Microbial responses to erosion-induced soil physico-chemical property changes in the hilly red soil region of southern China

• A high level of microbial biomass was observed in the depositional site.
• Water erosion provided greater impact on microbial biomass than community.
• Soil physico-chemical properties changes strongly impact bacterial community.
• Soil carbon availability was an important factor influencing bacterial community.

Water erosion can significantly alter soil physicochemical properties. However, little is known about soil microbial responses to erosion-induced soil physicochemical properties changes in the hilly red soil region of southern China. This research was conducted to determine the impact of water erosion on soil biological properties and the relationships between microbial community compositions and physico-chemical parameters. Soil samples of the 0–10 cm layer in one fallow depositional site and five erosional sites (including a Pinus massoniana Lamb. site, Elaeocarpus decipiens Hemsl. site, Michelia maudiae Dunn site, Cinnamomum bodinieri Levl. site and Lagerstroemia indica Linn. site) were collected. Denaturing gradient gel electrophoresis (DGGE) profiles of 16S rDNA were generated to describe the influence of soil erosion on bacterial communities. The results showed that the depositional site had greater microbial biomass and enzyme activities compared to most erosional sites. Redundancy analysis suggested that all physico-chemical parameters together accounted for 79.6% of the variation in bacterial community (P < 0.05). Among these parameters, dissolved organic carbon (DOC) showed a predominant effect on the variation (19.3%; P < 0.05), while soil organic carbon (SOC) and total nitrogen individually contributed to only 3% and 2.5% of the variance in bacterial community, respectively (P > 0.05). These results indicated that soil deposition is beneficial to enhance soil microbial biomass, while soil erosion is in reverse. DOC is a more important factor influencing soil biological characteristics in comparison to other measured physicochemical parameters. Relative to the quantity of SOC, the quality of C is more important in influencing soil biological properties.