Soil microbial communities influence plant-plant competition

Competition is a key process that determines plant community structure and dynamics, often mediated by nutrients and water availability. However, the role of soil microorganisms in plant competition, and the links between above- and belowground processes, are not well understood. Here we show that the effects of interspecific plant competition in plant performance are mediated by feedbacks between plants and soil microbial communities. Each plant species selects a singular community of soil microorganisms in its rhizosphere with a specific species composition, abundance and activity. When two plant species interact, the resulting soil microbial community matches that of the most competitive species, suggesting strong competitive interactions between soil microbial communities as well. We propose a novel mechanism by which changes in belowground microbial communities promoted by the most competitive plant species influence plant performance and competition outcome. These findings emphasise the strong links between plant and soil communities paving the way to a better understanding of plant community dynamics and the effects of soil microbial communities on ecosystem functioning and services.