Guidelines for the selection of biological Areas of Special Scientific Interest (ASSIs) on the Isle of Man Volume 2: Detailed habitat and species criteria Volume 2 Detailed habitat and species criteria Introduction The following chapters describe natural and semi-natural vegetation communities on the Isle of Man, their relationship to established methods of classification such as the National Vegetation Classification, characteristics that will be taken into consideration when assessing a potential ASSI, and minimum criteria for selection. Where a habitat is rare or locally distributed on the Island, the most important known sites may be listed individually. The habitat selection criteria are followed by criteria for site selection based on the presence of important species from a range of plant and animal groups. It should be noted that in many cases a site will qualify on both habitat and species grounds. Both the habitat and species chapters contain an indication of the current level of knowledge about the subject. Where knowledge is limited, e.g. for some invertebrate and lower plant groups, there is an assessment of research needs and priority level. Where there is a choice of several sites with the same important habitats or species present and a choice needs to be made about which site to select, the relative quality of the sites will be assessed using the Priority Sites Criteria in Part 3 of Volume 1. Chapter index to Detailed Guidelines Chapter pages: 4.1 Woodland and scrub 1 4.2 Lowland grasslands 22 4.3 Lowland heathland 43 4.4 Bogs, fens and flushes 54 4.5 Open water and swamp 65 4.6 Coastal habitats 78 4.7 Uplands 104 4.8 Flora 126 4.9 Avifauna (birds) 127 4.10 Fauna (all other animals) 133 Please note that in order to avoid duplication of habitat accounts some chapters – e.g. Upland habitats - may refer to sections of other chapters. Guidelines for the selection of biological ASSIs Volume 2 i DAFF, January 2008 Contents Introduction ..................................................................................................................................................................... i Part 4: Detailed selection guidelines .................................................................................................................................... 1 4.1 Woodland and scrub ...................................................................................................................................................... 1 4.1.1 Semi-natural broadleaved woodland ...................................................................................................................... 6 Minimum selection criteria for semi-natural broadleaved woodland ........................................................................... 7 Table 4.1.a: Broad categories of semi-natural woodland on the Isle of Man .............................................................. 8 4.1.2 Plantations ........................................................................................................................................................... 10 Table 4.1.b: Broad categories of plantation on the Isle of Man ................................................................................ 11 Minimum selection criteria for plantations ................................................................................................................ 12 4.1.3 Dry scrub ............................................................................................................................................................. 13 Table 4.1.c: Broad categories of dry scrub on the Isle of Man ................................................................................. 14 Minimum selection criteria for dry scrub ................................................................................................................... 16 4.1.4 Curragh ................................................................................................................................................................ 16 Minimum selection criteria for curragh ..................................................................................................................... 17 Appendices to Chapter 4.1: Diagnostic species lists ...................................................................................................... 18 Appendix A: Tree and shrub species thought to be native to the Isle of Man .......................................................... 18 Appendix B: Woodland ground flora species associated with semi-natural woodland .............................................. 19 Appendix C: Plants not of native origin which may indicate unfavourable condition ................................................ 21 4.2 Lowland grasslands ...................................................................................................................................................... 22 4.2.1 Acid grasslands .................................................................................................................................................... 24 Minimum selection criteria for lowland acid grassland .............................................................................................. 25 Table 4.2.a: Broad categories of acid grassland on the Isle of Man ......................................................................... 26 4.2.2 Neutral grasslands ................................................................................................................................................ 27 Minimum selection criteria for neutral grassland ...................................................................................................... 28 Table 4.2.b: Broad categories of neutral grassland on the Isle of Man..................................................................... 29 4.2.3 Calcareous grasslands .......................................................................................................................................... 31 Table 4.2.c: Broad categories of calcareous grassland on the Isle of Man ............................................................... 32 Minimum selection criteria for calcareous grassland ................................................................................................. 33 4.2.4 Coastal grassland ................................................................................................................................................. 33 Table 4.2.d: Broad categories of coastal grassland on the Isle of Man ..................................................................... 35 Minimum selection criteria for coastal grassland ...................................................................................................... 36 Table 4.2e: Vascular plants characteristic of semi-natural grassland on the Isle of Man .......................................... 37 4.3 Lowland heathland ....................................................................................................................................................... 43 4.3.1 Dry lowland heathland ......................................................................................................................................... 48 Table 4.3.a: Broad categories of dry lowland heathland on the Isle of Man ............................................................. 49 Minimum selection criteria for dry lowland heathland .............................................................................................. 49 4.3.2 Wet lowland heathland ........................................................................................................................................ 50 Table 4.3.b: Broad categories of wet lowland heathland on the Isle of Man ............................................................ 50 Minimum selection criteria for wet lowland heathland .............................................................................................. 51 4.3.3 Coastal heathland ................................................................................................................................................ 51 Table 4.3.c: Broad categories of coastal heath on the Isle of Man ........................................................................... 52 Minimum selection criteria for coastal heathland ...................................................................................................... 53 4.4 Bogs, fens and flushes ................................................................................................................................................. 54 4.4.1 Bog ...................................................................................................................................................................... 56 Table 4.4a: Broad categories of bog on the Isle of Man ........................................................................................... 59 Minimum selection criteria for bogs .......................................................................................................................... 59 4.4.2 Valley mires and flushes ....................................................................................................................................... 60 Minimum selection criteria for valley mires and flushes ............................................................................................ 61 4.4.3 Basin mires..........................................................................................................................................................