Erosion and deposition divergently affect the structure of soil bacterial communities and functionality

Soil erosion and deposition dramatically affect the biogeochemical cycle of terrestrial ecosystem, while how the microbial communities and soil multiple functions responds to soil erosion, particularly following deposition, are rarely addressed. Such knowledge gap hinders our comprehensively understanding about biogeochemistry cycling, the development of sustainable soil management practices and the restoration of degraded lands in an eroding environment. Herein, we compared the bacterial communities in the eroding, depositional, and adjacent non-eroding forest zones in the China's Loess Plateau to explore how erosion and deposition alter soil bacterial communities and multifunctionality. We used the 16S rRNA gene amplicon sequencing to assess bacterial richness and community composition and analyzed co-occurrence networks to elucidate the associations among microbes. We also measured a series of soil functional parameters to assess soil multifunctionality and analyzed the relationship between soil multifunctionality and bacterial community structures. While erosion significantly reduced soil bacterial richness and multifunctionality, much of this loss was recovered in the depositional zone, with greater values in depositional zone than eroding zone. Soil erosion and subsequent deposition significantly decreased the complexity and connectivity of bacterial co-occurrence network compared with the forest. Soil multifunctionality was regulated by bacterial richness, community compositions and network complexity. Random forest modeling showed specific ecological clusters were the optimal predictors of multifunctionality, which was positively affected by Acidobacteria dominated network module but negatively affected by Actinobacteria dominated network module. This study suggests deposition can alleviate negative impacts of erosion on bacterial community richness and soil multifunctionality, and thus would be helpful for developing sustainable soil management and restoring degraded lands in eroding environments.