Diversity affects microclimate temperature and humidity: an overview of the evidence and major unanswered questions

Climate change is increasing global temperatures, increasing atmospheric drying, and driving more severe and frequent drought. Plants can cool and humidify microclimates through sensible and latent heat exchange. Higher diversity plant communities can modify microclimates more strongly than lower diversity plant communities, creating the potential for strong biodiversity-climate feedbacks. Here, we review the physical and physiological mechanisms that drive these diversity-microclimate patterns, catalogue the magnitude of these trends across ecosystem types, and explore how microclimate feedbacks can explain the relationship between biodiversity and ecosystem functioning. We identify key areas where more research is needed (e.g. the role of belowground traits that drive latent heat exchange). This research is essential for understanding how biodiversity and climate are linked at micro- and macroscales.