Iron-bound organic carbon is conserved in the rhizosphere soil of freshwater wetlands

The greater number and activity of microorganisms in the rhizosphere than bulk soils is expected to affect iron (Fe) and carbon (C) biogeochemical cycling. We investigated the coupled relationships among Fe, C, and Fe-reducing bacteria (FeRB) in the rhizosphere and bulk soils of Calamagrostis angustifolia and Carex lasiocarpa in a freshwater wetland of international importance (i.e. Ramsar site) in Northeast China. Nonmetric multi-dimensional scaling analysis showed distinct clusters of FeRB in the ordination space of C. angustifolia and C. lasiocarpa associated with the rhizosphere (R = 0.707, p = 0.002 and R = 0.830, p = 0.004, respectively). The relative abundance of FeRB was significantly (p