Evaporative stress, represented by a vapor pressure deficit (VPD) is a key driver of plant ecology in terrestrial biomes. In this study, we disentangled the processes controlling VPD variability across a topographically diverse landscape, explored VPD role in bryophyte community assembly, and separated VPD effects from correlated maximum air temperature. We found that microclimate temperature-driven VPD controls community composition and richness of bryophyte assemblages in temperate forests.