Craven Limestone Complex

General site character

• Inland water bodies (Standing water, Running water) (1%)
  
• Bogs, Marshes, Water fringed vegetation, Fens (3%)
  
• Dry grassland, Steppes (85%)
  
• Broad-leaved deciduous woodland (1%)
  
• Inland rocks, Screes, Sands, Permanent Snow and ice (10%)
  

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

• 3140 Hard oligo-mesotrophic waters with benthic vegetation of Chara spp.

  Malham Tarn in northern England is considered the best example of an upland stonewort Chara-dominated lake in England. It is an example of a lake on limestone and is the highest marl lake in the UK. The water drains from surrounding Carboniferous limestone and is calcareous and low in plant nutrients, although the Tarn has a large catchment and some nutrient enrichment to the system has occurred in the past, slightly reducing the floristic richness.

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

  The Craven Limestone Complex in northern England is the second most extensive area of calcareous grassland in the UK, and represents the NVC type CG9 Sesleria albicans – Galium sterneri grassland. The site exhibits an exceptional diversity of structural types, ranging from hard-grazed open grasslands, through to tall herb-rich grasslands on ungrazed cliff ledges, such as at Malham Cove, in woodland margins and around 8240 Limestone pavements and screes. It is thus an important example of grassland-scrub transitions.

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

  Craven is one of three sites representing Molinia meadows in the northern England centre of distribution. This site contains what are believed to be the largest expanses of M26 Molinia caerulea – Crepis paludosa mire in the UK, amidst 7230 Alkaline fens and 7110 active raised bog communities of the Malham Tarn area; smaller fragments are associated with meadows, wood edges and river banks elsewhere on the site.

• 7110 Active raised bogs  * Priority feature

  Malham Tarn Moss represents Active raised bogs in central northern England, in an area overlying limestone where wetlands are more typically base-rich fens. It displays a classic raised dome with transition from raised bog (base-poor) to base-rich conditions at the bog margin where it interfaces with land influenced by water from the limestone. It has an unusual mixture of bog-moss Sphagnum-rich and hair-grass Deschampsia-dominated vegetation.

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

  Craven is one of three Carboniferous limestone sites in northern England selected for petrifying springs with tufa formation. The site contains extensive complexes of tufa-forming springs associated with a wide range of other habitats, including 7230 Alkaline fens, calcareous grasslands, 8240 Limestone pavements, cliffs and screes. Locally calcareous springs emerge within areas of acid drift supporting heath and acid grassland. The flora of these habitat mosaics is outstandingly species-rich and includes many rare northern species, such as alpine bartsia Bartsia alpina and bird’s-eye primrose Primula farinosa.

• 7230 Alkaline fens

  There are large fen systems at Great Close and Ha Mire, principally of the NVC type M10b Carex dioica – Pinguicula vulgaris mire, Briza media – Primula farinosa sub-community. They are exceptionally species-rich types with frequent bird’s-eye primrose Primula farinosa and grass-of-Parnassus Parnassia palustris alongside rarities such as broad-leaved cottongrass Eriophorum latifolium, hair sedge Carex capillaris, alpine bartsia Bartsia alpina and dwarf milkwort Polygala amarella. Where irrigation is more extensive there are transitions to M9a Carex rostrata – Calliergon cuspidatum/ giganteum mire, Campylium stellatum – Scorpidium scorpioides sub-community. This community is also developed extensively around the lagg of Tarn Moss, where there are transitions with M26b Molinia caerulea – Crepis paludosa mire, Festuca rubra sub-community and W3 Salix pentandra – Carex rostrata fen carr woodland. There are also extensive M10 Carex dioica – Pinguicula vulgaris spring-fed flush fens throughout the site, typically associated with calcareous grassland and limestone scars.

• 8240 Limestone pavements  * Priority feature

  Craven is one of four sites representing Limestone pavements in northern England. It is selected on the basis of its size and as an example of mid-altitude pavement. There is a wide range of transitions to other habitats, including 6210 semi-natural dry grasslands, 7230 Alkaline fens and 9180 Tilio-Acerion forests. Despite being accessible to grazing sheep, these pavements provide a refuge for downy currant Ribes spicatum and, occasionally, alpine cinquefoil Potentilla crantzii and baneberry Actaea spicata.

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

• 6130 Calaminarian grasslands of the Violetalia calaminariae
• 9180 Tilio-Acerion forests of slopes, screes and ravines  * Priority feature

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

• 1092 White-clawed (or Atlantic stream) crayfish Austropotamobius pallipes

  Craven in northern England supports strong populations of white-clawed crayfish Austropotamobius pallipes in the limestone streams feeding Malham Tarn, and in Malham Tarn itself. This site is well-isolated and is therefore an important refuge, unlikely to be invaded by non-native crayfish species.

• 1163 Bullhead Cottus gobio

  Craven represents bullhead Cottus gobio in calcareous, upland becks and streams in the northern part of its range in England. The clean calcareous waters with their stony bottoms support good numbers of bullhead.

• 1902 Lady's-slipper orchid Cypripedium calceolus

  Craven Limestone Complex is the single remaining native site for Lady’s-slipper orchid Cypripedium calceolus. Formerly reduced to a single plant, careful habitat management, together with hand-pollination of the few flowers that appear, and more recently re-establishment of plants from ex-situ propagation, has led to a steady increase in the size of the colony.

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

• Not Applicable