Variation in the structure of habitat affecting solitary bees and wasps composition in urban forest fragments of Atlantic Forestry in Northeastern Brazil

Abstract

Habitat disruption affects pollinator populations by reducing the suitable habitat. Determining habitat characteristics which explain variation of the pollinator composition is important in understanding how habitat alteration can affect their population dynamics. We related compositional patterns of solitary bees and wasps to environmental factors in urban fragments of forest in Salvador, Bahia (13º01’ S and 38º31’ W), Brazil. The study was conducted from November 2001 to January 2003. Bees and wasps were sampled in 14 selected points distributed along the two fragments. The habitat variables were measured in each point. Canonical Correspondence Analysis (CCA) was performed to determine the factors affecting the composition of bees and wasps. Colonization of trap nests by bees and wasps was significantly influenced by the microhabitat characteristics, such as forest canopy, density of understory and sunlight exposition. However, the composition of Euglossina did not vary significantly along the habitat quality gradient. Results of this study show a tendency of richness and abundance decrease in highly disturbed points. More experiments in habitat requirements are needed to predict the effect of habitat alteration over pollinators’ population.