Acid Grassland (definition)

Durham Lowland Priority Habitats
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Lowland Acid Grassland Habitat Definition

 

Identification & Mapping

The definition of lowland for the Durham BAP is all land outside the North Pennines Natural Area.

Semi-natural grassland generally dominated by fine-leaved grasses on nutrient-poor, free-draining soils in the lowlands. Mosses and/or lichens are sometimes frequent. Managed primarily by grazing. Some sites may be species-poor (dominated, for example, by wavy hair-grass). However lowland acid grassland is a scarce resource and any site is likely to be considered of high value.

Typical grasses include:

  • common bent,
  • early hair-grass,
  • heath-grass,
  • sheep’s fescue,
  • sweet vernal-grass,
  • wavy hair-grass.
  1. If at least one of the following wild flower indicator species are frequent and another three at least occasional in the sward then the grassland meets the definition for this habitat.
  2. If three indicator species are occasional, or four are present at lower frequency (but not limited to field corners or edges) then the habitat meets this definition but must be recorded as being in poor condition.
    • Autumn Hawkbit
    • Betony
    • Bitter-vetch
    • Common Catsear
    • Devil’’s-bit scabious
    • Harebell
    • Hawkweeds
    • Heath bedstraw
    • Heath milkwort
    • Heath Speedwell
    • Heath spotted orchid
    • Lousewort
    • Mouse-eared Hawkweed
    • Sheep’s sorrel
    • Tormentil
    • Wood sage
    • Cup lichens and Dog lichens (Cladonia & Peltigera sp.)

Where lowland acid grassland occurs as part of a lowland heath mosaic it should additionally be recorded as lowland heath, unless the cover of heather is insufficient for it to meet this definition.

Condition Assessment

  1. Cover of undesirable species (creeping thistle, spear thistle, curled dock, broad-leaved dock, common ragwort, common nettle, rosebay willowherb, marsh thistle, musk thistle, greater plantain) less than 5%.
  2. Cover of bare ground (including localised areas e.g. rabbit warrens) less than 10%.
  3. Cover of scrub and bramble less than 5%.
  4. Cover of coarse grass species, such as yorkshire-fog and cock’s-foot, must be less than 20%.

Adapted from Defra’s G05 lowland dry acid grassland definition.*

*DEFRA (2005) Higher Level Stewardship: Farm Environment Plan – Guidance handbook. www.defra.gov.uk

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