Canopy cover is a key factor to preserve the ecological functions of dung beetles in the southern Atlantic Forest

Abstract

In general, livestock activities affect the diversity and ecological functions of dung beetles. However, some practices associated with tree retention could reduce this problem while maintaining productivity. The objective of this study was to explore the influence of canopy cover on dung beetle biomass, their burial activity and changes in soil conditions associated with this activity, in the southern Atlantic Forest of Argentina. Four habitat types were compared: (i) native forest, (ii) silvopastoral systems with native trees, (iii) silvopastoral systems with exotic trees (Pinus taeda), and (iv) open pastures. Canopy cover, and microclimatic and soil conditions were also evaluated in each habitat type. The native forest and silvopastoral systems (both native and exotic) showed lower temperatures, higher relative humidity, higher electrical conductivity, and higher nitrate (N-NO3) and sand contents than open pastures, which showed opposite microclimatic conditions and higher clay contents. In addition, field experiments using acrylic plastic beads and cow dung were performed to evaluate the burial activity of dung beetles, and its influence on soil properties. Soil samples were collected after 30 days to compare the soil conditions among habitat types. Total burial (>95%) and depth (5?6 cm) of acrylic plastic beads were higher in habitat types with native trees than in livestock systems with exotic trees and open pastures; moreover, dung beetle total biomass was strongly and linearly related to burial activity among habitat types. We observed no direct influence of burial activity on soil properties. Our results support the idea that livestock systems with native trees improve the environmental parameters, biomass and ecological functions of dung beetles compared with silvopastoral systems with exotic trees and open pastures.