Differences in soil microbial communities with successional stage depend on vegetation coverage and soil substrates in alpine desert shrublands

Background and aimsIn semiarid ecosystems, changes in plant communities are promoted under shrub canopies during restoration, but the link between shrub community restoration dynamics and changes in soil microbe communities is still unclear.MethodsWe characterized the community structure and plant interactions of soil microbes by combining different methodological approaches (including high-throughput sequencing of the 16S rRNA gene and ITS gene, analysis of phospholipid fatty acids (PLFAs) and chloroform fumigation) and the key driving factors along a successional gradient of Sophora moorcroftiana shrub community in the middle reaches of the Yarlung Zangbo River.ResultsSoil microbial biomass carbon (MBC) and nitrogen (MBN), total PLFAs, and alpha diversity increased significantly as the successional stage advanced, and MBC and MBN were positively correlated with the carbon and nitrogen contents in the soil. Mantel test showed that successional stage-induced changes in soil microbial beta diversity were mainly associated with shrub coverage and soil physicochemical properties. The relative abundances of bacterial PLFAs, particularly those of gram-negative bacteria, such as Bacteroidetes, Alphaproteobacteria and Betaproteobacteria, significantly decreased with succession; the opposite was true for Acidobacteria, Planctomycetes, Gemmatimonadetes Deltaproteobacteria and Gammaproteobacteria. However, the proportion of fungi did not significantly differ among the four successional stages; the dominant phyla were Ascomycota and Basidiomycota. ConclusionWe suggest that shrubs directly shape soil microbial communities or indirectly affect such communities by altering soil substrates. Our findings advance the current understanding of sand-stabilizing plant-soil interactions during natural restoration and the reversal of desertification in stressful desert ecosystems.