DOCTORAL THESIS Plant ecology of lowland Alnus Glutinosa woodlands The management implications of species composition, requirements and distribution Helen Miller If you have discovered material in AURA which is unlawful e.g. breaches copyright, (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our takedown policy at http://www1.aston.ac.uk/research/aura/aura-take-down-policy/ and contact the service immediately [email protected]. PLANT ECOLOGY OF LOWLAND ALNUS GLUTINOSA WOODLANDS: THE MANAGEMENT IMPLICATIONS OF SPECIES COMPOSITION, REQUIREMENTS AND DISTRIBUTION HELEN SONYA MILLER Doctor of Philosophy ASTON UNIVERSITY January 2012 © Helen Sonya Miller, 2012. Helen Sonya Miller asserts her moral right to be identified as the author of this thesis This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without proper acknowledgement. 1 ASTON UNIVERSITY PLANT ECOLOGY OF LOWLAND ALNUS GLUTINOSA WOODLANDS: THE MANAGEMENT IMPLICATIONS OF SPECIES COMPOSITION, REQUIREMENTS AND DISTRIBUTION HELEN SONYA MILLER Doctor of Philosophy January 2012 Wet woodlands have been recognised as a priority habitat and have featured in the UK BAP since 1994. Although this has been acknowledged in a number of UK policies and guidelines, there is little information relating to their detailed ecology and management. This research, focusing on lowland Alnus glutinosa woodlands, aimed to address this data paucity through the analysis of species requirements and to develop a methodology to guide appropriate management for this habitat for the benefit of wildlife. To achieve these aims data were collected from 64 lowland Alnus glutinosa woodlands and a review of the literature was undertaken to identify species associated with the target habitat. The groundflora species found to be associated with lowland Alnus glutinosa woodland were assessed in relation to their optimal environmental conditions (Ellenberg indicator values) and survival strategies (Grime CSR-Strategy) to determine the characteristics (Characters of a Habitat; CoaHs) and range of intra-site conditions (Niches of a Habitat; NoaH). The methodologies, using CSR and Ellenberg indicator values in combination, were developed to determine NoaHs and were tested both quantitatively and qualitatively at different lowland Alnus glutinosa sites. The existence of CoaHs and NoaHs in actual sites was verified by detailed quadrat data gathered at three Alnus glutinosa woodlands at Stonebridge Meadows, Warwickshire, UK and analysed using TWINSPAN and DCA ordination. The CoaHs and NoaHs and their component species were confirmed to have the potential to occur in a particular woodland. Following a literature search relating to the management of small wet woodlands within the UK, in conjunction with the current research, broad principles and strategies were identified for the management of lowland Alnus glutinosa woodland. Using the groundflora composition, an innovative procedure is developed and described for identifying the potential variation within a particular site and determining its appropriate management. Case studies were undertaken on distinct woodlands and the methodology proved effective. Key words: Riparian. Groundflora. Ellenberg. CSR. Wet. 2 DEDICATION I would like to dedicate this thesis to Andy who sadly passed away a few days after my viva, although he will remain a constant source of inspiration, enthusiasm and motivation. ACKNOWLEDGEMENTS The following organisations and people are gratefully acknowledged for their help and support at various times during this research and without their willing assistance it could not have been completed. Middlemarch Environmental Ltd and Aston University provided the opportunity to undertake this research and without them I could not even have started. It was also through them that I was able to attend and present a paper at the Nutrient Cycling and Retention in Natural and Constructed Wetlands V Conference in the Czech Republic. I should like to thank Bedfordshire Wet Woodland Group and everyone who took the time to answer my questionnaire developed at the beginning of this research. Through them I was able to focus the original objectives. Access to sites and use of associated floristic data from the following organisations was critical: Worcester Wildlife Trust; Warwickshire Wildlife Trust (especially Eddie); Leicester & Rutland Wildlife Trust; Hereford Wildlife Trust; Hertfordshire Wildlife Trust; South Yorkshire Wildlife Trust; Derbyshire Wildlife Trust Solihull Metropolitan Borough Council; British Airways. Statistical analysis guidance from Reading University Plant Science Department and Alison and Lynn at Wolverhampton University was very much appreciated. Adrien saved me a lot of tedium by willingly measuring the soil moisture of 278 quadrats. Permission to use research undertaken by the author, under a Middlemarch Environmental Ltd contract, was kindly given by Severn Trent Water and National Forest. Chapters 2 and 8, in particular, draw upon work completed for these two companies. Without Lynn’s guidance and belief over the last year, this thesis would not have come together. And last but certainly not least I should like to recognise the invaluable support given by my friends and family, especially Diana, David, Andy and Derek, along with former colleagues at the Forestry Commission with whom I have mulled over many ideas over the years. 3 LIST OF CONTENTS LIST OF TABLES, FIGURES AND EQUATIONS................................................ 7 Tables ............................................................................................................ 7 Figures........................................................................................................... 13 Equations....................................................................................................... 20 LIST OF TERMS........................................................................................................ 20 1. INTRODUCTION................................................................................................... 23 1.1 Origins of Project .......................................................................................... 23 1.2 Aims and Objectives of Research Project..................................................... 24 1.3 Thesis Structure............................................................................................. 25 2. LITERATURE REVIEW....................................................................................... 28 2.1 Defining the Habitat...................................................................................... 28 2.2 Importance of Woodlands............................................................................. 34 2.3 Diversity of Woodland.................................................................................. 47 2.4 Management for Nature Conservation.......................................................... 63 2.5 Factors that Influence the Management of Wet Woodland for Nature Conservation ................................................................................................. 67 2.6 Effects and Implications of Management on Woodland Characteristics...... 74 2.7 Management Techniques.............................................................................. 82 2.8 Conclusions................................................................................................... 93 3. DEVELOPMENT OF RESEARCH METHODOLOGY AND 95 JUSTIFICATION ...................................................................................................... 3.1 Determining Species Occurring in Lowland Alnus glutinosa Woodland ..... 95 3.2 Species Potentially Endemic to Lowland Alnus glutinosa Woodland.......... 99 3.3 Theoretical Environmental Characteristics of Lowland Alnus glutinosa Woodland ...................................................................................................... 102 3.4 Theoretical Niches of a Habitat (NoaHs)...................................................... 112 3.5 Detailed Vegetation Study ............................................................................ 125 3.6 Verifying the Occurrence of Niches of a Habitat – Lowland Alnus glutinosa Woodland ...................................................................................... 128 3.7 Developing a Management Decision Tool.................................................... 130 4. DEFINING CHARACTERISTICS OF LOWLAND ALNUS GLUTINOSA 132 WOODLAND .............................................................................................................. 4.1 Introduction and Aims of Chapter................................................................. 132 4.2 Geographic and Spatial Location.................................................................. 132 4.3 Species Occurring in Alnus glutinosa Woodland.......................................... 132 4.4 Species Potentially Endemic to Alnus glutinosa Woodland ......................... 133 4.5 Theoretical Environmental Characteristics of Alnus glutinosa Woodland... 136 4.6 Discussion on Defining the Characteristics of Lowland Alnus glutinosa Woodland .....................................................................................................