Microbial and Edaphic Responses to Invasion by Ageratina adenophora: Implications for Ecosystem Management

Ageratina adenophora is one of the most invasive and ecologically destructive plant species in southwestern China. Although its above-ground competitive strategies have been widely studied, less is known about how it alters below-ground soil processes and microbial communities that may in turn facilitate its spread. This study integrates both rhizosphere and non-rhizosphere soils and applies co-occurrence network analysis to characterize microbial responses to A. adenophora invasion. To assess the impact of A. adenophora on soil ecology, we compared soil physicochemical properties and bacterial communities between invaded and non-invading sites. Using 16S rRNA high-throughput sequencing and bioinformatic network analysis, we evaluated changes in microbial composition, abundance and interactions under invasion conditions. The soil moisture content was significantly reduced in areas populated with A. adenophora, especially in rC (58.84%) and nrC (65.55%), while the concentrations of NO₃ ^--N (especially in nrB, 221.52%) and NH₄ ⁺-N (especially in rD, 736.88%) were significantly elevated. The structure of the microbial community shifted markedly, with soil moisture and NH₄ ⁺-N identified as dominant factors shaping bacterial assemblages. Microorganisms that are significantly affected include Proteobacteria, Actinobacterota, and Acidobacteriota. These changes are likely to create favorable feedbacks that enhance A. adenophora's invasive success. Our findings reveal that A. adenophora not only competes above ground, but also modifies soil conditions and microbial networks to reinforce its invasion. By integrating rhizosphere-non-rhizosphere comparisons with microbial network analysis, this study provides a more detailed understanding of how A. adenophora alters soil microbial communities. These results emphasize the need to integrate soil microbial dynamics and nutrient feedbacks into the management of invasive species. Restoration strategies that regulate soil nitrogen levels and moisture may help suppress invader dominance and restore ecosystem function.