Response of dung beetle taxonomic and functional diversity to livestock grazing in an arid ecosystem

Abstract

1. The consequences of cattle raising on biodiversity have been extensively explored in the humid forests; however, its impact in dry forests is less understood. The Dry Chaco is the largest dry forest in South America and deforestation rates in this region are one of the highest in the world. Dung beetles play a key role in cattle dung burial, leading to improved soil quality and reducing parasite incidence. Consequently, sustainable management of cattle should preserve this taxon and associated ecosystem services. 2. We compared the taxonomic and functional response of dung beetles to two different livestock managements with different conservation of tree cover (open pastures and silvopastoral systems) in the Dry Chaco. 3. Through GLMM analysis, we compared richness, species abundance, taxonomic and functional composition, and three indices of functional diversity between native forest and cattle systems and explored the role of environmental variables to explain changes. 4. We captured 2838 individuals of 45 species. Taxonomic and functional richness and functional composition were similar among habitats. Total abundance was greater in the native forest than in silvopastoral systems and pastures. However, functional evenness and dispersion were greater in pastures than in the native forest. 5. Previous studies in humid forests showed the strong impact of cattle raising on dung beetle communities; however, the results of this study suggest that in dry forests ranching could have a low impact on native dung beetle diversity; however, reduced population abundance could result in impoverishment of dung beetle communities over time.