Reshaping of the soil microbiome by the expansion of invasive plants: shifts in structure, diversity, co-occurrence, niche breadth, and assembly processes

AimsUnderstanding the ecological impacts of biological invasions is a core issue of invasion ecology. Soil microbiomes control the functioning and health of ecosystems. The aim of this study was to uncover the changes in the soil microbiome caused by invasive plant expansion.MethodsTaking the typical invasive plant Alternanthera philoxeroides as an example, the structure, diversity, co-occurrence patterns, habitat niche breadth, and assembly processes of the microbiome in invasion-present and invasion-absent soils were analyzed based on high-throughput sequencing.ResultsThe invasion altered the structure and composition of the soil microbiome significantly. A group of biomarkers was established using the random-forest machine-learning model to best represent the differences in the microbiome between the invasion-present and invasion-absent soils. The plant invasion decreased the beta-diversity of the soil microbiome but increased the alpha-diversity. Compared with the invasion-absent soils, the invasion-present soils had a more complex and robust network with more keystone species, fewer modules, and more co-occurring associations. The microbiome in the invasion-present soils had a wider habitat niche breadth, with a higher proportion of habitat generalists and lower proportion of habitat specialists. Finally, the importance of stochasticity in the community assembly increased in the invasion-present soils, although deterministic processes still played a dominant role.ConclusionThis study reveals the consequences to the soil microbiome of the expansion of invasive plants, which is of great significance for an in-depth understanding of the ecological impacts of plant invasion and soil-microbe ecological processes.