Depth‐ and Elevation‐Dependent Contributions of Bacterial Generalists and Specialists to Soil Multifunctionality in a World Natural Heritage Mountain Ecosystem

ABSTRACT Little is known about the vertical differentiation of generalist and specialist microbial groups within soil profiles and their impact on ecosystem multifunctionality (EMF) along altitudinal gradients. In this study, soil samples were collected from multiple depths at permanent plots in the UNESCO World Natural Heritage site of Fanjing Mountain at varying altitudes. High‐throughput sequencing, combined with linear mixed‐effects models and interpretable machine learning analyses, was employed to investigate microbial community structure, diversity, network characteristics, assembly processes, and the driving factors of EMF. Soil water content increased significantly with altitude ( p < 0.05), while catalase activity decreased with altitude; both parameters were higher in surface soils compared to deeper layers. Generalists were more abundant in surface soils, whereas specialists exhibited a higher turnover rate and frequently transitioned to generalists. The Shannon diversity indices of the two groups differed between soil layers, with the Shannon diversity of specialists in deep soil showing a significant positive effect on EMF ( p < 0.05). Network complexity and stability varied with soil depth. EMF in topsoil was primarily influenced by soil physicochemical properties, whereas EMF in subsoil was more strongly affected by climatic variables. These findings highlight the critical roles of altitude, soil depth, and environmental heterogeneity in shaping the differentiation of microbial communities and ecosystem functions in mountainous regions.