Increasing Elevation Reduces Complexity of Soil Microbial Co-occurring Network in Changbai Mountains, China

Elevation patterns and assembly processes of soil microbial community structures are essential for understanding biogeochemical processes in mountain systems. Differences in soil properties caused by elevation gradients can regulate the spatial distribution and network complexity of the community structure. To explore the variations in soil microbial community structures and their assembly mechanisms across different elevations of the Changbai Mountains, as well as their responses to environmental factors, we collected microbial samples along an elevational gradient (seven elevations containing four vegetation zones) on the western slope of the Changbai Mountains using the method of metagenomic sequencing. The results showed a significant difference (P < 0.05) for the Chao1 index across different elevations, but no significant difference was observed for the Shannon and Simpson indices. With increasing elevation, the number of nodes and links in the microbial network gradually decreased. Acidobacteria were highly connected to many nodes. The microbial communities indicated a significant distance-decay relationship (P < 0.001) and were affected more by stochastic processes along the elevation gradient. The results of the Structural Equation Model (SEM) showed that elevation had direct significant effect on carbon (C, P < 0.01), nitrogen (N, P < 0.01), and phosphorus (P, P < 0.05) and weak negative effect on their ecological stoichiometry. Elevation was one of the major variables contributing to microbial network topology. The contribution of C and N to microbial network complexity was higher than that of P. Our study provides valuable insights into the responses of soil microbial communities to elevation variations.