Devenish Island ASSI

This area is of special scientific interest because of its breeding waders and 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 wet grasslands, like those found at Devenish Island, are a particularly scarce resource in Northern Ireland.

Devenish Island is a lightly grazed drumlin island in Lower Lough Erne. The island has a central ridge sloping down to the lough shore. The combination of topography and the related soil hydrology has resulted in a range of species-rich wet grasslands on the island. These vary from rush pasture to fen meadow, with base-loving plants present throughout the area.

Devenish Island has, in the recent past, been a highly significant locality for breeding waders in a Northern Ireland context. Species include curlew, snipe, redshank and lapwing, sometimes tufted duck.

The vegetation on the island is dominated by sharp-flowered rush, with a variety of grasses and sedges and in places is markedly species rich. This provides cover for nests and young birds. Other important factors for breeding birds are the heavy nature of the soils which remain wet even in summer and the adjoining lough shoreline, which provide an abundance of food for adults and young birds. The island is also relatively free from disturbance and predation with the main tourist attractions of Devenish located to the southern end of the island away from the more valuable habitats.
Purple moor-grass and rush pasture occurs over much of the island, with fen meadow present on the slopes to the north and east of the island. Fen meadow is a particular type of purple moor-grass and rush pasture. It occurs on Devenish Island where there is a steady hydrological influence flowing through the soil which results in the occurrence of species adapted to both water movement and wetter conditions. Species characteristic of this community on Devenish Island include purple moor-grass, meadow thistle, meadowsweet, bog pimpernel, Devil’s-bit scabious and tormentil.

Sedges and rushes are often important components within the sward and include tawny sedge, carnation sedge, yellow-sedge, flea sedge, and glaucous sedge with jointed rush, compact rush, sharp-flowered rush and hard rush.

On the central ridge of the island, the purple moor-grass and rush pasture tends to be less species-rich. Common species here include sharp-flowered rush, Yorkshire-fog, creeping buttercup and white clover. This poorer rush pasture is also more prevalent towards the southern end of the island, where it forms a mosaic with drier semi-improved lowland meadow with common knapweed, meadow vetchling, perennial rye-grass and crested dog’s-tail pasture.

Fringing the island’s shoreline is a slightly drier vegetation community that is base-rich and adds great diversity to the islands habitats. The community is characterised by its diversity of higher plants and has a high combined herb and sedge cover. The variation in hydrology and related topography, and past and present management has resulted in a considerable range of species present in a relatively small area. Plants of note reflecting the higher base status of the soils on this part of the island include grass-of-Parnassus, greater butterfly-orchid and knotted pearlwort.

Fen habitat provides further diversity and adds to the conservation interest of the area. The area of fen occurs both in the central lowland section of the island and also fringes much of the shoreline. In the central section where the water table is very low and the slopes are gentle, periodic flooding of the fen vegetation occurs creating a relatively expansive wetland habitat. The shoreline is inundated by water from the lough and has common reed and reed canary-grass swamps which grade into a narrow fringing fen that surrounds most of the island. The tall herb fen associated with the shoreline has species such as greater water-parsnip and flowering-rush with the more sedge rich low-lying central fen community characterised by bottle sedge with marsh pennywort, bogbean, water mint, greater bird’s-foot-trefoil and marsh bedstraw.

Devenish Island is an area of semi-natural grassland and associated habitats that have been managed in a traditional way. As such, it provides valuable feeding and roosting sites for a range of animals, including invertebrates such as ringlet, red admiral, painted lady and meadow brown.

Site Related Documents

Site map (.PDF 642 Kb), Citation document (.PDF 167Kb) and Views About Management document (.PDF 81Kb)