Sloughan and Willmount Glens ASSI

The area is of special scientific interest for its woodland and grassland habitats. Sloughan and Willmount Glens are composed of a range of vegetation communities, including oakwood with associated flushed and base-rich woodland and purple moor-grass and rush pastures at Willmount Glen. The glens are situated on the southern slope of Bolaght Mountain, with an altitude of approximately 100 – 180m above sea level.

The geology of the area is dominated by Carboniferous age sandstones of the Mullaghmore Formation. The base-rich nature of parts of the site may be due to thin limestones within the Mullaghmore sandstones, or the relatively close position of the more calcareous Bundoran Shales (also of Carboniferous age) which are a series of mudstones and limestones. A much younger (Palaeogene age) intrusive igneous dyke occurs along the length of Sloughan Glen. Soils are generally poor draining and are predominantly gleys and humic gleys.

Sloughan Glen is divided in two parts, split by a road. Within the western half of the glen, the upper slopes are covered by an acid woodland type with Sessile oak, wych elm and downy birch inter-planted with beech. Despite beech being prominent in the canopy, the area still retains a diverse semi-natural woodland community and species assemblage. The shrub layer is comprised of hazel, which is common throughout and more sparingly rowan, hawthorn and holly. The field layer is very rich where conditions are favourable, comprised of ferns such as broad buckler, hard-fern and to a lesser extent hay-scented buckler-fern.
Towards the top end of the glen where the wood is most acidic bilberry becomes a predominant component in the field layer. The ground flora is dominated by bluebell and greater wood-rush along with associates such as wood-sorrel and common dog-violet which characterise the more acidic nature of the soils.

The steep-sided, lower slopes within the western half of Sloughan Glen are wetter in parts due to flushing. This results in a less acidic assemblage of species with trees and shrubs such as ash, sycamore, alder and willows. The ground flora is very variable and depends on the strength of flushing and the local presence of beech in the canopy layer. The flushed slopes display greater species diversity characteristic of more base-rich conditions with a mixture of herbs such as lesser celandine, wood anemone, bugle and opposite-leaved golden-saxifrage typically present. The high humidity coupled with the seepage of water over the rock faces in this part of the glen provide ideal conditions for a diverse fern community which includes maidenhair spleenwort, Hart’s-tongue, hard shield-fern, and the rare beech fern. These wet rock faces also provided an ideal niche for two other rare species the rough horsetail and wood fescue.

To the east of the road, the woodland is more base-rich than within the steeper, upper reaches of the glen. The canopy is dominated by ash with an understorey comprised largely of hazel. On the northern banks of the river within this lower half of the glen, the woodland is generally less mature with dense hazel dominating a low woodland canopy. The ground flora is indicative of these base-rich conditions, with wood avens, wood anemone and primrose found throughout this area.

Willmount Glen consists of both woodland associated with the steep river glen, and species-rich wet grassland grading into heath on the upper south-facing slopes. The woodland is predominantly an acid woodland type with Sessile oak and downy birch. The shrub layer below is comprised of hazel, rowan, hawthorn and holly. The lower slopes of the woodland are wetter resulting in the dominance of ash in the canopy. The ground flora is very variable and depends on the strength of flushing. Where the wood is most acidic bilberry, hard-fern and hairy wood-rush dominate. The flushed areas display species more characteristic of base-rich conditions including sanicle, primrose, opposite-leaved golden-saxifrage and yellow pimpernel. The south-western portion of the site includes a stand of European larch which has been included due to the natural ground flora underneath the trees similar to that throughout the rest of the wood.

To the north of the woodland species-rich wet grassland extends up the hill grading gradually into wet heath on the steeper slopes. This in turn grades into acid grassland towards the top of the hill. The wet grassland here is a particular type of purple moor-grass and rush pasture called fen meadow, which develops where there is a steady hydrological influence in the soil and is typified by the occurrence of species adapted to both water movement and wetter conditions. Within these flushed grasslands, species such as meadow thistle and sharp-flowered rush are constant.
Other distinctive species associated with fen meadow vegetation at Willmount Glen include purple moor-grass, Devil’s-bit scabious, tormentil, selfheal, lesser spearwort, marsh arrowgrass, Glaucous sedge, tawny sedge and common spotted-orchid.

Willmount Glen includes an area of wet heath on the higher and steeper slopes forming an integral mosaic with the grassland. The vegetation is dominated by heather, cross-leaved heath, with frequent bilberry, purple moor-grass and a high cover of bog-mosses.

The variation in topography and related soil hydrology, and the effects of past and present management have resulted in the presence of a wide range of plant species in a relatively small area.  Recent management of the grassland and woodland has been one of minimal intervention.  As such, it provides important habitats for animals, including breeding birds, mammals and invertebrates.  It is hoped that continued sensitive management of the area will ensure that the rich assemblage of species at both Sloughan and Willmount Glens is maintained.

Site Related Documents

Site map (.PDF 764Kb), Citation document (.PDF 186Kb) and Views about Management document (.PDF 85Kb)