Coolnasillagh ASSI

This area is of special scientific interest because of its species-rich wet grassland. Species-rich grassland tends to occur only where land management is not intensive, in particular where traditional farming practices have been maintained. As a result, it is not a widespread habitat in Northern Ireland and is often fragmented, consisting of individual fields, parts of fields or banks. Species-rich grasslands, like those found at Coolnasillagh, are a particularly scarce resource in Northern Ireland.

Coolnasillagh is situated within the Coolnasillagh River valley on the lower eastern slopes of Temain Hill, towards the eastern edge of the northern Sperrins block, at an altitude of approximately 200m above sea level. To the north of the site the soils are deep peats, and the remainder of the site is underlain by surface water humic gleys.

The underlying parent material is Tertiary Upper Basalt. The grassland is composed of two field parcels which are bisected by the Coolnasillagh Road. The fields slope in a southerly direction towards the Coolnasillagh River. Due to the above combination of slope, altitude and the westerly geographical position, the soils are kept moist.
The diverse topography with both deep and thin soils and resultant soil hydrology at Coolnasillagh has enabled the development of a range of species-rich grasslands. Often these differences in type are evident over quite small areas and locally form mosaics of semi-natural vegetation types, for example, fen meadow, rush pasture and on banks and where drier craggier conditions exist, acid grassland.

The majority of the grassland at Coolnasillagh is purple moor-grass and rush pasture vegetation. The wet areas of purple moor-grass and rush pasture contain a particular type of vegetation called fen meadow which has developed where there is a steady hydrological influence in the soil. This is typified by the occurrence of species adapted to water movement and wetter conditions, such as meadow thistle and purple moor-grass. Other distinctive species associated with fen meadow vegetation at Coolnasillagh include tormentil, Devil’s-bit scabious, carnation sedge, tawny sedge, sharp-flowered rush, lesser spearwort, selfheal and marsh ragwort.

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. In addition to the species already mentioned several orchids were recorded including, common spotted-orchid, northern marsh-orchid and early-purple orchid. Other notable plants include whorled caraway which is abundant on the site, a plant of local distribution typically found in wet grassland in this area of north County Londonderry.

Coolnasillagh is an area of semi-natural grassland managed in a traditional way. As such, it provides valuable feeding and roosting sites for a range of animals, including birds and invertebrates. Curlew and snipe were noted on the site as well as several species of butterflies, including green-veined white, meadow brown and small heath.

Site Related Documents

Site map (.PDF 635Kb), Citation document (.PDF 123KB) and Views about Management document (.PDF 60Kb).