SKOMER ISLAND MANAGEMENT PLAN VEGETATION MIKE ALEXANDER First version January 2014 Complete revision and restructure October 2020 Dates of next reviews All projects require an annual review. A full review of the description and objective - 2030. i ii CONTENTS Introduction ......................................................................................................................................... 1 1. Legislation and Policy .................................................................................................................. 2 2. Description .................................................................................................................................. 3 Sources of information: ................................................................................................................... 4 Structure .......................................................................................................................................... 5 Maritime cliff and crevice community ............................................................................................. 8 Bird Cliff community ...................................................................................................................... 12 Coastal rocky slopes....................................................................................................................... 15 Sea cliff grasslands ......................................................................................................................... 15 Maritime, dry and wet heath ......................................................................................................... 37 Grasslands of the central fields ..................................................................................................... 45 Bracken .......................................................................................................................................... 54 Scrub, shrubs and trees ................................................................................................................. 68 Streams and associated wetlands, including ponds, marshy grassland and stream edges .......... 78 Miscellaneous ................................................................................................................................ 84 Rare higher plants and ferns.......................................................................................................... 91 3. Factors ....................................................................................................................................... 94 Environmental factors ....................................................................................................................... 94 Seabirds ......................................................................................................................................... 94 Salt spray........................................................................................................................................ 94 Soils ................................................................................................................................................ 95 Grazing by domestic animals ........................................................................................................... 100 Rabbits ............................................................................................................................................. 102 Rabbit control .............................................................................................................................. 104 The impact of rabbits on Skomer. ............................................................................................... 106 Introductions and bio-security ........................................................................................................ 109 Rosebay willowherb, Chamerion angustifolium .......................................................................... 111 The factors which have influenced heath on Skomer. ................................................................ 113 4. Features - Evaluation .............................................................................................................. 117 Conclusion ................................................................................................................................... 119 iii 5. Management Option ............................................................................................................... 120 Conclusion: .................................................................................................................................. 121 6. Objective for vegetation on Skomer ....................................................................................... 122 Vision: .......................................................................................................................................... 122 Performance indicators ............................................................................................................... 122 Surveillance. ................................................................................................................................. 123 Fixed point photography surveillance................................................................................... 123 Permanent vegetation quadrats ............................................................................................ 123 Record significant damage to vegetation ............................................................................. 124 New potentially invasive or threatening species ................................................................ 125 Rabbit surveillance. .................................................................................................................. 125 7. Management Rationale .......................................................................................................... 127 The key factors ............................................................................................................................. 127 8. Project descriptions ................................................................................................................ 130 RF00/01 Commission low-level, high-resolution aerial photography. ........................................ 130 RF00/02 Record Permanent vegetation quadrats. ...................................................................... 134 RF00/03 - Photographic Vegetation surveillance ........................................................................ 136 RF00/04 Record significant damage to the vegetation ............................................................... 138 RF20/01 Map the distribution of species .................................................................................... 140 RF 20/02 New potential invasive species .................................................................................... 141 RF 20/03 Surveillance – rare higher plants and ferns (SSSI) ........................................................ 142 RF 20/04 Surveillance – rare higher plants and ferns not-sssi features ...................................... 145 RF20/03 Bracken invading Puffin colonies .................................................................................. 147 RF20/04 Map Ragwort ................................................................................................................. 148 RF20/05 Bramble ......................................................................................................................... 149 MS01/01 Control rosebay willowherb Chamerion angustifolium ............................................... 150 References .......................................................................................................................................... 153 iv INTRODUCTION The original, 2014, vegetation plan was intended for consultation and discussion, there was an emphasis on asking questions and avoiding conclusions. The document did not follow the logic and structure of a management plan. This version is a complete rewrite with significant additional material. It is compliant, as far as appropriate, or necessary, with the Wildlife Trust of South and West Wales and Natural Resources Wales management plan guidelines. This plan will be a public document available to anyone with an interest in Skomer. Some readers may not be familiar with some of the terminology or plan concepts, explanations and background information will be included in the text. The Vegetation section will include: • A detailed description of the vegetation, this will include comment on their history and the factors which had a specific impact on the development of the individual communities. • The key factors (influences), past and present, with an emphasis on the future, are described and discussed. • The conservation objective with associated monitoring/surveillance and recording projects. • A management rationale and outline action plan. The organisation of a plan for a protected site is usually based on the presence of statutory features; the WTSWW plan also includes an evaluation or rationale which identifies other key, but non- statutory, features. A feature is quite simply something which is sufficiently important in the context of the site to merit specific attention in the management plan. Once features