The Future of Forest Microclimate in Southeast Asia

Abstract Forest microclimates regulate biodiversity, ecosystem functioning, and species' thermal tolerance, yet tropical forest disturbances (logging, fire and fragmentation) increasingly disrupt these conditions. Southeast Asia, home to 15% of the world's tropical forests, faces rapid deforestation and degradation, but large‐scale changes in maximum microclimate temperature (Tmicro max ) remain poorly quantified. Here, we estimated baseline average Tmicro max (1984–2014), measured 15 cm above the surface and projected changes by 2050 under different scenarios combining climate forcing and forest cover change. Baseline Tmicro max ranged from 11.6°C to 25.1°C, driven mainly by topography, macroclimate, and vegetation structure. Projections indicate regional mean increases of 1.4°C (SSP2‐4.5) to 2.1°C (SSP5‐8.5). By 2050%, 52%–66% of forests may experience Tmicro max values warmer than any in the baseline period on average with Brunei, Indonesia, and Malaysia showing the strongest changes. These results reveal substantial sub‐canopy warming, posing potential risks for tropical biodiversity and highlighting the need for spatially informed conservation planning.