Asby Complex

General site character

• Inland water bodies (Standing water, Running water) (0.3%)
  
• Bogs, Marshes, Water fringed vegetation, Fens (3%)
  
• Heath, Scrub, Maquis and Garrigue, Phygrana (42.5%)
  
• Dry grassland, Steppes (41%)
  
• Humid grassland, Mesophile grassland (0.5%)
  
• Broad-leaved deciduous woodland (1%)
  
• Inland rocks, Screes, Sands, Permanent Snow and ice (11%)
  
• Other land (including Towns, Villages, Roads, Waste places, Mines, Industrial sites) (0.7%)
  

Annex I habitats that are a primary reason for selection of this site

• 6210 Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia) (* important orchid sites)

  Asby contains extensive examples of CG9 Sesleria albicans – Galium sterneri grassland in south Cumbria on Carboniferous Limestone hills at altitudes between 230 and 470 m. The grassland occurs in a mosaic with a wide range of other habitats, including 8240 limestone pavements, 7230 alkaline fens, 6410 Molinia meadows and 4030 European dry heaths. A number of rare species are associated with the sub-montane semi-natural dry grassland, including bird’s-foot sedge Carex ornithopoda and dwarf milkwort Polygala amarella.

• 6410 Molinia meadows on calcareous, peaty or clayey-silt-laden soils (Molinion caeruleae)

  Asby is one of three sites in northern England selected for Molinia meadows, and contains examples of M26 Molinia caerulea – Crepis paludosa mire. The community occurs in extensive pastures in association with 7230 alkaline fen and 6210 semi-natural dry grassland communities, as well as locally in hydroseral transitions on lake margins.

• 7220 Petrifying springs with tufa formation (Cratoneurion)  * Priority feature

  Asby is one of three sites selected on Carboniferous limestone in northern England. Sunbiggin Tarn and Moors is considered to be the most important site in Britain for petrifying springs with tufa formation, owing to the extent of the habitat type and the degree of conservation of spring-head structures. Nearby, Crosby Gill has areas of tufa with transitions to 7230 Alkaline fens and holds good populations of alpine bartsia Bartsia alpina. Large tufa mounds formed around spring-heads are frequent. There are transitions to a range of 7230 Alkaline fens, calcareous grasslands and acid heath.

• 7230 Alkaline fens

  Asby is one of two upland sites in northern England where there are extensive flushes of M10 Carex dioica – Pinguicula vulgaris mire amidst moorland and grassland. An important example in the fen SAC series of hydroseral fen community occurs on the lake margins in the vicinity of Sunbiggin Tarn. There are also lake-side transitions to reedswamp vegetation. Away from the lake the site has an exceptionally rich flora and contains a number of rare and local northern plant species, such as bird’s-eye primrose Primula farinosa.

• 8240 Limestone pavements  * Priority feature

  Asby is one of four sites representing Limestone pavements in the north of England. It has been selected because of its size and its well-developed flora of species typical of more montane pavements and sheep-grazed pastures. Most of the pavements contain dog’s mercury Mercurialis perennis and wall lettuce Mycelis muralis, but in the main the herb flora is restricted, perhaps reflecting exposure to grazing sheep over many decades. The grikes provide a niche for a varied assemblage of ferns. Green spleenwort Asplenium viride, wall-rue Asplenium ruta-muraria, maidenhair spleenwort Asplenium trichomanes, brittle bladder-fern Cystopteris fragilis, male-fern Dryopteris filix-mas, hard shield-fern Polystichum aculeatum and hart’s-tongue Phyllitis scolopendrium occur in most pavements, with limestone fern Gymnocarpium robertianum and rigid buckler-fern Dryopteris submontana in some pavements. Where grazing is less intensive, the flora is more diverse and trees and shrubs grow beyond the confines of the grikes.

Annex I habitats present as a qualifying feature, but not a primary reason for selection of this site

• 3140 Hard oligo-mesotrophic waters with benthic vegetation of Chara spp.
• 4030 European dry heaths
• 7210 Calcareous fens with Cladium mariscus and species of the Caricion davallianae  * Priority feature

Annex II species that are a primary reason for selection of this site

• 1013 Geyer's whorl snail Vertigo geyeri

  Sunbiggin Tarn represents Geyer’s whorl snail Vertigo geyeri in north-west England. It supports a large population of this species in upland calcareous flushes with a rich assemblage of arctic-alpine plants.

• 1393 Slender green feather-moss Drepanocladus (Hamatocaulis) vernicosus

  Sunbiggin Tarn is an upland locality in north-west England supporting slender green feather-moss Drepanocladus vernicosus. The site contains a large population of this species in extensive upland flush systems and wet calcareous sedge fen on Carboniferous limestone. D. vernicosus grows here with black bog-rush Schoenus nigricans and the liverwort Leiocolea bantriensis.

Annex II species present as a qualifying feature, but not a primary reason for site selection

• Not Applicable