Castlereagh Slopes 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

• steep northern slopes of the Castlereagh Hills and their extension southwestward
• largely occupied by improved pastures but with significant arable land near Ballylesson
• large demesne woodlands, particularly in the southwestern part of the LCA
• threats to habitats from urban expansion, particularly in the Belvoir-Newtownbreda-Carryduff corridor.

Woodland

Woodland occupies approximately 4% of the LCA; most of this is broadleaved or mixed woodland and originating from demesne planting. The two largest examples of demesne woodlands (Lowland woodland pasture and parkland) are at Hydebank and Purdysburn Hospital; both are of mixed planting with a wide range of tree species that includes oak, beech, elm (though declining through disease), lime, sycamore, larch, and many other specimen conifers and broadleaves. Belvedere and New Grove are older estates with broadleaved planting, principally of beech, sycamore and ash. Groves and avenues of lime are also found in some of these estates. Estate planting was not confined to the land around the house, but also to 'landscaping' the surrounding agricultural land. This included planting alongside streams as at Drumbo Glen (ash and hazel woodland planted with elm, oak, beech, larch and Scots pine) and Cregagh Glen (sycamore, beech, Scots pine and larch). Information on Priority Species is sparse, but red squirrel has been recorded at Hydebank and yellowhammer at Purdysburn.

Estate woodland in this LCA is under threat; expansion of housing has already seen its loss or severe depletion. Examples include Alderwood, where the mixed parkland and grasslands have been cleared and built over, and The Pines. Trees have also been lost to road building and new water mains as at Hydebank and Purdysburn. There is a lack of maintenance of some of these woodlands also, particularly those in public ownership; for example, many of the trees at Purdysburn have been felled because they were over-mature, but they have not been replaced. Generally, as canopy trees become post-mature they are not being replaced; saplings and young trees are often of the more invasive species so that the composition is gradually changing. The understorey in many estate woodlands is unmanaged and has become dense (e.g. with rhododendron) excluding light and therefore limiting or excluding ground flora. Public access and associated trampling has also led to loss of ground flora, as at Cregagh Glen.

Outside of the estates, woodland is scarce and confined to patches alongside small streams flowing down the steep slopes of the Castlereagh Hills; these are predominantly ash-hazel woodland.

Grassland and Arable

Grassland accounts for approximately 65% of the land cover of the LCA, the vast majority being in improved pastures. The biodiversity is generally low as a result of reseeded pastures and heavy use of slurry and inorganic fertilizers; the hedgerows that form most of the field boundaries provide habitats for farmland birds. Hedgerows are managed well, but there has been some field amalgamation. Continued good management of hedges (that could include laying and replanting of hedgerow shrubs; allowing tree saplings to develop into mature trees or planting saplings; and limiting the use of herbicides, pesticides and fertilizers at the foot of the hedgerow) should help retain and enhance biodiversity. Farmland is under threat from urban expansion, particularly along the Newtownbreda - Carryduff.

There are areas of poor quality pastures in the LCA mostly resulting from a lack of intensive management, as for example the grounds of Purdysburn Hospital, or from a combination of poorer management and exposed sites with steep slopes, e.g. Braniel Hill. At the latter sites, gorse scrub may also occur. Generally, the biodiversity is not high.

Arable land, (which includes land prepared for grass reseeding) occupies around 13% of the LCA. It is scattered throughout the LCA among the fields of improved pastures, but there is a more concentrated area of genuinely arable land between Drumbo and Purdysburn.

Wetlands

There are no significant areas of standing water in the LCA. Many small streams flow north from the hills and slopes towards the River Lagan. Whilst there are no records of the presence of Priority Species in these streams, it is important that they should not be polluted.

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: demesne woodlands, which are NI Priority Habitat Lowland woodland pasture and parkland, are under threat from urban expansion and lack of maintenance

Actions:

• there is a need for planned management of estate woodlands and stronger limitation on expansion of housing if these are to be retained; avoid depletion of woodland through road building and new water mains; restrict public access at Cregagh Glen to minimise trampling
• enhance the biodiversity value of demesne woodlands at Hydebank and Purdysburn 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
• encourage control of grazing in broadleaved woodlands to foster herb layer and regeneration and if necessary, encourage replanting of canopy species, particularly post-mature; removal of invasive species could increase the diversity of ground flora, especially where the canopy species are not beech
• further study of the history and biodiversity of broadleaved woodlands within the LCA, particularly any ancient and long-established, as a key to future management
• 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; farmers and landowners could be encouraged to plant field corners or set-aside fields

GRASSLAND AND ARABLE

Issue: low biodiversity of improved pastures and intensively managed arable land; farmland along the Newtownbreda-Carryduff corridor is under threat from urban expansion.

Actions:

• planning controls must be strictly enforced to halt loss of farmland along the Newtownbreda-Carryduff corridor
• 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; excluding grazing of poor quality pastures could allow these sites to develop into treed scrubland
• 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 through a move to organic farming; 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

WETLANDS AND LAKES

Issue: small streams and the River Lagan should be safeguarded from incidences of pollution

Actions:

• promote and encourage adoption of Countryside Management guidelines so that streams and rivers are not polluted by releases from silage effluent, herbicides, pesticides, fertilisers or sheep dip; ensure that 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

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