Plant cover of Ammopiptanthus mongolicus and soil factors shape soil microbial community and catabolic functional diversity in the arid desert in Northwest China

Abstract

Although the spatial patterns of soil microbial community composition are well studied, little is known about the main factors driving microbial distributions in desert ecosystems. Therefore, the objective of this study was to examine the comprehensive effect of spatial scale, plant cover and environmental properties on soil microorganisms under Ammopiptanthus mongolicus canopies at 5 desert locations in Northwest China. Sampling site significantly influenced the soil microbial community structure and metabolic functions under A. mongolicus canopies. Variation of soil microbial communities was mostly attributed to the simultaneous effects of plant cover and soil factors, while purely plant cover explained more variation in catabolic function than did the principle coordinates of neighbour matrices (PCNM) and soil factors. Soil microbial structure and catabolic metabolism were both significantly affected by phosphatase, glomalin and soil organic carbon. Bacterial and actinomycete phospholipid fatty acids (PLFAs) were positively correlated with ammonium nitrogen (N), and the utilization of carbohydrates, carboxylic acids and amino acids was positively correlated with Olsen phosphorus (P). Bacteria (1.43–4.79 nmol∙g−1) were most common in the microbial community, followed by actinomycetes (0.54–1.89 nmol∙g−1) and fungi (0.29–0.48 nmol∙g−1). Carbohydrates (12%–85%) and amino acids (5%–59%) were the main carbon sources for soil microbes. Soil microbial community abundance and catabolic utilization were significantly higher in the rhizosphere of A. mongolicus than in the bulk soils, and principal component analyses (PCAs) significantly separated the rhizospheric soil microbes from those of infertile bulk soils. The results of this study support the conclusion that soil microbial composition and catabolic functional diversity in desert soils are spatially predictable and determined more by specific soil properties and plant cover than by large-scale distance. This research provides a basis for evaluating the management of soil resources and microbial function in desert environments.