The future of Southeast Asia's biodiversity: A crisis with a hopeful alternative

Southeast Asian countries, which encompass four global biodiversity hotspots, currently experience some of the highest rates of tropical deforestation in the world due to the expansion of oil palm and rubber plantations, logging, and urbanisation. Moreover, land-use change in Southeast Asia has been forecast to continue to expand alongside growing global demand for food, biofuels, and other natural-resource commodities, with potentially dire consequences for the region's diverse biota through habitat loss. Recent studies have forecast 21st century biodiversity loss in the Southeast Asian region using global projections of land-use change. However, these projections are too coarse to provide accurate predictions of biodiversity change at regional and biogeographic (i.e., biodiversity hotspot or national) scales, which are more relevant for effective policy planning and conservation interventions. Here we applied the reverse species-area-relationship (SAR) to regionally specified land-use scenarios, to predict the proportion of Southeast Asia's species (locally) committed to extinction by the year 2100. We project biodiversity outcomes ranging from best-case scenarios of stability or potential recovery of species through to a worst-case of additional losses (of up to 1.60 % of species lost). Whether species are lost or recovered depends on levels of future socio-economic development. In contrast to earlier work, we highlight that if sustainable development is pursued, not all is ‘doom and gloom’ for the region's diverse biota.