Impact of oil palm agriculture on understory amphibians and reptiles: A Mesoamerican perspective

Oil palm plantations expand rapidly in tropical regions, including the Neotropics. This study, quantifies the impact on the herpetofauna of the Pacific lowlands of Costa Rica. Amphibians and reptiles were sampled along transects in forest interior (FI), at forest margins (FM) and in oil palm plantations (OP). While no significant difference in species richness was found between FI and FM, OP were characterized by a strongly impoverished fauna. Total species richness of amphibians and reptiles was reduced to 45.3% and 49.8% compared to FI, respectively. Species assemblages in OP differed from forest habitats and were characterized by disturbance-tolerant species and a severe loss of endemic species. In amphibians, functional diversity declined dramatically towards OP indicating a decrease of their ecological function. The almost complete absence of leaf litter, understory vegetation and woody debris and the more open canopy may be responsible for the depauperate herpetofauna in OP. Enhancing understory vegetation could help making plantations a less hostile environment for some species. Still, those management measures might not be enough to promote forest specialists. Therefore, to maintain a diverse herpetofauna in tropical human-modified landscapes, the protection of any forested habitats such as secondary forests and strips of gallery forests is essential.