Land use change drives major loss of Southeast Asian biodiversity

Southeast Asia is highly biodiverse and currently experiences among the highest rates of tropical deforestation globally, but impacts on biodiversity are not well synthesized. We use Bayesian multi-level modeling to meta-analyse 831 pairwise comparisons of biodiversity in sites subject to human land use change and anthropogenic forest disturbance (for example in plantations or logged forest) versus undisturbed sites. After controlling for hierarchical dependences, we show that biodiversity is a fifth lower in sites with these land-use changes (95% credible interval= 16-28%, mean = 22%). This reduction was greater when land use change/anthropogenic forest disturbances were high-intensity (34% reduction in biodiversity) compared to low-intensity (18% reduction), and effects were consistent across biogeographic regions and taxa. Oil-palm plantations lead to the greatest reduction in biodiversity (39%, CI 27-48%), and agroforests the least (24%, CI 10-37%). We also find that biodiversity is reduced in young secondary forest by 26% (CI 4-42%) compared to undisturbed forest, but there is no reduction in biodiversity for intermediate or mature-aged secondary forest (although species composition is potentially altered). Overall, our study provides the clearest evidence yet of the substantial detrimental impact of land-use change and anthropogenic forest disturbance on the biodiversity of Southeast Asia.