Linkage of soil organic matter composition and soil bacterial community structure as influenced by dominant plants and hydrological fluctuation in Poyang Lake

We evaluated the role of water levels and plant-associated effects on the composition of bacterial communities and the soil organic matter (SOM) composition in wetland ecosystem. Soil (0–15 cm) associated with Phragmites communis, Triarrhena lutarioriparia, Carex cinerascens, and Zizania latifolia was sampled in different water levels (as proxied by sampling time) to analyze soil SOM composition via diffuse reflectance infrared Fourier transform spectroscopy in the mid-infrared range analysis and to analyze soil bacterial communities by high-throughput 16S rRNA gene sequencing. Soil dominant SOM composition (1623–1635 cm−1 and 3444–2697 cm−1) were obviously influenced by water levels not plant species (p < 0.05). Proteobacteria, Chloroflexi, Acidobacteria, and Firmicutes were the most abundant phyla and exhibited significantly different distributions across the soils with Z. latifolia, P. communis, T. lutarioriparia, and C. cinerascens communities and the non-plant flat mud soil (p < 0.05). Redundancy analysis and variation partitioning analysis indicated that the Wc, active organic carbon, TCstem, Temsoil, and water level significantly influenced the dominant soil bacterial taxonomic composition, while the soil bacteria may influence the SOM composition. These findings suggested that soil SOM composition and bacterial communities were strongly affected by plant species and water levels. This study provides an in-depth insight into how specific SOM components related to the different distributions of the specific bacterial taxonomic groups that are responsible for key ecological functions in wetland ecosystem soils.