Belowground Secret for Aboveground Success: Fungi Drive Plant-Soil Interactions to Facilitate Plant Invasion

Biological invasions represent a fundamental threat to natural ecosystems, yet the drivers of invader dominance remain difficult to predict. While research has identified soil microbes and nutrient cycling as key influences on plant performance, it remains unclear how these belowground processes interact to catalyze and sustain invasions across space. Here we show that the invasion of Solanum rostratum across a 3,000 km transect in northern China is driven by a coordinated reorganization of soil fungal communities and nutrient dynamics. We find that invaded soils exhibit a distinct shift toward resource-acquisitive fungal assemblages, particularly arbuscular mycorrhizal fungi, concurrent with significant increases in soil nitrogen and organic carbon concentrations of 13–19%. These belowground changes generate strongly asymmetric plant–soil feedbacks: S. rostratum benefits from positive growth feedbacks in modified soils, whereas native species suffer reduced performance. Our results demonstrate a self-reinforcing feedback loop in which microbial restructuring enhances nutrient availability, favoring the invader at the expense of native competitors. These findings highlight the critical role of coupled microbial–biogeochemical processes in stabilizing plant invasions and suggest that ecosystem restoration strategies must address these persistent belowground legacies.