Carabids and forest edge: spatial pattern and edge effect

The spatial distribution of carabid species and the effects of edge on their diversity were studied along two repeated forest-grass transects using pitfall traps in the Aggtelek National Park, in Hungary. The location of boundaries between the adjacent habitats (forest interior versus forest edge and forest edge versus grass) was identified using moving window-technique for carabid abundances. Five groups of carabid species were distinguished: habitat generalists, forest generalists, species preferring the grass, forest specialists, and edge-preferring species. Carabids of the forest interior, forest edge and grass also separated from each other by the ordination based on abundance, suggesting that all three habitats had a distinct species assemblage, Ground and surface temperatures, cover of the leaf litter, herbs, shrubs, the canopy closure and the abundance of the carabid preys were important factors for the spatial pattern of the dominant carabids. The study revealed a significant edge effect on carabids. Carabid species richness was significantly higher in the forest edge and the grass than in the forest interior. The herb cover was the most important factor determining the carabids species richness. The study suggested that the elevated species richness of the forest edges was due, in addition to the edge-preferring species, to the presence of species typical of adjacent habitats (forest interior and grass). This highlights the importance of forest edges in nature management, as they operate as a source habitats for dispersal processes contributing to the carabid recolonisation in the adjacent habitats, after habitat destruction. This result also emphasises the significance of forest edges during the succession and regeneration of adjacent disturbed habitats. (C) 2002 Elsevier Science B.V. All rights reserved.