Clogher Valley Lowlands Biodiversity Profile

 

In the following account of this LCA 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 occupy about 4% of the LCA (Northern Ireland as a whole c. 5.6%), almost equally divided between coniferous and mixed/broadleaved
• large broadleaved and mixed woodlands are confined to past and present demesnes
• outside of the estates, many of the stream-side woodlands have either been planted or 'landscaped'
• many of these estate and stream-side woodlands were present in 1834 (first edition of 6" maps) so are at least 'long-established' and may be more diverse than more recent woodlands
• birch dominated woodland is one of the most frequent types of woodland in the LCA and many are located on cut-over lowland peat bogs
• grassland covers over 90% of the LCA (compared with 71% for Northern Ireland as a whole) and over four-fifths of this is improved pasture of low biodiversity
• wet grasslands, some with traditional management for hay, occur in inter-drumlin hollows; some are more plant species-rich; provide habitats for wetland birds
• lowland bog (Northern Ireland has a large proportion of the UK total) is widespread in this LCA, but almost all has been cut-over; one remaining intact bog
• important and rare lake types - eutrophic, mesotrophic and marl lakes - and rivers with Priority Species.

Woodlands

Woodlands occupy about 4% of the LCA (Northern Ireland as a whole c. 5.6%), almost equally divided between coniferous and mixed/broadleaved. Most of the coniferous forest is in State Forests, comprising parts of Favour Royal, Fardross, Grogey and Knockmany Forests. Although there are compartments of mixed broadleaves and conifers at Favour Royal, and some trees from the former demesne, Sitka spruce is the dominant tree species followed by Norway spruce and Japanese larch. Favour Royal also contains one of the People's Millenium Forests - an attempt, linked with Coillte, to re-establish native woodland. That part of Fardross Forest falling in this LCA is also dominated by Sitka spruce, but there is a significant amount of lodgepole pine and Norway spruce. Grogey Forest has the same three species. However, at Knockmany Forest the planting pattern is far more complex with many small compartments, some of pure conifers (including compartments of Sitka spruce and of Douglas fir) others of hardwoods and of mixed planting. There is also a small area of wet woodland in the Knockmany FNR; this is willow carr near to Ardunshin Lough.

Large broadleaved and mixed woodlands are confined to past and present demesnes (lowland woodland pasture and parkland) including Colebrooke Park - Ashbrooke, Blessingbourne and Tempo Manor. Some former demesnes have been planted with conifers (e.g. Favour Royal and Knockmany, see above) and other smaller ones have lost many of their trees and wooded areas.

Colebrooke Park has several conifer plantations, with Norway spruce, Sitka spruce, Scots pine and larch, but there are extensive broadleaved and mixed woodlands. In the planted woodlands, beech and oak dominate, but there is a wide range of other species that includes ash, sycamore, copper beech, elm and lime. The understorey is of hazel and rhododendron, but the herb layer is generally limited in its diversity; lichens and mosses are abundant. Elsewhere in the Park, birch woodland is extensive, usually on dry soils but there are sections with wet woodland in which willow and alder are found. The woodlands at Colebrooke are more extensive than in 1834, but the central parts were present and may therefore contain species not normally found in more recent woodlands. Tempo Manor has some conifer plantation, but here too beech is the characteristic species of the planted woodland and the range of species found is also similar. The herb layer is generally of low diversity but there are abundant mosses and lichens. Most of the woodland was present in 1834. In contrast, the large woodlands to the north of the lake at Blessingbourne were not present in 1834; woodland was restricted to the margins of the estate.

Outside of the estates, many of the stream-side woodlands have either been planted or 'landscaped'; for example, at Oldtown Wood the presence of beech in the oak, birch and ash canopy indicates at least modification of this wood. It was present in 1834 and has a diverse herb layer and abundant mosses and lichens. Just to the north and also along the Tempo River, Drumlone wood includes alder, ash and hazel and a diverse ground flora is present.

Birch dominated woodland is one of the most frequent types of woodland in the LCA and many are located on cut-over lowland peat bogs. Where the remaining peat is relatively dry, the woodland may be almost pure birch, as on the cut-over bogs near Ossier Hill and Screeby Hill, but in wetter parts, for example around the edge of the bogs, willow and alder may produce a wet woodland fringe.

Grassland and Arable

Grassland covers over 90% of the LCA (compared with 71% for Northern Ireland as a whole) and over four-fifths of this is improved pasture. This generally has 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. Arable land is insignificant in this LCA.

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, fields are relatively large and are bounded by hedges that are often overgrown with tall, mature trees.

Although improved pastures dominate the landscape, there are areas of damp and acid grasslands. Most frequently these occur in the inter-drumlin hollows and flat land alongside some of the rivers and some are located on former cut-over bogs. Many of the fields are dominated by rushes and are generally of low species diversity, but where the fields are derived from former cut-over bog there may be remnants of the peat vegetation. Occasional fields are still managed as hay meadows (lowland meadows) and where the management is less intensive these tend to have higher species diversity.

In the east, the southern border of the LCA includes the lower slopes of the plateau centred on Slieve Beagh. Here soils become increasingly humic and wet and indeed there is some thin peat; where these soils are not under coniferous forest, upland acid grassland of low biodiversity dominates.

Despite the dominance of improved pastures in the landscape, the intricate mix of patches of wet grassland, bog, woods, occasional arable fields and hedges has given rise to a variety of habitats that are suitable for many of the bird Priority Species - bullfinch, skylark, song thrush, spotted flycatcher, reed bunting, linnet and curlew have all been recorded from the farmland area of this LCA. In addition lapwing and snipe have been recorded from damp grasslands.

Heaths and Bogs

Blanket bog is restricted in occurrence to a narrow strip along the border of the LCA to the north of Clabby. It has all been cut-over in the past. Lowland raised bog is more extensive, particularly west of Fivemiletown, with many examples located in inter-drumlin hollows and on flatter land in the Colebrook valley. Most of the inter-drumlin bogs are small and all have been cut-over in the past; many have been colonised by birch, sometimes with a fringe of wet woodland, and some have been planted with conifers. Cut-over bog does, however, have biodiversity value, pools left by cutting provide habitats for invertebrates and, together with damp grasslands that often surround them, they are also habitats for breeding waders - lapwing, snipe and curlew have all been recorded from raised bog in this LCA.

Clabby Bog is the only example of intact bog in the LCA; it is on a broad, gently undulating area between low drumlins. There is no central dome and it has few characteristics of lowland raised bog, indeed it may be transitional towards low-level blanket bog. There are a few large, scattered hummocks, but generally the microtopography (variations in the height and roughness of the ground surface) is subdued and dominated by Sphagnum capillifolium and Sphagnum papillosum. Pools do occur, but generally they are very small. The bog contains some notable species of bog moss; the presence of white-beaked sedge is mostly as a result of burning and modern machine cutting of peat.

Examples of intact bog are particularly important; Northern Ireland has a large proportion of the lowland bog found in the UK, but following generations of cutting, less than 9% of the remaining lowland bog was classed as intact in the 1980s. Since then further loss has taken place through mechanical extraction in all parts of Northern Ireland. In this LCA, mechanized peat cutting has been widespread, mostly of the compact harvester type for fuel peat, but to the north of Colebrooke extraction has been on a much larger scale involving excavators and field-press machines.

Heath is rare in the LCA and confined to small areas where common heather dominates deeper drier areas of cut-over peat or to small patches of gorse on steep slopes.

Wetlands and Lakes

The LCA contains a number of lakes, several of which are of relatively rare types. Lough Eyes is the largest lough and has been classed mesotrophic, of the Nymphaea/Fontinalis/Littorella type, which is relatively base and nutrient poor and usually of a mid-altitudinal position. Drumcor Lough has been similarly classified. Mesotrophic lakes are characterised by having a middle level of nutrients between nutrient poor (oligotrophic) and nutrient rich (eutrophic). Potentially they 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. Ballagh Lough, Augher Lough, Fymore Lough, Lough Corban and Round Lough have all been classed as examples of eutrophic standing waters. Ballagh Lough and Augher Lough have been classed as of the type that probably has the highest diversity of aquatic macrophytes in a eutrophic water body. Fymore Lough and Lough Corban belong to a particularly rare type generally restricted to the southern Erne system, whereas round Lough belongs to a comparatively rare type with a Fermanagh- South Tyrone distribution. Marl lakes are generally restricted to limestone catchments, hence they are most common in south Fermanagh; Cullentra, Screeby, Fadda and Gunnell loughs are all marl lakes, the latter three belonging to the type that is the cleanest, clearest hard water lakes with the highest base status and most specialised flora; it is rare and vulnerable to phosphate accumulation.

The Tempo River, Colebrooke River and River Blackwater have river water crowfoot and the white-clawed crayfish is recorded from several of the rivers. The Colebrook River (along with the Ballinamallard) is currently being stocked with juvenile salmon as part of a cross-border salmon enhancement initiative for the Erne system.

Fens are not widespread and occur as small fringes to lakes, for example Lough Eyes, Clabby Lough, Augher Lough among others. Occasionally, peat cutting has been sufficient to remove most of the acid peat and the soil water is now more base-rich; in these conditions fen has developed in the inter-drumlin hollows. Fens are under threat - they have been reclaimed for agriculture, used as land-fill sites and the species assemblage has been changes as a result of nutrient enrichment from surrounding land. Nevertheless, Northern Ireland has a considerable proportion of the UK's fens, particularly in counties Down, Armagh and Fermanagh so that examples in this LCA have local and national significance for biodiversity; in addition to the diversity of plant species, fens are important habitats for other Priority Species such as the marsh fritillary butterfly.

Reedbeds occur around a limited number of lakes, including Lough Eyes and Round Lough.

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 although containing potentially

important estate woodlands

Actions:

• enhance the biodiversity value of demesne/parkland woodland through control of grazing and felling; by encouraging planting of saplings of the standard trees; by preventing further loss of parkland; by retention of fallen and veteran trees (particularly for bryophytes, ferns, fungi and fauna); by gradual replacement of conifer plantations
• further study of the history and ecology of demesne and other broadleaved woodlands particularly any ancient and long-established, as a key to future management
• encourage control of grazing in broadleaved woodlands to foster regeneration and if necessary, encourage replanting of canopy species
• encourage planting of native broadleaved plantations through appropriate grant schemes, rather than the small conifer plantations which are of poor biodiversity and landscape value
• retain birch and wet woodlands that have colonised cut-over bogs; ensure that they are not lost to drainage, land-fill

GRASSLAND AND ARABLE

Issue: poor biodiversity of farmland

Actions:

• maintain and improve field boundaries especially hedgerows . 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 of species-rich grassland, especially damp meadows and those used traditionally (e.g. for hay)
• maintain and enhance wet grassland by restricting field or arterial drainage
• leave stubble over winter, rather than autumn ploughing, to increase food resources for farmland birds; spring sown cereals are beneficial to breeding farmland birds.

HEATH AND BOGS

Issue: lowland bogs are of national and international importance, but only one significant area of intact lowland bog in the LCA

Actions:

• maintain the integrity of existing lowland raised bogs by for example, preventing infilling, fly-tipping, fires, new drainage and new peat cutting - this applies to cut-over bogs because they provide micro-habitats for invertebrates and habitats for wetland birds
• consider restoration of raised bog habitats through appropriate water level management, removal of individual colonizing trees and phasing out peat cutting
• prevent new forest planting on raised bog

WETLANDS

Issue: fens in Northern Ireland are a large proportion of the UK resource

Actions:

• protect fens against loss by drainage and infill, which includes use as official refuse tips as well as sites in which to deposit building rubble and fly-tipping.
• leakage of fertilizers and slurry from surrounding agricultural land should be prevented as this increases the nutrient levels and affects species composition.

Issue: important and rare lake types - eutrophic, mesotrophic and marl lakes - and rivers with Priority Species.

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 streams in relation to expansion of rural/urban housing and associated septic tanks/sewage treatment plants
• monitor effects of peat extraction - particularly important to retain clear stream beds, for example for nursery and spawning grounds of salmonid fish.

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