South Sperrin 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
- divided into an eastern half dominated by peatlands and upland grasslands and a western half predominantly of improved pastures
- significant broadleaved woodland mainly in the western half and generally confined to steep slopes along incised streams and rivers
- has some of the largest upland broadleaved woodlands in Northern Ireland
- extensive areas of State and Private Forestry in the east
- little intact blanket peat remaining, most has been cut-over, drained or is eroded.
- Owenkillew River and its immediate environs of national and international importance
Woodlands
Woodlands occupy about 7% of the LCA; the majority of this is coniferous forest, principally private forestry in Glenlark. This was planted mainly on gullied and thin peat, although on the upper slopes on the northern side of the valley intact blanket bog was included. Forestry continues to the north of the col at Sawelabeg and most of Goles Forest, on the northern slopes between Carnanelly Mt. and Sleiveavaddy Mt., is included in the LCA. Elsewhere, small private conifer plantations are scattered on the hillsides. Sitka spruce and lodgepole pine dominate the conifer plantations. These forests are generally of poor biodiversity although red squirrel has been recorded in Goles and Sawelabeg forests.
The loss of intact blanket bog to forestry is regrettable, however, it should be noted that Forest Service policy now has a presumption against new planting of ombrogenous (bogs produced by rainfall) bog. The Owenkillew also has the largest known population in Northern Ireland of the freshwater pearl mussel.
Although a minority of the woodland area, broadleaved woodlands in the LCA include some of the most important in Northern Ireland. Most are located in the western half of the LCA and generally are along the Owenkillew River and its major tributaries or alongside the many small streams flowing down the steep slopes of the major river valleys. Several of these streamside woods are Upland oakwood: oak is usually accompanied by hazel and birch is frequent. In wetter parts of these woods, alder and willow may be the most abundant tree species. A typical example is Crockaghole Wood ASSI - one of the few woodlands in the eastern half of the LCA. Where grazing is limited, the ground flora is diverse, especially with the presence of wetter, flushed areas. Mosses and lichens, including those growing on the trees, are abundant. In addition to these streamside oakwoods, there is the Drumlea and Mullan Woods ASSI, one of the largest areas of acid oakwood in Northern Ireland. The understorey varies with soil wetness and base status, as does the rich ground flora, which contains species that may be indicative of an ancient woodland site. Boorin Wood, part of which is in the Boorin NNR, is also an acid oak woodland although there is an area of old willow carr as well as an area planted with beech.
Upland mixed ashwood is rare in this LCA; the main site is near Golan Bridge where the ground flora is diverse. Hazel woodlands are common streamside woods and also occur on old meander scars in the Owenkillew valley; birch and oak are common, with alder and willow in wetter parts. In the extreme west, the LCA clips the upper portion of the Owenkillew and Glenelly Woods ASSI; in this part, the wood is almost entirely of birch.
Beltrim Castle is the only area of Lowland woodland pasture and parkland; mixed woodlands are extensive around the borders of the estate. These have a wide range of species including larch, beech, sycamore, Scots pine, oak and elm. Such mixed planting is common around Gortin and indeed occasional conifers have been planted in several streamside and riverside locations in the LCA as part of nineteenth century 'landscaping'.
Broadleaved and mixed woodlands occupy only a small percentage of the area of the LCA, but nevertheless some of the largest and best examples of upland woodland types in Northern Ireland are found here. For the most part, steep slopes have protected the woodlands from clearance and from heavy grazing, but some of the larger examples are more accessible. In consequence, parts of these woods have a poorer ground flora and there is limited re-generation of the canopy trees.
Grassland and Arable
Arable land is rare in the LCA and confined to better drained soils on lower land near Gortin. Improved pasture accounts for approximately 22% of the LCA and is almost entirely in the western half, coinciding with the lower slopes and bottoms of the Owenreagh and Owenkillew rivers. The belt of improved pastures widens at the confluence of the two rivers. Generally, these pastures are under constant grazing and have little biodiversity interest. Field boundaries in these lower pastures are predominantly of hedgerows which become fuller around Gortin. Spring flowering plants, such as the primrose and violet, are quite common in the area.
Further upslope, hedges become thin and are often replaced by stonewalls. Here the pastures and field boundaries have deteriorated and former enclosed pastures are dominated by rushes. The more nutritious grasses and herbs have been replaced by coarser grasses; there is a gradual transition into acid grassland and cut-over bog. The upper slopes therefore have a diversity of communities that should be retained; in current agricultural circumstances it is unlikely that there will be much reclamation and loss of these communities.
Heaths and Bogs
The eastern half of the LCA is dominated by uplands with a complex land cover resulting from topography and history of land use. For example, on some slopes there is little or no peat because the slopes are too steep for peat to form or because the peat has been removed by generations of cutting for fuel. The steep slopes have also led to erosion of the peat, generally by gullies, but on the highest summits there is some hagging. Vast areas of the blanket peat have also been drained, some for forestry (see above), but much of it to encourage heather growth and improve the grazing. Yet other areas have been reclaimed for enclosed pastures; many older examples have reverted to rushes but more recent reclamation is evident.
As a result of these topographic and land use factors, a boundary between peatland and acid grasslands is difficult to determine, there is gradation from one to the other and an intermixing of the two. Also, intact blanket bog is confined to a few flatter summit areas and spurs: for example, to the northeast of Greenan Hill and between Mullydoo and Crockanboy Hill.
Mechanised peat extraction is concentrated in three main areas - on the western slopes of Mullaghcoula, on the southern slopes of Mullaghturk and on the eastern slopes of Mile Mountain. The latter two locations have extensive sites; both are on former cut or gullied peat.
Intact blanket peat comprises only 13% of the remaining blanket peat in Northern Ireland and is an internationally important habitat, especially on a European scale. As discussed, the LCA has little intact blanket peat; it is important for local, national and international reasons therefore that the few areas of intact blanket peat and their characteristic plant species are retained. The cut-over areas too have importance for biodiversity, particularly because there is an inter-mix of islands of uncut peat, rush dominated acid grasslands, and heather dominated drained areas. This inter-mix gives a diversity of plant species and habitats for bird and insect life including waders (curlew is recorded) and, with the presence of heather dominated areas, the red grouse.
Wetlands and Lakes
There are no significant areas of standing water in the LCA. Among the rivers, the Owenkillew River ASSI is of particular importance for the Freshwater Pearl Mussel, supporting the largest known population in Northern Ireland, and one of the few rivers to retain a significant and viable population of this rare shellfish. In addition, both salmon and brown trout are present in the river; species such as brook lamprey, otter (present in most rivers in the LCA) dipper and kingfisher also are present. The river and its immediate environs, including significant woodlands (see above), is a cSAC. Future threats from forestry include felling activities; the Glenlark River is a tributary of the Owenkillew, a salmonid river where spawning and nursery beds could be under threat from particulate pollution.
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 woodland cover of variable biodiversity value, but including important examples of Priority types.
Actions:
- enhance the biodiversity value of broadleaved woodlands by preventing further loss; by retention of fallen and veteran trees (particularly for bryophytes, ferns, fungi and fauna)
- encourage control of grazing in broadleaved woodlands to foster regeneration, so that there is neither over-grazing, thereby reducing the ground flora, or under-grazing that would allow more vigorous species to become dominant; if necessary, encourage replanting of canopy species
- encourage planting of broadleaved plantations, through appropriate grant schemes, rather than the small conifer plantations which are of poor biodiversity and landscape value; any future forestry expansion should be limited to previously cut or eroded blanket bog slopes
- further study of the history and ecology of broadleaved and mixed woodlands, particularly any ancient and long-established as a key to future management
GRASSLAND AND ARABLE
Issue: poor biodiversity of improved pastures and thinning hedges
Actions:
- encourage (through participation in Environmental Schemes) adoption of less intensive management of pastures to allow reversion to more species-rich grassland
- maintain and improve field boundaries especially hedgerows in areas of improved pasture. This may be achieved through adoption of correct cutting cycles; hedge laying and replanting where necessary; leaving saplings uncut to develop into hedgerow trees; avoidance of spraying with fertilisers, slurry, herbicides; provision of wildlife strips and conservation headlands around fields; and limitation of field amalgamation.
HEATHS AND BOGS
Issue: loss of heathland and decline in its biodiversity
Actions:
- promote membership of the Sperrins ESA or other environmental schemes through consultation with farmers and thereby
- control grazing intensity on existing heathland to encourage development of heathland and of heather of different ages
- discourage 'reclamation' to pasture fields around heathland margins
- discourage afforestation
Issue: blanket bogs are of national and international importance, however vast areas have been drained in this area
Actions:
- maintain the integrity of existing blanket bogs by for example, preventing infilling, fly-tipping, fires, new drainage and mechanised peat cutting - applies particularly to intact bogs but cut-over bogs can provide important habitats for birds and invertebrate
- sconsider restoration of bog habitats through appropriate water level management, removal of individual colonising trees and phasing out peat cutting - applies particularly to any areas of recent mechanical cutting
- prevent new forest planting on blanket bogs
WETLANDS AND LAKES
Issue: the Owenkillew River ASSI and its immediate environs are of national and international importance with populations of rare aquatic plants and fauna; important for Freshwater Pearl Mussel, salmon and brown trout.
Actions:
- protect the water quality of rivers through nutrient management and by reducing suspended sediments; prevent the release of particles released through peat cutting or forestry operations; install sediment traps at large extraction sites
- promote and encourage existing good farming practices so that rivers are not polluted by releases from silage effluent, herbicides, pesticides, fertilisers or sheep dip
- monitor streams in relation to peat cutting (sediment load and deposition) - important for salmon that nursery and spawning beds are clear
- monitor streams in relation to expansion of rural/urban housing and associated septic tanks/sewage treatment plants
- recognise that monitoring of streams in relation to forestry and other operations upstream may be important
