Patterns of diversity in a metacommunity of bees and wasps of relictual mountainous forest fragments

Naturally fragmented landscapes provide a suitable opportunity for investigating species dynamics under the sole influence of habitat fragmentation. Various approaches have used landscape attributes (e.g., patch size and connectivity) to explain patterns of species diversity and composition. We evaluated the influence that patch and landscape attributes have on bee and wasp (Hymenoptera: Aculeata) diversity (species richness and abundance) using a natural forest archipelago located in a campo rupestre (rupestrian grassland) matrix. We also assessed the effects of season on species composition (temporal β-diversity). Our analysis found higher richness and abundance of bees and wasps in the summer. There was a significant change in species composition between seasons (species replacement accounts for 88% of β-diversity), with winter communities not representing subsets of summer communities. Evaluation of the relationships between bee and wasp diversity and landscape attributes (e.g., patch size and isolation, distance between patches and continuous forest distance), only found a significant relationship for temporal β-diversity, which increases with distance from continuous forest. We propose that forest islands can be considered transient environments for many species, and so this naturally fragmented metacommunity depends on continuous forest propagules and its temporal dynamics to sustain diversity among forest islands.