Meta-analysis on the effect of biodiversity on tree transpiration

Tree species diversity can enhance forest productivity and resistance to climate extremes but can also increase transpiration rates, potentially exacerbating drought stress. A large variability in the effect of tree diversity on transpiration is found in the literature, and we conducted a meta-analysis to help better understand drivers of this variability. We computed effect sizes by comparing tree transpiration of mixed plots to monocultures from 31 studies. We calculated effect sizes at the species (comparison of trees of a given species in monoculture vs. mixed plots) and community (comparison of transpiration by all trees in monoculture vs. mixed plots) levels and assessed the influence of species richness, functional richness, water limitation (drought or regional aridity) and functional identity at the species level.