Microbial Composition and Activity of Natural, Restored, and Reclaimed Wetland Soils: a Case Study of Poyang Lake Basin, China

In this study, we employed pyrosequencing-based analysis of the V4-V6 16S rRNA gene region and community level physiological profiling (CLPP) to characterize and compare bacterial community composition and metabolic activities in order to determine if microbial composition and activity were able to recover in land transitioning from agriculture to natural wetland. The sample sites included natural wetland (with native vegetation), reclaimed for tillage (agriculture), and abandoned tilled (wetland restoration) soils. The entire data set comprised 78,790 good-quality sequences, 62,364 of which were classified in 23 known phyla. The dominant taxonomic groups presented in all samples were Proteobacteria (34.3%), Acidobacteria (15.5%), Verrucomicrobia (6.9%), Chloroflexi (6.3%), Nitrospira (2.6%) and Actinobacteria (2.4%), while 27.1% of the sequences could not be classified to any known phylum. Microbial community composition and activity were found to cluster into two distinct groupings: one associated with agriculture and the other with restored and natural wetlands. The average well colour development (AWCD) based on carbon source utilization pattern was significantly higher in natural and restored wetland soils than in reclaimed soils, suggesting an improvement of soil health. In conclusion, these findings indicated that microbial community composition and activity were affected by land use and may be used to assess the extent of recovery of natural microbial-driven processes during wetland restoration. Furthermore, restored soil microbial communities in this study appear to be tended to a gradual return to those of natural wetland soils with time.