Wetland vegetation dynamics and management in the Irish agricultural landscape of the Lough Erne region, Co. Fermanagh
The study area comprises landscape units 1 and 2 of the Fermanagh District, corresponding to the Upper and Lower Lough Erne. Recent changes in the area and distribution of Agriculture and crops, Semi-natural vegetation and Woodland and scrub land cover in the study area were assessed. Land cover analysis showed the temporal change in wetland land cover types in the study area between the periods 1991 – 1998 and compares trends in landscape units 1 and 2 with trends in Northern Ireland and the Fermanagh District. A high loss of Semi-natural vegetation and in particular Species-rich wet grassland was the dominant land cover change issue. Land cover transitions for this period indicated a change from extensive to intensive agricultural grassland. Analysis of land cover transitions for the 1998 – 2002/3 period suggested that this trend has slowed in recent years. A high frequency of reversion from the more intensive grassland type, Other agricultural grassland, to low quality Species-rich wet grassland was recorded. The area of other wetland land cover types has remained relatively stable and only a small number of transitions were recorded between these land cover types during both periods.
A stratified random sampling programme recorded the species composition of wetland and related wet agricultural grassland land cover types in relation to environment, management and landscape variables. The land cover type recorded were: Species-rich wet grassland, Poor fen, Fen, Reedbed, Swamp, Fen carr and Other agricultural grassland. Multivariate ordination and classification were used to investigate the compositional gradient of the wetlands. Analysis showed that the species composition of land cover types was not discrete but overlapped to form a continuous compositional gradient with Swamp and Other agricultural grassland representing the extremes of the gradient. Comparisons are made with similar wetland communities in Great Britain and Ireland.
Species-rich wet grassland parcels were negatively correlated with the Environmentally Sensitive Areas (agri-environment scheme) variable, indicating that the introduction of ESA schemes may not be the principal driving force for the reversion of Other agricultural grassland to Species-rich wet grassland. Other potential factors responsible for land cover change are discussed including seasonal variation in weather, socio-economic changes in agriculture and management practices. The wetlands of landscape units 1 and 2 of Fermanagh District contribute substantially to UK wetland resources. The results indicate that there is high potential for enhancing this resource through habitat gains in Species-rich wet grassland and thereby contributing to achieving UK Biodiversity targets.