The Lough Macnean Valley Biodiversity Profile
Key Characteristics
- woodlands cover around 5% of the LCA, roughly the same as for Northern Ireland as a whole; of this about a quarter is broadleaved and mixed woodland
- broadleaved woodlands are small but well scattered, especially on the slopes to the north of Lower Lough Macnean
- upland mixed ashwoods and hazel woods dominate, but some areas of upland oakwood; wet woodland is common around the shores of the loughs, especially Lower Lough Macnean
- grassland accounts for around 71% of the land cover, approximately the same as for Northern Ireland as a whole; about half of the grassland is improved pasture, mainly in the eastern half of the LCA
- areas of grazed limestone pastures and of 'fen-meadow' that are species rich
- little peat bog or heath and that present is degraded as a result of over-grazing
Woodlands
Woodlands cover around 5% of the LCA, roughly the same as for Northern Ireland as a whole; of this about a quarter is broadleaved and mixed woodland. Coniferous forest is dominated by Sitka spruce with lodgepole pine and some Norway spruce. This is generally of low biodiversity.
Broadleaved woodlands are small but well scattered, especially on the south facing slopes to the north of Lower Lough Macnean. Hazel and ash woodlands are common, including Carrickalough Wood and parts of Lurgan River Wood. They continue in the Aughrim - Templenaff area and eastward to Drumaran. Lurgan River Wood not only has calcicolous (favouring lime) ash-hazel woodland (upland mixed ashwoods) along the lower main valley slopes, but also localised acid oak-birch woodland along the upper valley. Hazel is the predominant tree component of the calcicolous woodland, forming a low canopy cover while ash, its constant companion, extends above this low canopy layer, frequently in association with downy birch and to a lesser extent with goat willow. In the lower canopy hazel is generally accompanied by hawthorn with holly, blackthorn and rowan. There is poor to moderate diversity in the herb layer because of grazing, but lichens and mosses are frequent to abundant. This structure and composition is typical of the ash-hazel woodlands on these south-facing slopes.
The acid woodland canopy of Lurgan River Wood is comprised of well-grown sessile oak, downy birch and rowan (upland oakwood); a few planted Scots pine indicate that the woodland has at least been modified. The understorey is comprised of a mixture of downy birch, hawthorn, holly and rowan. The herb layer tends to be poor but there is a good cover of bryophytes.
Wet woodland is common along the shores of Lough Macnean, dominated by alder and willows, with oaks, birch and ash in drier parts. Corry Point Wood is a semi-natural broadleaved drumlin wood with components of flush woodland. The woodland along the shore is generally of an inundation type with a small swamp woodland present at the northern end and all fringed by a reedbed. The dry drumlin woodland has a mature canopy predominantly of ash with scattered birch with local stands of oak and beech that indicates that the wood has at least been landscaped. The widespread understorey is comprised of hazel and holly with regenerating ash saplings. Mosses and lichens are widespread and are the dominant ground cover; wood rush is locally dominant.
Gardenhill is one of the few remaining areas of former estate woodland (lowland woodland pasture and parkland). It was present in 1834, indeed the planting of hedges and woods was extensive, and it also included areas of native scrub, predominantly hazel, that are present today. The nearby Carrickalough Wood, a hazel-ash dominated scrub, with areas of limestone grassland, has some notable species including Welsh poppy and the buttercup goldilocks.
Grassland and Arable
Grassland accounts for around 71% of the land cover, approximately the same as for Northern Ireland as a whole; about half of the grassland is improved pasture, mainly in the eastern half of the LCA. 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. It should be noted in this LCA that the distinction between improved pastures and grazed limestone grasslands is difficult to make, especially by satellite-derived mapping, so that the 'improved pastures' may be over-estimated.
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, hedges are found in the lower, flatter areas of improved grassland where they tend to be reasonably well-maintained. On the rush-infested fields, many of which are abandoned or only lightly grazed, hedges are overgrown and gappy and the shrubs are invading the fields.
On the neutral, heavy wet soils developed from calp till, there are areas of unimproved neutral/mesotrophic grassland, referred to as 'fen-meadows'. These are characterised by purple moor grass - meadow thistle grassland (purple moor grass and rush pastures) that have a diversity of species that includes jointed rush, purple moor grass, carnation sedge, tawny sedge, glaucous sedge and flea sedge, with meadow thistle. In damper valley floors, fens grade into marshy grasslands (see below).
Heaths and Bogs
There is little peat bog in the LCA and of that, some has been planted to conifers while the remainder is cut-over; there is no intact bog. Blanket bog occurs along the northern boundary and is most extensive in the Mullyard-Largan River region. Although blanket bog is a Priority Habitat, and important at the European as well as the national scale, that occurring here is of low interest to biodiversity. Like the wet heathland (upland heathland) which it adjoins, the blanket peat is degraded by overgrazing. A small section of Carrickbrawn ASSI falls into the LCA and is notable for the Cornish heath (Erica vagans) that occurs in Ireland at two sites - one on the dunes at Murlough in County Down, where it is probably a garden escape, and here, where it may be native.
Wetlands and Lakes
The shores of both Upper and Lower Lough Macnean have good examples of wet woodland and of fen and reedbed communities. For example there are areas of low, species-rich sedge fen characterised by marsh pennywort, common sedge, common spike rush, water horsetail and sharp flowered rush. Extensive reedbeds of common reed occur around both loughs but especially Lower Lough Macnean. Martincrossagh Lough also has a fringe of fen.
On the flat wetlands inland, marshy grasslands grade into fen; characteristically these areas have bottle sedge, common sedge, carnation sedge and star sedge combined with sharp flowered rush. The marsh marigold may also be prominent together with meadowsweet.
Lough Hamul is classed as a bryophyte lake by the Northern Ireland Lake Survey; that is, it is peaty with a low pH and unproductive. In contrast Martincrossagh Lough is a mesotrophic lake of the Isoetes-Lobelia type - a natural lake type that contains most of the Northern Ireland records for both type species. Mesotrophic lakes have a middle level of nutrients between nutrient poor (oligotrophic) and nutrient rich (eutrophic). Mesotrophic lakes potentially 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.
The white-clawed crayfish has been recorded from Upper Lough Macnean. Islands in the loughs are also important for breeding waders, including lapwing, snipe and curlew.
Key Issues
General actions for UK and NI Priority Habitats and Priority Species are detailed in the Habitat Action Plans and Species Action Plans sections.
WOODLANDS
Issue: woodland cover at about that of Northern Ireland as a whole - low and of variable biodiversity value
Actions:
- further study of the history and ecology of 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 broadleaved plantations rather than small conifer plantations which are of poor biodiversity and landscape value
- discourage clearance of hazel scrub from the limestone slopes
GRASSLAND AND ARABLE
Issue: poor biodiversity of improved pastures, but areas of species-rich neutral grasslands, including 'fen-meadows'
Actions:
- maintain and improve field boundaries especially hedgerows in areas of improved pasture. 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; thus ensure that limestone pastures are not treated with fertilizers and slurry and that 'fen-meadows' are not drained
HEATH AND BOGS
Issue: loss of heathland and decline in its biodiversity
Actions:
- promote membership of ESA or other environmental schemes through consultation with farmers and thereby
- control grazing intensity on existing heathland to encourage development of heathland and of heather of different ages
- discourage 'reclamation' to pasture fields around the heathland margins
- discourage afforestation
Issue: raised bogs/blanket bogs are of national and international importance, but this area has little and it is cut-over and degraded by overgrazing
Actions:
- restore bog habitats through appropriate measures such as water level management, phasing out peat cutting, removing or limiting grazing
- prevent new forest planting on raised/blanket bog
WETLANDS
Issue: fens in Northern Ireland are a large proportion of the UK resource, this LCA has significant shoreline fens and fens that grade into marshy grassland
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 lakes and rivers, including examples of mesotrophic lakes (these are often threatened by nutrient enrichment) and lakes 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
- continued monitoring of streams below forestry activities for pH, nutrients and sediment load
- monitor streams in relation to expansion of rural housing and associated septic tanks/sewage treatment plants
