Trees with different mycorrhizal types show differential drought responses at the global scale

Abstract Climate drying is posing severe threats to forest ecosystems across the world. Although experimental evidence suggested that tree species with different mycorrhizal types may differ in their drought responses, a quantitative global synthesis is still lacking. By compiling and analyzing global datasets of four aspects of trees’ drought responses (i.e., mortality, sensitivity, growth reduction and growth recovery), we found that AM trees exhibited lower sensitivity to drought intensity variation than EM trees in the tropical zone, whereas the opposite was true in the temperate zone. In addition, growth and survival of EM trees were more strongly impacted by severe drought than AM trees in the temperate zone, potentially causing reduced EM dominance in some temperate regions under climate drying. Compared to other previously studied traits, mycorrhizal type is a better predictor of trees’ drought responses than specific leaf area, seed-bearing type, and rooting depth, but a worse predictor than wood density and maximum height. This study is the first to reveal the importance of mycorrhizal type in affecting trees’ drought responses at the global scale, contributing to a better understanding of the intraspecific differences in trees’ drought responses and the global biogeography of plant-mycorrhizal symbiosis.