Regional variation in the cover, species composition and management of blanket bog

Abstract

A structured, spatially explicit assessment of the distribution of heath and mire in Northern Ireland, based on land classification, is developed. This gives perspective to land use and ecological resources in the uplands of Northern Ireland (NI) and increases the ecological information available to land use decision-makers. Thus the area of intact, unmanaged ombrotrophic mire, defined by vegetation community criteria, was estimated as 9% (157 km 2) of the upland heath and mire vegetation in NI. This represents 1.2% of the land area of NI and emphasises the nature conservation importance of the resource. Stepwise forward selection and canonical correspondence analysis, based on a stratified vegetation, environment and management sampling programme, indicate the relative importance of factors associated with the composition of ombrotrophic mire. Slope, degree of waterlogging and peat depth were the main environment attributes governing composition. There was also major association between biogeographic location and vegetation community composition, indicating the importance of spatial variation in conservation management strategies. Grazing intensity was shown to be the main management factor associated with variation in species composition. Burning, disturbance and structural intactness of the peat profile had secondary effects. Relationships between different types of management and site locational attributes, demonstrated formally within the model, show that peatland management strategies need to consider spatial variation at the landscape scale.