Camowen Valley Biodiversity Profile
In the following account of this LCA it should be noted that for consistency, the biodiversity section follows the 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 account for only around 1.5% of the land cover, low even for Northern Ireland (c.5.6%); almost all is conifer plantations; woodland is of low biodiversity in this LCA
- although improved grasslands are extensive, the level of improvement is varied and there is a complex mosaic of pasture fields with poor, wet pastures intermixed with sown ryegrass
- acid grasslands frequent - some rush dominated, but around cut-over bogs purple moor grass
- some large, internationally important lowland raised bogs
Woodlands
Woodlands account for only around 1.5% of the land cover, low even for Northern Ireland (c.5.6%); almost all is conifer plantations, including one large plantation near Mount View. Broadleaved woodland is confined to small patches of birch, willow and alder on cut-over bog, and to planting around some larger houses. There are no woodlands of importance to biodiversity, indeed there is a need for planting.
Grassland and Arable
Grassland covers around three-quarters of the LCA, of which about 70% is improved pastures (but this may be an over-estimate from the Land Cover Mapping). 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. However, in this LCA many of the pasture fields are less improved and indeed may be reverting, with the appearance of clumps of rushes; there is a continuum in many parts from improved pastures to rough and acid grassland or an intricate mosaic of small fields of varying pasture quality. Arable land (includes grass reseeding) is about 2% of the land cover.
Biodiversity in areas of improved pastures and arable is often concentrated in hedgerows, but in this LCA they are generally poor, thin lines of occasional shrubs and of little biodiversity interest.
Acid grassland is widespread and often occurs in areas of cut-over peat; where this is thin, and where the wetness is the product of heavy mineral soils, rushes often dominate the fields. Around the remaining patches of intact bog, peat may be deeper and the grassland can be dominated by purple moor grass, occasionally with flushes of more mobile water that have a higher plant species diversity.
The generally low biodiversity of the farmland is reflected in the low number of bird Priority Species - in addition to curlew only song thrush, spotted fly catcher, reed bunting and skylark have been recorded.
Heaths and Bogs
Lowland raised bog is extensive in the LCA. Lowland raised bog is a rare habitat in the UK, and Northern Ireland has a large proportion of that remaining; in particular it has much of the intact lowland bog. In the best examples there is a diversity of structural features including hummocks and hollows and pools that give rise to micro-habitats related especially to the height of the water table. The plant species are adapted not only to the generally waterlogged, acid and low nutrient conditions, but also to these small-scale variations in topography and water level. Typical plant species include bog mosses, deer sedge, cotton sedges, bog asphodel, sundews, cross-leaved heath and common heather. Lowland raised bogs are also an important repository of environmental information from the past and, together with blanket bog, a significant store of carbon.
To the east of Omagh drumlins are fewer than to the south and west and the rivers are incised into broad, low platforms on which large raised bogs have developed. Most of the bogs have been cut-over in the past, but there are areas of intact raised bog that are amongst the largest in the west of Northern Ireland. Unfortunately, these intact areas are fewer than they were even as late as the 1980s - mechanical extraction for both fuel (by compact harvester) and horticulture (by milling and vacuum extraction) has removed significant areas.
Deroran Bog ASSI is one of the largest remaining lowland raised bogs in Northern Ireland. Despite reclamation around the edges and intensive turf cutting to the south, it retains an intact surface of around 50ha. Deroran Bog displays the domed profile typical of raised bogs, but the micro-topography of the surface is generally rather subdued. There are several large hummocks and occasional small pools where Sphagnum cuspidatum is dominant. The surface of the bog is dominated by common heather, with abundant crossed-leaved heath and deer sedge. Common bog cotton and hare's tail cotton sedge are frequent throughout and bog asphodel dominates in wetter hollows. S. papillosum is the most abundant bog moss species, but the locally distributed species, S. fuscum and S. imbricatum, also occur. In addition, the purple liverwort, Pleurozia purpurea, indicative of "western" bog, is found in wetter areas.
Smaller intact lowland bogs occur just north of Deroran around Cloghfin, but machine extraction has been quite intense. The former extensive Grove Bog has largely been lost to peat milling. Rush's Hill Bog has experienced drainage in the eastern half and some mechanical extraction, as well as a number of episodes of burning, but it retains an intact core with remains of a pool system.
Despite the disturbance and the high proportion of peat that is cut-over, the raised bogs provide habitats for waders, including snipe and curlew, and the abundance of heather provides for the red grouse.
Wetlands and Lakes
The Camowen River has river water crowfoot and is also a salmon river. There are no priority lakes, fens or reedbeds of note in the LCA.
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: very low woodland cover, especially of broadleaves
Actions:
- encourage planting of native broadleaved woodlands, through appropriate grant schemes, rather than the small conifer plantations which are of poor biodiversity and landscape value.
- ensure that small patches of wet woodland are retained - not lost by drainage, land-fill or clearance.
GRASSLAND AND ARABLE
Issue: poor biodiversity of farmland
Actions:
- maintain and improve field boundaries especially hedgerows where appropriate to the tradition of the landscape. 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 fertilizers, slurry, herbicides; provision of wildlife strips and conservation headlands around fields; and limitation of field amalgamation.
- encourage (through participation in Environmental Schemes) adoption of less intensive management of pastures to allow reversion to more species-rich grassland
- promote survey of un-sown semi-natural grasslands to establish diversity
HEATH AND BOGS
Issue: raised bogs of national and international importance including some sizeable
intact bogs
Actions:
- maintain the integrity of existing lowland raised bogs by for example, preventing infilling, fly-tipping, fires, new drainage and new peat cutting
- consider restoration of raised bog habitats through appropriate water level management, removal of individual colonizing trees and phasing out peat cutting - particularly intact bog where mechanical extraction may have ceased or occupies only small parts of bogs
- prevent new forest planting on raised bog
WETLANDS
Issue: important rivers and tributaries, with Priority species and salmon
Actions:
- protect water quality of lakes and rivers through nutrient management and by reducing suspended sediments thus,
- promote and encourage existing good farming practices so that streams are not polluted by run-off from agricultural land or seepage from silage pits
- continued monitoring of streams below industrial plants and quarries
- monitor streams in relation to expansion of rural/urban housing and associated septic tanks/sewage treatment plants
- monitor streams in relation to forestry and peat cutting - pH, nutrient content, sediment load and deposition - and effects on fish and other wildlife.
