Altitude-driven variations in soil microbial communities of Himalayan subalpine forests

The Himalayas offer a unique environment for the study of microbial diversity and their response to biotic and abiotic factors, enhancing knowledge on ecological processes under altitudinal control in subalpine forests. This study investigates the impact of altitude on bacterial diversity and soil physico-chemical properties of Himalayan subalpine coniferous forests at four different regions-Sillery Gaon (S1; 1829 m), Gangotri (S2; 3415 m), Kausani (S3; 1890 m) and Gwal Dam (S4; 1940 m). Using 16S rDNA amplicon sequencing, soil microbial diversity of the said subalpine ecosystems were explored. Physico-chemical studies of the soil samples showed that S1 had the highest moisture content (25.66 ± 0.26%) and C:N ratio (136.26 ± 5.4) while S4 had the highest TOC (22.78 ± 1.2%), TKN (0.7373 ± 0.043%) and available phosphate content. Results indicated presence of diverse microflora from various phyla, including Actinomycetota (7.52% in S2, 7.98% in S3), Planctomycetota (53.36% in S1, 51.09% in S3), Proteobacteria (14.3% in S1, 18.28% in S3, 14.96% in S4), and Verrucomicrobiota (18.75% in S2 and 21.88% in S4). Proteobacteria was the dominant phyla in mid (S4) and lower (S1, S3) subalpine forest soils, suggesting enhanced abundance due to human intervention at these altitudes. Multivariate analysis revealed a positive correlation between altitude, precipitation, moisture content, soil pH, organic carbon, nitrogen and phosphate contents with the presence of Proteobacteria and Actinomycetota phyla. The study highlights the connection between microbial communities and soil physicochemical properties, and the intricate interplay of biotic and abiotic factors affecting the microbial community composition in a unique region at different elevations.

The online version contains supplementary material available at 10.1007/s13205-025-04608-8.