Soil Microbial Community Responds to Elevation Gradient in an Arid Montane Ecosystem in Northwest China

Abstract

This study sought to clarify the composition of soil fungal and bacterial communities along an elevation gradient in an arid montane ecosystem as well as the influence of environmental factors (soil properties, climate, topography, and plant diversity) upon soil microbial community structures. Four vegetation types—montane desert steppe (mean elevation: 1761 m), montane shrub (mean elevation: 2077 m), subalpine coniferous forest (mean elevation: 2485 m), and subalpine shrub (mean elevation: 2903 m)—were sampled on the western slope of the Helan Mountains. The 16SrRNA gene and ITS1 were performed by single-molecule real-time (SMRT) sequencing with the PacBio sequencing platform. The Chao1 and Shannon–Wiener diversity of soil fungi and bacteria were more diverse in the soil of the lower elevation gradient compared to that of the upper one. Differences in abundance among phyla were found via One-way ANOVA(analysis of variance), yet the dominant soil fungal phyla (Ascomycota, Basidiomycota, and Mortierellomycota) and bacterial phyla (Proteobacteria, Acidobacteria, and Bacteroidetes) were the same across the elevation gradient. Pearson correlations and redundancy analysis (RDA) indicated that plant diversity (Shannon–Wiener diversity [H] and Margalef richness [D]), solar radiation, mean annual temperature, soil organic matter, soil moisture content, slope, mean annual precipitation, and elevation all significantly influenced the community composition of different soil fungal and bacterial phyla. Although plant diversity significantly affects fungal and bacterial diversity, the results imply that the influence of plant functional diversity on soil microbial community variation should not be ignored.