Blackwater 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 cover c. 4.5% of the LCA (compared with c. 5.6% for NI as a whole), the majority associated with estates - some of the largest estate woodlands in Northern Ireland
• several small modern mixed plantations scattered between Caledon and Aughnacloy
• grassland accounts for c.84% of the land cover (compared with 71% for Northern Ireland as a whole), almost all in improved pasture that is generally of low biodiversity
• areas of wet grassland alongside the river that are relatively species-rich and important for wetland birds
• rare lake types, particularly marl lakes, with specific species
• rivers with Priority Species and important for salmon and trout

Woodlands

Woodlands cover c. 4.5% of the LCA, the majority associated with estates (lowland woodland pasture and parkland) including very large examples such as Tynan Abbey and Caledon House, as well as smaller ones such as Cottage Hill and Crilly House. The adjacent Caledon House and Tynan Abbey form extensive woodlands and parklands with a wide range of tree species; beech, ash, oak, and sycamore are common, but there are also frequent horse chestnut and some elm. Firs are common along parts of the edge-planting at Caledon, and Scots pine and larch are also frequently intermixed with the broadleaves. At Lemnagore Wood there is modern conifer planting, but also broadleaved woodland; some of the broadleaved woodland has large mature trees related to the estate planting, but other trees are younger, especially along the line of the former railway cuttings. Ferns are abundant, as are mosses and lichens, but in some parts of the planted estate woodland the dominance of cherry laurel in the understorey reduces the herb layer.

Outside of estate woodland, most of the remaining woodlands are small, managed by the Forest Service and generally mixed woodlands. One of the few woodlands not of modern planting is Knockaginney FNR. This small isolated woodland has an extensive range of trees and shrubs. The predominant tree is oak, many arising from coppice shoots from an earlier woodland, and there are some planted beech. Hazel, holly, blackthorn and rowan form an understory, together with spindle and guelder rose. Fallow deer are present.

Grassland and Arable

Grassland accounts for c.84% of the land cover (compared with 71% for Northern Ireland as a whole), almost all in improved pasture. This generally has low biodiversity as a result of relatively intensive management, but the extent of improvement and management varies. 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, but where the management is less, for example towards damper areas, the diversity may be less reduced. Arable land (includes grass re-seeding) is around the average for Northern Ireland at c.6%.

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 poorly-managed, overgrown and gappy though with frequent hedgerow trees, principally ash; better management would increase the biodiversity of the hedgerows and as a consequence, that of the farmland.

Although improved pastures dominate, throughout this low-lying area there are field corners, individual fields and small groups of fields that are not managed so intensively and have not been recently drained and reclaimed. In these areas there may be damp meadows (lowland meadows) that, because of the relatively high base status of some soils developed from limestone till, can be rich in plant species. In other situations, fields are relatively species-poor and rush-dominated. These damp grasslands have been declining habitats in Northern Ireland, as in the UK generally, as field and arterial drainage was intensified. Despite past drainage schemes Northern Ireland retains a significant proportion of the UK area of these habitats. In addition to the plant species, the habitats are important for breeding waders and in this LCA lapwing, curlew and snipe have all been recorded. Of particular note are the high numbers of breeding snipe recorded at Knockbane in the extreme south, and at Ravellea, and of lapwing at Annaghroe.

At the Annaghroe, River Blackwater IBA, the grazed, periodically flooded meadows situated alongside the river are managed to provide flooded meadows for breeding waders and wintering wildfowl, in particular white-fronted geese.

Heaths and Bogs

There are no significant areas of heath or bog in the LCA.

Wetlands and Lakes

There are several small patches of fen in the LCA, usually around small lakes as at Tulllybrick Lough ASSI. Here, the edge of the lough is fringed by stands of great fen-sedge along with other commoner swamp types. Behind the swamp fringe the marginal vegetation varies between wet woodland, tall herb fen and most notably to the east, by calcareous tall sedge-rich fen. These fen vegetation types grade into fen meadow on the drier ground behind. In addition to the rarity of the lake type itself and of some of the vegetation communities present, the site also contains a number of locally rare plant species. There is more extensive fen at Knockbane.

Tulllybrick Lough lies in a small inter-drumlin wetland and appears to be fed mainly by calcareous springs. As result it has the typical characteristics of marl lakes, with very clear water and extensive growths of stonewort. This lake type is concentrated in Femanagh and such lakes are relatively rare elsewhere; they are vulnerable to phosphate accumulation. Tynan Abbey Lake is also a marl lake. Elsewhere, there are examples of lakes classed as eutrophic standing waters, for example on the Caledon estate, which have diverse macrophytes. However, several lakes in the LCA have been enriched by runoff from agricultural land.

The Tynan River and Blackwater River both have river water-crowfoot and the white- clawed crayfish. The Blackwater is a salmon river (also trout and dollaghan). The Oona Water is important for brown trout fishing. The otter is widespread.

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: extensive examples of demesne woodland (some of the largest in Northern Ireland) and several small modern plantations

Actions:

• enhance the biodiversity value of demesne/parkland woodland through control of grazing and felling; by encouraging planting of saplings of the standard trees rather than conifers; 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 planting of native broadleaved plantations, through appropriate grant schemes, rather than the small conifer plantations which are of poor biodiversity and landscape value
• encourage conversion of mixed plantations (mostly Forest Service) to broadleaves.

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 - in this LCA applies particularly to wet grasslands
• maintain and enhance floodplain 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.

WETLANDS

Issue: fens in Northern Ireland are a large proportion of the UK resource; this LCA forms part

of the extensive belt of inter-drumlin and river valley fens of Armagh and Down

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: rare types of lakes and rivers of importance to Priority Species and for salmon

Actions:

• protect water quality of lakes and 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
• monitor streams in relation to expansion of rural housing and associated septic tanks/sewage treatment plants
• continue cross-border co-operation to ensure protection and enhancement of water quality
• promote establishment of riverside vegetation and return to annual flooding of land (possibly with compensatory schemes) to accommodate wetland and migratory species

Click here to return to the Northern Ireland LCA Map