Dung beetle communities change quickly following tropical forest restoration: A case study from southern Costa Rica

Active restoration of degraded forest ecosystems is a relatively new management technique that is increasingly applied worldwide to assist in the conservation of biodiversity, especially in the tropics. However, knowledge about its efficacy remains limited. The aim of this study was to assess early-stage success of actively restoring tropical forest using dung beetles (Coleoptera: Scarabaeinae) as bioindicators. To test the effectiveness of active restoration in the tropics, we designed and implemented a 20 ha experiment in the Osa Peninsula of Costa Rica. We tested three different active planting treatments, corresponding to high, medium, and low percentage planting of a fast-growing native tree (Ochroma pyramidale), a control treatment of natural regeneration, and reference data as an additional control from nearby old-growth forest. At each plot, dung beetle communities were surveyed three times since the restoration started and environmental variables were assessed to identify possible drivers of dung beetle community recovery. Our results showed that the dung beetle species and functional richness from restoration plots changed over time, and these communities became more similar to our old-growth forest control over the 5-year study duration. However, active restoration did not appear to accelerate the rate of dung beetle community recovery. Dung beetle community recovery was positively correlated with canopy height and negatively correlated with soil carbon-nitrogen ratio of restoration plots. Our results suggest that restoration efforts in the tropics can rapidly recover diverse communities with critical ecological functions, such as dung beetles – a key group representative of broader biodiversity recovery.