Roe Basin 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

• although woodlands cover only c.3.5% of the LCA (Northern Ireland average c. 5.6%), there are locally and nationally important examples of Priority Habitat types, in particular of western upland oakwoods
• exceptional examples of hazel woodlands on steep slopes and incised valleys
• grassland occupies over 82% of the land (Northern Ireland as a whole c.71%), which reflects the lowland character, as does the proportion (four-fifths) that is improved pasture
• small patches of damp grassland in lowlands and on upland margins important for birds, including breeding waders
• some blanket and raised bog, but although all is cut-over it adds to the diversity of plants and provides habitats for invertebrates and birds
• rivers of importance for Priority species and of international importance for Atlantic salmon

Woodlands

Woodlands cover c.3.5% of the LCA, most is broadleaved or mixed woodland with coniferous woodland largely confined to Ballykelly Forest and a small portion of Gortnamoyagh Forest. Ballykelly Forest is dominated by Sitka spruce and Douglas fir, but there are also compartments of larch and of oak. The small portion of Gortnamoyagh is of Sitka spruce and larch with some ash and mixed hardwoods.

The broadleaved woodland is of several types, including hazel or hazel/oak woodlands, upland oakwoods, wet woodlands, woodlands on cut-over bogs, and estate woodlands.

Hazel and hazel/oak woodlands are widespread in the LCA occurring on hillsides and in steep-sided valleys. One of the largest extents is in the northeast corner of the LCA on the slopes around Tircorran. This is a complex area where woodland and scrub is extending over abandoned fields, some with flushed/seepage zones. Although hazel dominates and ash is abundant, particularly alongside streams, there is diversity because of the changing ground conditions. In wetter areas willow and alder form pockets of wet woodland. The herb layer is likewise diverse and species-rich containing not only many spring-flowering plants such as primrose, bluebell, ransoms and wood anemone, but in damper areas golden saxifrage, bugle and in some of the wettest parts, yellow flag iris. Yet other parts of the wood are drier and have bracken, although most of the woodland and scrub is base-rich.

Woodland along the Altahullion Burn is predominantly hazel but there are some scattered oaks; the herb layer here is also species-rich. At Altcattan Glen hazel woodland is also dominant and the herb layer beneath is diverse. There are scattered stands of oaks where the herb layer is typical of oak woodland on acid soils and includes great woodrush and hard fern. There are patches of birch and the presence of beech suggests that the wood has been 'landscaped'. Similar hazel/oak woodlands occur alongside several other rivers, including the Castle River, Wood Burn and parts of the upper R. Roe. Some of these woodlands are on the first edition of the 6" OS maps and therefore are at least 'long-established' and in view of the species richness could be ancient. Their diversity and proximity to other valued habitats make them important to the biodiversity of this LCA.

Whereas oak is often present in streamside hazel woodlands, there are several streamsides that are dominated by upland oakwood. Pre-eminent among these is Banagher Glen ASSI (also Banagher Glen NNR and Banagher Glen SAC), which has one of the largest and least disturbed examples of sessile oak woods in Northern Ireland; however, it should be noted that sections of the wood are dominated by ash (upland mixed ashwoods), hazel or birch or indeed mixes of these species. This diversity of woodland types is the result of a complex geology so that there are both base-rich and base-poor sections. The herb layer is consequently also diverse and in many parts, species-rich. The oak is commonly associated with bilberry, great woodrush and common cow wheat, whereas under the ash and hazel, the more base-rich sections, bluebell may be dominant; there are also wet areas with golden saxifrage and bugle. Although the site may have been felled around 1770 it has clearly regenerated and has a long history of continuous woodland cover. There is low number of non-native species and a relative abundance of old trees and epiphytes that include notable mosses and lichens. The site is therefore of major importance to biodiversity not only of the LCA and Northern Ireland, but also, as an example of a western upland oakwood, it is of national importance.

The upland oakwood in Benady Glen (upper R. Roe) is less extensive, but it too is varied in tree species (including birch, hazel, ash, sycamore) and has a species-rich herb layer. There are also examples of upland oakwood mixed with birch, sycamore, willows and alder in Ballykelly Glen; the herb layer is varied in occurrence, but overall is quite species-rich.

Upland mixed ashwoods are of scattered occurrence in the LCA and often difficult to delimit because they are mixed with other woodland types, as for example in Banagher Glen and in the many examples of hazel woodlands. A further example is the Faughanvale River where ash is mixed with hazel and with oak and, as with many other sites, the variation in soils, slopes and management has led to a great diversity in the herb layer including wood rushes, common cow wheat, bluebell, wood anemone and wood sanicle.

Wet woodlands are likewise scattered through other woodland types (as at Tircorran), but they are also found around and across cut-over bogs. Where the cutting has removed most of the peat, so that conditions are less acid, willow and alder dominate. These give way to birch woodland that has often colonised where the remaining peat is deeper and ground conditions are drier (see below).

Areas of estate woodland (lowland woodland pasture and parkland) in the LCA include what is now the Roe Valley Country Park, formerly Daisy Hill. Deer Park Wood contains some semi-natural hazel/oak wood, but the majority is dominated by beech. The varied sites - beech wood, hazel/oak wood, riverside and rocky outcrops - have produced a very diverse flora. Drenagh has the most extensive estate woods, predominantly of oak with some small stands of beech. Voluntary sycamore and ash are found within the woods and there are also individual conifers, including Scots pine, Douglas fir, grand fir and noble fir. The estate and parkland date back to the 1700s so that the woodlands are at least 'long established' (sufficient time may have elapsed for species to colonise so that herb layer plants and mosses and lichens are more diverse than in recent woods). There is, however, abundant rhododendron that is gradually being removed.

Other estate woodlands include Pellipar House where they are mainly a fringe around the demesne, Ardnargle and The Rectory at Ballykelly.

Grassland and Arable

Grassland occupies over 82% of the land, a high percentage relative to Northern Ireland as a whole (c.71%), but one that reflects the lowland character, as does the proportion (four-fifths) that is improved pasture. Arable land (including grass re-seeding) accounts for about 7% of the land cover, around the Northern Ireland average.

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, dense and treed - commonly ash, oak and, near to estates, with beech. Fields are relatively large, especially on the better-drained land (frequently brown earths over sand and gravel), and there is some field amalgamation. Toward the upland edges of the LCA fields have been abandoned and hedges, where they occur, are gappy and frequently of gorse reinforced by wire.

Much of the rough grassland occurs on these upland margins where they may have clumps of rushes separated by grazed grasses, be rush dominated or may merge into more acidic areas on the margins of cut-over blanket bog where wavy hair grass, mat grass or purple moor grass may be frequent. However, there are rough grasslands in the lowlands too; they surround some areas of cut-over lowland bog, occur in field corners or comprise one or two fields in low situations. Depending on situation, these generally damp grasslands may be acidic, with species similar to the upland margins, or neutral with high or dominant rush cover and include other species such as tufted hair grass, meadow sweet and marsh marigold. Small, isolated patches of unsown dry grasslands also occur, often on the upper parts of steep streamside slopes.

These generally damp grasslands are important not only for the plant diversity, but because they provide habitats for invertebrates and breeding waders; for example breeding curlew have been recorded on the upland marginal grasslands at Aghansillagh and Cloghan and curlew and snipe have been recorded on lowland damp pastures at Lislane. They also form an important part of the farmland mosaic so that sever bird Priority Species are widespread in the LCA - including bullfinch, linnet, reed bunting, skylark, song thrush, yellowhammer and spotted flycatcher.

Heaths and Bog

Although patches of gorse are widespread, especially on abandoned land and steeper slopes, most heather heathland is associated with cut-over bogs. Both blanket bog and lowland bog are found in the LCA but there is no significant intact bog of either type. Not only is the blanket bog cut-over, but in many instances it is also treed; at Blackfalls, south of the Altahullion Burn, birch and willow scrub is colonising the common heather dominated bog surface. Trees are also colonising the blanket bog above the Leake Water.

Lowland raised bog is also cut over and whilst some bogs show signs of healing, with a good cover of bog plant species (including common heather, cotton sedges, deer sedge and bog mosses), others have been used as refuse tips (Drumaduff). Small areas of bare peat indicate modern machine (compact harvester) extraction. There is also tree colonisation extending from the edges of bogs (willow and birch) as at Flanders.

Wetlands and Lakes

Apart from very small patches within other habitats, there is no fen in the LCA. The only large lake is at Drenagh; it is heavily vegetated with reedmace, water horsetail, reed sweet-grass and common reed.

Of the rivers, several have records of the otter and the R. Roe has river water-crowfoot. The Faughanvale, Ballykelly and Bessbrook flow directly into the Foyle whereas most of the other rivers are tributaries of the Roe. The Foyle system is of international importance for Atlantic salmon and that part of the system in Northern Ireland, including the Faughan and Roe, is the largest salmon and trout fishery in the country.

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 but with exception sites of local and national significance

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)
• 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 along streams and slopes to foster regeneration and if necessary, encourage replanting of canopy species
• encourage planting of native broadleaved woodland, through appropriate grant schemes, rather than the small conifer plantations which are of poor biodiversity and landscape value

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, both dry and damp grasslands
• maintain and enhance damp 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: raised bogs/blanket bogs in the area are cut-over but many can recover

Actions:

• maintain the 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, tree removal (isolated individuals) and phasing out peat cutting - but allow heavily tree-colonised bogs to develop into woodland
• prevent reclamation of marginal upland blanket bog - important for wetland birds - but allow colonising woodland to develop

WETLANDS

Issue: rivers of importance for Priority Species and salmon

Actions:

• protect water quality of rivers through nutrient management, 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 sand pits
• monitor streams in relation to expansion of rural/urban housing and associated septic tanks/sewage treatment plants

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