Synergistic Impact of Complex Topography and Climate Variability on the Loss of Microclimate Heterogeneity in Southeast Asia

Microclimate heterogeneity in Southeast Asia and its implications for biodiversity remain understudied. We investigated microclimate changes between 1982 and 2017 using high-resolution data and a patch-mosaic model. Our findings reveal a decline in microclimate heterogeneity (as indicated by Shannon's diversity index) and a significant increase in elevation. Topographical factors (similar to 50.6%) and climatic factors (similar to 21.5%) primarily influenced the decline. Spatial heterogeneity weakened with larger moving windows and coarser grid-scale data sets. Our study suggests that shifting mountainous microclimates play a crucial role in mediating biodiversity in Southeast Asia. Plain Language Summary In response to climate change, research on microclimates with potential ecological significance has become increasingly popular. Despite Southeast Asia being an exceptionally rich area for biodiversity, only a limited number of studies have been conducted to explore the intricate heterogeneity of fine-scale microclimates in this region. Furthermore, the impact of potential environmental driving forces on this heterogeneity remains scarcely explored. Within this study, we used high-resolution data sets and adopted a "patch-mosaic" model paradigm to examine changes in microclimate heterogeneity, quantified by Shannon's diversity index (SHDI), across Southeast Asia from 1982 to 2017. Our findings unveil a discernible reduction in SHDI between the periods 1982-1999 and 2000-2017, concomitant with a marked elevation increase. Deconstructing the attribution analysis within 39 mountainous areas revealed that topographical factors (similar to 50.6%) and climatic factors (similar to 21.5%) were the foremost influences underpinning declines in SHDI within these mountainous areas. We also found that the spatial heterogeneity of the microclimates weakened as the moving window size increased and the grid-scale data set became coarser. We suggest that biodiversity in Southeast Asia is likely mediated by shifting mountainous microclimates.