6150 Siliceous alpine and boreal grasslands

European status and distribution

Siliceous alpine and boreal grasslands have a restricted distribution in the EU. The UK and Ireland support the only examples of this vegetation within the Atlantic Biogeographical Region. Outside the EU, the sub-types dominated by woolly fringe-moss Racomitrium lanuginosum are restricted to oceanic, northern lands, such as the Faeroe Islands and Iceland.

UK status and distribution

In the UK extensive areas of Siliceous alpine and boreal grasslands occur chiefly in Scotland, but there are important southern outliers in northern England, north Wales and Northern Ireland, where the southern limit of the habitat in the EU is reached. In many of the southern outliers the extent of the habitat is smaller than on sites in Scotland and the degree of modification is often greater.

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Site accounts

• Beinn Dearg Highlands and Islands
  Beinn Dearg has the third-largest area of this habitat type in the UK and the second-largest in the north-west Highlands. There is extensive development of U7 Nardus stricta – Carex bigelowii grass-heath and of both the species-poor and species-rich forms of U10 Carex bigelowii – Racomitrium lanuginosum moss-heath. The species-rich form is well-developed and reaches its second-largest extent within the SAC series on this site. Species-rich Carex – Racomitrium moss-heath is associated with base-rich schist on extensive solifluction terracing. This is enriched with arctic-alpine and northern vascular plants, including moss campion Silene acaulis, cyphel Minuartia sedoides, three-leaved rush Juncus trifidus, spiked wood-rush Luzula spicata, sibbaldia Sibbaldia procumbens, dwarf cudweed Gnaphalium supinum and mountain everlasting Antennaria dioica, accompanied by the rare montane calcicole mosses Hypnum hamulosum and Aulacomnium turgidum. Beinn Dearg is one of only two mountains in the north-west Highlands on which the rare Norwegian mugwort Artemisia norvegica is known to occur. Moss- and dwarf-herb-dominated snow-bed communities (U11 Polytrichum sexangulare – Kiaeria starkei snow-bed, U12 Salix herbacea – Racomitrium heterostichum snow-bed and U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb community) are well-represented but are not extensive.
• Ben Alder and Aonach Beag Highlands and Islands
  These ranges of hills have the largest area of ground above 1000 m in Britain outside of the Cairngorms and the extent of Siliceous alpine and boreal grassland is correspondingly high. The range of communities is representative of the higher hills of the central Highlands, with all the NVC types associated with the habitat represented. The most extensive communities are U7 Nardus stricta – Carex bigelowii grass-heath and U10 Carex bigelowii – Racomitrium lanuginosum moss-heath, the latter with an unusual occurrence of a species-rich sub-type following a band of high-altitude limestone. This site represents one of only six sites outside of the Cairngorms and Ben Nevis with extensive late-lie mossy snow-beds holding U11 Polytrichum sexangulare – Kiaeria starkei and U12 Salix herbacea – Racomitrium heterostichum snow-bed communities. Various rare plants occur in the snow-beds, including starwort mouse-ear Cerastium cerastoides and the bryophytes Dicranum glaciale, Marsupella condensata and Nardia breidleri. U8 Carex bigelowii – Polytrichum alpinum sedge-heath attains its largest extent outside of the eastern Highlands.
• Ben Heasgarnich Eastern Scotland, Highlands and Islands
  Ben Heasgarnich is the best representative for Siliceous alpine and boreal grassland of the Dalradian schist hills of the Breadalbane range. All the NVC types belonging to the habitat are represented, with U7 Nardus stricta – Carex bigelowii grass-heath and U10 Carex bigelowii – Racomitrium lanuginosum moss-heath being the predominant communities on the high ground of the summits and summit ridges. The underlying schists are base-rich and Ben Heasgarnich is primarily of importance for supporting the largest extent in the SAC series of species-rich Carex – Racomitrium moss-heath. This has an abundance of arctic-alpine species, such as moss campion Silene acaulis, mossy cyphel Minuartia sedoides, alpine bistort Persicaria vivipara and alpine meadow-rue Thalictrum alpinum. There are also some small but notably species-rich examples of late-lie snow-beds belonging to U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb community. Moss-dominated snow-beds are well-represented but are of small extent.
• Ben Nevis Highlands and Islands
  With the exception of Beinn Dearg and the Loch Maree Complex in the north, Ben Nevis has the most extensive development of Siliceous alpine and boreal grassland in the western Highlands. On the summit plateau of Aonach Mór U10 Carex bigelowii – Racomitrium lanuginosum moss-heath occurs as the highest extensive stand in the UK. The normal dominant Racomitrium lanuginosum is in part replaced on Aonach Mór by R. canescens (sensu lato), which provides affinities with the vegetation of Iceland and Jan Mayen. The R. canescens is associated with open, wind-blown sandy areas where there is active erosion and deposition of sand caused by the exceptionally high altitude and exposure. Other wind-eroded areas among Carex – Racomitrium moss-heath may be colonised by three-leaved rush Juncus trifidus, and the national rarity curved wood-rush Luzula arcuata. Frequent arctic-alpines in the Carex – Racomitrium moss-heath include least willow Salix herbacea, spiked wood-rush Luzula spicata, J. trifidus and moss campion Silene acaulis. U7 Nardus stricta – Carex bigelowii grass-heath is extensive and occurs mostly in corries and in hollows on ridges where snow lies late. U8 Carex bigelowii – Polytrichum alpinum sedge-heath occurs on the higher summits where snow lies late in hollows and is more abundant on this site than on any other site in the western Highlands. These communities are associated with some of the most extensive moss-dominated late-lie snow beds (U11 Polytrichum sexangulare – Kiaeria starkei and U12 Salix herbacea – Racomitrium heterostichum snow-beds) outside of the Cairngorms.
• Ben Wyvis Highlands and Islands
  Ben Wyvis is representative of the species-poor form of U10 Carex bigelowii – Racomitrium lanuginosum moss-heath of the north and west of Scotland. Although Siliceous alpine and boreal grasslands are not as extensive on Ben Wyvis as on some other hills, the site has the largest continuous single tract of this sub-type in the UK, covering almost the whole of the summit plateau. The habitat type is developed on base-poor schist. There is also a large extent of the associated Rhytidiadelphus loreus moss-rich grassland on the edges of the Carex – Racomitrium moss-heath, where snow tends to drift. The site is little-disturbed and shows a particularly luxuriant moss-cover. U7 Nardus stricta – Carex bigelowii grass-heath is also well-represented and U8 Carex bigelowii – Polytrichum alpinum sedge-heath is present locally. Late-lie moss- and dwarf-herb-dominated snow-bed communities (U11 Polytrichum sexangulare – Kiaeria starkei snow-bed, U12 Salix herbacea – Racomitrium heterostichum snow-bed and U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb community) are represented on Ben Wyvis but are small in extent.
• Caenlochan Eastern Scotland, North Eastern Scotland
  Caenlochan is representative of Siliceous alpine and boreal grasslands on high hills in the eastern Highlands. This is the most continental site in the series and is unique because it is the only site where the predominant community of the summit plateau is U8 Carex bigelowii – Polytrichum alpinum sedge-heath rather than the more widely predominant U10 Carex bigelowii – Racomitrium lanuginosum moss-heath. The extent of Carex – Polytrichum sedge-heath is the largest of any site in the UK. The more characteristically oceanic Carex – Racomitrium moss-heath is represented by some good stands but is not so extensive. U7 Nardus stricta – Carex bigelowii grass-heath is also well-represented. There is a moderately large representation of late-lie snow-beds of U11 Polytrichum sexangulare – Kiaeria starkei snow-bed and U12 Salix herbacea – Racomitrium heterostichum snow-bed, while some small examples of U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb snow-bed are also present on shelves on high ground.
• Cairngorms Highlands and Islands, North Eastern Scotland
  The Cairngorms complex (Cairngorms, eastern Cairngorms, Northern Corries and Inchrory) has the largest tracts of Siliceous alpine and boreal grasslands in the UK, developed on granite and, more locally, base-poor schist up to very high altitudes (above 1000 m). The total extent is more than twice that on any other site in the UK. The full range of sub-types on acidicsoils is well developed and they are widespread. Both U10 Carex bigelowii – Racomitrium lanuginosum moss-heath and U7 Nardus stricta – Carex bigelowii grass-heath are extensive. The U9 Juncus trifidus – Racomitrium lanuginosum rush-heath community is particularly well-developed, becoming predominant on the higher plateau, and its extent far exceeds that on any other site in the UK. The stands of U8 Carex bigelowii – Polytrichum alpinum sedge-heath are among the most extensive in the UK. The late-lie moss snow-beds (U11 Polytrichum norvegicum – Kiaeria starkei snow-bed and U12 Salix herbacea – Racomitrium heterostichum snow-bed) are the most extensive and well-developed in Britain. The U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb community is also well-represented.
• Creag Meagaidh Highlands and Islands
  Creag Meagaidh has an extensive high plateau with schistose rocks similar to those on Drumochter Hills. The site contains a large area of Siliceous alpine and boreal grasslands with the full range of community types characteristic of the central Highlands. U10 Carex bigelowii – Racomitrium lanuginosum moss-heath is the dominant type on the high plateau, while the species-rich sub-type is also represented as small stands, mostly in association with solifluction terracing. There are large stands of U7 Nardus stricta – Carex bigelowii grass-heath and U8 Carex bigelowii – Polytrichum alpinum sedge-heath is extensive on the summit of Creag Meagaidh. U9 Juncus trifidus – Racomitrium lanuginosum rush-heath is developed locally on exposed ridges. Despite the similarity of rock type, the proportions of the communities present on Creag Meagaidh are different from those on Drumochter Hills. The dominance of Carex – Racomitrium moss-heath on Creag Meagaidh is probably due to a more oceanic climate, while the smaller extent of Nardus – Carex grass-heath and Carex – Polytrichum sedge-heath compared with Drumochter Hills is due to less prolonged snow cover on the high plateau. There are transitions to extensive late-lie moss-dominated snow-bed communities (U11 Polytrichum sexangulare – Kiaeria starkei snow-bed and U12 Salix herbacea – Racomitrium heterostichum snow-bed) and flushed U13 Deschampsia cespitosa – Galium saxatile grassland. U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb community is also represented.
• Drumochter Hills Eastern Scotland, Highlands and Islands
  Drumochter has an extensive high plateau with the fourth-largest extent in the SAC series of Siliceous alpine and boreal grasslands, including the second-largest area of U8 Carex bigelowii – Polytrichum alpinum sedge-heath. Two other sub-types, U10 Carex bigelowii – Racomitrium lanuginosum moss-heath and U7 Nardus stricta – Carex bigelowii grass-heath, are extensive. The site is representative of the central Highlands where schistose rocks predominate, supporting local enrichment of the flora. This contrasts with the wholly acidic granite of the Cairngorms. The comparatively large extent of Carex – Polytrichum sedge-heath is characteristic of the high eastern and central hills. There are especially fine transitions to alpine dwarf-shrub heaths, and unusually the grassland borders extensive high-altitude blanket mire. Late-lie snow-beds of U11 Polytrichum sexangulare – Kiaeria starkei snow-bed and U12 Salix herbacea – Racomitrium heterostichum snow-bed communities are well-developed but are not extensive.
• Eryri/ Snowdonia West Wales and The Valleys
  Snowdonia has the best-developed and most extensive areas of Siliceous alpine and boreal grasslands in Wales and is the largest example of the habitat type south of Scotland. The principal sub-type present is U10 Carex bigelowii – Racomitrium lanuginosum moss-heath, but there are also fragments of U7 Nardus stricta – Carex bigelowii grass-heath. This site is representative of the more impoverished southern variants of the habitat type.
• Fannich Hills Highlands and Islands
  Siliceous alpine and boreal grasslands are represented at Fannich Hills by NVC types U7 Nardus stricta–Carex bigelowii grass-heath, U10 Carex bigelowii–Racomitrium lanuginosum moss-heath, U11 Polytrichum norvegicum–Kiaeria starkei snow-bed, U12 Salix herbacea–Racomitrium heterostichum snow-bed and U14 Alchemilla alpina–Sibbaldia procumbens dwarf-herb community. These types are representative of the higher hills of the western Highlands, and well represent differing conditions of snow-lie. The range of types is similar to other sites in the region but Fannich Hills supports more extensive tracts of the oceanic U10 Carex–Racomitrium moss-heath which covers much of the high plateaux and summits. The species-poor typical sub-community (U10b) with carpets of woolly fringe-moss Racomitrium lanuginosum covering the ground is well-developed. Most significant is the species-rich sub-type of Carex–Racomitrium moss-heath belonging to the Silene acaulis sub-community (U10c), which is exceptionally extensive at Fannich Hills.
  
  The flora of the Siliceous alpine and boreal grasslands is rich and includes many montane species and national rarities such as alpine lady’s-mantle Alchemilla alpina, three-leaved rush Juncus trifidus, dwarf willow Salix herbacea, mountain everlasting Antennaria dioica, spiked wood-rush Luzula spicata, dwarf cudweed Gnaphalium supinum, alpine bistort Persicaria vivipara, moss campion Silene acaulis, cyphel Minuartia sedoides, sibbaldia Sibbaldia procumbens, trailing azalea Loiseleuria procumbens and alpine bearberry Arctostaphylos alpina. The rare mosses Aulacomnium turgidum, Polytrichum sexangulare and Dicranum starkei are also represented. Montane lichens include a number of characteristic species: Solorina crocea, Thamnolia vermicularis, Cetraria islandica and Ochrolechia frigida.
• Lake District High Fells Cumbria
  Siliceous alpine and boreal grasslands are widely distributed through the Lake District High Fells above 700 m. The acidic rocks are of the Borrowdale Volcanic series and Skiddaw Slates. Some of the summits (particularly Helvellyn and Skiddaw) have frequent areas of disturbed ground due to frost-heave and solifluction. The NVC type present is the species-poor U10 Carex bigelowii – Racomitrium lanuginosum moss-heath. Wavy hair-grass Deschampsia flexuosa and sheep’s fescue Festuca ovina dominate the sward, with bilberry Vaccinium myrtillus, woolly fringe-moss Racomitrium lanuginosum, stiff sedge Carex bigelowii, fir clubmoss Huperzia selago and the lichens Cladonia uncialis, C. coccifera, C. squamosa, C. subcervicornis, Cornicularia aculeata and Cetraria islandica. Dwarf willow Salix herbacea, R. lanuginosum and alpine clubmoss Diphasiastrum alpinum can be locally abundant, the latter particularly where there is late snow-lie.
• Loch Maree Complex Highlands and Islands
  The Loch Maree Complex represents Siliceous alpine and boreal grasslands in the highly oceanic and heavily glaciated hills of the north-west Highlands. Both acid and calcareous sub-types are represented at moderately high altitude. The characteristically oceanic U10 Carex bigelowii – Racomitrium lanuginosum moss-heath is the most extensive and well-developed type, and includes both species-poor and species-rich sub-types with arctic-alpines and rare montane mosses well-represented. There is a relatively small representation of the snow-bed communities U7 Nardus stricta – Carex bigelowii grass-heath and U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb community. There are well-developed transitions to snow-beds dominated by the moss Rhytidiadelphus loreus (assignable to U13 Deschampsia cespitosa – Galium saxatile grassland).
• Merrick Kells South Western Scotland
  Merrick Kells holds the best developed areas of Siliceous alpine and boreal grasslands in the Southern Uplands of Scotland. This is the largest area of the habitat type south of the Highlands within the SAC series. Species-poor U10 Carex bigelowii – Racomitrium lanuginosum moss-heath is the main sub-type and is well-developed, with a high cover of woolly fringe-moss Racomitrium lanuginosum. The accompanying U7 Nardus stricta – Carex bigelowii grass-heath is one of the best representations south of the Highlands in terms of vegetation structure and floristics, although small in area. This occurrence of the habitat type is comparable with southern outliers on the hills of England and Wales.
• Moffat Hills South Western Scotland
  Moffat Hills represents Siliceous alpine and boreal grassland in the central Southern Uplands. The main type represented is U10 Carex bigelowii – Racomitrium lanuginosum moss-heath which covers the higher summits, including solifluction ground. This is some of the best-developed Carex – Racomitrium moss-heath occurring south of the Highlands, though loss of Racomitrium cover may have occurred due to grazing. The moss-heath is grassy, and contains much sheep’s-fescue Festuca ovina and wavy hair-grass Deschampsia flexuosa together with the small herb heath bedstraw Galium saxatile. The frequency of these species is probably an indication of nutrient enrichment from grazing sheep. The snow-bed U7 Nardus stricta – Carex bigelowii grass-heath is widespread here, at one of its few sites south of the Highlands.
• Moor House - Upper Teesdale Cumbria, Tees Valley and Durham
  The summit of Cross Fell has the best-developed and most extensive area of Siliceous alpine and boreal grasslands in England. The U10 Carex bigelowii – Racomitrium lanuginosum moss-heath that covers the summit cap has a high cover of woolly fringe-moss Racomitrium lanuginosum.
• North Harris Highlands and Islands
  North Harris represents an outlier of Siliceous and alpine boreal grassland on the Outer Hebrides in the far north-west of the UK. Two NVC types are present (U10 Carex bigelowii – Racomitrium lanuginosum moss-heath and U7 Nardus stricta – Carex bigelowii grass-heath), representing respectively the chionophobous and chionophilous aspects of the habitat in the Outer Hebrides. The mat-grass Nardus snow-beds are only moderately extensive, but Carex – Racomitrium moss-heath has one of its largest extents outside of the Cairngorms, demonstrating its dominance at higher levels in the cool, oceanic climate.
• Strathglass Complex Highlands and Islands
  The Affric-Cannich Hills within Strathglass Complex have the second-largest extent of Siliceous alpine and boreal grasslands in the UK, and are representative of the habitat type in the north-west Highlands. The rocks are generally acidic, with small areas of moderately base-rich rock. The dominant sub-types present are species-poor U10 Carex bigelowii – Racomitrium lanuginosum moss-heath and U7 Nardus stricta – Carex bigelowii grass-heath. Small areas of U8 Carex bigelowii – Polytrichum alpinum sedge-heath and U9 Juncus trifidus – Racomitrium lanuginosum rush-heath are also represented. There are extensive areas of the rarer species-rich Carex – Racomitrium moss-heath chiefly associated with the disturbed ground of solifluction terracing. This is enriched with arctic-alpine vascular plants and rare montane calcicole mosses. Associated communities include the most extensive areas of U13 Deschampsia cespitosa – Galium saxatile grassland in Britain. The moss- and dwarf-herb-dominated late-lie snow-beds (U11 Polytrichum sexangulare – Kiaeria starkei snow-bed, U12 Salix herbacea – Racomitrium heterostichum snow-bed and U14 Alchemilla alpina – Sibbaldia procumbens dwarf-herb community) are well-represented.

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

• Beinn a' Ghlo Eastern Scotland
• Beinn Bhan Highlands and Islands
• Ben Lawers Eastern Scotland
• Ben Lui Eastern Scotland, Highlands and Islands
• Eastern Mournes Northern Ireland
• Foinaven Highlands and Islands
• Glen Coe Highlands and Islands
• Inverpolly Highlands and Islands
• Meall na Samhna Eastern Scotland
• North Pennine Moors Cumbria, North Yorkshire, Northumberland and Tyne and Wear, Tees Valley and Durham
• Trotternish Ridge Highlands and Islands