Lowland Fen

Durham Lowland Priority Habitats
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Lowland Fen Action Plan

Priority Habitat and Species: Lowland Fen habitatsPhragmites australis ReedbedOtter, Water Vole, Reed Bunting

Priorities

  1. Identify and maintain the current extent and distribution of lowland fen and achieve favourable ecological condition.
  2. Safeguard lowland fen sites and ensure appropriate management for BAP species.
  3. Increase the resource of lowland fen through habitat creation on suitable sites and restoration of degraded fen sites.

Lowland Fen Targets
Vision Statement: To maintain the extent and quality of fen habitats through the protection and restoration of their buffer zones and associated hydrology.

Target Type Unit Value
1. To maintain the current extent of lowland fen habitats in the Durham BAP area. maintain ha tbc
2. To restore lowland fen habitats on former known sites in the Durham BAP area. restore ha 30

Phragmites australis Reedbed Targets
Vision StatementTo increase the number, size and connectivity of Phragmites australis reedbed.

Target Type Unit Value
1. To maintain the extent of Phragmites australis reedbed in the Durham BAP area. maintain ha tbc
2. To expand the extent of Phragmites australis reedbed in the Durham BAP area by 30ha. expand ha 30
3. To increase the number of Phragmites australis reedbed sites of 2ha or more in the Durham BAP area by 1 site achieve condition number of sites 1

Otter Targets
Vision Statement: To increase the population to the carrying capacity in all rivers systems.

Target Type Unit Value
1. To expand the current range of otter to 22 five kilometre squares. expand 5km2 22

Water Vole Targets
Vision Statement: To achieve an expansion of both population and range.

Target Type Unit Value
1. To maintain the current population and range of water voles within the Durham BAP area. maintain occupied km squares  67
2. To expand the current range of water vole in the Durham BAP area by 20 sites every 5 years. expand sites 20

Reed Bunting Targets

Target Type Unit Value
1. To maintain the range of reed bunting in the Durham BAP area. maintain BBS squares 4 squares 12.9%

Fen habitats are wetlands overlying both peat and mineral soils and fed by groundwater as well as rainwater. (True bogs in contrast are rainwater fed only, but their vegetation may be difficult to distinguish from fens). Fens with vertical water movement include basin and flood plain mires, and those with lateral water movement include valley mires, and springs and flushes.

Hydrology varies between and within fen types, from water table above ground for much or most of the year to water table near the surface for only part of the year. Swamp, Phragmites australis reedbed and Marsh are synonyms for certain types of fen community on particular substrates, with particular dominant species or with particular hydrology.

This is a difficult habitat to define, and is often present as only a small element of another habitat, including grassland, heath, wet woodland, water bodies and blanket bog. Ponds undergoing seral succession from open water to scrub also fit within this definition.

Swamps are a type of fen which have the water table distinctly above the substratum for much of the year and are often located on the margins of open water or in ditches. They are dominated by tall grasses, reeds and large sedges in single or mixed species stands. Typical species include reedmace, common reed, reed canary grass and bottle sedge. Swamps dominated by common reed are classed as Phragmites australis reedbed.

There are around 5000 hectares of reedbed in the UK, however only 50 of the 900 or so sites are greater than 20 hectares. These are mainly concentrated in the south and east of England and make up the majority of the total area. Reedbeds are one of the most important bird habitats in the country. The UK holds a large proportion of the surviving fen in Europe, although this has declined in the last century

Reedbed is an important habitat for DBAP species including Reed Bunting and Water Vole.

This plan is concerned only with lowland fen habitats. Upland fen, of which there is a great deal, is part of the mosaic with blanket bog, upland heath and grassland habitats, and is dealt with as part of the relevant plans.

Threats

  • A lack of suitable management- e.g. mowing, grazing, burning, peat cutting, scrub clearance. Without appropriate management and as a result of natural succession fen will dry out and form scrub and woodland.
  • Drainage for agricultural intensification. New drains now require Environment Impact Assessment, reducing the risk of future drainage impacting on fens.
  • Excessive water abstraction from aquifers may dry up or reduce spring line flows and generally lower water tables. Abstractions may also affect the natural balance between the differing water qualities of ground and surface water, thereby adversely affecting the habitats.
  • Agricultural run-off and afforestation within their water catchments, valley fens are particularly susceptible.
  • Nutrient enrichment (eutrophication) causes an increased growth and dominance of vigorous plant species, which may lead to a loss of biodiversity and possibly reed death.
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