Responses of tropical forest herpetofauna to moderate anthropogenic disturbance and effects of natural habitat variation in Sulawesi, Indonesia

Tropical forest destruction is a major contributor to global biodiversity loss, with much of remaining forests subject to extensive subsistence use. Compared to forest clear-felling and conversion, the impacts of these less intense but complex disturbance regimes on biodiversity remain poorly understood. Given the challenges of protecting pristine tropical forests for conservation in developing regions, there is a strong imperative to understand the role of altered forests with a range of low to moderate disturbance regimes in long term biodiversity conservation. We sampled tropical rainforest reptile and amphibian diversity over a nine year period along a gradient of moderate anthropogenic disturbance to intact primary rainforest in Sulawesi, Indonesia. We evaluated the relative influences of anthropogenic disturbance proxies and natural habitat variability on species richness and assemblage composition. Reptile and amphibian species richness were affected by natural variability in a range of habitat characteristics, but not by moderate anthropogenic disturbance. In contrast, species composition varied with both natural and anthropogenic disturbance metrics. Our results indicate that even low to moderate levels of anthropogenic disturbance have measurable, pervasive, impacts on tropical herpetofaunal diversity. However, moderately disturbed and altered forests that retain relatively high canopy cover and habitat complexity still retained most species associated with primary forest, indicating that they provide a significant contribution to herpetofaunal biodiversity conservation. Management implications from these findings complement those for birds and large mammals in tropical Asia, in that sustainable biodiversity conservation is likely to be best achieved by maintaining larger forest areas of variable disturbance and usage regimes around more remote, minimally disturbed core areas.