The competitionbetween Bidens pilosa and Setaria viridis alterssoil microbial composition and soil ecological function

Bidens pilosa is recognized as one of the majorinvasive plants in China. Its invasionhas been associated with significant losses in agriculture, forestry,husbandry, and biodiversity. Soilecosystems play an important role in alien plant invasion. Microorganisms within the soil act asintermediaries between plants and soil ecological functions, playing a role inregulating soil enzyme activities and nutrient dynamics. Understanding the interactions betweeninvasive plants, soil microorganisms, and soil ecological processes is vitalfor managing and mitigating the impacts of invasive species on theenvironment. In this study, we conducteda systematic analysis focusing on B. pilosa and Setaria viridis,a common native companion plant in the invaded area. To simulate the invasion process of B. pilosa,we constructed homogeneous plots consisting of B. pilosa and S. viridis grown separately as monocultures, as well as inmixtures. The rhizosphere and bulk soilswere collected from the alien plant B. pilosa and the nativeplant S. viridis. Inorder to focus on the soil ecological functional mechanisms that contribute tothe successful invasion of B. pilosa, we analyzed theeffects of B. pilosa on the composition of soil microbialcommunities and soil ecological functions. The results showed that the biomass of B. pilosa increased by 27.51% and that of S. viridis was significantlyreduced by 66.56%. The organic mattercontents in the bulk and rhizosphere soils of B. pilosa wereapproximately 1.30 times those in the native plant soils. The TN and NO3– contents in the rhizosphere soil of B. pilosa were 1.30 to2.71 times those in the native plant soils. The activities of acid phosphatase, alkaline phosphatase, and urease inthe rhizosphere soil of B. pilosa were 1.98–2.25 timeshigher than in the native plant soils. Using high-throughput sequencing of the 16S rRNA gene, we found that B. pilosa altered the composition of the soil microbial community. Specifically, many genera in Actinobacteriaand Proteobacteria were enriched in B. pilosa soils. Further correlation analyses verified thatthese genera had significantly positive relationships with soil nutrients andenzyme activities. Plant biomass, soilpH, and the contents of organic matter, TN, NO3–, TP, AP,TK, and AK were the main factors affecting soil microbial communities. This study showed that the invasion of B. pilosa led to significant alterations in the composition of the soil microbialcommunities. These changes were closelylinked to modifications in plant traits as well as soil physical and chemicalproperties. Some microbial speciesrelated to C, N and P cycling were enriched in the soil invaded by B. pilosa. These findings provide additional support forthe hypothesis of soil-microbe feedback in the successful invasion of alienplants. They also offer insights intothe ecological mechanism by which soil microbes contribute to the successfulinvasion of B. pilosa. Overall, our research contributes to a better understanding of thecomplex interactions between invasive plants, soil microbial communities, andecosystem dynamics.