Bolshayne Fen

Bolshayne Fen (gbmapping|SY222938) is a wetland in southeast Devon, England. It has an area of 1.62 hectares.

The site was designated as a Site of Special Scientific Interest on 25 September 1992.

ite Description

This site contains an unusually large and intact valley fen, supporting rich marsh vegetation of a type known only at two other sites in Devon and which is now nationally scarce. The fen occupies a single field at an altitude of 40 m, through which runs a small stream called Nanny's Water, which is a tributary of the River Coly. Its soils consist of deep waterlogged peaty loam above Triassic mudstones, with Cretaceous Greensand on the valley sides above. During winter it periodically floods.

Vegetation

The vegetation is comprised mainly of a mosaic of Yellow Flag Iris "Iris pseudacorus", Branched Bur-reed "Sparganium erectum" and rushes "Juncus" spp., while Greater Tussock-sedge "Carex paniculata" is locally dominant. Other conspicuous plants include Meadowsweet "Filipendula ulmaria", Marsh-marigold "Caltha palustris", Ragged Robin "Lychnis flos-cuculi", Watermint "Mentha aquatica" and Southern marsh-orchid "Dactylorhiza praetermissa". Also present are four species which are local in Devon: Wood club-rush "Scirpus sylvaticus", Marsh Valerian "Valeriana dioica", Fen Bedstraw "Galium uliginosum" and Common Spike-rush "Eleocharis palustris". The stream is bordered for most of its length by Alder "Alnus glutinosa", with a ground flora dominated by Ramsons "Allium ursinum".

Other biodiversity interest

Brown trout "Salmo trutta fario" and Eel "Anguilla anguilla" are known to occur in Nanny's Water. The site supports a varied reptile fauna, including Grass Snake "Natrix natrix" and Adder "Vipera berus". It also supports a number of bird species including Water Rail, which rarely breeds in Devon but has been recorded during the summer at this site. During the winter Snipe and Woodcock commonly feed within the fen, and Grey Heron and Barn Owl occur.