Fens Biodiversity Audit Cover photos: Wodwalton Fen, Steven Falk Ouse Washes, Wildlife Trust BCN A rare reed beetle, Plateumaris braccata , Brian Eversham A wetland soldier beetle, Silis ruficollis , Brian Eversham Orb-web Spider, Araneus marmoreus , Brian Eversham Fen Violet, Brian Eversham Fen Ragwort, Brian Eversham A wetland ground beetle, Chlaenius vestitus , Brian Eversham Hoverfly, Tropida scita , Brian Eversham Dactylorhiza incarnata ssp. ochroleucon , Peter Walker Fens Biodiversity Audit Part 1 & 2 - Methodology and Results H.L. Mossman, C.J. Panter, P.M. Dolman School of Environmental Sciences, University of East Anglia, Norwich Acknowledgements This work was carried out in conjunction with the Cambridgeshire and Peterborough Environmental Records Centre (CPERC) and Bedfordshire, Cambridgeshire and Northamptonshire Wildlife Trust. The work was funded by Natural England, Environment Agency, National Trust, Cambridgeshire & Peterborough Biodiversity Partnership and the Norfolk Biodiveristy Partnership. We are very grateful to the members of the Fens for the Future Steering Group for their advice and support. We are indebted to Charlie Barnes, Rosie Blackman, Jon Cole, Brian Eversham, Annette Faulkner, Ian Dawson, Martin Horlock, Peter Kirby, Nick Millar, Nick Owens, Val Perrin, Ivan Perry, John Showers, David Sheppard, Alan Stubbs and Jon Webb. We are also very grateful to the many other individuals who provided invaluable help, including biological records, autecological information, and information on management outcomes, without these generous contributions this work would not have been possible. In particular we acknowledge the information and expertise provided by site managers critical to preparation of part 3 of the report. We also acknowledge the invaluable contributions of many hundreds of additional recorders and members of the public who over many years have submitted information to the Local Records Centres, county and national taxonomic recording schemes, or NBN. 1 Contents Part 1 - Methodology .................................................................................................................... 4 Study area ................................................................................................................................. 4 Data collation ............................................................................................................................ 6 Database refinement ................................................................................................................ 6 Cut-off date ............................................................................................................................... 7 Data mapping and analysis ....................................................................................................... 7 Definition of conservation priority species ............................................................................... 7 Definition of Fens Specialist species ......................................................................................... 8 Expert stakeholder validation of collated priority taxa .......................................................... 10 Extinct and extirpated taxa ..................................................................................................... 11 Collating and synthesising species habitat associations and ecological requirements .......... 12 Habitat associations ............................................................................................................ 12 Ecological structures and processes ................................................................................... 13 Sources of ecological information ...................................................................................... 13 Part 2 - Results ............................................................................................................................ 14 Biodiversity in the Fens ........................................................................................................... 14 Recording coverage ............................................................................................................ 14 Distribution of biodiversity in the Fens .............................................................................. 15 Fen Regional Specialists .......................................................................................................... 23 Extinctions in the Fens ............................................................................................................ 27 Habitat Associations ............................................................................................................... 31 Key habitats for Priority Biodiversity .................................................................................. 31 Key habitats for Fens Specialists ......................................................................................... 31 Guild Analysis ...................................................................................................................... 34 Successional and hydrological conditions .......................................................................... 34 Classification of management guilds .................................................................................. 35 Management guilds ................................................................................................................ 41 Guild Descriptions ................................................................................................................... 44 1. Broad guild: Open – Fast-flowing Water ........................................................................ 44 2. Broad guild: Open – Aquatic ........................................................................................... 44 6. Broad guild: Open – Submerged margins ....................................................................... 47 11. Broad guild: Open woodland – Aquatic ........................................................................ 48 12. Broad guild: Open – Littoral .......................................................................................... 48 18. Broad guild: Scattered scrub – Littoral – Sward mosaics.............................................. 49 19. Broad guild: Open – Terrestrial littoral ......................................................................... 50 24. Broad guild: Closed-canopywood/scrub – Littoral ....................................................... 53 25. Broad guild: Open to closed-canopy – Littoral ............................................................. 53 26. Broad guild: Open – Wet............................................................................................... 53 Broad guild: Scattered scrub – Wet .................................................................................... 57 36. Broad guild: Carr – Wet................................................................................................. 57 39. Broad guild: Open to closed-canopy – Wet .................................................................. 60 41. Broad guild: Open – Seasonally wet ............................................................................. 60 47. Broad guild: Open – Wet to damp – detritus ............................................................... 63 48. Broad guild: Open woodland – Seasonally wet ............................................................ 63 49. Broad guild: Closed-canopy woodland – Damp ............................................................ 63 50. Broad guild: Open – Shaded ......................................................................................... 63 2 51. Broad guild: Open – Mesic ............................................................................................ 66 64. Broad guild: Scattered scrub – Mesic ........................................................................... 69 65. Broad guild: Open and Scrub – Mesic ........................................................................... 69 66. Broad guild: Trees in open conditions – Mesic ............................................................. 69 74. Broad guild: Closed-canopy woodland – Mesic ............................................................ 71 79. Broad guild: Tree/Shrub cover – Mesic ........................................................................ 72 84. Broad guild: Open to closed-canopy – Mesic ............................................................... 73 Broad guild: Open – Xeric ................................................................................................... 75 88. Broad guild: Open – Wet to dry .................................................................................... 77 90. Broad guild: Tree/Shrub cover – Wet or dry ................................................................ 77 91. Broad guild: Closed-canopy woodland – Wet to dry – Detritus/fungi ......................... 77 92. Broad guild: Open to closed-canopy – Carrion ............................................................. 77 93. Broad guild: Open to closed-canopy – Detritus/fungi .................................................. 78 94. Broad guild: Subterranean ............................................................................................ 78 96. Broad guild: Saltmarsh .................................................................................................. 78 99.