Habitat account - Raised bogs and mires and fens


7240 Alpine pioneer formations of the Caricion bicoloris-atrofuscae  * Priority feature

Background to selection

Distribution of SACs/SCIs/cSACs with habitat 7240 Alpine pioneer formations of the Caricion bicoloris-atrofuscae.  Click image for enlarged map.
Distribution of SACs/SCIs/cSACs with habitat 7240 Alpine pioneer formations of the Caricion bicoloris-atrofuscae. Click image for enlarged map.

Description and ecological characteristics

 

Alpine pioneer formations of the Caricion bicoloris-atrofuscae is a type of flush mire that occurs only at high altitude. The characteristic plant communities colonise open substrates that are constantly flushed by surface seepage of cold, base-rich water. They are amongst the few remaining natural plant communities in the UK and are maintained by harsh climatic and soil conditions.

 

The vegetation consists of mixtures of small sedges, rushes, small herbs and bryophytes, and includes many arctic-alpine species. High-altitude stands only, of four NVC types, enriched by arctic-alpine elements, fall within the definition of this habitat type:

 

     

  • M10  Carex dioica – Pinguicula vulgaris mire
  • M11  Carex demissa – Saxifraga aizoides mire
  • M12  Carex saxatilis mire
  • M34  Carex demissa – Koenigia islandica flush

 

There is variation in this habitat because of differences in altitude, geographic location, length of snow-lie, nature of the substrate, and the amount of water flushing the communities. The habitat is characterised by the presence of a number of rare species. These include scorched alpine-sedge Carex atrofusca, bristle sedge C. microglochin, alpine rush Juncus alpinoarticulatus, chestnut rush J. castaneus, two-flowered rush J. biglumis, three-flowered rush J. triglumis, false sedge Kobresia simpliciuscula and Scottish asphodel Tofieldia pusilla. Other uncommon species may occur, such as hair sedge Carex capillaris, sheathed sedge C. vaginata and variegated horsetail Equisetum variegatum. There is a range of calcicolous mosses, some of which are rare.

 

A number of commoner species are also characteristic of the habitat. These include yellow sedge Carex viridula, carnation grass C. panicea, flea sedge C. pulicaris, russet sedge C. saxatilis, jointed rush Juncus articulatus, common butterwort Pinguicula vulgaris, yellow saxifrage Saxifraga aizoides, alpine bistort Persicaria vivipara, alpine meadow-rue Thalictrum alpinum and the moss Blindia acuta.

 

This habitat usually forms mosaics and shows complex transitions to other upland Annex I habitat types.

European status and distribution

 

This habitat occurs in the Atlantic, Alpine and Boreal Biogeographical Regions.

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

 

In the UK this priority habitat is rare and is largely restricted to the Scottish Highlands, where it is relatively widespread. There are southern outliers in northern England and north Wales. The habitat is rarely extensive but is important as a habitat for some of the rarest plant species in the UK, which characterise this habitat type.

Site selection rationale

 

Site selection has covered the range of ecological and geographical variation of the habitat type. The largest and most diverse examples, and those with best-developed structure and function, have been selected. Large upland sites are most likely to contain a variety of different flush types and include the most extensive populations of the commoner species. Preference has also been given to localities holding strong populations of rare arctic-alpine species. Most sites are situated in the Scottish Highlands but two southern outliers have also been included.


Site accounts

Beinn a' Ghlo Eastern Scotland
Beinn a’Ghlo is representative of flushes at moderate altitude in the eastern Highlands. Open flushes of M11 Carex demissa – Saxifraga aizoides mire are frequent, and species include yellow saxifrage Saxifraga aizoides, Scottish asphodel Tofieldia pusilla, three-flowered rush Juncus triglumis and alpine rush J. alpinoarticulatus. The site is of particular interest because of the transitions between alpine pioneer flushes and 7230 Alkaline fens at moderate altitudes.
Beinn Dearg Highlands and Islands
Beinn Dearg is representative of flush communities found at high altitude in the north-west Highlands. Although the extent of the communities present is restricted, they are the most diverse and best-developed alpine pioneer formations in this part of Scotland. M12 Carex saxatilis mire is frequent, with Scottish asphodel Tofieldia pusilla, two-flowered rush Juncus biglumis, three-flowered rush J. triglumis and chestnut rush J. castaneus. Open, stony flushes of M11 Carex demissa – Saxifraga aizoides mire are also well-represented.
Ben Alder and Aonach Beag Highlands and Islands
Ben Alder and Aonach Beag is representative of high altitude flushes in the central Highlands. Both open flushes of M11 Carex demissa – Saxifraga aizoides mire and more closed flushes of M12 Carex saxatilis mire are well-represented. The flushes are well-developed but localised and are notable for the occurrence of the rare scorched alpine-sedge Carex atrofusca, which is known to occur in only two other locations in the SAC series. Other characteristic species include three-flowered rush Juncus triglumis, Scottish asphodel Tofieldia pusilla, sheathed sedge Carex vaginata, alpine bistort Persicaria vivipara and the moss Blindia acuta. Other uncommon species include hair sedge Carex capillaris and alpine cat’s-tail Phleum alpinum.
Ben Heasgarnich Eastern Scotland, Highlands and Islands
Ben Heasgarnich is one of three sites in the Breadalbane range in the southern Scottish Highlands representing the range of variation of alpine pioneer formations up to high altitude. High-altitude mires are frequent on the site and include both open types of M11 Carex demissa – Saxifraga aizoides mire and more closed types of M12 Carex saxatilis mire. Rarer species present include scorched alpine-sedge Carex atrofusca, false sedge Kobresia simpliciuscula, variegated horsetail Equisetum variegatum, chestnut rush Juncus castaneus and two-flowered rush J. biglumis.
Ben Lawers Eastern Scotland
Ben Lawers is one of three sites in the Breadalbane range in the southern Scottish Highlands representing the range of variation of alpine pioneer formations up to high altitude. Ben Lawers is considered to be the most important site for this habitat type in the UK because the extent and diversity of high altitude mires present here is greater than on any other site in the UK. M12 Carex saxatilis mires are especially frequent, with more open, stony M11 Carex demissa – Saxifraga aizoides mires also common. The site supports the most abundant populations in Scotland of the rarer but characteristic species of the habitat type. These include two-flowered rush Juncus biglumis, bristle sedge Carex microglochin and scorched alpine-sedge C. atrofusca. Chestnut rush Juncus castaneus and hair sedge Carex capillaris are also frequent.
Ben Lui Eastern Scotland, Highlands and Islands
Ben Lui is one of three sites in the Breadalbane range in the southern Scottish Highlands representing the range of variation of alpine pioneer formations up to high altitude. High-altitude mires are frequent on the site and include both open types with M11 Carex demissa– Saxifraga aizoides mire and more closed types with M12 Carex saxatilis mire. The rare false sedge Kobresia simpliciuscula, Scottish asphodel Tofieldia pusilla, chestnut rush Juncus castaneus and two-flowered rush Juncus biglumis are present. The rare flush bryophytes Catoscopium nigritum, Meesia uliginosa, Timmia norvegica, Harpanthus flotovianus and Tritomaria polita are well-represented.
Caenlochan Eastern Scotland, North Eastern Scotland
Caenlochan is one of two sites in the eastern Highlands representing base-rich mires at moderately high to high altitude. These mires are frequent within the site and have high species diversity. There is a well-developed community structure and the rarer species occur frequently. Open flushes of M11 Carex demissa – Saxifraga aizoides mire and the closed M10 Carex dioica – Pinguicula vulgaris mire are both widely-developed. Characteristic species include three-flowered rush Juncus triglumis, chestnut rush J. castaneus, alpine rush J. alpinoarticulatus, Scottish asphodel Tofieldia pusilla, and sheathed sedge Carex vaginata. Hair sedge C. capillaris, alpine bistort Persicaria vivipara and alpine meadow-rue Thalictrum alpinum are also present. An additional interest is the presence of an eastern outlier of the mainly western M12 Carex saxatilis mire.
Cairngorms Highlands and Islands, North Eastern Scotland
The Cairngorms is one of two sites in the eastern Scottish Highlands representing alpine pioneer formations of lime and/or base-rich mires at moderately high altitude. Due to the predominance of acidic rocks within the Cairngorms complex this habitat is very restricted in extent, occurring mainly in the Inchrory area, associated with calcareous rocks and occurring alongside 7220 petrifying springs and 7230 alkaline fen. A small representation is also present in Glen Feshie. Despite this restricted distribution, these flushes are well-developed. They contain a range of characteristic species, including yellow saxifrage Saxifraga aizoides, Scottish asphodel Tofieldia pusilla, three-flowered rush Juncus triglumis and alpine rush J. alpinoarticulatus. Sheathed sedge Carex vaginata is also present. The main NVC type present is M11 Carex demissa – Saxifraga aizoides mire.
Moor House - Upper Teesdale Cumbria, Tees Valley and Durham
This site in northern England is the largest and most diverse example of Alpine pioneer formations of the Caricion bicoloris-atrofuscae south of the Highlands. It is a southern outlier with an extensive area of the habitat type, and is a southern outpost for many of the rarer arctic-alpine plants characteristic of this habitat type, with a unique relict mountain flora. Teesdale sandwort Minuartia stricta is restricted to Upper Teesdale, and other rare species found in this habitat type include false sedge Kobresia simpliciuscula, hair sedge Carex capillaris and Scottish asphodel Tofieldia pusilla. The NVC types represented are M10 Carex dioica – Pinguicula vulgaris mire and M11 Carex demissa – Saxifraga aizoides mire.
Morrone Birkwood North Eastern Scotland
Morrone Birkwood supports a relatively low altitude representation of this habitat in the eastern Scottish Highlands. Although they are not extensive, open flushes of M11 Carex demissa – Saxifraga aizoides mire are frequent, associated with 7220 petrifying springs and more extensive areas of 7230 Alkaline fens. Species such as yellow saxifrage Saxifraga aizoides, Scottish asphodel Tofieldia pusilla and alpine rush Juncus alpinoarticulatus are present.

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 Nevis Highlands and Islands
Eryri/ Snowdonia West Wales and The Valleys
Glen Coe Highlands and Islands
Trotternish Ridge Highlands and Islands
 

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