Impacts of land use change on South-east Asian forest butterflies: a review.
South-east Asia has the highest relative rate of habitat loss and degradation in the humid tropics. The responses of less 'charismatic' groups, including butterflies, to habitat disturbance remain relatively poorly understood. Many South-east Asian butterflies are endemic to the region and face global extinction if current levels of deforestation were to continue. Here, I highlight South-east Asia as a region urgently in need of butterfly conservation research and review empirical studies of the responses of South-east Asian butterflies to land use change. Additionally, I discuss some methodological pitfalls for such studies. Furthermore, I argue for the importance of identifying the ecological correlates of sensitivity of butterfly species to forest modification and the potential biological mechanisms underlying their responses to land use change. There has been no consensus among previous studies on the effects of land use change on butterfly communities in South-east Asia. Of the 20 studies I reviewed, seven reported higher species richness/diversity in undisturbed (or the least disturbed) forest than in disturbed habitats, nine reported the opposite trend, three reported no difference and one reported a strong influence of seasonality on the impacts of logging. Some of these studies may contain inherent methodological biases resulting from the failure to control for sampling effects, the lack of consideration for the spatial scale of analysis and incomplete sampling of the vertical strata in tropical rainforests. Synthesis and applications. Empirical studies of the effects of land use change on tropical forest insects are sorely lacking from South-east Asia. Butterflies are an ideal taxonomic group for such investigations. Future studies should be designed carefully to avoid the methodological pitfalls highlighted here. Determining the ecological correlates of sensitivity of butterflies to forest modification is important for the pre-emptive identification of species of conservation concern and for generating testable hypotheses on the differential responses of species to forest modification. Experimental studies are needed to determine the mechanisms underlying the responses of species to land use change in order to develop effective strategies for the conservation of butterflies in human disturbed landscapes.