Habitat account - Rocky habitats and caves


8210 Calcareous rocky slopes with chasmophytic vegetation 

Background to selection

Distribution of SACs/SCIs/cSACs with habitat 8210 Calcareous rocky slopes with chasmophytic vegetation.  Click image for enlarged map.
Distribution of SACs/SCIs/cSACs with habitat 8210 Calcareous rocky slopes with chasmophytic vegetation. Click image for enlarged map.

Description and ecological characteristics

 

Chasmophytic vegetation consists of plant communities that colonise the cracks and fissures of rock faces. The type of plant community that develops is largely determined by the base-status of the rock face. Calcareous sub-types develop on lime-rich rocks such as limestone and calcareous schists, whereas siliceous communities develop on acid rocks. The presence of calcareous bands within otherwise mainly siliceous rocks often brings the two types together on the same rock outcrop. As a result, Calcareous rocky slopes with chasmophytic vegetation may occur in close association with Annex I type 8220 Siliceous rocky slopes with chasmophytic vegetation, and some sites are listed for both types. Calcareous rocky slopes may also be closely associated with 8110 Siliceous scree of the montane to snow levels (Androsacetalia alpinae and Galeopsietalia ladani) or 8240 Limestone pavements. Lowland examples are included in the Annex I definition only where they include cliffs supporting distinctive crevice communities; coastal examples are referable to Annex I type 1230 Vegetated sea cliffs of the Atlantic and Baltic coasts.

 

Both forms of chasmophytic vegetation in the UK correspond to the rock fissure communities described from continental Europe (Asplenietea trichomanis). Some forms of the calcareous type correspond to NVC types OV39 Asplenium trichomanes – Asplenium ruta-muraria community and OV40 Asplenium viride – Cystopteris fragilis community, but other forms are not described by the NVC. The vegetation is characterised by bryophytes such as Tortella tortuosa, Anoectangium aestivum and Ctenidium molluscum. Associated vascular plants include brittle bladder-fern Cystopteris fragilis, green spleenwort Asplenium viride and glaucous meadow-grass Poa glauca.

 

Floristic variation within the habitat type is influenced by geographical location, altitude and rock type. High-altitude examples on mica schist in the Scottish Highlands have a particularly rich montane flora, including alpine woodsia Woodsia alpina, tufted saxifrage Saxifraga cespitosa and many rare bryophytes and lichens. In contrast, base-rich crevice vegetation on limestone in northern England includes some species with a predominantly southern distribution, such as bird’s-foot sedge Carex ornithopoda.

European status and distribution

 

Calcareous rocky slopes with chasmophytic vegetation appear to be widely but locally distributed in the EU.

UK status and distribution Click to view UK distribution of this habitat

 

This habitat type is widespread in upland areas of the UK but is localised in its occurrence. Depending on the nature of the rock face, individual stands are usually fragmentary. Although both calcareous and siliceous types are widely distributed in the uplands of the UK, siliceous rocks predominate and calcareous chasmophytic vegetation is of more limited overall extent.

Site selection rationale

 

The selected sites encompass the full range of geological and altitudinal variation of the habitat type, its geographical range, and its floristic diversity. Large upland sites which, in general, contain more varied and extensive examples of this habitat type, comprise the majority of the selected sites. Sites that host important populations of arctic-alpine species have been particularly favoured in site selection.


Site accounts

Ballochbuie North Eastern Scotland
Situated on the north slopes of the Dee valley below the foothills of the Lochnagar massif, the geology at Ballochbuie is mostly dominated by granites of various degrees of acidity. In the west of the site it is more complex with various outcrops of metamorphic rocks, the most prominent of which is the vertical outcrop of calcareous rock known as the Lion’s Face. On the hillside above the face, further outcrops of calcareous rock give rise to small areas of CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland and open birch woodland, contrasting with the Scots pine Pinus sylvestris woodland over most of the rest of the site. Alpine cinquefoil Potentilla crantzii is present on these outcrops. Closer to the cliffs of the Lion’s Face, small areas of scrub and more extensive plantations provide additional shade. Here, rock faces, crevices and boulders support communities of ferns, and, in particular, lichens and bryophytes. Ferns include green spleenwort Asplenium viride and Wilson’s filmy-fern Hymenophyllum wilsonii. A large number of rare lichens are present including a species normally associated with elm, Gyalecta ulmi, and Chaenotheca gracilenta (both Endangered). The moss Pseudoleskeella rupestris (Nationally rare) also occurs.
Beinn a' Ghlo Eastern Scotland
Beinn a’Ghlo represents Calcareous rocky slopes with chasmophytic vegetation in the eastern Highlands, with additional rare species. There are extensive outcrops of limestone in Glen Tilt, up to about 700 m altitude. The flora includes a large colony of the rare yellow oxytropis Oxytropis campestris, while other montane species include mountain avens Dryas octopetala, rock speedwell Veronica fruticans, rock sedge Carex rupestris, hoary whitlowgrass Draba incana, holly fern Polystichum lonchitis and green spleenwort Asplenium viride.
Beinn Dearg Highlands and Islands
Beinn Dearg holds the best example of Calcareous rocky slopes with chasmophytic vegetation in the north-west Highlands. Many of the high altitude cliffs are strongly calcareous and have a rich arctic-alpine flora including mountain avens Dryas octopetala, net-leaved willow Salix reticulata, alpine saxifrage Saxifraga nivalis, hoary whitlowgrass Draba norvegica, alpine cinquefoil Potentilla crantzii, glaucous meadow-grass Poa glauca and black alpine-sedge Carex atrata.
Beinn Iadain and Beinn na h' Uamha Highlands and Islands
Beinn Iadain and Beinn na h’Uamha is representative of Calcareous rocky slopes with chasmophytic vegetation at moderately high altitudes in the oceanic north-west Scottish Highlands. The communities develop on extensive crags of calcareous basalt, which provides a refugium for a rich calcicolous flora. Characteristic chasmophytic vascular plants include alpine saxifrage Saxifraga nivalis, northern rock-cress Arabis petraea, glaucous meadow-grass Poa glauca and holly-fern Polystichum lonchitis. There is a rich associated flora of calcicolous bryophytes, such as Orthothecium rufescens and Rhytidium rugosum.
Ben Alder and Aonach Beag Highlands and Islands
Ben Alder and Aonach Beag has an outstanding flora of rare arctic-alpine calcicoles mostly associated with a high-altitude band of limestone at 900-1000 m. The flora includes tufted saxifrage Saxifraga cespitosa, alpine saxifrage S. nivalis, hoary whitlowgrass Draba norvegica, mountain avens Dryas octopetala, black alpine-sedge Carex atrata and alpine meadow-grass Poa alpina. Various rare montane calcicolous mosses and lichens also occur on the rock faces.
Ben Heasgarnich Eastern Scotland, Highlands and Islands
Ben Heasgarnich in the central Breadalbane Hills in the southern Highlands is representative of high-altitude Calcareous rocky slopes with chasmophytic vegetation. There are extensive calcareous schist outcrops with a wide range of characteristic chasmophytic plant species. Of particular interest is the very rare high-altitude crevice flora, which includes species such as mountain bladder-fern Cystopteris montana, oblong woodsia Woodsia ilvensis and rock whitlowgrass Draba norvegica. This is one of the most important sites in the UK for arctic-alpine flora because of the number of rare species present.
Ben Lawers Eastern Scotland
Ben Lawers is representative of high-altitude Calcareous rocky slopes with chasmophytic vegetation in the central Scottish Highlands. The rock faces are formed on calcareous schists and limestones outcropping extensively at very high altitude. The site supports extensive areas of chasmophytic vegetation with some of the most diverse examples of these communities in the UK. They contain a large number of nationally rare species, such as drooping saxifrage Saxifraga cernua, rock whitlowgrass Draba norvegica, alpine fleabane Erigeron borealis, alpine forget-me-not Myosotis alpestris, rock sedge Carex rupestris, alpine gentian Gentiana nivalis, mountain bladder-fern Cystopteris montana and alpine woodsia Woodsia alpina. The montane calcicole bryophyte and lichen flora of this site is outstanding.
Ben Lui Eastern Scotland, Highlands and Islands
Ben Lui represents Calcareous rocky slopes with chasmophytic vegetation in an oceanic climate at the western end of the Breadalbane range. There is a wide band of calcareous schist forming crags at altitudes of 460-760 m on northerly slopes. The flora includes a number of rare montane calcicoles including mountain avens Dryas octopetala, hoary whitlowgrass Draba norvegica, mountain bladder-fern Cystopteris montana, alpine woodsia Woodsia alpina and net-leaved willow Salix reticulata.
Ben Nevis Highlands and Islands
Within the Ben Nevis site limestone occurs up to high altitude, notably on Aonach Beag, and this is one of the richest areas outside of the Breadalbane range and Caenlochan for arctic-alpines of calcareous rocks. Calcareous rocky slopes with chasmophytic vegetation are well-represented and Ben Nevis is notable for populations of a number of very rare species which are associated with calcareous outcrops of rock faces in high gullies. These include tufted saxifrage Saxifraga cespitosa, drooping saxifrage S. cernua and Highland saxifrage S. rivularis. Other national rarities of rock outcrops include glaucous meadow-grass Poa glauca, alpine meadow-grass Poa alpina, arctic mouse-ear Cerastium arcticum and alpine saxifrage Saxifraga nivalis. Other arctic-alpines represented include rose-root Sedum rosea, alpine scurvygrass Cochlearia pyrenaica ssp. alpina, mountain sorrel Oxyria digyna, holly fern Polystichum lonchitis, mossy saxifrage Saxifraga hypnoides and purple saxifrage S. oppositifolia.
Binevenagh Northern Ireland
Binevenagh is the only site representing Calcareous rocky slopes with chasmophytic vegetation in Northern Ireland. The site comprises steeply-rising basalt cliffs with a range of chasmophytic species. Of particular interest is the remnant arctic-alpine flora, in addition to plants that are more usually associated with coastal locations. Species include mountain avens Dryas octopetala, moss campion Silene acaulis, purple saxifrage Saxifraga oppositifolia, thrift Armeria maritima and sea campion Silene uniflora. Notable bryophytes such as Tortula princeps also occur.
Brecon Beacons/ Bannau Brycheiniog East Wales
The Old Red Sandstone cliffs of the Brecon Beacons support the most southerly representation of Calcareous rocky slopes with chasmophytic vegetation in the UK. The relatively high base-status of the actively eroding rocks has resulted in a chasmophytic flora which is comparatively rich for this southerly site. Species include purple saxifrage Saxifraga oppositifolia at its most southerly British location, green spleenwort Asplenium viride, brittle bladder-fern Cystopteris fragilis and several rare Hieracium spp. Nationally scarce bryophyte species include Plagiopus oederianus and Scapania aequiloba.
Cadair Idris West Wales and The Valleys
Cadair Idris is one of three Welsh sites representing Calcareous rocky slopes with chasmophytic vegetation. It is the highest mountain in the south of the Snowdonia National Park and has a number of cliffs and rock outcrops with base-rich exposures, with the moist, north-facing cliffs supporting a number of notable bryophytes. Many of the higher plants are clustered below the tall-herb ledge vegetation where water streams down from above and include species such as green spleenwort Asplenium viride and purple saxifrage Saxifraga oppositifolia.
Caenlochan Eastern Scotland, North Eastern Scotland
Caenlochan represents high-altitude Calcareous rocky slopes with chasmophytic vegetation in the eastern Highlands, on extensive outcrops of calcareous schists. The site has one of the most extensive and diverse high-altitude crevice habitats in the UK, with an abundance of characteristic high montane plant species. These include a number of rare species, such as mountain bladder-fern Cystopteris montana, alpine woodsia Woodsia alpina, rock sedge Carex rupestris, glaucous meadow-grass Poa glauca and hoary whitlowgrass Draba incana. The montane calcicole bryophyte flora is also outstanding and includes a number of species not present on other selected sites.
Eryri/ Snowdonia West Wales and The Valleys
Snowdonia is representative of Calcareous rocky slopes with chasmophytic vegetation at one of its most southerly outposts in the UK, and contains the most extensive and diverse examples of these communities in Wales. Crevices in base-rich igneous rocks support a characteristic assemblage of plants, with a large number of arctic-alpine species. These include a number of nationally rare species, such as alpine saxifrage Saxifraga nivalis, tufted saxifrage S. cespitosa, alpine meadow-grass Poa alpina and alpine woodsia Woodsia alpina. A species of particular interest is the Snowdon lily Lloydia serotina, which in the UK occurs only in Snowdonia, in rock cracks and crevices on calcareous and more siliceous substrates, and is here at its northern limit in western Europe.
Glen Coe Highlands and Islands
Glen Coe represents Calcareous rocky slopes with chasmophytic vegetation through its base-rich outcrops from moderate to high altitude including limestone and calcareous schists on Meall Mór and lime-rich bands in igneous rocks on Bidean nam Bian. The flora includes the rare saxifrages drooping saxifrage Saxifraga cernua and alpine saxifrage S. nivalis and other rare montane species include mountain bladder-fern Cystopteris montana, green spleenwort Asplenium viride, holly fern Polystichum lonchitis, glaucous meadow-grass Poa glauca and hoary whitlowgrass Draba norvegica. Other calcicoles occurring on rock include lesser meadow-rue Thalictrum minus.
Inchnadamph Highlands and Islands
Inchnadamph is representative of Calcareous rocky slopes with chasmophytic vegetation in the north of Scotland. This habitat type occurs extensively on northerly crags of Durness dolomitic limestone at low altitude. It has a diverse flora, rich in characteristic northern species including abundant holly-fern Polystichum lonchitis, dark-red helleborine Epipactis atrorubens, bearded couch Elymus caninus and rock sedge Carex rupestris. There are rare sub-montane calcicole bryophytes associated with the crevice flora, such as Tortula princeps, Amblystegium compactum and Seligeria trifaria.
Ingleborough Complex North Yorkshire
Ingleborough is one of three sites representing the Calcareous rocky slopes with chasmophytic vegetation found in northern England. Crevice communities occur on extensive limestone scars and are characteristic of the area. The flora has a mix of northern and southern species, including purple saxifrage Saxifraga oppositifolia, yellow saxifrage S. aizoides, alpine meadow-grass Poa alpina, hoary whitlowgrass Draba incana, lesser meadow-rue Thalictrum minus, wall lettuce Mycelis muralis and baneberry Actaea spicata.
Moor House - Upper Teesdale Cumbria, Tees Valley and Durham
This is one of three sites representing Calcareous rocky slopes with chasmophytic vegetation in the north of England. Crevice communities occur on extensive limestone scars, especially along the Pennine escarpment and around the summits of hills. Cliff crevice vegetation occurs extensively and to an altitude of 760 m. The most extensive community present is characterised by green spleenwort Asplenium viride and brittle bladder-fern Cystopteris fragilis. Less common species found in this community include hoary whitlowgrass Draba incana, alpine cinquefoil Potentilla crantzii and holly-fern Polystichum lonchitis. The site is also of interest for its combination of southern and northern flora. Rarer southern species include bird’s-foot sedge Carex ornithopoda and horseshoe vetch Hippocrepis comosa. The whitebeam Sorbus rupicola, which is widely distributed but found at only a few sites, is also present.
Strath Highlands and Islands
Strath represents low-altitude Calcareous rocky slopes with chasmophytic vegetation in northern Scotland. This is one of the few sites in this area with a markedly calcareous chasmophytic flora, associated with outcrops of Dalradian Durness limestone. The crevice flora is moderately well-developed but is less extensive and diverse than those at higher altitudes. There are only a few rare arctic-alpine species, including rock sedge Carex rupestris and alpine cinquefoil Potentilla crantzii. However, the communities contain an unusual assemblage of species characteristic of both a northern and a more southerly distribution. Northern species include dark-red helleborine Epipactis atrorubens, green spleenwort Asplenium viride and holly-fern Polystichum lonchitis, while southern species include hart’s-tongue Phyllitis scolopendrium.
Trotternish Ridge Highlands and Islands
Trotternish is representative of Calcareous rocky slopes with chasmophytic vegetation in north-west Scotland. There are extensive basalt cliffs, on which calcareous outcrops occur locally at moderately high altitude, higher than on the comparable site, Strath. These outcrops support characteristic crevice-dwelling plants. Of particular interest are the ferns green spleenwort Asplenium viride, brittle bladder-fern Cystopteris fragilis and holly-fern Polystichum lonchitis, and various calcicolous mosses. There is a moderately rich flora of arctic-alpine calcicoles, including glaucous meadow-grass Poa glauca, alpine meadow-grass Poa alpina, hoary whitlowgrass Draba incana and alpine saxifrage Saxifraga nivalis. The oceanic bryophyte flora associated with this habitat type is thought to be among the richest in the SAC series and includes the liverworts Colura calyptrifolia, Harpalejeunea ovata, Herbertus stramineus and Plagiochila spinulosa.

SACs/SCIs/cSACs where this Annex I habitat is a qualifying feature, but not a primary reason for site selection

Berwyn a Mynyddoedd de Clwyd/ Berwyn and South Clwyd Mountains East Wales, West Wales and The Valleys
Cairngorms Highlands and Islands, North Eastern Scotland
Creag Meagaidh Highlands and Islands
Foinaven Highlands and Islands
Hoy Highlands and Islands
Lake District High Fells Cumbria
Loch Maree Complex Highlands and Islands
Meall na Samhna Eastern Scotland
Moffat Hills South Western Scotland
North Pennine Moors Cumbria, North Yorkshire, Northumberland and Tyne and Wear, Tees Valley and Durham
Peak District Dales Derbyshire and Nottinghamshire, Shropshire and Staffordshire
Rassal Highlands and Islands
Rum Highlands and Islands
Strathglass Complex Highlands and Islands
Usk Bat Sites/ Safleoedd Ystlumod Wysg East Wales, West Wales and The Valleys
 

Many designated sites are on private land: the listing of a site in these pages does not imply any right of public access.