West Fermanagh Scarplands ASSI

West Fermanagh Scarplands has a diverse range of geological and physiographical features. These support a range of habitats and associated vegetation communities of unparalleled significance in Northern Ireland. The rocks of the area are some 335 million years old and date from the Carboniferous, a time when Ireland lay near the equator.

The Limestone formations at Knockmore Hill are particularly significant. The Knockmore area supports a range of surface karst topography including some of the finest limestone pavement in Northern Ireland. Three major cave systems also occur within the site, with over 14km of surveyed passage in total.

Along the lower slopes of the scarps and in river valleys, where soils are influenced by the limestone rocks, base-rich woodlands dominated by ash with an understorey of hazel remain largely undisturbed. In combination, these represent one of the most extensive semi-natural woodlands of this type in Northern Ireland. Wet woodlands dominated by alder and downy birch also occur where soils are flushed or waterlogged.

The upper slopes of the area are dominated by large expanses of intact blanket bog which display a diversity of structural features on the bog surface. Wet and dry heaths are associated with the shallower peats.
Grassland communities are complex and reflect the range of soil, topographic and other environmental factors as well as past and present management. Grassland types range from species rich calcareous grasslands on limestone outcrops, to wet, flushed grasslands. Some of these are dominated by purple moor-grass within a sedge and herb-rich sward, generally known as "Fen Meadow".

The area includes a number of rivers and upland lakes. Lakes range from oligotrophic, those that are poor in plant nutrients, to naturally eutrophic lakes with moderate levels of enrichment providing a diversity of plant and animal species. Springs and flushes also represent a notable feature of the area, especially "petrifying" springs, where calcium-rich water seeps to the surface along the base of limestone cliffs.

The rich flora and fauna associated with this extensive and highly diverse area supports a large number of rare and notable species.