Invasive plants have stronger root recognition capabilities than native plants

Root-mediated conspecific recognition and avoidance could alleviate intraspecific competition and promote interspecific competitive abilities. This could result in communities dominated by few species. However, it remains unclear whether invasive plants, which frequently become dominant, possess higher capabilities of root recognition and segregation than natives. We compared root-recognition and segregation capabilities between five congeneric pairs of invasive and native plants using a split-root assay and an intraspecific root-distribution experiment. We also assessed the roles of soil microbial legacies in root-segregation capabilities. The split-root assay showed that invasive plants exhibited stronger root-recognition capacities than natives by reducing root allocation toward conspecifics. The intraspecific root-distribution experiment showed that both invasives and natives exhibited root segregation when grown on unconditioned soils. However, when grown on soils conditioned by either invasive or native plants, root segregation of natives disappeared, whereas invasives remained unaffected. Changes in root segregation of natives were associated with changes in the composition of soil fungal and bacterial communities. Invasive plants possess mechanisms of avoiding intensive intraspecific competition irrespective of soil microbial legacies, whereas for native plants, these mechanisms can be disrupted by soil microbial legacies. This could contribute to the competitive superiority of invasive plants.