Selective logging effects on ‘brown world' faecal-detritus pathway in tropical forests: A case study from Amazonia using dung beetles

While a significant effort has been made to understand how human activities influence biodiversity, less attention has been given to the consequences of tropical forest disturbance on belowground functional processes and its linkages with environmental drivers. Here, we demonstrate how selective logging influenced dung beetle communities and two associated ecological processes – namely, dung consumption and incidental soil bioturbation – in the eastern Brazilian Amazon, using a robust before-and-after control-impact design. We tested hypotheses about logging-induced changes on environmental condition (canopy cover, leaf litter and soil texture), community metrics (e.g. dung beetle species richness and biomass) and beetle-mediated faecal-detritus processing; and on the importance of the environment for beetle communities and functional processes. We show that post-logging changes in canopy openness do not necessarily mediate logging impacts on dung beetle diversity and biomass, which were directly influenced by reduced impact logging (RIL) operations. Although neither environmental condition (leaf litter or soil sand content) nor faecal consumption and incidental soil bioturbation were directly affected by RIL, the relationships between environmental condition and biological components were. By showing that selective logging alters the linkages among belowground ecological processes and environmental drivers, we provide support that logged forests can retain some important functioning processes, in particular faecal consumption, even when the dung beetle diversity and biomass are impoverished. These results provide support for the resistance of functional processes to logging-induced changes in biodiversity.