County Wildife Site Criteria for Cornwall Appendices

LOWLAND FENS PHTGeneral DescriptionFens are peatlands which receive water and nutrients from the soil, rock and ground water as well asfrom rainfall: they are minerotrophic.Fens can also be described as `poor-fens` or `rich-fens`. Poor-fens, where the water is derived frombase-poor rock such as granites occur mainly in the uplands, or are associated with lowland heaths.They are characterised by short vegetation with a high proportion of bog mosses Sphagnum spp..Rich-fens, are fed by mineral-enriched calcareous waters (pH 5 or more) and are mainly confined tothe lowlands.Fen habitats support a diversity of plant and animal communities. Some can contain up to 550 speciesof higher plants, a third of our native plant species; up to and occasionally more than half the UK`sspecies of dragonflies, several thousand other insect species, as well as being an important habitat fora range of aquatic beetles.National ContextIn intensively farmed lowland areas fens occur less frequently, are smaller in size and more isolatedthan in other parts of Britain. There are, however, exceptions to this. Britain`s largest continuousarea of base-poor fen, the Insh Marshes in the floodplain of the River Spey in Scotland, covers an areaof 300 ha, the calcareous rich fen and the swamp of Broadland covers an area of 3000 ha.Area of PHT in Cornwall (ha): estimated (est) 3110Number of polygons: est 2200The habitat is: Fairly commonDistribution by Administrative DistrictDistrict P K CK R CN NC ΣNumber 249 371 265 393 nk nk est 2200Area (ha) 350 420 210 580 nk nk est 3110Distribution by Natural AreaDistrict Pe Lz CKG BM Cu ΣNumber 187 151 1445 est 136 281 est 2200Area (ha) 270 200 1560 est 830 250 est 3110nk=not knownFor this habitat the threshold is 2.5 haAppendix 4 - Information Relating to Priority Habitat TypesCounty Wildlife Sites Criteria