Vegetation composition and structure determine wild bee communities in a tropical dry forest

Understanding the factors that influence the composition and structure of bee communities in natural habitats is critical for conservation and restoration efforts, mainly in disturbed ecosystems that are widely used for agricultural crop production, such as tropical dry forests (TDF). The aim of this study was to evaluate the effects of tree species composition and vegetation structure on the composition, abundance and species richness of eusocial and non-eusocial wild bee assemblages. Bees (19.909 individuals of 96 species) were collected in fifteen plots in different secondary succession stages in a TDF in the state of Minas Gerais, Brazil. We found a positive relationship between tree community similarity and bee community similarity, for both eusocial and non-eusocial bees. Average tree height positively affected the abundance and species richness of eusocial bees, while the abundance of non-eusocial bees was negatively affected by tree species richness. Similar tree species composition and vegetation structure between plots at the same stage of secondary succession probably determined more similar bee communities than dissimilar tree communities. Most eusocial bee species are dependent on cavities in large trees to house their colonies, while most non-eusocial bees probably prefer open habitats because they provide a greater density and diversity of floral resources, and suitable areas for ground-nesting species. Since eusocial bees represented 94% of the individuals sampled, the conservation and restoration of mature forests is of primary importance in order to increase eusocial bee diversity, and the maintenance of these areas in the vicinity of agricultural systems is crucial to increase the ecosystem service of pollination.