Strangford Drumlins and Islands 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

• To the south and west of Strangford Lough, the landscape is dominated by high drumlins
• Inter-drumlin hollows are occupied by loughs, marshy pastures and wet woodland
• The convoluted coastline is an intricate mix of inlets, drowned drumlins and rocky islets or pladdies which are a haven for wildlife
• Many small wooded estates help create an impression of a woodland landscape

Woodlands

Just under 6% of the LCA is occupied by trees and woodland. Larger areas of woodland are found mainly to the south of the road between Crossgar and Killyleagh and are associated with demesnes. The Finnebrogue estate forms the centre of this woodland concentration. These planted woodlands (Lowland woodland pasture and parkland) have abundant oak and beech, but also ash, wych elm, sycamore, hazel and sweet chestnut. Semi-natural broadleaved woodland is rare. Wet woodlands are scattered in occurrence and often found colonising former fen or marshy areas. For example, the former seashore at the Quoile Pondage NNR has areas of alder and willow and elsewhere, the fens of inter-drumlin hollows are frequently fringed with these tree species. There are few conifer woodlands in this LCA.

Grassland and Arable

Pasture is the dominant land cover in the Strangford Drumlins and Islands LCA, accounting for over 67% of the area. The majority is improved pasture (55%), but most is inter-mixed with arable fields. More continuous grassland is concentrated in the region to the north and east of Finnebrogue and between Ballygoskin and Whiterock. In these areas, much of the grassland is of poorer agricultural quality, either because it is on thin rocky soils or in damp, low-lying land. However, these grasslands are more diverse in plant species than the dominant, more improved pastures. Semi-natural grasslands are rare.

Arable fields are intermixed with pasture throughout the LCA; more solidly arable areas occur east and west of Shrigley, between Ringdufferin and Toy and east of Ringneill Bay. In the north, arable fields are often in vegetable crops.

Heaths and Bogs

In the past there were some small inter-drumlin bogs in the LCA, but today, as a result of past cutting, only very small patches remain. Almost all the former bog sites are now in carr (wet woodland) or have been reclaimed for agriculture.

Wetlands

Although there are a few small inter-drumlin fens and marshes throughout the LCA, their occurrence is concentrated in the zone between Killinchy to the north and Killyleagh to the south. Here the fen and swamp communities tend to surround lakes or have formed from cut-over bogs and include small ponds. They often have wet woodlands to give a locally rich diversity of habitats. Notable plant species include, bog pimpernel, least bur-reed, floating mud-rush, cyperus sedge and the great spearwort; Northern Ireland Priority Species - curlew and yellowhammer - have also been recorded in some of these sites. The most extensive area of wetland communities lies in and around the Quoile Pondage NNR. The present freshwater lake was created by the construction of a tidal barrier across the Quoile estuary in 1957. Since that time, succession has led to a diversity of habitats rich in wildlife. The natural colonisation of the former seashore has resulted in marsh plants growing along the river fringes, with reed-beds, rushy grassland and alder or willow scrub in old muddy bays. Woodland of oak and ash is developing on the higher, stony shores. Periodic rises in the water table helps maintain distinct zones of vegetation.

The freshwater lake created by ponding the Quoile is an example of an eutrophic lake, that is, high in plant nutrients. Insect life is rich providing food for fish such as rudd and eels. In turn, these attract grey herons, cormorants and grebes. The Quoile is also a site for migrating wading birds in the spring and autumn, whilst in summer, swans and many breeding wildfowl appear, including the scarce gadwall. In winter, large numbers of wigeon and other ducks may be seen. Although having a high biodiversity, in recent years the Quoile has been affected by pollution incidents. One example of a Mesotrophic lake, an increasingly rare type of lake that has potentially the highest macrophyte diversity of any lake type, is found at Ballymartin Lough. Marl lakes have a high base status, a specialised flora and are generally rare in Northern Ireland; Tullyveery Lough and Heron Lough are unusual examples in the east of Northern Ireland, most occur in Fermanagh.

There are few rivers of note in the LCA

Strangford Lough Shores

The seaward boundary of the LCA is not a clear one because of the convoluted coastline with its many inlets, bays and islands. These form an important part of the LCA, through their contribution to the landscape and to the biodiversity. Sheltered inlets and bays, such as Ardmillan Bay, tend to have muddy shores, often with a fringe of coastal saltmarsh, a rare community in Northern Ireland, on their landward edge. Mud snails, which graze on microscopic algae and bacteria on the surface of the mudflats, are eaten by shelduck and other waterfowl. Lugworms, ragworms, catworms, tellin shells and burrowing amphipod 'shrimps' live within the sediment. These organisms exist in enormous numbers and form an important part of the diet of the 45,000 wading birds that winter on Strangford Lough. (Strangford Lough has been designated as Northern Ireland's first Marine Nature Reserve). The diversity of some mudflats and bays in the LCA, for example Ardmillan Bay and Ringneill Bay, are threatened by the growth of Spartina; this forms an almost pure community and has low biodiversity.

The sheltered waters, rocks and islands attract seabirds, particularly terns, black-headed gulls, black guillemots and eider duck all of which breed and feed within and close to the 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, but including the NI Priority Habitats Lowland woodland pasture and parkland at Finnebrogue estate and wet woodlands within the Quoile Pondage NNR.

Actions:

• enhance the biodiversity value of demesne woodlands by discouraging any further felling or pollarding; by retention of fallen and veteran trees (particularly for bryophytes, ferns, fungi and fauna); ensure that hazel scrub is not cleared
• enhance biodiversity through measures to improve and extend woodland cover such as The Woodland Grant Scheme or The Farm Woodland Premium Scheme; management plans for demesne woodland should be directed toward their survival, through natural regrowth or planting of native broadleaf species
• encourage control of grazing in broadleaved woodlands to foster herb layer and regeneration and if necessary, encourage replanting of canopy species
• further study of the history and ecology of broadleaved woodlands within the LCA, particularly any ancient and long-established, as a key to future management
• ensure conservation of wet woodlands by allowing succession to take place and installing fencing to prevent trampling; ensure that loss does not occur through drainage, reclamation, landfill or dumping/tipping

GRASSLAND AND ARABLE

Issue: improved pastures and arable land of low biodiversity value

Actions:

• encourage (through participation in Environmental Schemes) adoption/continuance of less intensive management of pastures to allow reversion to/continuance of more species-rich grassland maintain and enhance damp grassland by where, possible, restricting field or arterial drainage
• maintain and improve field boundaries, especially hedgerows where they occur through adoption of correct cutting cycles; hedge laying and replanting where necessary; leave saplings uncut to develop into hedgerow trees; avoidance of spraying with fertilisers, slurry, herbicides; provision of wildlife strips and conservation headlands around fields; and limitation of field amalgamation
• leave stubble over winter, rather than autumn ploughing to increase food resources for farmland birds; spring-sown cereals are beneficial to farmland birds
• ensure that further clearance of boulders does not occur on pastoral or arable land

HEATHS AND BOGS

Issue: once existent inter-drumlin bogs have been lost to cutting, with only very limited patches remaining today

Actions:

• maintain the integrity of those small remaining inter-drumlin bogs by for example, preventing infilling, fly-tipping, fires, new drainage and mechanised peat cutting - applies particularly to intact bogs but cut-over bogs can provide important habitats for birds and invertebrates
• consider restoration of bog habitats through appropriate water level management, removal of individual colonising trees and phasing out peat cutting - applies particularly to formerly intact bogs affected by recent mechanical cutting
• monitor use of cut-over bogs to ensure that important micro-habitats are not lost, that the large tracts of land required by predator birds are not broken up by planting and other uses, and that the needs of over-wintering and breeding wetland birds are met

WETLANDS AND LAKES

Issue: the NI Priority Habitats fens, eutrophic standing waters, mesotrophic lakes and marl lakes are threatened by nutrient enrichment

Actions:

• promote and encourage adoption of Countryside Management guidelines so that fens and lakes are not polluted by releases from silage effluent, herbicides, pesticides, fertilisers or sheep dip; ensure that further eutrophication does not occur as a result of nutrient-rich surface waters from surrounding farmland
• monitor streams in relation to expansion of rural/urban housing and associated septic tanks/sewage treatment plants
• prevent further loss of fens through drainage, reclamation, land-fill, new woodland planting and encroachment by scrub woodland; prevent dumping and fly-tipping and encourage removal of rubbish; care should be taken to divert the flow of nutrient rich water from agricultural land away from fens, so that sites do not become damaged by a change in species composition
• carefully assess any proposals for arterial and field drainage near to fens so that the water table is not lowered to the extent that fens are affected
• monitor effects of recreation, including fishing, on shoreline communities (reedbeds, fens etc.)

Strangford Lough Shores

Issue: mudflats in this LCA are often fringed with the NI Priority Habitat coastal saltmarsh; Ardmillan Bay and Ringneill Bay are threatened by the growth of Spartina, which has low biodiversity

Actions:

• protect rare coastal saltmarsh communities from sources of pollution and waste tipping, in addition to damaging activities such as land-fill and construction
• protect mudflats from potential impacts of nutrient enrichment, land claim, coastal defences, dredging and human disturbance
• ensure that NI Priority Species, rare plants and RSPB Red List Species are protected from factors such as new development, erosion, waste tipping and pollution
• monitor the spread of the invasive alien plant Spartina angelica in Ardmillan Bay and Ringneill Bay and its impact on local biodiversity, to facilitate population control and conservation management
• monitor the effects of recreation in Strangford Lough, including boating and fishing, on those rocks and islands which attract breeding seabirds

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