Response of the dung beetle community to different climatic zones: does the land use system matter?

Abstract

The conversion of Brazilian savannas into exotic pastures leads to biodiversity loss of dung beetles and decrease in their ecological functions. The insect communities active in these ecosystems are simplified, and therefore they are more susceptible to climatic environmental variations than communities from more complex and stable habitats. We hypothesize that the dung beetle communities from exotic pastures will present more significant differences between climatic zones, when contrasted to communities from Brazilian savannah at the same region. We verify which variables (purpose of production, type of management, percentage the habitat por buffer, soil penetration resistance, pasture area and herd size) affect more the dung beetle community in exotic pastures. We carried out this study in 48 areas of native Brazilian savannas and exotic pastures distributed across four bioclimatic zones: BZ1 - hot with three dry months, BZ2 - hot with 4-5 dry months, BZ3 - sub-hot with 4-5 dry months and BZ4 - mesothermal with 4-5 dry months of Minas Gerais State - Brazil. In each BZ were selected six areas of Brazilian savanna and six areas of exotic pasture. In natural areas, the species richness, abundance, and biomass of beetles did not differ between the bioclimatic zones, unlike the exotic pastures. The composition of the dung beetle community was different between land-use systems and between bioclimatic zones; the interaction between the two factors was also significant. The best model suggested that all the six variables combined explained about 91% of the total variability in species composition observed between sampling sites.