Pattern and drivers of soil fungal community along elevation gradient in the Abies georgei forests of Segila mountains, Southeast Tibet

Soil fungi are a diverse group of organisms extremely crucial to forest nutrient cycling and carbon (C) storage. The elevational pattern of soil microbial diversity has been widely studied, but how soil properties, elevation, and their association affect fungal community in subalpine forests remain to be explored. Here, soil fungal community diversity was investigated using high -throughput sequencing along an elevation gradient (3500-4300 m a.s.l.) in the Abies georgei var. smithii forests, a typical subalpine forest type in the Segila Mountains of Southeast Tibet. Elevation significantly affected the soil properties. Available phosphorus (P), total nitrogen (N), and soil organic C (SOC) increased whereas pH decreased with elevation. A U-shaped pattern for fungal diversity was found in topsoil while a slight monotonically decreasing pattern in subsoil layer across the elevation gradient. Basidiomycota, Ascomycota, and Mortierellomycota were the top three dominant phyla, and ectomycorrhizal fungi were the dominant functional fungi group in the A. georgei forest soils. Significant negative correlations were observed between fungal OTUs richness and NO3 -(r =-0.431, p < 0.01), indicating that soil N availability is an important factor for fungal diversity. Based on redundancy analysis, soil factors explained 32.1% of the total variations in composition structure of fungal community. Soil pH, moisture, and fertilities (i.e., SOC, TN, TP, NO3-) were independent factors affecting the fungal community composition. Collectively, the alterations in soil environmental factor across elevations are essential in shaping the soil fungal diversity and community composition in the A. georgei forests in Segila Mountains, Southeast Tibet.