Lough Bradan Biodiversity Profile

 

In the following account it should be noted that for consistency, the biodiversity section follows a standard order for all LCAs even though some of the communities discussed later may have more importance for biodiversity than those discussed earlier.

Key Characteristics Woodlands

Woodlands account for less than 3% of the land cover, about half of the percentage for Northern Ireland as a whole (5.6%). Coniferous forest accounts for most of the woodland; with the exception of the south-central Glendurragh valley, large expanses occur throughout the LCA and particularly on the high ground north of Lough Bradan. These forests are dominated by Sitka spruce with smaller extents of Norway spruce, lodgepole pine and Japanese larch. Compartments of broadleaves are small and rare. In the north, the coniferous forests have been planted on blanket peat and humic gleys, but in the west although some occurs on peat, most is on gleyed soils formerly in poor pasture fields. Generally, these coniferous forests are of low biodiversity, probably lower than that of the land cover they have replaced. A possible exception is Aghaleague Wood. Today this is under Sitka spruce but the woodland was present in 1834 and it has been selected as a site for restoration of upland oakwood under the PAWS (Plantations on Ancient Woodland Sites) initiative of the Forest Service.

Broadleaved woodland is restricted to small hillside patches, streamsides and glens, and colonization of cut-over bog. On the hillsides, the woodland and scrub patches are frequently of hazel forming almost pure canopies in some locations, but in others with ash, birch and willow. Meencarragh Wood, is a large (c.19ha) woodland block extending over two small glens and the higher hillside around. The glens are covered by hazel with a mature canopy of oak and beech on the western side of the Drumgallar Burn Valley. The eastern side of this glen and the higher ground beyond is planted with conifers. The western half of the wood consists of birch scrub over cut-over peat while the central portion is formed of hazel and birch. The herb and ground layers are generally species poor and dominated by a few species of moss, but along the sides and bottoms of the glens they are more diverse and typical of western acid woodlands.

Upland mixed ashwoods are also found on hillsides, often with alder and willow in wetter parts, but they are best developed in sheltered valleys. Generally, other tree species include alder and willow, but in some locations there are beech, elm and sycamore which, together with their site, suggests that they have at least been modified / 'landscaped'; - an example is at Mullaghmore Bridge.

picture of Edenaclough WoodEdenaclogh Wood is located on the southern half of a low drumlin. The composition of the mature woodland canopy depends on local soil factors. Under drier, acidic conditions the canopy is dominated by sessile oak (upland oakwood); ash and alder are dominant under wet, neutral to base-rich conditions. The shrub layer is mixed and variable but is predominantly formed from hazel with holly locally prominent and hawthorn and regenerating canopy species occasional. Herbs and bryophytes are moderately diverse; some species have a scattered occurrence throughout the wood, such as sterile strawberry, primrose and dog violet, while the common tamarisk moss and big shaggy moss form an extensive cover through the wood. Under neutral wet conditions - lesser celandine, herb robert, wood sedge and remote sedge are common, whereas under acidic drier conditions species include wood sorrel, bluebell, ivy, tufted hair grass, greater stitchwort, hairy wood-rush and the moss bank haircap (Polytrichum formosum).

Wet woodland is largely confined to small patches within other woodland types, as in the examples above, or to inter-drumlin hollows where willow and alder are common with birch on slightly drier sites. In some inter-drumlin locations the wet woodland forms a fringe around cut-over bog which may be colonized by almost pure birch scrub or woodland.

Grassland and Arable

Improved grasslands are confined to the southern third of the LCA, but much of the western lowland is an intricate mix of more- and less-improved pastures; here the soils, derived from calp till, are very wet and heavy and unless quite intensively managed and drained give rise to high rush content. The plant species found in these wet grasslands and their diversity depend on the acidity/neutrality of the soils as well as on the level of management and the extent to which rushes have become dominant. However, because many of the fields are traditionally managed for grazing of beef cattle and sheep they can be quite diverse; common species include sweet vernal grass, common bent, crested dog's tail, meadow fescue and soft rush or jointed rush. Many of the fields qualify as the Priority Habitat lowland meadows, a habitat that is relatively scarce in the UK and even in Northern Ireland has been declining. The occurrence of this habitat in this and other western LCAs is significant both locally and nationally. Other less-managed grass fields tend towards acid grassland types that are not regarded as priorities. All of the wet grasslands provide habitats for breeding waders - breeding lapwing, snipe and curlew have all been recorded from wet grasslands in the lowlands of the LCA.

picture of Devils bit scabious flowerIn the upland margins below the blanket peat, acid grassland is often dominated by purple moor-grass and is of low biodiversity, but because of the marginal position with streams and soakaways, and because of the past history of peat cutting there can be diversity of both habitats and species. Islands of deeper, drier peat left by cutting may be heather dominated; flushes or soakaways may have sweet gale, sharp flowered rush, tormentil and carnation sedge with the purple moor-grass; and lower down the hillside there can be short-grazed and sedge-rich swards dominated by carnation sedge, tawny sedge, glaucous sedge and devil's bit scabious, whereas other fields may be almost entirely rush dominated.

Improved pastures generally have low biodiversity as a result of relatively intensive management. Some of the pastures are sown grasslands dominated by ryegrass and few other species - low biodiversity is in-built. Other grasslands have been converted to improved pastures through management. High levels of grazing or repeated cutting for silage, high inputs of fertilizers and slurry, and selective herbicides serve to reduce diversity of both flora and fauna.

Biodiversity in areas of improved pastures and arable is often concentrated in hedgerows. Indeed, they may be the most significant wildlife habitat over much of lowland Northern Ireland, especially where there are few semi-natural habitats. Hedgerows are a refuge for many woodland and farmland plants and animals. In this LCA predominantly hawthorn hedgerows are generally well-managed in the areas of intensively managed improved pastures (although some removal has taken place), but elsewhere hedges are neglected, have become overgrown and gappy and in some parts are invading the abandoned fields.

The inter-mix of habitats within the farmland, including damp grasslands, improved pastures, hedges and woods, has provided opportunities for many of the bird Priority species - bullfinch, skylark, song thrush and spotted flycatcher have been recorded.

Heaths and Bogs

Blanket bog is confined in Europe to the northwest margins of the continent, so that Northern Ireland contains not only a large proportion of the UK's and of Ireland's total area of blanket bog, but also is of major importance at a European scale. Blanket bog, and particularly intact blanket bog, in any LCA is therefore of national and international significance. It is home to plant species adapted to the water-logged, acidic, low nutrient conditions - including common heather, cross-leaved heath, cotton sedges, bog asphodel, deer sedge, bog mosses (Sphagnum species) and sundews. It is also important for over-wintering birds and for breeding birds, including waders. Blanket peat is also important as a store for carbon and as a repository of information on past environments.

Although forestry occupies much of the former blanket bog in this LCA, there are still extensive tracts remaining. Until the 1980s there were large areas of intact bog, surrounded by vast expanses of cut-over bog, but the widespread adoption of mechanized cutting, principally by the compact harvester, has left almost all of these areas damaged. The reduction in peat extraction in recent years has led to some recovery of the vegetation, but the species composition is different because some of the species, especially the bog mosses, are slow to recover; cotton sedges and deer sedge tend to dominate on former mechanized extraction sites.

An indication of the micro-habitats, structural features and species which were once more widespread in the intact areas, is evident at Meenadoan NNR. Although small, this raised bog has not been disturbed by cutting, drainage or burning. From analysis of pollen preserved in the bog, it is known know that Meenadoan developed from a small lake that existed at the end of the last ice age around 13,000 years ago. As such the site has one of the longest continuous records in Northern Ireland of vegetation development. The surface of the bog is still actively growing. Sphagnum mosses are the main vegetation, some species forming hummocks (including the relatively rare Sphagnum imbricatum and Sphagnum fuscum) whereas others thrive in pools of water; the central area of the bog has a well-developed pool-hummock complex.

In the north of the LCA, the steeper slopes of Bin and Bolaght Mountains have peat erosion, both of the gullied type and, on the summit, hagging. Also, on the northern slopes, on thinner peat, upland heathland has developed dominated by common heather.

In addition to waders and the skylark, the blanket peat also supports other Priority Species - red grouse and the golden plover.

Lowland raised bog has been almost entirely cut-over or cut-out. Black Bog FNR at Ederny, has one of the few remaining patches of intact bog. It has an excellent bog flora and includes a pool and hummock complex. Butterflies are plentiful, in particular marsh fritillary and green hairstreak.

Wetlands and Lakes

The Northern Ireland Lake Survey identified five mesotrophic lakes; that is, characterised by having a middle level of nutrients between nutrient poor (oligotrophic) and nutrient rich (eutrophic). Mesotrophic lakes potentially have the highest macrophyte diversity of any lake type. Furthermore, relative to other lake types, they contain a higher proportion of nationally scarce and rare aquatic plants. This is an increasingly rare type of lake in Northern Ireland because the nutrient status of many is being increased through input of water from agricultural land that has had applications of fertilizers and slurry. Of the five identified, Lough Lee and Lough Lack were classed as 'Isoetes-Lobelia' type on base-poor, sandy/gravely sediments with clear water and un-enriched; they contain both type species, which is rare in Northern Ireland. The other three mesotrphic lakes were not of any priority although one of the lakes at Meenacloy has a fringe of fen. Most of the other lakes in the LCA are within the uplands and surrounded by peatland; they are nutrient poor but can contain, for upland lakes, quite a diverse macrophyte flora, as at lough corr which also has a fen fringe.

picture of a white clawed crayfishLarge fens are rare in the LCA and the small patches are confined to lake fringes or to inter-drumlin hollows, sometimes where the acidic peat has been removed by cutting.

The white-clawed crayfish is recorded from several of the rivers including the Kesh and the Glendurragh.

Key Issues

General actions for UK and NI Priority Habitats and Priority Species are detailed in the Habitat Action Plans and Species Action Plans.

WOODLANDS

Issue: low broadleaved woodland cover of variable biodiversity value

Actions:

GRASSLAND AND ARABLE

Issue: varied biodiversity of farmland

Actions:

HEATH AND BOGS

Issue: prevent loss of upland heathland and decline in its biodiversity

Actions:

Issue: blanket bogs are of national and international importance

Actions:

WETLANDS

Issue: important mesotrophic and oligotrophic lakes and rivers with Priority Species

Actions:

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