Habitat account - Natural and semi-natural grassland formations


6430 Hydrophilous tall herb fringe communities of plains and of the montane to alpine levels 

Background to selection

Distribution of SACs/SCIs/cSACs with habitat 6430 Hydrophilous tall herb fringe communities of plains and of the montane to alpine levels.  Click image for enlarged map.
Distribution of SACs/SCIs/cSACs with habitat 6430 Hydrophilous tall herb fringe communities of plains and of the montane to alpine levels. Click image for enlarged map.

Description and ecological characteristics

 

This habitat type is typically found on ungrazed upland cliff ledges, occasionally extending on to open ground, and is restricted to base-rich substrates and somewhat sheltered situations. This is one of the few near-natural habitats remaining in Britain and frequently occurs in intimate mosaics with other Annex I habitat types in these ungrazed, or very lightly grazed, situations. It provides a refuge for rare, grazing-sensitive, montane plants. Closely related vegetation types, such as the hay meadows of the Pennines, conform to Annex I type 6520 Mountain hay meadows.

 

Hydrophilous tall herb fringe communities is a species-rich habitat corresponding to NVC type U17 Luzula sylvatica – Geum rivale tall-herb community. It is characterised by the abundance of a species-rich mix of tall, broad-leaved herbs, most of which are otherwise rare in the uplands owing to their sensitivity to grazing. These include species such as great wood-rush Luzula sylvatica, wild angelica Angelica sylvestris, roseroot Sedum rosea, wood crane’s-bill Geranium sylvaticum, water avens Geum rivale and globe-flower Trollius europaeus. Some of these species, such as the last three, can be found as very impoverished, non-flowering specimens in grazed pastures adjacent to cliff refuges. This demonstrates the restrictive effects of grazing and the potential for expansion of the habitat. L. sylvatica is one of the more tolerant species, both with respect to soil conditions and grazing impacts, and occurs in a variety of communities other than this one.

 

Variation within the habitat type is related chiefly to geographical position, altitude, and soil conditions and rock type. Stands in the Scottish Highlands are richer in northern species, while stands further south have species of a more southerly distribution. In the Highlands stands at high-altitude are enriched by scarce arctic-alpine plants, such as holly fern Polystichum lonchitis, alpine saw-wort Saussurea alpina, black alpine-sedge Carex atrata and alpine cinquefoil Potentilla crantzii. The rarer species tend to occur on the more calcareous or base-rich ledges at high altitude and some species prefer wetter soils.

European status and distribution

 

The habitat type occurs widely across the EU but is very localised in its distribution.

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

 

In the UK this is a very rare habitat. Its total extent is difficult to estimate but is probably much less than 1,000 ha. It is most widespread in the Scottish Highlands, becoming more fragmentary on the Scottish islands and further south in the UK.

Site selection rationale

 

The sites selected cover the geographical range and ecological variation of the habitat type and ensure protection of a high proportion of the total UK resource. The SAC series includes the most diverse examples and those with the best-developed vegetation structure and function, taking into account altitudinal range, floristic diversity and geographic variation. Larger sites with a range of rock types and a large number of ungrazed rock ledges have been favoured, as this ensures inclusion of the maximum extent of this very localised habitat type. Sites holding rich assemblages of rare species have also been selected preferentially.


Site accounts

Ardmeanach Highlands and Islands
The upper base-rich basalt cliffs of Ardmeanach support well-developed examples of hydrophilous tall herb fringe communities in the relatively mild south-west of Scotland. The stands represent some of the best examples known on basalt crags and in south-west Scotland generally. The flora is unusual in the association of contrasting geographical elements, such as the southern Atlantic liverwort Marchesinia mackaii together with northern and arctic-alpine species such as northern bedstraw Galium boreale, moss campion Silene acaulis and alpine lady’s-mantle Alchemilla alpina. Characteristic species include globe-flower Trollius europaeus, wild angelica Angelica sylvestris and lady’s-mantle Alchemilla glabra. Unusually, woodland species such as dog’s mercury Mercurialis perennis and false brome Brachypodium sylvaticum occur, perhaps because of the low altitude of the cliffs.
Beinn Bhan Highlands and Islands
Hydrophilous tall herb fringe communities are represented at Beinn Bhan by what is believed to be the largest single stand in the UK of the tall herb community corresponding to NVC type U17 Luzula sylvatica–Geum rivale. This habitat is developed where there is seepage through the soil on a large ledge on the Torridonian sandstone cliffs in Coire na Poite. The ledge is relatively inaccessible and therefore ungrazed. The main species present are wild angelica Angelica sylvestris, marsh marigold Caltha palustris, marsh hawk’s-beard Crepis paludosa, meadow buttercup Ranunculus acris, water avens Geum rivale, meadowsweet Filipendula ulmaria, globeflower Trollius europaeus and common valerian Valeriana officinalis, representing a wetter type than is usual for this community. One of the more notable species of the community represented is the scarce alpine saw-wort Saussurea alpina, which is characteristic of high-altitude stands in the Highlands.
Beinn Dearg Highlands and Islands
Beinn Dearg is representative of hydrophilous tall herb fringe communities in north-west Scotland. The habitat type is developed at high altitudes on calcareous schist. It is the best site for this habitat type in this part of Scotland, because of the extensive development of tall-herb vegetation on ledges across the site and the high species diversity. Characteristic species include roseroot Sedum rosea, globeflower Trollius europaeus, water avens Geum rivale and wood crane’s-bill Geranium sylvaticum, mixed with downy willow Salix lapponum in places. Many of the rarer arctic-alpines associated with this habitat are present, including holly-fern Polystichum lonchitis, alpine saw-wort Saussurea alpina, black alpine-sedge Carex atrata, arctic mouse-ear Cerastium arcticum and rock whitlowgrass Draba norvegica.
Ben Heasgarnich Eastern Scotland, Highlands and Islands
Ben Heasgarnich in the Breadalbane range in the southern Scottish Highlands is representative of hydrophilous tall herb fringe communities up to high altitudes on calcareous schist. Diverse and well-developed examples of the habitat type occur across the site, with rarer arctic-alpines including rock whitlowgrass Draba norvegica, alpine mouse-ear Cerastium alpinum and black alpine-sedge Carex atrata. The site is unusual because, in places, plants characteristic of the ledge flora, such as lady’s-mantle Alchemilla glabra, water avens Geum rivale, wood crane’s-bill Geranium sylvaticum and globeflower Trollius europaeus, are found in moist grassland below the crags.
Ben Lawers Eastern Scotland
Ben Lawers is located in the Breadalbane range in the southern Scottish Highlands where hydrophilous tall herb fringe communities occur up to high altitudes on ledges of calcareous schist. Examples of the community occur in a number of localities across the site and are relatively extensive in places. There is a diverse flora, which includes characteristic species such as roseroot Sedum rosea, water avens Geum rivale, wild angelica Angelica sylvestris, wood crane’s-bill Geranium sylvaticum, melancholy thistle Cirsium heterophyllum and globeflower Trollius europaeus. A number of rare arctic-alpines are present in the habitat type on this site, including the rock whitlowgrass Draba norvegica, alpine cinquefoil Potentilla crantzii, black alpine-sedge Carex atrata, alpine meadow-grass Poa alpina and alpine forget-me-not Myosotis alpestris.
Ben Lui Eastern Scotland, Highlands and Islands
Ben Lui in the Breadalbane range in the southern Scottish Highlands is representative of hydrophilous tall herb fringe communities occurring on calcareous schist up to high altitude. Ben Lui has a large number of examples of this habitat type, distributed widely across the site. Structure and function are well-developed and the communities are diverse. Characteristic species include roseroot Sedum rosea, wild angelica Angelica sylvestris, melancholy thistle Cirsium heterophyllum and globeflower Trollius europaeus, and a number of rare arctic-alpines, including alpine bartsia Bartsia alpina, alpine saw-wort Saussurea alpina, the lady’s-mantle Alchemilla wichurae, black alpine-sedge Carex atrata and rock sedge C. rupestris. Together with Glen Coe, Ben Lui represents the habitat type in the wetter and more oceanic west, where there is a greater frequency of species associated with wetter silts and dripping ledges, such as marsh hawk’s-beard Crepis paludosa, grass-of-Parnassus Parnassia palustris and bog orchid Hammarbya palustris. There is also a great luxuriance of ferns, including oak fern Gymnocarpium dryopteris, lemon-scented fern Oreopteris limbosperma, beech fern Phegopteris connectilis, holly-fern Polystichum lonchitis and hard shield-fern Polystichum aculeatum. In places hydrophilous tall herb fringe communities occur in an intimate mosaic with 4080 Sub-Arctic Salix spp. scrub, and there are well-developed transitions between them. Most of the species of Ben Lawers are present, except for some of the rarer montane species. The extent of the habitat type is at Ben Lui is similar to that on Ben Lawers.
Caenlochan Eastern Scotland, North Eastern Scotland
Caenlochan is the most easterly site selected and is representative of hydrophilous tall herb fringe communities in the eastern Highlands. The habitat type is widely-developed across the site and is found on ledges of calcareous and more acid schists with a wide altitudinal range, including very high altitudes (550870 m). Caenlochan is considered to have the greatest extent of this habitat type in the UK. There is an extremely diverse and well-developed montane flora containing a range of characteristic species, such as roseroot Sedum rosea, red campion Silene dioica, water avens Geum rivale, globeflower Trollius europaeus and wood crane’s-bill Geranium sylvaticum. Rarer species include black alpine-sedge Carex atrata, alpine gentian Gentiana nivalis, alpine fleabane Erigeron borealis, alpine mouse-ear Cerastium alpinum and alpine cinquefoil Potentilla crantzii. A very rare species that occurs on more acid ledges and is not represented on any other site in the series is alpine blue-sow-thistle Cicerbita alpina. The ledges at lower altitude have woodland species, such as wood anemone Anemone nemorosa and dog’s mercury Mercurialis perennis, which are usually rare in the habitat type.
Creag Meagaidh Highlands and Islands
Creag Meagaidh has examples of hydrophilous tall herb fringe communities representative of Moine schist rocks in the central Highlands. The habitat is moderately well-developed and largely confined to ungrazed cliff ledges but unusually occurs in at least one boulder field. The characteristic species of the community are well-represented, and include roseroot Sedum rosea, wild angelica Angelica sylvestris, lady’s mantle Alchemilla glabra, globeflower Trollius europaeus, great wood-rush Luzula sylvatica and water avens Geum rivale. Wet or moist ground supports scurvygrass Cochlearia officinalis, marsh-marigold Caltha palustris and common valerian Valeriana officinalis. Unusually there are tall herb ledges at low altitude with species such as wood vetch Vicia sylvatica and melancholy thistle Cirsium heterophyllum. The habitat grades into 4080 Sub-Arctic Salix spp. scrub, and downy willow Salix lapponum occurs among tall herbs on some ledges.
Eryri/ Snowdonia West Wales and The Valleys
Snowdonia is the most southerly site selected and contains the most extensive and diverse examples of hydrophilous tall herb fringe communities in Wales. Fragmentary stands of the habitat type occur on pumice tuff and other base-enriched igneous rocks at a range of altitudes throughout the site. The vegetation is floristically somewhat impoverished compared with Scottish examples but includes many of the species found further north, such as globe-flower Trollius europaeus, wild angelica Angelica sylvestris and holly-fern Polystichum lonchitis. It is important as a southern outlier for arctic-alpines such as alpine saw-wort Saussurea alpina and black alpine-sedge Carex atrata. There are also some southern species, which are absent further north, for example Welsh poppy Meconopsis cambrica.
Foinaven Highlands and Islands
Foinaven is representative of hydrophilous tall herb fringe communities in the north of Scotland, where the habitat type is rare. It is the best example in this area because of the extensive development of the communities and the range of unusual types of rocks on which they occur, such as calcareous serpulite grits and fucoid beds, as well as calcareous schists. Because of the low altitude the flora is not as rich as at sites further south in the Highlands. Characteristic species include the lady’s-mantle Alchemilla glabra, wild angelica Angelica sylvestris, water avens Geum rivale, globeflower Trollius europaeus and roseroot Sedum rosea. Rarer arctic-alpines on the site include alpine saw-wort Saussurea alpina, alpine saxifrage Saxifraga nivalis and holly-fern Polystichum lonchitis.
Glen Coe Highlands and Islands
Glen Coe, in the western Highlands, contains hydrophilous tall herb fringe communities at a range of altitudes in an oceanic climate on igneous rocks, including calcareous andesites and limestone, which support the richest flora. This habitat type shows well-developed structure and high species diversity. Characteristic species include roseroot Sedum rosea, wild angelica Angelica sylvestris, common valerian Valeriana officinalis, hogweed Heracleum sphondylium, mountain melick Melica nutans, lesser meadow-rue Thalictrum minus and melancholy thistle Cirsium heterophyllum. The habitat type is similar to that on Ben Lui, with a good representation of ferns, including brittle bladder-fern Cystopteris fragilis, polypody Polypodium vulgare, beech fern Phegopteris connectilis and holly-fern Polystichum lonchitis. Some crags have running water with an unusual abundance of common scurvygrass Cochlearia officinalis, and other species of wet crags are well-represented, including opposite-leaved golden-saxifrage Chrysosplenium oppositifolium, grass-of-Parnassus Parnassia palustris and marsh hawk’s-beard Crepis paludosa. On Meall Mór there are transitions to 4080 Sub-Arctic Salix spp. scrub with whortle-leaved willow Salix myrsinites.
Lake District High Fells Cumbria
This site is representative of hydrophilous tall herb fringe communities in England. Although the communities are not as rich in species as high-altitude sites in the Scottish Highlands, a representative montane flora is present including a number of rare arctic-alpine species. The Lake District High Fells include the largest continuous areas of land above 760 m in the Lake District. Rocks of the Borrowdale Volcanic Series form the underlying geology of much of the area. Although these rocks are generally acidic, many cliffs are particularly rich in base minerals and weather to produce pockets of fertile soil. Many of the high-altitude gills also support this vegetation type. It is these areas of moist, basic soils that support species-rich tall herb vegetation. It is these areas of moist, basic soils that support species-rich tall herb vegetation. Tall herb ledge communities are mainly found in Helvellyn and Fairfield (probably one of the most important areas in England for calcareous montane flora found on the extensive cliff ledges), Honister Crag, Scafell Pikes, Pillar and Ennerdale Fells and Wasdale Screes, with scattered species rich ledges elsewhere. The tall herb communities are characterised by wood crane’s-bill Geranium sylvaticum, wild angelica Angelica sylvestris, water avens Geum rivale, and globeflower Trollius europaeus. Often associated with these ledges but also found on the bare outcrops and ledges are many montane and northern species such as roseroot Sedum rosea and mountain sorrel Oxyria digyna. Scarcer plants that occasionally occur throughout include alpine saw-wort Saussurea alpina, alpine meadow rue Thalictrum alpinum. The gill ledges support a wide range of ferns including lemon-scented fern Oreopteris limbosperma, beech fern Phegopteris connectilis and oak fern Gymnocarpium dryopteris. A number of rare arctic-alpine species occur, including alpine cinquefoil Potentilla crantzii and alpine meadow grass Poa alpina, black alpine sedge Carex atrata and alpine saxifrage Saxifraga nivalis at Helvellyn and Fairfield. Buttermere Fells is also a locality for the rare alpine catchfly Lychnis alpina.
Moor House - Upper Teesdale Cumbria, Tees Valley and Durham
Moor House – Upper Teesdale comprises an area of mixed geology made up of carboniferous sandstones, mudstone and limestones. The combination of acidic and base-rich soil has given rise to an important range of vegetation types that has also been influenced by climatic conditions on this, the highest part of the Pennines. Hydrophilous tall herb fringe communities occur on wet ledges in base-rich rocks, which are inaccessible to grazing livestock. One of the most extensive stands is on a tributary of Little Gill, and examples also occur at Lady Gill, Greencastle, High Cup Nick and Mickle Fell. Typical species that occur in these localities include great wood-rush Luzula sylvatica, wood crane’s-bill Geranium sylvaticum, water avens Geum rivale, lady’s-mantle Alchemilla glabra, wild angelica Angelica sylvestris and roseroot Sedum rosea.

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

Beinn Iadain and Beinn na h' Uamha Highlands and Islands
Ben Alder and Aonach Beag Highlands and Islands
Ben Nevis Highlands and Islands
Ben Wyvis Highlands and Islands
Brecon Beacons/ Bannau Brycheiniog East Wales
Cadair Idris West Wales and The Valleys
Cairngorms Highlands and Islands, North Eastern Scotland
Drumochter Hills Eastern Scotland, Highlands and Islands
Durness Highlands and Islands
Loch Maree Complex Highlands and Islands
Meall na Samhna Eastern Scotland
Moffat Hills South Western Scotland
Rum Highlands and Islands
Strathglass Complex Highlands and Islands
Trotternish Ridge Highlands and Islands
 

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