Background and aims In 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.Methods We 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.Results Soil microbial biomass carbon (MBC) and nitrogen (MBN), total PLFAs, and alpha diversity increased signi cantly 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, signi cantly decreased with succession; the opposite was true for Acidobacteria, Planctomycetes, Gemmatimonadetes Deltaproteobacteria and Gammaproteobacteria. However, the proportion of fungi did not signi cantly 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 ndings advance the current understanding of sand-stabilizing plant-soil interactions during natural restoration and the reversal of deserti cation in stressful desert ecosystems.
The alpine sandy dune ecosystem is highly vulnerable to global climate change. Ecological stoichiometry in plants and soils plays a crucial role in biogeochemical cycles, energy flow and functioning in ecosystems. The alpine sandy dune ecosystem is highly vulnerable to global climate change. However, the stoichiometric changes and correlations of plants and soils among different types of sandy dunes have not been fully explored. Three sandy dune types (moving dune, MD; semifixed dune, SFD; and fixed dune, FD) of the Sophora moorcroftiana shrub in the middle reaches of the Yarlung Zangbo River were used as the subjects in the current study. Plant community characteristics, soil physicochemical properties, carbon (C), nitrogen (N), and phosphorus (P) contents of leaves, understorey herbs, litter, and soil microbes were evaluated to explore the C:N:P stoichiometry and its driving factors. Sandy dune type significant affected on the C:N:P stoichiometry in plants and soils. High soil N:P ratio was observed in FD and high plant C:P and N:P ratios in SFD and MD. The C:N ratio decreased with sand dune stabilization compared with other stoichiometric ratios of soil resources. Leaf C:P and N:P ratios in S. moorcroftiana were higher than those in the understorey herb biomass, because of the low P concentrations in leaves. C, N and P contents and stoichiometry of leaves, understorey herbs, litter and microbe were significantly correlated with the soil C, N and P contents and stoichiometry, with a higher correlation for soil N:P ratio. P was the mainly limiting factor for the growth of S. moorcroftiana population in the study area and its demand became increasingly critical with the increase in shrub age. The variation in the C:N:P stoichiometry in plants and soils was mainly modulated by the soil physicochemical properties, mainly for soil moisture, pH, available P and dissolved organic C. These findings provide key information on the nutrient stoichiometry patterns, element distribution and utilization strategies of C, N and P and as well as scrubland restoration and management in alpine valley sand ecosystems.
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