|IPA Factsheet - Rum|
Site Description Rum is one of the Small Isles, a group of Inner Hebridean Islands lying just off the Lochaber coast, 25 km west of Mallaig. It is a small mountainous island of national and international importance noted for its geology, upland and coastal habitats, and bird populations. The coastline of the island is mainly rocky with high cliffs to the southwest. The interior of the island comprises mountains (rising to 812m) and moorlands with burns and lochs. The long occupation of the island by people and use of the land for grazing and burning have resulted in an almost treeless landscape except for plantations and fragments of natural woodland in gorges.The upland assemblage on Rum comprises a wide range of predominantly habitats which are of international significance: wet, dry and montane heaths, species-rich and montane grasslands, both acidic and base-rich screes, blanket bog, cliffs, flushes, springs and nutrient-poor freshwater lochs and lochans are all present.
Botanical Significance Associated with the montane, sub-montane and coastal habitats is a wide variety of rare vascular and lower plants. The upland and montane flora of the ultrabasic rock habitats is especially rich. Components of the vascular plant assemblage include Arctic sandwort Arenaria norvegica, brown beak-sedge Rhynchospora fusca and pyramidal bugle Ajuga pyramidalis. Rum is one of the best sites in the UK for open rocky Calaminarian vegetation characterised by the presence of arctic sandwort Arenaria norvegica ssp. norvegica and northern rock-cress Arabis petraea, similar to that on Keen of Hamar. The habitat, which represents Calaminarian grasslands of the Violetalia calaminariae, is developed on rocky areas of debris and erosion terraces on the peridotite of Ruinsival eastwards towards Sgurr nan Gillean. A. norvegica is the rare ultramafic (ultrabasic igneous rock) species represented, while other uncommon basiphiles include purple saxifrage Saxifraga oppositifolia, mossy cyphel Minuartia sedoides and moss campion Silene acaulis. This is one of the most maritime-influenced sites of the series and the maritime species sea campion Silene uniflora, sea plantain Plantago maritima and thrift Armeria maritima are especially frequent. The Agrostis-Festuca grasslands are more scattered and more varied ecologically than on the basalt sites elsewhere in Scotland. 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. The species-rich Nardus grasslands found on Rum are 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 Festuca ovina – Agrostis capillaries – Thymus praecox grassland and Festuca ovina – Agrostis capillaris – Alchemilla 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 and open communities on ultra-basic rocks. Rum has examples of European dry heaths typical of the Inner Hebrides but is particularly noted for the presence of species-rich heath on base-rich soils. A large extent of the local, species-rich form of Calluna vulgaris – Erica cinerea heath, Thymus praecox – Carex pulicaris sub-community, occurs on steep, southerly-facing slopes on ultra-basic rocks. The associated flora includes a number of northern and arctic-alpine species, such as mountain everlasting Antennaria dioica, viviparous sheep’s-fescue Festuca vivipara, alpine meadow-rue Thalictrum alpinum, alpine bistort Persicaria vivipara and alpine saw-wort Saussurea alpina. The associated invertebrate fauna contains large populations of rare and local burnet moths. This northern form of species-rich heath complements that on Great Orme’s Head in Wales, which has a species-rich heath of a much more southern floristic character, overlying limestone. Other kinds of dry heath on Rum are typical of north-west Scotland. They include species-poor Calluna – Erica heath and Calluna – Vaccinium – Sphagnum heath, including some of the Atlantic bryophyte-rich forms of the latter. Rum has an extensive development of the black bog-rush Schoenus nigricans-rich form of northern Atlantic wet heaths that is restricted to western Scotland. It is extensive on slopes which are underlain by ultra-basic rocks, and shows the development of Schoenus in response to mild base-rich flushing. The Schoenus-rich form has affinities to the strongly-flushed Carex panicea sub-community of Scirpus cespitosus – Erica tetralix wet heath, and shows some similarities to the Schoenus-rich heaths of the Lizard district, which are also on ultra-basic rocks. Other more typical western forms of wet heath with abundant deergrass Trichophorum cespitosum and purple moor-grass Molinia caerulea are also represented. The presence of black bog-rush with other fen species occurring in extensive sheets running down-slope is peculiar to Rum. The mountainous terrain of the island of Rum off the west coast of Scotland supports waterbodies typical of oligotrophic to mesotrophic standing waters. The lochs in this site can be extremely oligotrophic with a low species diversity. However, some coastal lochs exhibit a strong maritime influence and, as a consequence, support a greater diversity and abundance of macrophytes. The three major rock types on the island, Torridonian sandstone and ultrabasic and granitic igneous rocks, influence the trophic status of the lochs. The site contains several species of note including awlwort Subularia aquatica, floating bur-reed Sparganium angustifolium and common reed Phragmites australis. The remote location of the island and its National Nature Reserve status means that the lochs have not been subject to significant unnatural change. Rum is representative of mildly calcareous and calcshist screes up to moderately high altitude in oceanic western Scotland. Rum has screes of various types, some of which are relatively small areas composed of ultra-basic rocks. Gravelly screes are widespread and unusual in supporting Scottish asphodel Tofieldia pusilla, which is usually associated with fens. Associated species include mountain everlasting Antennaria dioica, moss campion Silene acaulis, mossy cyphel Minuartia sedoides, thrift Armeria maritima, sea plantain Plantago maritima and purple saxifrage Saxifraga oppositifolia. Other species found in scree of larger rock fragments include northern rock-cress Arabis petraea, alpine penny-cress Thlaspi caerulescens, mountain sorrel Oxyria digyna and stone bramble Rubus saxatilis. Many ferns such as hay-scented buckler-fern Dryopteris aemula, northern buckler-fern D. expansa and male-fern D. filix-mas find a refuge from grazing animals in scree. Also there is a rich community of lower plants. The bryophyte assemblage on Rum includes notable species such as Acrobolbus wilsonii, Bryum dixonii, Fossombronia fimbriata, and Sphagnum skyense. One of the most important bryophyte communities, which is widespread but patchy on the more montane parts of the island, is the assemblage of oceanic-montane liverworts that occurs in association with dwarf shrub heath on steep and rocky slopes. Common species include western earwort Scapania gracilis, Taylor’s flapwort Leptoschyphus taylorii and purple spoonwort Pleurosia purpurea, but within this, on the best sites, occur uncommon species like Hutchins juniper prongwort Herbertus aduncus ssp. Hutchinsiae, Wood’s whipwort Mastigophora woodsii, arch-leaved whipwort Bazzania pearsonii and Carrington's featherwort Plagiochila carringtonii. All of these species are rare in Europe and the community is of international importance. Rum has been identified as a hotspot for Euphrasia. In particular Euphrasia heslop-harrisonii (an eyebright) has been identified on Rum; east of Kinloch pier, Camas Pliasgaig and below the NE cliff of Fionchra. This species is endemic, nationally rare and a priority species in the UK Biodiversity Action Plan (BAP).
General Habitat Description Rum has an extensive rocky coastline with cliffs rising to 210 m in the southwest. There are a few exposed beaches and a more sheltered shingle and boulder beach with intertidal mudflats in the inlet of Loch Scresort. The interior consists almost entirely of mountain and moorland with numerous streams and small lochs. Vestigial saltmarsh is restricted to small areas on gravely silt deposits and there is a small sand-dune system backed by machair grading into alluvial marsh on the flood plain of the Kilmory River. The island is largely treeless with fragments of natural woodland and scrub only in a few rocky gullies, though there are additional areas of planted woodland. There are seven significant geological areas on Rum six of which are Tertiary Igneous containing lavas, ultra basic rocks and the full suite of acid igneous rocks, together with associated faults, tuffs and tertiary sediments. The seventh area, representing the Quaternary period, is found in the Western Hills of Rum. Rum has been inhabited on a small scale for many centuries Natural woodland and scrub, thought to have been fairly widespread around 7000 BP, declined over subsequent millennia through human activity and climatic change, leaving only a few scattered remnants by the time of the Clearances. Following the Clearances sheep were introduced to Rum on a large scale and red deer were re-established following their earlier extinction. Rum was managed as a stalking estate until the 1950s. During this period burning for game management and grazing was apparently frequent and widespread. Policy woodlands were also established, principally at Kinloch. Since 1957 Rum has been in public ownership and managed as a National Nature Reserve (NNR) by SNH and its predecessor bodies. Deer management on the NNR has varied in relation to the needs of research and woodland establishment. Large exclosures to the north and later the south of Kinloch Glen have been erected to promote the establishment of woodland, with small plots elsewhere. There has been no cull in the Kilmory area since 1972 as part of continuing research into red deer behaviour and ecology. Sheep grazing on Rum ceased in 1957 but Highland cattle are used by SNH at Harris to manage the species diversity of grasslands. A population of feral goats remains, restricted largely to the west coast.
Conservation Issues Principal factors affecting the condition of the habitats in unfavourable condition are grazing and trampling. Some grazing is necessary to maintain floristic diversity, by impacting on more vigorous species such as purple moor grass or dense heather. The species-rich Nardus grassland can tolerate higher grazing pressure than the wet and dry heaths and blanket bog, but overgrazing may prevent flowering of herbs and reduce the cover of indicator species, as well as cause loss of the structural diversity required by many invertebrates typical of these habitats. An imbalance in grazing pressure may result in a change in the extent of one or more of the habitats. A habitat survey in 2008 indicated that the unfavourable habitats are recovering. There are still localised areas where herbivore impacts are too high, and more targeted management in these areas is necessary. However, grazing over the site as a whole should not be decreased further to avoid undergrazing the species-rich Nardus grassland. Human trampling on the summit ridges may have a localised negative impact on montane heaths, which recover only very slowly. Such damage should be monitored and remedial action taken if necessary. Re-generation of non-native species such as conifers and rhododendrons needs to be controlled. Maintenance of the important bird populations, visibility and access to the features of geological and geomorphological interest, and the important historical and archaeological features all need to be considered in managemnt of the IPA.