Root-microbe-soil coupling enhances rhizosphere priming and nitrogen acquisition in invasive plants

Abstract The ecological success of invasive plants is often associated with enhanced nutrient acquisition, but the underlying root–microbe–soil interactions remain poorly resolved. We conducted a dual-isotope (13C and 15N) microcosm experiment using three congeneric pairs of invasive and native plants to quantify rhizosphere priming effect (RPE), nitrogen uptake, and root–microbe–soil coordination. Invasive plants consistently displayed larger root systems, higher biomass accumulation, enhanced ammonium (NH4+) uptake rates and N use efficiency compared to native congeners. These traits were associated with increased microbial biomass and elevated extracellular activities targeting C-, N-, and phosphorus-acquisition (i.e., β-glucosidase, β-N-Acetylglucosaminidase, acid phosphatase) and stronger RPE, especially during early growth stages. Structural equation modeling revealed tighter coupling between root traits, microbial enzyme activity, and nutrient acquisition in invasive species, indicating a more integrated and efficient belowground interactions. Invasive species showed enhanced root biomass, microbial enzyme activity, and nutrient use efficiency, forming tightly coupled rhizosphere integration that strengthened RPE and nutrient cycling. These findings demonstrate that invasive plants promote coordinated root-microbe-soil interactions to enhance nutrient cycling and decomposition processes, thereby conferring a competitive advantage. Our findings highlight belowground interaction as a key driver of invasion success, offering a novel systems-level perspective in invasion ecology.