Mikania micrantha invasion enhances the carbon (C) transfer from plant to soil and mediates the soil C utilization through altering microbial community.

Exotic plant invasion alters the structure and coverage of terrestrial vegetation and affects the carbon (C) stocks in ecosystems. Previous studies have shown the increases in the C stocks with increasing invasive plants, but these results remain contentious. Soil microbial communities are usually altered by plant invasion, which potentially influences the C cycling underground. We hypothesized that the plant invasion-caused dynamic changes in soil microbes would lead to the corresponding change in soil C accumulation. Using greenhouse experiments we simulated different invader intensities through varying the relative abundance of invasive species Mikania micrantha and its co-occurring native species Paederia scandens. By analyzing 13C-phospholipid fatty acid we found the invasive M. micrantha assimilated more 13C and transferred faster the fixed 13C through different tissues to soils, as compared to native P. scandens. Soil microbial components, i.e., i15:0, 16:0, 10Me16:0, 18:1w9c and 18:2w6,9 were mainly using the photo-assimilated 13C. In addition, we found a hump-shaped relationship between soil net 13C accumulate rate and rhizosphere microbial biomass, indicating that the soil C accumulation may be either enhanced or reduced in invaded ecosystems, depending on microbe abundance.