Impacts of Soil Restoration on Microbial Communities at Three Gorges Reservoir and the Ningxia Yellow River Valley, China.

Understanding how restoration practices impact soil microbial communities is critically important if strategies for improving soil health are to be successful. A study was conducted to investigate microbial communities at restoration sites in both the Three Gorges Reservoir and the Ningxia Yellow River Valley of China. In both settings, microbial communities were more diverse and more abundant in restored sites than in the unrestored soils. In the re-vegetated hydro-fluctuation belt of the Three Gorges Reservoir (TGR) region, we characterized bacterial community diversity using the terminal-restriction fragment length polymorphism (T-RFLP) molecular method and compared soils in unvegetated sites, with tree and grass planted sites. Results showed that soil bacterial community diversity beneath tree plantations (e.g. pond /bald cypress) and grass-dominated soils (e.g Bermuda grass) was significantly higher than that of unplanted soil, however fungal community diversity indices showed no obvious differences. Revegetated soil microbial diversity was strongly related to soil chemical properties (e.g. nitrogen, phosphorus and organic matter) however, the microbial diversity of the unplanted soil had little relationship to soil chemistry.

In the Ningxia Yellow River Valley, different woody amendments were applied to improve sandy, low organic matter soils. Treatments included coarse wood chips incorporated into the top 20cm of soil (GBI), wood incorporation plus branch lattice for shade (GBI + B) and a surface mulch treatment (GBM). Four yrs post-amendment, through high-throughput pyrosequencing of the 16S rDNA gene, we found that the phyla Proteobacteria, Acidobacteria, Actinobacteria, and Planctomycetes predominated in all the soil samples, but with variations in relative abundance among treatments. Overall microbial diversity was low and physical properties and microbial characteristics differed significantly among treatments. Both the artificial plantations and soil amendments may provide material and energy sources to encourage microbes in the degraded soils. We conclude that restoration practices have a significant impact on soil microbial communities but resulting communities differ greatly.