SBI Guidelines: Fen and Swamp
Fen is defined as a wetland type often following swamp in the hydroseral succession. Fens have a summer water table at or below the sediment surface but being flooded in winter. Can be divided into poor and rich fens, based both on chemical composition of the fen waters and the species diversity of the vegetation” (Sites of Importance for Nature Conservation in North Yorkshire, 2002).
Swamp is defined as "a freshwater wetland habitat characteristic of lake margins in both organic and inorganic materials contribute to sediment surface and the vegetation is usually dominated by herbaceous monocotyledons. Species diversity is often low with plant communities often dominated by 1 or 2 species" (Sites of Importance for Nature Conservation in North Yorkshire, 2002).
Sites of Biological Importance
- Any fen and/or swamp site over 0.5ha in size except where they are dominated by Urtica dioica (Common Nettle), Impatiens glandulifera (Himalayan/Indian Balsam) and/or Typha latifolia (Bulrush); to the exclusion of other species.
- Any fen and/or swamp site between 0.25ha and 0.5ha, in excess of 20m wide and adjacent to another SBI or BAS habitat, except where they are dominated by Urtica dioica, Impatiens glandulifera and/or Typha latifolia
- Other species of note include Micromys minutes (Harvest Mouse) and Neomys fodiens (Water Shrew), all sites with known populations should be considered for inclusion.
Biodiversity Alert Site
- Any Swamp and/or fen site between 0.25ha and 0.5ha, and in excess of 20m wide, except where they are dominated by Urtica dioica, Impatiens glandulifera and/or Typha latifolia.
- Any swamp and/or fen site adjacent to another BAS habitat except where they are dominated by Urtica dioica and/or Impatiens glandulifera and/or Typha latifolia.
- North Yorkshire SINC Panel (2002) Sites of Importance for Nature Conservation in North Yorkshire (Outside the Yorkshire Dales and North York Moors National Parks boundaries) Guidelines for Site Selection North Yorkshire County Council, Northallerton North Yorkshire available from http://www.neyedc.org.uk/docs20080401/North%20Yorkshire%20SINC%20Panel/SINC%20Guidelines%20V2.1%20-%20August%2009.pdf
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