Knocknashangan 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 Knocknashangan, are a particularly scarce resource in Northern Ireland.

Knocknashangan is situated on a landscape of rolling hills approximately 4km south-east of Garrison. It lies on the edge of the uplands with an altitude of approximately 140m above sea level. The area covers part of Gorteen hill and slopes quite steeply in places.

The site is underlain by Carboniferous age rocks, dominated by limestones belonging to the Dartry Limestone Formation. These rocks formed in relatively shallow water and are base-rich having a significant calcium carbonate content. The soils at Knocknashangan are derived from the parent rock, and the resultant soils have poor drainage characteristics and are known as surface water gleys.

Due to a combination of factors such as slope, altitude and the westerly geographical position, these soils are kept consistently moist. This combination of underlying geology, topography and the related soil hydrology has resulted in a complex range of species-rich wet grasslands within a small area. These vary from species-rich rush pastures to fen meadow and wet heath, with base-loving plants present throughout the area.

The vegetation at Knocknashangan is dominated by wet grassland of the purple moor-grass and rush pastures type, with occasional pockets of flushed grassland and wet heath. Fen meadow is a particular type of purple moor-grass and rush pasture. It occurs on Knocknashangan 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. Here, species such as meadow thistle and sharp-flowered rush are constant. Other distinctive species associated with fen meadow vegetation at Knocknashangan include purple moor-grass, tormentil , devil’s-bit scabious, heather, bog pimpernel, selfheal, carnation sedge, tawny sedge, flea sedge and glaucous sedge. The predominant moss within the grassland is glittering wood-moss which is adapted to the unique conditions at Knocknashangan; other mosses present include bog groove-moss and pointed spear-moss.

In addition to the grassland, Knocknashangan also has small areas of wet heath vegetation which occur in a mosaic with the fen meadow on the upper slopes. This wet heath vegetation has very similar vegetative characteristics to the grassland apart from a noticeably higher coverage of dwarf shrub species such as heather and cross-leaved heath. The wet heath has similarly high species diversity to the surrounding grasslands due to both the traditional management practices and the influence of base-rich waters flushing through the soils.

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 vegetation communities described above the following species of note was recorded in proliferation - lesser butterfly-orchid.

Knocknashangan 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. The latter includes the marsh fritillary butterfly which is well adapted to the habitats present at Knocknashangan, in particular the abundance of its larval foodplant devil’s-bit scabious and the area’s southerly aspect.

Site Related Documents

Site map (.PDF 545Kb), Citation document (.PDF 135Kb) and Views about Management document (.PDF 65Kb)