Fig. 1: Distribution of sampling sites and comparisons of microbial diversity and composition among various soil layers.

a Geographic distribution of the sampling sites across the Tibetan alpine permafrost region. Source of the spatial distribution of permafrost across the Northern Hemisphere is provided by the National Snow & Ice Data Center¹⁰³, while that of the Tibetan Plateau is obtained from ref. ⁶¹. The map was drawn by ArcMap 10.6 (Environmental Systems Research Institute, Inc., Redlands, CA, USA). Differences in microbial alpha diversity consisting of (b) taxonomic diversity (Shannon-Wiener index) (n = 22) and (c) phylogenetic diversity (Faith index) (n = 22) among three soil layers. Differences in microbial beta diversity consisting of (d) taxonomic variation (determined by pair Bray-Curtis distance) (n = 231) and (e) beta mean nearest taxon distance (Beta MNTD) (n = 231) among three soil layers. f The number of shared and unique ASVs among three soil layers. g Microbial composition and their differences among soil layers, only the top 10 phyla are shown here (n = 22). Different lowercase letters in box plots denote significant differences for the variables with soil depth (determined by two-sided pairwise Wilcoxon test, P < 0.05). *P < 0.05, **P < 0.01, ***P < 0.001, and ns: non-significant. SUR, surface (0–10 cm); SUB, subsurface (30–50 cm); PL, permafrost layer—the uppermost 50 cm thick layer of permafrost soil. Central line and whiskers in each box represent the median and 1.5 times the interquartile range, respectively. Boxes indicate the interquartile range between 25th and 75th percentile. Single points are outliers. Source data are provided as a Source Data file.