Soil legacies of genotypic diversity enhance population resistance to water stress

While thepositive relationship between plant diversity and ecosystem functioning is frequently observed and often attributed to direct plant-plant interactions, it remains unclear whether and how the effects of plant diversity endure through soil legacy effects, particularly at thelevel of genotypic diversity.We manipulated the genotypic diversity of <i>Scirpus mariqueter</i>and tested its soil legacy effects on aconspecific phytometer under low- and high-water availabilityconditions. We found that genotypic diversity enhancedphytometer productivity through soil legacies, with stronger effects under low-water availability conditions, improving itsresistanceto water stress. Moreover, this effect was attributed to the association of asexual and sexual reproductive strategies by increasingramet number to ensure plant survival under low-water availabilityand promotingsexual reproduction to escape stress.The observed diversity effects were primarily associated with increased levels of microbial biomass in soils trained by populations with diverse genotypes. Our findings highlight the importance of plant genotypic diversity in modulating ecosystem functioning through soil legacies, and call for management measures that promote genetic diversity to make ecosystems sustainable in the face of climate change.