Habitat account - Natural and semi-natural grassland formations


6230 Species-rich Nardus grassland, on siliceous substrates in mountain areas (and submountain areas in continental Europe)  * Priority feature

Background to selection

Distribution of SACs/SCIs/cSACs with habitat 6230 Species-rich Nardus grassland, on siliceous substrates in mountain areas (and submountain areas in continental Europe).  Click image for enlarged map.
Distribution of SACs/SCIs/cSACs with habitat 6230 Species-rich Nardus grassland, on siliceous substrates in mountain areas (and submountain areas in continental Europe). Click image for enlarged map.

Description and ecological characteristics

 

Species-rich Nardus grasslands tend to develop where there is flushing through base-rich strata on siliceous bedrock. These may include moderately base-rich metamorphic and igneous rocks. The soils have an acidic pH (<7.0 and mainly <6.0) and are derived from bedrocks with at least some silica. Species-rich Nardus grasslands on limestone are excluded from the definition of this Annex I habitat because limestone lacks silica. The altitudinal range varies from near sea level to an upper limit of between 800 and 900 m. Species-rich Nardus grasslands are important because they support a wide range of species, including Atlantic, sub-Atlantic and arctic-alpine plants and invertebrates.

 

Species present in the grassland tend to be mesophilic. Swards are closely grazed and consist of a complex mosaic of grasses, small herbs and bryophytes. As defined by the NVC, two main types of species-rich Nardus grasslands occur in the UK:

 

     

  • CG10  Festuca ovina – Agrostis capillaris – Thymus praecox grassland
  • CG11  Festuca ovina – Agrostis capillaris – Alchemilla alpina grassland

 

As noted above, only forms of these two communities on siliceous substrates are included within this Annex I category. More species-rich sub-types of NVC communities U4 Festuca ovina – Agrostis capillaris – Galium saxatile grassland and U5 Nardus stricta – Galium saxatile grassland are also included within the habitat definition. This especially applies to the Carex panicea – Viola riviniana sub-community of U5. Variation within these communities is related chiefly to altitude, oceanicity, soil moisture and the extent of flushing with base-rich water. At high altitude there is a greater representation of arctic-alpine plants, and the habitat can be transitional floristically to and grade into 6170 Alpine and subalpine calcareous grasslands. Floristically richer areas develop where there is a concentration of base-rich or calcareous strata, giving suitable conditions for the rarer base- or calcium-loving species. In such situations, especially where outcrops of limestone occur, transitions to 6210 Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia) may develop.

 

Low-altitude variants of species-rich Nardus grasslands are extensive in the Western Isles and the extreme western Highlands but also occur locally in the eastern Highlands. In the west, where oceanic influences predominate, communities are characterised by the presence of Atlantic or sub-Atlantic species, including both vascular plants and bryophytes. Some examples contain maritime species, and may show transitions to sub-maritime grasslands.

 

Floristically the two main NVC types included in species-rich Nardus grasslands are closely related. They are characterised by a mix of grasses, typically sheep’s-fescue Festuca ovina, common bent Agrostis capillaris, sweet vernal-grass Anthoxanthum odoratum, mat-grass Nardus stricta, red fescue Festuca rubra, heath grass Danthonia decumbens and wavy-hair grass Deschampsia flexuosa. There is a wide range of small dicotyledonous herbs, including heath bedstraw Galium saxatile, tormentil Potentilla erecta, common dog-violet Viola riviniana, wild thyme Thymus polytrichus, ribwort plantain Plantago lanceolata and harebell Campanula rotundifolia. The main difference between the two communities is the frequency and abundance of alpine lady’s-mantle Alchemilla alpina and the frequency of bilberry Vaccinium myrtillus in Festuca – Agrostis – Alchemilla grassland, and the high frequency of selfheal Prunella vulgaris in Festuca – Agrostis – Thymus grassland. The latter community tends to occur more extensively at lower altitudes, where it supports more lowland species than the former. However, both types extend to the same maximum altitude, and both types are enriched with arctic-alpines at the higher end of their altitudinal range. Both communities also show variation related to soil moisture. Herbs such as white clover Trifolium repens, field wood-rush Luzula campestris, heath speedwell Veronica officinalis, yarrow Achillea millefolium, mountain everlasting Antennaria dioica, bitter-vetch Lathyrus linifolius, field gentian Gentianella campestris, pill sedge Carex pilulifera and spring sedge Carex caryophyllea are characteristic of drier swards. Species such as flea sedge C. pulicaris, carnation sedge C. panicea, pale sedge C. pallescens, grass of parnassus Parnassia palustris, purging flax Linum catharticum and quaking grass Briza media occur in areas with high soil moisture.

 

At high altitudes, where the swards are more flushed, the arctic-alpines yellow saxifrage Saxifraga aizoides, purple saxifrage S. oppositifolia, alpine meadow-rue Thalictrum alpinum and alpine bistort Persicaria vivipara may be frequent. Other arctic-alpines or northern species that are represented include the lady’s-mantles Alchemilla filicaulis ssp. filicaulis and A. wichurae, hair sedge Carex capillaris, rock sedge C. rupestris, Scottish asphodel Tofieldia pusilla, alpine mouse-ear Cerastium alpinum, alpine clubmoss Diphasiastrum alpinum, northern bedstraw Galium boreale, spiked wood-rush Luzula spicata, cyphel Minuartia sedoides, globeflower Trollius europaeus, alpine cinquefoil Potentilla crantzii, sibbaldia Sibbaldia procumbens and mountain pansy Viola lutea. At low altitudes in the west there may be representation of maritime species, such as sea plantain Plantago maritima, buck’s-horn plantain P. coronopus and wild carrot Daucus carota. Also in the west, Atlantic or oceanic bryophytes such as Herbertus stramineus, Plagiochila spinulosa, Scapania gracilis and Mastigophora woodsii may occur, and more generally there are calcicole species, such as Barbilophozia lycopodioides, Aulacomnium turgidum and Schistidium apocarpum. Other notable bryophytes, such as Lophozia obtusa, have also been recorded in this habitat.

European status and distribution

 

Species-rich Nardus grasslands are rare in mainland Europe, being restricted to the cooler areas of mountain regions. They are found mainly in the more central regions of continental Europe and the Atlantic Biogeographical Region.

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

 

Species-rich Nardus grasslands are widely-developed in the UK, especially in western Scotland.

Site selection rationale

 

The SAC series takes account of the UK’s special responsibility for this priority habitat type. The sites selected contain the most extensive examples of the habitat and those with the best community structure and function. Selection has also encompassed the geographical range and ecological variation of this habitat type in the UK. The habitat type is best-developed in western Scotland, and the SAC series reflects this distribution.


Site accounts

Ardmeanach Highlands and Islands
Ardmeanach is one of five sites representing the range of low-altitude sub-types of species-rich Nardus grasslands on the oceanic west coast of Scotland. Ardmeanach is one of the most westerly and maritime of the sites selected. The species-rich Nardus grasslands occur extensively as short swards on a large basalt escarpment. The most extensive community represented is CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland, but on more northerly-facing slopes this is replaced by CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland. A range of sub-types of these two communities is represented. Sub-maritime variants of the habitat are developed on the lower parts of the escarpment, with the maritime species sea plantain Plantago maritima, buck’s-horn plantain Plantago coronopus and wild carrot Daucus carota. Dry and wetter sub-types are both represented. There is a high plant diversity, including lowland species, such as common centaury Centaurium erythraea, fragrant agrimony Agrimonia procera, red clover Trifolium pratense and false-brome Brachypodium sylvaticum, as well as upland, northern species, such as globeflower Trollius europaeus, the lady’s-mantle Alchemilla glabra and northern bedstraw Galium boreale. There are transitions to maritime grassland and species-rich dry Calluna heath.
Beinn a' Ghlo Eastern Scotland
Beinn a’Ghlo is an example of species-rich Nardus grasslands characteristic of the eastern Scottish Highlands. Beinn a’Ghlo has a large area of species-rich Nardus grassland, the second most extensive area in the site series, developed on schistose rocks and grades to 6210 Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia) on limestone. Both CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland and CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland are well-represented throughout the altitudinal range of the habitat type on the site (300750 m). The moderate altitude limits the range of arctic-alpines. There is a good representation of more widespread species, including the lady’s-mantle Alchemilla filicaulis, alpine bistort Persicaria vivipara, purple saxifrage Saxifraga oppositifolia, sibbaldia Sibbaldia procumbens, mountain pansy Viola lutea and hair sedge Carex capillaris. A few rarer arctic-alpines, such as yellow oxytropis Oxytropis campestris and alpine meadow-grass Poa alpina, are also present.
Beinn Iadain and Beinn na h' Uamha Highlands and Islands
Beinn Iadain and Beinn na h’Uamha is representative of species-rich Nardus grasslands in the western Scottish Highlands. The species-rich Nardus grasslands occur on basalt, and include CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland and CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland, both of which are well-represented. The grasslands are extensive, though grazing pressures are high, with mostly only the smaller grazing-tolerant herbs represented. There are frequent occurrences of the more common and widespread arctic-alpine and northern species, including alpine lady’s-mantle Alchemilla alpina, the lady’s-mantles A. glabra and A. filicaulis, mossy saxifrage Saxifraga hypnoides, mountain everlasting Antennaria dioica, alpine meadow-rue Thalictrum alpinum, northern bedstraw Galium boreale and viviparous sheep’s-fescue Festuca vivipara. A sub-maritime form with sea plantain Plantago maritima also occurs. On shady slopes there is a mossy form with the Atlantic bryophytes Breutelia chrysocoma, Racomitrium ellipticum, Scapania gracilis and Plagiochila spinulosa, as well as the scarce Lophozia obtusa.
Ben Heasgarnich Eastern Scotland, Highlands and Islands
Ben Heasgarnich is representative of species-rich Nardus grasslands on the base-rich schists of the Breadalbane range in the southern Scottish Highlands. Ben Heasgarnich has an extensive area of species-rich Nardus grassland. With Meall na Samhna and Ben Lui it contains the most species-rich and diverse examples of high-altitude grassland, and there is a rich arctic-alpine flora, including alpine bistort Persicaria vivipara, sheathed sedge Carex vaginata, the lady’s-mantle Alchemilla filicaulis and hair sedge Carex capillaris. There are transitions to floristically-rich 6170 Alpine and subalpine calcareous grasslands. These Nardus-rich grasslands are notable for supporting a large population of the mountain ringlet butterfly Erebia epiphron.
Cairngorms Highlands and Islands, North Eastern Scotland
The Cairngorms is representative of the most eastern forms of species-rich Nardus grasslands in the UK. Both CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland and CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland are well-represented through an altitudinal range of 300750 m, associated with calcareous and basic schists. There are particularly extensive examples at Inchrory on calcareous schist, but the community occurs elsewhere, notably at Craig an Dail Beag and in Glen Feshie. Swards also occur on alluvial soils in the bottoms of many of the main glens. At Inchrory both northern and southern species are well represented, including species characteristic of both species-rich Nardus and 6210 Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia). The most abundant of the southern species is common rockrose Helianthemum nummularium; others include burnet saxifrage Pimpinella saxifraga and blue fleabane Erigeron acer. Green-winged orchid Orchis morio has also been recorded. Northern species include yellow saxifrage Saxifraga aizoides and hair sedge Carex capillaris, both of which are locally abundant in flushed grasslands at Inchrory. Mountain everlasting Antennaria dioica, alpine meadow-rue Thalictrum alpinum, alpine saw-wort Saussurea alpina and the rare alpine milk-vetch Astragalus alpinus and alpine cinquefoil Potentilla crantzii, are also present.
Glen Coe Highlands and Islands
Glen Coe is the most southerly of five sites representing species-rich Nardus grasslands in the western Highlands, ranging up to the far north-west. On this site, species-rich Nardus grassland occurs on base-rich igneous rocks, calcareous-schists and base-enriched alluvial soils, and is found from moderately high to high altitudes. Both CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland and CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland are well-represented. There is an unusual wet flushed grassland with an abundance of sedges, such as carnation sedge Carex panicea and flea sedge C. pulicaris, purging flax Linum catharticum, grass-of-Parnassus Parnassia palustris, fragrant orchid Gymnadenia conopsea, lousewort Pedicularis sylvatica and sea plantain Plantago maritima. The grasslands are enriched locally with the arctic-alpines yellow saxifrage Saxifraga aizoides, purple saxifrage S. oppositifolia, alpine meadow-rue Thalictrum alpinum and hair-sedge C. capillaris. Other northern species occurring more generally are viviparous sheep’s-fescue Festuca vivipara, northern bedstraw Galium boreale, lady’s-mantle Alchemilla glabra and mountain everlasting Antennaria dioica. There are transitions to western herb-rich bilberry Vaccinium myrtillus heath.
Lendalfoot Hills Complex South Western Scotland
Lendalfoot Hills is one of five sites representing relatively low-altitude oceanic species-rich Nardus grasslands in western Scotland. This is the most southerly site where maritime species occur inland. The only NVC type present is CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland. This occurs both in a dry form with yarrow Achillea millefolium, white clover Trifolium repens, spring sedge Carex caryophyllea and lady’s-bedstraw Galium verum, and a wet flushed form with flea sedge C. pulicaris, sea plantain Plantago maritima and purging flax Linum catharticum. Mixed forms are widespread. The low-altitude flora is species-rich, and includes crested hair-grass Koeleria macrantha, meadow oat-grass Helictotrichon pratense, common rock-rose Helianthemum nummularium and tufted vetch Vicia cracca, giving a grassland with floristic elements that are more usually associated with 6210 Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia). The northern flora is less well-developed, with a lady’s mantle Alchemilla glabra, northern bedstraw Galium boreale and bitter-vetch Lathyrus linifolius present. The underlying rocks are of serpentine and other ultra-basic rocks, and the grasslands occur in unusual mosaics with black bog-rush Schoenus nigricans-rich 4010 Northern Atlantic wet heaths with Erica tetralix and 7230 Alkaline fens.
Meall na Samhna Eastern Scotland
Meall na Samhna is an example of species-rich Nardus grasslands characteristic of the Breadalbane range of the southern Scottish Highlands. Species-rich Nardus grassland occurs widely below crags at moderately high to high altitude on calcareous-schist rocks. CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland is the main community present. The site supports a rich flora of characteristic arctic-alpine species, including alpine meadow-rue Thalictrum alpinum, alpine bistort Persicaria vivipara, purple saxifrage Saxifraga oppositifolia, alpine mouse-ear chickweed Cerastium alpinum, lady’s mantle Alchemilla filicaulis, mossy saxifrage Saxifraga hypnoides, sibbaldia Sibbaldia procumbens and dwarf cudweed Gnaphalium supinum. There are widely-developed transitions to 6170 Alpine and subalpine calcareous grasslands and species-poor forms of Nardus grassland.
Rum Highlands and Islands
Rum is one of five sites on the oceanic west coast of Scotland representing low- to moderately high-altitude oceanic sub-types of species-rich Nardus grasslands. This site is characteristic of the communities found to the north and west of the range. Extensive herb-rich grasslands have developed below cliffs of ultra-basic rocks along the coast. The grasslands occur from near sea level to about 750 m. Both CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland and CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland are well-represented. The stands are more scattered and more varied ecologically than on the basalt sites elsewhere in Scotland, but overall the flora is similar. Many uncommon but characteristic species are present, including mountain everlasting Antennaria dioica, bitter-vetch Lathyrus linifolius, milkwort Polygala vulgaris, field gentian Gentianella campestris, small-white orchid Pseudorchis albida, pale sedge Carex pallescens and lousewort Pedicularis sylvatica. Arctic-alpine and northern species include alpine bistort Persicaria vivipara, alpine meadow-rue Thalictrum alpinum, alpine lady’s mantle Alchemilla alpina and viviparous sheep’s-fescue Festuca vivipara. There is a range of transitions to maritime grassland, calcareous grasslands, herb-rich 4030 European dry heaths and open communities on ultra-basic rocks.
Trotternish Ridge Highlands and Islands
Trotternish Ridge is one of five sites on the oceanic west coast of Scotland representing species-rich Nardus grasslands. It is the most northerly site and is more upland in character than the other sites selected. Trotternish Ridge has the most extensive tracts of species-rich Nardus grasslands in the UK. These occur along the length of an extensive basalt escarpment. Both CG10 Festuca ovinaAgrostis capillarisThymus praecox grassland and CG11 Festuca ovinaAgrostis capillarisAlchemilla alpina grassland are well-represented, mainly occurring as drier forms on well-drained slopes. Overall the grasslands are rich in both vascular plants and bryophytes, though heavy grazing on the slopes may be limiting species-richness. The flora is enriched by arctic-alpines, including sibbaldia Sibbaldia procumbens, the lady’s-mantle Alchemilla wichurae, mossy saxifrage Saxifraga hypnoides and cyphel Minuartia sedoides. The grasslands are notable for their bryophyte flora, which includes Atlantic species such as Scapania gracilis, Racomitrium ellipticum, Breutelia chrysocoma and Plagiochila spinulosa, occurring with calcicole mosses such as Aulacomnium turgidum and Schistidium apocarpum.

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

Beinn Dearg Highlands and Islands
Ben Lawers Eastern Scotland
Ben Lui Eastern Scotland, Highlands and Islands
Ben Nevis Highlands and Islands
Binevenagh Northern Ireland
Caenlochan Eastern Scotland, North Eastern Scotland
Craigengar Eastern Scotland, South Western Scotland
Drumochter Hills Eastern Scotland, Highlands and Islands
Eryri/ Snowdonia West Wales and The Valleys
Foinaven Highlands and Islands
Lake District High Fells Cumbria
North Antrim Coast Northern Ireland
 

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