Impacts of experimental habitat fragmentation on ground beetles (Coleoptera, Carabidae) in a boreal spruce forest

A fine-scale fragmented ar ea (twenty-two 40 x 40 m clear-cuts) and a coarse-scale fragmented area (three 150 x 150 m clear-cuts) were created in a spruce forest in Norway during 1995-1996. Before and after the logging, in 1994 and 1997 respectively, ground beetles were sampled in pitfall traps between the clear-cuts and from an untouched control area. Seven eurytopic forest species accounted for 99% of the catch. In the fine-scale fragmented area the abundance of Leistus terminatus was significantly negatively affected by fragmentation, whereas in the coarse-scale fragmented area L. terminatus, Trechus obtusus and Calathus micropterus were significantly negatively affected. No clear indications of area or edge effects were found. Isolation effects probably were minimal. The ambiguity in the explanation of the results is likely to be due to species-specific and complex responses to the different aspects of habitat fragmentation.