Mimicking a rainfall gradient to test the role of soil microbiota for mediating plant species responses to drier conditions

Plant interactions with soil microbiota are important drivers of biodiversity and ecosystem function, but climate change can modify these interactions by directly altering the soil community, which can affect the direction and magnitude of such interactions. We manipulated water quantity and soil microbiota of two populations of three plant species that differ in their interactions with soil microbiota and assessed germination and biomass production under conditions that mimicked a rainfall gradient in SE Spain. We assessed the importance of soil microbiota from home and away (drier) sites for alleviating or exacerbating the effects of drier conditions. Our results suggest that home soil microbiota enhanced germination of the legume Trifolium stellatum. Conversely, we found that the grass, Lagurus ovatus, and the forb, Sisymbrium erysimoides, produced more biomass under moderate drying with soil microbiota from a drier site than with home soil microbiota, suggesting that dry-adapted soi...