Plants and Seasons Influence Sediment Organic Carbon Through Their Effects on Microbes in Two Types of Wetlands

As vital carbon pools within terrestrial ecosystems, wetlands store sediment organic carbon (SOC), a process influenced by plant communities, seasonal variations, and wetland types. Microbial communities, fundamental to wetland ecosystems, are hypothesized to regulate carbon storage. We investigated sediment microbial communities and carbon storage in different seasonal and plant conditions in two types of wetlands. Sediment organic carbon, the associated environmental factors, and microbial community characteristics were detected to explore the impacts of seasons and plants on SOC. Plants and seasons significantly influenced the content of SOC in constructed wetland, while only altered the content of dissolved organic carbon (DOC) in river wetland. In river wetland, plants increased the microbial function of Amino Acid Metabolism through the input of exogenous dissolved organic carbon (DOC) and the effect on moisture content. The functional traits of Carbohydrate Metabolism in sediment were higher in river wetland than that in constructed wetland. Our results indicated that plants and seasons influenced SOC in wetlands through their effects on sediment microbial community and function. Compared with the river wetland, the constructed wetland had more stable microbial communities and might be easier to fix organic carbon from plants. This study highlights the importance of the carbon sequestration potential of constructed wetlands due to the stable microbial communities.