Conservation of amphibians in Borneo: Relative value of secondary tropical forest and non-forest habitats

Abstract

The impact of degradation of Southeast Asian rainforests and conversion to oil palm plantations on amphibians is unknown. To assess the relative value of secondary forests, oil palm plantations and other non-forest habitats for amphibian conservation, we evaluated amphibian species richness and assemblage composition in secondary lowland forests, compared with oil palm plantations and other non-forest habitats, along the Lower Kinabatangan River, eastern Sabah, Malaysia. Secondary forests retained a large proportion of amphibian species known from lowland primary rainforests. Species richness was higher in secondary forest habitats compared to oil palm plantations and other non-forest habitats. Secondary forests retained a much higher proportion of endemic species than non-forest habitats. We found strong differentiation between the frog assemblages in forest, non-forest and plantation sites. Oil palm plantations retained no microhylid species, few arboreal species and were dominated by habitat generalist and human commensal species. Our findings suggest that, despite a history of disturbance and degradation, remnant secondary forests may play an important role in conserving lowland amphibian diversity. In contrast, oil palm plantations have comparatively low conservation value for amphibians. Our study highlights the value of setting aside adequate areas of representative forest habitats within agricultural landscapes in order to conserve biodiversity, even when those remnants have a history of prior disturbance.