Temporal and spatial variation in carabid assemblages from the United Kingdom Environmental Change Network

This paper presents analyses of the data from the first 7 years of the UK Environmental Change Network (ECN) carabid monitoring programme. The 10 ECN terrestrial sites for which results are available represent a wide range of habitats, from lowland arable farmland to upland moorland, and correspondence analysis reveals the strong association between habitat and species composition. At all sites carabid assemblages are dominated by a small proportion of the species found at the site. There are strong year-to-year fluctuations in the proportions of individual species and a large percentage of species are observed only sporadically. This has major implications for the conservation and monitoring of carabids. Simple summary statistics, such as species richness or diversity do not adequately reflect variation in species composition and are unlikely to respond quickly to environmental change. The considerable annual variation makes the detection of relationships with sources of environmental change a difficult task, particularly for the rarer species of primary conservation interest. Analysis should therefore include measures based on the dominant species to provide an early warning system for environmental change. (C) 2002 Elsevier Science Ltd. All rights reserved.