Significant Association Between Soil Dissolved Organic Matter And Soil Microbial Communities Following Vegetation Restoration In The Loess Plateau

Dissolved Organic Matter (DOM) affects the fundamental biogeochemical processes in soil including circulation and distribution of carbon and nutrients. Likewise, soils are hotspots of microbial diversity, supporting their ability to provide key soil functions and ecosystem services. Detailed understanding of the interaction between DOM chemical diversity and soil microbial community is essential to predict the direction of C in soil after vegetation restoration. In this study we have characterized the chemical diversity of soil DOM, evaluated the associated changes of the soil microbial community composition and determined the specific relationship between DOM and microbial community composition. The results indicated that the unsaturated degree, obstinacy, oxidation degree, and average molecular mass of soil DOM increased with the duration of vegetation restoration. DOM with low double-bond equivalents (DBE) was less stable and was more likely to undergo transformation reactions to produce persistent organic materials with high carbon and high double-bond equivalents. The relative abundance of soil bacteria and fungi showed different trends in response to vegetation restoration efforts which may be related to the change of soil chemical composition as suggested by redundancy analysis. In addition, network analysis identified complex connectivity and strong interaction between the soil microbial community and DOM. Overall, this study has important guiding and prediction significance for the relationship between DOM and soil microbial community during vegetation restoration. Moreover, it provides a theoretical basis for the quantitative evaluation of the ecological restoration effect to alleviate soil and water loss on the Loess Plateau.