Southeast Asia experiences one of the highest rates of deforestation in the tropics due to agricultural
expansion, logging, habitat fragmentation and urbanization, which are expected to result in species
declines and extinctions. In particular, growing global demands for food, biofuel and other commodities
are driving the rapid expansion of oil palm and paper-and-pulp industries at the expense of lowland dipterocarp
forests, further jeopardizing Southeast Asian forest biotas. We synthesize recent findings on the
effects of land-use changes on plants, invertebrates, vertebrates and ecosystem functioning/services in
Southeast Asia. We find that species richness and abundance/density of forest-dependent taxa generally
declined in disturbed compared to mature forests. Species with restricted ranges and those with habitat
and foraging specialization were particularly vulnerable. Forest loss also disrupted vital ecosystem services
(e.g. crop pollination). Long-term studies are needed to understand biotic sustainability in regenerating
and degraded forests, particularly in the context of the synergistic or additive effects of multiple
agents of biodiversity loss (e.g. invasive species and climate change). The preservation of large tracts of
mature forests should remain the principal conservation strategy in the tropics. In addition, reforestation
and reintroductions of native species, as well as improved connectivity among forest patches could
enhance the conservation value of forest remnants in human-dominated landscapes.