Seasonal and soil compartmental responses of soil microbes of Gymnocarpos przewalskii in a hyperarid desert

Abstract

The microbial communities associated with desert plants are influenced by many abiotic (such as soil factors, seasonal variations, etc.) and biotic factors, resulting in different microbial taxa. This study investigated the soil factors, microbial communities and microbial catabolism of Gymnocarpos przewalskii roots at different soil compartments (near-rhizosphere, far-rhizosphere, and blank soil) in three seasons (summer, autumn, and winter) from two sites in the hyperarid desert, northwest China. Microbial biomass and activity were relatively high in summer in the near-rhizosphere, whereas the fungal-bacterial ratio was dominant in autumn. Gram-negative bacterial biomass was the highest irrespective of season, and catabolic activity was dominated by carbohydrate, amino acid, and polymer metabolism for all three seasons and soil compartments. The influence of seasons and soil compartments on soil microbial composition mainly depended on their interactions with soil factors. Temperature, soil saccharase, alkaline phosphatase, and NO₃⁻-N content were the main factors determining microbial composition and carbon source metabolism. Moreover, environmentally induced changes in soil humidity increased glomalin content by affecting the arbuscular mycorrhizal fungal (AMF) PLFA biomass, which affected carbon sequestration, ultimately influencing AMF colonization. Understanding the feedback processes among organisms in desert soils was important for exploring the survival and protection strategies of desert relict plants.