Linking rhizospheric microbiota and metabolite interactions with harvested aboveground carbon and soil carbon of lakeshore reed wetlands in a subtropical region

Lakeshore wetlands are global carbon (C) hotspots, but their role in C sequestration has been largely overlooked. The rhizosphere has a complex interaction of microbiota and metabolites, which plays an important role in wetland C cycling. This study aims to understand how the rhizospheric interactions affect harvested aboveground C and soil C of lakeshore wetlands in a subtropical region.

An investigation of five lakeshore reed (Phragmites australis) wetlands at the similar latitudes of the Lower Yangtse Valley in China was carried out to explore the relationship of rhizospheric interactions with harvested aboveground C and soil C. The plant traits and soil physicochemical properties were determined due to their important role in affecting rhizosphere interactions.

Plant traits and soil physicochemical properties significantly differed among the sites, while aboveground C fixation did not significantly differ. The soil organic C (SOC) content of the topsoil was accounting for the majority of the soil total C at most sites, except for the wetland at the Yangtze River estuary with higher soil pH and conductivity, whose soil inorganic C (SIC) accounted for almost half. Bacterial community and metabolite composition were significantly partitioned across the region. Structural equation modeling revealed the rhizospheric interactions positively affected aboveground C and SOC, but negatively affected SIC. Their effects on soil C content were stronger than those on aboveground C fixation.

The rhizosphere exhibited the direct and indirect effects on harvested aboveground C and soil C by altering microbial community structure and metabolite composition.