numbers of animals are greatest on the mineral soils, least on the peat soils and intermediate on the ‘moor edge’. Different groups of animals predominate on each, e.g. earthworms are abundant on mineral soils and virtually absent on peat soils. In contrast, craneflies Tipulidae and Hemipterans are more numerous on the peat soils.
The hill-edge includes several habitats for which UK Habitat Biodiversity Action Plans (BAPs) exist (Anon.,1995; JNCC, 2001), which gives an indication of their relative importance in conservation terms. ‘Upland heathland’ is defined as lying below the alpine or montane zone and usually above the upper edge of enclosed agricultural land. ‘Upland calcareous grassland’ is also defined as lying above the upper limit of agricultural enclosure, and ‘upland mixed ashwoods’, ‘upland hay meadows’, ‘upland oakwood’, ‘limestone pavements’, ‘native pine woodlands’, ‘wet woodland’ and ‘blanket bog’ may also occur within the hill-edge. A BAP does not exist for upland enclosed pasture, which suggests that it is regarded as being of lesser importance.
From a study of 42 sites on peat or upland grassland in Northern England, Coulson & Butterfield (1985) identified seven different communities of invertebrates associated with the following habitats: lowland oligotrophic mire, high altitude blanket bog, lower altitude blanket bog, ‘mixed’-moor, dry northern heath, ‘edge’-peat and upland grasslands. Further upland grassland communities may be identified in a more extensive survey. They concluded that a mosaic of wet and dry areas, together with mineral soils, possesses a much more diverse invertebrate fauna than more uniform habitats. Differences in the seasonal abundance of invertebrate groups were found between the habitats and may explain differences in abundance of their vertebrate predators. Coulson (1988) describes the invertebrate communities in five of the habitats in this study, and notes that worms (Lumbricidae and Enchytraeidae) formed the majority of the standing crop in four of them, and 24% of the total on the fifth. Appreciable variation between communities was attributed to Diptera (increasing with altitude) and Lepidoptera (decreasing with altitude). Hemiptera, Araneae and
112 Coleoptera contributed little. The communities functions included nutrient cycling, decomposition and as a food resource for vertebrates.
Coulson & Whittaker (1978) and Coulson (1988) recorded an overall greater abundance of arthropods on blanket bog compared with limestone grassland. However, Coulson & Whittaker (1978) recorded a much lower earthworm density in the blanket bog and Thompson (1984) found greater densities of Coleopterans and Lumbricids in improved pasture than blanket bog.
Luff & Rushton (1989), in their study of spiders and carabids of upland pasture, found there was considerable variation between individual unimproved grassland sites but that improved sites had a depleted fauna similar in species composition to intensively managed lowland sites (Rushton, Luff &Eyre, 1989), and characterised by mobile, invasive species. Similar conclusions were reached by McFerran et al. (1994) who studied spider communities in five upland vegetation types in County Antrim, Ireland; grazed plots were dominated by species characteristic of disturbed land. Inbye land and areas where grazing had ceased had coloniser species.
Topography and plant structure of pasture and meadow habitats are important for invertebrates (Andrews & Rebane, 1994a). Although few insects eat bracken, it is an important structural component of upland habitats, providing support for orb-web spiders and cover and shelter for flying invertebrates (Andrews & Rebane, 1994b). Bracken, however, may be the most suitable vegetation for tick survival (ADAS, 1990).
Significant differences in invertebrate abundance were found between five habitats in the North York Moors (bog, damp heath, young heather, building heather and mature heather) (ADAS, 1990). Araneae, Diptera and Hemiptera were most abundant in bogs whereas Opiliones and Carabids were most abundant on drier Calluna heath.
Management practices and their effects on invertebrates Coulson (1988) considers drainage, grazing, burning and afforestation in relation to the invertebrate communities of peatlands and moorlands. He concludes that the effects of these management practices are variable, but tend towards a reduction in biomass and number of species. Morris (1978) selectively reviews grassland management in general (grazing, cutting, burning, treading and trampling, use of fertilizers, ploughing, rotivating and re-seeding) in relation to invertebrates. He concludes the effects increase in severity in this list, with re-seeding having the most detrimental effects on invertebrate faunas.
Livestock grazing Grazing pressure can affect invertebrate communities through changes in vegetation structure (Fuller & Gough, 1999), which can have knock-on effects further up the food chain.
Baines (1996) found that heavily grazed moors supported 41% fewer invertebrates; threefold fewer Lepidoptera larvae and half as many Araneae and Hemiptera. Heavy sheep grazing can create an extremely uniform, short sward and is generally considered to lead to a decrease in invertebrate biodiversity, for example, that noted
113 in the Welsh uplands in an English Nature report on common lands (Aitchison & Medcalf , 1994). However, under these conditions, sub-surface invertebrates may be enhanced by dunging (Fuller & Gough, 1999). Input of readily assimilated nutrients is probably the reason for the increased abundance of soil and turf invertebrates found in heavily grazed areas in Wales (Keiller et al., 1995). However, they also concluded that withdrawal of grazing was likely to lead to an increase in the diversity and abundance of spiders, Diptera and Carabids. The dung itself creates habitats for invertebrates, but some anti-parasitic drugs present in the dung may affect non-target invertebrates. Madsen et al. (1990) found that Diptera, in particular, were adversely affected by Ivermectin for up to 30 days post-treatment, although Wardhaugh et al. (1993) report transient effects on insects feeding on sheep dung. Also, where grazing promotes the build-up of thick mats of vegetation, there may be an increase in the numbers of ticks (Hudson, 1995).
Cherrett (1964) sampled spiders either side of sheep-proof fencing separating grazed and ungrazed limestone grassland in the Moor House NNR. He found greater numbers of species and biomass in the ungrazed sites. Bell et al. (2001) found that with high intensity management, spider communities lack diversity and low intensity management produces more complex communities and more niches.
The cessation of grazing by cattle and the abandonment of traditional bracken management in the uplands have been linked to declines in the high brown and pearl- bordered fritillaries Argynnis adippe and Boloria euphrosyne (Anon., 1995). Stuart (1997) recommends that traditional management of bracken (by light grazing by cattle, pony or horse, manual cutting of seasonal paths and small scalloped areas and no herbicide, flailing, rolling or burning) is beneficial for the high brown fritillary. In his surveys of high brown fritillary and other invertebrates in Dartmoor National Park, Boyce (2000a, b) concluded that the key management requirement for all the species considered is to maintain extensive, mixed grazing of their habitats.
Land improvement (draining, ploughing, re-seeding with competitive grass mixtures and use of pesticides, herbicides and inorganic fertilizers). Within moorland, wet flushes support concentrations of invertebrates (Hudson, 1988; Coulson & Butterfield, 1985), so management which results in a reduction in wet flushes will generally be detrimental. Coulson & Butterfield (1985) argue that the practice of moorland drainage to improve heather or grass growth must be questioned. It is wet areas that produce the spring peak of invertebrates, and habitats with a mosaic of wet and dry areas that harbour greatest invertebrate diversity. Andrews and Rebane (1994b) point out that many upland plants require wet ground conditions and flushes are often rich in plant variety and so are good for insects. Coulson et al. (1990) found than drainage ditches were detrimental to invertebrate species inhabiting wet peat pockets. Hudson (1988) advocates the construction of artificial bog flushes in areas without base-rich rock, to increase the abundance of arthropod chick food for upland birds.
Baines (1988, 1990) found that land improvement resulted in changes in the abundance of several groups of invertebrates. It increased the density and biomass of earthworms and the biomass of beetles other than Carabids. It decreased the number and biomass of spiders, and decreased the biomass of Carabids. Improvement did not
114 change the density or biomass of Tipulid larvae, but decreased the number of species. Luff & Rushton (1988, 1989) also found unimproved pasture to have greater biomass and diversity of spiders and Carabids than improved. They concluded that pasture improvement had a much greater effect on communities than subsequent pesticide use, due to emigration from unsprayed areas. Differences in the ground beetle and spider communities between sites could be explained by the extent of disturbance and subsequent pesticide use (Rushton et al., 1989). Rushton & Luff (1988) demonstrated that Chlopyriphos affects communities of both groups on unimproved pastures.
Cutting and burning Andrews & Rebane (1994a) suggest that hay meadows are less good for invertebrates than pastures because they lack the varied vegetation structure and bare ground.
In a study of five habitats in the North York Moors, it was concluded that heather burning and cutting were likely to assist in maintaining the diversity of the invertebrate community (ADAS, 1990). McFerran et al., (1995), working in County Antrim, also conclude that the maintenance of a mosaic of stands of varying age of Calluna is as essential for the conservation of invertebrate groups as it is for the management of plant species and vertebrates such as red grouse. However, Andrews and Rebane (1994a) and Gimingham (1981, cited in Usher & Gardner, 1988) state that burning can reduce invertebrate diversity.
Bracken control (cutting and/or burning) may damage the egg-laying habitat of the threatened high brown fritillary. Stuart (1997) and Boyce (2000a) recommend cutting and burning should be tightly controlled in known breeding areas.
Afforestation Butterfield et al. (1995) investigated Carabid communities in upland forests and concluded that afforestation with conifers introduces higher invertebrate diversity into upland areas. However, there was a reduction in the rarer Carabid species, especially those associated with wetter sites, so forests should be managed to maintain the wetter areas within them. The rotational forest management cycle, although continually creating open habitat conditions, does not favour rarer species. Clarke & Robertson (1993) showed that woodland management was important for the survival of the pearl-bordered and small pearl-bordered fritillaries.
High profile invertebrates
Lepidoptera Fewer lepidoptera larvae are found on heavily grazed than lightly grazed moorland (Baines, 1996) and pine forest (Fuller & Gough, 1999).
The high brown fritillary Argynnis adippe is Britain’s most threatened butterfly. It has declined in range by over 94% in 30 years (Warren, 1995). The last few colonies are associated mainly with bracken on scrubby grasslands and hillsides (CCW, 1996), usually at low altitudes (Warren, 1995). The decline in the species may be related to the drastic decline of coppicing during the twentieth century combined with the replanting of ancient deciduous woodlands with conifers during the 1950s and 1960s
115 (Warren, 1995), and possibly also to the agricultural improvement of bracken- dominated grasslands, especially those associated with common land (Boyce, 2000). An extensive survey by Stuart (1996) confirmed the dependence of the species on the bracken habitat (it lays it’s eggs on dead bracken close to its larval food-plants, hairy violet Viola hirta and common dog-violet Viola riviniana) and found a 50% increase in known sites. He concluded that the type of bracken habitat required by fritillaries was not common and was best managed by traditional methods (Stuart 1996, 1997). Warren & Oates (1994) discuss bracken control programmes in relation to the conservation of fritillaries, and note that there is potential for conflict along lower moorland edge slopes. They consider that there is an urgent need to protect valuable bracken habitats from control programmes that may be damaging. This is already underway in some regions such as the Dartmoor and Exmoor ESAs. Boyce (2000) surveyed Dartmoor (one of three remaining strongholds) in 2000 and concluded that the butterfly had contracted into a handful of core areas and that there was urgent need to maintain pony and/or cattle grazing and control burning on breeding sites.
The pearl-bordered fritillary breeds in woodland clearings or unimproved grassland habitats with scattered scrub or bracken. Its rapid decline over the last 50 years has been linked to cessation of grazing and abandonment of traditional bracken and coppice management (Anon, 1995). The small pearl-bordered fritillary Boloria selene breeds in similar habitat, particularly favouring damp areas. The dark green fritillary Argynnis aglaja favours exposed grassy slopes on moorlands and in open woods. All three species lay mainly on dog violet Viola canina. The checkered skipper Carterocephalus palaemon, now restricted to western Scotland, occurs in areas of lightly grazed or ungrazed grassland, scrub or marsh, around open broadleaved woodland and its decline has been linked to inappropriate grazing management of woodland pasture and the loss of open areas within woods (JNCC, 2001).
Araneae Upland spider communities are surprisingly diverse; 20% of British spiders occur in the North York Moors National Park (Usher & Thompson, 1993). Unimproved pasture has greater diversity and biomass than improved (Luff & Rushton, 1988,1989; Baines, 1990; Cherrett, 1964). Vegetation structure appears to be important in determining spider communities (Luff & Rushton, 1989; Hudson, 1988; Coulson & Butterfield, 1986; McFerran et al., 1994). Grazing results in dominance by species characteristic of disturbed land (McFerran et al., 1994). Inbye land and areas where grazing has ceased are dominated by coloniser species (McFerran et al., 1994). Diversity declines with altitude (Coulson & Butterfield, 1986).
Cherritt (1964) found the Moor House NNR spider fauna to be dominated by the Family Linyphiidae, the hammock-web building spiders (which he found comprised 73% of all species sampled), and this was significantly greater than the 41% found by Duffey (1962) for a lowland grassland site near Oxford. Aggregations occurred in patchy Calluna/Eriophorum vegetation, and in unevenly grazed alluvial grassland, and high numbers of spiders were found only in the tussocks.
Carabidae Carabid communities are also diverse; 15% of British species are found in the North York Moors National Park (Usher &Thompson, 1993). Ground beetle community
116 structure is more usually related to soil structure and moisture rather than vegetation structure (Luff & Rushton, 1989). Unimproved pasture has greater diversity and biomass of Carabids than improved (Luff &Rushton, 1989; Baines, 1990; Luff & Rushton, 1988). Upland grassland Carabid communities in northern England are distinctive; they show little affinity with those reported from grasslands in continental Europe or lowland Britain (Butterfield & Coulson, 1983). Although few species are restricted to high altitude, there are a number of species that are more frequently encountered at upland sites (Butterfield & Coulson, 1983). It is likely that their habitat requirements depend mainly on physical factors. Usher & Thompson (1993) could also find little evidence for distinct communities of ground beetles on upland heaths, rather a continuous variation with the assemblages of species reflecting the wetness of the site.
Holmes et al. (1993) investigated the ground beetle fauna of Welsh peatlands. They found that Carabid distribution was influenced by (i) acidic vs nutrient-rich conditions, (ii) degree of saturation of the substrate, (iii) altitude and (iv) grazing.
Butterfield et al. (1995) investigated Carabid communities in upland forests and concluded that although forests contained as many species as the surrounding open habitats, many of these only occur on the clear felled areas. There was also a reduction in the rarer Carabid species, especially those associated with wetter sites.
Species and habitats of conservation concern Usher and Thompson (1993) indicate that few of the invertebrates of upland heathland are internationally rare and most of the nationally rare species occur in the montane zone rather than the sub-montane. Similarly, relatively few scarce invertebrates are restricted to moorland. These are listed in Backshall et al. (2001), and include 16 species of moths (including four priority species in the UK Biodiversity Action Plan: Epione paralellaria, Xestia alpicola alpina, Xestia ashworthii and Xylena exsoleta), four species of butterflies (including priority species scotch argus Erebia aethiops and heath fritillary Melitaea athalia), two species of bugs, four species of fly (including Tipula serrulifera, a Red Data Book endangered species (RDB1)), nine beetles, one bee, six spiders and two species of snail (two whorl snails, Vertigo genesii, and Vertigi geyeri, which are priority and RDB1 species and listed under Annex II of the Habitats Directive).
In contrast, meadows and enclosed pastures in the uplands support a rich variety of wild plants and animals, including many rare species of invertebrates (Backshall et al. 2001). These include nationally rare, scarce or uncommon butterflies (the northern brown argus Aricia artaxerxes, the small blue Cupido minimus, high brown fritillary, pearl-bordered fritillary, dark green fritillary and Duke of Burgundy fritillary Hamearis lucina) and the root-feeding click beetles Anostirus castaneus and Selatosomus pectinicornis. Unimproved grassland with a good cover of bracken is the breeding habitat for a number of threatened fritillary butterfly species, often in bracken/grass mosaics that are maintained by stock grazing, usually including cattle or ponies (Warren & Bourn, 1997; Anon., 1995). Important species include the high brown fritillary and pearl-bordered fritillary as well as the declining small pearl- bordered fritillary and dark green fritillary.
117 Those Biodiversity Action Plan priority species believed to be associated with upland oak and ash woodland are listed in Backshall et al. (2001), and include the blue ground beetle Carabus intricatus, found in Britain in only two small woods on the edge of Dartmoor. Backshall et al. (2001) also list those species associated with crags, scree and limestone pavement, which include the narrow-mouthed whorl snail Vertigo angustior, a priority species.
Table 5.1. Habitat Biodiversity Action Plans relevant to the hill-edge, invertebrate priority species listed and their dependency on the hill-edge (Anon, 1995; JNCC, 2001). Habitat Priority species Dependency on hill-edge upland heathland cranefly (Savtshenkia) serrulifera unknown moths Xestia alpicola alpina probably not (more dependent on montane habitat) and Xylena exsoleta. probably not (recorded in a wide range of upland and moorland habitats) blanket bog no priority invertebrates are principally associated with this habitat upland calcareous mason bees Osmia inermis and O. Probably very dependent (Osmia grassland parietina, inermis nests found 300-600m, in calcareous areas in short dry heathery turf which was closely grazed, O. parietina nests found in cavities in dry-stone walls and holes in dead wood) ruby-tailed wasp Chrysura hirsuta probably very dependent (is a parasite of Osmia spp.) snails Vertigo geyeri and V. genesii. probably not (they are alpine species, associated with springs) Limestone none listed pavements upland hay meadows none listed upland mixed netted carpet moth Eustroma probably not (restricted in distribution Ashwoods reticulatum by foodplant to wet woodland, by streams, seepages and lakesides) pearl-bordered fritillary Boloria partially dependent (breeds in euphrosyne woodland clearings or unimproved grassland habitats with scattered scrub or abundant bracken). high brown fritillary Argynnis adippe. partially dependent (found on limestone outcrops and bracken slopes upland oakwood checkered skipper butterfly probably very dependent (associated Carterocephalus palaemon in some with woodland edge and scrub in Scottish sites areas of lightly grazed or ungrazed grassland, dominated by its larval foodplant purple moor-grass Molinia caerulea) wet woodland weevils Melanapion minimum and probably not (associated mainly with Rhynchaenus testaceus, lowland habitats) the craneflies Lipsothrix ecucullata, probably not (associated with wet L. nervosa, L. errans and L. rotten fallen trees in streams) nigristigma the netted carpet moth Eustromia probably not (see above) reticulata
118 Habitat Biodiversity Action Plans have been drawn up for upland heathland, blanket bog, upland calcareous grassland, limestone pavements, upland hay meadows, upland mixed ashwoods, upland oakwood and wet woodland (JNCC, 2001). Table 5.1 gives the priority species listed in each National BAP.
Local BAPs also exist for unimproved pasture, lead rakes, rough grazing, limestone heath, blanket bog, heather moorland, upland ashwood and upland oak/birchwoods in the Peak District. Species listed as being of importance, and which may be dependent on hill-edge habitats, are shown in Table 5.2.
Table 5.2. Species listed in the Peak District local habitat Biodiversity Action Plans, for which hill- edge habitats may be important. Species Habitat northern wood ant upland oak/birchwood habitat shining guest ant Formicoxenus nitidulus upland oak/birchwood habitat ash-grey slug upland oak/birchwood habitat purple hairstreak butterfly Neozephyrus quercus tops of oak and ash, in upland oak/birchwood habitat waved carpet moth Hydrelia sylvata upland ashwood coppice white-spotted pinion moth Cosmia diffinis upland ashwood habitat; foodplant is elm square-spotted clay moth Xestia rhomboidea upland ashwood common fan-foot moth Pechipodo strigilata upland ashwood lemon slug upland ashwood
Table 5.3. Important invertebrate species found to be present in the common lands and wet pastures of Dartmoor National Park (from Boyce, 2000b), for which hill-edge habitats may be important. Species Habitat fairy shrimp Chirocephalus diaphanous (RDP2) temporary pools with bare muddy areas on common land southern damselfly Coenagrion mercuriale acid flushes on common land and wet pastures (UKBAP) small red damselfly Ceriagrion tenellum (DBAP) acid flushes on common land and wet pastures scarce blue-tailed damselfly Ischnura pumilio acid flushes and shallow pools on common land (DBAP) and wet pastures keeled skimmer Orthetrum coerulescens (DBAP) acid flushes on common land and wet pastures high brown fritillary Argynnis adippe (UKBAP) south-facing bracken slopes with abundant dog violet pearl-bordered fritillary Boloria euphrosyne south-facing bracken slopes with abundant dog (UKBAP) violet marsh fritillary Euphydryas aurinia (UKBAP) wet pastures with abundant devil’s bit scabious narrow-bordered bee hawkmoth Hemaris tityus wet pastures with abundant devil’s bit scabious (UKBAP) blue ground beetle Carabus intricatus (UKBAP) oak/beech woodland Kugelann’s ground beetle Pterostichus kugelanni south-facing heathland with abundant bare (UKBAP) ground Paederus caligatus a rove beetle (RDB3) acid flushes on common land hornet robber fly Asilius crabroniformis pony and cattle grazed unimproved grassland (UKBAP) bog hoverfly Eristalis cryptarum (UKBAP) acid flushes on common land and wet pastures Conservation status: UKBAP UK BAP Priority species, DBAP Dartmoor BAP species, RDB2 vulnerable, RDB3 Rare.
119 Boyce (2000b) lists important invertebrate species dependent on the extensive grazing systems of the Dartmoor National Park (Table 5.3). These species may be dependent on hill-edge habitats.
Coulson & Butterfield (1985) list 21 rare species of invertebrates, and describe their abundance and distribution among the seven upland communities identified in their study (which covered peat and upland grassland sites). The 21 rare species were divided into Araneae (5 spp), Staphylinidae (4 spp), Carabidae (1 spp) and Diptera (11 spp). Greater numbers of the rare species were found in the grassland, edge peat and high altitude blanket bog habitats, and the authors identified the grassland habitat in particular (especially those surrounded by blanket bog), as requiring further extensive survey. Coulson (1978) lists 23 rare insects and spiders recorded from Upper Teesdale.
The dependency of the vulnerable species on hill-edge habitats Andrews & Rebane (1994b) point out that many herbivorous insects have specific requirements for particular plants on which they feed. Thus if rare insect species are present in hill-edge habitats it is likely that they are dependent on upland species of plants. For example, of over 50 species of moths which live on hill and upland grazings, over half are dependent on three species of heather.
Priority species listed in upland Habitat BAPs are primarily dependent on upland habitats, many of which are part of the hill-edge habitat mosaic. Table M gives an assessment of the species’ dependency on hill-edge habitats, from information given in the species BAPs.
The high-brown fritillary is dependent on certain bracken communities (but not all, as most are too acidic for their violet host-plants). Suitable communities are those where a variety of herbs are present in the ground flora beneath a moderate to dense bracken canopy (Warren & Oates 1994). Most existing sites that support strong colonies are intensively grazed by cattle, and the butterfly invariably dies out after the cessation of grazing. The pearl-bordered fritillary breeds in unimproved grassland/bracken habitats with scattered scrub or dense bracken and in the early successional stages of lowland woodland. The decline of this species in upland areas has been associated with the cessation of grazing on unimproved grassland and abandonment of traditional bracken and gorse management (Anon, 1995). It must therefore be dependent on these habitats to a large extent.
120 REPTILES AND AMPHIBIANS
Summary
x Little is known about the amphibians and reptiles of upland habitats in Britain. x The species that are most likely to occur on moorland and hill-edge are common lizard, adder, palmate newt, common frog and common toad. x The local abundance of common toad, common frog and palmate newt is probably dependent upon the availability of wetlands and aquatic habitats. x None of the species occur exclusively on hill-edge habitats.
Do hill-edge habitats support species assemblages?
Amphibians and reptiles are found in the uplands, but no species are exclusive to upland areas, indeed most would be typically described as lowland species. Uplands hold large populations of adder, common lizard, common frog, and palmate newt. a). Amphibians
This group of animals can be found in a large variety of habitats, their limiting factor being the close presence of ponds or associated still waters.
Table 6.1. Distributions of amphibians in Britain Species Distribution
Common Frog Occurs in all upland natural areas. Increases thought to have occurred in Rana temporaria Wales and s England. Local declines due to infilling of ponds.
Common toad Widespread in Wales, but does not reach altitudes as high as the common Bufo bufo frog. Occurs in all upland natural areas.
Natterjack toad Very localised populations in Britain. Extinct in Wales in last 30 years due Bufo calamita to destruction of its habitat. Only present in Cumbrian Fell at one site at present, therefore not considered a hill-edge species.
Great crested newt Found throughout Wales, although most common in the east. Occurs in all Triturus cristatus upland natural areas except Exmoor, Dartmoor, Quantocks and Bodmin.
Palmate newt Widespread in mainland Britain. Found from sea level up to 880 m, Triturus helveticus frequently found in hard water areas. Occurs in all upland natural areas
Smooth newt Occurs in all upland natural areas. Less common in Wales, most often found Triturus vulgaris in lowlands of the east. b). Reptiles
Found in large areas of natural and semi-natural vegetation with low levels of disturbance.
Conclusion: All of the common UK herps could be found in hill-edge habitats. Grass snake and great crested newt are more associated with lowland river valleys. Adder, slow-worm, common lizard, smooth newt, palmate newt, common frog and common
121 toad are all hill-edge species (as well as other habitats and altitudes). Vegetation cover and drainage is important to all herpetofaunal species.
Of the rare species, the Natterjack is found largely in sandy, coastal areas, and doesn't have an upland range, but it skirts the large areas of upland in Cumbria and the Solway Firth. The sand lizard and smooth snake are more restricted and have their relative strongholds in Surrey and Dorset, at altitudes of no more than 100m OD (The Herpetological Conservation Trust, pers comm.)
Table 6.2. Distributions of reptiles in Britain. Species Distribution
Adder Most widespread snake in Britain. Occurs in a variety of habitats including Vipera berus moorland, grassland and open woodland, generally below 450m but higher in sheltered places. Occurs in all upland natural areas
Smooth snake Restricted to the heaths of southern England. This species is considered rare Coronella austriaca in Britain.
Grass snake Occurs in most upland natural areas, although sparse cover in N. England. Natrix natrix
Slow-worm Can be found in all upland natural areas. Anguis fragilis
Common lizard Can be found in all upland natural areas. Lacerta vivipara
Are habitat mosaics in the hill-edge ecotone important?
Amphibians and reptiles require extensive areas of appropriate habitat for feeding and hibernating. Herpetofauna can benefit from prolonged availability of invertebrate food at the lower limits of blanket bog formation in NE England. In the altitude zone from 400-500 m, deep peat, heathland and grassland often lie side by side, bringing together several different invertebrate communities. Common frog in particular benefits in this situation. a). Amphibians
The national amphibian survey data (1993) suggests that the upland/lowland interphase is where the best amphibian community ponds are found. These show four or five species sites, where common newt co-exists with palmate newt, for example in Derbyshire and mid-Wales (Mary Swan, De Montfort University, pers comm.)
122 Table 6.3. Habitat preferences of amphibians in Britain Species Habitat
Common Uneven unstructured vegetation e.g. grassland, woodland margins near ponds. Can be frog found in areas with low density ponds (>1 per km2).
Common Requires an uneven structured vegetation e.g. grassland and woodland margins, near or toad connected to ponds or other water bodies with roughly neutral pH. Will travel long distances to breeding ponds. Usually only found in areas with higher densities of ponds (>1 per km2).
Natterjack Have now been found in the uplands. May benefit from localised heavy grazing toad pressure- opens up habitat to provide bare ground and short vegetation for foraging.
Great Fish free pH neutral ponds with contiguous natural habitat. Terrestrial must contain a crested newt diversity of vegetation or physical structure.
Smooth Structurally varied habitats e.g. grassland, woodland edges, quarries, with nearby or newt integral ponds. Usually only in the less acidic ponds.
Palmate More tolerant of upland acidic waters. Can be found in areas with low density ponds newt (>1 per km2).
Amphibians will disperse into a wood that is humid, and with a good ground cover. Terrestrial habitats need to offer structural variation, to provide the invertebrates with food, cover from extremes of temperature and to provide hibernation sites e.g. hedgerows, margins of deciduous woodland, dry stone walls and rocky ground.
All amphibian species spend a large part of the year foraging on dry land and need adequate shelter for hibernation during the winter. Intensification of agriculture, use of chemicals and removal of hedges have had a harmful effect on this species b). Reptiles
Reptiles favour warm, southerly aspects with a diverse vegetation structure, with low levels of disturbance. They require open areas for basking and thermoregulation, with adjacent vegetation to provide cover from overheating e.g. purple moor-grass tussocks and dense bushes of Calluna. A varies vegetation mosaic provides habitats for prey species (invertebrates, small mammals, amphibians and other reptiles). Scrub/grassland edges are important for basking snakes and lizards.
A wide range of topographical features can offer ideal habitats for reptiles. They can be found in new plantation areas for the first five years where there is a good flush of vegetation and a large number of associated small mammal prey species. After 5 years, the afforested areas become unsuitable for reptiles, as the canopy shades out ground vegetation. This will then no longer sustain a population, and will become a barrier to dispersion.
Upland habitats, notably moorland, scrub and newly planted woodland, are valuable habitats for adder, which are becoming scarcer in lowland habitats due to disturbance and habitat loss.
123 Table 6.4. Habitat preferences of reptiles in Britain. Species Habitat
Adder Structurally varied habitats such as moors, woodland edges, ungrazed (or low-intensity grazed) grassland. Especially in areas with several habitat types in close proximity. Bracken thickets, gorse bushes and stunted hedges are favourite hunting grounds. The largest colonies tend to be in areas of extensive heath and moorland, often in association with modern forestry plantations
Grass snake Structurally varied habitats. Often associated with water. More associated with farmland than other species
Common Structurally varied, open habitats, often providing basking areas e.g. banks, woodland lizard margins, open moorland, tussock grassland and bogs. Common in moorland, open woodland and grassland
Slow-worm Structurally varied, open habitats, often providing basking areas e.g. banks, woodland margins, open moorland, tussock grassland and bogs. Common in moorland, open woodland and grassland
Conclusion: The hill-edge ecotone provides the unstructured, varied habitat needed by herpetofauna for food, shelter and hibernation. Although this is not the only habitat to provide this diversity, the lowland heaths and grasslands that more commonly support these species are increasingly under threat from development and disturbance. Therefore, hill-edge is becoming an increasing stronghold for these otherwise fragile animal groups.
Are hill-edge habitats important for moorland species?
Upland areas have few species of amphibians and reptiles, although common frog and viviparous lizard are widespread on heather moorlands. Upland sites have been lost to afforestation. Moorland produces some of the most extensive habitats remaining. Sand lizard and smooth snakes are confines to the southern heaths, but Natterjack toad is present in one site in the Cumbrian Fells.
Moorlands can provide valuable habitats for Herpetofauna. Frogs, toad and newts may be restricted in the use of these areas by the occurrence of suitable breeding ponds.
Dartmoor heather moorland contains good populations of adders and lizards. Records have shown that the North York Moors and the Yorkshire Dales also contain common frog, common toad, great crested newt, palmate newt, smooth newt and slow-worm.
Upland enclosed grassland may be of great importance for herpetofauna and it supports several species, including common lizard, common frog and common toad. It will also help to provide connections between other habitats, such as fragmented woodlands/moorland areas. Field margins e.g. dry stone walls and boundary banks often provide habitats of value to reptiles and amphibians.
124 a). Amphibians
There is a reduction in breeding performance at higher altitudes. Uplands are an important reservoir of natural habitat. Later spawning, slower development rate and young frogs and newts leave ponds later, so there is less time to feed before winter. Despite lower reproductive potential, high egg mortality and delay in emergence of juveniles, upland frogs are more numerous than lowland frogs, so there must be a higher survival rate at the later stages in the life cycle (ponds dry out less, and less predators).
Table 6.5. Ranges and habitat use of amphibians in the uplands. Species Habitat
Common Frogs migrate from peat areas to grassland areas to utilise summer emergence of insects frog there. Frogs have a high acid tolerance to survive in the low pH pools.
Palmate Widespread in upland soft water areas. Common in SW England. Upland habitats newt favoured more than lowlands where smooth newt in common. Pools with pH as low as 3.9 are used. Particularly associated with heathland and moorland sites of low fertility and low pH.
Smooth Less common in upland areas. Rarely found in ponds where the pH is less than 6.0. newt
Great This species has been found in the following upland natural moorland areas: - crested newt Yorkshire Dales, Cumbrian Fells and Dales, S. Pennines, Pennine/Dale fringe, N. York moors and Hills, Dark Peak, SW Peak, White Peak (a nationally important stronghold for the species), Derbyshire Peak, Oswestry Uplands, Somerset levels and Moors. b). Reptiles
Table 6.6. Ranges and habitat use of reptiles in the uplands. Species Habitat
Common Widespread up to 766m altitude, preferring driers moors. Common in Dartmoor, lizard Bodmin and Exmoor. The structural diversity of the hill-edge habitat, and hedges and walls of the hill farms would aid the dispersal of this species.
Slow-worm Lower altitude moors and common in SW England. This species favours a less extreme environment.
Adder The only snake to be found in the upland areas. Grasslands, heath, moor and blanket bog up to 600m. Habitat use varies seasonally. Disturbance, and heath and moor fires affect distribution locally.
Conclusion- Moorland provides some of the most extensive areas of natural and semi- natural vegetation left in Britain. The species' most likely to use both hill-edge and moorland are common lizard, adder, palmate newt, common frog and common toad. Local abundance of common toad, common frog and palmate newt will occur within suitable wetland areas. Not one of these species is exclusive to the moorland habitat.
125 Information sources
Backshall, J. et al., (eds.). (2001). Coulson, J.C. & Butterfield, J.E.L. (1978 ). Coulson, J.C. & Butterfield, J.E.L. (1985). Coulson, J.C. et al. (1992). Dartmoor National Park Authority. (1999). Mitchell-Jones, A.J. & Gent, A.H. (1997). Mortimer, S.R. et al., (2000). Swan, M.J.S. & Oldham, R.S. (1993a). Swan, M.J.S. & Oldham, R.S. (1993b).
Websites: www.reptiletrust.com/reptile_care/care_sheets/bristish_reptiles/common_adder.htm www.dartmoor-npa.gov.uk/dnp/pubs/natureodp2.pdf www.wildlifetrust.org.uk/sheffield/BAPS/writtenplans/newts.html www.devon-cc.gov.uk/biodiversity/heath.html
126 BIRDS
Summary x The review assessed the value of hill-edge habitats to birds in upland England and Wales, examined population changes of characteristic hill-edge species, and considered the factors responsible for those changes. The conservation importance of hill-edge bird populations was evaluated by reference to national and international criteria. x Distinctive assemblages of breeding species were identified from hill-edge habitats in the Pennines, the ffridd in Wales and Dartmoor. x The composition of the species assemblages breeding in hill-edge habitats varied between regions. Waders were the dominant group in the northern Pennines but comprised a relatively minor component of species assemblages on the hill-edge in Wales and SW England. Passerines of scrub and woodland margins were the characteristic species on the ffridd and on Dartmoor. x Different species exploited hill-edge habitats in different ways. Two species were largely restricted to the hill-edge: black grouse and red kite (Welsh population only). Six moorland species – golden plover, curlew, ring ouzel, twite, merlin, golden eagle - and possibly hen harrier exhibited some dependence on hill-edge habitats. x Numbers of most hill-edge species have declined in most regions of England and Wales. Only red kite and twite showed significant increases. x The causes of the declines have not been identified in most cases. This is because population processes are poorly understood for most species, except for the red kite, and because data on habitat usage by the species in decline and the consequences of land use change are often lacking. x Spatial comparisons of habitat use by waders and black grouse respectively generated predictions about the relationship between population trends, agricultural improvement and/or changes in grazing pressure on the hill-edge. The prediction that wader populations should decline when hill-edge habitats are improved agriculturally was supported by some comparisons between time-series of counts and concomitant habitat changes but not others. In contrast, the prediction that black grouse densities and breeding success should increase following a relaxation of grazing was supported by a replicated field experiment. x Afforestation with non-native conifers has effected extensive and long-lasting habitat changes on the hill-edge. Most bird species of open country desert plantations at an early stage. Black grouse, short-eared owl, hen harrier and whinchat exploit young plantations but desert them when the woodland canopy closes. x The effects of afforestation may extend beyond the boundaries of the planted areas by reducing the food supply of birds of prey and carrion eaters that hunt for food on the hill-edge, thereby resulting in population declines. x The hill-edge supports 13 species that are covered by the EU Birds Directive (Annex I) and/or are included in the Red and Amber Lists of Species of Conservation Concern. Two of the species – red kite and black grouse- are hill-edge specialists, while a further seven are moorland species that exhibit a degree of dependence on hill-edge habitats. The capacity of the hill-edge to
127 support these species over the long-term is of national and, in some cases, international concern.
Introduction
This review comprises three parts. The first addresses four questions about the value of hill-edge habitats to birds in upland England and Wales:
1. Do hill-edge habitats support distinctive assemblages of breeding birds? 2. Are habitat mosaics in the hill-edge ecotone important for breeding birds? 3. Are hill-edge habitats important for species nesting on adjacent moorland? 4. Are hill-edge habitats important for particular bird species outside the breeding season?
The second part of the review examines population changes of birds using habitats on the hill-edge, and considers the factors that were responsible for those changes.
The third part considers whether the hill-edge in England and Wales is nationally important for the conservation of upland birds.
This review draws principally on datasets collected in England and Wales but examples from Scotland have been used to illustrate or amplify particular points.
The value of hill-edge habitats to birds in the uplands of England and Wales
(i) Do hill-edge habitats support distinctive assemblages of breeding birds?
Species-assemblage level studies
Ratcliffe (1977a, 1990), Fuller (1982) and Thompson et al. (1995) give outline descriptions of the distributions and habitat associations of the breeding birds of moorland and the hill-edge in Britain. However, regional and local surveys of upland birds, especially waders, provide the main source of quantitative information on the breeding bird communities of hill-edge habitats in England and Wales (Table 7.1). These surveys often had different objectives and used different data collection methods. Nonetheless, they provide a composite picture of the breeding bird communities of hill-edge in many, though not all, regions of upland England and Wales (Table 7.1). Though most of these surveys cover hill-edge and adjacent moorland and/or improved grassland, in only a small proportion of cases were separate datasets from the hill-edge, improved farmland and moorland respectively presented to permit comparisons between habitats. This subset of surveys comprises the main source material for the assessment. They include studies from the North Pennines, South Pennines, central Wales and SW England (Dartmoor).
128 Table 7.1. Sources of data on breeding bird species or communities in the uplands of England and Wales that refer to hill-edge habitats, indicating range of habitats covered. Hill-edge (2) denotes whether counts or densities of breeding birds that are specific to hill-edge habitats are given. District Year(s) Source Species Moor Hill- Impro Hill- edge ved edge (2) farmla nd Lake District 1993 Murray et al. (1995) Waders -++ -
Northern Pennines New Hall Farm, Eden 1962-71 Robson & Williamson All -++ + Valley, Cumbria (1972) Upper Teesdale/Eden 1985-87 Baines (1988b) Waders -++ + Valley Baldersdale/Lunedale 1993 Shepherd (1993) Waders -++ - “ / “ 1999 Small et al. (1999) Waders -++ - Yorkshire Dales 1988 Curtis et al. (1991) All +++ + Pennine Dales ESA 1991-95 ADAS (1996) Waders & -++ + yellow wagtail Yorkshire Dales 2000 Shepherd (2001). Waders -++ -
Forest of Bowland 1993 Campbell et al. (1993) Waders -+? - “ “ “ 1998 Babbs (1999) Waders -+? -
North York Moors 1992 Allinson (2001) Selected(1) ++- - “ “ “ 1996- Wightman (2001) Waders +++ - 2000
Southern Pennines Forest of Trawden 1982-83 Haworth & Thompson Selected(2) ++? + (1990) South Pennines 1990 Stillman & Brown Selected(3) ++- + (1994) North Peak ESA 1994-96 ADAS (1997) Selected(4) ++- - North Staffs Moors 1985 Waterhouse (1985) All ++? - “ “ “ 1992 Brindley et al. (1992). Selected(5) ++? - “ “ “ 1996 McKnight et al. Selected(6) ++? - (1996).
Wales Mynydd Hiraethog, 1984-5 Bain (1987) Waders -++ + Clwyd Mynydd Hiraethog & 1994 Thomas & Young Selected(7) ++? - Llandegla Moor (1994) North Wales ffridd 1992 Bates (1992) Selected(8) -+- + Central Wales ffridd 1975-77 Lovegrove & All -++ + Bowman (undated) “ “ “ 1985 Hobson (1985) All -+- + “ “ “ 1986-7 Garnett (1988) Selected(9) -+- + Brecon Beacons, Powys 1970-77 Massey (1978) All ++- +
South-west England Dartmoor 2000 Geary (2000) All +++ + Notes: Selected species lists: (1) red grouse, golden plover, lapwing, curlew, redshank, whinchat, wheatear, ring ouzel; (2) golden plover, dunlin, redshank, curlew, merlin, ring ouzel, twite, short-eared owl; (3) merlin, peregrine, red grouse, golden plover, lapwing, dunlin, redshank, curlew, snipe, short-eared owl, whinchat, wheatear, ring ousel, twite; (4) red grouse, golden plover, lapwing, dunlin, snipe, curlew, common sandpiper, skylark, tree pipit, meadow pipit, grey wagtail, dipper, wren, whinchat, stonechat, wheatear, ring ouzel, twite, reed bunting; (5) curlew, snipe, lapwing, redshank, golden plover, black grouse, red grouse, merlin, short-eared owl, cuckoo, ring ouzel, twite, wheatear, whinchat, reed bunting; (6) as for 5 + grey partridge; (7) all waders and diurnal raptors, red grouse, black grouse, grasshopper warbler, ring ousel, stonechat, reed bunting, yellowhammer; (8) skylark, meadow pipit, wheatear, whinchat, redstart, robin, wren, dunnock, willow warbler, chaffinch, yellowhammer; (9) see Table 7.4
North Pennines
The principal source of information on the structure of breeding bird communities in hill-edge habitats in the northern Pennines, and in England as a whole, is the Low Intensity Agricultural Land (LIAL) study (Curtis et al., 1991; Wilson et al., 1991).
129 The LIAL survey methods were applied to a stratified sample of 76 1km squares from the Yorkshire Dales region of the northern Pennines (Curtis et al., 1991). Bird numbers and habitat details were recorded within each 1km square. Habitat data were recorded at a fine spatial scale (20m u 20 m) and were grouped into habitat patches using TWINSPAN (Hill, 1979). A second TWINSPAN analysis was then used to classify the 1km squares from the composition of their habitat patches. Seven habitat groups were generated from the second TWINSPAN analysis. They encompassed a range of habitat combinations from wet-bogs and moorland (Group A), at one extreme, to dry and moist arable land at the other (Group G). Three intermediate groups – moist-rough and neutral grassland (B), grassland with improved pasture (C) and grassland with improved pasture and much bracken (D) - were recognisable as hill-edge habitats. A third TWINSPAN analysis was used to classify the 1km squares from the relative abundance of the bird species that each square contained. Eight bird species assemblages were distinguished (Table 7.2). Not all the bird species used in the classification were breeders. Fieldfares Turdus pilaris were probably late winter visitors whereas rook Corvus frugilegus, jackdaw C. monedula, starling Sturnus vulgaris and woodpigeon Columba palumbus may have been breeding elsewhere but had moved onto moorland and adjacent agricultural habitats to feed during the summer. (c.f. Kahrom & Edington, 1983; Bell et al., 1990).
Each bird species assemblage occurred in several habitat groups (Table 7.3) but the frequency of occurrence of each bird assemblage differed between the habitat groups (Curtis et al., 1991). The hill-edge habitat groups (B, C & D) supported the greatest diversity of species assemblages and the highest number of species overall (Table 7.3). The distinctiveness of the species assemblages occurring in the hill-edge 1km squares was more marked when lists of the scarcer and less widespread species were compared between habitat groups. Habitat groups B, C and D supported 25 species that did not occur in any other group. The list included four moorland species - ring ouzel Turdus torquatus, twite Acanthis flavirostris, raven Corvus corax and short- eared owl Asio flammeus – and five from waterside aquatic habitats - common sandpiper Actitis hypoleucos, dipper Cinclus cinclus, goosander Mergus merganser, wigeon Anas penelope and teal A. crecca.
Table 7.2. Bird species assemblages identified from LIAL study of the Yorkshire Dales (from Curtis et al. 1991) Bird species assemblages (TWINSPAN endgroups) Principal species I II III IV V VI VII VIII Linnet + Golden Plover + Curlew + + Meadow Pipit + + + + + + + Lapwing ++++ + Skylark +++ Starling + + + Black-headed Gull + Snipe + Mallard + Jackdaw + + Fieldfare + Rook ++++ Woodpigeon + Chaffinch + Notes:
130 Table 7.3. Pattern of occurrence of bird species assemblage, and species richness, by habitat group in the Yorkshire Dales (after Curtis et al., 1991). Habitat groups (2) Bird species A BCDEFG assemblage (1) I+++ II + +++ III + ++++ IV ++ V++++++ VI ++++ VII ++ ++ VIII ++ ++
Number of species 35 61 66 50 42 39 14
Notes: (1) - see Table 7.2 for details; (2) - Hill-edge habitat groups shown in bold.
South Pennines
Two datasets describing the distributions and habitat relationships of selected moorland bird species are available from the southern Pennines. Haworth & Thompson (1990) mapped the distributions of eight moorland species, at the 0.5 km square scale, over 150 km2 of the southern Pennines (The Forest of Trawden) in 1982- 83. Matching topographical and vegetation data were also collected. This study not only covered unenclosed moorland but also included enclosed grasslands below the moorland boundary and is the principal source of information on the breeding bird communities of hill-edge in the south Pennines. Using discriminant analysis to model bird-habitat relationships, Haworth & Thompson showed that three species, twite, ring ouzel and merlin Falco columbarius tended to occur along the margins of moorland although none of these species were confined to hill-edge habitats. Twite, ring ouzel and merlin all showed strong associations with Calluna and bracken. This habitat mosaic occurred most frequently on relatively steep ground, as in valleys and marginal slopes of moorland areas. Ring ouzel also showed an association with hill- edge grasslands (see below). Haworth & Fielding (1988) suggested that merlins breeding in the south Pennines preferred mosaics of heather moor and bracken because of the high availability of passerine prey in the ranker vegetation and because there was good cover for nest concealment.
A second survey was carried out over a much larger area (725 km2) of the south Pennines in 1990 (Stillman & Brown, 1994) and, included a repeat survey of the study area used by Haworth & Thompson in 1982-83. Unlike the earlier study, enclosed grasslands adjacent to the moorland boundary were not covered. Nonetheless, the 1990 survey did indicate that some species tended to nest on the moorland margins and it identified habitat associations that are relevant to the hill-edge.
The abundances of 14 species (Table 7.1) and matching topographical and vegetation data were recorded at the 1km square scale. Densities of six species, curlew Numenius arquata, lapwing Vanellus vanellus, snipe Gallinago gallinago, twite, wheatear Oenanthe oenanthe and whinchat Saxicola rubetra, on moorland were negatively correlated with the distance from the moorland edge. However, these correlations did not differentiate between effects of distance from the moorland edge (e.g. energetic costs of commuting between nest on moorland and feeding sites beyond moorland boundary) and the effects of habitat gradients across the moorland margins (e.g.
131 spatial variation in habitat between moorland centre and edge that influenced selection of nest and feeding sites on moorland). The relationship between the birds’ distributions and vegetation was explored further using a constrained ordination technique (redundancy analysis). This analysis identified three principal habitat gradients: a transition from high-altitude areas with high bog cover away from moorland edge to low-altitude areas with high cover of wet flush and grass moor (Axis 1), a transition from steeply sloping areas with high grass and heather cover to flatter areas with high cover of bog (Axis 2), and a gradient from high heather moor, wet flush and tall heather cover to steeply sloping areas with high grass moor and bog cover (Axis 3). The low altitude extreme of Axis 1 corresponded with the moorland margins, where the species scores for curlew, snipe, merlin, twite and whinchat were all concentrated. The scores for the same list of species were tightly clustered in the centre of Axis 2 but the separation of the species’ scores along Axis 3 indicated that there were differences in the species’ preferences for moorland margin habitat: snipe, curlew and merlin tended to occur in areas containing heather moor and wet flush, whereas twite tended to be associated with steep hillsides and grass moor.
These findings differ from those of the earlier survey in several respects. This may have been because different analytical methods were used and/or because the second study covered a much larger area with a greater range of habitats and elevations. It is not possible to evaluate to what degree the relative importance the habitat variables was determined by the analytical method used. However, there is some evidence that differences in the characteristics of the study areas may have accounted for some of the differences in the birds’ use of habitats (see discussion on curlew below). The most obvious difference between studies concerns the importance of bracken cover. Twite, ring ouzel and merlin that had been identified by Haworth & Thompson as hill- edge species showed a strong affinity with bracken. However, these relationships were not identified in the main output from the redundancy analysis of the 1990 survey data. Bracken cover only had a strong effect along Axis 4, which accounted for only a small proportion of the bird-habitat relationship and was discarded in the analyses (Stillman & Brown, 1994).
Two species, ring ouzel and curlew, showed different habitat associations in the two surveys of the south Pennines. Though ring ouzel was clearly identified as having strong affinities with the hill-edge in the 1982-3 survey, this was not apparent from the 1990 survey. The differences were more marked in the case of the curlew, which was identified as a high plateau species by Haworth & Thompson (1990), yet it showed clear associations with moorland margins in the 1990 survey. Similar contrasts in habitat preferences by curlew are evident from other moorland study areas in the eastern Highlands of Scotland (Brown & Stillman, 1993) and the North York Moors (Wightman, 2001). The differences in the patterns of occurrence may be related to the maximum altitude (and associated effects on vegetation) at each site. Curlew tended to occur in the highest parts of moors in the low altitude sites (Haworth & Thompson, 1990; Wightman, 2001), whereas they preferred moorland margins in the high altitude sites (Stillman & Brown, 1994; Brown & Stillman, 1993).
132 Table 7.4. Species composition of breeding bird communities on ffridd land in Wales. The proportion of sites in each sample that was occupied by each species is indicated by constancy values (see footnote). Species 1975-78 1985 1986 1987 (n=13) (n=39) (n=40) (n=40) Source: Lovegrove & Source: Hobson Source: Garnett Source: Garnett Bowman (undated) (1985) (1988) (1988) Meadow Pipit IV V V V Tree Pipit IV V IV IV Yellowhammer IV IV III III Chaffinch IV IV III IV Whinchat III IV IV III Carrion Crow IV IV ?? Redstart IV III II II Wheatear II III IV V Willow Warbler III IV III II Cuckoo IV II ? ? Buzzard IV II ? ? Skylark I III II III Magpie II III ? ? Raven III I ? ? Great Tit II II - I Pied Wagtail I II II III Linnet I III II II WrenIIIIII Dunnock II I I I Mistle Thrush II I I I BlackbirdIIIII RobinIIII WhitethroatIIII Pied FlycatcherII-I Grey WagtailI-II Reed BuntingII-I Stonechat-III Ring Ouzel-III Blue Tit-III Song Thrush -III Garden Warbler-III Redpoll I-II Marsh TitI--I Starling--II Jay-I-- Rook-I-- Spotted Flycatcher--I- Sedge Warbler--I- Siskin --I - Goldcrest---I Coal Tit---I Nuthatch---I Stock Dove I - ? ? Merlin I - ? ? Kestrel I - ? ? Sparrowhawk I - ? ? Snipe I - ? ? Constancy values: - absent; I = 1-20% of sites; II = 21-40% of sites; III = 41-60% of sites; IV =61-80% of sites; V = 81-100% of sites. ? – no data. Species with constancy values of IV or V are shown in bold.
Wales
The principal source of information on breeding birds in hill-edge habitats in Wales is a series of surveys of ffridd habitats in central Wales that was undertaken by the RSPB between 1975 and 1978 (Lovegrove & Bowman, undated), in 1985 (Hobson, 1985) and in 1986 and 1987 (Garnett, 1988). Unlike the LIAL analysis, which
133 identified hill-edge habitat mosaics statistically, the sampling sites used in the RSPB ffridd study between 1985 and 1987 were targeted at hill-edge habitats, using predetermined habitat criteria (Garnett, 1988). Sites were selected to contain different mixes of five habitat types: Calluna/Vaccinium dwarf-shrub heath, gorse (Ulex europea, U. galli), semi-natural grassland, dominated by Agrostis-Festuca, and improved grassland. Sites were chosen to include a representative sample of scrub and woodland ranging from dispersed scrub to patches of relatively dense scrub woodland. Blanket-bog, Mollinia dominated ground and rush (Juncus) pastures were deliberately excluded.
Forty-seven species of bird were recorded from the three RSPB studies (Table 7.4). Only two species, meadow and tree pipit (Anthus pratensis & A. trivialis), were consistently recorded from 60% or more of sites from each sample (constancy values IV and V). A further nine species were recorded from more than 60% of sites in some, but not all, samples: yellowhammer Emberiza citrinella, chaffinch Fringuila coelebs, carrion crow Corvus corone, redstart Phoenicurus phoenicurus, whinchat, wheatear, willow warbler Phylloscopus trochilus, cuckoo Cuculus canorus and buzzard Buteo buteo. The remaining species, mostly from woodland, were much less widespread (Table 7.4). The most widespread species tended to be the most abundant (Hobson, 1985).
The pilot study undertaken by Lovegrove and Bowman included two sites that contained improved grassland. These tended to support fewer species than the unimproved sites and four of the characteristic ffridd species - tree pipit, whinchat, yellowhammer and redstart – were absent. The follow-up study (Garnett, 1988) described the variation in songbird species assemblage along major habitat gradients within the ffridd (see next section) but it did not compare the species assemblage on the ffridd with those of adjacent habitats. However, Massey (1978) did compare breeding bird assemblages in the ffridd with those on unenclosed moorland in Craig Cerrig-gleisiad National Nature Reserve, in the Brecon Beacons. The valley sides in the study area comprised a mosaic of heather, bilberry, bracken, patches of grassland, and hawthorn scrub. These habitats supported eight moorland/grassland species (meadow pipit, cuckoo, wren, wheatear, stonechat, whinchat and pied wagtail) whereas only three bred on the moorland above (red grouse, skylark and meadow pipit). The range of species on the valley sides is similar to that reported from the RSPB study (Table 7.4). Small blocks of larch (Larix) and patches of native deciduous woodland at the base of cliffs supported additional species. Overall, the study by Massey and those by the RSPB suggest that the breeding communities on unimproved ffridd are much more diverse than those on the moorland above and on improved pasture in the valleys.
The distribution maps from the 1988-1991 BTO atlas survey of breeding birds (Gibbons et al., 1993) show that all of the species recorded from the ffridd were widespread in central Wales though it is possible that the combinations of species found in the ffridd were peculiar to that habitat. The occurrence of the whinchat is of particular interest because its range contracted markedly in lowland Britain between 1968-1972 and 1988-1991 and the map of whinchat density from the 1988-1991 BTO atlas survey of breeding birds (Callion, 1994) indicates that the species now has one of its strong holds in the uplands of central Wales. Hill-edge habitats in this region may, therefore, be nationally important for whinchats but further mapping of the
134 species’ distribution, at an appropriate scale, and an assessment of the demographic status (source or sink) of hill-edge populations, are required to confirm this.
The absence of breeding waders from the ffridd is very noticeable. This may be due partly to sampling bias in the RSPB surveys because they deliberately excluded rush pastures, where waders might be expected to occur. However, the birds’ absence may also be genuine and the result of widespread population declines of breeding waders that have occurred in the interior of Wales (e.g. Tyler, 1992; Green et al, 1994; Shrubb et al, 1997).
Table 7.5. Species assemblages of breeding birds in different habitats in Dartmoor in 2000. Mean densities (birds km-2)(+ standard error) of breeding birds in 1km sampled using Breeding Bird Survey methods (Data from Geary, 2000). Moorland Hill-edge Bird species Blanket Mire Heather moor Fragmented Bracken (25 km squares) (25 km squares) heath (9 km squares) (39 km squares) Red Grouse + + Curlew + Dartford Warbler + Skylark 94.4+9.1 56.6+10.3 52.1+6.6 40.8+16.2 Meadow Pipit 81.6+11.5 123.7+26.2 96.6+14.5 53.6+36.5 Whinchat + 4.6+3.2 1.3+0.8 + Yellowhammer + 2.3+1.6 + 16.7+8.2 Stonechat + 12.5+9.3 3.6+1.4 11.8+4.3 Wheatear + 4.1+2.3 18.4+4.8 15.7+8.8 Linnet + 7.9+5.9 7.1+3.4 11.3+9.7 Reed Bunting + + 1.9+1.0 + Snipe + + + + Cuckoo + + + + Grasshopper Warbler + + + + Dunnock 1.5+1.1 8.0+5.1 Robin 0.9+0.7 8.4+4.8 Blackbird 5.6+4.0 8.6+7.3 Wren 2.3+1.3 4.9+1.6 12.1+7.5 Chaffinch 2.0+0.9 4.4+2.4 12.6+9.0 Redstart + + 2.9+1.9 Tree Pipit + + 4.8+3.7 Carrion Crow 3.5+1.3 6.6+3.8 Willow Warbler 0.8+0.5 12.4+7.1 Magpie 0.7+0.5 Lapwing + Notes: + present but in only a small proportion of the 1km squares in each habitat category.
South-west England
Dartmoor comprises the largest area of upland habitat in SW England. The breeding birds of moorland and the hill-edge habitats on Dartmoor were surveyed in the year 2000 (Geary, 2000). Bird densities were estimated from surveys carried out in 1km squares, each of which was assigned to one of four habitat categories: blanket mire, heather moor, fragmented heath and bracken (Table 7.5). For the purposes of this review, the blanket mire and heather moorland were treated as moorland, whereas fragmented heath and bracken were reclassified as hill-edge.
Only four species – carrion crow, willow warbler, magpie Pica pica and lapwing - were recorded exclusively from hill-edge habitats on Dartmoor but eight others - yellowhammer, wheatear, dunnock Prunella modularis, robin Erithacus rubecula, wren Troglodytes troglodytes, chaffinch, redstart and tree pipit - occurred at higher
135 densities on the hill-edge than on open moorland. The species assemblage on the hill- edge in Dartmoor was similar to that recorded from the ffridd lands in central Wales. Many of the characteristic ffridd species – tree pipit, yellowhammer, chaffinch, redstart, wheatear and willow warbler - were either restricted to hill-edge habitats on Dartmoor or occurred at higher densities on the hill-edge than on moorland. However, whinchats were not concentrated on hill-edge habitats in Dartmoor and they occurred in 1km squares from the four habitat categories. Though the constancy value of the bracken squares (IV – 66% occupied) was higher than those of the other habitats (c.f. Wales – Table 7.4), densities of whinchats were highest on heather moor (Table 7.5).
Studies of individual species or families
Birds of prey
The red kite Milvus milvus was omitted from the RSPB ffridd study but it is, nonetheless, one of the most characteristic birds of the hill-edge in central Wales. Birds from the relict breeding population in central Wales nest primarily in woods on valley sides, particularly remnants of oak woodland, and are believed to obtain a significant proportion of their prey from ffridd land (Walters Davies & Davis, 1973; Newton et al., 1981). The availability of unimproved and improved habitats in close proximity may be important to kites when they are hunting for prey. During the study by Newton et al. (1981), sheep carrion was a major food source early in the breeding season and most sheep carrion was available on agriculturally poor (unimproved) land. With the decline in the availability of sheep carrion each breeding season, the birds switched to wild prey - invertebrates, small mammals and birds - that were more abundant on good (improved) agricultural land. Improved pastures tended to contain more invertebrate prey, moles and other prey than unimproved sheep walk and were often favoured places for kites to forage.
Game birds
The black grouse is probably the most characteristic bird of the hill-edge in Britain, yet in the series of community level surveys reviewed above, the species was only recorded from the LIAL study of the Yorkshire Dales (Curtis et al., 1991). This species was probably under-represented in the community level surveys partly because it is very scarce and partly because it requires specific census methods (e.g. Cayford & Walker, 1991).
Black grouse Tetrao tetrix were formerly widespread in England and Wales but their breeding range underwent a major contraction in the 20th century (Cayford, 1990; Hudson & Baines, 1993; Baines & Hudson, 1995). In England and Wales, black grouse are now restricted to the uplands of central Wales (Williams, 1996) and to the Pennines (Yalden, 1986; Hancock et al., 1999) where they tend to occur on the hill- edge. Nonetheless, there are regional differences in the detail of the habitat associations. Until the 1990s, black grouse bred in the Lake Distict where they tended to occur on woodland fringes – scattered larch (Larix spp.) on limestone plateaux and birch (Betula spp.) and rowans (Sorbus spp.) on moorland (Barnes, 1970). In contrast, the breeding population in Upper Teesdale occupies a largely treeless landscape. Here the birds tend to occur in areas where dwarf shrub heath, bog and grass moor lie
136 adjacent to rough grazing and inbye fields (Baines, 1994). In the Peak District, which is more wooded than Upper Teesdale, the remnant breeding population of black grouse is largely restricted to mosaics of woodland, heath and pasture along the hill- edge (Lovenbury et al., 1978; Yalden, 1986). Black grouse breeding in Wales also tend to occur on moorland close to woodland. Most display sites (73%) recorded in a survey undertaken in 1986 were situated either within or on moorland close to conifer plantations. A proportion of sites (30%) were located close to enclosed farmland (Grove et al., 1986). The association between black grouse and hill-edge habitats (moorland, deciduous and coniferous woodland, and pasture) has also been recorded from the Eastern Highlands of Scotland (Parr & Watson, 1988).
The grey partridge Perdix perdix is generally regarded as a lowland species in England and Wales but it is relatively numerous on rough grazing and moorland edges on farms in the Northern Pennines. Mean densities of grey partridges on 27 landholdings in Teesdale, Weardale, Tynedale, North Yorkshire and the Eden Valley between 1989 and 1997 varied from 2 to 4 birds per km2 between dales (Game Conservancy Trust, 1997). .
Waders
The associations between snipe and curlew and hill-edge habitats appear to be of long standing. Historical accounts imply that rough grazings on the hill-edge in the Pennines and Lake District were an important habitat for breeding snipe at the end of the nineteenth century (MacPherson, 1892; Nelson, 1907). The curlew was considered to be a moorland breeder but small numbers were recorded nesting in enclosed pastures on the hill-edge. Contemporary information on the status of redshank and lapwing is less specific. Redshank Tringa totanus were apparently very scarce as a breeder in the uplands of Lakeland and Yorkshire at the turn of the 19th and 20th centuries whereas lapwings were so widespread and numerous as a breeder in Yorkshire that they did not merit specific comments about their breeding habitats.
The key study on breeding waders of the hill-edge is that undertaken by Baines (1988a, 1988b, 1989, 1990b). Baines (1988b) examined how five breeding species (lapwing, redshank, curlew, snipe and oystercatcher Haematopus ostralegus) used habitat mosaics of pastures and meadows on the hill-edge, in parts of the northern Pennines (Upper Teesdale and Eden Valley), and paid particular attention to the effects of agricultural improvement. There were very marked differences in the densities of breeding waders supported by unimproved and improved fields (Table 7.6). Densities of lapwing, redshank, snipe and curlew in pastures were much higher in unimproved fields than in improved fields. The effects of improvement were less pronounced in meadows; only lapwing and snipe bred at higher densities in unimproved fields than in improved fields. Similar differences in the proportions of fields occupied by lapwing, redshank, curlew and snipe were observed between field types and the categories of agricultural improvement. Though the association with improvement was generally negative, oystercatchers tended to prefer improved fields.
137 Table 7.6. Densities (mean pairs 100ha-1 + standard error) of breeding waders on hill- edge habitats in parts of the northern Pennines (Upper Teesdale & Eden Valley) in relation to grassland type and agricultural improvement (after Baines, 1988b). Species Pastures Meadow Unimproved Improved Unimproved Improved Lapwing 53.9+4.6 14.1+2.6 59.5+7.9 26.2+4.9 Redshank 6.2+0.9 1.2+0.5 4.8+1.4 2.6+1.3 Snipe 15.6+3.2 0.1+0.1 6.1+2.1 0 Curlew(1) 10.9+1.5 2.0+0.5 9.8+3.4 6.3+1.8 Oystercatcher 0 0.1+0.1 0 1.1+0.6 Notes: (1) - data for Eden Valley only.
The effects of agricultural improvement became even clearer when the birds’ use of groups of fields was compared using regression analyses. The proportion of fields within groups that was occupied by lapwing and snipe respectively decreased as the proportion of grassland that had been improved increased. In areas where all fields had been converted to improved pasture, the regression equations predicted that the proportion of fields occupied by lapwing densities was a quarter of that in areas without any improvement, whereas snipe were predicted to disappear altogether when more than 80% of fields in a group had been improved. Equivalent relationships with redshank and curlew also tended to be negative but they were not significant. As the effects of improvement were not equally severe for all species, the composition of the species assemblages changed with agricultural improvement. Improved pastures contained proportionately fewer snipe and proportionately more lapwings than unimproved pastures. However, the difference in the composition of species assemblages of waders on meadows was not significant.
The study by Baines focussed on the differences between improved and unimproved grasslands on the hill-edge and it did not compare bird densities on enclosed grasslands with those of adjacent unenclosed moorland. A concurrent study of habitat use by breeding waders in Mynydd Hiraethog, an upland area of North Wales did, however, cover the full range of habitats from unenclosed moorland to enclosed and improved farmland in valleys (Bain, 1987). Dunlin Calidris alpina and golden plover Pluvialis apricaria were restricted to remote, dense coarse grassland on the highest ground (above 400m). Curlew and snipe occupied damp coarse grassland on unenclosed moorland as well as on the hill-edge. Lapwings occupied a range of habitats, including damp enclosed pastures, ploughed land and damp coarse grassland below 350m. Finally, redshank were restricted to very wet coarse grassland in valleys. All species tended to avoid the dry improved pastures, which had been reseeded with Lolium perenne, as was the case in the Pennines.
More recently, Wightman (2001b) compared densities of breeding waders on unenclosed moorland with those of enclosed ‘in-bye’ land in the North York Moors National Park. Golden plover only nested on unenclosed moorland whereas curlew densities on in-bye land were more or less the same as those on unenclosed moorland. In contrast, densities of lapwing on in-bye land were much higher than those on unenclosed moorland. Several other surveys of breeding waders covered unenclosed moorland and hill-edge habitats (Table 7.1) but, as counts for the various habitats were not presented separately, no comparison is possible without reprocessing the data.
138 Passerines
Two separate studies of twite and ring ouzel respectively have identified close associations between the breeding distributions of these species in specific areas and hill-edge habitats. The distribution of twite on unenclosed moorland in the south Pennines was analysed by Brown et al. (1995). Twite tended to occur most frequently close to the hill-edge. The selection of nest sites on moorland near the hill-edge was attributed to the requirement by breeding adults to feed in pastures and meadows (see below). In the North York Moors National Park, the distribution of the ring ouzel was closely associated with a narrow margin of land between the 250m contour and the moorland plateau (Hutchinson, 2001). It was noted that this margin is usually less than 250m wide and is mostly uncultivated land lying between the intake (=inbye land) and boundary of unenclosed moorland.
Finally, in this review of individual species studies conducted on the hill-edge, reference must be made to the yellow wagtail Motacilla flava flavissima. Though it is a generally a bird of the lowlands in Britain, breeding populations occupy several of the Pennine Dales, at relatively high densities (see density map in Tyler, 1993). Studies of breeding yellow wagtails in the Pennine Dales have shown that a high proportion of nests were situated in upland hay meadows (ADAS, 1996). The proportion was consistently high between dales (71-86% of nests per study area). Yellow wagtails were recorded from the hill-edge habitat groups identified by the LIAL study of the Yorkshire Dales although the species was not confined to those groups (Curtis et al., 1991).
Summary
x Assemblages of breeding birds on the hill-edge have been identified from surveys of the uplands in parts of England and Wales. Distinctive assemblages of breeding species have been recorded from hill-edge habitats in the Pennines, the ffridd in Wales and Dartmoor. x Most species recorded from the hill-edge also occur in other habitats but some occur at higher densities in hill-edge habitats. Only two species were largely restricted to the hill-edge: black grouse and red kite. x The objectives and methodologies of the surveys of hill-edge birds varied between areas. Nonetheless, there is strong evidence that the composition of the species assemblages breeding in hill-edge habitats varied between regions. x Waders were the dominant species in the northern Pennines but comprised a relatively minor component of species assemblages on the hill-edge in Wales and SW England. x Passerines of scrub and woodland margins, especially whinchat, yellowhammer and tree pipit, were characteristic of hill-edge assemblages on the ffridd and on Dartmoor.
(ii) Are habitat mosaics within the hill-edge ecotone important for breeding birds?
The general preference by black grouse for the hill-edge was noted in the previous section. However, two quantitative surveys of habitat use by black grouse, undertaken
139 at sites in the northern Pennines by Baines (1994b) and Starling-Westerberg (2001), give a more detailed picture of the birds’ use of the mosaic of habitats that often occur on the hill-edge.
Baines (1994b) showed that black grouse from four study areas used heather moorland and bog, grass moor, rough grazing and inbye fields in spring and that they showed a strong preference for heather moorland and bog and rough grazings. In summer, the birds were recorded from fewer habitats (moor and bog, rough grazing and grass moor) and showed very strong preference for grasslands, particularly rough grazing, and largely avoided the heather moorland and bog that had been a preferred habitat in spring. This shift in habitat preferences during the breeding season implies that the availability of a combination of habitats is important.
A seasonal shift in habitat preferences during the breeding season was also recorded by Starling-Westerberg (2001) who used radio-tagged birds to establish home ranges and habitat preferences. All individuals preferred grassland habitats on the moorland margins and on the enclosed inbye land but the two sexes preferred different types of grassland. Males preferred marshy grassland whereas females preferred acid grassland. In summer, however, marshy grassland replaced acid grassland as the preferred habitat for breeding females, whereas marshy grassland continued to be the preferred habitat for males. Females with young subsequently moved either to habitats where rushes (Juncus spp.) were locally abundant or to hay fields. These seasonal shifts in habitat preferences again imply that the close proximity of habitats was important. In both studies, however, the evidence for the importance of habitat mosaics is largely inferential. There is scope for a comparison of the habitat composition of home ranges with that of equivalent areas not used by black grouse, and for an analysis of seasonal variation in the habitat preferences of individual birds.
The RSPB study of songbirds in the ffridd of central Wales highlighted the importance of the transition from open habitats to scrub and scrub-woodland for songbird communities (Hobson, 1985; Garnett, 1988). Bracken stands intermixed with scattered gorse bushes and trees were particularly important for whinchat, yellowhammer and tree pipit (Bibby, 1988; Garnett, 1988, Garnett et al., 1988; Bates, 1992).
The importance of habitat mosaics to whinchats has been investigated in several studies. Garnett et al. (1988) showed the importance of habitat mosaics within the home ranges of individual pairs breeding on ffridd in Wales. Perch hunting was the most frequently used foraging technique. Whinchats perched mainly on bracken stems and flew down to capture invertebrate prey from adjacent areas of turf grazed by sheep. The optimum mix of habitat patches was 70-80% Festuca/Agrostis grassland, 20-30% bracken and 5-9% gorse. Bracken stands provided cover for nesting, especially when litter was available, but the quality of the feeding territories around each nest appeared to be negatively correlated with bracken cover. Pairs nesting in dense stands of bracken had to fly further to feed than those nesting in sparser stands. In the North York Moors, whinchats occupied habitats containing extensive stands of bracken but tended to select areas that contained greater areas of acid grassland and rushes (Juncus spp.), and a greater diversity of vegetation, than would have been expected by chance (Allen, 2001).
140 Summary
x Black grouse exploited mosaics of habitats on the hill-edge. However, it is not yet clear whether the birds select particular areas of hill-edge because of the habitat mosaics that they contain. x Yellowhammer, tree pipit and whinchat were shown to be associated with habitat mosaics in the ffridd lands of Wales. x Behavioural studies showed that the quality of whinchat territories was related to proximity of particular habitat patches – bracken and grazed Festuca/Agrostis grassland.
(iii) Are elements of hill-edge habitat important for species nesting on adjacent moorland?
Local breeding populations of at least six species that nest on open moorland in Britain may be dependent upon the availability of hill-edge habitats during the breeding season. The species are golden plover, curlew, ring ouzel, twite, merlin and golden eagle. The evidence for the use of hill-edge habitats by each species is assessed against the following criteria:
1. Observed use of hill-edge habitats. 2. Linkage between individuals nesting on moorland and feeding on hill-edge habitats. 3. Evidence of correlations between nesting densities and availability of hill-edge habitats, which suggest that the latter is a limiting factor. 4. Experimental evidence that the availability of hill-edge habitats limit the size of populations breeding on adjacent moorland
Golden Plover (Pluvialis apricaria)
Golden plovers Pluvialis apricaria are widely distributed throughout the uplands of Britain where they nest on unenclosed moorland, especially dwarf-shrub heath (Ratcliffe, 1976). However, it has long been known that golden plover feed but do not nest on pastures adjacent to moorland (Gilbert & Brook, 1924, cited in Ratcliffe, 1976). Observers in four areas in the Scottish Highlands (Nethersole-Thompson, Goode and Humphrey; cited in Ratcliffe, 1976) showed independently that birds flew into pastures from, and departed in the direction of, moorland where golden plover were breeding.
Confirmation that plovers observed feeding on upland pastures were nesting on adjacent moorland was supplied by Parr (1980) who carried out a study in Aberdeenshire using colour-ringed birds. Pastures bordering moorland were used for feeding prior to, and after, the birds had established their breeding territories but they were not used after chicks had hatched. Adult golden plover that were feeding on the pastures took earthworms and other small prey. The use of hill-edge pastures by golden plover breeding on moorland has been further clarified by radio-tracking studies of individual birds nesting on peatlands in Sutherland (Whitfield, 1996), the north Pennines (Whittingham et al., 2000) and the south Pennines (Pearce-Higgins, pers. comm.). Whittingham et al. showed that, on average, radio-tagged adults with
141 nests spent proportionately more time feeding in pastures than on moorland. However, moorland was preferred after the chicks had hatched. Adult golden plover commuted to feed in pastures up to 4 km from their nests and up to 2 km from the moorland edge. In Sutherland, golden plover nesting on bogs tended to fly to fields nearby though birds from one bog flew to a field 11 km from their nest site (Whitfield, 1996).
Parr (1980) and Whitfield (1996) noted that the plovers’ use of grass fields adjacent to moorland was selective while Parr also observed that some parts of fields were preferred over others. Whittingham et al. (2000) demonstrated that field use by golden plovers breeding in an area of the North Pennines was strongly and positively correlated with a molehill index that reflected earthworm abundance. Field use was also positively correlated with the number of hummocks though this relationship was relatively weak. In addition, large fields were more likely to be used than small ones and fields far from roads were more likely to be used than those close to roads. However, field area and proximity to roads were highly correlated and it was not clear which variable the birds were responding to.
Hudson (1988) has shown that the availability of grassland adjacent to blanket bog or dwarf shrub heath overlying peat may increase the period that invertebrates are available to upland birds and may also provide critical food types, such as earthworms. In the Scottish Highlands, crofters and hill farmers have created agriculturally rich grasslands adjacent to moorland that is poor in nutrients. Hudson (1988) suggested that their creation has had a positive effect on the distribution and/or density of moorland bird species that feed on macro-invertebrates that occur on the ground or upper soil horizons.
A key issue is whether or not the availability of hill-edge pasture limits the densities of golden plover nesting on moorland? If this factor is limiting, then the breeding densities of golden plover should be higher on moorland close to pastures than on moorland distant from pastures, all other factors being equal. The evidence for such a relationship is of variable quality and is also contradictory. Using field observations from four areas in Scotland (East and West Sutherland, Orkney and Speyside), Nethersole-Thompson (cited in Ratcliffe, 1976) suggested that breeding densities of golden plover were higher on moorland close to adjacent farmland (worked and abandoned) than on uniform moorland. Parr (cited in Ratcliffe, 1976) also suggested that densities were higher on moorland margins bordering farmland than in the centre of grouse moors. However, neither set of observations allowed for possible confounding effects of other habitat and land management variables. A more rigorous multivariate analysis of the relationships between golden plover distribution in the south Pennines and a range of habitat variables did not show any correlation with hill- edge farmland (Haworth & Thompson, 1990). The lack of an association was attributed to the fact that pastures in the south Pennines study area tended to be too steep and enclosed to be suitable for golden plovers.
If the correlations suggested by Nethersole-Thompson and Parr reflect a causal relationship, then the creation of new grasslands on the margins of moorland, where previously there had been none, should result in local increases in the breeding densities of golden plover on moorland. This prediction is supported by data from an experiment in which artificial crofting fields of 1-2 ha were created from moorland in Speyside, Scotland (Hudson, 1988). There was an overall increase in the spring
142 density of golden plover over five years to a mean of 6.7 birds km-2 in the areas containing the artificial crofting fields, compared with only 1.5 km-2 on the control areas. However, at another site in the eastern Highlands of Scotland, Glen Esk, where heather moorland was replaced by grassland, golden plover numbers did not respond positively but declined to zero (Jenkins & Watson, 2001). As golden plovers also disappeared from an adjacent area of moorland that had not been converted to grass, it is unlikely that the population changes were due to the conversion of heather moorland to grass. Unlike the experiment in Speyside, the treatments in the Glen Esk plots were not replicated, so less reliance may be placed on the significance of the observations from Glen Esk.
It is likely that the limiting effects of the availability of hill-edge pasture on the breeding density of golden plover on moorland may vary between areas. Though Whittingham et al. (2000) showed that most breeding adults commuted from their moorland nest sites to feed on pasture, the male of one pair did not. The territory of this pair differed from those of the others in that it contained calcareous grassland that supported relatively high densities of earthworms. These observations suggest that golden plover will feed close to their nests, when food supplies permit. They also imply that the availability of hill-edge farmland may be less important in fertile uplands overlying calcareous rocks than in relatively infertile uplands overlying acidic rocks. There is an interesting link between this inference and the observation by Ratcliffe (1976) that nesting densities of golden plover were highest on moorland overlying calcareous rocks. Further evidence for geographical variability in the importance of hill-edge pasture comes from the Scottish Highlands and Islands, where the use of grass fields bordering open moorland varied between areas. Three separate studies showed that although golden plover breeding in the flow country of Sutherland and Caithness made extensive use of hill-edge pastures, those breeding on peatlands on the Isle of Lewis tended to remain near their nests during the incubation period, whereas golden plover nesting on montane plateaux did not use hill-edge pastures at all (Whitfield, 1996).
Curlew (Numenius arquata)
The curlew is a widespread breeder in the uplands of Britain (Grant, 1993). Curlew nest in a variety of upland habitats including unenclosed moorland as well as rough grazing and enclosed grassland on the hill-edge.
Individuals from some breeding populations of curlew that nest on moorland rely on other habitats as feeding sites. Using radio-tagged birds, Robson et al. (2002) showed that curlews nesting on moorland in Upper Teesdale foraged in pasture, meadows and rough grazing on the hill-edge. The birds showed preferences for some fields over others. Fields were more likely to be used if they were large and close to the moorland edge. There are no other examples from England or Wales but curlew breeding on moorland in Orkney used improved grasslands as feeding sites (Grant unpublished, cited in Robson et al., 2002).
The relationship between the distribution of curlew nesting on moorland in part of the southern Pennines (Forest of Trawden) and variables describing the moorland and hill-edge habitats has been modelled by Haworth & Thompson (1990). However, this model provided no evidence to suggest that the distribution of curlew was at least
143 partially correlated with the availability of pastures on the hill-edge. Rather, curlew tended to occupy high plateau areas and avoid the hill-edge. Unlike the golden plover, no manipulative experiments have been carried out to evaluate the response of local densities of curlew nesting on moorland to the introduction of hill-edge grasslands.
Twite (Acanthis flavirostris)
Breeding twite are distributed throughout upland Britain but their densities are highest in areas of low intensity agriculture in northern Scotland and on heather moorland in the south Pennines (Jardine & Reid, 1994). The species extended its breeding range into Wales between 1968-72 and 1988-1991 (Jardine & Reid, 1994).
Our knowledge of the breeding ecology of twite in England and Wales is largely restricted to the south Pennines (Orford, 1973; McGhie et al., 1994; Brown et al., 1995; Reed, 1995). This area supports the largest known concentration of breeding twite in England and Wales (Jardine & Reid, 1994; Brown et al., 1995). Nests tend to be placed on open moorland, either in mature Calluna, or in bracken, but the breeding adults prefer to feed in hill-edge habitats, especially hay meadows and unimproved pastures. In three study areas near Halifax, the distance between nest sites and feeding grounds varied from 100 m to c. 2.6 km though most nests were more than 500 m from the birds’ feeding grounds (McGhie et al., 1994). During the breeding season, adult twite fed mainly on the seeds of dandelions Taraxacum (vulgaris) agg. , the grass Poa annua, and sorrel Rumex acetosa. The birds’ diet varied through the breeding season according to seed availability. Broadly speaking, dandelions were preferred early in the season (mid-May onwards), followed by Poa in late May and early June. The birds then switched to sorrel after the seeds had ripened in mid-June. The birds’ selection of fields on the hill-edge was positively correlated with the densities of their food plants (McGhie et al., 1994).
Though pastures and hay meadows on the hill-edge comprise important feeding habitats, there is no direct evidence for a correlation between the availability of hill- edge grasslands and the distribution of twite breeding on adjacent moorland. Haworth & Thompson (1990) modelled the relationship between twite distribution, at the 0.5 km square scale, and habitat features on open moorland and its fringes in part of the southern Pennines. The models indicated that the distribution of twite was strongly associated with Calluna and bracken but not with hill-edge grasslands that provide feeding sites. However, the lack of a relationship with hill-edge grasslands should be viewed with caution because it is possible that the variable selected by Haworth and Thompson to describe hill-edge grasslands was too broadly based and included grassland habitats never used by twite. Also, given the distances flown by twite between their nests and feeding sites, the sampling scale of 0.5 km square may have been too small to pick up an effect of hill-edge habitat availability. A follow-up modelling exercise was carried out on a much larger area of the south Pennines, using data on twite distribution, at the 1 km square scale (Brown et al., 1995). However, the availability of hill-edge pastures and hay meadows was not measured. The model yielded an interesting finding that many of the moorland 1km squares that held no twite were predicted to be highly suitable for the birds. After ruling out sampling effects, Brown et al. (1995) suggested that the false positive predictions of the model
144 implied that twite do not occupy otherwise-suitable moorland if appropriate grassland feeding habitats are not available nearby.
At present, no experimental data are available to test whether or not the availability of hay meadows on the hill-edge limits the numbers of twite nesting on adjacent moorland. However, this situation may change if population changes following the introduction of Countryside Stewardship agreements targeted at twite (Defra, 2001; RSPB, 2002) are closely monitored and compared with control plots.
Ring ouzel (Turdus torquatus).
The ring ouzel is a scarce breeding species that is widely distributed through the uplands of Britain (Wotton et al., 2002). Nests have been recorded from moorland and hill-edge habitats (Flegg & Glue, 1975). Until recently, this was one of the least studied breeding species in Britain but research by Burfield (2002) in Scotland has clarified the habitat requirements of breeding ring ouzels. In two widely separated study areas (Glen Esk in the Eastern Highlands, and the Moorfoot Hills in SE Scotland), breeding ring ouzels tended to occupy areas containing a mix of dwarf shrub heath and grass. Breeding adults tended to place their nests in heather but foraged on grass moor or pasture for invertebrate prey, especially earthworms. The proportion of grass cover in home ranges tended to be higher than would have been expected if the ranges had been selected at random. In Glen Esk, foraging adults showed a marked preference for grazed pasture (a hill-edge habitat) and home ranges tended to contain proportionately more grazed pasture, by area, than would have been expected by chance. This finding was not duplicated in the study area in the Moorfoot Hills but another study in the Pentland Hills, which are close by, showed that hill- edge pastures were an important feeding habitat for ring ouzels nesting on moorland (Poxton, 1986). Moreover, anecdotal information from a survey of ring ouzel distribution in the North York Moors suggested that closely cropped areas of grassland on the hill-edge were the main source of invertebrates for breeding ring ouzels (Hutchinson, 2001). These findings suggest that the importance of pastures as a food source for breeding ring ouzels is widespread.
Is there any evidence that the availability of hill-edge pastures limits breeding densities of ring ouzels on moorland? A discriminant analysis of the relationship between the breeding distribution of ring ouzels in part of the south Pennines and a range of habitat variables showed positive associations not only with heather and bracken (their nesting habitat) but also with the availability of pastures on the hill- edge (Haworth & Thompson, 1990). It was suggested that the association with pasture reflected the species’ preference for habitats with relatively abundant soil invertebrates, especially earthworms close to the nesting site. However, there is no experimental evidence to determine whether or not the correlation between ring ouzel distribution and the availability of hill-edge pastures signified a causal relationship.
Merlin (Falco columbarius)
In upland Britain, merlins generally nest on open moorland in trees, on small crags and isolated rocks or on the ground in heather (Newton et al., 1978; Bibby, 1986; Brown & Stillman, 1998), though some nest in upland conifer plantations (Parr, 1991;
145 Little & Davison, 1992). Bibby (1988) has noted that hill-edge covered by bracken comprises important hunting grounds for some pairs of merlins.
The evidence that merlins nesting on moorland rely upon hill-edge habitats for their prey is largely indirect. Using data from a breeding population in Wales, Bibby (1986) showed that the extent of farmland between 1 and 4 km from the nest site varied between nests, and that nests containing five eggs tended to be surrounded by more farmland than those nests containing four eggs. Bibby suggested that this was because farmland contained a greater variety, and higher densities, of avian prey than moorland. Bibby (1987) subsequently showed that the diet of merlins in his Welsh study area, in spring, contained a relatively high proportion of non-moorland birds that implied that some merlins were hunting beyond the moorland boundary. Pairs with the most varied diets were those with the most farmland with 2-4 km from the nest. These pairs also laid the largest eggs. As equivalent datasets are not available from other areas, it is not known whether or not the relationships identified from the Welsh study area apply generally.
The evidence for a correlation between the distribution of merlins on unenclosed moorland and the availability of hill-edge habitats is equivocal. Haworth and Thompson (1990) showed that in an area of the south Pennines, the presence of merlins was positively correlated with bracken cover, which tends to be highest on moorland margins. However, it is not clear whether this correlation relates to merlins nesting in bracken or to birds that were nesting in heather, on trees or rocky outcrops and which were hunting over bracken-covered ground. There is no experimental evidence for or against the limiting effect of hill-edge habitats on the densities of merlins breeding on moorland.
Given the distribution of nest sites recorded from moorland areas that have been well studied (Newton et al., 1978; Bibby, 1986; Brown & Stillman, 1998), it is unlikely that the distribution of merlins breeding on moorland is limited by the availability of hill-edge habitats. However, as Bibby (1986, 1987) showed in Wales, the quality of individual territories, in terms of potential food availability and its effects on egg volume and clutch size, appears to be dependent upon the proximity of farmland.
Other species
Two other diurnal birds of prey that breed on unenclosed moorland, golden eagle (Aquila chrysaetos) and hen harrier (Circus cyaneus), may also rely upon hill-edge habitats. The evidence comes from Scotland where both species are much more numerous than in England or Wales.
Marquiss et al. (1985) studied an isolated breeding population (4 pairs) of golden eagles in SW Scotland. They showed that breeding pairs that had access to low altitude moorland and moorland fringe, where avian prey tended to be relatively abundant, bred more successfully than pairs with home ranges that contained only a small proportion by area of this combination of habitats. The failure of two pairs to breed, and of a third to raise young, was attributed to afforestation of low altitude hill ground.
146 The evidence that hen harriers rely upon hill-edge habitats during the breeding season is very fragmentary. Hen harriers nest in heather on open moorland (Redpath et al., 1998) but Redpath (1992) showed that adult harriers in study areas in Speyside and Perthshire preferred to hunt along the margins of habitat patches. In Orkney, where the hen harrier is a comparatively numerous breeder, recent population declines there have been attributed to agricultural improvement of farmland bordering moorland (Meek et al., 1998).
Table 7.7. Summary table of evidence of use of hill-edge habitats by bird species nesting on adjacent moorland. Species Observed use of Use of marked Models Experimental hill-edge birds or direct identifying evidence habitats observation to relationship link feeding & between bird nesting habitats distribution and availability of hill-edge habitats Golden plover + + - +/- Curlew + + - ? Ring ouzel + + + ? Twite + + -/+ ? Merlin + ? ? ? Golden eagle + + ? (+) Hen harrier + ? ? ? Key to symbols: + = supporting evidence; - = contradictory evidence; ? = no relevant information
Summary
x The local distributions of six moorland species, and a possible seventh, the hen harrier, showed linkages with the hill-edge (Table 7.7). x It was established that individuals of five species that were nesting on moorland were also feeding on hill-edge habitats. x Supporting evidence for the limiting effect of hill-edge habitats was available for only two species, golden plover and twite but a second model for twite gave contradictory evidence. x Experimental evidence of the limiting effects of hill-edge habitats was available for only one species, the golden plover. A manipulative experiment upheld the prediction that the availability of pasture adjacent to heather moorland was limiting local densities of golden plover nesting on the moorland. However, a ‘natural’ experiment at a second site provided contradictory evidence. In the case of the golden eagle, a ‘natural’ experiment gave supportive evidence for the limiting effect of hill-edge habitats.
(iv) importance of hill-edge habitats for birds outside the breeding season
Comparatively little has been recorded about the use of hill-edge habitats by birds outside the breeding season. This may be partly because many of the species that rely on hill-edge habitats during the breeding season, such as golden plover and ring ouzel, move elsewhere during the winter. The bulk of the information that is available relates to the two most characteristic hill-edge species, black grouse and red kite, which are residents.
147 The most detailed information on habitat use by black grouse outside the breeding season comes from two year-round studies of birds at sites in the northern Pennines. Baines (1994b) recorded that, in late summer (mid-July to mid-August), black grouse were recorded from three habitats, moor and bog, grass moor and rough grazing, but showed a strong preference for rough grazing. In autumn and winter, birds occurred in five habitats – heather moor and bog, grass moor, rough grazing, inbye fields and woodland - but heather moorland and inbye fields were preferred over the other habitats.
A follow-up study by Starling-Westerberg (2001) used radio-tagged individuals to record the birds’ use of five types of habitat – woodland, marshy grassland, species poor neutral grassland, acid grassland, acid/neutral flush and heather moor and bog. In autumn, marshy grassland and acid neutral flush were preferred. The preference by males for marshy grassland was extremely marked. In winter, however, the birds used all five habitats available and did not show a marked preference for any of them. The strongest preference was for woodland. About 11% of radio-locations of females were from young Norway spruce Picea abies plantations. Though the detail of the habitat preferences differs between the two studies, both highlight the importance of combinations of habitats that tend to occur on the hill-edge.
The studies by Baines and Starling-Westerberg were undertaken in relatively treeless areas and there is some evidence that the birds’ habitat preferences are different in more wooded landscapes. In three study areas on the fringes of the Eastern Highlands in Scotland, which contained moorland bordered by commercial conifer plantations and also some woods comprising native deciduous trees, black grouse preferred tall- heather and other tall vegetation. Some bird fed on trees in snow free periods but all did so in deep snow (Parr & Watson, 1988). In Wales, Cayford (1990) studied habitat selection by, and home range and diet of, black grouse in commercial conifer forest that bordered open moorland, using radio-tagged individuals. The birds preferred thinned middle-age plantation, patches of dry moorland and linear semi- natural habitats along tracks and roads and in forest rides, whereas they avoided mature forest, uncultivated agricultural fields and grassland. A comparative analysis of black grouse diet through the year implied that, in winter, the birds were feeding mainly on open moorland where they foraged on plant matter taken from heather Calluna vulgaris and bilberry Vaccinium myrtillus. The Scottish study indicates the importance of woodland on the hill-edge during winter, especially in severe weather conditions but, in Wales, the birds did not show any marked preference for habitats, or mosaics of habitats, that are typical of the hill-edge.
The hunting behaviour of red kites in central Wales has been monitored by Walters Davies & Davis (1973). Observations made from selected vantage points showed that a high proportion of birds remained in the ffridd and adjacent habitats throughout the year. In late summer and autumn, kites hunted for prey primarily on the ffridd and sheep walk and searched sheep walk that is remote from the ffridd more frequently than at any other time of year. In winter, the birds wandered more widely and spent more time hunting the lowlands and valley farms. It was not possible to track the movements of individuals, however, because the birds had not been marked either with wing-tags or radio transmitters.
148 Reed (1995) investigated habitat use by twite in part of the Pennines during and after the breeding season. He showed that post-breeding flocks of twite preferred to forage in uncut hay fields in July before switching to pastures that were lightly grazed by cattle or horses. Pasture was the most frequently used feeding habitat until the birds left the breeding area in October.
The remaining information on the use of hill-edge by birds outside the breeding season is anecdotal and very fragmentary. It is believed that a local population of chough prefer to forage on ffridd grasslands in an area of Snowdonia outside the breeding season but the degree to which the birds rely on that habitat is not known (CCW, pers. comm.)
Summary
x Little is known about the importance of hill-edge habitats to birds outside the breeding season compared with the breeding season when most studies of hill- edge birds have been carried out. x Most is known about the habitat requirements of the two most characteristic hill-edge species, the black grouse and red kite, which are resident. x Some, though not all, local populations of black grouse rely on habitats that are found exclusively on the hill-edge. x Red kites in central Wales hunt in the ffridd during the late summer and autumn but wander more widely during the winter when they use a much wider range of habitats, including improved farmland in the valleys below the ffridd. x Twite exploit uncut hay fields in July, after young have fledged, but then move onto lightly grazed pastures which remain the preferred foraging habitat until the birds depart in October.
Effects of habitat change on birds of hill-edge habitats
The aim of this section is to assess the scale and extent of population changes of birds in hill-edge habitats, and to determine to what extent those changes are due to changes in land use on the hill-edge, particularly agricultural improvement and afforestation.
Towards the end of the nineteenth century, several observers suggested that the enclosure of land on the margins of moorland, and the agricultural improvement that followed, was having a deleterious effect on a variety of bird species using hill-edge habitats (Buckley & Harvie-Brown 1891; MacPherson, 1892). Subsequently, Ratcliffe (1990) summarised what was then known about upland bird populations in Britain. He concluded that populations of a significant proportion of upland species had been affected by habitat changes on unenclosed hill ground (=moorland) and marginal land (=hill-edge). Most, but not all, of the population changes were negative (Table 7.8). The principal drivers of habitat change were considered to be agricultural improvement of unenclosed moorland and hill-edge habitats, and afforestation. Agricultural improvement entailed drainage, ploughing, fertilising, re-seeding, application of herbicides, increased stocking and, on unenclosed moorland, enclosure. A similar list of factors was compiled by Shrubb et al. (1997) in their review of land use changes in Wales and the consequences for bird populations.
149 Table 7.8. Population changes of upland bird species that use hill-edge habitats in relation to habitat change since 1900 (after Ratcliffe, 1990). Species Improvement Reclamation Afforestation Notes of marginal of hill ground land Yellow -? Wagtail Redshank - Cuckoo -? - Chough -? - Skylark -? - Meadow Pipit -? - Lapwing - +- Curlew - -- Snipe - -- Oystercatcher + +? Black Grouse -? +/- Increase in early stages of forest development followed by subsequent decline as forest canopy closes. Whinchat -? -+/-Increase in early stages of forest development followed by subsequent decline as forest canopy closes. Golden Plover -- Merlin -- Hen Harrier -+/-Increase in early stages of forest development followed by subsequent decline as forest canopy closes. Ring ouzel -- Twite - Stonechat - Wheatear - Key to symbols: - = population decline attributed to specified factor, -? = population decline probably due to specified factor; + = population increase due to specified factor; +? = population increase probably due to specified factor; +/- = increase followed by decrease.
Evidence of population changes
A range of datasets, including many that have been collected or published since the reviews by Ratcliffe and Shrubb et al., have been scrutinised to assess the scale and extent of changes in bird populations on the hill-edge.
The assessment draws mainly on four sources of data:
1. Mapped data from the BTO breeding bird atlas surveys in 1968-72 (Sharrock, 1976) and, again, in 1988-91 (Gibbons et al., 1993), and surveys of nationally scarce species, such as the ring ouzel (e.g. Wotton et al., 2002). 2. The long series of regional surveys of upland breeding birds that has been undertaken by the RSPB and others since in the mid-1980s, which include some repeat surveys (e.g. McKnight et al., 1996; Babbs, 1998; Small et al., 1998). 3. A small number of plots sampled for the BTO Common Bird Census (e.g. Fuller et al., 2002). 4. Shooting bag records for game birds (e.g. Baines & Hudson, 1995).
The two characteristic species of the hill-edge are the red kite and black grouse. The relict population of red kites in the ffridd in central Wales has been monitored since the late 19th century (Davis, 1993). Twenty-one territories with pairs were recorded
150 between 1891-95 but, by 1936-40, only 10 territories were occupied. The population recovered gradually, thereafter, so that during 1986-90, 104 territories contained birds (Davis, 1993). By 1999, the population had further increased to 181 breeding pairs and an estimated 228 pairs overall (Ogilvie & the Rare Breeding birds Panel, 2001). A more detailed population analysis for 1951-1980 is given by Davis & Newton (1981).
Given the close association between black grouse and habitats on the hill-edge, population changes on the hill-edge will be reflected in regional and national population statistics. The longest running datasets are shooting bags that give an indication of population trends since the 1920. Annual shooting bags from 58 grouse moors showed a very marked reduction in the late 1930s from which there was no subsequent recovery (Hudson, 1989; Baines & Hudson, 1995). Annual bags in the 1920s were, on average, c. 0.4 birds shot per km-2 but, by the early 1980s, they had fallen to c. 0.05 birds shot per km-2. Comparison of the two breeding bird atlas surveys of Britain and Ireland show that a major contraction in range occurred between 1968-72 and 1988-91 (Hudson & Baines, 1993). The number of 10km squares in Britain from which black grouse were recorded decreased from 603 in 1968-72 to 432 in 1988-91, a 28% reduction. The decrease is even larger if the comparison is restricted to records with evidence of breeding (463 to 278, a reduction of 40%).
Recent estimates of the population of black grouse in Britain show a continuing decline from 25,000 (95% confidence limits = 13,800-36,700) in the early 1990s (Baines & Hudson, 1995) to 6510 (95% confidence limits = 5000-8100) in 1995-6 (Hancock et al., 1999). Decreases have been particularly severe in the most southerly breeding populations and the local breeding populations in Dartmoor and Exmoor are now extinct (Hudson, 1989). In Wales, 232 males were recorded in 1986 (Grove et al., 1988) but only 153 males were recorded in a repeat survey in 1995 (Williams, 1996), a 34% decrease in nine years. In the Staffordshire part of the Peak District, the number of displaying males decreased from 55-65 in 1973-75 to 19 in 1985 (Lovenbury et al., 1978; Yalden, 1986), and then to six birds in 1995 and 1996 (Reed, in Hancock et al., 1999). In the 19th Century, black grouse apparently bred at high densities on the Staffordshire Moors (Hudson, 1989) but the risk of local extinction now appears to be high.
Waders
Few counts of waders were made on the hill-edge prior to 1960 (e.g. Nethersole- Thompson, 1961). The longest series of counts are those undertaken as part of the Common Bird Census (CBC), which commenced in 1962. Fuller et al. (2002) have analysed the population trends of ground-nesting birds, including waders, on two hill- edge farms in the northern Pennines. A farm in Rossendale, Lancashire, was surveyed annually from 1968 to 1999, whereas the run of counts at the second site near Sutton-in-Craven in Yorkshire was slightly shorter. Here counts were made annually from 1972 to 1984 and a follow-up survey was carried out in 1999. Four species of wader that are characteristic of hill-edge habitats were present at the two sites: lapwing, redshank, curlew and snipe. Numbers of lapwing and snipe decreased to very low levels at both sites, and snipe disappeared from the site in Rossendale. Very small numbers of redshank were present at the Rossendale site throughout the survey period. Redshank were more abundant at the Sutton-in-Craven site initially but
151 numbers decreased very rapidly and the species had disappeared as a breeder by 1985. Curlew were present at both sites throughout. Their numbers varied between years but there was no obvious trend at either site.
A third CBC survey site was situated in Upper Nidderdale. It was visited annually between 1963 and 1969 and again in 1996 (Swindells, 1997). Snipe and redshank were present in small numbers in the 1960s but had disappeared by 1996. Lapwings were more numerous than either snipe or redshank and were still present in 1996 but in very reduced numbers (Table 7.9). No other waders were recorded.
Table 7.9. Changes in the numbers of breeding birds on hill-edge grasslands in Nidderdale, Yorkshire Dales between the 1960s and 1996 (after Swindells, 1997). Species 1963-69 (1) 1996 %change Snipe 2 0 -100 Lapwing 31 4 -87 Redshank 3 0 -100 Skylark 31 0 -100 Swallow 6 4 -33 House Martin 11 10 Meadow pipit 11 1 -91 Yellow Wagtail 8 0 -100 Pied Wagtail 2 4 +100 Note: 1 = mean numbers per year shown.
A series of surveys of uplands in England and one in Wales, undertaken by the RSPB, provide information about trends in breeding wader numbers over much larger areas of hill-edge habitat. Mynydd Hiraethog, in North Wales, the North Staffordshire Moors, Forest of Bowland, and Baldersdale and Lunedale were surveyed at least twice between 1984 and 1996 (Tables 7.10, 7.11). In contrast to the CBC studies, the RSPB surveys are relatively recent, each covers a different period, and two of the survey areas, Hiraethog and North Staffordshire Moors, included unenclosed moorland as well as hill-edge habitats. With these caveats, the surveys show that a general decline in lapwing numbers occurred in the four survey areas. Redshank numbers decreased in three of the four areas and ceased to breed in the two most southerly ones, Hiraethog and the North Staffordshire Moors. Trends between years in the numbers of curlew and snipe varied between areas. Oystercatchers were present in the two most northerly areas (Bowland & Baldersdale/Lunedale) and their numbers increased markedly in Baldersdale.
In SW England, waders were counted as part of two more general surveys of breeding birds on Dartmoor. The surveys were undertaken in 1979 and, again, in 2000 of behalf of the national park authority (Geary, 2000). Though they covered moorland as well as hill-edge habitats, curlew and lapwing showed associations with hill-edge habitats and the population estimates for these species are, therefore, relevant to this assessment. Between 1979 and 2000, numbers of curlew and lapwing decreased by 83% and 71-79% respectively. Both species had been declining on parts of Dartmoor since the 1940s (Dare & Hamilton, cited in Geary, 2000).
152 Table 7.10. Changes in the numbers of selected breeding bird species in North Staffordshire Moors between 1985 and 1996. Species 1985 1992 1996 % change (1) (2) (3) 1985-96 Hill-edge species Black Grouse 5 4 3 -40 Curlew 421 280 173 -59 Snipe 654 320 178 -73 Lapwing 206 128 85.5 -59 Redshank 5 0 0 -100 Whinchat 51 41 52 +2 Moorland species that feed in hill-edge habitats Golden Plover 12 4 1 -92 Ring Ouzel 61 18 5 -92 Twite 95 88 64 -33 Notes: (1) 1985 survey data are from Waterhouse (1985); (2) 1992 data are from Brindley et al. (1992); (3) 1996 survey data are from McKnight et al. (1996).
Table 7.11. Counts of waders from surveys of three upland areas that included hill-edge habitats. Hiraethog, North Wales Forest of Bowland Baldersdale& Lunedale (random squares) Species 1984 1994 % 1993 1998 % 1993 1999 % (1) (2) change (3) (4) change (5) (6) change Oystercatcher - - - 49 52 +6 76 136 +79 Golden Plover 7 2 -71 ------Lapwing 99 36 -64 193 134.5 -30 821 -18 671.5 Snipe 21 23 +10 15 5 -67 184 163 -11 Curlew 68 51 -25 153.8 +33 229 236 +3 115.5 Redshank 6 0 -100 14 -35 174 176 +1 21.5 Data sources: 1 = Bain, (1987); 2= Thomas & Young, (1994); 3= Campbell et al. (1993); 4=Babbs (1998); 5 = Shepherd (1993); 6 = Small et al. (1999)
Passerines
The three key species are ring ouzel, whinchat and twite.
The breeding range of the ring ouzel in Britain showed a substantial contraction between the breeding bird atlas survey in 1968-72 and the follow-up survey in 1988- 91. The number of 10km squares occupied in Britain decreased from 745 to 544, a decrease of 27% (Hill, 1993). A re-analysis of these data by region showed that there was 22% decrease in occupied 10km squares in northern England, a 35% decrease in Wales and a 47% decrease in SW England (Wotton et al., 2002). An unknown proportion of these birds will have been associated with the hill-edge.
Ring ouzels were still widespread in Wales and northern England in 1999 (Wotton et al., 2002) but their status as a breeder is now extremely tenuous in the Staffordshire part of the southern Pennines and in SW England. Numbers on the North Staffordshire Moors decreased by 92% between 1985 and 1996 (Table 7.10). In SW England, only 7-16 birds were estimated to be present in 1999 (Wotton et al., 2002).
153 This estimate is much lower than previous estimates from Dartmoor (35-45 breeding pairs during 1977-85) and Exmoor (12 pairs in 1996) (Wotton et al., 2002).
The number of 10km squares in Britain occupied by breeding whinchats decreased by 16% between 1968-72 and 1988-91 (Callion, 1993). Most of the losses were in the lowlands and, during the period 1988-91, the remaining populations attained their highest densities in the uplands of central Wales and the Cheviot, and to a lesser extent in the Pennines and the Lake District. The North Staffordshire Moors survey showed that there was no net change in numbers between 1985 and 1996 (Table 7.10) but, in general, this species is poorly monitored in the uplands.
The geographical range of breeding twite in Britain remained relatively stable between 1968-72 and 1988-91; the number of occupied 10 km squares decreased by 1.1% from 657 to 651 (Jardine & Reid, 1993). There was some evidence of redistribution in the Pennines between the two atlas survey periods and evidence of a slight increase in range. Seven 10 km squares occupied in 1968-72 were vacant in 1988-91, whereas 15 squares that had been vacant in 1968-72 were occupied in 1988- 91. Twite declined between 1975 and 1985 and disappeared as breeders from the long-running CBC sites in Rossendale and near Sutton-in-Craven (Fuller et al., 2002), while numbers decreased by c. 33% on the North Staffordshire Moors between 1985 and 1996 (Table 7.10).
The CBC sites in Rossendale, near Sutton-in-Craven, and in Upper Nidderdale, provide evidence of widespread declines in the numbers of several passerine species in the northern Pennines (Fuller et al., 2002; Swindells, 1997). Skylark numbers decreased at all three sites, and the species disappeared as a breeder from the hill-edge habitats in Upper Nidderdale (Table 7.9). Reed bunting were present at Rossendale and Sutton but their numbers declined to very low levels. Yellow wagtail disappeared from Upper Nidderdale (Table 7.9). Finally, meadow pipit numbers decreased to very low levels in Upper Nidderdale but they showed no obvious long-term trend at the other sites.
Summary
x A combination of data from breeding bird atlas data from 1968-72 and 1988- 91, BTO Common Bird Censuses, upland bird surveys organised by the RSPB, and shooting bag records have been used to track population changes in bird species of the uplands and hill-edge. x The coverage of data collection and its geographical precision varies considerably between areas but the evidence suggests that numbers of most hill-edge species have declined in most regions of England and Wales (Table 7.12). x Only red kite and twite showed significant increases.
154 Table 7.12. Summary of population changes in hill-edge birds since 1950 by region. based on BTO atlas data, CBC counts, RSPB upland bird surveys, and single species monitoring schemes. Species SW Wales Southern North York Northern Lake England Pennines Moors Pennines District Red Kite ĹĹ Black Grouse ĻĻ ĻĻ ĻĻ - ĻĻ Lapwing ĻĻ Ļ ĻĻ ? Ļ ? Redshank ? ĻĻ ? Ļ ? Snipe ? ? Ļ ? ĻĻ ? Curlew ĻĻ Ļ ĻĻ ? Ĺ-? Ring Ouzel ĻĻ Ļ Ļ ?? Whinchat Ļ ?- ? ? ? Skylark - ? ? ? Ļ ? Yellow Wagtail Ļ Twite ĹĻ ĻĹ Key to symbols: ĹĹ = evidence of widespread increase; Ĺ = local increase; ĻĻ = evidence of widespread decrease; Ļ = evidence of local decrease; ĻĹ = local decreases and local increases recorded from the same region; - = no net population change locally; ? = trend not identifiable from available data.
Evidence of effects of agricultural land improvement
Two complementary data sources have been used to look for evidence of the effects of agricultural land improvement on hill-edge and moorland bird populations. These are spatial comparisons of unimproved hill-edge habitats with those that have been recently improved, and the comparison of time-series of counts with concomitant data on changes to the farmland habitat.
Comparison of bird numbers in improved and unimproved areas
The key study is that by Baines (1988a, 1988b, 1989, 1990b), who compared numbers and breeding success of waders breeding on unimproved and improved hill-edge grasslands in the northern Pennines. Baines (1988b) identified six key changes in grasslands on the hill-edge due to agricultural improvement: (1) a lowering of the water table and a reduction in soil moisture, (2) increased homogeneity of swards due to removal of tussocks and hummocks, (3) a reduction in species richness of higher plants, (4) increased productivity of grass fields (grass yields and/or livestock densities), (5) changes in abundance of invertebrate taxa, and (6) a reduction in organic content of soil and increased pH.
Comparisons of bird densities and the proportion of occupied fields between improved and unimproved grasslands indicated that improvement had a negative effect on four species: lapwing, snipe, redshank and curlew. The effect was most marked in the case of lapwing and snipe and was consistent across grassland types (pasture and meadow) and at two spatial scales (individual fields and groups of fields). The effects were more extreme for snipe than for lapwing. Snipe were predicted to disappear from groups of fields if more than 80% of the grassland by area was improved. Curlew and redshank also occurred at higher densities on unimproved pastures than improved pastures but the difference on meadows was not significant.
As snipe were not present in most improved fields, it is possible that the conversion eliminated the habitat features that attracted the birds to settle. Baines (1988b)
155 attributed the disappearance of snipe to drainage alone. Extensive Juncus cover in a field is a good indicator of a high water table and densities of snipe closely followed Juncus densities. Juncus may also provide nesting cover for snipe. Unlike snipe, lapwing, curlew and redshank did occur in improved fields, albeit at reduced densities. In the case of the lapwing, the relatively low densities on the improved land were probably due partially to low breeding success (Baines, 1989). Lapwings were more likely to hatch eggs and to fledge chicks on unimproved grasslands than improved grasslands. Annual production of young per breeding pair on unimproved grasslands was sufficient to replace annual losses but that on improved grasslands was not. Hatching and fledging success of redshank were slightly higher on unimproved than on improved grassland but the difference was not significant. It was not determined whether or not the annual fledging success per pair was sufficient to balance annual losses. Baines (1990b) subsequently demonstrated that the reduced breeding success by lapwings on improved grasslands on the hill-edge was due mainly to higher predation levels. Destruction of clutches during agricultural activities compounded the losses due to predation: the frequency was four times higher on improved than on unimproved grassland. The availability of invertebrates taken by lapwings was lower in improved than in unimproved fields but this had only a minor effect on breeding success. An experiment with artificial nests containing gull eggs confirmed that the rate of egg loss due to predation was much higher on improved than unimproved fields. Baines suggested that nests with eggs on improved grasslands were more visible to predators than those on unimproved swards because improved swards were relatively uniform and lacked the heterogeneity of sward structure and surface topography that were characteristic of unimproved fields.
A comparative approach was also used to assess the impact of moorland and hill-edge management on black grouse (Baines, 1996). Black grouse densities and breeding success were compared on five blocks of moors in northern England and Scotland. Each block contained four moors that differed in the intensity with which they were grazed (high or low) and whether or not predator control was undertaken. Heavily grazed moors contained shorter vegetation and fewer invertebrates than lightly grazed moors. The highest densities of black grouse occurred on lightly grazed moors where breeding success was also better. There was no association between density, breeding success and the presence of gamekeepers. Baines suggested that grazing management was the key to maintaining good ground cover with high densities of invertebrates for black grouse. The corollary of these findings is that increases in grazing pressure would lead to population declines whereas a relaxation of grazing pressure would result in a local recovery. The latter prediction was upheld by a replicated field experiment (Baines et al., 2002).
Comparison of trends in bird numbers and changes in agricultural land use.
Swindells (1997) compared counts of breeding birds on hill-edge grasslands in Upper Nidderdale before and after agricultural intensification. Snipe, redshank, skylark and yellow wagtail had disappeared between 1963-69 and 1996 while numbers of lapwing and meadow pipit had been reduced to very low levels. These declines were attributed to the agricultural changes that had occurred during the intervening period and those involving wader species were consistent with the prediction of Baines (1988). Rough grazing had been replaced with improved grassland that supported sheep at high
156 stocking densities. Meadows had been reseeded, or treated with herbicide to remove broad-leaved weeds, and nitrogen fertiliser had been applied to increase grass yield. Some meadows were also chain harrowed which may have increased the risk of nest destruction. The evidence was mainly circumstantial because no formal controls were included in the study, although it was ascertained that the loss of skylarks was restricted to the enclosed grasslands because skylarks were still breeding on moorland nearby.
Fuller et al. (2002) showed that the timing of the population declines on the two CBC sites in Rossendale and at Sutton-in-Craven differed between species and sites, suggesting that site-specific factors were operating. Unlike Swindells, Fuller et al. did not find a simple association between habitat changes on each farm and the patterns of decline. For example, numbers of lapwing and snipe increased at Rossendale site in the early years of the census period, despite losses of rough grazing, which runs counter to the prediction from other studies (e.g. Baines, 1988). However, the increase in the number of lapwings at Rossendale during a period of agricultural improvement may have been part of a long-term recovery from the severe losses that occurred during the 1962-63 winter. The subsequent reduction in lapwing numbers coincided with the decline in dairy farming. The birds preferred to nest on dairy pastures possibly because the late turnout dates minimised the risk of nest trampling and because farmyard manure applications may have enhanced the abundance of soil invertebrate prey for the birds. Cattle grazing also produced heterogeneous swards with good camouflage effects (c.f. Baines, 1990b) whereas intensive sheep grazing produced short uniform swards. Lapwings deserted the Rossendale study area after the last dairy enterprise closed in 1988. In contrast, the population declines at the Sutton site were not associated with any obvious change in agricultural land use. In the case of one species, the twite, the declines were synchronous between sites and it was suggested that they were probably due to a factor operating away from the farms.
The population declines recorded from the North Staffordshire Moors between 1985 and 1996 coincided with changes in agricultural management, including conversion of rough grazing to improved grassland, increases in silage production, drainage, intensification of grassland management e.g. topping of rushes (Juncus spp.) and increases in stocking densities both on hill-edge grasslands and the unenclosed moorland above (Brindley et al.,1992; McKnight et al.,1996). It was suggested that the losses of breeding waders were possibly due inter alia to a deterioration in the suitability of the habitat through changes in sward structure from heterogeneous to uniform swards, drainage and rush topping and to an increase in the risk of nest trampling following increases in the densities of livestock run on the hill-ground However, it was not possible to differentiate the respective effects of the various components of agricultural improvement. Moreover, as McKnight et al. observed, other factors may have also contributed to the declines, including increases in disturbance from recreational activities.
The studies by Swindells and Fuller et al. addressed the effects of agricultural improvement on hill-edge habitats that had already been altered either by grazing and/or enclosure. Jenkins & Watson (2001), however, investigated the long-term effects on bird numbers of the creation of hill-edge habitats by the conversion of dwarf shrub heath to grassland. They monitored changes in bird numbers between 1957 and 1961 and, again, between 1988 and 1998 in a study area in Glen Esk, in the
157 Eastern Highlands of Scotland. Numbers of breeding oystercatcher, lapwing and curlew increased on areas where dwarf shrub heath had been changed to grassland but not on an adjacent area where dwarf shrub cover was still extensive. There were also some losses. Densities of black and red grouse were high in one area of dwarf shrub heath prior to 1970 but both species had disappeared by the 1990s after the ericaceous vegetation had been converted to short grassland by heavy grazing. However, both species were still present on an adjacent area where grazing had been lighter.
Components of agricultural improvement and their effects
Agricultural improvement of hill-edge habitats entails the use of some or all of the following practices: drainage, reseeding, application of fertilisers and pesticides, and increases in stocking, especially with sheep. Reference has already been made to the combined effects of improvement on a number of components of a hill-edge grassland ecosystem in the northern Pennines that were identified by Baines (1988b). However, the effects of individual agricultural practices on hill-edge bird populations have, generally, not been identified partly because the agricultural practices have been carried out in combination.
Drainage
Several workers have suggested that drainage of grasslands on the hill-edge has resulted in the decline in the local densities of breeding waders (e.g. Bain, 1987; Ratcliffe, 1990). The best evidence for the effects of drainage comes from the comparative study by Baines (1988b) of improved and unimproved grasslands on the hill-edge in the northern Pennines. Snipe disappeared from improved grasslands that had been drained but not from unimproved grasslands that remained relatively wet. He suggested that drier soils may become too hard to probe and the loss of Juncus that follows drainage may remove nesting cover. Baines also showed that drainage reduced the numbers of other wader species, such redshank and curlew, but it did not result in complete desertion, which suggests that factors other than a high water table were important. In the case of redshank, adults may have been able to move their young from fields containing their nests to wetter areas nearby.
Reseeding
Reseeded grasslands tend to have a more uniform sward structure and surface topography than unimproved grasslands. This may lead to increased predation rates on the eggs of ground-nesting species, such as the lapwing, which rely upon complex sward structure and surface topography to camouflage their nests (e.g. Baines, 1990b).
Fertilisers
It has been suggested that the improved fertility of grasslands resulting from the application of fertilisers may lead to greater invertebrate abundance and benefit some bird species (Hudson, 1988). For example, greater numbers of starlings and crows are supported by improved than unimproved grasslands in late summer (Kahrom & Edington, 1983). In some instances, the enhanced growth due to fertiliser application may result in changes in sward structure that are deleterious to ground-nesting species, such as the lapwing (e.g. Baines, 1990b).
158 Pesticides
Infestations of tipulids are sometimes a problem following reseeding of moorland to grass and may be controlled by insecticides (e.g. Rushton et al., 1989). The effects of this practice on birds are unknown but may be deleterious (Bibby, 1988).
Changes in stocking rates following improvement
Large increases in the numbers of sheep occurred between the 1970s and late 1980s throughout the uplands of England and Wales. This trend was reversed in the 1990s’ but, by the mid-1990s, sheep numbers were still much higher than they had been in the 1970s (Fuller & Gough, 1999). The biggest increases in absolute numbers between 1950 and 1990 occurred in Wales. Fuller & Gough suggested that increases in sheep numbers may lead to changes in bird populations of grasslands by resulting in either the loss, or creation of, preferred vegetation types by altering the height, structure and species composition of ground vegetation; alteration of food supplies, and alteration of predation pressure. In practice, however, it is often difficult to isolate the consequences of increased grazing pressure from the agricultural improvements that facilitated higher stocking densities.
The severe declines in the numbers of ground-nesting birds in the Welsh uplands, have been highlighted by Shrubb et al. (1997), and an increase in grazing pressure by sheep was strongly implicated (Fuller & Gough, 1999). Intensive grazing by sheep on moorland tends to lead to a reduction in vegetation height and deterioration of heather cover and an increase in grass cover, often resulting in mosaic of dwarf shrub and grass moor. The effects of this change of the composition of moorland bird species assemblages are probably mixed. Pearce-Higgins & Grant (2001) suggested that red grouse and stonechat were most likely to decline as a result of high levels of grazing whereas declines in the moorland populations of snipe curlew and golden plover were probably not due to habitat changes resulting from increases in grazing pressure. Pearce-Higgins & Grant noted that golden plovers densities were often highest on heavily grazed moorland with an open vegetation structure, short vegetation height and chronically grazed heather. Skylarks may also have benefited from the fragmentation of continuous moorland into mosaics of dwarf shrub heath and grass (Pearce-Higgins & Grant, 2002).
Summary
x Spatial comparisons of improved and unimproved grassland on the hill-edge in the northern Pennines have shown that population densities of breeding waders tend to be lower on the improved land. This was due to elimination of habitat features that attract species to settle, as in the case of snipe, or to reduced breeding success on improved land, as in the case of lapwing. x The prediction that wader populations should decline when hill-edge habitats are improved agriculturally was supported by some comparisons time-series of counts and concomitant habitat changes but not others. x A spatial comparison of black grouse densities and breeding success on intensively and lightly grazed moors showed that both measures were higher on lightly grazed sites and that neither measure was related to game keeping.
159 x The prediction that black grouse densities and breeding success should increase following a relaxation of grazing was supported by a replicated field experiment. x Time-series of counts of breeding birds on several sites showed that several passerine species declined markedly from the 1960s onwards. Some declines coincided with agricultural changes but others did not. x The simultaneous decline of twite at two sites in the Pennines was attributed to a factor operating away from the breeding sites. x As agricultural improvement involves a combination of changes, the effects of individual factors on bird populations were difficult to distinguish.
Afforestation
Extent and nature of habitat change
Afforestation with conifers has effected major and long-lasting changes to upland habitats in England and Wales. Land allocated for planting is rapidly modified by ploughing, application of fertilisers (usually phosphates) and, sometimes, drainage (Avery & Leslie, 1990). Once land has been afforested, it has tended to remain under forestry management. The statistics compiled by Parry et al. (1982a…e; 1984) indicated that, within the upland National Parks, the area of land under trees that was allowed to revert to rough pasture was very small indeed compared to the areas planted. By 1990, more than 1 million ha of conifer forest had been planted in the uplands of Britain (Ratcliffe, 1990). A proportion of these plantings will have been on hill-edge habitats. Thompson et al. (1988) estimated that 31%, by area, of upland grassland in the less Favoured Areas of England and Wales had been lost between 1949 and 1981. Approximately two thirds of the losses (67%), by area, were due to afforestation.
Bird species succession following planting
After planting, there is a progressive disappearance of open country species, the temporary colonisation of young plantations by hen harriers, short-eared owls, black grouse and others, prior to the closure of the forest canopy, and the arrival of scrub and woodland species (Ratcliffe, 1990). The succession of woodland bird species in developing conifer plantations has been described in detail by Bibby et al. (1985) and Sykes et al. (1989). Sykes et al. monitored changes in bird numbers following the establishment of a conifer plantation on sheepwalk in Cumbria. It is the most detailed record of the succession of open country species following afforestation but no data were collected prior to planting. Redshank, snipe, lapwing and red grouse remained in small numbers (<5 pairs) for four years after planting and then disappeared. Curlew, short-eared owl and black grouse remained for six, eight and nine years respectively. Skylark numbers gradually declined and the birds disappeared after nine years. Meadow pipit numbers declined gradually but were still numerous 13 years after planting. Finally, some open-country species may have benefited from planting. Numbers of whinchats increased to a peak seven years after planting before declining. Some hill-edge species, such as black grouse, short-eared owl and curlew, may reappear temporarily when forestry blocks are clear-felled prior to replanting (Ratcliffe, 1990). In the North York Moors, nightjars, which formerly occurred on
160 wooded hill-edge habitats, returned to clear-felled areas in Cropton Forest (Avery & Leslie, 1990).
The number of displaced breeding pairs of open country species may be very significant. Ratcliffe (1990) estimated of the losses of territories of the following species as result of the afforestation of 58,000 ha of upland in the Southern Cheviots: 1750 pairs of curlew, 1200 pairs of golden plover, 200 pairs of dunlin, 11,600 pairs of red grouse, and 25 pairs of merlin were estimated to have been lost as a result of the conversion of moorland and hill-edge habitats.
The consequences for open country species are not entirely negative, however, because the merlin has exploited the development of mature conifer plantations in the uplands. In the Cambrian Mountains ESA, c. 90% of breeding pairs nested in the margins of mature forestry blocks (Parr, 1991).
Effects on birds on land adjacent to plantations
The fate of the open country species that are displaced by planting is not known but some may attempt to move to unplanted areas nearby where they may compete with birds that are already there. Thompson et al. (1988) presented a number of possible scenarios: the least severe was that breeding success per pair would decrease slightly because of competition and the occupation of poorer quality habitats. The worst-case scenario was that the arrival of displaced birds raised local densities on unplanted areas to such an extent that increased levels of competition and predation would result in population declines.
In addition to the displacement of birds from the planted areas, afforestion may have wider effects on breeding birds, particularly birds of prey and carrion eaters. Four case studies in SW Scotland and central Wales assessed the effects of afforestation on golden eagle, red kite, buzzard and raven, all of which hunt for food on the hill-edge for at least part of each year. The effects appeared to depend largely upon the extent and pattern of planting. Marquiss et al. (1985) showed that the breeding performance of golden eagles nesting in SW Scotland was related to the availability of low altitude habitat, including hill-edge habitats and demonstrated that declines in breeding success occurred when this habitat was eliminated by extensive planting. A second case study showed that the number of ravens breeding in southern Scotland and northern England declined significantly between the 1960s and 1974-5 and demonstrated that the desertion of nest sites was associated primarily, but not exclusively, with elimination of sheepwalk from the surrounding territories by afforestation (Marquiss, Newton & Ratcliffe, 1978). In central Wales, however, the effects of afforestation on red kites (Newton et al., 1996), buzzards and ravens (Newton et al., 1981) were negligible, up until the 1980s, possibly because the planting was in relatively small blocks and not in very extensive tracts, as in SW Scotland. However, further afforestation was predicted to have an adverse effect on ravens and a beneficial effect on buzzards. Thompson et al. (1988) give additional examples from Scotland of local population declines in golden eagle and buzzard through afforestation.
There have also been concerns about possible edge effects of new plantations on ground-nesting birds occupying adjacent moorland and rough grazings (e.g. Stroud et
161 al. 1987). These effects were thought to include elevated predation risk from tree- nesting predators, such as crows that had previously either been absent or present at low density, leading to reductions in breeding success and nesting densities adjacent to plantations. Avery (1989) modelled bird-habitat relationships from three partially afforested areas (two in Caithness, one in the Pennines) to investigate whether or not the distributions of two hill-edge species (curlew & golden plover) and two moorland species (dunlin & red grouse) showed edge effects near plantations. However, no effect of the proximity of plantations on the breeding densities was detected.
Summary
x Afforestation with non-native conifers has effected extensive and long-lasting habitat changes on the hill-edge. x Most bird species of open country desert plantations at an early stage. x Black grouse short-eared owl, hen harrier and whinchat exploit young plantations but desert them when the woodland canopy closes. x Some species, including curlew and black grouse, reappear temporarily in clear felled areas. x The effects of afforestation may extend beyond the boundaries of the planted areas by reducing the food supply of birds of prey and carrion eaters that hunt for food on the hill-edge, thereby resulting in population declines. x It has been hypothesised that the displacement of birds from afforested areas may lead to competition with other individuals of the same species that occupy unplanted areas, resulting in reduced breeding success or, in the worst cases, population declines.
Discussion
The foregoing sections have identified some of the mechanisms by which afforestation and/or agricultural land improvement can reduce or eliminate local populations of breeding birds on the hill-edge. What is less clear is the degree to which the widespread declines of hill-edge species are due to land use change or whether other factors have been involved. Spatial comparisons of bird densities and, in some cases, breeding productivity, on improved and unimproved grassland or moorland indicated how populations of breeding waders and black grouse might change following agricultural improvement or changes in grazing pressure. However, the predictions of the spatial comparisons were not always upheld when time-series of bird counts were compared with concomitant changes in agricultural practice or grazing patterns. In some cases, this was because population declines occurred when there were no changes in farming practices (Robson & Williamson, 1972; Fuller et al., 2002), whereas, in others, the population trends were the reverse of what had been predicted (Fuller et al., 2002).
The lack of agreement between the spatial and time-series analyses may be because the findings of the few spatial comparisons that have been carried out were not representative of the full range of conditions on the hill-edge. However, it is more likely that changes in habitat condition (physical structure and food supplies) have only partially determined population trends of hill-edge birds. It is probable that quality of habitat of the hill-edge, for a given species, varies between areas, so that in areas of poor habitat quality, it is possible that population declines were driven by
162 meta-population processes. An increase in the risk of predation, particularly of ground-nesting species, appears to have been important in some areas, such as the uplands of Wales (Shrubb et al., 1997) but not in all areas or for all species (e.g. Baines, 1996). Finally, a proportion of the population declines recorded from hill- edge habitats may be determined by factors operating away from the hill-edge, as in the case of twite (Fuller et al., 2002). Consequently, it cannot be safely assumed that habitat management on a local scale will invariably be sufficient to effect local population recoveries. The implications for habitat management on the hill-edge, including the formulation of conservation management prescriptions for agri- environment schemes, are considered at greater length in the final chapter of the report.
Is the hill-edge nationally important for the conservation of upland birds?
The priorities for the conservation of hill-edge bird species are determined primarily the statutory obligations stemming from the EU Birds Directive, particularly Annex I, and by the inclusion of species in the List of Bird Species of Conservation Concern (Gregory et al., 2002).
Six hill-edge species are covered by Annex I of the EU Birds Directive (Table 7.13). These include one species, the red kite, that occurs principally on the hill-edge in Wales, and four of the seven species that nest on moorland, but which use and, perhaps rely, upon hill-edge habitats for food (Table 7.7). The Special Protection Areas that have been designated to protect these species are listed in Table (7.14).
Twelve bird species, including five of the six EU Directive species, have been placed on the List of Bird Species of Conservation Concern either on the Red or Amber lists. Most of the species on the Red list have been included because they have unfavourable population status in the United Kingdom (Gregory et al., 2002). However, the population status of the twite is relatively stable and it is included on the Red List because the population in the UK is of international importance (Batten et al., 1990). This species has a disjunct breeding range across Europe and Asia. The populations in Western Europe are geographically isolated and largely confined to Scandinavia and the British Isles (Bub et al., 1997). The twite that breed in the British Isles comprise a distinct race Acanthis flavirostris pipilans (Brown, Crick & Stillman, 1995).
163 Table 7.13. Hill-edge bird species included in the EU Birds Directive and/or on the List of Species of Conservation Concern (Red & Amber Lists). Bird Species of Conservation EU Birds Directive(2) Concern (1) Species Red list Amber list Annex I Red Kite xx Golden Eagle xx Hen Harrier xx Merlin xx Black Grouse x Grey Partridge x Golden Plover x Snipe x Curlew x Skylark x Ring Ouzel x Chough xx Twite x Data sources: (1) Gregory, R.D., Wilkinson, N.I., Noble, D.G., Robinson, J.A., Brown, A.F., Hughes, J., Procter, D., Gibbons, D.W. & Galbraith, C.A. (2002). The population status of birds in the United Kingdom, Channel Islands and Isle of Man. British Birds, 95, 410-448. (2) Tucker, G.M. & Heath, M.F. (1994). Birds of Europe: their conservation status. Birdlife International, Cambridge.
Both hill-edge specialists, black grouse and red kite, and six of the seven species that nest on moorland but use, or rely upon, hill-edge habitats for feeding are included on either the Red or Amber Lists. The remaining species on the List of Species of Conservation Concern, grey partridge, snipe and skylark, are primarily birds of lowland habitats where their numbers and/or breeding ranges have declined. The hill- edge populations of these species may be of national importance. Strategies for stabilising and recovering the populations of the Species of Conservation Concern have been set out in Biodiversity Action Plans at either national and/or local levels (Table 7.15). The preparation of Local Biodiversity Action Plans for some upland areas is not yet complete.
The third criterion for the assessment of conservation priorities involves the identification of areas that contain nationally or internationally important concentrations of particular species. This approach has been applied primarily to waterfowl and is not confined to EU Directive species or to those of Conservation Concern. Breeding waders fall into this category. The 1% population thresholds of UK and European populations have been used as a guide to the identification of sites of nationally and international importance respectively (e.g. Musgrove et al., 2001).
Enclosed farmland on the hill-edge, as in Baldersdale and Lunedale, Upper Teesdale and Eden Valley, has been shown to support relatively high densities of lapwing, oystercatcher, snipe, curlew and redshank (Table 7.16). When these densities are converted into population estimates for designated areas, particularly the Yorkshire Dales National Park and the Forest of Bowland Area of Outstanding Natural Beauty, the concentrations of lapwing, oystercatcher, snipe and curlew in exceed the 1% level for UK breeding populations (Table 7.17).
164 Table 7.14. Special Protection Areas (SPAs) in England and Wales identified to safeguard breeding populations of hill-edge bird species addressed by Articles 4 .1 & 4.2 and Annex I of the EU Birds Directive (details from www.jncc.gov.uk/UKSPA/sites). Special Protection Areas Bird species North Pennine North York Bowland Fells South Pennines Migneint- Berwyn Elenydd- Moors Moors UK9005151 UK9007021 Dduallt UK9013111 Mallaen UK9006272 UK9006161 UK9013131 UK9014111 Red Kite x Hen Harrier xxxx Merlin xxxxxxx Golden Plover xx x Curlew x Chough
Table 7.15. UK (UKBAP) and local biodiversity action plans (LBAP) for hill-edge bird species in principal upland areas of England and Wales (National Parks). LBAPs Species UK BAPs Northum- Lake Yorkshire North York Peak Snowdonia Brecon Dartmoor Exmoor berland NP District Dales NP Moors NP District NP NP Beacons NP NP NP NP Red Kite x Hen Harrier xx x Merlin Black Grouse x Grey Partridge x Golden Plover Snipe x Curlew x Skylark x Ring Ouzel Chough Twite x Key to symbols: x - BAP (LBAP) completed ; - BAP (LBAP) in preparation.
165 Table 7.16. Estimates of densities (pr km-2) of breeding waders in northern England from surveys carried out between 1990 and 1993. (Adapted from Murray et al., 1993). Survey (area, year, source) Area covered Lapwing Oystercatcher Snipe Curlew Redshank km2 Baldersdale/Lunedale 1993 (1) 34 34.4 2.9 13.7 9.4 5.5 Upper Teesdale 1990 (2) 16 46.4 0.6 5.9 3.4 4.7 Eden valley 1992 (3) 14 11.3 7.4 2.1 8.6 4.8 Forest of Bowland (key sites) 8 19.6 0.6 3.5 2.1 2.5 1993 (4) Forest of Bowland (random) 23 8.4 2.1 1.2 3.0 0.9 1993 (4) Pennine Dales 1993 (6) 29 8.5 1.1 1.3 3.0 0.7 North Staffordshire Moors 58 2.1 0.0 5.4 4.6 0.0 1992 (5) Random squares in northern 99 3.0 0.5 0.1 1.7 0.2 England 1993 (6) Notes: Data sources: 1 = Shepherd (1993), 2 = Barrett & Findlay (1990); 3= Day (1992); 4 = Campell et al. (1994); 5 = Brindley et al. (1992). 6 = Murray (1993).
Table 7.17. Population estimates (breeding pairs) for waders breeding on enclosed land in the Yorkshire Dales National Park (YDNP) in 2000 (after Shepherd, 2001), and in the Forest of Bowland Area of Outstanding Natural Beauty (AONB) in 1998 (Babbs, 1998) in comparison with UK population estimates and 1% thresholds. Current population Oystercatcher Lapwing Snipe Curlew Redshank estimates UK 34,000-44,000 128,811 58,930 35,119-40,119 30,793-33,793 1% UK threshold 440 1,299 590 402 338 Enclosed upland in 460-781 889-1591 245-745 1106-1527 83-301 the YDNP Bowland AONB 957 2470 184 2843 261 Notes: breeding populations exceeding the 1% threshold are shown in bold.
This review has identified that the hill-edge bird communities in England and Wales comprise three main components: (i) those species that occur primarily on the hill-edge, (ii) species that nest on moorland but which use, and perhaps rely upon, hill-edge habitats for food, and (iii) species that occur in the uplands and lowlands. Both of the hill-edge specialists, red kite and black grouse, and all seven moorland species that use the hill-edge as a feeding habitat ((golden eagle, hen harrier, merlin, golden plover, curlew, ring ouzel, and twite), are of national or international conservation importance. Grey partridge, skylark and snipe occur widely but their population status is unfavourable and they are included on either the Red or Amber Lists of Species of Conservation Concern. The populations of the hill-edge may be nationally important but their demographic status (source or sink) is not known.
Summary
x The hill-edge supports 13 species that are of national or international conservation importance, which are covered by the EU Birds Directive and/or are included in the Red and Amber Lists of Species of Conservation Concern. x The lists include the two species that occur primarily in the hill-edge habitats (red kite and black grouse) and all seven moorland species that use, and perhaps rely upon, hill-edge habitats for food (golden eagle, hen harrier, merlin, golden plover, curlew, ring ouzel, and twite). x The remaining Species of Conservation Concern (grey partridge, snipe and skylark) occur primarily in the lowlands where their numbers have declined. The hill-edge populations may be nationally important.
166 x Enclosed farmland on the hill-edge in the Yorkshire Dales National Park and Forest of Bowland Area of Outstanding Natural Beauty supports nationally important concentrations of several breeding wader species.
167 MAMMALS
Summary
x No species of mammal is dependent on hill-edge habitats in England and Wales although most species may occur in these areas to a greater or lesser degree. Nonetheless, hill-edge habitats are probably significant for two UK BAP species: the barbastelle bat Barbastella barbastellus and water vole Arvicola terrestris. x Marginal woodlands and scrub bordering moorland in parts of SW England appear to be important feeding habitats for barbastelle bats. x Rivers and streams in the uplands, including the hill-edge, in Scotland and probably northern England, support relict populations of water voles which are of increasing significance for the survival of the species, given the population declines in the lowlands.
Introduction
The UK has a total of 56 species of wild or feral terrestrial mammal, 53 of which occur in England or Wales. The majority of these species are primarily associated with lowland habitats and only a small number (e.g. red deer Cervus elaphus and mountain hare Lepus timidus) of species are primarily associated with upland habitats in England and Wales. The majority of species probably occur in hill-edge areas although documentation of this is scarce. There is little published literature on mammals in the uplands in general but, as with some species of predominantly lowland birds, the hill-edge areas may have increased in national importance for some scarce species due to declines in the main populations in the lowlands. There has been some suggestion that this is the case for water voles Arvicola terrestris. Numbers of water voles underwent a catastrophic decline during the last decade of the 20th Century, as a result of which the species is the subject of a UK Biodiversity Action Plan (Anon., 1995g). This decline is mainly attributed to mink Mustela vison predation. Headwaters of streams in the Scottish Highlands have recently been identified as having important relict populations probably due to lower predation levels by mink (Raynor, 2002). Similar suggestions were made for parts of the northern Pennines during the consultation phase of this project (GCT, personal communication). More substantial data need to be collected to confirm these suggestions, as these refuge areas may be vital for saving this critically endangered species.
Small mammals
Many other species of small mammals also occur in hill-edge farmland (although several such as harvest mouse Micromys minutus and yellow-necked mouse Apodemus flavicollis probably do not) but probably in reduced numbers compared to suitable habitat in the lowlands. The main exceptions to this trend of decreased abundance in the uplands are pygmy shrews Sorex minutus and field voles Microtus agrestis both of which reach high population densities in the uplands. In the case of pygmy shrews, which in the lowlands are greatly outnumbered by common shrews Sorex araneus, the situation is reversed in upland areas. Whiteley & Yalden (1976) carried out a long-term survey of small mammals in the Peak District using a variety
168 of techniques. They concluded that common shrews were numerous up to the moorland edge occurring in habitats including bracken covered slopes, grassland, woodland and scrub. They were only scarce in the extensive heather moorlands where earthworms are uncommon. In contrast the pygmy shrew was relatively more abundant in the moorland, possibly due to their lesser reliance on earthworms (Butterfield et al., 1981). Bank voles Clethrionomys glareolus also occurred in the Peak District but in far lower abundance than in most lowland areas, this may have been due to the relative scarcity of scrub and hedgerows on which bank voles rely. Field voles were relatively common, but as they need tussocky grassland high sheep densities serve to reduce habitat suitability. Wood mice Apodemus sylvaticus were also widespread and abundant in the area. Whitely & Yalden (1976) have implicated the increase in sheep numbers (trebling between 1930 and 1968) in the relative scarcity of bank voles overall and for the scarcity of field voles on many of the heavily grazed areas. They also note the potential detrimental effects of this on owls.
Bats
Bats are one of the largest groups in the British fauna comprising c. 30% of total species. Virtually all of Britain’s bat species (n = 16) are primarily associated with lowland habitats and extensive detector transects carried out by Walsh and Harris (1996) indicate that there are low bat abundances in marginal and upland habitats. However, the Barbastelle Barbastella barbastellus, one of Western Europe’s rarest bats and a UK BAP species (English Nature, 1998), appears to be more closely associated with hill-edge habitats. This association appears to be particularly so for marginal woodlands in steep valleys and some recent radio-tracking data from Somerset (Exmoor) indicated that scrub dominated coombs bordering on moorland were key foraging habitats. The mosaic areas of gorse, bracken and woodland close to moorland were described as excellent for several bat species in Exmoor (G. Billington, conference paper). Daubenton’s bat Myotis daubentoni is also known to occur far up river valleys in many areas e.g. the Yorkshire Dales (J. Altringham, pers. comm.) with males foraging up higher in the valleys than females. Many of the commoner bat species (e.g. noctule Nyctalus noctula, whiskered Myotis mystacinus, Brandt’s Myotis brandtii, brown long-eared Plecotus auritus etc.) probably occur in hill-edge areas but data quantifying this are scarce. During the consultation phase of this project CCW suggested that noctule and natterer’s Myotis nattereri may be more closely associated with ffridd habitats than other Welsh bat species but this would need further investigation. There are several other species that are unlikely to occur in hill-edge areas viz. Bechstein’s Myotis bechsteinii (closely linked to ancient semi- natural woodland in the south of England), grey long-eared Plecotus austriacus (confined to the English south coast) and Serotine Eptesicus serotinus (main distribution in the south east of England).
Mustelids
Most of the mustelids probably occur in hill-edge areas, certainly stoats occur up to high altitudes (Harris et al., 1995). There has also been the suggestion that Pine Martens Martes martes, a very rare species in England and Wales (numbering less than 200 individuals), are associated with ffridd habitats in Wales (CCW, personal communication) and they are often associated with marginal rocky and wooded areas in Scotland and Ireland. This would need confirmation by survey work. Polecats
169 Mustela putorius, whose main distribution is in Wales, the Welsh Borders and now much of the Midlands, are predominantly a lowland species as are weasels Mustela nivalis and badgers Meles meles. Otters Lutra lutra, however, probably occur in greater numbers in marginal upland areas than in the lowlands, although their lowland populations are now rapidly expanding.
Deer
Of the British deer species, only red deer are closely associated with upland habitats, although they will occur at all altitudes in the UK. The main English population occurs in the south west where numbers are increasing. They undoubtedly occur in hill-edge habitats but the importance of these habitats to the population is unknown. Of the other deer species, it is likely that roe Capreolus capreolus will occur in hill- edge areas but fallow Dama dama, muntjac Muntiacus reevesii and Chinese water deer Hydropotes inermis are all primarily associated with lowland habitats.
170 RESUME AND IDENTIFICATION OF GAPS IN CURRENT KNOWLEDGE AND FUTURE RESEARCH NEEDS
Resume
A model based on CEH land classes, and excluding altitudinal criteria and linear features, such as the moorland wall, indicates that hill-edge vegetation is extensive in the uplands of England and Wales. The estimates of the area of hill-edge vary considerably between 12 upland regions of England and Wales, from 5,812 ha in the Shropshire Hill ESA to 148,425 ha in the North Pennine Dales. However, the area of hill-edge did not vary in proportion to the area of core moorland in each region. Expressed as a percentage of the core moorland area, the area of hill-edge varied from 31% in the North York Moors to 203% in the Lake District. The median percentage was 87%. The percentage for the Lake District was very much larger than the other values in the sample. It is not clear whether this estimate was too high because the model settings were not appropriate for the local conditions, or whether the fit of the model was adequate and it has highlighted a characteristic of the Lake District that had not been recognised hitherto. Recent distribution maps of upland birds in the Lake District and northern Pennines (Brown, Stillman & Gibbons, 1995) lend support to the latter possibility because the distribution of tetrads occupied by moorland species matches our estimates of the extent and location of moorland fairly closely.
The dynamic nature of the hill-edge has been highlighted and it has been shown that the current landscape has been shaped by repeated episodes of agricultural improvement and reversion. Within regions, reclamation and reversion have been patchy and the timing and duration of these changes in land use have varied between locations. The scale and timing of reclamation and reversion has also varied regionally. These differences have resulted in mosaics of habitats on the hill-edge at several spatial scales. These mosaics appear to be important for some invertebrate and bird species.
Concerns about the rate and scale of recent agricultural improvement on the hill-edge in England and Wales have been only partially corroborated by the geographical surveys of the upland National Parks and of central Wales carried out by Birmingham University and Silsoe College. These surveys imply that, in the 1970s and 1980s, improvement was rapid and extensive in some areas, such as central Wales and the Yorkshire Dales, Lake District and Snowdonia National Parks, but that it was much less widespread in other areas. The situation in the 1990s relative to previous years is unclear but, ultimately, monitoring data from those Environmentally Sensitive Areas that lie within National Parks will indicate whether the rate of agricultural improvement has been halted or even reversed. Afforestation eliminates the vegetation and habitat mosaics of the hill-edge. It has been extensive in some National Parks and elsewhere, as in central Wales and the Scottish Borders.
The current state of knowledge about the plant and animal communities, and their dynamics, varies considerably between taxa and is not currently sufficient to formulate detailed targets for conservation management for more than a few high profile species, such as the black grouse. Though the level of information about the vegetation of the hill-edge is adequate at the Phase 1 level, more detailed information about communities is frequently lacking mainly because much greater attention has
171 been given to other areas, such as dwarf shrub heaths on the moorland above, or hay meadows on improved land below. Our knowledge of the macro-invertebrates in hill- edge habitats is largely dependent on a small number of studies, most of which were carried out in the northern Pennines, while almost nothing is known about amphibians, reptiles and mammals on the hill-edge. Much more is known about the birds of hill-edge habitats, and survey data are just about sufficient to characterise the species assemblages and their geographical variation.
The effects of agricultural improvement on plant and animal communities have been largely negative but appear to be at least partially reversible over the medium-term (3 years) in the case of plant species assemblages on hill-edge grasslands (e.g. Hayes et al., 2000a). Over-grazing is a key issue, especially in the case of the conservation of scrub and semi-natural woodland. The effects of agricultural improvement on animal populations are less clear and may be longer lasting. More is known about the effects on birds than any other animal group. Improvement tends to reduce invertebrate food supplies, alter the physical structure of the hill-edge habitats that attract particular species to settle and reduce breeding success by increasing the risk of nest trampling and predation. These changes have resulted in local decreases in density, particularly of breeding waders, but many population declines have not been synchronised with agricultural changes on hill-edge farms, which implies that other factors may have been involved. In general, the causes of the widespread declines of many hill-edge species are not understood sufficiently to formulate remedial measures. Loss of habitat mosaics on the hill-edge may also have been critical in some cases, particularly the black grouse.
The Environmentally Sensitive Area and Countryside Stewardship Schemes provide an incentive for managing the hill-edge for environmental objectives, including biodiversity. They include conservation management prescriptions that are targeted at hill-edge habitats, especially enclosed pasture, hay meadows and remnant woodland. However, the prescriptions are not designed to deliberately create or maintain the mosaic of habitats that is such a characteristic of the hill-edge. Rotational grazing management may be necessary but the levels of grazing required and the scale of the mosaics are not yet sufficiently understood and should be investigated by replicated experiment (c.f. Baines et al., 2002).
Requirements for further work on the hill-edge
The broad objective is to develop agri-environment measures that are suitable for application in a future hill-edge scheme. The objectives for such a scheme should be the integration of sustainable agricultural practices with enhanced biodiversity for the hill-edge.
There is a need to develop conservation management prescriptions which reduce grazing pressure on hill-edge habitats and which maintain, or promote the development of, habitat mosaics. This work should be set against a backdrop of declining agricultural incomes in upland areas, a move away from headage payments as the support mechanism for upland farming, and the possibility of agricultural dereliction in some areas. Hill-edge habitats and mosaics are the consequence of increasing and decreasing intensities of agricultural use through time. As such, they
172 are particularly sensitive to changing agricultural fortunes and this process should be managed to optimise the benefits for biodiversity and sustainability.
For the hill-edge itself, the underlying aim should be to manage vegetation succession. In many cases, this will incorporate a move away from the current high grazing pressure/year round grazing systems produced by the headage payment systems towards one characterised by lower density, seasonal grazing with a managed diversity of successional stages represented in an appropriate mosaic. The targeted creation of wet areas, scrub and woodland would also feature within a potential package of management prescriptions.
Issues raised by these considerations include:
x The effects of reducing a) stocking densities and b) winter grazing on succession. There is a need for manipulative field experiments or for building on ad hoc experiments elsewhere. Sustainable and economic options for indoor or away-wintering of stock need to be explored. x A more detailed examination of existing mosaics by region is required and which should determine appropriate mosaic scales and structures for selected species. x Common prescriptions are likely to involve identifying allotments for reduced grazing, including both reduced stocking densities and limited seasonal grazing. How can we best identify those allotments that would benefit the most? Can we predict how different grazed stands will respond? x How do we best enhance mosaics, including both the size and spatial spread of features? x Field experiments carried out by the Game Conservancy Trust (e.g. Baines et al., 2002) have shown that newly ungrazed grasslands are very valuable for a range of species but they become less diverse and valuable after 3-5 years. Further experimentation either on the GCT plots or elsewhere is necessary to examine the effects of reintroducing sustained levels of grazing. x Management methods need to be devised to avoid the encroachment of invasive ‘weed’ species (bracken, Molinia etc) but that also recognise the beneficial role of these species when in appropriate mosaics. Can we identify which areas are vulnerable to invasive plant species? The effects of removing grazing pressure on succession and communities. Regeneration of other species following control of invasives (bracken and allelopathy). x Hydrology of the hill-edge and the role of wet areas. The historic role of hill drainage in determining the hill-edge fauna and flora requires attention. The recreation of wet areas is likely to be of particular value to biodiversity and appropriate management prescriptions need to be developed. Their effects also need to be examined by manipulative experiment, with an emphasis on invertebrates. x Targeting of existing habitats for special treatment, e.g. fencing existing scrub and woodlands – effects on regeneration. The local and regionally appropriate opportunities for planting strategies, e.g. gill-side planting, need to be explored. x Limiting factors to the promotion of successional mosaics also need to be explored. For, instance, grazing by rabbits can have a major suppressive effect on vegetation in some areas. Similarly, dense swards of unpalatable grasses
173 can be slow to respond to reductions in grazing pressure. Methods of identifying and ameliorating these effects need to be explored. x Further species studies are required, particularly of species that are sensitive to habitat mosaics on the hill-edge, and of BAP species, such as the bird species identified previously, the barbastelle bat and high-brown fritillary.
Strategic Issues
This review has identified several issues that relate to conservation strategy as well as practical issues relating to the management of hill-edge habitats for conservation objectives.
The model of hill-edge habitats presented here is derived solely from CEH land classes and, thus defined, the hill-edge extends uphill onto unenclosed moorland. Habitat patches of dwarf shrub heath and grass are an integral feature of the hill-edge but their perceived conservation value appears to be contingent upon their location. On unenclosed moorland, such habitat mosaics are often regarded as evidence of habitat degradation in need of restoration yet in enclosures the same features comprise valuable habitat for breeding birds. This apparent conflict needs to be resolved, by zoning if necessary.
Bracken management is a key issue in the uplands and stands of bracken are an integral feature of the hill-edge. The perception of bracken as having no value to wildlife is questionable. Though bracken is a pest, mosaics of bracken and other vegetation appear to be an important habitat for some invertebrates, e.g. high brown fritillary Argynnis adippe and birds, e.g. whinchat, in some areas. These habitat associations, and the factors that determine them, need to be examined further to develop an appropriate local management strategies
Many of the species that breed in hill-edge habitats formerly occupied much larger ranges and a broader range of habitats. The presumption is that they have survived here because of the quality of the habitat is higher than in other but this may not be the case. The prime example is the Welsh population of the red kite, which is largely concentrated in the ffridd because of persecution and disturbance by humans but would breed in more biologically productive habitats if persecution and disturbance were relaxed (e.g. Newton et al., 1981). Several species, such as lapwing, snipe and whinchat, have retreated from lowland habitats to the hill-edge where they now occur in nationally important concentrations. However, it is not known whether these remnants are source populations, or sink populations maintained by immigration from elsewhere. Much more needs to be known about the demographic status of these hill- edge populations.
There is a need to determine the limiting effects of hill-edge grasslands on moorland bird species, particularly those that are covered by Article 4 (& Annex I) of the EU Birds Directive and which are covered by Special Protection Area designation, e.g. golden plover and merlin, and other Species of Conservation Concern, e.g. twite and ring ouzel. The hill-edge grasslands used as feeding habitats often lie outside the boundaries of SPAs and, therefore, receive no protection. Much more needs to be known about the potentially limiting effects of these grasslands on moorland breeding
174 populations, on the selection by the birds of these grasslands and agricultural management that determines the quality of the hill-edge grasslands as feeding habitats.
175 REFERENCES
The following list gives details of the primary literature sources consulted in this review. Not all references have cited in the main body of the report partly because only a small proportion of the references contain substantial descriptions to the hill-edge; the remainder only refer to the hill-edge incidentally. As a high proportion of the entries relates to material that is either unpublished and/or difficult to obtain, short summaries have been prepared for each entry to indicate their contents and their relevance to the hill-edge.
ADAS. (1988) Agriculture in Wales. Welsh Office Agriculture Department, UK. Basic facts and figures on agriculture in Wales.
ADAS. (1991) Environmental R&D at Pwllpeiran, ADAS, Pwllpeiran, UK. A list and brief summary of environmental R&D experiments at Pwllpeiran Experimental Husbandry Farm in April 1991.
ADAS. (1992) Environmental R & D at Pwllpeiran, April 1992. Unpublished ADAS report. Pwllpeiran, UK Review of conservation and environmental activities at Pwllpeiran 1955-1992, including vegetation surveys (pp. 3-4), wildlife monitoring (pp. 8-9), Pwllpeiran and the Cambrian mountains ESA (pp. 9-10), the Tynbryn project on Calluna and semi-natural rough grazing (pp. 12-18).
ADAS. (1996a) Environmental monitoring in the Pennine Dales ESA 1987-1995. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. Surveys have been carried out to monitor landscape by measuring changes in land cover and landscape elements such as field boundaries and barns. The ESA is dominated by grassland which has been enclosed for use as hay meadows and pastures. Their botanical diversity is the key reason for the area’s designation though they are an important habitat for ground-nesting birds and breeding waders. Over the monitoring period, most grassland communities were being maintained. There had been a slight deterioration in landscape features.
ADAS. (1996b) Botanical monitoring of grassland in the Pennine Dales ESA 1987-1995. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. The report outlines the results from the grassland monitoring programme. The ESA is dominated by grassland which has been enclosed for use as hay meadows and pastures. Samples were classified into vegetation types and changes related to ecological criteria affected by ESA prescriptions: grazing, nutrient status and poaching. Overall, there was an increase in species associated with low nutrient status. There was no significant changes associated with changes in grazing and poaching was a minor factor affecting species composition.
ADAS. (1996c) Landscape monitoring in the Pennine Dales ESA 1987-1995. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. Land cover in the core ESA was mapped in 1987 and the extension areas in 1992, and changes in land cover were identified in 1995. Very little change was identified, affecting only about 1% of the ESA area. The main change was the loss of neutral grassland to improved grassland. There was an overall decrease in the area of bracken but bracken encroachment occurred at the expense of neutral grassland.
ADAS. (1996d) Historical monitoring in the Pennine Dales ESA 1987-1995. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. The ESA covers a wide variety and many thousands of historical features, many of which have yet to be officially recorded. The monitoring programme looked for change in the condition of historical features over two years. The impact of changes in land cover and linear features were also examined.
ADAS. (1996e) Bird monitoring in the Pennine Dales ESA 1991-1995. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. Prior to the launch of the ESA scheme in 1987, a number of wader species which breed in the Dales were under threat, mainly from the drainage and improvement of damp pastures and rough grazing. Intensification of farming on meadow land and the move towards silage production were particular threats to yellow wagtails. Breeding wader monitoring showed a significant relationship between the presence of rushes and bird registrations.
176 ADAS. (1997a) Biological monitoring of moorland in the North Peak ESA 1988-1996. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. A report describing monitoring activities carried out in the North Peak ESA, in order to examine elements of management prescriptions and their effects on the moorland in the ESA. Since the Second World War, agricultural changes have led to a loss of heather moorland and a decrease in its wildlife value due to inappropriate management. Sheep numbers and grazing pressure are highest on the heather margins, where heather cover is broken and mixed with palatable grasses. Heather cover has increased, particularly in areas of eroding moorland where supplementary treatments have been applied. Bracken cover is controlled by spraying and vegetation management increased by the exclusion of stock.
ADAS. (1997b) Monitoring of breeding birds in the North Peak ESA 1994-1996. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. The area holds nationally important populations of a number of species associated with the moorland or moorland fringe: merlin, golden plover, dunlin, curlew, short-eared owl and twite, plus significant populations of red grouse, ring ouzel, whinchat, wheatear and meadow pipit. Monitoring surveys in 1994 and 1996 provided estimates of breeding birds numbers in 24 tetrads. Red grouse and meadow pipit were the two most abundant species in both years. Numbers of breeding birds for the majority of species were greater in 1996 than 1994.
ADAS. (1997c) Landscape monitoring in the North Peak ESA 1988-1996. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. The landscape monitoring programme has looked for change by monitoring landscape elements in terms of losses and gains, and by assessing the effect of changes on the character of each landscape type. The farmland fringe is between moorland and inbye land, and is often abandoned to rough grazing or moorland. It covers 6% of the ESA. A reduction in the area of bracken has occurred during the monitoring period, mainly due to the ESA scheme. Stone walls have deteriorated with reversion to rough grazing.
ADAS. (1997d) Environmental monitoring in the South West Peak ESA 1993-1996. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. The report summarises the environmental monitoring programme undertaken from 1993-1996. By the end of 1996, 57% of moorland, 55% of permanent grassland and 70% of rough grazing were under ESA agreement, helping to maintain the upland mosaic. The majority of moorland fringe; acid grassland, bracken and rough grazing, were under ESA agreement by 1996. Large declines in the breeding populations of several bird species, particularly curlew, snipe, lapwing and ring ouzel were recorded between years, which could be due to a loss of wetter ground. Sheep grazing continues to be concentrated on heather margins.
ADAS. (1997e) Environmental monitoring in the Exmoor ESA 1993-1996. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. The ESA covers 80,615 ha of the north Devon and west Somerset uplands of Exmoor and the Brendon Hills. Approximately 85% of this area is agricultural land. Enclosed rough/unimproved grassland is scarce and is concentrated around the fringe of the upland plateau. Bracken is found mainly on the sheltered lower slopes and steeper gullies. The loss of moorland has largely been halted with little net change between the 1980s and 1993. The mosaic of dwarf-shrub heath is important for birds such as whinchat and stonechat.
ADAS. (1997f) Environmental monitoring in the Lake District ESA 1993-1996. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. The ESA is characterised by extensive fell sheep grazing with cattle on the lowland fringes. Farming intensification since the Second World War, particularly in the 1970s and 1980s has led to increased stocking densities. This has led to more intensive use of inbye land and traditional pastures and meadows have been lost or degraded.
ADAS. (1998a) Environmental monitoring in the Dartmoor ESA 1994-1997. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK. Improved grassland was the most extensive class of land cover within the ESA in 1994. On the hillside, below the moorland are less improved pastures and hay meadows. Unimproved, species-rich hay meadows are rare. Surveys of moorland vegetation show that the majority of heather is suppressed due to heavy grazing, with a reduction in vegetation height and an increase in species suited to grazing.
ADAS. (1998b) Environmental monitoring in the Shropshire Hills ESA 1994-1997. ADAS report to the Ministry of Agriculture, Fisheries and Food, UK.
177 The report summarises the environmental monitoring programme undertaken from 1994-1997. In 1993/94, only 16% of the ESA was covered by semi-natural vegetation of unimproved grassland, heath, bracken and scrub and most of this was restricted to the upland regions By 1997, only a third of this vegetation was under ESA agreement. The threat to moorland and permanent grassland due to intensive management of the land but also insufficient management was the main reason for the designation of the ESA in 1994.
Aitchison, J. & Medcalf, K. (1994) Common land and conservation. Biological surveys in England and Wales - A Synthesis. English Nature Research Report Number 77 (Contract F72-07-02). English Nature. Peterborough, UK. The report summarises the results of biological surveys of 913 commons in 18 counties. There is a heavy concentration of common land in the uplands of the north and west, with the highest proportions recorded in Wales. Approximately half of the common land area is grassland, much of it unimproved acidic or marshy. Nearly a quarter of the area is heathland and about 13% has been invaded by bracken. Agricultural improvement, overgrazing and lack of management are the major threats to common land.
Allen, D.S. (1995) Habitat selection by Whinchats: a case for bracken in the uplands. Heaths and moorland: cultural landscapes (eds. D.B.A. Thompson, A.J. Hester & M.B. Usher), pp. 200-205. HMSO, Edinburgh, UK. Whinchats in the uplands are associated with areas of low altitude and high bracken cover. Widespread bracken control could impact on important breeding populations of whinchats.
Allen, D.S. (2001) Factors influencing habitat associations of upland passerines. Moorland research review 1990-1995 (eds. S. Rees, R. Charles & S. Wightman), pp. 90-95. North York Moors National Park Authority, Helmsley.
Allinson, N. (2001) Moorland bird survey 1992. Moorland research review 1990-1995 (eds. S. Rees, R. Charles & S. Wightman), pp 83-89. North York Moors National Park Authority, Helmsley.
Anderson, P. & Radford, E. (1994) Changes in vegetation following reduction in grazing pressure on the National Trust’s Kinder Estate, Peak District, Derbyshire, England. Biological Conservation, 69, 55-63. This paper describes the recolonisation of moorland vegetation on the slopes of the Kinder plateau following the reduction of sheep grazing. Deschampsia flexuosa, Calluna vulgaris and Vaccinium myrtillus have all increased, but changes in other moorland species are limited.
Anderson, P. & Yalden, D.W. (1981) Increased sheep numbers and the loss of heather moorland in the Peak District, England. Biological Conservation, 20, 195-213. An increase in sheep numbers has led to changes in vegetation. There has been a reduction in heather dominated areas which are replaced by grassland communities. Invasion by bracken has increased. Mixed grassland with heather is being replaced solely with grassland though there has been an expansion of heather in areas originally dominated by cotton grass. Changes have been uphill onto the moor rather than downwards towards pasture. These vegetation changes have led to a reduction in grouse numbers, twite, ring ouzel, emperor moth and bumble-bee, though wheatear have benefited.
Andrews, J. & Rebane, M. (1994a) Pastures and Meadows. Farming and wildlife: a practical handbook for the management, restoration and creation of wildlife habitats on farms, pp. 56-81. RSPB, Sandy, Beds., UK. The best grasslands for wildlife are unimproved and have a long management history. Improved grasslands support a limited range of wildlife. The importance of these habitats is shown and management guidelines for maximising the conservation potential of pastures and meadows are given.
Andrews, J. & Rebane, M. (1994b). Hill and rough grazings. Farming and wildlife: a practical handbook for the management, restoration and creation of wildlife habitats on farms, pp. 136-167. RSPB, Sandy, Beds., UK. About 200 species of flowering plants and ferns occur only on upland grazing land. However overstocking is common and large parts of hill land have been converted to improved grassland. The importance of hill land is shown and management guidelines for maximising the conservation potential are given.
Anonymous. (1995a) High brown fritillary (Argynnis adippe). Biodiversity: The UK Steering Group Report. Volume 2: Action Plans, pp. 122. HMSO, London, UK. The high brown fritillary has declined over the last 50 years and now is extinct over 94% of its former range. Factors causing this decline include, agricultural improvement and cessation of traditional bracken management.
178 Anonymous. (1995b) Pearl-bordered fritillary (Boloria euphrosyne). Biodiversity: The UK Steering Group Report. Volume 2: Action Plans, pp. 126. HMSO, London, UK. This butterfly species has declined in the last 50 years, partly due to cessation of grazing on unimproved grassland and the abandonment of traditional bracken and gorse management. Action plan objectives to halt this decline are given.
Anonymous. (1995c) Upland oakwood. A costed habitat action plan. Biodiversity: The UK Steering Group Report. Volume 2: Action Plans, pp. 256-258. HMSO, London, UK. Upland oakwoods cover about 70,000 ha in the UK, but have declined by 30-40% in area over the last 60 years, as a result of replanting by conifers, clearance for development and conversion to rough grazing. In Wales, the woods are the main breeding areas for red kites.
Anonymous. (1995d) Unimproved neutral grasslands. Habitat statement. Biodiversity: The UK Steering group Report. Volume 2: Action Plans, pp. 280. HMSO, London, UK. Unimproved neutral grassland covers less than 15,000 ha in the UK. These grasslands are managed as traditional hay meadows or pastures, and contain a high proportion of broad-leaved herbaceous species. They provide important feeding areas for moorland birds.
Anonymous. (1995e) Acid grasslands. Habitat statement. Biodiversity: The UK Steering Group Report. Volume 2: Action Plans, pp. 281. HMSO, London, UK. There are over 1,200,000 ha of acid grasslands in the uplands of Britain Much of it of low botanical interest and is the product of poor management. They are affected by inappropriate grazing regimes, forestry planting, encroachment by bracken and agricultural improvement.
Anonymous. (1995f) Upland heathland. Habitat Statement. Biodiversity: The UK Steering Group Report. Volume 2: Action Plans, pp. 295-296. HMSO, London, UK. Upland heath lies above the upper edge of enclosed agricultural land and is dominated by dwarf shrubs. This is good habitat for twite, golden plover, hen harrier and merlin. The habitat is affected by heavy grazing, afforestation and pasture improvement.
Anonymous. (1995g). Water Vole (Arvicola terrestris). Species Action Plan. In: Biodiversity: The UK Steering Group Report. Volume 2: Action Plans, pp. 82. HMSO, London, UK.
Anonymous (2001a) Upland Heathland. UK Biodiversity Habitat Action Plan. http://www.ukbap.org.uk/plans/habitats/NBNSYS0000004619.htm
Anonymous (2001b) Upland Mixed Ashwoods. UK Biodiversity Habitat Action Plan. http://www.ukbap.org.uk/plans/habitats/NBNSYS0000004606.htm
Anonymous (2001c) Upland Calcareous Grassland. UK Biodiversity Habitat Action Plan. http://www.ukbap.org.uk/plans/habitats/NBNSYS0000004616.htm
Anonymous (2001d) Acid grasslands. UK Biodiversity Habitat Action Plan. http://www.ukbap.org.uk/plans/habitats/NBNSYS0000004547.htm
Anonymous (2001e) Upland Hay Meadows. UK Biodiversity Habitat Action Plan. http://www.ukbap.org.uk/plans/habitats/NBNSYS0000004614.htm
Anonymous (2001f) Juniper (Juniperus communis). UK Biodiversity Species Action Plan. http://www.ukbap.org.uk/plans/species/NBNSYS0000004634.htm
The Arkleton Trust. (1982) Schemes of Assistance to farmers in Less Favoured Areas of the EEC. The Arkleton Trust, Dumfriesshire, UK. The study compares principal schemes of financial assistance to farmers in Less Favoured Areas. In 1982, 7.6 million ha in the United Kingdom were designated as less favoured, covering 41% of the total land area and containing 51,400 farms over 3 ha. Grants are given for land improvements, such as drainage, which will influence the hill-edge habitat.
179 Armstrong, H.M. & Milne, J.A. (1995) The effects of grazing on vegetation species composition. Heaths and moorland: cultural landscapes (eds. D.B.A. Thompson, A.J. Hester & M.B. Usher), pp. 162-173. HMSO, Edinburgh, UK. The paper describes the extent to which moorland plants can withstand grazing and the effects of grazing on plant species composition. This can be used to predict the consequences of changes in stocking rate on the grazing pressure to which vegetation types in a hill-grazing system are likely to be subject.
Asher, J., Warren, M., Fox, W., Harding, P., Jeffcoate, G. & Jeffcoate, S. (2001) The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press, Oxford, UK.
Askew, D.R. (1993) Pennine Dales ESA: grassland management and nature conservation interest. Grassland management and nature conservation. BGS Occasional Symposium No. 28 (eds R.J. Haggar & S. Peel), pp. 179-184. British Grassland Society, Reading, UK. Certain management techniques are associated with greater conservation interest, including grazing patterns, fertiliser rates and hay-making regimes. Traditional management is encouraged by the ESA.
Avery, M. & Leslie, R. (1990). Birds and Forestry. T. & A.D.Poyser, London.
Avery, M.I. (1989) Effects of upland afforestation on some birds of the adjacent moorlands. Journal of Applied Ecology, 26, 957-966. Bird numbers were estimated on areas adjacent to conifer plantations at 62 sites in three areas of northern Scotland, but only golden plover, dunlin, curlew and red grouse were numerous enough for detailed analysis. Overall, in some areas the numbers of birds varied both positively and negatively with distance from the forest edge, but this was mainly due to vegetation differences probably caused by the growth of trees or changes in management. There appeared to be no edge effects for birds around forestry plantations in northern Scotland, which could be of conservation importance.
Babbs, S. (1998) Survey of breeding waders on agricultural land in the Forest of Bowland 1998. Unpublished Report. RSPB, Sandy, Beds., UK. Within the AONB, there are 42,500 ha of agricultural land, much of which is ‘upland fringe’. In 1993, this land supported important densities of breeding lapwing, curlew, oystercatcher and other waders. Since then, lapwing, snipe and redshank have declined but curlew have increased.
Backshall, J., Manley, J. & Rebane, M. (eds.). (2001) The Upland Management Handbook. English Nature, Peterborough, UK. The report is a guide to the management needs of the uplands and identifies key principles for action. Of particular use are: Chapters 2 - Wildlife and land use in the uplands, 6 - Moorland, 7 - Meadows and pasture, and 8 - Woodland and scrub. All sections detail plant and animal species, conservation importance and policies and management techniques.
Bain, C. (1987) Breeding wader habitats in an upland area of north Wales (Hiraethog). Unpublished report. RSPB, Sandy, Beds., UK. Lapwings were found to be strongly associated with a mosaic of damp, enclosed pastures, ploughed land and damp, coarse grassland in the valley bottom. Curlew and snipe preferred damp, coarse grassland on the higher altitude ground as well as in the valley bottom. Redshank were located in very wet grassland and dunlin and golden plover were found on high altitude grassland. All waders avoided dry pastures. Replacement of old, damp pastures by re-seeded fields is detrimental to breeding waders.
Baines, D. (1988a) The effects of improvement of upland, marginal grasslands on breeding waders (Charadriiformes) and invertebrates. PhD Thesis, University of Durham, UK. A short history of the moorland fringe is given. Grassland improvement led to a reduction in breeding waders and a decline in breeding success by lapwings. An increase in earthworms and beetles other than carabids was noted, but there was a decrease in spiders and carabids.
Baines, D. (1988b) The effects of improvement of upland, marginal grasslands on the distribution and density of breeding wading birds (Charadriiformes) in northern England. Biological Conservation, 45, 221-236. This study covers grasslands at the upper altitudinal limit of agricultural practice. Improvement has led to a reduction of snipe, redshank, curlew and lapwing but an increase in oystercatchers. Overall, there has been a
180 decline in the number of waders. These changes in wader numbers are due to a loss of Juncus, wet-loving invertebrates and an increase in earthworms.
Baines, D. (1989) The effects of improvement of upland, marginal grasslands on the breeding success of Lapwings Vanellus vanellus and other waders. Ibis, 131, 497-506. In northern England, densities of lapwings on improved grassland were 69% lower than on adjacent unimproved fields. Fledging success was higher on unimproved land. This lower productivity on improved grassland is responsible for the population decline in such areas.
Baines, D. (1990a) Black grouse densities and habitat requirements. The Game Conservancy Review of 1989, pp. 136-138. The Game Conservancy, Fordingbridge, UK. Grouse in England prefer the edge of moorland where heather fringes marginal farming areas and where trees are absent. Scottish grouse prefer moorland with woodland. The decline of the species is associated with habitat loss.
Baines, D. (1990b) The roles of predation, food and agricultural practice in determining the breeding success of the lapwing (Vanellus vanellus) on upland grasslands. Journal of Animal Ecology, 59, 915-929. Lapwing breeding densities decreased by 74% on pastures and 56% on meadows following improvement of upland grasslands, due to increased predation of clutches, reduction in invertebrate food and/or its availability, and greater destruction of clutches.
Baines, D. (1993) Recent trends in black grouse numbers. The Game Conservancy Trust Review of 1992, pp. 133-135. The Game Conservancy, Fordingbridge, UK. The Yorkshire Dales is good for grouse as the region has large areas of moorland edge and rough grazing allotments. Overgrazing reduces the availability of good habitat.
Baines, D. (1994a) The black grouse report - a summary. The Game Conservancy Trust Review of 1993, pp. 125-126. The Game Conservancy, Fordingbridge, UK. The population of black grouse is declining on semi-natural moorland. Most leks occur on land between enclosed fields and unenclosed moorland. In the Pennines, the birds are associated with rushy allotments and sheep-grazed grass moorland. Birds on heavily grazed moors raise fewer chicks. A summary of habitat restoration grants is given.
Baines, D. (1994b) Seasonal differences in habitat selection by black grouse Tetrao tetrix in the northern Pennines, England. Ibis, 136, 39-43. Heather moor and bogs are the preferred habitats throughout the year except during the breeding season. Enclosed fields on edge of moors are regularly used in autumn and winter. Overgrazed grass moorland is avoided, apart from during the summer. Enclosed rough grazing is favoured during summer.
Baines, D. (1995) Habitat management for black grouse. The Game Conservancy Review of 1994, pp. 142. The Game Conservancy, Fordingbridge, UK. Black grouse prefer a mosaic of heather moorland margins, rough grazing, woodland edges and pre-thicket forestry. The habitat quality is frequently poor due to overgrazing on moorland margins by sheep and deer.
Baines, D. (1996) The implications of grazing and predator management on the habitats and breeding success of black grouse Tetrao tetrix. Journal of Applied Ecology, 33, 54-62. Large-scale losses of moorland fringe, primarily through agricultural expansion and intensification, and afforestation have led to a decline in bird numbers. Grazed ground vegetation is less favoured for breeding and supports fewer invertebrates.
Baines, D. & Hudson, P.J. (1995) The decline of black grouse in Scotland and northern England. Bird Study, 42, 122-131. Black grouse prefer a combination of woodland, moorland edge and rough grazing. Improving agriculture has led to moorland fringes being enclosed, drained and reseeded. Increased grazing has caused the loss of heather and dwarf shrubs. Numbers of black gouse have declined due to a reduction in favoured habitats.
Baines, D., Warren, P. & Calladine, J. (2002) Spatial and temporal differences in the abundance of black grouse and other moorland birds in relation to reductions in sheep grazing. Aspects of Applied Biology, 67, 245- 252.
181 Agricultural policies have led to the degradation, fragmentation and loss of moorland and moorland fringe habitats, primarily through overgrazing. This overgrazing can have severe implications for several moorland bird species. Agri-environment schemes have been introduced, and the impact of such schemes on moorland birds in the north Pennines are discussed. A reduction in sheep has led to more heath species, fewer rushes and a loss of variation in vegetation structure. Breeding waders have declined, as well as grey partridge, whereas black grouse have benefited from sheep reduction. The development of habitat mosaics is best for bird conservation in the uplands.
Baines, D., Wilson, I.A. & Beeley, G. (1996) Timing of breeding in Black grouse Tetrao tetrix and Capercaillie Tetrao urogallus and distribution of insect food for the chicks. Ibis, 138, 181-187. In northern Pennines, broods are found on grass-dominated moorland or enclosed rough grazing of grass and rushes. These habitats have taller vegetation and more invertebrates, particularly sawfly larvae. Hatching time corresponds to the peak biomass of sawfly larvae. Overgrazing reduces quality of brood-rearing habitats.
Ball, D.F. (1984) Studies by ITE on the impact of agriculture on wildlife and semi-natural habitats in the uplands. Agriculture and the Environment. ITE symposium No. 13 (ed. D. Jenkins), pp. 155-162. Institute of Terrestrial Ecology, Cambridge, UK. Summary of the major impacts of agriculture on uplands, the work that has been done by ITE and the research which needs to be done.
Ball, D.F., Dale, J., Sheail, J., Dickson, K.E. & Williams, W.M. (1981) Ecology of vegetation change in upland landscapes. Part 1: General Synthesis. Bangor Research Station Occasional Paper No. 3. Institute of Terrestrial Ecology, Bangor, Gwynedd, UK. Changes in the upland landscape may result from either major alterations in land use, such as comprehensive agricultural improvement, or more gradually from modification of traditional management methods. This report covers the findings of an investigation of 12 study areas, to determine their main classes of upland vegetation. Upland margin land contains a full range of vegetation classes but has improved pastures dominant, with limited shrubby heath. Variations between study areas are the result of land management. Future vegetation change is likely to be concentrated along the moorland fringe.
Ball, D.F., Dale, J., Sheail, J. & Heal, O.W. (1982) Vegetation change in upland landscapes. Institute of Terrestrial Ecology, Cambridge, UK. Report on the changes in vegetation and land use, how uplands have developed and factors affecting the future vegetation structure.
Ball, D.F., Dale, J., Sheail, J. & Williams, W.M. (1981a) Study Area 5: Heptonstall, West Yorkshire. Ecology of vegetation change in upland landscapes. Part 2: Study areas. Bangor Occasional Paper No. 3. pp. 54-73. Institute of Terrestrial Ecology, Bangor, Gwynedd, UK. The study area is situated in the Southern Pennines. Most of the area is in the ‘upland fringe’ land type, with some upland margin land in the east. Agricultural improvement of the moorland can be traced to the 12th century and moorland reclamation from the 14th and 15th centuries. Ordnance Survey maps from 1850 to 1958 show that the moorland fringe occupies 110 ha of which about 20 ha represent those parts of the moorland that have been reclaimed for agriculture during the past 150 years. The moorland fringe is concentrated in the upland and steep upland land types. Current vegetation and potential vegetation change are discussed.
Ball, D.F., Dale, J., Sheail, J. & Williams, W.M. (1981b) Study Area 8: Ysbyty Ystwyth, Dyfed. Ecology of vegetation change in upland landscapes. Part 2: Study areas. Bangor Occasional Paper No. 3. pp. 85-105. Institute of Terrestrial Ecology, Bangor, Gwynedd, UK. The study area is situated in the west of the Cambrian Mountains region. Upland margin occurs around the village of the same name and is scattered along the Wstwyth Valley. Ordnance Survey mapping between 1901 and 1964 show a moorland fringe of 568 ha which includes 320 ha of moorland that has been afforested since the mid 1950s. The non-afforested fringe occurs mostly in the upland margin and steep upland land types. Current vegetation and potential vegetation change are discussed.
Barber, D.D. (1986) Bracken on the North York Moors: the agricultural problem. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 87-91. Parthenon Publishing, Lancaster, UK. Most of the North York Moors lie within the Less Favoured Areas designation. The area of bracken is estimated to be 11,600 ha, of which approximately one-third is on enclosed in-bye land, with the drier, better soils on the
182 slopes between the plateau heather moorland and the lower valley land. Bracken-infested land is unproductive. The costs of bringing this land back into productivity are given.
Barber, D.D. (1990) North York Moors Integrated Moorland Management Programme. Interim report for 1989. Report of annual consultation meeting, 11 June 1990. ADAS, Pickering, UK. A study to study the effects of large-scale bracken control on an area of open moorland.
Bardgett, R.D., Marsden, J.H. & Howard, D.C. (1995) The extent and condition of heather on moorland in the uplands of England and Wales. Biological Conservation, 71, 155-161. A large proportion of heather moorland in England is dominant and in good condition and only a small proportion shows signs of overgrazing and neglect. In Wales, heather is in a poor condition. Most heather occurs in the west Midlands, south Wales and north-east England.
Barnes., J.A.G. (1970) Birds. Natural History of the Lake District (eds. G.A.K. Hervey & J.A.G. Barnes), pp. 149-175. Frederick Warne, London, UK. Gives a brief description of the habitat associations of black grouse on the hill-edge in the Lake District.
Bates, S.M. (1992) Trees in pasture: their impact on bird communities of the ffridd in north Wales. Unpublished Master of Science dissertation. University College of North Wales, Bangor, UK. The ffridd in Wales supports higher populations of song bird species than found on lowland farmland, though numbers were generally lower than for woodland habitats. The presence of trees and bracken beds create suitable habitat conditions for a range of species, though the abundance of invertebrate food is probably a significant factor. Whinchat are particularly important in the ffridd.
Bell, J.R., Wheater, C.P. & Cullen, W.R. (2001) The implications of grassland and heathland management for the conservation of spider communities: a review. Journal of Zoology, London, 255, 377-387. Both the intensity and type of habitat management affect spider communities. High intensity management leads to spider communities lacking in diversity and dominated by a few species affiliated with bare ground. Low intensity management produces more complex communities with more niches for aerial web spinners and climbing spiders. Management for spiders may conflict with rare plant conservation.
Bell, M.V. (1979) The status of golden plover (Pluvialis apricaria) and dunlin (Calidris alpina) in Upper Wharfedale. Naturalist, 104, 95-100. Golden plover were present on all moorlands regardless of habitat type. Dunlin preferred wetter cottongrass areas and were affected by moor drainage schemes leading to agricultural improvement and forestry.
Bell, M.V., Buckland, S.T. & Picozzi, N. (eds.) (1990) The Birds of North-east Scotland. North-east Scotland Bird Club, Aberdeen. Quantifies habitat associations of upland bird species in summer and winter in north-east Scotland.
Bibby, C.J. (1986). Merlins in Wales: site occupancy and breeding in relation to vegetation. Journal of Applied Ecology, 23, 1-12. Breeding success of the merlin appears to be related to habitat. The birds prefer heather moorland adjoining bracken slopes and established farmland. The lower slopes are in demand for afforestation and agricultural improvement which are likely to cause conflict.
Bibby, C.J. (1987) Foods of breeding Merlins Falco columbarius in Wales. British Birds, 34, 64-70. A study of merlin prey remains collected throughout Wales showed that birds nesting nearer moorland edges had a more varied diet. They ate a wide variety of predominantly small, open-country birds. This varied diet led to the laying of larger eggs.
Bibby, C.J. (1988) Impacts of agriculture on upland birds. Ecological change in the uplands (ed. M.B. Usher & D.B.A. Thompson), pp. 223-236. Blackwell Scientific Publications, Oxford, UK. Patterns in moorland vegetation and associated bird communities are shaped mainly be agriculture. Changes in vegetation due to grazing and reseeding have the most impact. Birds of heather-dominated moorland are the most affected.
Bibby, C.J., Phillips, B.N. & Seddon, A.J.E. (1985) Birds of restocked conifer plantations in Wales. Journal of Applied Ecology, 22, 619-633.
183 Details on how afforestation affects bird species.
Birnie, R.V., Miller, D.R., Horne, P.L., Leadbeater, S. & MacDonald, A. (2000) The potential distribution and impact of bracken in upland Scotland: an assessment using a GIS-based niche model. Annals of Botany, 85 (Supplement B), 53-62. In Scotland, bracken impacts on 70% of the national area of ‘good rough grassland’, and 31% of the ‘poor rough grassland’ category. Sixteen percent of the national area of ‘heather moorland’ is impacted. There are strong regional variations in these impacts which may have implications for future bracken management.
Blackstock, T.H., Stevens, D.P. & Yeo, M.J.M. (1997) Conservation and management of Molinia and Juncus pastures in Wales, with reference to agri-environment schemes. Grassland management in ESAs. BGS Occasional Symposium No. 32 (ed. R.D. Sheldrick), pp. 150-159. British Grassland Society, Reading, UK. In Wales, wet pasture habitats, with Molinia and Juncus communities are widely distributed in both the lowlands and the unenclosed uplands. The habitat is protected in agri-environment schemes, such as ESAs. The lowland wet pastures have a specialist flora and fauna, and are important bird habitats especially for breeding waders. In many areas, pasture is accompanied by dry grassland, flush, heath scrub and bracken communities. Variation in the cover and conservation importance of wet pastures in Wales are assessed.
Boyce, D. (2000a) The status of the high brown fritillary Argynnis adippe, Dartmoor National Park - 2000. Unpublished report for Dartmoor National Park Authority, Butterfly Conservation and English Nature. The upland fringes of Dartmoor are one of three remaining strongholds for the high brown fritillary. It breeds on south-facing bracken slopes with an abundance of the food plant common dog-violet Viola riviniana. Core sites tend to be at low altitudes, on common land with bracken slopes grazed by cattle and ponies. The loss of cattle and pony grazing from a number of sites has resulted in bracken stands becoming tall and rank and scrub encroachment. This has led to a decline in fritillary numbers. The control of European gorse and other scrub is critical, but burning must be strictly controlled.
Boyce, D. (2000b) A review of the importance of Dartmoor’s common land and wet pastures for priority and threatened invertebrates. Unpublished report for Butterfly Conservation, Dartmoor National Park Authority and English Nature. The commons and wet pastures of Dartmoor support a range of nationally and internationally significant invertebrate species that need extensive grazing of their habitats. The key management is to maintain the extensive, mixed grazing of these habitats. However, higher parts of the commons can be excessively grazed. Lowering the summer stocking level and removing stock over the winter would benefit vegetation higher up the hills, but peripheral areas of the commons could become undergrazed. Management prescriptions need to take into account the needs of these invertebrate assemblages.
Brack, E.V. (1978) Vegetational changes in upland landscapes. Landscape Research, 3, 8-10. The spread of bracken in upland pastures is a major problem of hill areas. However, the decline of heather and the consequent increase of mat-grass, and the invasion of Fescue grassland are also important. Most vegetation changes are due to changes in grazing type and pressure. Research at Ingleborough Site of Special Scientific Interest has shown that the area dominated by mat-grass has increased by 20% in seven years.
Brindley, E., Lucas, F. & Waterhouse, M. (1992) North Staffordshire Moors: survey 1992. Unpublished report. RSPB, Sandy, Beds., UK. Resurvey of the area covered in 1985. Breeding waders had declined along with ring ouzel and black grouse. These changes may be due to a loss of the mosaic of field uses, due to an increase in silage production and increased grazing pressure.
Brown, A. (1992) Habitats and species. The UK Environment, pp. 130-131. HMSO, London, UK. Definition and distribution of upland areas in Great Britain. Approximately 24% of GB land area is marginal agricultural land and about 21% is hill pasture and moorland. Overgrazing has resulted in heather moorlands changing to grassland.
Brown, A.F. (1993) The status of golden plover Pluvialis apricaria in the south Pennines. Bird Study, 40, 196- 202. Population of golden plover is relatively stable. The birds are associated with flat land at higher altitude, away from enclosed land. They avoid steep slopes, low altitude and a high percentage of grass and bracken which often occur at edge of unenclosed land.
184 Brown, A.F. & Bainbridge, I.P. (1995) Grouse moors and upland breeding birds. Heaths and moorland: cultural landscapes (eds. D.B.A. Thompson, A.J. Hester & M.B. Usher), pp. 51-66. HMSO, Edinburgh, UK. Moorlands managed for grouse are not necessarily of high value for other bird species. Other upland habitats support important bird populations. Grouse moors are important for some raptors such as merlins and hen harriers, but other species occur in a wide variety of habitats. Vegetation structure may be more important then vegetation type.
Brown, A.F., Crick, H.Q.P. & Stillman, R.A. (1995) The distribution, numbers and breeding ecology of Twite Acanthis flavirostris in the south Pennines of England. Bird Study, 42, 107-121. Breeding birds prefer moorland edge with vegetation over 5 cm high. Current upland management practices may not be ideal for maintaining a breeding bird population.
Brown, A.F. & Stillman, R.A. (1993) Bird-habitat associations in the eastern Highlands of Scotland. Journal of Applied Ecology, 30, 31-42. A number of factors are associated with the distribution and abundance of upland breeding birds: altitude, gradient, and amount of vegetation cover. Whinchat were associated with high bracken cover and skylark with low altitude areas dominated by grass and bracken.
Brown, A.F. & Stillman, R.A. (1998). The return of the merlin to the south Pennines. Bird Study, 45, 293-301. Highest nesting density of merlin was found 0.25-1.5 km from the moorland edge; close to the margins of enclosed farmland which held high densities of songbird prey.
Brown, A.F., Stillman, R.A. & Gibbons, D.W. (1995) Use of breeding bird atlas data to identify important bird areas: a northern England case study. Bird Study, 42, 132-143. Shows tetrad-scale distribution maps of upland birds in the Lake District and northern Pennines derived from the BTO Breeding Bird Atlas for 1988-91.
Brown, R.W. (1986). Bracken in the North York Moors: its ecological and amenity implications in national parks. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 77-86. Parthenon Publishing, Lancaster, UK. It is unlikely that bracken will be totally eradicated from moorland, but its spread must be controlled for the long-term economic and ecological interests of the moorland. Bracken is a normal part of the vegetation on the steeper, well-drained marginal slopes of the North York Moors. About 20% (101 km2) of the National Park is dominated by the fern. There is evidence that it is encroaching into moorland at a rate of 120 ha per year. The positive and negative qualities of bracken and the need for bracken control are discussed.
Browne, S., Vickery, J. & Chamberlain, D. (2000). Densities and population estimates of breeding Skylarks Alauda arvensis in Britain in 1997. Bird Study, 47, 52-65. Marginal upland and upland areas support lower densities of skylarks but have 34% of the estimated national breeding population. The population in these areas has declined which may be linked to declines in lowland areas, due to a loss of preferred habitat.
Bub, H. (the late), Oelke, D. & Gillings, S. (1997) Twite. The EBCC Atlas of European Breeding Birds (eds. W.J.M. Hagemeijer & M.J. Blair), pp. 720-721. T & AD Poyser, London, UK. Describes distribution of breeding twite in Europe. Emphasizes conservation importance of breeding populations in Britain and Norway.
Buckley, T.E. & Harvie-Brown, J.A. (1891) A Vertebrate Fauna of Orkney. David Douglas, Edinburgh, UK. Contains a description of agricultural improvement of hill-edge habitats in Orkney in the 19th Century and their negative effects on bird populations.
Bunce, R.G.H. (1988). The impact of afforestation on semi-natural vegetation in Britain. Wildlife management in forests (ed. D. Jardine), pp. 54-59. Institute of Chartered Foresters, Edinburgh, UK. The majority of forestry planting occurs in the uplands. Apart from unplantable wet bog vegetation, all the main categories of upland vegetation will be affected by afforestation.
185 Bunce, R.G.H. & Barr, C.J. (1988). The extent of land under different management regimes in the uplands and the potential for change. Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 415- 426. Blackwell Scientific Publications, Oxford, UK. There are difficulties in defining uplands, their extent and land use. The inbye land is within the mountain wall and is cultivated. Outbye land is in agricultural use but not directly managed. Agriculture is the main use so any change in policy will influence hill ecosystems. There has been a loss of vegetation through agricultural improvement, and to coniferous forestry.
Bunce, R.G.H. & Barr, C.J. (Unknown). Vegetation and landscape analysis for 1 km squares in Wales. Institute of Terrestrial Ecology, Cumbria, UK.
Bunce, R.G.H., Howard, D.C., Hallam, C.J., Barr, C.J. & Benefield, C.M. (1993). Ecological consequences of land use change. Institute of Terrestrial Ecology, Cambridge, UK. The ITE land classification system provides a system for classifying the environment of Britain; the distribution and total area of the main vegetation types and land uses. This classification has been used as a sampling framework for further surveys in 1978 and 1984. The monitoring of landscape change project (MLC) was based on the interpretation of aerial photographs and shows land cover change from the 1940s to the early 1980s. This survey showed that land cover categories have changed less in marginal uplands than in lowland groups. Improved grass increased in the 1940s but then stabilised. The area of cropped land increased in the 1980s, and upland grass has declined. Afforestation is the major land use change. Socio-economic data have been compiled with the land classification framework.
Bunce, R.G.H. & Smith, R.S. (1978) An ecological survey of Cumbria. Cumbria County Council & Lake District Special Planning Board, Kendal, Cumbria, UK. Cumbria is the second largest county in England but has the lowest population. An ecological survey of Cumbria was undertaken in ordered to produce a classification of the county using information recorded on Ordnance Survey maps. Ground surveys would provide an interpretation of the vegetation types produced from analysis of the map data, and the input of ecological information in planning activities was assessed. The plant composition of vegetation types ranging from lowland cultivated arable to badly-drained upland moor are discussed.
Burfield, I.J. (2002) The breeding ecology and conservation of the ring ouzel Turdus torquatus in Britain. PhD Thesis, Queens’ College, University of Cambridge, UK.
Burn, A. (1988) Annex 4: Bracken and nature conservation. Bracken in Wales. The Senior Technical Officer’s Group, Wales, pp. 47-55. Nature Conservancy Council, Bangor, UK. In the uplands where woodland and scrub are rare, bracken can act as a partial canopy substitute, allowing a woodland ground flora. Invasion of heathland is aggravated by management regimes and bracken may invade grassland on marginal agricultural land and the ffridd. The importance of bracken to the major animal groups are listed, along with the undesirable aspects in relation to nature conservation.
Buse, A. (1992). Environmental effects of land use change, as identified by habitat recording: a case study in the Llyn Peninsula, Wales. Journal of Environmental Management, 35, 131-151. Between 1972 and 1987, there has been an increase in improved grassland with a loss of wet and less managed areas. The current ESA designation has helped to restrict improvement in the lower upland areas.
Butterfield, J. & Coulson, J.C. (1983). The carabid communities on peat and upland grasslands in northern England. Holarctic Ecology, 6, 163-174. Upland grassland carabid communities show little affinity to those on lowland grasslands or ‘grass heaths’ in southern England. Upland grasslands have several characteristic communities, partly due to the habitat preferences of certain carabids. Most are rarely restricted to a single vegetation or soil type. There may be further unstudied carabid communities on upland grasslands.
Butterfield, J., Coulson, J.C. & Wanless, S. (1981). Studies on the distribution, food, breeding biology and relative abundance of the Pygmy and Common shrews (Sorex minutus and S. araneus) in upland areas of northern England. Journal of Zoology, London, 195, 169-180. Pygmy shrews are more abundant than common shrews, particularly on heather, cotton-grass and moor-rush dominated areas. Distribution is related to the fact that pygmy shrews feed on invertebrates such as spiders, while common shrews eat earthworms, which are mainly absent on peatlands.
186 Butterfield, J., Luff, M.L., Baines, M. & Eyre, M.D. (1995). Carabid beetle communities as indicators of conservation potential in upland forests. Forest Ecology and Management, 79, 63-77. In northern England, large areas of marginal agricultural upland have been planted with conifers. Afforestation disrupts the characteristic ground beetle communities of open habitats and species richness is low in closed canopy plantations. However, over the whole forestry cycle, woodland is as species rich as surrounding habitats. Most species occur in clear-felled areas and there is a decrease in the numbers of rare species.
Byrkjedal, I. & Thompson, D.B.A. (1998) Tundra plovers. T & A.D. Poyser, London. A comparative study of the taxonomy, ecology and behaviour of grey, golden, Asiatic golden and Pacific golden plovers. Discusses the potentially limiting effects of hill-edge pastures on the size of breeding populations of golden plover.
Cadbury, C.J. (1999). Grazing and other management of upland vegetation: a review with special reference to birds. RSPB, Sandy, Beds., UK. There have been considerable losses and degradation of the upland habitat due to afforestation, pasture improvement, bracken encroachment, over-grazing and poor burning management. These factors are discussed along with current agricultural and conservation policies. Details of the upland birds of conservation importance are given.
Callion, J. (1994) Whinchat. The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991 (eds. D.W. Gibbons, J.B. Reid & R.A. Chapman), pp. 306-307. T.& A.D. Poyser, London, UK. Presents distribution and density maps of breeding whinchat in Britain and Ireland.
Carey, P.D. (1998). Monitoring and evaluation of the Countryside Stewardship Scheme. Topic report on upland agreements. Unpublished final report. Institute of Terrestrial Ecology, Monkswood, UK. The report gives an evaluation of upland agreements within the Countryside Stewardship Scheme. Specific objectives include: restoring moorland and converting improved land to moorland, conserving flower-rich hay meadows and restoring in-bye and in-take or allotment pastures to encourage ground nesting birds, conserving archaeological or historical features, and restoring upland features such as stone walls and hedgerows.
Cayford, J. & Hope Jones, P. (1989). Black grouse in Wales. RSPB Conservation Review 3, pp. 79-81. RSPB, Sandy, UK. Heavy grazing of moorland, the removal of birch scrub and conversion of semi-natural vegetation to improved pasture have resulted in the loss of black grouse habitats. Conifer plantations are only temporarily favourable.
Cayford, J.T. (1990) The distribution and habitat preferences of black grouse in commercial forests in Wales: conservation and management implications. Transactions of the XIXth Congress of the International Union of Game Biologists, September 1999, Trondheim, Norway, pp. 435-447. Norwegian Institute for Nature Research, Trondheim. Describes a radio-tracking study of black grouse in upland conifer forests in north Wales. Presents data on home range, habitat preferences and season variation in diet.
Cayford, J.T. & Walker, F. (1991). Counts of male black grouse Tetrao tetrix in North Wales. Bird Study, 38, 80-86. Conversion of semi-natural vegetation to improved pasture, overgrazing of moorland, afforestation and the use of herbicides have all been implicated in the recent population decline of black grouse.
CEAS Consultants (Wye) Ltd & Wye College (University of London). (1993a). Review of the impact of extensive livestock farming systems on nature conservation and the environment. Phase 1 – Final report. English Nature Research Report No. 68. English Nature, Peterborough, UK. Sheep farming is the major farming activity in the UK uplands and is a vital factor in the conservation of the vegetation and landscape. The relationship between hill and upland farming systems and upland conservation, and the problems associated with grazing intensification in a number of English uplands are reviewed. Sheep extensification could prevent further habitat degradation.
CEAS Consultants (Wye) Ltd & Wye College (University of London). (1993b). Review of the impact of extensive livestock farming systems on nature conservation and the environment. Phase 2 – Final Report. English Nature Research Report No. 69. English Nature, Peterborough, UK.
187 The introduction of an extensification scheme would help to reduce moorland overgrazing, by combining a stocking rate prescription with a nitrogen prescription. Current farming systems in the English uplands and the possible impact of extensification prescriptions are reviewed.
Charles, R., Wightman, S. & Hammond, M. (eds.) (2001). Moorland Research Review 1995-2000. North York Moors Park Authority, Helmsley, UK. The review gives an update on research work that has been carried out on the North York Moors between 1995 and 2000. This includes studies on moorland vegetation including bracken, birds, invertebrates, mapping and the economics of hill farming. Information from this research will be used in developing the Moorland Regeneration Programme.
Charles, W.N. (1981). Abundance of field voles (Microtus agrestis) in conifer plantations. Forest and Woodland Ecology. ITE symposium No. 8 (eds. F.T. Last & A.S. Gardiner), pp. 135-137. Institute of Terrestrial Ecology, Cambridge, UK. Field voles are the most abundant rodent in upland grasslands. When open ground is planted with conifers, the ground vegetation temporarily increases leading to a rise in vole numbers. Numbers decline again as the trees shade out the vegetation.
Cherrett, J.M. (1964). The distribution of spiders on the Moor House National Nature Reserve, Westmorland. Journal of Animal Ecology, 33, 27-48. In this study, grazed grassland had the lowest number of spiders present. Ungrazed or lightly grazed land tends to have tussocks of denser foliage which have a higher density of spiders. Closely grazed grassland is sparsely populated.
Cherrill, A. & McClean, C. (1995). An investigation of uncertainty in field habitat mapping and the implications for detecting land cover change. Landscape Ecology, 10, 5-21. Field surveys are used to identify the location and extent of recent changes in land cover. However, such map data can contain errors that can make this identification difficult. Field surveys using Phase 1 habitat mapping were used to create two sets of maps of part of the Northumberland National Park in 1991 and 1992. Discrepancies, equivalent to 41.2% of the total survey area were attributed primarily to differences of landcover interpretation between surveyors. Thus, estimates of land cover change derived from temporally separated field surveys should be treated cautiously.
Cherrill, A. & McClean, C. (2000). Lack of precision in mapping upland habitats and preliminary conservation assessments. Aspects of Applied Biology, 58, 167-172. Six ecologists surveyed the same upland site using Phase 1 habitat mapping. There were substantial differences between the surveyors in terms of the vegetation types identified and their areas. There was also little agreement on habitats of potential conservation value. Overall, there was considerable confusion between ecologically related vegetation types. This confusion is likely to be particularly prevalent in upland areas, because of the complex mosaics of vegetation that are usually present.
Cherrill, A.J., McClean, C., Lane, A. & Fuller, R.M. (1995). A comparison of land cover types in an ecological field survey in northern England and a remotely sensed land cover map of Great Britain. Biological Conservation, 71, 313-323. Field surveys using the Phase 1 classification are important for obtaining information on small land cover features in localised studies, while the Land Cover Map gives complete coverage of a range of broad land cover types. A comparison of these two land cover classifications in mapping dwarf-shrub vegetation and coniferous woodland in an area of northern England is made.
Cherrill, A.J. & Rushton, S.P. (1993). The Auchenorhyncha of unimproved moorland in northern England. Ecological Entomology, 18, 95-103. Auchenorhyncha are the most important invertebrate herbivores of ground foliage in upland grasslands. Research on grazed, unimproved grassland in Northumberland shows that species richness of grasses, soil pH and cover of woody plants and sedges determine the species of Auchenorhyncha present. The distributions of individual species are strongly influenced by the distributions of host plants. Species richness is greatest at sites with the least acid soils and the highest covers and numbers of grass species.
Clapham, A.R. (1978). Introduction. Upper Teesdale: the area and it’s natural history (ed. A.R. Clapham), pp. 15-17. Collins, London, UK.
188 A brief summary of the location and general features of Upper Teesdale.
Clark, G.J. (2000). Mapping past dwarf-shrub heath extent on Dartmoor. Aspects of Applied Biology, 58, 179- 184. There is concern about overgrazing on Dartmoor and the loss of dwarf-shrub heath vegetation to acidic grassland, though the distribution and timescale of this decline is difficult to determine. The success of restoration initiatives through the ESA scheme could also be increased if the former extent of dwarf-shrub heath was known. Existing maps are generally inaccurate in showing past extent and cover of this vegetation due to their relatively recent dates, the scale of mapping or the classification used. Aerial photography could provide this information, though error can occur due to the indistinct appearance of dwarf-shrubs at low coverage. Ground-checking of photographs is preferable but often not possible.
Clarke, J.L., Welch, D. & Gordon, I.J. (1995a) The influence of vegetation pattern on the grazing of heather moorland by red deer and sheep. I. The location of animals on grass/heather mosaics. Journal of Applied Ecology, 32, 166-176. How sheep and deer grazing affect vegetation at the edge of moorland.
Clarke, J.L., Welch, D. & Gordon, I.J. (1995b) The influence of vegetation pattern on the grazing of heather moorland by red deer and sheep. II. The impact on heather. Journal of Applied Ecology, 32, 177-186. How sheep and deer grazing affect vegetation at the edge of moorland.
Clifton, S.J., Ranner, D.S. & Ward, L. (1995) The conservation of juniper in Northumbria. English Nature Research Reports No. 152. English Nature, Peterborough, UK. In England, juniper is becoming increasingly scarce as a semi-natural vegetation type. In the uplands, juniper scrub is an important food source for frugivorous birds and can provide winter shelter for black grouse, particularly in the Pennines. Surveys of 130 sites in County Durham and Northumberland were undertaken in 1973 and 1994. In the 21 year period, there had been a 30% decline in the juniper population. Existing colonies were small and even-aged, being dominated by mature and old bushes, with few signs of active natural regeneration. Intensive grazing is the main factor affecting population decline.
Collins, E.J.T. (1978) The economy of upland Britain, 1750-1950: an illustrated review. CAS Paper 4. Centre for Agricultural Strategy, Reading, UK. The modern economic history of the uplands has been influenced by the Industrial and Agricultural Revolutions, and the harsh physical environment, resulting in upland agriculture being less productive. Trends in upland land use will have impacted upon the hill-edge habitat.
Cotton, D.E. & Hale, W.H.G. (1989) Vegetation changes on Ilkley Moor 1964-1984. The Naturalist, 14, 109- 114. Between 1964 and 1984, heather and bracken cover increased, while there was a reduction in crowberry and cotton grass.
Coulson, J.C. (1978) The terrestrial animals. Upper Teesdale: the area and it’s natural history (ed. A.R. Clapham), pp. 160-178. Collins, London, UK. About 7% (1454) of all species known to occur in the British Isles have been recorded from Upper Teesdale. Some groups, such as breeding birds and flies are well represented, while others such as moths, butterflies and beetles are under-represented. Animals are influenced by the distribution of food, the distribution and number of predators, climatic effects associated with altitude and the impact of herbivores on vegetation.
Coulson, J.C. (1988) The structure and importance of invertebrate communities on peatlands and moorlands, and effects of environmental and management changes. Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 415-426. Blackwell Scientific Publications, Oxford, UK. The effects of temperature are probably the most important factor limiting the distribution of invertebrates in the uplands. Arthropods show a decline in the numbers of species with increasing altitude. Grazing affects the height of vegetation and may lead to a reduction in invertebrate numbers. Afforestation leads to the loss of most of the invertebrate species associated with heathland, due to a change in ground vegetation. It is unknown whether the invertebrate species richness is decreased in the long-term.
Coulson, J.C. & Butterfield, J.E.L. (1978) The animal communities of upland Britain. The future of upland Britain (ed. R.B. Tranter), pp. 417-435. Centre for Agricultural Strategy, Reading, UK.
189 The distribution and abundance of animals in uplands are influenced by altitude; there is evidence of a change in animal species composition as altitude decreases. The variety of habitat is also of crucial importance to the diversity of animals.
Coulson, J.C. & Butterfield, J.E.L. (1985) The invertebrate communities of peat and upland grasslands in the north of England and some conservation implications. Biological Conservation, 34, 197-225. Uplands are traditionally managed for sheep and/or red grouse though there is an increasing tendency to plant conifers, especially on the lower moors. This invertebrate classification relates to invertebrate communities on peat bogs and uplands in northern England and so may not apply to other areas and other grassland communities. Lower altitudes do not have a species deficit. Invertebrates influence distribution of vertebrate predators. A mosaic of wet and dry areas possesses a diverse invertebrate fauna beneficial to other species.
Coulson, J.C. & Butterfield, J. (1986) The spider communities on peat and upland grasslands in northern England. Holarctic Ecology, 9, 229-239. Spider diversity declines with an increase in altitude as does the number of species caught. This decline in number of species is due to a decrease in non-linyphiid species with increasing altitude.
Coulson, J.C., Butterfield, J.E.L. & Henderson, E. (1990) The effect of open drainage ditches on the plant and invertebrate communities of moorland and on the decomposition of peat. Journal of Applied Ecology, 27, 549- 561. Between 1970 and 1990, large areas of moorland were drained using a system of open ditches (grips), encouraged by subsidies offered under CAP. Drainage is claimed to improve land for both grouse and sheep by encouraging heather growth and removing the habitat of some invertebrate pests. However, some of these invertebrates are needed by the chicks of red grouse. This study concludes that there are few overall benefits to moor gripping, and may be disadvantageous for bird populations.
Coulson, J.C., Fielding, C.A. & Goodyer, S.A. (1992) The management of moorland areas to enhance their nature conservation interest. JNCC Report No. 134. Joint Nature Conservation Committee, Peterborough, UK. The report is concerned with upland heather heaths, blanket bog and mineral grasslands. The ecological requirements of invertebrate, bird, mammal, reptile and amphibian species are covered and the effects of habitat management on these communities considered. The effects of burning, grazing and afforestation are discussed.
Countryside Commission. (1984) A better future for the Uplands. Countryside Commission, Cheltenham, UK. Report based on a consultation exercise that began in 1983. The policies and their impact on upland areas are examined, and recommendations for future policy made.
Countryside Commission. (1991) Landscape changes in National Parks come under scrutiny. News Release, 12 December 1991. Countryside Commission, Cheltenham, UK. News release summarising the results of the first-ever survey of how the landscape has been changing in eleven National Parks. There has been a general trend towards more intensive land management, with an increase in the total area of cultivated land, improved pasture and coniferous forest and a decrease in semi-natural areas such as heath and moor. A decline in traditional features such as hedgerows and walls was also found. Summaries for each individual National Park are given.
Countryside Council For Wales. (1996) Butterflies in Wales. Countryside Council for Wales, Gwynedd, UK. Wales has 40 resident species of butterfly and three migrant species. Many species that are declining in Britain remain widespread in Wales, especially the fritillaries.
Countryside Council For Wales. (1998) Tir Gofal. Agri-environment scheme for Wales. Countryside Council for Wales, Gwynedd, UK. Summary of the new agri-environment scheme for Wales.
Countryside Council For Wales. (2000) Vision Statement. Countryside Council For Wales, Gwynedd, UK. This consultation sets out the aims for the next ten years in order to achieve a significant improvement in the natural environment of Wales.
Countryside Council For Wales. (2001) Results of internet search. http://www.ccw.gov.uk Review of work carried out by Countryside Council For Wales and summaries of reports.
190 Cowdy, A.P.M. (1997) Poster presentation: Management of semi-natural rough grazing in the Cambrian Mountains Environmentally Sensitive Area. Grassland management in ESAs. BGS Occasional Symposium No. 32 (ed R.D. Sheldrick), pp. 218-219. British Grassland Society, Reading, UK. One of the objectives of the ESA is to encourage farmers to protect semi-natural rough grazing. Agricultural improvement is prohibited and grazing levels, winter feeding and the use of pesticides are controlled.
Curtis, D.J., Bignal, E.M., Drewitt, A., Moos, C.J. & Wilson, M.J. (1991) Agricultural use, vegetation and bird assemblages in low intensity agricultural land in northern England. Birds and pastoral agriculture in Europe.- Proceedings of the 2nd European forum on birds and pastoralism, 26-30 October 1990 (eds. D.J. Curtis, E.M. Bignal & M.A. Curtis), pp. 80-91 Published on behalf of the Scottish Chough Study Group by JNCC, Peterborough, UK.
Dare, P.J. (1986) Raven Corvus corax populations in two upland regions of north Wales. Bird Study, 33,179- 189. Increase in sheep grazing has led to an improvement of food supply and thus an increase in population. As pasture is enclosed, better husbandry leads to less carrion.
Dartmoor Biodiversity Steering Group. (2001) Action for Wildlife. The Dartmoor Biodiversity Action Plan. Dartmoor National Park Authority, Newton Abbot, Devon, UK.
Dartmoor National Park Authority. (2002) Dartmoor Fact Sheets: Habitats of Dartmoor. http://www.dartmoor-npa.gov.uk Maps of the major habitats of Dartmoor and their associated environmental conditions, and plant and animal communities.
Davies, H. (1967) Influence of soil and management on the botanical composition of 20-years-old reclaimed hill pastures in mid-Wales. Journal of the British Grassland Society, 22, 141-147 Hill pastures are reclaimed by ploughing and sowing. On ill-drained soils, swards become infested with Juncus effusus. In well-drained soils, reversion is prevented by grazing. After 20 years, the pastures exhibited a very wide botanical range.
Davis, P. (1993) The red kite in Wales: setting the record straight. British Birds, 86, 295-298. The lowest numbers of kites in Wales occurred in 1930s. A brief history of the population is given.
Davis, P.E. & Newton, I. (1981) Population and breeding of red kites in Wales over a 30-year period. Journal of Animal Ecology, 50, 759-772. Kites nest in woods but forage over farmland or sheepwalk. A period of reduced mortality corresponds with afforestation in mid-Wales, possibly due to a greater availability of voles as prey and a reduction of use of poisoned baits.
DEFRA. (2001a) An overview of agricultural policy. http://www.defra.gov.uk/farm/ag2000.htm Government’s long term policy is to secure a more competitive and sustainable industry with a stronger market orientation. On 23 November 2000, the Minister, Nick Brown announced three government/industry task forces, one of which was the Hills Task Force. The report was published on 9 March 2001.
DEFRA. (2001b) Task Force for the Hills. http://www.defra.gov.uk/farm/hillsrep/report.pdf The report identifies ways English hill farmers can develop a sustainable business enterprise that contributes to the upland economy, society and environment. A brief description of current upland policies is given, plus a series of recommendations for the future.
DEFRA. (2001c) Impact of the transition from headage-based HLCA to area-based hill farm allowances (HFA) in England. http://www.defra.gov.uk A summary of the impacts resulting from a change from HLCA to HFA, and changes in the budget allocations. These changes will affect stocking densities and thus grazing pressure in the hills.
DEFRA. (2001d) The Countryside Stewardship Scheme. Traditional farming in the modern environment. Department for Environment, Food and Rural Affairs, London, UK. Summary of the Countryside Stewardship Scheme, it’s history and development and the landscape types and features the scheme aims to protect.
191 Dixon, J. (1984) The impact of agricultural change in the ecology of the Welsh uplands. PhD thesis, The University College of Wales, Aberystwyth, UK. Thesis examining the Welsh uplands: flora, fauna, agriculture and agricultural policies, moorland loss and the effects of agricultural changes.
Dixon, J.B. (1987) Ecology and management of improved, unimproved and reverted hill grasslands in mid- Wales. Agriculture and conservation in the hills and uplands (eds. M. Bell & R.G.H. Bunce), pp. 32-37. Institute of Terrestrial Ecology, Cumbria, UK. The ‘ffriddlands’ occur on the slopes of the Cambrian Mountains of Wales. In the post-war period, forestry plantations were the most significant land improvement , but since the 1970s, agricultural reclamation has occurred more rapidly, at a rate higher than in other upland areas of the UK. A high degree of reversion from improved grassland to rough grassland has been recorded. The ecology and management options of the ffriddlands are discussed.
Dixon, J.B. (1988) Comparison of agriculture and conservation in the uplands of New Zealand and Wales. Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 345-353. Blackwell Scientific Publications, Oxford, UK. Welsh habitat has been lost or modified because of farming practices, principally for sheep, encouraged by financial incentives. Diagram shows changes in vegetation with increasing altitude.
Donaldson, R.B. (1988) Annex 8: Forestry and bracken in Wales. Bracken in Wales. The Senior Technical Officer’s Group, Wales, pp. 73-80. Nature Conservancy Council, Bangor, UK. Bracken is spreading into marginal agricultural land which would be suitable for tree growth. A reversion of bracken-infested areas to woodland might be a viable method of bracken control, and increased afforestation on marginal land resulting from a reduction in agriculture could reduce bracken encroachment.
Drewitt, A. (1991) The vegetation of the Yorkshire Dales National Park. Yorkshire Dales National Park Committee, Skipton, North Yorkshire, UK. The report details the findings of a vegetation survey carried out over four years in order to provide information on the botanical interest, extent and distribution of all habitats within the National Park. A total of 41 habitats and land use categories were identified. Three main grassland types covered 58% of the area surveyed and the moorland categories, about 30%. Woodland covers only 3.6% and three-quarters of this is plantation. The diversity of habitats is a result of a long history of farming and the vegetation is continuing to change as traditional farming methods are replaced.
Duffey E. (1962) A population study of spiders in limestone grassland. Description of study area, sampling methods and population characteristics. Journal of Animal Ecology, 31, 571-599.
Eadie, J. (1984) Trends in agricultural land use: the hills and uplands. Agriculture and the Environment. ITE symposium No. 13 (ed. D. Jenkins), pp. 13-20. Institute of Terrestrial Ecology, Cambridge, UK. Hill and upland agriculture has changed since the Second World War, with fewer people being employed on a reduced number of farm holdings. A large area of semi-natural vegetation has been afforested or taken out of pasture for improvement.
Edgell, J., Smith, D. & Taylor, J. (1993) Agricultural policy in the uplands: the move to extensification. RSPB Conservation Review 7, pp. 27-34. RSPB, Sandy, Beds., UK. Agricultural policy has led to an increase in sheep numbers grazing the uplands. However, the objectives of policy in LFAs have not been met and have led to detrimental changes in the upland habitat. Extensification of sheep farming is suggested.
English Nature. (1998) UK Biodiversity Group – Tranche 2 Action Plans. Volume 1 – vertebrates and vascular plants. English Nature, Peterborough, UK.
English Nature (2001). The upland challenge. English Nature, Peterborough, UK.
English Nature & Dartmoor National Park Authority. (2001) The Nature of Dartmoor. A biodiversity profile. National Park Authority, Newton Abbott, Devon, UK.
192 Evans, R. (1977) Overgrazing and soil erosion on hill pastures with particular reference to the Peak District. Journal of the British Grassland Society, 32, 65-76. Soil erosion is taking place mainly in Agrostis-Festuca swards at the margins of bare ground. Here, this vegetation tends to support a higher sheep population. Most of the erosion scars are colonized by vegetation when sheep numbers are decreased.
Evans, S. & Felton, M. (1987) Hill livestock compensatory allowances and upland management. Agriculture and conservation in the hills and uplands. (eds. M. Bell & R.G.H. Bunce), pp. 66-72. Institute of Terrestrial Ecology, Cumbria, UK. Heather moorland is lost to afforestation, agricultural intensification and poor management, and the conservation interest of remaining areas is reduced by changes in management and grazing pressure. Since 1946, 22% of freehold rough grazing has been lost in England, 41% in Wales and 11% on Scotland. In England and Wales, higher grazing pressures may be a contributing factor. The role of Hill Livestock Compensatory Allowances is discussed.
Fitter, A.H. & Jennings, R.D. (1975) The effects of sheep grazing on the growth and survival of seedling junipers (Juniperus communis L.). Journal of Applied Ecology, 12, 637-642. The distribution of juniper has contracted in the last hundred years. Major reasons appear to have been habitat destruction by ploughing, and scrub and woodland development. Sheep grazing can also kill seedlings. Regeneration of juniper requires bare ground, usually the result of heavy grazing, for germination, and then light grazing preferably during the summer, which helps to keep surrounding vegetation down.
Flegg, J.J.M. & Glue, D.E. (1975) The nesting of the Ring Ousel. Bird Study, 22, 1-8. The ring ousel is predominantly a bird of moorland but does breed in hill farm pastures and along forestry plantation fringes. Breeding behaviour may change with an increase in pasture improvement and forestry management and a decline in the area of moorland.
Francis, I.S., Penford, N., Finch, M., Hughes, E.J. & Aitchison, J.W. (1989) Biological Survey of Common Land. No. 6: Montgomery District, Powys. Rural Surveys Research Unit, Aberystwyth, UK. Common land covers 4% of the Montgomery District, mostly in the upland parts. During 1988, 77 commons over 1 ha were surveyed. Twenty sites (17% of common land) falls within the Cambrian Mountains ESA. The majority of common land is characterised by five major habitat types: unimproved dry acidic grassland, semi- improved acidic grassland, acidic marshy grassland, bracken and blanket bog. Most commons are grazed, mainly by sheep and this, plus land improvement, presents the main threat to their conservation.
Francis, I.S., Penford, N., Finch, M., Hughes, E.J. & Aitchison, J.W. (1990) Biological Survey of Common Land. No. 7: Ceredigion District, Dyfed. Rural Surveys Research Unit, Aberystwyth, UK. Common land covers 6.8% of Ceredigion District. During 1988, 108 commons over 1 ha were surveyed. The majority of common land was characterised by four major habitat types: unimproved acid grassland, acidic marshy grassland, dry heath/acid grassland mosaic, and blanket bog. Most commons are sheep grazed and grazing pressure is high. A large proportion of the British red kite population hunts over the upland commons, which also have high densities of ravens and buzzards.
Fuller, R.J. (1982) Bird habitats in Britain, pp. 162-177. T. & A.D. Poyser, Calton, UK. Upland birds are those which utilise unimproved land that has not been enclosed within farm boundaries. Upland margins, often bracken and scrub (ffridd of Wales), are good for tree pipits, whinchat and red kite. Upper, enclosed fields, such as those found in the Pennines, are good for lapwing, oystercatcher, redshank, curlew, snipe, yellow wagtail, and golden plover. Afforestation can alter the bird species of upland. Improvement of the upland fringes can lead to bird losses.
Fuller, R.J. & Gough, S.J. (1999) Changes in sheep numbers in Britain: implications for bird populations. Biological Conservation, 91, 73-89. Grazing can affect bird populations through the loss of preferred vegetation types, alteration of food supplies and alteration of predation pressure.
Fuller, R.J., Ward, E., Hird, D. & Brown, A.F. (2002) Declines of ground-nesting birds in two areas of upland farmland in the south Pennines of England. Bird Study, 49,146-152.
193 Game Conservancy Trust. (1998) Upland partridges and sawflies. The Game Conservancy Review of 1997, pp. 21-23. The Game Conservancy Trust, Fordingbridge, UK. Grey partridges are found on grass and moorland edges of upland farms, along with skylark, lapwing, redshank and snipe, all of which have declined on lowland farms. Upland farms have not been modified as much as lowland farms. However, breeding success may be affected by weather.
Garnett, M.C. (1988) Song bird communities of the Ffridd in Wales. RSPB, Sandy, Beds., UK. Ffridd is defined as the first enclosed land coming down from the mountain. Agricultural development of ffridd is damaging to landscape and also birds. There is also concern for the future from afforestation. Songbird communities lie on an ecocline with a species-poor community on open moorland with few trees, and species- rich communities where there are more trees.
Garnett, M.C., MacFadzean, S. & Townsend, M. (1988) The foraging ecology of the whinchat (Saxicola rubetra) in Wales. In preparation. RSPB, Sandy, Beds., UK. Moorland edge habitats (ffridd) is often dominated by bracken with a range of scrub cover. Only three songbird species, yellowhammer, tree pipit and whinchat are associated with bracken slopes that have little or no scrub cover. The Welsh ffridd is the stronghold for whinchat which has undergone a range contraction elsewhere in Britain. Open stands of bracken with patches of grass provide the best habitat for foraging.
Geary, S. (2000) Dartmoor moorland breeding bird survey 2000. Unpublished report to Dartmoor National Park Authority. Breeding birds of Dartmoor moorland were last surveyed in 1979. The survey in 2000 will provide information to guide planning and management agreements. The results show that Dartmoor moorland is an internationally important site for stonechat and probably whinchat and meadow pipit. The moorland fringe and bracken habitats are particularly important for cuckoo, skylark, tree pipit, redstart, whinchat, linnet and yellowhammer.
Gerrard, A.J. (1982) Surveys of Moorland and Roughland Change No. 13. Soil characteristics of reverted farmland. A pilot study from Dartmoor. University of Birmingham, Birmingham, UK. The moorland edge has fluctuated due to conversion to farmland and reversion back to moorland. On Dartmoor, 11.3% of rough pasture is regenerated moorland and about 4.8% reverted back to moorland prior to 1885. Long-lasting changes to the soil include increased drainage, the ironpan destroyed and organic matter more evenly distributed with depth. These changes could be important for future reclamation.
Gilbert, O.L. (1980) Juniper in Upper Teesdale. Journal of Ecology, 68, 1013-1024. About 100 ha of juniper scrub occur in Upper Teesdale, mainly close to farms and on uneven ground. Past mining and farming, which resulted in a fluctuating grazing regime, produced good conditions for juniper spread in the past. Reducing grazing does not appear to encourage spread, though burning is a possibility.
Good, J.E.G. (1995) Enhancement of upland scrub in Welsh ESAs. MAFF/NERC Contract BD0406. Institute of Terrestrial Ecology, Gwynedd, UK. Scrub, often dominated by hawthorn, is widespread on medium altitude semi-natural grazing land.. Scrub regeneration is inversely proportional to sheep grazing pressure and current grazing levels are too high to allow regeneration. There is a strong positive correlation between the occurrence of hawthorn and bracken.
Good, J.E.G, Bryant, R. & Carlill, P. (1990) Distribution, longevity and survival of upland hawthorn (Crataegus monogyna) scrub in North Wales in relation to sheep grazing. Journal of Applied Ecology, 27, 272- 283. Hawthorn stands are widespread on steep valley sides and consist of scattered bushes. Increasing sheep numbers are preventing or reducing seedling establishment, which could pose long term conservation problems.
Good, J.E.G., Norris, D.A. & Daniels, A. (1995) ESA research on upland scrub in Wales. Annual Report 1995. Institute of Terrestrial Ecology, Bangor, UK. Scrub, often dominated by hawthorn, is a characteristic component of semi-natural upland grazing land. It has a high landscape and wildlife value. In the Radnor ESA and Cambrian Mountains ESA there has been little regeneration of hawthorn scrub and there is a close negative correlation between sheep numbers and hawthorn regeneration. There is a strong positive association between mature hawthorn scrub and bracken.
Good, J.E.G., Norris, D., McNally, S. & Radford, G.L. (1997) Developing new native woodland in the English uplands. No. 230 - English Nature Research Reports. English Nature, Peterborough.
194 An investigation of the possibilities for the expansion of native woodland in the English uplands, particularly in the National Parks. Potential conflicts are explored.
Goodier, R. (1985) Nature conservation in the hills. BCPC Mono. No. 30. Vegetation management in northern Britain (ed. R.B. Murray), pp. 55-70. British Crop Protection Council, UK. Definitions of upland and land class descriptions. The paper details habitat change in the uplands, both gradual and radical.
Graham, K. & Dalton, A. (1993) Broadleaved woodland in the Yorkshire Dales National Park. Final Report (1990-1993). Yorkshire Dales National Park, Grassington, UK. The Yorkshire Dales National Park covers 1760 sq. kms. of which 0.9% is semi-natural broadleaved woodland. Many woods are small and very few are actively managed. Regeneration is confined to inaccessible slopes which inhibit grazing pressure. Eighteen NVC woodland communities have been recorded; a brief description of each is given.
Grant, M. (1993) Curlew. The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991 (eds. D.W. Gibbons, J.B. Reid & R.A. Chapman), pp. 184-185. T. & A.D. Poyser, London, UK. Presents distribution and density maps of breeding curlew in Britain and Ireland.
Green, B.H. (1984) Landscape Conservation in Agriculturally Less Favoured Areas. Occasional Paper No. 13, December 1984. Report of a seminar organised by the Countryside Commission at the Centre for European Agricultural Studies, Wye College, University of London, 4-6 July, 1983. Wye College, Ashford, UK. Agricultural support in Less Favoured Areas ensures the continuation of farming in the uplands. Improvement of land is seen as vital but can have an adverse environmental impact. Sixty percent of the LFAs in Britain are in National Parks. However, money spent in the LFAs represents only a small part of the CAP budget - c. 1%. Conservation management agreements to compensate the farmer for not undertaking grant-aided agricultural improvement, do not always prevent loss of important habitats, such as hay meadows and moorlands. A management scheme to make conservation an integral part of farming practice has been introduced in the Peak District National Park.
Green, M.J., Harris, A.D. & Williams, I.T. (1994) Breeding waders in Wales 1993. Interim Report. Unpublished report. RSPB, Sandy, Beds., UK. The lapwing population has halved since the late 1980s and breeding densities are very low. Declines of curlew had already been noted in the mid 1980s, mainly due to afforestation. Numbers have continued to decrease. Snipe have probably declined due to the loss of favoured habitat to agricultural intensification. Much of the Welsh countryside is now unsuitable for breeding waders.
Gregory, R.D., Wilkinson, N.I., Noble, D.G., Robinson, J.A., Brown, A.F., Hughes, J., Procter, D., Gibbons, D.W. and Galbraith, C.A. (2002) The population status of birds in the United Kingdom, Channel Islands and Isle of Man: an analysis of conservation concern 2002-2007. British Birds, 95, 410-448.
Griffiths, J.B., Henman, D., Jones, D.L., Wildig, J., Rushton, S.P. & Sanderson, R. (1997) Poster presentation: Stocking rate comparisons on semi-natural rough grazings in the Cambrian Mountains. Grassland management in ESAs. BGS Occasional Symposium No. 32 (ed. R.D. Sheldrick), pp. 232-233. British Grassland Society, Reading, UK. Summary of a comparison of stocking rates in ESA Tier 1 and Tier 2, and the effects on vegetation.
Grove, S.J, Hope Jones, P., Malkinson, A.R., Thomas, D.H. & Williams, I. (1988) Black grouse in Wales, spring 1986. British Birds, 81, 2-9. Since the mid 1970s, the Welsh population of black grouse has been in decline. Changes in land use, especially loss of heather and bilberry to grassland, heavier grazing pressure and large-scale forestry may all have affected their current status.
Hale, W.G.H., & Cotton, D.E. (1993) Vegetation changes on Ilkley Moor between 1964 and 1984, and possible environmental causes. Naturalist, 118, 123-134. Vegetation has changed with bracken becoming widespread on the lower slopes but has not yet extended onto the upper moor. Locally, grasses and rushes have become more abundant and crowberry has declined in the lowest areas.
195 Harding, N.J., Green, R.E. & Summers, R.W. (1994) The effects of future changes in land use on upland birds in Britain. Unpublished report. RSPB, Edinburgh, UK. Although mainly containing examples from Scotland, the report describes current land use in the uplands. It attempts to predict the effect of future changes in land use and moorland management, primarily burning, grazing and afforestation, will have on the upland bird species, especially Red Data Book species.
Harkness, C.E. (1982) Surveys of Moorland and Roughland Change No. 12. Mapping changes in the extent of woodland in upland areas 1885-1975. University of Birmingham, Birmingham, UK. Results of surveys of changes in the extent and nature of woodland between 1885-1975, in the Brecon Beacons National Park and the Snowdon massif. Both areas experienced a 50% increase in the overall amount of woodland during the study period. This was almost entirely due to coniferous planting. There has been a decline in broad-leaved woodlands.
Harris, S., Morris, P., Wray, S. & Yalden, D. (1995) A Review of British Mammals: Population Estimates and Conservation Status of British Mammals other than Cetaceans. Joint Nature Conservation Committee, Peterborough, UK.
Haworth, P.F. and Fielding, A. (1988) Conservation and management implications of habitat selection in the merlin Falco columbarius L. in the south Pennines, UK. Biological Conservation, 46, 247-260. Breeding merlins are associated with areas covered by Calluna and bracken, with intensive gamekeepering, which are managed primarily for grouse. The farmland fringing the moorland is unlikely to provide enough food for merlins. Increased sheep grazing removes the Calluna which is replaced by Nardus and Molinia and merlin numbers decline. Human disturbance also adversely affects merlin.
Haworth, P.F. & Thompson, D.B.A. (1990) Factors associated with the breeding distribution of upland birds in the south Pennines, England. Journal of Applied Ecology, 27, 562-577. The upland margin is defined as being of moderate relief with steep slopes and a high density of habitation and high intensity of agricultural use. The habitat preferences of birds are discussed, especially of waders and passerines which use fields for feeding. Reduced grazing could encourage scrub development and more passerines.
Hayes, M.J., Jones, A.T., Sackville Hamilton, N.R., Wildig, J. & Buse, A. (2001) Studies on the restoration of Welsh hedges. Hedgerows of the World: their ecological functions in different landscapes (eds. C. Barr & S. Petit), pp. 339-348. IALE (UK), Aberdeen, UK. Hedgerows in the Welsh countryside have suffered loss and neglect over recent decades, particularly in the semi-upland areas. Hedgerow restoration and re-planting is now a high priority in Welsh agri-environment schemes. Key factors involved in re-establishing hedges in these areas are discussed.
Hayes, M.J., Sackville Hamilton, N.R., Tallowin, J.R.B., Buse, A. & Davies, O. (2000a) Methods of enhancing diversity in upland swards. Final report to MAFF, April 2000. MAFF Project Code: BD1424. Institute of Grassland and Environmental Research, Aberystwyth, UK. Increases in the extent of intensive livestock farming in the hills and uplands of western Britain have led to the dominance of largely species-poor pastures with little conservation value. There is an urgent need for restoration of semi-natural grassland communities. The report details a study to identify management for accelerating natural colonisation, assess associated wildlife benefits and evaluate production implications for the farmer.
Hayes, M.J., Sackville Hamilton, N.R., Tallowin, J.R.B., Buse, A. & Davies, O. (2000b) Welsh ESA field- margins and hedges. Final report to MAFF, April 2000. MAFF Project Code: BD1605. Institute of Grassland and Environmental Research, Aberystwyth, UK. Hedges and their field margins are an important landscape feature in Wales, where they contribute towards plant and animal diversity. Restoration and re-planting is an important component of Welsh agri-environment schemes. Much of this is done with hawthorn, often of foreign stock, which could have important ecological consequences. The use of a wider selection of native trees and shrubs would benefit both birds and invertebrates.
Helliwell, D.R. (1986) Bracken clearance and potential for afforestation. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 459-464. Parthenon Publishing, Lancaster, UK.
196 Bracken tends to grow on land where there is the potential for tree growth. Trees would encourage a greater diversity of animal and plant species, and as long as care is taken with the planting, the landscape value and access to the site would not be adversely affected. Woodlands can diversify the economic basis of a farm and may be particularly important on steep, inaccessible land that currently is contributing little to the farm economy.
Heppingstall, K., Penford, N., Aitchison, J.W. & Masters, S. (1990) Biological Survey of Common Land No. 17: Cleveland. Rural Surveys Research Unit, Aberystwyth, UK. Common land covers about 0.5% of the county area. Eighty-four percent of this common land is characterised by three major habitat types: acidic dry dwarf shrub heath, bracken, and marshy grassland. None of the surveyed commons showed signs of agricultural improvement, though all were managed to some extent.
Hester, A.J. (1996) Overgrazing in upland habitats: a literature review. Contract report FC73-01-133 for Countryside Council for Wales. Macaulay Research and Consultancy Services Ltd., Aberdeen, UK. Sheep are the main grazers in Wales. Past vegetation changes and current vegetation are described. Heather has declined while grassland and bracken have increased.
Hester, A.J. & Miller, G.R. (1995) Scrub and woodland regeneration prospects for the future. Heaths and moorland: cultural landscapes (eds D.B.A. Thompson, A.J. Hester & M.B. Usher), pp. 140-153. HMSO, Edinburgh, UK. Scrub and woodland are an important part of the mosaic of upland plant communities. Referring primarily to Scotland, this paper describes the factors affecting scrub and woodland regeneration. Grazing is probably the most important factor. The Less Favoured Areas system probably has a detrimental effect on regeneration by encouraging overgrazing.
Hetherington, S.L. & Anderson, J.M. (1998) Lignin signatures show the effects of changes in heather and bracken cover on the composition of organic matter in moorland soil profile. Oecologia, 117, 194-200. Bracken is displacing heather on many moorlands in Britain; it has doubled its area in the United Kingdom over the last 30 years. This rapid expansion appears to be a result of changing upland pasture management, increasing nutrient deposition in rainfall and widespread drainage of moorland. Bracken can be controlled, but to prevent re-encroachment, soil conditions encouraging a moorland community have to be re-established.
Higgs, G. & Bracken, I. (1990) Statutory designation and land-use changes - a case study from mid-Wales. Journal of Rural Studies, 6 (3), 279-290. There has been a lack of continuous records of land-use change in Britain and levels of precision in the collection of data vary. Currently there is no comprehensive method by which to evaluate rates of land use change. This project compares land use derived from aerial photograph interpretations to identify changes in broad land use types and the influence of various statutory designations.
Hill, D. (1993) Ring Ouzel. The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991 (eds. D.W. Gibbons, J.B. Reid & R.A. Chapman), pp. 312-313. T. & A.D. Poyser, London, UK. Presents distribution and density maps of breeding ring ouzel in Britain and Ireland.
Hill, M.O. (1979) TWINSPAN - a FORTRAN program for arranging multivariate data in an ordered two-way table by classification of the individuals and attributes. Section of Ecology & Systematics, Cornell University, Ithaca, New York.
Hill, M.O., Evans, D.F. & Bell, S.A. (1992) Long-term effects of excluding sheep from hill pastures in North Wales. Journal of Ecology, 80, 1-13. Description of vegetation changes in hill pastures. Successional changes depend upon soil and initial vegetation. Early changes occur rapidly but there are few long-term changes in the herbaceous vegetation. There is almost no invasion of new species. Voles become the dominant herbivore.
Hill, M.O. & Jones, E.W. (1978) Vegetation changes resulting from afforestation of rough grazings in Caeo Forest, South Wales. Journal of Ecology, 66, 433-456. Caeo Forest was planted between 1931 and 1941, and vegetation was monitored in 1944 and 1976. In 1944, ground vegetation still could be related to the past land use of pasture. In 1976, herbs had declined. Calluna and Pteridium aquilinum had almost disappeared. Grass species increased after crop thinning.
197 Hinsley, S.A., Davies, C.E., Ferns, P.N. & Bellamy, P.E. (1999) Review of bird species and habitat interactions in Welsh terrestrial lowland environments. CCW Contract Science Report No. 343, pp. 31-33. CCW, UK. Ffridd is the zone between the fields of the valleys and the unenclosed hill land above. It includes areas of bracken, gorse, heather, grassland and scrub. Results of a RSPB investigation of habitat and songbird communities are given.
Hobson, P. (1985) A study of the bird community of ffriddland in mid-Wales (1985). RSPB Wales Office, Newtown, Powys, UK. Ffriddland is defined as the zone of bracken-dominated marginal land on hillsides. The bird community is made up of open-ground and scrub-loving species, but the numbers and distribution are affected by the degree of scrub cover and the nature of the ground vegetation. Bird numbers and diversity are smaller on improved grassland than on unimproved grassland.
Holloway, S.M. (1995) The control of bracken on the North York Moors National Park with specific reference to the rhizome system. Bracken: an environmental issue. International Bracken Group Special Publication No. 2 (eds. R.T. Smith & J.A. Taylor), pp. 148-159. University of Wales, Aberystwyth, UK. Bracken covers most of the surrounding slopes of the North York Moors National Park and competes with the heather by encroachment onto the moor. This is detrimental to the grouse population and increases the stocking rate of sheep onto the heather areas, possibly resulting in overgrazing. In 1988, approximately 28% of the total moor area was encroached by bracken, so an integrated five year control programme was launched. The study of bracken on the Moors shows that the growth cycle of bracken is an important factor in determining the success of control using asulam.
Holmes, P.R., Boyce, D.C. & Reed, D.K. (1993) The ground beetle (Coleoptera: Carabidae) fauna of Welsh peatland biotopes: factors influencing the distribution of ground beetles and conservation implications. Biological Conservation, 63, 153-161. The distribution of carabid beetles is influenced by four factors: nutrient status, soil saturation, altitude and grazing. Light grazing appears to have little influence on the carabid guilds present. Grazing is frequently used as a management technique, and this can affect vegetation structure as well as species structure. A mosaic of habitats is best both floristically and for invertebrates.
Holmes, W. (1989) Hill and upland grazing. Grass. It’s production and utilization, (ed. W. Holmes), pp. 169- 171. Blackwell Scientific Publications, Oxford, UK. Brief description of sheep grazing in uplands.
Hopkins, A. & Wainwright, J. (1989) Changes in botanical composition and agricultural management of enclosed grassland in upland areas of England and Wales, 1970-86, and some conservation implications. Biological Conservation, 47, 219-235. Over 15 years, the area of sown grass increased and 77% of grassland received inorganic fertilizer. Agricultural improvements led to major changes in botanical composition.
Hopkins, A., Wainwright, J., Murray, P.J., Bowling, P.J. & Webb, M. (1988) 1986 survey of upland grassland in England and Wales: changes in age structure and botanical composition since 1970-72 in relation to grassland management and physical features. Grass and Forage Science, 43, 185-198. The paper details a survey of enclosed upland areas. Over 15 years there has been an increase in Lolium, but there is still a large area of relatively unimproved grassland which receives little fertilizer and has not been reseeded.
Hornung, M. (1984) The impact of upland pasture improvement on solute outputs in surface waters. Agriculture and the Environment. ITE symposium No.13 (ed. D. Jenkins), pp. 150-155. Institute of Terrestrial Ecology, Cambridge, UK. Pasture improvement involves the addition of lime and fertilizers. Their loss to drainage waters plus an increase in solute outputs due to changed soil conditions may cause changes in otherwise unpolluted streams.
Horsefield, D. & Thompson, D.B.A. (1993) The Northern Pennines. The Evaluation of Upland Habitats. English Nature Research Reports No. 64. English Nature, Peterborough, UK. The report provides an overview of a vegetation survey of 12 upland blocks in the northern Pennines. The extensive dwarf-shrub heaths and blanket mire are of high nature conservation value. Management and land-use information were also collected.
198 Hudson, P. (1989) Black grouse in Britain. The Game Conservancy Review of 1988, pp. 119-124. The Game Conservancy, Fordingbridge, UK. The extent of the black grouse population in Britain and Europe is discussed. The causes of their decline include loss of habitat, loss of invertebrate food, and increased predation.
Hudson, P. & Newborn, D. (1989a) The conservation of heather moorlands. The Game Conservancy Review of 1988, pp. 111-117. The Game Conservancy, Fordingbridge, UK. In 1988, it was announced that new conservation grants would be introduced in 1989 to encourage the regeneration of heather moors. Heather loss has occurred mainly due to overgrazing due to an increase in sheep numbers in the uplands. In conjunction with this, there has been a loss of grazing habitats due to forestry and an increase in unpalatable feed such as bracken.
Hudson, P. & Newborn, D. (1989b) The environmental impact of bracken. The Game Conservancy Review of 1988, pp. 117-119. The Game Conservancy, Fordingbridge, UK. Bracken is one of the most successful weeds in the British Isles and is currently spreading at the rate of 1-4% per annum. The plant tends to favour areas of acidic grassland and is common on the steep sides of moorland hills. It is of low conservation value with only 15 species of birds breeding in bracken and a low abundance of invertebrate groups.
Hudson, P.J. (1988) Spatial variations, patterns and management options in upland bird communities. Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 381-397. Blackwell Scientific Publications, Oxford, UK. Homogenous habitats have a lower bird species composition. If the habitat is more complex with more woodland and rough grassland, a new range of bird species is introduced.
Hudson, P.J. & Baines, D.J. (1993) Black Grouse. The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991 (eds. D.W. Gibbons, J.B. Reid & R.A. Chapman), pp. 130-131. T. & A.D. Poyser, London, UK. Presents distribution and density maps of breeding black grouse in Britain and Ireland.
Hughes, E.J. & Aitchison, J.W. (1986) Bracken and the common lands of Wales. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 93-99. Parthenon Publishing, Lancaster, UK. In 1958, it was estimated that approximately 4% of the total land area of England and Wales was classed as common land. These commons are covered by extensive tracts of bracken. The rights of estovers and the need to halt the encroachment of bracken onto the common lands of Wales are discussed.
Hughes, R.E., Dale, J., Williams, I.E. & Rees, D.I. (1973) Studies in sheep population and environment in the mountains of north-west Wales. I. The status of the sheep in the mountains of North Wales since Mediaeval times. Journal of Applied Ecology, 10, 113-132. The grazing of sheep in the uplands probably started in the 12th century. The growth of sheep and cattle grazing and the numbers of livestock present from the twelfth century to the present day, are discussed. Sheep have always been more abundant than cattle. Long term trends and short-term fluctuations in stocking densities, and changes in husbandry relating to seasonal patterns of grazing, may be important in relation to vegetation changes in the area.
Hughes, R.E., Dale, J., Mountford, M.D. & Williams, I.E. (1975) Studies in sheep populations and environment in the mountains of north-west Wales. II. Contemporary distribution of sheep populations and environment. Journal of Applied Ecology, 12, 165-178. A continuation of an earlier study, this work shows that summer population densities of sheep in Snowdonia varied greatly, with the highest populations occurring on land affected by man from an early period. Ecological features such as rainfall, soil acidity, altitude and vegetation all influence sheep distribution.
Hutchinson, K. (2001) Survey of ring ouzel territories in the North York Moors National Park. Moorland Research Review 1995-2000 (eds. R. Charles, S. Wightman & M. Hammond), pp. 85-88. North York Moors National Park Authority, Helmsley, UK Describes surveys of breeding ring ouzels on the North York Moors and provides notes on habitat use.
Institute of Terrestrial Ecology. (1978) Upland land use in England and Wales. Countryside Commission, Cheltenham, UK.
199 Results of a desk study giving general information on the uplands: general characteristics, agriculture, woodlands and forestry, common land, vegetation, plus a regional study of Cumbria.
Jardine, D.C. & Reid, J.B. (1994) Twite. The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991 (eds. D.W. Gibbons, J.B. Reid & R.A. Chapman), pp. 418-419. T. & A.D. Poyser, London, UK. Presents distribution and density maps of breeding twite in Britain and Ireland.
Jenkins, D. & Watson, A. (2001) Bird numbers in relation to grazing on a grouse moor from 1957-61 to 1988- 98. Bird Study, 48, 18-22. Changes in vegetation from ling to grass, as a result of grazing, can affect bird numbers. These changes tend to occur on moorland near farms. In this study, oystercatcher, lapwing and curlew increased where smooth grass replaced ling. Golden plover declined though this was probably due to severe winter weather. Grey partridge, red and black grouse all disappeared from heavily grazed moor. Both grouse species remained on lightly grazed ground.
Jerram, R., Clayden, D. & Rees, S. (1998) North York Moors National Park Upland Vegetation Survey. English Nature Research Reports No. 245. English Nature, Peterborough, UK. The North York Moors holds one of the largest continuous tracts of heather moor in England and Wales. Dry heath represents the greatest vegetation type, followed by wet heath, bracken, mires and acid grassland. The report gives an overview of moorland vegetation throughout the National Park.
Jerram, R. & Drewitt, A. (1998) Assessing Vegetation Condition in the English Uplands. English Nature Research Reports No. 264. English Nature, Peterborough, UK. The results of a project to develop a method for assessing the condition of semi-natural vegetation in the English uplands. The effects of current upland management practices and other environmental factors which affect vegetation conditions are discussed.
Johnson, J., Hardwick, N.V. & Kitchen, R. (1995) Management of a heather/bracken interface for the long- term control of bracken and regeneration of heather. Bracken: an environmental issue. International Bracken Group Special Publication No. 2 (eds. R.T. Smith & J.A. Taylor), pp. 197-198. University of Wales, Aberystwyth, UK. Bracken encroachment is a particular problem in the North York Moors National Park, where it invades the lower lying grassland and extends into the heather on the moor. Comparison of a number of management techniques indicated that spraying with herbicide led to the greatest reduction in bracken biomass and a significant increase in the ground cover of other vegetation.
Jones, A.T., Hayes, M.J. & Sackville Hamilton, N.R. (2001) The effect of provenance on the performance of Crataegus monogyna in hedges. Journal of Applied Ecology, 38, 952-962. Widespread planting of new hedges is encouraged. However, much of the planted material, particularly of hawthorn, has been obtained from Europe. This study suggests that for greater establishment success and for greater environmental benefits, there should be a close matching of hawthorn provenance to planting site.
Jones, W.D. (1984) Hill sheep and farming in Wales - economic and social aspects. Hill Land Symposium (ed. M.A. O’Toole), pp. 478-494. Ballinrobe, Eire. Agriculture in the hills and uplands contributes 25-30% of the Welsh agricultural output (1984), and below 5% in England. In Wales, about 20% of the rough grazings have been improved in post war years; a larger area is still improvable though it will be poorer quality, less easily worked and more costly to improve. The main factors affecting hill sheep farming are discussed.
Kahrom, E. & Edington, J.M. (1983) A comparison of bird populations on improved and unimproved upland grazing land at the Pwllpeiran Experimental Husbandry Farm, mid-Wales. Unpublished report. University of Wales, Cardiff, UK. A study into how upland agricultural improvement might affect bird populations. The improved land had been reseeded, limed and fertilised, and had higher grazing levels, while the unimproved land was rough moorland grazing. Red grouse made no use of improved land. Both skylark and meadow pipit had fewer territories on the improved plot, though those that nested on the unimproved land used the improved areas for collecting food. Curlews also bred on the unimproved plot but used the improved land for feeding. Flock feeding species: crow, rook, raven, starling and woodpigeon, avoided all unimproved land.
200 Keiller, S.W., Buse, A. & Cherrett, J.M. (1995) Effects of sheep grazing on upland arthropods in Snowdonia and Mid-Wales. CCW Contract Science Report No. 120. Institute of Terrestrial Ecology, Gwynedd, UK. In Wales, 60% of the land lies over 300m above sea-level. The grazing of livestock, particularly sheep, has been the main form of land-use since medieval times. Heather cover has declined, to be replaced by grasses in many areas. A reduction or withdrawal of grazing will lead to an increase in the diversity and abundance of spiders of podsolic soils, as the vegetation once again becomes dominated by heathland species. Those carabid and spider species associated with heathland and undisturbed habitats will benefit. This could favour bird species.
Kelly, P.G. & Perry, K.A. (1990) Research and survey in nature conservation No. 30. Wildlife habitat in Cumbria. Nature Conservancy Council, Peterborough, UK.
King, M. (2001) Any room for scrub? Ecos, 22 (2), 21-24. Over the last 20 years, the CAP has encouraged an increase in sheep numbers on the fells at the expense of other habitats, particularly upland dwarf shrub heath, upland scrub and upland woodland. A mosaic of habitats has been replaced by species poor acid grassland. The recent foot and mouth outbreak has reduced sheep numbers and could encourage a change to low intensity grazing. The regeneration of dwarf shrub heath and juniper scrub should be encouraged.
Knight, A.C. & Shepherd, K.B. (1986) The effect of agricultural improvement on some upland breeding birds in Wales. Nature in Wales, 5 (1-2), 12-18. Comparison of breeding bird populations on unimproved and improved land. Improved land had less nesting cover, and fewer invertebrates for meadow pipits. Skylarks preferred improved land. Agricultural improvements were detrimental to red grouse.
Lance, A.N. (1978) Upland wildlife: some future conservation problems. The future of upland Britain (ed. R.B. Tranter), pp. 448-460. Centre for Agricultural Strategy, Reading, UK. The reclamation of moorland into in-bye land increases stocking densities, but has a detrimental effect on upland wildlife. Reclaimed land can be invaded by rushes or bracken if the land is not sited and managed carefully. Changes in EC and other grant-aid policy towards agricultural land will affect moorland reclamation in the future.
Lawton, J.H., MacGarvin, M. & Heads, P.A. (1986) The ecology of bracken-feeding insects: background for a biological control programme. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 285-292. Parthenon Publishing, Lancaster, UK. Up to 40 insects in Britain feed upon bracken, with a core group of 27 species regularly exploiting the above ground parts of the plant. Half of these feed on bracken alone. The results of a 13 year study at Skipwith Common, North Yorkshire are given.
Lee, H.C., Cooke, J.A. & Bines, T.J. (1986) The structure of a grazed upland bracken (Pteridium aquilinum L. Kuhn) community. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 205-214. Parthenon Publishing, Lancaster, UK. Established bracken in grazed upland pasture is regarded as a weed as it is associated with lower grazing potential and toxicity. This study showed that vegetation species richness and pasture grass biomass declined as bracken frond density increased.
Lindsay, I. & Waddington, M. (1995) The Welsh Grouse Project. The Game Conservancy Review of 1994, pp. 143-145. The Game Conservancy, Fordingbridge, UK. A long-term decline in grouse numbers has occurred, due to a widespread loss and deterioration of moorland caused by afforestation, agricultural reclamation, scrub and bracken invasion and overgrazing.
Little, B. & Davison, M. (1992) Merlins Falco columbarius using crow nests in Kielder Forest, Northumberland. British Birds, 39, 13-16. Prior to 1979, merlins bred mostly on the ground in heather. In 1979, the first nest was found in a crows nest along the moorland edge of a spruce plantation. This nesting habit increased and by 1990, over 50% of the population was breeding in crows’ nests in conifers. This change coincided with forest reaching an age suitable for crows to nest in.
Lovegrove, R. & Bowman, N. (Unknown) Breeding bird census in bracken areas on Ffridd land in mid-Wales. Unpublished report. RSPB, Sandy, Beds., UK.
201 Ffridd covers an extensive area in Wales and has resisted the change to improved grassland due to the steep slopes, though modern agricultural techniques has enabled many of these areas to be improved. Thirty-three breeding bird species were found on bracken covered areas of ffridd. Whinchat relied upon it as its main habitat. On improved grassland that was censused, only six species were found breeding.
Lovenbury, G.A., Waterhouse, M. & Yalden, D.W. (1978) The status of black grouse in the Peak District. Naturalist, 103, 3-14. Leks occur on improved pasture or meadow land. A decline in numbers may be due to changes in land use, such as afforestation, or greater grazing pressure leading to a loss of habitat mosaic.
Luff, M.L. & Rushton, S.P. (1988) The effects of pasture improvement on the ground beetle and spider fauna of upland grasslands. Aspects of Applied Biology, 17 (1), 67-74. Unimproved grassland generally had more diverse ground beetle and spider fauna. Improvement reduced spider diversity due to changes in vegetation. Improvements that involved soil disturbance led to the greatest reduction in ground beetles.
Luff, M.L. & Rushton, S.P. (1989) The ground beetle and spider fauna of managed and unimproved upland pasture. Agriculture, Ecosystems and Environment, 25, 195-205. Unimproved sites had more spiders and beetles of a more diverse fauna. Much variation between faunae of individual unimproved sites was found. Improved sites all had similar depleted fauna.
MacEwen, M. & Sinclair, G. (1983) New life for the hills. The Council for National Parks, London, UK. Upland areas are under threat and the present system of financial support for upland farmers has contributed to the upland decline. The report discusses present official policies and proposes changes for future policy in agriculture and forestry.
MacPherson, Rev. H. A. (1892) A Vertebrate Fauna of Lakeland. David Douglas, Edinburgh, UK. Provides notes on distribution and habitat use by breeding birds in the Lake District in the late 19th Century. Reference is made to the importance of rough grazing on the hill-edge for breeding snipe and the decline in snipe numbers was attributed to agricultural improvement following enclosure. Curlew were primarily moorland breeders but small numbers were recorded nesting in enclosed pastures on the hill-edge. It was suggested that lapwing numbers may have increased following the improvement of grassland on the hill-edge.
MAFF. (1997) Pennine Dales ESA. Guidelines for Farmers. Ministry of Agriculture, Fisheries and Food, London, UK. Farming over hundreds of years has produced a unique landscape in the Pennine Dales. They contain extensive hay meadows, important for their fauna and ground-nesting birds. The upland pastures are of national importance for breeding birds such as curlew and black grouse. The guidelines of the ESA scheme to protect this landscape are given.
MAFF. (1998) Dartmoor ESA. Guidelines for farmers. Ministry of Agriculture, Fisheries and Food, London, UK. Dartmoor is the highest and largest area of upland in southern England. Occupied and farmed for hundreds of years, the area is characterised by small fields enclosed by hedgebanks or stone walls. The guidelines of the ESA scheme to protect the landscape are given.
MAFF. (2001a) The Upland Experiment. Ministry of Agriculture, Fisheries and Food, London, UK. Report describing the progress of two projects being conducted in the Forest of Bowland, Lancashire and Bodmin Moor, Cornwall. The project was to investigate an integrated approach to sustainable rural development and the environment, and from this, draw up a mix of proposals for the English uplands.
MAFF (2001b) Task force for the hills. Ministry of Agriculture, Fisheries and Food, London, UK. The Hills Task Force was established in November 2000 with a remit to identify ways in which the Government can help English hill farmers to develop sustainable businesses. Subsidies, regulations, funding and agri- environment schemes that affect hill farmers are discussed.
Marquiss, M., Newton, I. & Ratcliffe, D.A. (1978) The decline of the raven, Corvus corax, in relation to afforestation in southern Scotland and northern England. Journal of Applied Ecology, 15, 129-144.
202 This study showed that the number of ravens breeding in southern Scotland and northern England declined significantly between the 1960s and 1974-5 and demonstrated that the desertion of nest sites was correlated primarily with afforestation of sheepwalk.
Marquiss, M., Ratcliffe, D.A. & Roxburgh, R. (1985) The numbers, breeding success and diet of golden eagles in southern Scotland in relation to changes in land use. Biological Conservation, 34, 121-140. In the early 1970s, afforestation of open country removed much of the productive foraging habitat for three of four pairs of golden eagles, that were established in south-west Scotland. The remaining open country was at a higher altitude where live prey were scarce. Animals living in conifer plantations did not form a substantial part of the diet. The birds probably benefited initially from afforestation due to greater protection from human interference, but it eventually reduced the amount of habitat suitable for eagles, leading to their decline.
Marrs, R.H., Le Duc, M.G., Mitchell, R.J., Goddard, D., Paterson, S. & Pakeman, R.J. (2000) The ecology of bracken: its role in succession and implications for control. Annals of Botany, 85 (Supplement B), 3-15. Bracken holds a mid-successional position between early-successional, semi-natural communities such as grassland, heaths and moors, and late-successional woodlands. Most bracken invasions come from rhizome invasion from adjacent land at a rate of a few metres per year. Moorland is more likely to be lost if it has not been burnt. Tree canopy can suppress bracken, but bracken inhibits the invasion of other species, either by direct shading or the presence of litter. Bracken is difficult to eradicate and may be impossible unless there is a complete change of land use.
Marrs, R.H., Pakeman, R.J., Le Duc, M.G. & Paterson, S. (1997) Bracken Invasion in Scotland. Botanical Journal of Scotland, 49 (2),347-356. Bracken is a weed problem on marginal land, despite control measures. Agricultural losses can be considerable through loss of grazing land or through increased veterinary costs. In Scotland there has been an increase in land dominated by bracken as a consequence of land use changes. Rural depopulation and reductions in the intensity of upland farming have reduced bracken management and allowed invasion into previously cultivated areas. There has been a switch from cattle to sheep which do less damage to the plant, and improved drainage which has assisted spread from better-drained areas.
Massey, M.E. (1978) The bird community of an upland nature reserve in Powys, 1970-1977. Bird Study, 25, 167-174. Describes assemblages of breeding bird species in different habitats on an upland nature reserve (Craig Cerrig- gleisiad National Nature Reserve) in the Brecon Beacons. The paper provides a valuable comparison between species assemblages on open moorland with those in hill-edge habitats (valley slopes and in scrub and woodland).
McFerran, D.M., McAdam, J.H. & Montgomery, W.I. (1995) The impact of burning and grazing on heathland plants and invertebrates in County Antrim. Biology and Environment: Proceedings of the Royal Irish Academy, 95B (1), 1-17. Burning of heather moorland initiates ‘succession pathways’ which appear to have characteristic plant and invertebrate species associations. Removal of Calluna dominance leads to a period of high plant species diversity which is affected by grazing. Calluna will not re-establish itself as the dominant species until several years after burning, even without grazing. Burning and grazing significantly affects the abundance of specific ground beetle and spider species. A mosaic of Calluna stands of varying age is essential for the conservation of invertebrate species.
McFerran, D.M., Montgomery, W.I. & McAdam, J.H. (1994) The impact of grazing on communities of ground-dwelling spiders (Araneae) in upland vegetation types. Biology and Environment: Proceedings of the Royal Irish Academy, 94B (2), 119-126. Although this work was carried out in Ireland, the results apply to the British uplands. Spider community composition and number of spiders were influenced by vegetation type and grazing regime.
McGhie, H.A., Brown, A.F., Reed, S. & Bates, S.M. (1994) Aspects of the breeding ecology of twite in the south Pennines. English Nature Research Report No. 118. English Nature, Peterborough, UK. A study of the habitat associations of twite. The birds nest on the moorland edge and feed in fields of dandelions and sorrel. The plants occur in highest densities in unimproved meadows and lowest densities in pastures and reseeds. These fields are abandoned when the vegetation is cut. Nest sites in bracken and heather are preferred. Destruction of nesting habitat by overburning, overgrazing, afforestation or agricultural
203 intensification and destruction of feeding habitat by improvement or an increase in livestock numbers, are all likely to threaten this bird species.
McKnight, A.J., O’Brien, M., Waterhouse, M. & Reed, S. (1996) Breeding birds of the North Staffordshire Moors: survey report 1996. Unpublished report. RSPB, Sandy, Beds., UK. The survey covered the same area as that of 1985 and 1992. It showed a decline in bird populations due to agricultural intensification: drainage, increased grazing and conversion of hay meadows to silage fields. The species which rely on wet ground and hay meadows for feeding and nesting have suffered the greatest declines.
McVean, D.N. & Ratcliffe, D.A. (1962) Plant communities of the Scottish Highlands. Monographs of the Nature Conservancy No. 1. HMSO, London, UK. Describes zonation of upland vegetation in Scottish Highlands in relation to altitude, including location of natural tree line.
Meek, E.R., Rebecca, G.W., Ribbands, B. & Fairclough, K. (1998) Orkney hen harriers: a major population decline in the absence of persecution. Scottish Birds, 19, 290-298. In 1996 and 1997, the numbers of breeding hen harriers in Orkney’s West Mainland were estimated to have declined by about two thirds since the 1970s. Part of the reason for this decline may be reduced food availability associated with land use change. There has been major moorland reclamation since 1932. Most of the harriers nest in core moorland areas which are SSSIs, but on the moorland fringes, which were once preferred hunting areas, high stocking densities and intensive farming have led to a loss of semi-natural vegetation.
Miller, G.R. & Cummins, R.P. (1982) Regeneration of Scots Pine Pinus sylvestris at a natural tree-line in the Cairngorm mountains, Scotland. Holarctic Ecology, 5, 27-34.
Miller, G.R., Miles, J. & Heal, O.W. (1984) Moorland management: a study of Exmoor. Institute of Terrestrial Ecology, Cambridge, UK. The Exmoor National Park is 19000 ha of diverse moorland vegetation. However, current economics and favourable soil conditions encourage the conversion of moorland to seeded grassland. Heavy grazing also encourages the spread of grasses at the edge of the moors. The report describes the flora and fauna on Exmoor, the impact of existing management systems and discusses alternative management systems and the possible changes in vegetation that might result from their implementation.
Mitchell-Jones, A.J. & Gent, A.H. (1997) Priority natural areas for mammals, reptiles and amphibians. English Nature Research Report No. 242. English Nature, Peterborough, UK.
Morris, M.G. (1978) Grassland management and invertebrate animals - a selective review. Scientific Proceedings of the Royal Dublin Society, 6, 247-257. Grassland management can be divided into that which changes grassland and that which maintains it. All management can affect associated invertebrate faunas. Several management practices and possible effects on invertebrates are discussed.
Mortimer, S.R., Turner, A.J., Brown, V.K., Fuller, R.J., Good, J.E.G., Bell, S.A., Stevens, P.A., Norris, D., Bayfield, N. & Ward, L.K. (2000) The nature conservation value of scrub in Britain. JNCC Report No. 308. Joint Nature Conservation Committee, Peterborough, UK. Scrub is almost entirely a product of mans’ activities and often exists as a mosaic with grassland and other open vegetation. Its distribution, ecology, management and conservation are discussed.
Moss, C.E. (1913) Vegetation of the Peak District. University Press, Cambridge, UK. The work is the result of a botanical survey of the Peak District of the southern Pennines begun in 1903. The major plant communities and their vegetation associations are described. Cultivated land and land use are also discussed.
Moss, D., Taylor, P.N. & Easterbee, N. (1979) The effects on song-bird populations of upland afforestation with spruce. Forestry, 52 (2), 129-150. In Scotland, breeding birds were censused on upland moorland grazed by sheep and in spruce plantations at different stages of growth. Total song-bird densities and species diversity were highest in trees over 20 years old. Diverse forest structure and unforested upland areas are recommended.
204 Mowle, A. & Bell, M. (1988) Rural policy factors in land-use change. Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 165-182. Blackwell Scientific Publications, Oxford, UK. The major upland land uses, hill farming and forestry, attract high levels of subsidy. The paper details recent policy developments and any resulting land-use and environmental changes.
Murray, S., Hinds, P., Davenhill, A., Morris, S. & O’Brien, M. (1995) Numbers of lowland breeding waders in northern England 1993. Unpublished report. RSPB, Sandy, Beds., UK. The survey was carried out on agricultural land graded 1-4, principally on five wader species. Lapwing was the most commonly occurring species of wader. The density of breeding waders in the Pennine Dales ESA was twice the average density in northern England sites as a whole, and some sites: Baldersdale/Lunedale and Upper Teesdale, had higher than overall wader densities in the ESA. The Lake District ESA had a low density of birds.
Musgrove, A., Pollitt, M., Hall, C., Hearn, R., Holloway, S., Marshall, P., Robinson, J. & Cranswick, P. (2001) The Wetland Bird Survey 1999-2000 Wildfowl and Wader Counts. Published by the BTO, WWT, RSPB and JNCC, Slimbridge, UK.
Mutch, W.E.S. (1984) Ecological principles in upland management. Agriculture and the Environment. ITE symposium No. 13 (ed. D. Jenkins), pp. 135-139. Institute of Terrestrial Ecology, Cambridge, UK. The managed ecosystems of the uplands are restricted by topography, climate and soils. They are usually best used by grazing animals. The pattern of land use on hill land has changed over the last 20 years due to changes in financial circumstances.
Nature Conservancy Council. (1987) Research and survey in nature conservation, No. 6. Changes in the Cumbrian countryside. Nature Conservancy Council, Peterborough, UK. Details of changes in the extent of about 30 countryside features which have occurred between 1940s and 1970s, in lowland, intermediate and upland. Changes include loss of broad-leaved woods, an increase in coniferous woods, an increase in arable land, and loss of dwarf shrub heath. Most losses have occurred in semi-natural habitats.
Nature Conservancy Council. (1990a) The Uplands. Focus on Nature Conservation Series No. 25: Nature Conservation and agricultural change, pp. 14-20. Nature Conservancy Council, Peterborough, UK. Brief summary of the importance of the uplands, the impact of agriculture and agricultural policies.
Nature Conservancy Council. (1990b) The beef sector. Focus on Nature Conservation Series No 25: Nature Conservation and agricultural change, pp. 28-30. Nature Conservancy Council, Peterborough, UK. Intensification of beef production in the LFAs has had adverse effects on upland rough grazing. Pastures have been enclosed and agriculturally intensified to support specialist beef breeds. Silage production is more common and the use of fertilisers has increased.
Nature Conservancy Council. (1990c) Heather regeneration in England and Wales. Report for the Department of the Environment. Nature Conservancy Council, Peterborough, UK. The study covered the LFAs of England and Wales and aimed to identify existing use of and threats to heather, and asses the effectiveness of proposed methods to reduce heather loss. In 1947 there were 4571 sq. kms of upland heather. By 1980, 3352 sq. kms remained, mainly due to forestry, agricultural improvement, bracken encroachment and expansion of upland grasses.
Nelson, T.H. (1907) The Birds of Yorkshire: a historical account of the avifauna of the county. A. Brown & Sons, Hull & London, UK. Provides descriptions of breeding distributions of and habitat use by breeding birds in the uplands of Yorkshire in the 19th and early 20th Centuries.
Nethersole-Thompson, D. (1961) The breeding behaviour and breeding biology of the lapwing. The Birds of the British Isles, Volume 10 (eds. D.A. Bannerman & G.E. Lodge), pp. 265-274. Oliver & Boyd, Edinburgh,UK. Refers to an early count of lapwing breeding population on the hill-edge.
Newbould, P. (1985) Improvement of native grassland in the uplands. Soil use and management, 1 (2), 43-49.
205 Hill and upland areas make up more than one third of the total land area available for agriculture. Techniques for improving the quality and quantity of herbage produced from indigenous hill pasture are described. The key to efficient livestock rearing in the uplands lies in pasture improvement.
Newton, I., Davis, P.E. & Davis, J.E. (1982) Ravens and buzzards in relation to sheep farming and forestry in Wales. Journal of Applied Ecology, 19, 681-706.
Newton, I, Davis, P.E. & Moss, D. (1981) Distribution and breeding of red kites in relation to land-use in Wales. Journal of Applied Ecology, 18, 173-186. Most kites nest in oakwoods that occur mainly at boundary between lowland farmland and upland. Early in breeding season the birds feed on carrion from the uplands, but later in season they feed on prey which is more plentiful on farmland. Early stages of afforestation may benefit kites as more prey becomes available. Pasture improvement may also benefit the birds.
Newton, I., Davis, P.E. & Moss, D. (1996) Distribution and breeding of red kites Milvus milvus in relation to afforestation and other land-use in Wales. Journal of Applied Ecology, 33, 210-224. Conifer afforestation appears not to have affected kite population. However, kites prefer native oaks and other broad-leaved trees in which to nest and this is the main feature influencing their distribution. These oakwoods occur chiefly at the boundary between low farmland and the upland.
Newton, I., Meek, E.R. & Little, B. (1978) Breeding ecology of the merlin in Northumberland. British Birds, 71, 376-398. Much of the traditional open habitat of merlins has been converted to plantation forest. Merlins breed only in open sheep walk, heather moor or young plantations within 1 km of open ground. Heavy grazing pressure leads to ground vegetation too short for ground-nesting. Afforestation of open land reduces both nesting and feeding areas though they use planted areas until trees reach thicket stage. Merlins forage mainly in open areas.
Nolan, A.J., Still, M.J., Bell, J.S. & Gauld, J.H. (1997) Botanical changes in unimproved enclosed grasslands of the Breadalbane ESA, Scotland, 1989-1993. Grassland management in ESAs. BGS Occasional Symposium No. 32 (ed. R.D. Sheldrick), pp. 271-273. British Grassland Society, Reading, UK. The paper focuses on the areas of unimproved pasture towards the upper limit of enclosed agricultural land. The fields receive little or no artificial fertiliser and are noted for their floristic diversity. They were designated an ESA to preserve the conservation value of the land. Results of management guidelines are discussed.
Nuttall, J. (1972) The status and distribution of the twite (Carduelis flavirostris) in East Lancashire with some notes on its breeding biology. Naturalist, 923, 140-141. Breeding numbers of twite in 1967 and 1968. Post-breeding flocks of up to 300 feed on neglected pastures.
O’Brien, M., Green, M., Harris, A. & Williams, I. (1998) The numbers of breeding waders in Wales in 1993. Welsh Birds, 2, 35-42. The continuing decline in breeding wader populations indicate a problem in the Welsh countryside, though it is unclear whether this is due to habitat change or other factors. Only curlew, lapwing and snipe were found in sufficient numbers to estimate the total Welsh breeding population.
O’Brien, M. & Murray, S. (1998) The number of breeding waders on farmland in northern England in 1993. WSG Bulletin, 85, 60-65. Breeding wader populations on lowland farmland - classified as agricultural land grade 1-4, up to the moorland edge - were estimated. The average density of waders recorded on the Pennine Dales ESA was higher than elsewhere in region. Wader densities on Baldersdale/Lunedale and Upper Teesdale are comparable with other sites known for their high wader densities. Northern England has 25-30% of the total population of curlew and lapwing.
Ogilvie, M. & the Rare Breeding Birds Panel. (2001) Rare breeding birds in the United Kingdom in 1999. British Birds, 94, 344-381. The relict breeding population of red kites in central Wales increased from 54 breeding pairs (71 total pairs) in 1989 to 181 breeding pairs (228 total pairs) in 1999.
Orford, N. (1973) Breeding distribution of the twite in central Britain. Bird Study, 20, 51-62.
206 Birds feed almost entirely on the upland pastures but nest in shrubby vegetation at a higher level, within 1.5 km of feeding ground. From spring to autumn, birds roost in bracken on the edges of the moors.
Page, C.N. (1982) The history and spread of bracken in Britain. Proceedings of the Royal Society of Edinburgh, 81B, 3-10. Before the arrival of man in Britain, bracken was an open woodland and forest margin species. However, with the removal of the forest canopy, the plant has spread rapidly. In open conditions, bracken has a greater spore output than in more shaded ones. Burning and selective sheep grazing removes natural vegetation competition, allowing the spread of bracken.
Pakeman, R.J., Le Duc, M.G. & Marrs, R.H. (1997) Moorland vegetation succession after the control of bracken with asulam. Agriculture, Ecosystems and Environment, 62, 41-52. Bracken control with herbicide had been carried out on a range of sites in the North York Moors. Vegetation change after spraying depended on the initial effectiveness of the treatment and the amount of subsequent disturbance, mainly be sheep. Where grazing pressure was low, there was little invasion or spread of plants. Where disturbance by sheep was high, invasion by moss was followed by an increase in dominance by grasses. Some grazing slowed bracken regeneration, but in the short term (less than 10 years) simply controlling the bracken would not result in the development of a heathland community.
Pakeman, R.J., Le Duc, M.G. & Marrs, R.H. (2000) Bracken distribution in Great Britain: strategies for its control and the sustainable management of marginal land. Annals of Botany, 85 (Supplement B), 37-46. Bracken is perceived as a widespread and increasing problem. However, pollen records suggest that current abundance of bracken is less than or equivalent to maximum historical levels. There is a potential for increased bracken dominance in northern Britain. However, this may be offset by changes in the extent of other vegetation types at the expense of bracken. Many control attempts do not result in long-term success, as the control is often not followed by aftercare.
Pakeman, R.J. & Marrs, R.H. (1992) The conservation value of bracken Pteridium aquilinum (L.) Kuhn- dominated communities in the UK, and an assessment of the ecological impact of bracken expansion or its removal. Biological Conservation, 62, 101-114. Bracken stands are usually poor floristically and generally have a poor fauna. Further spread of bracken will lead to the loss of other habitats with high conservation value and thus a decline in uncommon species. Bracken control is expensive and there may be problems of revegetation.
Pakeman, R.J., Marrs, R.H., Howard, D.C. & Barr, C.J. (1995) Predicting the effects of climate and land-use change on the spread of bracken. Bracken: an environmental issue. International Bracken Group Special Publication No. 2 (eds. R.T. Smith & J.A. Taylor), pp. 69-72. University of Wales, Aberystwyth, UK. The Countryside Survey 1990 and the Land Cover Map both identify the size of the bracken problem and the areas where the problem is concentrated. Institute of Terrestrial Ecology surveys also show the distribution of bracken between 32 land classes which can help to identify where bracken encroachment could occur as a result of land use change. A model of bracken growth constructed in relation to management and climate has been created. An improvement in climatic conditions will lead to an increase in stand biomass particularly in the southern uplands of Scotland and the Grampians. Encroachment from land use change is more likely in the south-west and Wales, and the upland margins of northern England.
Pakeman, R.J., Marrs, R.H., Howard, D.C., Barr, C.J. & Fuller, R.M. (1996) The bracken problem in Great Britain: its present extent and future changes. Applied Geography, 16 (1), 65-86. Bracken has expanded as a result of changing management practices over the last few centuries. Rural depopulation and reductions in the intensity of upland farming have reduced bracken management and allowed invasion into previously cultivated areas. The 1990 Countryside Survey showed that bracken cover was particularly high in Wales (4.3% of the land surface) and in land classed as marginal uplands. Comparison of the 1990 survey with one completed in 1984 shows that there has been a decrease in bracken-dominated area, though this reduction may not reflect an increase in grazing or conservation value.
Parr, R. (1980) Population study of golden plover Pluvialis apricaria, using marked birds. Ornis Scandinavica, 11, 179-189. At Kerloch, Kincardineshire, golden plover tend to breed on parts on the moor near fields where they feed on earthworms and invertebrates.
207 Parr, R. (1992) The decline to extinction of a population of golden plover in north-east Scotland. Ornis Scandinavica, 23, 152-158. Many golden plover populations have declined. Several explanations have been put forward including afforestation, loss of moorland habitat and increased predation. At Kerloch, north-east Scotland, decreases in the number of birds followed poor survival during severe winters. High nest predation prevented population recovery and predation levels were probably related to protection given to predators by afforestation.
Parr, R. & Watson, A. (1988) Habitat preferences of black grouse on moorland-dominated ground in north-east Scotland. Ardea, 76, 175-180. Leks occur on flat ground at moorland edge and close to woods. Changes in land use, particularly overgrazing, drainage and afforestation are destroying the habitat which could lead to a decline in numbers.
Parr, S.J. (1991) Occupation of new conifer plantations by merlins in Wales. British Birds, 38, 103-111. Between 1948 and 1983, 18.4% of the Cumbrian Mountains ESA was converted from grass moorland to conifer plantation. Merlins switched nest sites from moorland trees to the edges of conifer plantations. The altitude of nesting sites also increased, but tended to be near old upland valley nest areas. It is possible that merlin numbers may not have declined but that these new nesting sites have been overlooked.
Parry, M., Bruce, A. & Harkness, C. (1981) The plight of British moorlands. New Scientist 90 (1255): 550- 552. The areas of moorland and roughland throughout England and Wales have been declining due to reclamation for improved grassland or forestry, at an estimated average rate of 5000 ha/year. The rate of reclamation has increased since the 1950s and much is ‘primary’ moorland that is ploughed for the first time.
Parry, M. & Sinclair, G. (1985) Mid-Wales uplands study. Countryside Commission, Cheltenham, UK . A study of land use change between 1948-1983. There has been a decrease in the area of rough pasture and a gain in the area of coniferous woodland and improved farmland. Land reclaimed for agriculture is often temporary and reverts back to rough pasture: 48% of reclamation between 1948 and 1983 was temporary. Coniferous afforestation rarely reverts. Between 1951 and 1981, farmed areas reduced due to a transfer to forestry, yet there was an 80% increase in stock density.
Parry, M.L. (1977) Occasional publication No. 4. A framework for land use planning in moorland areas. University of Birmingham, Birmingham, UK. A report based on research on the Dark Peak area of the Peak District National Park, which discusses a method of classifying moorland areas on the basis of their reclamation history, and recommends broad types of land use policy that are best suited to each moorland type. With the use of aerial photography and maps, a moorland core could be identified, which has consistently been mapped as moorland since at least 1870, and covers about 82% of the present moorland area. As this is ‘natural’ moorland, it needs a conservation-orientated land use policy. Around the core is the moorland fringe, which has fluctuated between moorland and improved land or woodland between 1870 and 1970. This covers 11% of the Dark Peak. Land use zoning should recognise these areas as being ecologically distinct from unbroken moorland.
Parry, M.L., Bruce, A. & Harkness, C.E. (1982a) Surveys of moorland and roughland change No 4. Changes in the extent of moorland and roughland in the Northumberland National Park. University of Birmingham, Birmingham, UK. Report detailing the results of a survey of changes in the extent of open moorland over the past 115 years (1861- 1976), particularly at the moorland edge. Changes between rough pasture and improved farmland and rough pasture and woodland have been mapped. OS maps were used as a source for changes between 1861-1976. Changes prior to 1861 taken from aerial photographs. In 15 years, rough pasture has declined by about 20%. The rate of reduction has increased since 1952. Nearly 80% of moorland conversion has been to woodland. At least 25% of recent reclamation (1952-76) is of farmland which had reverted to rough pasture in the 1930s. Areas at the moorland edge tend to fluctuate between rough pasture and improved land, which indicates land on the margins of profitability.
Parry, M.L., Bruce, A. & Harkness, C.E. (1982b) Surveys of moorland and roughland change No. 5. Changes in the extent of moorland and roughland in the North York Moors. University of Birmingham, Birmingham, UK. The results of a survey of changes in the extent of open moorland over the past 130 years (1853-1979). During this period, rough pasture has declined by 29%. This decline was less in the 1960s and 1970s due to a decrease
208 in afforestation. An increasing proportion of improvement comprises of the re-intake of regenerated rough pasture. Nearly 75% of moorland conversion has been to woodland rather than improved farmland.
Parry, M.L., Bruce, A. & Harkness, C.E. (1982c) Surveys of Moorland and Roughland Change No. 10. Changes in the extent of moorland and roughland in the Lake District National Park. University of Birmingham, Birmingham, UK. Results of a survey of changes in the extent of open moorland over the past 114 years (1860-1974). Over this period rough pasture has decreased by about 1.4% of which 72% has been to woodland rather than improved farmland. Conversion has been primarily of unimproved moorland.
Parry, M.L., Bruce, A. & Harkness, C.E. (1982d) Surveys of Moorland and Roughland Change No. 8. Changes in the extent of moorland and roughland in northern Snowdonia National Park. University of Birmingham, Birmingham, UK. Results of a survey of changes in the extent of open moorland over the past 88 years (1887-1975). In 88 years, rough pasture has decreased by about 8%. There has been a slight increase in this rate, mostly due to afforestation, primarily of unimproved moorland.
Parry, M.L., Bruce, A. & Harkness, C.E. (1982e) Surveys of Moorland and Roughland change No. 7. Changes in the extent of moorland and roughland in the Brecon Beacons National Park. University of Birmingham, Birmingham, UK. Results of a survey of changes in the extent of open moorland over the past 90 years (1885-1975). In 90 years, rough pasture has declined by 11%. Most of this conversion occurred between 1948 and 1975. Conversion slowed down in the 1960s and 1970s due to a decrease in afforestation. The pace of improvement has declined. The pattern of reclamation and reversion indicates a general retreat downhill by the limit of improved farmland.
Parry, M.L., Bruce, A. & Harkness, C.E. (1982f) Surveys of Moorland and Roughland Change No. 6. Changes in the extent of moorland and roughland on Dartmoor. A preliminary survey to 1971. University of Birmingham, Birmingham, UK. Results of a survey of changes in the extent of open moorland over the past 97 years (1885-1971). In 86 years, rough pasture has declined by 5%. Most conversion occurred between 1958 and 1971, mainly due to reclamation rather than afforestation, with some concentration along the moorland edge.
Parry, M.L., Bruce, A. & Harkness, C.E. (1984) Surveys of Moorland and Roughland Change No. 9. Changes in the extent of moorland and roughland in the Yorkshire Dales National Park. University of Birmingham, Birmingham, UK. Results of a survey of changes in the extent of open moorland over the past 132 years (1848-1980). In 132 years, rough pasture has increased by 12% which is more the result of a reclassification of Festuca-Agrostis grassland from improved land to moorland. Overall, the total area under rough pasture in 1980 is similar to that in 1848, though its regional pattern or distribution has altered.
Parry, M.L., Mathieson, C.W., Bruce, A. & Harkness, C.E. (1982) Surveys of Moorland and Roughland change No. 11. Changes in the extent of moorland and roughland on Dartmoor. A supplementary survey to 1979. University of Birmingham, Birmingham, UK. Additional results of a survey of changes in the extent of open moorland between 1971 and 1979. Reclamation has slightly exceeded reversion and most of this is secondary intake of previously improved land. There has been no primary afforestation of open moorland.
Payne, R. & Whitmore, C. (1985) CSD Notes No. 39. Upland habitat change review. Nature Conservancy Council, Peterborough, UK. Summaries of research carried out on upland habitat change.
Peak District National Park. (2002a) Unimproved Pastures Action Plan. http://www.peakdistrict.org In the Peak District there is estimated to be less than 1500 ha. of unimproved pastures, with a dramatic loss of this habitat. Unimproved pastures have a high botanical interest, and provide an essential habitat for a range of national BAP species, such as skylarks. The targets of the action plan are listed, along with the action required for their achievement.
Peak District National Park. (2002b) Rush Pasture Action Plan. http://www.peakdistrict.org
209 Rush pasture is widespread in the Dark and South West Peak river valleys and along the moorland fringe. It is important for other BAP species such as skylarks and black grouse. Traditionally used for light grazing, they have come under pressure from drainage and increased stocking rates. It often exists as a transition and buffer zone between the intensively used inbye land and the moorlands. The targets of the Action plan are listed along with the action required for their achievement.
Peak District National Park. (2002c) Lead Rakes Action Plan. http://www.peakdistrict.org Mining in the White Peak has resulted in a network of hillocks and hollows across the limestone plateau and dalesides. They support a mosaic of vegetation types due to their range of topography and variations in the waste material. There has been an estimated 50% loss of the habitat this century and the decline continues. The targets of the Action Plan are listed, along with the action required for their achievement.
Peak District National Park. (2002d) Rough Grazing Action Plan. http://www.peakdistrict.org Rough grazings are made up of unimproved and semi-improved grassland, and provide habitats for a range of plant communities and their associated insect, bird and mammal populations. Loss of habitat to direct agricultural improvement should be limited as many areas are inaccessible to machinery, though some sites will have declined in quality due to an increase in stock numbers. The targets of the Action Plan are listed, along with the action required for their achievement.
Peak District National Park. (2002e) Upland Oak/Birchwoods Action Plan. http://www.peakdistrict.org Nationally, upland semi-natural woodland has declined by about 30-40% over the last 60 years. In the Peak District, rates of loss vary between 8-68%. They often support ancient woodland communities, and the interface between woodland and moorland is of particular wildlife and landscape value. The targets of the Action Plan are listed, along with the action required for their achievement.
Peak District National Park. (2002f) Twite Action Plan. http://www.peakdistrict.org The twite is the bird with the highest conservation priority within the Peak District, as the area holds one quarter of the South Pennines population. It is dependent on moorland for nesting and moorland fringe habitats for feeding and is vulnerable to habitat change. There has been a 50% decline in the population of the South Pennines in the last ten years, partly due to the decline in quality and extent of upland hay pastures. The targets of the Action Plan are listed, along with the action required for their achievement.
Peak District National Park. (2002g) Curlew Action Plan. http://www.peakdistrict.org Between 1985 and 1996 there has been a decrease in the number of breeding pairs found on inbye land due to adverse land management. The population present on the moorland areas appears to have remained stable. The targets of the Action Plan are listed, along with the action required for their achievement.
Peak District National Park. (2002h) Lapwing Action Plan. http://www.peakdistrict.org Over the last 30 years the lowland breeding population of the lapwing has declined, with a partial census in 2000 suggesting a population of only 700-800 pairs in the Peak District. Inbye pasture fields are particularly important for breeding, and the loss of upland farms and the intensification of upland pasture management will accelerate it’s decline in the Peak District.
Pearce-Higgins, J.W. & Grant, M.C. (2001) Variation in moorland bird distribution across grazing-related habitat gradients. Unpublished report. RSPB, Sandy, Beds., UK. Significant increases in sheep numbers have led to heather loss in England and Wales. Grazing also leads to structural changes in vegetation by reducing vegetation height. British heather moorland provides significant breeding or foraging habitat for 40 bird species. Stonechats and whinchats would benefit from reductions in grazing, whereas skylark, golden plover and wheatear favour short vegetation.
Pearce-Higgins, J.W. & Grant, M.C. (2002) The effects of grazing-related variation in habitat on the distribution of moorland skylarks Alauda arvensis and meadow pipits Anthus pratensis. Aspects of Applied Biology, 67, 155-163. Increases in livestock grazing have led to changes in moorland vegetation which can affect bird populations. Research on moorland in south Scotland and north England shows grazing results in the conversion of heather to grass and is likely to favour skylarks. Meadow pipits prefer a mix of dwarf shrubs and grass, preferably rough grassland.
Pearsall, W.H. (1950) Mountains and Moorlands. Collins New Naturalist, Collins, London, UK.
210 Summarises land use history of uplands in Britain, including deforestation and conversion of cleared land to grazing.
Penford, N. & Francis, I. (1990) Common land and nature conservation in England and Wales. British Wildlife, 2 (2), 65-76. In the uplands, common land is the moor adjacent to the farm with grazing rights. It is an important wildlife habitat that is increasingly under threat from afforestation and agricultural intensification. In Wales, these ‘ffridd’ areas have suffered the greatest loss, followed by heather moorland. Bracken is a characteristic feature and supports a distinctive bird community.
Penford, N., Francis, I.S., Hughes, E.J. & Aitchison, J.W. (1990) Biological Survey of Common Land No. 10: Radnor District, Powys. Rural Surveys Research Unit, Aberystwyth, UK. There are 67 commons in Radnor which cover 14% of the land area. During the survey, bracken was found to be the dominant vegetation, covering 36% of the common land area. Dry dwarf shrub heath covered 21% of the area but was declining due to overgrazing and burning, to be replaced by dry heath-grass mosaic. The upland areas and the bracken dominated ffridd are important for birds. Overgrazing is the biggest threat to the Radnor commons and the ffridd is not regenerating due to overgrazing and tree planting.
Penford, N., Francis, I., Hughes, E., Finch, M. & Aitchison, J. (1989) Biological Survey of Common Land No. 2: Carmarthenshire. Rural Surveys Research Unit, Aberystwyth, UK. There are 111 commons which cover 12.6% of the county area. The dominant vegetation types are Molinia caerulea grassland, Nardus stricta grassland or a mosaic of dwarf shrub heath and acid grassland. Heathland appears to have undergone a serious decline due to overgrazing. The bracken covered slopes are important for birds.
Petty, S.J. & Anderson, D.I.K. (1989) A decrease in carrion crow Corvus corone numbers following sheep removal and afforestation. Naturalist, 114, 81-84. Afforestation of a previously sheep-grazed area led to a decline in breeding density of crows, probably due to a decline in food availability.
Phillips, J., Yalden, D. & Tallis J. (eds.) (1981) Peak District Moorland Erosion Study. Phase 1 Report. Peak Park Joint Planning Board, Derbyshire, UK. The study, commissioned in 1979, examines the increasing erosion of the moorlands, the symptoms, causes and remedial action. About 8% of the Peak District moorlands is bare ground or severely eroding and major vegetation changes has occurred over the past 70 years, putting large areas at risk, although the overall extent of moorland has changed little. The major loss has been to forestry but heather has diminished due to a reduction of grouse moor management and increases in sheep numbers. Past and present vegetation of the Peak District are discussed.
Pigott, C.D. (1978) Climate and vegetation. Upper Teesdale: the area and it’s natural history (ed. A. R. Clapham), pp. 102-121. Collins, London, UK. Description of how climate alters with altitude and the effects on vegetation growth. Although examples are taken from Upper Teesdale, the principles apply to all upland areas.
Poxton, I.R. (1986) Breeding ring ouzels in the Pentland Hills. Scottish Birds, 14, 44-48. Nesting sites and behaviour of birds in an area of the Pentland Hills are described. Most birds nested on the banks of a stream or reservoir, under heather on a steep slope. Communal feeding areas were situated in pasture at the bottom of a valley.
Ratcliffe, D.A. (1976) Observations on the breeding of the golden plover in Great Britain. Bird Study, 23, 63- 116. In spring and early summer the bird is associated with moorlands but still feeds on the improved and enclosed grasslands at the moorland edge. Breeding occurs on unenclosed land, but nesting grounds are within easy flight of the permanent pastures, which are subject to heavy grazing and artificial fertilizers, but have higher populations of invertebrates. Breeding density tends to be higher in areas close to grassland providing good feeding areas. However, agricultural improvements encroaching on moorland fringes can lead to unsuitable breeding habitat and a reduction in the population.
Ratcliffe, D.A. (1977a) Uplands and birds-an outline. Bird Study, 24 (3), 140-158.
211 Where grouse moors have been maintained, heather is dominant, but where sheep have grazed over a long time, grassland and bracken have replaced the heather. Food supply is the primary factor determining the distribution and abundance of upland birds. There is an obvious reduction in species diversity with increasing elevation. Curlew, lapwing, snipe, redshank and yellow wagtail belong especially to marginal land and hill meadows, whilst golden plover and twite breed on the moors and feed in the fields.
Ratcliffe, D.A. (1977b) Woodland Birds. A Nature Conservation Review, Volume 1 (ed. D.A. Ratcliffe), pp. 360-361. Cambridge University Press, Cambridge, UK. The increase in afforestation on formerly treeless land has allowed the spread of some bird species, such as the black grouse, but replacing broad-leaved woods by coniferous plantations reduces the populations of birds which do not favour conifers. In Wales, the red kite breeds in wooded upland valleys, but it also uses hill farmland and open moorland for feeding. All these habitats need to be conserved.
Ratcliffe, D.A. (1978) The plant communities of Upper Teesdale. Upper Teesdale: the area and it’s natural history (ed. A.R. Clapham), pp. 64-87. Collins, London, UK. Description of vegetation in Upper Teesdale, from the enclosed grasslands up to the higher grasslands and heaths.
Ratcliffe, D.A. (1990) Bird Life of Mountain and Upland. Cambridge University Press, Cambridge, UK. Upland habitats are open, unenclosed areas that lie above the limits of cultivation. Of particular interest are the Introduction and Chapters 1 - The birds and their habitat, 2 - The sheep walks, 3 - The grouse moors, 8 - Geographical aspects of the upland bird fauna, and 9 - Conservation of upland birds.
Raynor R. (2002) Water voles in the Highlands. British Wildlife, 13, 255-257. Identifies important relict populations of water voles in upland rivers and streams.
Redpath, S.M. (1992) Behavioural interactions between hen harriers and their moorland prey. Ornis Scandinavica, 23, 73-80. Hen harriers prefer to catch grouse chicks and lagomorph young, but when larger prey are scarce, small prey such as passerines and small mammals are hunted. In this situation, harriers hunt according to passerine distribution. Passerines prefer edge habitats.
Redpath, S., Madders, M., Donnelly, E., Anderson, B., Thirgood, S., Martin, A. & McLeod, D. (1998) Nest site selection by hen harriers in Scotland. Bird Study, 45, 51-61.
Reed, S. (1995) Factors limiting the distribution and population size of twite (Carduelis flavirostris) in the Pennines. Naturalist, 120, 93-102. Nesting colonies of twite are associated with moorland vegetation, but hay meadows, unimproved pastures and disturbed ground are used for feeding. Recent declines could be due to a decline in hay-making and agricultural improvement of hay meadows and pasture.
Rees, S., Charles, R. & Wightman, S. (eds.) (2001) Moorland Research Review 1990-1995. North York Moors Park Authority, Helmsley, UK. The review gives an update on research work that has been carried out on the North York Moors between 1990 and 1995. This includes studies on heather, bracken, moorland birds, woodlands and mapping. Information from this research will be used in developing the Moorland Regeneration Programme.
Roberts, B.K. (1978) Man and land in Upper Teesdale. Upper Teesdale: the area and it’s natural history (ed. A.R. Clapham), pp. 141-159. Collins, London, UK. Definitions given of ‘inby’ and ‘outby’ land. Human activity has led to vegetation changes; from open woodland to a grass/heather mosaic in Upper Teesdale.
Roberts, H.W. (1988) Annex 3: Management prescriptions for the control of bracken. Bracken in Wales. The Senior Technical Officer’s Group, Wales, pp. 44-46. Nature Conservancy Council, Bangor, UK. Bracken encroachment is thought to be primarily due to changes in management such as an increase in sheep numbers, a reduction in cattle numbers, a reduction in cutting and use of bracken for bedding. Bracken control, particularly on in-bye land would be worthwhile financially, particularly with government aid. Data on grant aid are given.
212 Robson, G. & Percival, S.M. (2002) The use of marginal farmland by curlew Numenius arquata breeding on upland moors. Aspects of Applied Biology, 67, 75-82. Marginal farmland fields are an important feeding area for curlew breeding on moorland. They forage in pastures, hay meadows and rough grazing but prefer large fields close to the moor. Golden plover and twite also use farmland adjacent to the moor for feeding.
Robson, M.J., Parsons, A.J. & Williams, T.E. (1989) Rough and hill grazings. Grass. It’s production and utilization, (ed. W. Holmes), pp. 72-74. Blackwell Scientific Publications, Oxford, UK. Description of vegetation found on rough and hill grazings.
Robson, R.W. & Williamson, K. (1972) The breeding birds of a Westmorland farm. Bird Study, 19, 202-214. Describes breeding bird community on hill-edge farm near Appleby in Cumbria.
Rodwell, J.S. (1991a) British Plant Communities Volume 1. Woodlands and scrub. Cambridge University Press, Cambridge, UK.
Rodwell, J.S. (1991b) British Plant Communities Volume 2. Mires and Heaths. Cambridge University Press, Cambridge, UK.
Rodwell, J.S. (1998) British Plant Communities Volume 3. Grasslands and montane communities. Cambridge University Press, Cambridge, UK.
Rodwell, J.S. (2000) British Plant Communities Volume 5. Maritime communities and vegetation of open habitats. Cambridge University Press, UK.
RSPB. (1984) Hill farming and birds: a survival plan. RSPB, Sandy, Beds., UK. Britain’s moorland birds are being threatened by a variety of hill-farming practices and conifer afforestation. Peripheral upland blocks tend to lose their species first, with agricultural improvement being the main cause of loss in the English and Welsh uplands. The RSPB proposes a system of grants, allowances and advice in order to support hill farming but also meet the demands of nature conservation.
RSPB. (1986) Reclamation and afforestation of moorland in mid Wales. RSPB, Sandy, Beds., UK. Between 1971 and 1985, the area of moorland within twenty-one 10 km squares was reduced by 12%. Of this, 63% was due to land reclamation and 37% to afforestation. Reclamation affected isolated moorland plots within areas of improved pasture, and also plots at the fringes of main moorland blocks. Both types of conversion led to further fragmentation of moorland. Most upland bird species make some use of pasture and inbye land. Ffridd land may be as important for birds as the adjacent moorland, but is under threat from land-drainage and re-seeding.
RSPB. (2002) Birds of the moorland fringe. Fieldfare, 20, May 2002. Gives brief report on Countryside Stewardship initiative to conserve breeding twite in the Pennines.
Rushton, S.P. & Luff, M.L. (1988) The use of multivariate ordination techniques to assess the effects of Chlorpyrifos on ground beetle and spider communities in grassland. Field methods for the study of environmental effects of pesticides. British Crop Protection Council Monograph. No. 40. pp. 175-181. The use of pesticides such as Chlorpyrifos on improved pasture systems can effect spider and ground beetle communities. There was no clear relationship between application and the number of individuals and species of each group. The frequency of use appears to be more important on non-target species.
Rushton, S.P., Luff, M.L. & Eyre, M.D. (1989) Effects of pasture improvement and management on the ground beetle and spider communities of upland grasslands. Journal of Applied Ecology, 26, 489-503. Species composition of improved sites was poor and similar to that on intensively managed pastures at lower altitudes. The frequency and use of organo-phosphorus pesticides influenced species composition of improved sites.
Sanderson, R.A., Rushton, S.P., Cherrill, A.J. & Byrne, J.P. (1995) Soil, vegetation and space: an analysis of their effects on the invertebrate communities of a moorland in north-east England. Journal of Applied Ecology, 32, 506-518.
213 The species composition of moorland invertebrate communities is affected by many factors but the relative contribution of environmental factors is often unclear. In this study, Auchenorhyncha communities were determined by soil conditions and vegetation species composition and Heteroptera by vegetation.
Savory T.H. (1952) The Spider’s Web. London, UK.
Senior Technical Officers’ Group. (1988) Assessment of the available evidence on the problems caused by bracken in Wales. Bracken in Wales. The Senior Technical Officers’ Group, Wales, pp. 10-31. Nature Conservancy Council, Bangor, UK. In mapping bracken cover, there is a need to define what is being mapped and how (from the ground or satellite imagery), as very different results can be obtained. It has been suggested that the area covered by bracken is currently increasing by 1% per year. This creates a problem by invading grassland and rough grazing, hindering stock management, harbouring sheep ticks and causing disease in stock if ingested in quantity. Marginal fields in particular, which have fallen into disuse, have been invaded by bracken. However, bracken is important for a variety of animals and plants. The positive and negative aspects of bracken and nature conservation, and of bracken control measures are discussed. A series of recommendations for action on bracken are given.
Shaw, G. (1995) Habitat selection by short-eared owls Asio flammeus in young coniferous forests. Bird Study, 42, 158-164. Afforestation of upland grasslands creates ideal conditions for field vole, which encourages owls. Forest of three to seven years old is preferred.
Shaw, M.W. (1988) Annex 2b: Ecology of bracken in relation to control methods. Bracken in Wales. The Senior Technical Officer’s Group, Wales, pp. 38-43. Nature Conservancy Council, Bangor, UK. Bracken is naturally a woodland species and does well in habitats that would support natural woodland. It’s growth is reduced in areas of impeded drainage and land use management also inhibits it’s growth. It cannot withstand repeated cultivation, but on marginal land, will re-invade if cultivation ceases. High stocking rates can suppress bracken growth and cattle are better than sheep. The increase in sheep numbers in the uplands may have helped the spread of bracken. Present methods of bracken control are largely dependent on upgrading marginal land so that changed agricultural management prevents re-invasion.
Shepherd, K. (2001) Yorkshire Dales National Park Enclosed Upland Breeding Wader Survey 2000, summary report. Royal Society for the Protection of Birds and the Yorkshire Dales National Park Authority. 18pp. Gives population estimates of breeding waders on enclosed hill-edge land in the Yorkshire Dales and presents comparative data from previous surveys of areas in the Dales and surveys of other areas.
Shepherd, K.B. (1993) Survey of breeding waders in Baldersdale and Lunedale, County Durham, England in 1993. Unpublished report. RSPB, Sandy, Beds., UK. Pasture and inbye land were surveyed in 1993. Most of the survey area formed part of the Pennine Dales ESA. The area was found to be of national importance for breeding waders. The results of the survey are discussed and the possible expansion of the ESA considered.
Shrubb, M. (1990) Effects of agricultural change on nesting lapwings Vanellus vanellus in England and Wales. Bird Study, 37, 115-127. Nesting performance in upland grass is now poor due to increased stocking rates leading to more nests lost to trampling. Grassland cultivation and increased cattle numbers cause more desertions.
Shrubb, M., Williams, I.T. & Lovegrove, R.R. (1997) The impact of changes in farming and other land uses on bird populations in Wales. Welsh Birds, 1 (5), 4-26. There has been widespread loss of habitat diversity due to reseeding and drainage, afforestation, loss of traditional shepherding techniques and increased stocking rates. Ffridd is important for passerine birds. However, this area is vulnerable to burning, and regeneration of scrub is limited by increased sheep grazing.
Sinclair, G. (1970) The vegetation of Exmoor. The Exmoor Press, Dulverton, Somerset, UK
Sinclair, G. (1983) The upland landscapes study. Environment Information Services, Dyfed, UK. The study looks at the current nature, condition and management of the uplands, the various economic activities and the upland areas that are likely to change if the present trends continue. The report is based on work carried out in 12 upland areas.
214 Small, C., Ullrich, P. & Mason, N. (1999) Breeding waders in Baldersdale and Lunedale, County Durham, England, 1993 and 1999. Unpublished report. RSPB, Sandy, Beds., UK. The Pennine Dales ESA contains areas with some of the highest densities of breeding waders in the British Isles. UK surveys in the 1980s and 1990s have shown that wader populations have declined, possibly due to agricultural improvement. This study showed that in the six years between surveys, oystercatcher pairs have increased, curlews and redshank have remained stable whilst lapwing and snipe numbers have declined.
Smith, M. (1985) Agriculture and nature conservation in conflict - The Less Favoured Areas of France and the UK. The Arkleton Trust, Dumfriesshire, UK. Nearly half of the land area of the UK is designated under the EEC Less Favoured Areas Directive, almost all of it upland. The implementation of this directive and the financial incentives provided under it, to support agriculture in the uplands, are the main factors causing conflict with conservation interests. This study shows how the Directive is implemented in Wales.
Smith, R.S. (1997) Upland meadow grasslands in the Pennine Dales Environmentally Sensitive Areas (ESA). Grassland management in ESAs. BGS Occasional Symposium No. 32 (ed. R.D. Sheldrick), pp. 80-90. British Grassland Society, Reading, UK. The management of upland meadows to maintain their plant species composition requires the continued application of traditional regimes: autumn grazing with cattle, no mineral fertilizer and a mid-July hay cutting date. A change in this regime can lead to a change in species composition.
Smith, R.T. (1986) Opportunistic behaviour of bracken (Pteridium aquilinum L. Kuhn) in moorland habitats: origins and constraints. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 215-224. Parthenon Publishing, Lancaster, UK. Bracken spread can be attributed to shifts in land use type and intensity. Ilkley Moor, where bracken expansion has occurred on the lower slopes of the moor, is used as a case study.
Sparke, C.J. & Williams, G.H. (1986) Sward changes following bracken clearance. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 225-231. Parthenon Publishing, Lancaster, UK. The suppression of bracken growth usually reveals a grass mixture, bracken litter and weeds. Spraying does not lead to long-term changes in the proportions of major sward components but less frequent species may disappear. To improve the quantity and quality of the sward, surface seeding may need to be carried out, though if the litter layer is not broken up, this may be unsuccessful.
Stace, C. (1997) New Flora of the British Isles, 2nd edn. Cambridge University Press, Cambridge, UK
Starling-Westerberg, A. (2001) The habitat use and diet of black grouse Tetrao tetrix in the Pennine hills of northern England. Bird Study, 48, 76-89. Grass habitats along lower moorland edge are preferred by birds in spring and summer, where grassland herbs make up a large proportion of the adult diet, and with high invertebrate numbers for chicks.
Stevens, J.P. (1992) Vegetation change in Llyn between 1920/2 and 1987/8. Countryside Council for Wales, UK. Vegetation details were mapped and then the maps superimposed to give details of vegetation change. Between 1920/2 and 1987/8, the overall area of semi-natural habitat had decreased by 47%, and 75% underwent some sort of change. Most habitat modification was due to agricultural intensification and expansion, though the type and degree of change varied greatly between vegetation types.
Stillman, R.A. (1995) Bird associations with heather moorland in the Scottish and English uplands. Heaths and moorland: cultural landscapes (eds D.B.A. Thompson, A.J. Hester & M.B. Usher), pp. 67-73. HMSO, Edinburgh, UK. In both the eastern Highlands and south Pennine areas, altitude and vegetation gradients from grassland to heather moorland were particularly associated with bird distribution. Red grouse, meadow pipit and merlin showed a positive correlation with heather moorland, while dunlin and skylark showed negative correlations. Other species showed no significant associations. Upland areas with a low range of habitat types are likely to have a lower bird species diversity.
215 Stillman, R.A. & Brown, A.F. (1994) Population sizes and habitat associations of upland breeding birds in the south Pennines, England. Biological Conservation, 69, 307-314. The south Pennines is an important breeding area for a number of bird species. Distance from the moor edge was important due to its correlation with topography and vegetation. Whinchat associated with bracken, wheatear with steep, grassy slopes, curlew, lapwing and snipe with low-altitude areas towards the edge of moorland blocks. Most species showed an association with vegetation cover type, so any changes in vegetation will affect a variety of species.
Stratham, D.C. (1972) CES UWP 16. Land use changes in the moorlands of the North York Moors National Park. Centre for Environmental Studies, London, UK. Within the study area, approximately 50% of the open moorland existing in 1933 had, by 1971, disappeared, due to agricultural improvement or afforestation. Most of these changes have taken place in a largely uncontrolled way. The competing uses, together with improved or reclaimed moorland, are evaluated on a relative basis, using a variety of factors, such as economy, ecology and recreation.
Stroud, D.A. & Reed, T.M. (1986) The effect of plantation proximity on moorland breeding waders. Wader Study Group Bulletin, 46, 25-28. Coniferous afforestation can lead to the loss and fragmentation of moorland as well as harbour predators of ground-nesting birds. In this study of nine moorland sites, the distribution of vegetation was different in areas close to plantations. Significantly fewer waders were found to use areas close to forestry plantations. This effect can be seen up to 800m from the moorland edge.
Stroud, D., Reed, T.M., Pienkowski, M.W. & Lindsay, R.A. (1987) Birds, bogs and forestry: the peatlands of Caithness and Sutherland. Nature Conservancy Council, Peterborough, UK. Assesses impact of afforestation on breeding populations moorland birds breeding in the Flow Country of northern Scotland.
Stuart, R. (1996) Bracken Survey 1996 Report. South Cumbria and North Lancashire endangered fritillaries project. Cumbria Wildlife Trust, Windermere, UK. Both the high brown fritillary and the pearl-bordered fritillary have suffered a contraction of range and are now nationally scarce species. Bracken has now become an important habitat for both species, particularly patchy bracken with a compact litter layer, abundant violets and dead bracken cover. This type of habitat is best maintained by traditional methods of bracken control.
Stuart, R. (1997) Endangered Butterflies Project 1997 Report. Cumbria Wildlife Trust, Windermere, UK. The high brown and pearl-bordered fritillaries are significantly dependent upon bracken habitats in south Cumbria. Management of bracken by grazing and seasonal cutting is recommended to produce a habitat mosaic. Marsh fritillaries prefer wet meadows, though few areas of suitable habitat are present in Cumbria.
Swan, M.J.S. & Oldham, R.S. (1993a) Herptile Sites: Volume 1: National Amphibian Survey. English Nature Research Report No. 38. English Nature, Peterborough, UK.
Swan, M.J.S. & Oldham, R.S. (1993b) Herptile Sites Volume 1: National Amphibian Survey Appendices 4 to 33. English Nature Research Report No. 38. English Nature, Peterborough, UK.
Swindells, D.W. (1997) Reduction in numbers of ground-nesting species in Upper Nidderdale. Harrogate and District Naturalists’ Society Bird Report for 1996 (ed. J.R. Mather), pp. 46-47. Harrogate and District Naturalists’ Society, Harrogate, UK. Ground-nesting birds have declined due to the elimination of rough grazing between pasture and moor, caused by heavy grazing, increase in silage, vehicles on land and drugs to control sheep disease leading to fewer invertebrates. Species nesting and feeding above ground are thriving.
Sydes, C. & Miller, G.R. (1988) Range management and nature conservation in the British uplands. Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 323-337. Blackwell Scientific Publications, Oxford, UK. Summary of how changes in land use, particularly grazing by sheep, have affected uplands.
Sykes, J.M., Lowe, V.P.W. & Briggs, D.R. (1989) Some effects of afforestation on the flora and fauna of an upland sheepwalk during 12 years after planting. Journal of Applied Ecology, 26, 299-320.
216 Afforestation and reduced grazing leads to changes in the frequency of occurrence of vascular plants and vertebrate animals.
Tallis, J.H. & Yalden, D.W. (1983) Peak District Moorland Restoration Project. Phase 2 Report: Re- vegetation trials. Peak Park Joint Planning Board, Derbyshire, UK. Erosion in the Peak District may be due to a combination of air pollution, climate, fire, low soil fertility, soil instability and grazing pressure. All these factors can also affect the repair of erosion. Grazing is a major inhibitor of moorland re-generation, but even if grazing is reduced, soil sources may be inadequate or allow only very slow regeneration. It may be necessary to totally exclude sheep for several years and in the worst affected areas, the addition of artificial seeding and fertilising may be required.
Taylor, J.A. (1974) Marginal physical environments. Colloquium Proceedings No. 4, pp. 10-29. Potassium Institute Ltd. Marginal zones are determined by rock, relief, soils, climate and water, but are variable in relation to vegetation and land use change. As settlements and agriculture have expanded, marginal zones have retreated upslope. They have also retreated downslope again with rural depopulation, the abandonment of high altitude farms, and the reversion of upland grazings to bracken, rush and scrub woodland. Therefore, marginal land is a plagiosere: a combined derivative of the physical environment and land use management. The vegetation of upland Wales was mapped between 1961 and 1966 and changes in vegetation between this survey and the 1936 Grass Survey of Wales (1936) are discussed.
Taylor, J.A. (1986) The bracken problem: a local hazard and global issue. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 21-42. Parthenon Publishing, Lancaster, UK. Bracken’s success is a response to the impact of man’s land use. A series of measurements throughout Britain show that average annual encroachment rates range from 0.65% to 3.3%. England has lost about 400 km² (an area equivalent of the Isle of Wight) to bracken. The majority of bracken occurs on slopes. It may pioneer new habitats, but more commonly occurs after natural deforestation or burning, reduction of predators or usually it occurs at the borders of agricultural land, especially in the marginal lands of Britain. A case for bracken control and the likely financial cost is given.
Taylor, J.A. (1988a) Bracken in the environment. Aspects of Applied Biology, 17 (1), 75-86. Since 1940, a continental climatic trend has reduced climatic constraints on the hillside bracken zone, leading to encroachment both up and down the hillside. There has been more intensive use of lowland pastures and heathland reclamation, allowing the slopes to revert to scrub. Sheep find bracken unpalatable and will not control it by grazing.
Taylor, J.A. (1988b) Annex 1: Bracken areas and encroachment rates in Wales. Bracken in Wales. The Senior Technical Officer’s Group, Wales, pp. 32-35. Nature Conservancy Council, Bangor, UK. In 1968, it was estimated that 5.7% of Wales was dominated by bracken. An encroachment rate of 1.2% is estimated in Wales, with an average rate of at least 1% per annum in upland Britain. Estimates of bracken area and expansion rates for Great Britain are given and compared to other land uses. Bracken encroachment may be regarded as a major land use change.
Taylor, J.A. (1995) Coming to terms with the bracken problem. Bracken: an environmental issue. International Bracken Group Special Publication No. 2 (eds. R.T. Smith & J.A. Taylor), pp. 1-11. University of Wales, Aberystwyth, UK. Bracken invades when woods that provided semi-shade, decline, and when farmland becomes under-used and under-managed. The extent of bracken may be underestimated on satellite imagery and be merged with rough grazing, but bracken encroachment rates are approximately 1% per annum nationwide, and may be up to 3% on common land. Figures for local and regional encroachment rates and projections into the 21st century are given.
Taylor, J.C., Bird, A.C. & Keech, M.A. (1991a) Landscape change in the National Parks of England and Wales. Final Report Vol. IX The North York Moors. Silsoe College, Bedford, UK. The project aimed to present information on the extent, distribution and change of a wide variety of landscape features in the North York Moors National Park, by the interpretation of aerial photographs from the 1970s and 1980s. The total areas of wood and forest, moor and heathland and agro-pastoral land all showed net increases over the time period. The problems of using aerial photo identification due to difficulties in interpretation of land classes are discussed.
217 Taylor, J.C., Bird, A.C. & Keech, M.A. (1991b) Landscape change in the National Parks of England and Wales. Final Report Vol. X The Peak District. Silsoe College, Bedford, UK. The project aimed to present information on the extent, distribution and change of a wide range of landscape features in the Peak District National Park, by the interpretation of aerial photographs from the 1970s and 1980s. The total areas of wood and forest and agro-pastoral land showed net increases over the period, whereas moor and heathland showed a net loss (sq km). The problems of using aerial photo identification due to difficulties in interpretation of land classes are discussed.
Taylor, J.C., Bird, A.C. & Keech, M.A. (1991c) Landscape change in the National Parks of England and Wales. Final Report Vol. XIII The Yorkshire Dales. Silsoe College, Bedford, UK. The project aimed to present information on the extent, distribution and change of a wide range of landscape features in the Yorkshire Dales National Park, by the interpretation of aerial photographs from the 1970s and 1980s. The total areas of moor and heathland and agro-pastoral land showed net decreases, whereas wood and forest areas showed net increases (sq km). The problems of using aerial photo identification due to difficulties in interpretation of land classes are discussed.
Taylor, J.C., Bird, A.C., Keech, M.A., & Stuttard, M.J. (1991) Landscape change in the National Parks of England and Wales. Final Report Vol. I Main Report. Silsoe College, Bedford, UK. The project aimed to present information on the extent, distribution and change of a wide variety of landscape features in the National Parks during the 1970s and 1980s. The report describes the methodology used and gives an assessment of the accuracy of the results. In all the Parks, the net total areas of wood and forest and agro-pastoral land increased, whilst moor and heathland decreased.
Thomas, D & Young, A. (1994) Upland breeding waders on Mynydd Hiraethog and Llandegla Moor, 1994. Unpublished report. RSPB, Sandy, Beds., UK. The uplands of Wales support nationally important numbers of several bird species, but numbers of breeding waders are declining. In the study area, the reasons for this decline are unclear, though land drainage and grassland improvement have been occurring.
Thomas, T.H., Harding, D.M., Hattey, R. & Martin, W. (1984) Agriculture, forestry and conservation in the hills and uplands of Wales: the need for an integrated approach. Hill Land Symposium (ed. M.A. O’Toole), pp. 508-544. Ballinrobe, Eire. Thirty-nine percent of Wales is officially designated ‘upland’. This paper describes the status of the major land use interests in the Welsh hills and uplands (farming, forestry and conservation) and how policy needs to be adjusted to meet all land uses.
Thompson, D.B.A., MacDonald, A.J., Marsden, J.H. & Galbraith, C.A. (1995) Upland heather moorland in Great Britain: a review of international importance, vegetation change and some objectives for nature conservation. Biological Conservation, 71, 163-178. Loss of heather moorland is occurring due to afforestation, agricultural reclamation, high grazing levels and bracken invasion. Classed as sub-montane, the lower limit of heather moorland is defined as the edge of enclosed agricultural land, usually around 300-400m in altitude.
Thompson, D.B.A., Stroud, D.A. & Pienkowski, M.W. (1988) Afforestation and upland birds: consequences for population ecology. Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 237-259. Blackwell Scientific Publications, Oxford, UK. Seventy-one species of birds are associated with uplands and at least 34 at risk from afforestation. Forests cause a greater abundance of common species and have an impact on species in unplanted areas.
Thompson, J., Mountford, E., Prestwood, W., Mills, E. & Jerram, R. (1999) Creating native woodland in upland England. English Nature Research Reports No. 307. English Nature, Peterborough, UK. The report is a practical follow-up to Research Report No. 230 and covers three project areas. In particular, the work in the Shropshire Hills examines native woodland creation at the upland-lowland fringe. In the Lake District, much of the woodland would be created on areas of bracken. The feasibility of creating new woodlands, existing policies and recommendations are discussed.
Thompson, T.R.E., Rudeforth, C.C., Hartnup, R., Lea, J.W. & Wright, P.S. (1986) Soil and slope conditions under Bracken in Wales. Bracken: ecology, land use and control technology (eds. R.T. Smith & J.A. Taylor), pp. 101-107. Parthenon Publishing, Lancaster, UK.
218 Bracken has a widespread distribution in Wales. This study shows that there is a strong relationship between bracken and the nature of the underlying soil. At present it occupies a relatively narrow range of soil and site conditions which are only a small part of its potential range.
Topp, C.F.E. (2000) Changing livestock and land use patterns: a case study - Loch Lomond 1945 to 1985. Aspects of Applied Biology, 58, 321-328. Since 1945, the structure of farming in the Loch Lomond area has changed, with a decline in dairy cattle and an increase in beef cattle and sheep. The area of cropping has declined significantly. Changes in agriculture have led to changes in vegetation and a reduction in farmland birds. Government and European Union policies which have influenced these changes are discussed.
Tudor, G.J. & Mackey, E.C. (1995) Upland land cover change in post-war Scotland. Heaths and moorland: cultural landscapes (eds. D.B.A. Thompson, A.J. Hester & M.B. Usher), pp. 28-42. HMSO, Edinburgh, UK. Between the 1940s and 1970s, there has been a reduction in upland semi-natural land cover due to an expansion of coniferous forestry, and conversion to semi-improved and improved grassland.
Tyler, S. (1988) Annex 5: Birds and bracken in Wales. Bracken in Wales. Senior Technical Officer’s Group, Wales, pp. 56-62. Nature Conservancy Council, Bangor, UK. Bracken is an important component of many Welsh woodlands and open hillsides or ffriddland. It may be important for providing shelter, nest sites and food sources for a range of species. Whinchats are the most dependent on ffridd. RSPB research shows gorse is the most important ffridd habitat, followed by bracken then semi-natural grassland. Trees and scrub increase the diversity of breeding birds.
Tyler, S. (1993) Yellow Wagtail. In: Gibbons, D,W., Reid, J.B. & Chapman, R.A. (eds.). The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991, pp286-287. T.& A.D.Poyser, London. Presents distribution and density maps of yellow wagtails breeding in Britain and Ireland. Data are derived from survey carried out between 1988 and 1991. Density maps indicate high densities of breeding yellow wagtails in parts of the northern Pennines.
Tyler, S.J. (1992) A review of the status of breeding waders in Wales. Welsh Bird Report, 5, 74-86.
Usher, M.B. & Gardner, S.M. (1988) Animal communities in the uplands: how is naturalness influenced by management? Ecological change in the uplands (eds. M.B. Usher & D.B.A. Thompson), pp. 75-92. Blackwell Scientific Publications, Oxford, UK. The faunas of three upland habitats are described and the effects of land management, such as drainage, burning and grazing detailed.
Usher, M.B. & Thompson, D.B.A. (1993) Variation in the upland heathlands of Great Britain: conservation importance. Biological Conservation, 66, 69-81. The mosaic structure of upland heathlands is critical for conservation and leads to greater invertebrate and vertebrate diversity. Management should include burning heathland margins less intensively and establishing scattered patches of scrub and woodland.
Vanhinsbergh, D.P. & Chamberlain, D.E. (2001) Habitat associations of breeding meadow pipits Anthus pratensis in the British uplands. Bird Study, 48, 159-172. A mosaic of heather, bog and grassland provides the optimum habitat for breeding meadow pipits. Recent changes in land management practices may have led to the disappearance or degradation of these mosaics in some areas. This species could be a bioindicator of changes in heather and grassland ratios that result.
Varvarigos, P. & Lawton, J.H. (1991) Farmers’ perceptions of the scale of the bracken problem on farms in Less Favoured Areas in England and Wales. Journal of Applied Ecology, 28, 988-1003. Bracken is a serious and increasing problem in upland Britain and is invasive of marginal land. LFA farmers in Wales estimate that bracken has declined by 1.8% during last 10 years, while English LFA farmers estimate an increase of 2.5%.
Wales Field Unit. (1982a) Upland Vegetation Survey. No. 9: Radnor Forest. Nature Conservancy Council, Gwynedd, UK. Findings of a vegetation survey of Radnor Forest SSSI and adjacent land carried out in 1981. The area is grazed by sheep but grazing pressure if fairly light. The vegetation of the survey area consists mainly of dwarf shrub
219 heath, blanket mire and some areas of acidic grassland. Forestry plantations and improved agricultural land separate the area from neighbouring hills.
Wales Field Unit. (1982b) Upland Vegetation Survey. No. 10: Gwaunceste-Glascwm-Rhulen Hill and Beacon Hill. Nature Conservancy Council, Gwynedd, UK. Results of a vegetation survey carried out in 1981, to define the botanical interest of two areas of Radnor. Vegetation consists mainly of dwarf shrub heath, though areas of bracken and acidic grassland are present on the steep slopes at the edge of the upland. Both areas are grazed by sheep and ponies.
Walker, C., Paskell, C., Hunter, D., Porley, R. & Phillips, G. (1983) Habitat loss in the Stiperstones area 1979- 82. Shropshire Trust for Nature Conservation, Shrewsbury, UK. In 1978/9, the Shropshire Trust carried out a survey of sites of value to wildlife. This was repeated in 1982. During this time 240 ha. of important wildlife habitat disappeared. Most of this was the result of agricultural improvement. The greatest loss occurred in ‘unimproved’ grassland with 22% of this habitat type being destroyed. Only a small amount of heathland and deciduous woodland was lost.
Walsh, A.L. and Harris, S. (1996) Foraging habitat preferences of vespertilionid bats in Britain. Journal of Applied Ecology, 33, 508-518.
Walters Davies, P. & Davis, P.E. (1973) The ecology and conservation of the red kite in Wales. British Birds, 66, 183-224, 241-270. Description of ffridd, which provides most of the food for the kite throughout the year. The paper gives a description of how changes in land use and current land management practices have affected the population.
Ward, S.D. (1972) The controlled burning of heather, grass and gorse. Nature in Wales, 13 (1), 24-32. Fire is commonly used to manage moorlands, upland grazings and rough areas of gorse and grass. Uncontrolled burning can result in changes in vegetation or soil erosion.
Wardhaugh, K.G., Mahon, R.J., Axelsen, A., Rowland, M.W. & Wanjura, W. (1993) Effects of ivermectin residues in sheep dung on the development and survival of the bushfly, Musca vetustissima Walker and a scarabaeine dung beetle, Euoniticellus fulvus Goeze. Veterinary Parasitology, 48, 139-157. The possible effects of antibiotic residues in sheep dung on the invertebrate fauna of grazed grassland are discussed. The adverse effects found were transient compared to those reported for cattle dung. Reducing invertebrate numbers can have serious consequences for dependent bird species.
Warren, M.S. (1995) Managing local microclimates for the high brown fritillary, Argynnis adippe. Ecology and Conservation of Butterflies (ed. A. S. Pullin), pp. 198-210. Chapman & Hall, London, UK. The high brown fritillary is now Britain’s most endangered butterfly. It breeds in bracken-dominated grassland on open but sheltered slopes. It’s decline may have been related to conifer planting replacing deciduous woodlands during the 1950s and 1960s. Trampling by livestock keeps the bracken from becoming totally dominant and breaks up the litter, which is advantageous for the butterfly larvae.
Warren, M.S. & Bourn, N.A.D. (1997) The impact of grassland management on threatened butterflies in ESAs. Grassland management in ESAs. BGS Occasional Symposium No. 32 (ed. R.D. Sheldrick), pp. 138-143. British Grassland Society, Reading, UK. A number of threatened fritillary butterflies breed in unimproved grassland with a covering of bracken, on marginal hill land. These include: high brown fritillary, pearl-bordered fritillary and small-pearl bordered fritillary. Agri-environment schemes have generally been successful in slowing the loss of unimproved grassland.
Warren, M.S. & Oates, M.R. (1995) The importance of bracken habitats to fritillary butterflies and their management for conservation. Bracken: an environmental issue. International Bracken Group Special Publication 2 (eds. R.T. Smith & J.A. Taylor), pp. 178-181. University of Wales, Aberystwyth, UK. Changes in forestry practice have affected butterfly numbers, notably high-brown, pearl-bordered and small pearl-bordered fritillaries. These species have become increasingly restricted to rough, scrubby grassland and certain bracken communities which exist on marginal grazing land in the hilly regions of western Britain. The heath fritillary now survives mainly on moorland fringes on Exmoor in association with bracken. Bracken seems to form a pseudo-woodland canopy, but grazing is required to provide canopy gaps and crush bracken litter.
220 Waterhouse, M. (1985) North Staffordshire Moors: survey 1985. Unpublished report. RSPB, Sandy, Beds., UK. A survey of the North Staffordshire Moors in 1985 counted 72 bird species of which 58 were breeding. Wet rushy fields provided the best habitat. Wet fields with higher grazing pressure had fewer species. Unimproved meadows are floristically rich but of no higher value to birds than improved hay meadows.
Wathern, P., Young, S.N., Brown, I.W. & Roberts, D.A. (1986) The EEC Less Favoured Areas Directive. Implementation and impact on upland land use in the UK. Land Use Policy, 3, 205-212. An analysis of the implementation of the LFA Directive, which provides support of agriculture in designated areas to sustain rural populations and protect the countryside. Grants and subsidies have led to deterioration of the upland landscape.
Wathern, P., Young, S.N., Brown, I.W. & Roberts, D.A. (1988) Recent upland land use change and agricultural policy in Clwyd, North Wales. Applied Geography, 8, 147-163. Description of post-war decline in upland rough grazing due to an increase in sheep numbers. Review of upland agricultural policy.
Whitehead, K. (1987) Agriculture and conservation in the hills and uplands (of the United Kingdom). Environmentalist, 7 (2), 148-150. Conference report on the future of the uplands. Ideas on making use of natural resources, especially if hill farming should decline.
Whitehead, S.J. & Digby, J. (1997a) The morphology of bracken (Pteridium aquilinum (L.) Kuhn) in the North York Moors - a comparison of the mature stand and the interface with heather (Calluna vulgaris (L.) Hull). 1. The fronds. Annals of Applied Biology, 131, 103-116. Bracken is successful in many diverse habitats, and shows a number of differences in growth form in response to the environment in which it is found. Established bracken forms a dense canopy and deep litter layers, which excludes many other plant species and is unattractive to many insect, bird and mammal species. Within the North York Moors, an estimated 28% of the total moorland area is dominated by bracken and continuing encroachment is a threat to areas of heather. Frond growth differs between bracken in a mature stand, at stationary stand margins, and at advancing stand margins where it is encroaching into heather.
Whitehead, S.J. & Digby, J. (1997b) The morphology of bracken (Pteridium aquilinum (L.) Kuhn) in the North York Moors - a comparison of the mature stand and the interface with heather (Calluna vulgaris (L.) Hull). 2. The rhizome. Annals of Applied Biology, 131, 117-131. The rhizome system of mature bracken contains large reserves of biomass and buds, which are responsible for its persistence and its rapid rates of vegetative encroachment. The area of the UK covered by bracken is increasing at an estimated 2% per annum, primarily due to the vegetative spread of rhizomes. Bracken rhizome morphology differs between a mature stand, a stationary stand margin and an advancing stand margin.
Whiteley, D. & Yalden, D.W. (1976) Small mammals in the Peak District. Naturalist, 938, 89-101. Information on small mammals in the Peak District has been collected by trapping, from owl pellets and bottles, and remains from road and predator casualties. Small rodents as a whole are scarce in the Peak District. Bank vole, field vole and pygmy shrew distributions reflect heavy grazing pressure and scarcity of scrub. Common shrew and wood mouse are more tolerant of barer ground. Bank voles are restricted to lower ground whereas pygmy shrew, field vole and wood mouse are all relatively common at higher altitudes.
Whitfield, P. (1996) Habitat requirements of breeding waders on blanket bogs in northern Scotland. Information and Advisory Note No. 53. Scottish Natural Heritage, Perth, UK. Breeding golden plover use pasture for feeding prior to dispersal to nesting areas. They continue to use these fields for feeding during incubation. They show strong site fidelity to a field, with large fields with a short sward and extensive cover of Juncus rushes being favoured. Those fields used for silage are not favoured. Dunlin also spend much of their time feeding on agricultural fields, in association with golden plover.
Whittingham, M.J., Percival, S.M. & Brown, A.F. (2000) Time budgets and foraging of breeding golden plover Pluvialis apricaria. Journal of Applied Ecology, 37, 632-646.
221 During incubation, golden plover feed mainly on enclosed fields up to 4 km from their moorland nests. Only 5% of foraging time is spent on moorland. Those with broods spent 85% of time foraging on moorland. The birds select calcareous grassland and avoid dense, taller vegetation.
Wightman, S. (2001a) Breeding wader surveys. Moorland research review 1995-2000 (eds. R. Charles, S. Wightman & M. Hammond), pp. 60-64. North York Moors National Park Authority, Helmsley, UK. Summarises results of breeding wader surveys from the North York Moors.
Wightman, S. (2001b) The habitat preferences of bird species nesting on moorland in the North York Moors National Park. Moorland research review 1995-2000 (eds. R. Charles, S. Wightman & M. Hammond), pp.65- 69. North York Moors National Park Authority, Helmsley, UK. Gives brief details of habitat preferences by birds breeding on moorland and hill-edge in the North York Moors.
Williams, G. & Green, R. (1993) Towards and upland habitat action plan. RSPB Conservation Review 7, pp. 5-11. RSPB, Sandy, Beds., UK. The uplands hold populations of at least 48 British Red Data bird species. Enclosed farmland on the margins of upland areas is also of considerable importance for birds, as these areas are usually farmed at a lower intensity than land in the lowlands. Changes in forestry and agriculture can have a considerable impact on bird populations.
Williams, I.T. (1996) The status of black grouse Tetrao tetrix in Wales in spring 1995 together with population changes since 1986. Welsh Birds, 1, 22-28. Presents data on status of black grouse in Wales.
Wilson, M.J., Bignal, E.M., Curtis, D.J., Drewitt, A.J. & Moos, C.J. (1991) The extent and distribution of low- intensity agricultural land in Britain. Birds and pastoral agriculture in Europe - Proceedings of the 2nd European forum on birds and pastoralism,, 26-30 October 1990 (eds. D.J. Curtis, E.M. Bignal & M.A. Curtis) pp. 25-31. Published on behalf of the Scottish Chough Study Group by JNCC, Peterborough. Summarises objectives and habitat recording methodology of the Low Intensity Agricultural Land (LIAL) project.
Wilson, A.M, Vickery, J.A. & Browne, S.J. (2001) Numbers and distribution of northern lapwings Vanellus vanellus breeding in England and Wales. Bird Study, 48, 2-17.
Woods, A. (1984) Upland Landscape Change: A Review of Statistics. Countryside Commission, Cheltenham, UK. The types of change occurring in the uplands are well documented, but information on their extent is less complete. Studies have found a net decline in the area of rough grazing since the last war. Afforestation was the major cause of this change, though agricultural reclamation was also responsible. Regional studies have shown that there have been small but widespread gains in the area of rough pasture due to reversion of improved agricultural land and deforestation. Some areas show a pattern of recurrent reclamation and reversion. The prediction of future trends may be difficult.
Wotton, S.R., Langston, R.H.W. & Gregory, R.D. (2002) The breeding status of the Ring Ouzel Turdus torquatus in the UK in 1999. Bird Study, 49, 26-34. The first co-ordinated census of breeding ring ouzels in the UK highlights a continuing contraction of range. A number of possible reasons for this decline have been put forward, but include changes in agricultural practices in the uplands. Most of the UK population remains in Scotland. Most nesting territories are found in moorland terrain but the birds fly to open moor or pasture to forage.
Yalden, D.W. (1972) The red grouse (Lagopus lagopus scoticus (Lath.)) in the Peak District. Naturalist, 922, 89-102. There is a general correlation between the distribution of grouse and heather, but grouse are also present where heather is absent. In these areas, bilberry provides the main food. Grouse bags have declined from 1940 onwards, which may be associated with a decline in number of gamekeepers, a decline in the extent of bilberry moors and an increase in sheep numbers.
Yalden, D.W. (1974) The status of golden plover (Pluvialis apricaria) and dunlin (Calidris alpina) in the Peak District. Naturalist, 930, 81-91.
222 Dunlin breed mainly in wetter areas of cottongrass but golden plover breeding is more widespread, occupying areas of cottongrass and patches of burnt Calluna and Empetrum-Vaccinium heath, where the vegetation is lower.
Yalden, D.W. (1986a) The further decline of black grouse in the Peak District 1975-1985. Naturalist, 111, 3- 8. The grouse have complex habitat requirements on the moorland fringes, needing pasture, moorland and scrubby woodland in a tight mosaic. This mosaic has remained in Staffordshire but has been replaced by a uniform habitat in Derbyshire. Examples of habitat change are given.
Yalden, D.W. (1986b) The status of golden plovers in the Peak Park, England in relation to access and recreational disturbance. Wader Study Group Bulletin, 46, 34-35. The golden plover is a typical moorland bird, but is sparsely distributed. The Peak District population is the southernmost viable population. There is evidence for a decline in the population in the Peak Park, in areas that receive the heaviest recreational use, such as Kinder. When disturbance was reduced, the breeding population increased.
Yalden, D.W. (1994) The changing status of red grouse Lagopus lagopus on peripheral moorlands in the Peak District. Naturalist, 119, 61-65. Between 1970 and 1990, red grouse numbers declined in the peripheral moorlands, probably due to changes in management. These changes include conversion of heather moorland to pasture, by tree planting and overgrazing by sheep.
Yorkshire Dales National Park Authority. (2000) Nature in the Dales. A biodiversity action plan for the Yorkshire Dales National Park. Yorkshire Dales National Park Authority, Skipton, UK. The document summarises the aims and objectives for biodiversity conservation in the National Park. The moorland fringe habitat is defined as the area dominated by marginal hill pastures and associated habitats between the improved enclosed pastures and the open moorland.
Yorkshire Dales National Park. (2001) Biodiversity Forum reaffirms commitment to Dales environment - 19 October 2001. http://www.yorkshiredales.org.uk/news/258.htm Details of a meeting to review the first year of the Biodiversity Action Plan for the Yorkshire Dales National Park - ‘Nature in the Dales’ - a ten year plan to protect and improve wildlife habitats, including the moorland fringe.
Younger, A. & Smith, R.S. (1993) Hay meadow management in the Pennine Dales, northern England. Grassland management and nature conservation. BGS Occasional Symposium No.28 (eds. R.J. Haggar & S. Peel), pp. 137-143. British Grassland Society, Reading, UK. Hay meadows contain a large number of species and are of conservation interest. The Pennine Dales ESA was established to protect this habitat from intensive farming.
223 APPENDIX 1.
Hill-edge habitat model: sensitivity analysis
Background
Sixteen landscapes within the North Peak and South West Peak ESAs were calculated within the model using LCM1990 with scopes at increasing spatial scales. The radii of the scopes used in this analysis ranged between 25m and 1000m (table A1.1). Two analyses were conducted examining the definition of the agricultural and moorland landscape components.
Table A1.1. Range of scopes, and two measures of the area they describe around the pixel of interest Scope (radius 25 50 75 100 125 150 175 200 225 250 300 375 450 500 750 1000 m) Number of pixels 5 13 29 49 81 113 149 197 253 317 441 709 1009 1257 2821 5025 within scope Area (ha) 0.3 0.8 1.8 3.1 5.1 7.1 9.3 12.3 15.8 19.8 27.6 44.3 63.1 78.6 1763 3141 within scope
Extent, location and composition of the agricultural landscape component
The extent and location of the agricultural landscape component is determined to define the optimum threshold for the lower boundary of hill-edge. This was defined as the threshold that ensured that at least 50% of the area of the agricultural landscape component was composed of habitats certain to represent agricultural practice. Ideally, this would have been defined against the independent phase 1 surveys available to the project. However, North Peak ESA had little intensive agricultural land within its boundary at the time of the phase 1 survey, and that present is highly fragmented. It was found that the spatial agreement between phase 1 and LCM1990 data set was too poor on such small and scattered parcels to allow an adequate analysis. Consequently the analysis measured the extent of the known agricultural land covers present within the LCM1990 data that appeared within the modelled agricultural component. Previous analysis suggested the threshold lay at a value between 30% and 40% of the landscape value maxima. Five values were chosen to span this range, 30% 32.5%, 35%, 37.5% and 40%. Thresholds were set at each of these values for each of the 16 landscapes calculated, and
226 the area of the known agricultural habitat classifications falling within each threshold value were obtained for each landscape. This was then expressed as a proportion of the total area falling within the agricultural landscape description.
Extent and location of the moorland landscape component
The extent and location of the moorland landscape component is modelled to define the optimum threshold for the upper boundary of hill-edge. The extent and spatial agreement between the moorland defined within the calculated model landscapes and the moorland described in the phase 1 data for North Peak ESA and South West Peak ESA were calculated with values, assuming thresholds of 57%, 60%, 63%, 66% and 70% of the numerical maximum for that landscape. Again, these thresholds were chosen as the result of previous extensive analysis. The area of modelled moorland landscape above the threshold values are calculated, as well as the area that was in direct spatial agreement with the descriptions of moorland from the phase 1 map.
For this two figures were needed. The first is a description of the how well the modelled moorland agrees with those phase 1 habitat types that we can be certain represents moorland habitats (certain moorland). The second represents that area of agreement between modelled moorland and those phase 1 habitat types that may possibly represent moorland (possible moorland). The surveyed habitats and their inclusion as components in the certain moorland or possible moorland categories are given in table A1.2 for the North Peak ESA and table A1.3 for the South West Peak ESA
Two indices were calculated from this data. The first represents the simple percentage of the phase 1 moorland landscape found to be in agreement with the modelled moorland landscape component. The second is a ratio between the area of the modelled moorland landscape that does not fall in a phase 1 habitat type thought to represent moorland and the area of modelled moorland that does fall in a Phase 1 habitat type thought to be moorland.
227 Table A1.2: Habitat classifications used in the Phase 1 survey of North Peak ESA and their use as descriptors of either agricultural, certain or possible moorland landscape components. Area Certain Possible Habitat type Agricultural (ha) Moorland moorland Acid flush 364.7 9 Amenity grassland 43.0 9 Bare ground 194.1 9 Bare peat 1128.7 99 Broad leaved plantation 401.3 Broad leaved semi natural woodland 354.0 Cliff 21.8 9 Coniferous plantation 2062.5 Continuous bracken 1678.0 9 Cotton grass moorland 5937.2 99 Dry bog heather dominated 6889.4 99 Dry bog non-heather dominant 4350.9 99 Dry dwarf shrub heath, heather 99 dominated 6678.6 Dry dwarf shrub heath, non-heather 99 dominated 4037.8 Eroding moorland 2363.4 99 Improved grassland 1149.8 9 Juncus dominated marshy grass 244.8 9 Mixed plantation 216.9 Mixed semi natural woodland 5.8 Molinia dominated grassland 3220.2 9 Open water 1034.9 Quarry 33.3 Recently felled coniferous plantation 18.0 Scree 101.3 9 Scrub 58.7 Semi-improved acid grassland 1040.4 Semi-improved acid rough pasture 485.9 Semi-improved neutral grassland 2898.1 Semi-improved neutral rough pasture 251.4 Short term ley grassland/Arable 465.2 9 Unimproved acid grassland 6355.5 9 Urban 610.6 Wet bog 3.6 99 Wet heath/acid grass 289.2 9
228 Table A1.3: Habitat classifications used in the Phase 1 survey of South West Peak ESA and their use as descriptors of either agricultural, certain or possible moorland landscape components. Area Certain Possible Habitat Agricultural (ha) moorland moorland Acid grassland 2673.6 9 Bilberry/crowberry moorland 832.4 99 Bracken 263.5 9 Cultivated land 767.2 9 Heather moorland 2836.7 99 Meadow & pasture 3202.2 9 Other 1304.2 Other moorland 550.1 99 Permanent grassland 17090.0 * Rough grazing 2036.6 Woodland 2282.4
Results
Agricultural landscape component
North Peak ESA
The North Peak ESA covers 54,979.5 ha. Within this lie part of the southern Pennine chain and includes well defined moorland areas. Agricultural areas are limited, with LCM1990 estimating known agricultural habitats to cover 2,594.8 ha whilst the Phase 1 map produces an estimate of certain agricultural cover of 1,614.9 ha using the habitat descriptions indicated in table A1.2. The landscape modelling exercise produces estimates of the agricultural landscape component ranging from 62.1 ha to 4404.6 ha. Whilst these two extremes were deliberately set to be outside sensible estimates for the extent of the agricultural landscape component they bracket the measured values.
The proportion of known agricultural land within the modelled landscape component decreases systematically with both increasing threshold values and increasing scope (Fig. A1.1). The slopes of both of these responses are steep compared to the same analysis within South West Peak ESA (Fig. A1.2) because of the closer proximity of distinct moorland and agricultural zones in the North peak ESA. As Figure A1.1 shows, at the largest threshold value (40%) those scopes above 125m do not achieve the target
229 proportion of half the land within the agricultural landscape component being of agricultural character.
90
80
70
Percentage 60 agreement
50
40
30 25 75 125 175 30% 225 300 35% 450 Scope (m) 32.50% Threshold value 750 40% 37.50%
Fig. A1.1: Response surface for a range of scope and threshold values showing the percentage of agricultural habitats within the modelled agricultural landscape component for North Peak ESA.
South west Peak South West Peak ESA covers 33,839.5 ha, and includes some relatively small ericaceous moorland areas. These become quite fragmented and it is less clear where moorland, hill- edge and agricultural landscapes are bounded. Agricultural habitats are measured by LCM1990 at 8,923.1 ha. The Phase 1 survey for South West Peak reports the agricultural habitats as 21,059.4 ha including “permanent grassland” or 3,969.4 ha excluding “permanent grassland”.
Though agricultural land is well represented in the South West Peak ESA and good agreement is achieved between model predictions of the agricultural landscape component and Phase 1 data, the Phase1 agricultural data is not used here to validate the predictions of the model. This is because the substantial area recorded as “permanent grassland” makes it difficult to differentiate between improved grasslands, which should be included as an agricultural land cover, and the less improved or rough grasslands which have received little or no improvement and should more properly be excluded as defining an intensive agricultural land cover. In addition, as a comparison with North Peak ESA was subsequently required the same types of comparisons were sought e.g. agricultural land as defined within LCM1990. The sensitivity analysis of the model predicts that the area of the agricultural landscape components ranges from 5,656.7 ha to 17,204.6 ha. The proportion of known agricultural
230 land within the modelled landscape component decreases systematically with both increasing threshold values and increasing scope (Fig A1.2) though less dramatically than at North Peak. As a result of this a greater proportion model predictions for any given scope or threshold value show that the modelled agricultural landscape component would contain over half of its area as potential agricultural habitats.
90
80 Percentage agricultural 70 habitat 60
50
40
30 25 75 125 175 225 30% Scope (m) 300 450 35% 32.50% Threshold value 750 40% 37.50%
Fig. A1.2: Response surface for a range of scope and threshold values showing the percentage of agricultural habitats within the modelled agricultural landscape component for South West Peak ESA.
Moorland landscape component – percentage agreement of Phase 1 surveys with modelled landscape
North Peak ESA According to LCM1990, moorland habitat types cover 19,217.4 ha though this includes only the ericaceous habitats and upland bog. The phase 1 estimates moorland cover to range from 31,373.1 ha for those phase 1 parcels of certain moorland character (table A1.1) to 43,806.1 ha for those phase 1 parcels of possible moorland character. The large difference between the estimates using habitats of certain moorland character between LCM1990 and the Phase 1 map is unsurprising. The phase 1 map is produced by surveyors who will ignore and subsume small patches of non-ericoid vegetation into large continuous parcels labelled as solely ericoid on the basis of a number of subjective assessments. The LCM1990 mapping does not do this and areas of ericoid moorland are rarely seen as continuous, and more commonly interspersed with a variety of other habitat types. The measured area of ericoid vegetation in the LCM1990 represents only 61.25% of the area measured as certain moorland vegetation by the phase 1 mapping exercise.
231 The area of the modelled moorland landscape component ranges from 14,917.0 ha to 35,937.1 ha. The surface representing the percentage agreement between the spatial locations of the modelled moorland and the phase 1 maps representing certain and possible moorland habitats across changing scopes and threshold values show similar forms. Levels of agreement vary from 61.3% to 94.2% (Fig. A1.3) for the comparison against certain phase 1 moorland habitat types. The agreement for the comparison with the possible phase 1 moorland habitat types is poorer ranging from 47.5% to 84.1% (not shown). Both response surfaces show best agreements at their lowest thresholds and at scopes of around 500m across most threshold values.
100
90
80 Percentage 70 agreement 60
50
40
30
20 25 75 125 175 57% 225 60% 300 63% 450 750
Threshold value66% Scope (m) 70%
Figure A1.3 Response surface at a range of threshold values and scopes for the percentage agreement between certain phase 1 moorland and the modelled moorland landscape component within North Peak ESA
South WestPeak ESA The Phase 1 survey of the South West Peak ESA reports only 4220.4 ha of certain moorland habitat or 7156.3 ha of possible moor habitats (see table A1.3 for habitats used in this description). Land Cover Map 1990 reports only 2958.2 ha of ericoid moorland within the ESA, representing 70.1% of the area of certain moorland identified during the Phase 1 study.
The landscape model predicts that the area of the moorland component ranges from 1445.7 ha to 5259.2 ha. The degree of agreement between the predicted scale and location of the ericoid habitats as part of the moorland landscape component and the actual parcels of ericoid vegetation in the Phase 1 survey are poorer than in North Peak
232 both for the measures against certain moorland (Fig. A1.4) and possible moorland. Percentage agreements range between 29.4% and 81.5% for the former comparison, and 18% and 55.2% for the latter comparison. This is a result of the small and scattered nature of the ericoid vegetation parcels the South West Peak ESA. Many of the patches of moorland vegetation are so small and isolated or immediately surrounded by agricultural practise that they loose their moorland character. Peak percentage agreements are seen at scopes between 100m and 350m for the comparisons with both certain and possible moorland habitats.
100
90
80
70 Percentage 60 agreement 50
40 30 20 25 75 125 175 57% 225 60% 300 Scope (m) 450 63% 750
Threshold 66%
values 70%
Figure A1.4. Response surface at a range of threshold values and scopes for the percentage agreement between certain phase 1 moorland and the modelled moorland landscape component within South West Peak ESA
Moorland landscape component – Model predictions and the ratio of agreement and disagreement with phase 1 surveys
North Peak ESA The ratio of the modelled landscape that does not cover phase 1 moorland against the area that does, is a useful measure of the quality of the model as it accounts for the unnecessary additional areas classified as moorland by the model which would include habitat types normally excluded from any definition of moorland. Ratios vary between 0.083 and 0.368 for the comparison between the model and certain phase 1 moorland habitats (Fig. A1.5) with lower ratios indicating a better spatial agreement between moorland model and phase 1 data. The latter figure indicates that over ѿ of the model predicted area lies away from certain moorland vegetation and this suggests a poor fit of
233 the model to the phase 1 data. The quality of the ratio based comparison between the model and possible phase 1 moorland habitats is better, though this is to be expected, as possible moorland represents a larger area within the ESA. Ratios range between 0.082 and 0.272. Best fits for both certain and possible Phase 1 moorland (lowest ratios) occur between scopes of 200m and 300m.
0.4
0.35
0.3 Ratio (incorrect0.25 / correct) 0.2
0.15
0.1
0.05
0 750 450 300 57% 225 175 125 75 Scope (m) 63% 25 Threshold value 70%
Figure A1.5. Response surface at a range of threshold values and scopes for the ratio of the area incorrectly estimated to be moorland against the area correctly estimated to be moorland within North Peak ESA
South West Peak ESA The response surface comparing the ratio of unsuccessful moorland landscape predictions against successful landscape predictions also shows a poorer fit compared with that of the North Peak ESA. Ratios range between 0.220 and 0.468 for the comparison with the certain Phase 1 habitat survey (Fig A1.6) and vary between 0.093 and 0.328 for the comparison with the more expansive possible moorland determined within the phase 1 survey.
234 0.7
0.6
0.5
0.4 Ratio 0.3
0.2
0.1 25 75
0 125 175
57% 225
60% 300 Scope (m) 63% 66% 450 Threshold value 70% 750
Figure A1.6. Response surface at a range of threshold values and scopes for the ratio of the area incorrectly estimated to be moorland against the area correctly estimated to be moorland within South West Peak ESA
Discussion
Comparison with Phase 1 mapping It is not possible to directly compare the area assigned as moorland within a landscape scale categorisation and the area noted as moorland type vegetation in a phase 1 survey. Firstly, those plant communities characteristic of moorland may fail the description in the landscape context because they are isolated or fragmented. Secondly, moorland in landscape terms may contain certain plant communities such as rough grassland, which will also appear in the hill-edge and agricultural landscape component.
The comparison must be two fold. One, as a comparison against a sub-set of plant community types which should represent certain moorland vegetation. Whilst we do not expect complete agreement these two data sets, on the basis that most moorland vegetation is in large moorland blocks, agreement should be good.
The second comparison is with a larger area representing possible moorland plant communities. This would include those plant communities, which may be present in
235 moorland but may also have a role elsewhere in addition to the certain core moorland communities. Generally, model fits were seen to improve as the comparison moved from phase 1 vegetation maps of certain moorland to those of possible moorland. The explanation for this is that many of the habitat types characterising certain moorland plant communities were fragmented in the landscape. Some were so isolated that they would not fall into any description of a moorland landscape. In addition, the parcels of continuous vegetative communities are mapped independently of their landscape context. A strip of Molinia dominated grassland running from the high moor down to the valley bottom, is mapped as single unit. It would attract differing descriptions as part of the landscape.
Unfortunately, when undertaking the phase 1 surveys, two different lists of plant communities were produced making direct comparison between the two impossible.
Choice of parameters for national scale model
The choice of parameters appears to depend on the wish to optimise the absolute agreement with phase 1 mapping or the relative (by ratio) agreement with phase 1 mapping. If the absolute agreement is paramount then the choice is reduced to a large scope of 500m to 750m and relatively low threshold values for the separation of the landscape components. If it is important to minimise the area of the model prediction for the moorland landscape component that is not supported by phase 1 mapping, then smaller scopes of around 150m to 300m and moderate threshold values appear the most productive. The choice of intermediate scopes and their optimum thresholds thus produces a balance between these opposed measures of model quality. We chose a scope setting of 250m as our main estimate, as this seemed to produce maps with well smoothed and accurately represented moorland landscapes. Once the scope was chosen, the optimum threshold settings for both the agricultural boundary with hill-edge and the moorland boundary with hill-edge were determined using polynomial regression. This resulted in the threshold values set out in table A1.4.
Landscape Landscape component above Threshold (as a percentage of component threshold landscape maxima) for upper below threshold boundary Agricultural Hill-edge 38.4% Hill-edge Grass moorland 57.2% Grass moorland Heather moorland 58.4%
As a measure of the error surrounding the choice of one central estimate, model landscapes with scopes of 200m and 375m (and their associated optimal threshold values) were calculated for a representative regions within the UK including Dartmoor, Exmoor, Brecon Beacon and the North York Moors. Although a quantitative analysis was not performed, the spatial agreement of the moorland and hill-edge predictions was remarkably consistent, and even across this range of scopes the model appears insensitive.
236 APPENDIX 2
Plant species list Latin name Common name Abies alba European Silver-fir Acer campestre Field Maple Acer pseudoplatanus Sycamore Achillea millefolium Yarrow Agrostis capillaris Common Bent Agrostis curtisii Bristle Bent Aira praecox Early Hair-grass Alchemilla spp. Lady’s mantle Allium ursinum Ramsons Alnus glutinosa Alder Alnus spp. Alders Alopecurus borealis Alpine Foxtail Antennaria dioica Mountain Everlasting Anthoxanthum odoratum Sweet Vernal-grass Anthyllis vulneraria Kidney Vetch Asplenium adiantum-nigrum Black Spleenwort Asplenium obovatum Lanceolate Spleenwort Asplenium ruta-muraria Wall-rue Asplenium septentrionale Forked Spleenwort Asplenium trichomanes Maidenhair Spleenwort Asplenium viride Green Spleenwort Athryium filix-femina Lady-fern Avenula pratensis Meadow Oat-grass Bellis perennis Daisy Betula nana Dwarf Birch Betula pubescens Downy Birch Betula spp. Birchs Blechnum spicant Hard-fern Brachypodium sylvaticum False Brome Briza media Quaking-grass Bromus hordeaceus ssp. hordaeceus Soft-brome Calluna vulgaris Heather Caltha palustris Marsh-marigold Campanula rotundifolia Harebell Cardamine pratensis Cuckooflower Carex binervis Green-ribbed Sedge Carex capillaris Hair Sedge Carex caryophyllea Spring-sedge Carex dioica Dioecious Sedge Carex echinata Star Sedge
237 Carex ericetorum Rare Spring-sedge Carex flacca Glaucous Sedge Carex hostiana Tawny Sedge Carex panicea Carnation Sedge Carex pulicaris Flea Sedge Carex rostrata Bottle Sedge Carex viridula ssp. oedocarpa Common Yellow-sedge Cerastium fontanum Common Mouse-ear Ceratocapnos claviculata Climbing Corydalis Circaea lutetiana Enchanter’s-nightshade Cirsium arvense Creeping Thistle Cirsium heterophyllum Melancholy Thistle Cirsium palustre Marsh Thistle Cladonia arbuscula Lichen species Cochlearia pyrenaica Pyrenean Scurvygrass Coeloglossum viride Frog Orchid Colchicum autumnale Meadow Saffron Conium maculatum Hemlock Conopodium majus Pignut Cornus suecica Dwarf Cornel Corylus avellana Hazel Crataegus monogyna Hawthorn Crepis paludosa Marsh Hawk’s-beard Cryptogramma crispa Parsley Fern Cynosurus cristatus Crested Dog’s-tail Cystopteris fragilis Brittle Bladder-fern Dactylis glomerata Cock's-foot Danthonia decumbens Heath-grass Danthonia decumbens Heath-grass Deschampsia cespitosa Tufted Hair-grass Deschampsia flexuosa Wavy Hair-grass Dicranum majus Moss species Digitalis purpurea Foxglove Draba incana Hoary Whitlowgrass Drosera rotundifolia Round-leaved Sundew Dryopteris dilatata Broad Buckler-fern Dryopteris spp. Buckler-ferns Empetrum nigrum Crowberry Epipactis atrorubens Dark-red Helleborine Erica ciliaris Dorset Heath Erica cinerea Bell Heather Erica tetralix Cross-leaved Heath Eriophorum spp. Cottongrasses Eriophorum angustifolium Common Cottongrass
238 Eriophorum vaginatum Hare’s-tail Cottongrass Euphrasia officinalis Eyebright Euphrasia vigursii Eyebright Fagus sylvatica Beech Festuca ovina Sheep’s-fescue Festuca rubra Red Fescue Festuca vivipara Viviparous Sheep’s-fescue Fraxinus excelsior Ash Galium palustre Common Marsh-bedstraw Galium saxatile Heath Bedstraw Galium sterneri Limestone Bedstraw Galium verum Lady’s Bedstraw Gentiana verna Spring Gentian Gentianella amarella Autumn Gentian Geranium robertianum Herb-Robert Geranium sanguineum Bloody Crane’s-bill Geranium sylvaticum Wood Crane’s-bill Geum urbanum Wood Avens Graphina pauciloculata Lichen species Graphina ruiziana Lichen species Gymnadenia conopsea Fragrant Orchid Gymnocarpium dryopteris Oak Fern Helianthemum nummularium Common Rock-rose Helictotrichon pratense Meadow Oat-grass Hippocrepis comosa Horseshoe Vetch Holcus lanatus Yorkshire-fog Homalothecium sericeum Moss species Hyacinthoides non-scripta Bluebell Hydrocotyle vulgaris Marsh Pennywort Hylocomium splendens Moss species Hymenophyllum spp. Filmy-ferns Hymenophyllum wilsonii Wilson’s Filmy-fern Hypericum linariifolium Toadflax-leaved St John’s-wort Hypnum cupressiforme Moss species Ilex aquifolium Holly Jamesionella autumnalis Liverwort species Juncus acutiflorus Sharp-flowered Rush Juncus articulatus Jointed Rush Juncus effusus Soft-rush Juncus squarrosus Heath Rush Juniperus communis ssp. communis Common Juniper Kobresia simpliciuscula False Sedge Koeleria macrantha Crested Hair-grass Larix spp. Larchs
239 Leontodon spp. Hawkbits Linum catharticum Fairy Flax Lolium perenne Perennial Rye-grass Lotus corniculatus Common Bird’s-foot-trefoil Lotus pedunculatus Greater Bird’s-foot-trefoil Luzula multiflora Heath Wood-rush Lychnis flos-cuculi Ragged-Robin Lysimachia nemorum Yellow Pimpernel Malus sylvestris Crab Apple Mentha aquatica Water Mint Mercurialis perennis Dog’s Mercury Minuartia verna Spring Sandwort Molinia caerulea Purple Moor-grass Nardus stricta Mat-grass Narthecium ossifragum Bog Asphodel Oxalis acetosella Wood-sorrel Pannaria sampaiana Lichen species Parmelia spp. Lichen species Parnassia palustris Grass-of-Parnassus Pedicularis sylvatica Lousewort Peltigera apthiosa Lichen species Phegopteris connectilis Beech Fern Picea abies Norway Spruce Picea sitchensis Sitka Spruce Pilosella officinarum (Hieracium pilosella) Mouse-ear-hawkweed Pinguicula vulgaris Common Butterwort Pinus spp. Pines Pinus sylvestris Scots Pine Plantago lanceolata Ribwort Plantain Plantago maritima Sea Plantain Pleurozium schreberi Moss species Poa annua Annual Meadow-grass Polemonium caeruleum Jacob’s-ladder Polygala amarella Dwarf Milkwort Polygala serpyllifolia Heath Milkwort Polygonatum multiflorum Solomon’s-seal Polygonatum verticillatum Whorled Solomon’s-seal Polygonum viviparum Alpine Bistort Polypodium vulgare Polypody Polytrichum commune Hair moss species Populus tremula Aspen Potentilla crantzii Alpine Cinquefoil Potentilla erecta Tormentil Primula farinosa Bird’s-eye Primrose
240 Primula vulgaris Primrose Prunella vulgaris Selfheal Prunus spinosa Blackthorn Pteridium aquilinum Bracken Quercus petraea Sessile Oak Quercus robur Pedunculate Oak Quercus spp. Oaks Ranunculus acris Meadow Buttercup Ranunculus flammula Lesser Spearwort Ranunculus repens Creeping Buttercup Rhinanthus minor Yellow-rattle Rhododendron spp. Rhododendrons Rhytidiadelphus spp. Moss species Rubus fruticosus Bramble (Blackberry) Rubus saxatilis Stone Bramble Rumex acetosa Common Sorrel Rumex acetosella Sheep’s Sorrel Salix cinerea Grey Willow Salix phylicifolia Tea-leaved Willow Salix spp. Willows Sanguisorba minor Salad Burnet Sanguisorba officinalis Great Burnet Saxifraga hirculus Marsh Saxifrage Saxifraga hypnoides Mossy Saxifrage Scabiosa columbaria Small Scabious Sedum anglicum English Stonecrop Sedum forsterianum Rock Stonecrop Selaginella selaginoides Lesser Clubmoss Sesleria caerulea (Sesleria albicans) Blue Moor-grass Sorbus aucuparia Rowan Sorbus porrigentiformis Whitebeam speci Sphagnum auriculatum Bog moss species Sphagnum capillifolium Bog moss species Sphagnum papillosum Bog moss species Sphagnum recurvum Bog moss species Stellaria uliginosa Bog Stitchwort Succisa pratensis Devil’s-bit Scabious Taxus baccata Yew Thlaspi caerulescens Alpine Penny-cress Thuja plicata Western Red-cedar Thymus polytrichus ssp. britannicus Wild Thyme Thymus polytrichus (Thymus praecox) Wild Thyme Thymus pulegioides Large Thyme Tilia cordata Small-leaved Lime
241 Tilia platyphyllos Large-leaved Lime Tilia spp. Limes Tortella torluosa Moss species Trichophorum cespitosum Deergrass Trientalis europaea Chickweed-wintergreen Trifolium pratense Red Clover Trifolium repens White Clover Trollius europaeus Globeflower Ulex europaeus Gorse Ulex gallii Western Gorse Ulex spp. Gorses Ulmus glabra Wych Elm Ulmus spp. Elms Umbilicus rupestris Navelwort Usnea spp. Lichen species Vaccinium myrtillus Bilberry Vaccinium oxycoccos Cranberry Vaccinium vitis-idaea Cowberry Veronica montana Wood Speedwell Viola lactea Pale Dog-violet Viola lutea Mountain Pansy Viola palustris Marsh Violet Viola riviniana Common Dog-violet Viola rupestris Teesdale Violet Wahlenbergia hederacea Ivy-leaved Bellflower
242 APPENDIX 3
Common land surveys relating to hill-edge
CEREDIGION DISTRICT Francis et al. (1990)
CL. 9 – Land near Devil’s Bridge. Grid ref: SN750750 Transitional – 75% hill-edge, 25% grass moor, minor % agricultural land. CL. 11 – Part of Cors Bwlch Y Baedd. Grid ref: SN708700 Transitional – 60% hill-edge, 15% agricultural land, 30% mix of grass moor and moorland CL. 25 – Land near Cwmsymlog. Grid ref: SN710830 Transitional – 60% hill-edge, 20% mix of grass moor and moorland, 10-15% agricultural land CL.26 – Land south-west of Plynlimon. Grid ref: SN740840 Transitional – 40% hill-edge, 45-50% grass moor, 15% agricultual land, 15% moorland CL. 42 – Henriw, Brynrhosau and Banc Bwa-Drain. Grid ref: SN730803 Transitional – mixture of hill-edge, agricultural land, and grass moor. Only 5-10% moorland CL. 43 – Talwrn (Mynydd Tregaron). Grid ref: SN748590 Transitional – 60% grass moor, 35% hill-edge, 10% moorland CL.62 – Bryn Brâs and Hen Riw, Ponterwyd. Grid ref: SN747797 Transitional – 50% hill-edge, 50% mix of grass moor and moorland CL.68 – Frongoch Farm and Sheepwalk. Grid ref: SN785670 Transitional – 30-40% hill-edge, the rest a mix of grass moor and moorland with only a very small proportion agricultural land CL. 72 – Llwyngarn Mountain or Y Garn. Grid ref: SN706568 100% Hill-edge CL.74 – Land north east of Cwmystwyth. Grid ref: SN840767 Transitional – 40% hill-edge, 60% grass moor CL.76 – Mynydd Ffynnon Wen, near Ponterwyd. Grid ref: SN724798 Transitional – 60% hill-edge, 40% mix of grass moor and moorland, 5% agricultural land CL.77 – Claerddu Sheepwalk, Teifi Pools. Grid ref: SN785680 Transitional – 50% hill-edge, 40% moorland, 20% grass moor and moorland mix CL.83 – Bryn Brâs (south). Grid ref: SN745794 Transitional – 70% hill-edge, 15% agricultural land, 15% grass moor and moorland mix CL.116 – Pond Yr Oerfa and Mynydd Ffynnon Wen. Grid ref: SN728798 Transitional – 40% hill-edge, 50% lake, 10% agricultural land CL.119 – Land near Devil’s Bridge. Grid ref: SN747763 Transitional – 80% hill-edge, 20% agricultural land CL.126 – Land near Tregaron. Grid ref: SN725623 100% hill-edge CL.143 – Land near Plynlimon. Grid ref: SN779834 Transitional – 30% hill-edge, 60% moorland, 10% grass moor CL.145 – Land around Carn Fflûr, north east of Tregaron. Grid ref: SN744620 95% hill-edge, 5% grass moor CL.149 – Part of Blaen Mwyro, Crug Gynon and other land. Grid ref: SN800640 Transitional – 30% hill- edge, 70% grass moor CL.150 – Part of Esgair Saeson, Tywi Forest. Grid ref: SN803606. Transitional – 60% hill-edge, 30% grass moor, 10% moorland CL.151 – Land near Drosgol, nant Y Moch. Grid ref: SN750888 Transitional – 40% hill-edge, 25% grass moor, 35% moorland CL.152 – Part of Graig Goch and Graig Ddu. Grid ref: SN810740 Transitional – 40% hill-edge, 50% moorland, 10% grass moor CL.154 – Pant Y Craf Sheepwalk, north east of Tregaron. Grid ref: SN727612 Transitional – 40% hill- edge, 40% grass moor, 20% moorland CL. old 7 – Trawsallt, Esgair Embor and Rhôsygafallt. Grid ref: SN770705 Transitional – 50% moorland, 30% grass moor, 20% hill-edge, <5% agricultural land CL. old 20 – Banc Melyn, 3 km east of Tregaron. Grid ref: SN712600 Transitional – 60% hill-edge, 40% agricultural land CL. old 38 – Esgair Fedwen and Waun Westad. Grid ref: SN720597 Transitional – 20% hill-edge, 50% moorland, 30% grass moor CL. old 43 – Three tracts of land east of Ysbyty Ystwyth. Grid ref: SN763703 Transitional – 50% hill-edge, 50% grass moor CL. old 71 – Rhos Gelli-Gron, Bryngwyn Bach and Garon Gron. Grid ref: SN730622. Transitional – 35% hill-edge, 30% moorland, 25% agricultural, 10% grass moor
243 CL. old 124 – Land on north side of Llyn Teifi and part of Lan Fraith. Grid ref: SN769683 Transitional – 80% hill-edge, 15% lake, 5% grass moor CL. old 195 – Part of Rhôs Gelligron, 5 km north east of Tregaron. Grid ref: SN730614 Transitional – 35% hill-edge, 35% moorland, 30% grass moor
MONTGOMERY DISTRICT Francis et al. (1989)
CL.46 – Nant Yr Hebog Common or Belan Hill. Grid ref: SN928842 95% hill-edge. 5% agricultural land CL.48 – Waen Cilgwyn Hill, south of Llanidloes. Grid ref: SN950795 100% hill-edge CL.84 – Land near Llyn Clywedog. Grid ref: SN880890 Transitional – 40% hill-edge, 35% moorland, 25% grass moor CL.93 – Esgair Ganol, south of Llangurig. Grid ref: SN875766 Transitional – 95% hill-edge, 5% grass moor CL.95 – Carn Y Groes, south east of Llangurig. Grid ref: SN885768 100% hill-edge CL. 96 – Esgair Y Graig. Grid ref: SN900768 Transitional – 45% hill-edge, 45% moorland and grass moor mix, 10% grass moor CL.99 – Esgair Dernol. Grid ref: SN905760 Transitional – 70% hill-edge, 30% moorland and grass moor mix
RADNOR DISTRICT Penford et al. (1990)
CL.1 – Hergest Ridge and Hanter Hill, Kington. Grid ref: SO255565 Transitional – 80% hill-edge, 20% moorland and grass moor mix CL.3 – Littlehill Common, east of Llanbister. Grid ref: SO145735 Transitional – 70% hill-edge, 30% moorland and grass moor mix CL.7 – Carneddau Hill. Grid ref: SO070550 Transitional – 45% hill-edge, 45% moorland and grassmoor mix, 10% agricultural land CL.9 – Twyn Y Garth, near Erwood. Grid ref: SO107438 Transitional – 95% hill-edge, 5% agricultural land CL.10 – Furrow Hill, north west of Presteigne. Grid ref: SO282666 Transitional – 60% agricultural land, 40% hill-edge CL.11 – Llandeilo Hill, Llanbedr Hill, Red Hill etc. Grid ref: SO130485 Transitional – 60% moorland, 40% hill-edge CL.12 – The Begwns, south west of Painscastle. Grid ref: SO155445 Transitional – 90% hill-edge, 10% moorland and grass moor mix CL.13 – Moel Dod, near Llanbadarn Fynydd. Grid ref: SO079770 Transitional – 85% hill-edge, 10% grass moor, 5% moorland and grass moor mix CL.15 – Coed Swydd, near Pen Y Bont. Grid ref: SO140645 Transitional – 90% hill-edge, 10% grass moor and moorland mix CL.16 – Rhosgoch Common, north east of Painscastle. Grid ref: SO197485 Transitional – 50% hill-edge, 50% agricultural land CL.18 – Litton Hill, north west of Presteigne. Grid ref: SO255665 Transitional – 70% hill-edge, 20% grass moor and moorland mix CL.19 – Rhosfallog, north east of Llanbister. Grid ref: SO130745 100% hill-edge CL.21 – Cefn Llanbister. Grid ref: SO115733 100% hill-edge CL.22 –Llanbister and Moelfre Hills. Grid ref: SO130775 100% hill-edge CL.23 – Ysgwd-Ffordd, north east of Abbeycwmhir. Grid ref: SO088733 Transitional – 50% hill-edge, 50% moorland and grass moor mix CL.24 – Old Race Course, west north west of Knighton. Grid ref: SO260733 100% hill-edge CL.25 – The Skreen, north of Erwood. Grid ref: SO098438 Transitional – 60% agricultural land, 40% hill- edge CL.26 – Bryngwyn and Newchurch Hill. Grid ref: SO195505 Transitional – 40% hill-edge, 40% moorland and grass moor mix, 20% agricultural land CL.27 – Disgwylfa Hill, south west of Kington. Grid ref: SO225515 Transitional – 75% hill-edge, 20% moorland and grass moor mix, 5% agricultural land CL.34 – Llandegley Rocks. Grid refs: SO140610 Transitional – 60% hill-edge, 20% moorland and grass moor mix, 20% agricultural land CL.36 – Land west of Wye Valley and north west of Rhayader. Grid ref: SN930710 Transitional – 50% hill- edge, 50% moorland CL.44 – Pen-Common Common, north west of Painscastle. Grid ref: SO140475 Transitional – 50% hill- edge, 50% moorland and grass moor mix CL.45 – Yr Allt, south west of Gladestry. Grid ref: SO194525 100% Hill-edge
244 CL.46 – Aberedw Hills, east of Builth Wells. Grid ref: SO090520 Transitional – 70% hill-edge, 30% moorland and grass moor mix CL.51 – Perthi Common, Llansantffraed in Elwel. SO093546 Transitional – 50% hill-edge, 50% agricultural land CL.52 – Milton Hill, south of Gladestry. Grid ref: SO240500 Transitional – 50% hill-edge, 50% agricultural land CL.53 – Weythel Common, west of Kington. Grid ref: SO240570 Transitional – 65% hill-edge, 35% agricultural land CL.75 – Cwmgwary Parish Turbary, north west of Pant Y Dǒr. Grid ref: SN943772 100% hill-edge
CARMARTHENSHIRE Penford et al. (1989)
CL.4 – Land near Pencader. Grid ref: SN504353 Transitional – 50% hill-edge, 20% agricultural land, 15% moorland, 15% grass moor CL.5 – Land near Talley. Grid ref: SN605307 Transitional – 55% agricultural land, 45% hill-edge CL.8 – Land near Lampeter. Grid ref: SN660491 Transitional – 50% hill-edge, 30% grass moor, 15% moorland, 5% agricultural land CL.14 – Black Mountain (part). Grid ref: SN655160 Transitional – 60% agricultural land, 40% hill-edge CL.15 – Black Mountain (part). Grid ref: SN680170 Transitional – 55% moorland, 40% hill-edge, 5% agricultural land CL.16 – Black Mountain (part). Grid ref: SN680180 Transitional – 40% moorland, 40% hill-edge, 20% grass moor CL.18 – Black Mountain. Grid ref: SN770200 Transitional – 60% hill-edge, 40% scattered moorland and grass moor CL.20 – Mynydd Llangyndeyrn. Grid ref: SN475133 Transitional – 50% hill-edge, 50% agricultural land CL.27 – Garn Goch. Grid ref: SN690243 Transitional – 60% hill-edge (centre of area), 40% agricultural land (surrounding) CL.31 – Cors Farlais. Grid ref: SN678349 Transitional – 50% hill-edge, 40% moorland, 10% agricultural land CL.32 – Banc Du or Bank Cefngarreg. Grid ref: SN830390 Predominantly hill-edge, 5% moorland and grass moor mix CL.33 – Quarry Mountain. Grid ref: SN494285 Transitional – 50% hill-edge, 50% agricultural CL.34 – Betws Mountain. Grid ref: SN675110 Transitional – 50% hill-edge, 50% moorland and grass moor mix CL.47 – Cors Farlais. Grid ref: SN676349 Transitional – 60% hill-edge, 30% moorland and grass moor mix, 10% agricultural land CL.50 – Mynydd Bach. Grid ref: SN500287 Transitional – 50% hill-edge, 35% agricultural land, 15% moorland CL.51 – Penygarn. Grid ref: SN573316 Transitional – 55% hill-edge, 45% moorland CL.61 – Mynydd Crugmelyn (part). Grid ref: SN499267 Transitional – 55% agricultural land, 45% hill-edge CL.62 – Banc Cefn Garreg. Grid ref: SN833393 Predominantly hill-edge, 5-10% agricultural land CL.65 – Mynydd Mallaen (part). Grid ref: SN713413 Transitional – 60% hill-edge, 40% grass moor CL.66 – Mynydd Mallaen (part). Grid ref: SN726408 100% hill-edge CL.67 – Mynydd Mallaen (part). Grid ref: SN750426 Transitional – 60% hill-edge, 40% agricultural land CL.76 – Mynydd Ystyfflan. Grid ref: SN470264 Transitional – 50% hill-edge, 30% agricultural land, 20% moorland CL.80 – Figyn. Grid ref: SN555301 Transitional – 75% hill-edge, 20% agricultural land, 5% grass moor CL.82 – Figyn Fach. Grid ref: SN563308 Predominantly hill-edge, 5% agricultural land
245 CL.86 – Foel-Deg-Ar-Bedol (Black Mountain). Grid ref: SN700160 Transitional – 45% hill-edge, 45% moorland, 10% agricultural land CL.87 – Foel-Deg-Ar-Bedol (Black Mountain). Grid ref: SN705149 Predominantly hill-edge, 5% moorland CL.88 – Craig Derlwyn (Black Mountain). Grid ref: SN718154 Transitional – 50% hill-edge, 50% moorland CL.89 – Foel-Deg-Ar-Bedol (Black Mountian). Grid ref: SN730150 Transitional – 70% hill-edge, 20% agricultural land, 10% moorland CL.91 – Twyn Ymoch (Black Mountain). Grdi ref: SN750147 Transitional – 60% hill-edge, 30% agricultural land, 10% moorland CL.98 – Mynddystyfflau Carn. Grid ref: SN470268 Transitional – 60% moorland, 35% hill-edge, 5% agricultural land CL.110 – Bryn Dafydd. Grid ref: SN568312 Transitional – 60% agricultural land, 40% hill-edge CL.123 – Mynydd Figyn (part). Grid ref: SN588300 Transitional – 50% hill-edge, 50% agricultural land CL.125 – Gaeo Common (part). Grid ref: SN687470 Transitional – 75% hill-edge, 25% agricultural land CL.130 – Part of Black Mountain. Grid ref: SN690192 Transitional – 50% hill-edge, 50% agricultural land CL.144 – Black Mountain. Grid ref: SN761210 100% hill-edge
246