Increasing aridity reduces soil microbial diversity and abundance in global drylands

Artículo de publicación ISI

Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy similar to 41% of Earth ' s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and alpha-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands.

European Research Council (ERC) under European Community 242658 Spanish Ministry of Economy and Competitiveness BIOMOD Project CGL2013-44661-R Australian Research Council DP13010484 Salvador de Madariaga program of the Spanish Ministry of Education, Culture and Sports Grant PRX14/00225 Research Exchange Program of the Hawkesbury Institute for the Environment Alexander Von Humboldt Foundation Iniciativa Cientifica Milenio (MIDEPLAN) PO5-002 Comision Nacional de Investigacion Cientifica y Tecnologica PFB-23