Community composition and catabolic functional diversity of soil microbes affected by Hedysarum scoparium in arid desert regions of northwest China

Abstract

The soil microbial community and edaphic factors in the rhizosphere and bulk soils of Hedysarum scoparium were investigated at seven arid desert locations in northwest China in July 2016. Plant and edaphic factors had significant effects on the community composition and functional diversity of soil microbes. Bacteria (ranging from 2.57 to 4.23 nmol g−1) contributed the most to the microbial community composition, followed by actinomycetes, followed by fungi. Carbohydrates, polymers, and carboxylic acids were the main carbon sources for soil microorganisms. Principal component analysis showed that the carbon source catabolism of soil microorganisms was higher in the rhizosphere than in bulk soils. Spearman correlation analyses revealed that the content of Gram-negative bacteria was significantly negatively correlated with the amino acids and that the content of AM fungi was significantly positively correlated with the carbohydrates and amines. Soil organic carbon, pH, and ammoniacal-N were significant predictors of microbial community composition, whereas soil organic carbon, phosphatase activity, and soil moisture were closely correlated with microbial carbon catabolism. This study indicated that soil microbial community composition and functional diversity are influenced by plants, nutrient availability, and enzymatic activity in the arid desert and serve as useful indicators for evaluating the soil quality and function of the desert ecosystem based on their relationships with the microbial community and soil nutrient distribution.