Plant–plant and plant–soil interactions under drought and the presence of invasive buffelgrass (Cenchrus ciliaris)

Soil microbiomes could mediate plant responses to interacting environmental changes such as drought and plant invasion. We used a greenhouse experiment to assess changes in soil bacterial/archaeal and fungal communities, and competition between buffelgrass (Cenchrus ciliaris; an African perennial C4 bunchgrass introduced in the Sonoran Desert) and two native Sonoran Desert plants (i.e., Aristida purpurea and Plantago patagonica) under experimental drought. We found that buffelgrass benefitted from growing in the vicinity of native plants, particularly in drier conditions, and that this effect might be mediated by higher bacterial richness and an increased proportion of putative nitrogen-fixing bacteria in surrounding soil. Overall, plant–soil interactions are key to understand the interactive effects of abiotic and biotic stressors, and thus, critical to the management and restoration of invaded ecosystems.