A spatial scale assessment of habitat effects on arthropod communitiesof an oceanic island

摘要

Most habitats in the Azores have undergone substantial land-use changes and anthropogenic distur-bance during the last six centuries. In this study we assessed how the richness, abundance andcomposition of arthropod communities change with: (1) habitat type and (2) the surrounding land-useat different spatial scales. The research was conducted in Terceira Island, Azores. In eighty-one sites offour different habitat types (natural and exotic forests, semi-natural and intensively managed pastures),epigaeic arthropods were captured with pitfall traps and classified as endemic, native or introduced. Theland-use surrounding each site was characterized within a radius ranging from 100 to 5000 m. Non-parametric tests were used to identify differences in species richness, abundance and compositionbetween habitat types at different spatial scales. Endemic and native species were more abundant innatural forests, while introduced species were more abundant in intensively managed pastures. Naturalforests and intensively managed pastures influenced arthropod species richness and composition at allspatial scales. Exotic forests and semi-natural pastures, however, influenced the composition ofarthropod communities at larger scales, promoting the connectivity of endemic and native speciespopulations. Local species richness, abundance and composition of arthropod communities are mostlydetermined by the presence of nearby natural forests and/or intensively managed pastures. However,semi-natural pastures and exotic forests seem to play an important role as corridors between naturalforests for both endemic and native species. Furthermore, exotic forests may serve as a refuge for somenative species.