Conversion of Cerrado savannas into exotic pastures: The relative importance of vegetation and food resources for dung beetle assemblages

Abstract

Replacing native savannas with exotic pastures not only alters vegetation structure, but it also increases herbivorous cattle dung quantity consequently changing the food resource available for dung beetles. Therefore, this study aims at investigating the relative importance of vegetation structure regarding food resource types to determine dung beetle assemblage in Cerrado savannas and exotic pastures. We carried out a sampling of dung beetles in 30 areas of Cerrado sensu stricto and 30 in areas of exotic pastures across nine municipalities of Minas Gerais state, Brazil, by using pitfall traps baited with cattle dung and human feces. We also characterized these areas according to their herbaceous density, complexity (fractal dimension) and canopy cover. Our study demonstrates that the complete conversion of Cerrado sensu stricto into exotic pasture has a negative effect on dung beetle assemblages. The same dung types differed completely in dung beetle assemblages in native savannas and exotic pasture regarding richness, abundance, species composition and dominance patterns. These findings suggest that environmental filters in exotic pastures, as low cover canopy and herbaceous complexity simplification, probably restrict the establishment of species from Cerrado. We also found different dung beetle communities by comparing pitfall traps baited with cow dung and human feces within the same land use. Thus, alterations in food resources played a secondary role, but were also important. We suggest that increasing herbaceous complexity and canopy cover along with diversifying livestock in exotic pastures could potentially avoid the loss of dung beetles species and their associated ecosystem services.