Functional spatial scale of community composition change in response to windthrow disturbance in a deciduous temperate forest

Community dynamics in local habitats are affected by landscape characteristics such as the area and connectivity of surrounding habitats at a functional spatial scale where the community responds to landscape structure. However, the functional spatial scale at which community composition is affected by landscape structure has never been explored. We assessed the functional spatial scales of composition change in birds and in three types of arthropod communities (canopy, forest-floor and flying ones) with regard to landscape heterogeneity resulting from a large typhoon in a temperate forest of Japan. We examined the effects of tree-fall disturbance on the communities at various spatial scales, with special attention to compositional evenness. The spatial scale of the best-fitting model, which was selected from models fitted to the disturbance area at stepwise spatial scales, was interpreted as the community-specific functional spatial scale. The composition of all communities studied was all significantly dependent on gap area. The functional spatial scale was highest in birds (370 m in radius), intermediate in flying arthropods (90 m) and lowest in canopy and forest-floor arthropods (10 m). This result may reflect typical dispersal ability and the spatial range of resource use in the community. Compositional changes in each community were consistent with theory regarding traits and responses of component taxa, although the enhancement of evenness was observed only in the arthropod communities. These results imply that management and reserve selection based on functional spatial scales can be effective in the conservation of biodiversity and ecosystem services at the community level.