Croagh and Garvary River 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 account for about 10% of the land cover, almost all in coniferous forest in the east of the LCA
- grassland covers about 50% of the LCA, low in comparison with Northern Ireland as a whole (c.71%); the proportion in improved pastures is also low at about a tenth of the grassland
- extensive lowland blanket bog; the Pettigoe Plateau is the only extensive area of lowland western blanket bog in Northern Ireland
- examples of rare lake types
Woodlands
Woodlands account for about 10% of the land cover, almost all in coniferous forest in the east of the LCA. These are dominated by Sitka spruce with lodgepole pine and some Norway spruce and are generally of low biodiversity. There are some pockets of broadleaves that have been taken into the forests, but Garvary Wood is the only significant broadleaved woodland. This is characterized by oak with ash, birch and willows (upland oakwood) and was present in the 1830s; this gives it a 'long-established' status (such woods may have species not found in more recent woods). However, the presence of beech indicates at least modification or landscaping. The herb layer is of poor diversity but mosses and lichens are abundant.
Grassland and Arable
Grassland covers about 50% of the LCA, low in comparison with Northern Ireland as a whole (c.71%); the proportion in improved pastures is also low at about a tenth of the grassland. These pastures occur as pockets, usually associated with only one or two farms, and surrounded by acid grasslands and cut-over bog. Improved pastures are generally of low biodiversity; they are either of sown pastures with species limited to ryegrass mixtures, or are of low biodiversity as a result of constant grazing, cutting, or application of fertilizers, slurry and herbicides. Some pastures are managed more traditionally with lower grazing levels and/or cut for hay and are of greater diversity.
Acid grasslands of former pasture fields are generally species poor and dominated by rushes, but there are patches of greater diversity either on drier sites or where there is a flush of more mineral rich waters. The acid grassland also merges into cut-over blanket peat where purple moor grass often dominates.
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 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.
Blanket bog varies between that developed in the uplands of the east of Ireland, and the more oceanic, lowland blanket bog of the west. Extending from County Fermanagh in Northern Ireland into County Donegal in the Republic of Ireland, the Pettigoe Plateau is the only extensive area of lowland western blanket bog in Northern Ireland, hence the designations applied - Pettigoe Plateau ASSI, Pettigoe Plateau SAC and Pettigoe Plateau Ramsar site. The site contains a large number of well-developed pool complexes, frequent acid flushes and basin mires. The vegetation is a mixture of generally Sphagnum-rich mire with cross-leaved heath, and Sphagnum papillosum with extensive areas in which deer grass and hare's-tail cotton sedge are dominant. A notable floristic feature is the abundance of purple moor-grass and black bog-rush on the bog plain (that is away from the wettest areas with pool complexes), a characteristic feature of oceanic lowland blanket bogs. The rare bog-mosses S. fuscum, S. imbricatum and S. pulchrum occur on the site. The intermediate bladderwort and oblong-leaved sundew are abundant here but generally absent from other blanket bogs in Northern Ireland.
The Pettigoe Plateau regularly supports nationally important numbers of breeding golden plover and occasionally supports nationally important numbers of wintering Greenland white-fronted goose. There is also an important assemblage of breeding birds including hen harrier, merlin, dunlin and common tern. Other breeding species include lapwing, curlew and snipe.
The edge of the Pettigoe Plateau and alongside roads which cross it, has cut-over peatland in which there has been modern mechanical extraction.
Wetlands and Lakes
Small lakes are scattered through the peatland plateau. These are extremely oligotrophic, that is very nutrient poor, and as a result the flora and fauna are poor. For example, Tullywannia Lough (Tullywania NNR) is a small oligiotrophic lake, consisting of stands of white water-lily, and floating bur-reed and a margin of bulbous rush. The majority of lakes surveyed by the Northern Ireland Lake Survey in this LCA are of the Nymphaea-Nuphar type that is of low nutrient content but with the most diverse macrophyte communities of upland lakes. There are however three lakes which are mesotrophic. Theses include Meenatully Lough and Lough A Waddy, which are both of the Isoetes-Lobelia type and contains both type-species and are relatively rare in Northern Ireland. Lough A Waddy has associated reedbed communities present. Fens are rare, restricted to parts of lough shores as at Lough Nafeola.
The Crassowen River, a tributary of the Garvary, has the white-clawed crayfish, as does Lough Rushen. The Garvary River has not been designated under the Freshwater Fish Directive but it has excellent water quality and it is a very important nursery stream with high densities of juvenile trout and salmon.
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 cover of native woodland
Actions:
- encourage control of grazing in remaining broadleaved woodlands to foster regeneration and if necessary, encourage replanting of canopy species
- encourage planting of broadleaved woodlands through appropriate grant schemes, especially on mineral soils to the south of the LCA
GRASSLAND AND ARABLE
Issue: varied biodiversity of farmland, some improved pastures of low biodiversity, large areas of acid grassland of low biodiversity, but some flush areas and some traditionally managed grass fields of greater diversity
Actions:
- maintain and improve field boundaries especially hedgerows in areas of improved pastures . 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 and protect unsown areas and traditionally managed more species-rich grassland - to the benefit of flora and fauna, including wetland birds
HEATH AND BOGS
Issue: blanket bog of national and international importance
Actions:
- maintain the integrity of existing bogs by for example, preventing infilling, fly-tipping, fires, new drainage and new peat cutting
- prevent new forest planting on blanket bog
- promote cross-border co-operation - the Pettigoe Plateau Atlantic blanket bog continues across the border and needs to be seen as a unit.
WETLANDS
Issue: important oligotrophic and mesotrophic lakes and rivers with Priority Species and
important for trout 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
- monitor effects of peat cutting and forestry on pH, nutrient concentration and sediment load and deposition
