Community structure of saproxylic arthropods along an urbanization gradient

Abstract

Abstract Saproxylic arthropods play essential roles in the detritus food chains of forest ecosystems by contributing to wood decomposition and nutrient cycling. Here, we examined saproxylic arthropod communities along a gradient from large forests to urban fragmented forests to clarify the effects of urbanization on the structure and composition of these communities. We found that communities could be allocated to three groups on the basis of species composition, and the groups were correlated with the urbanization gradient represented by forest size. The fragmented urban forest community had large numbers of individuals of few facultative saproxylic species, whereas many obligate saproxylic species—proportional to the abundant dead wood volume— occurred in the large forest community. As result, species richness was significantly lower in communities in fragmented urban forests than in those in large forested areas, as determined by using rarefaction curves based on the number of individuals. However, this difference was not significant when the curve was based on wood volume. Implications for insect conservationOur result suggested that forest size as urbanization scale was the most important environmental factor influencing the saproxylic arthropod communities because species composition and species diversity were affected by forest area. We need to protect large forests to conserve the overall diversity of saproxylic arthropods.