How forest ecosystems regulate soil microbial diversity and function in the northeastern Tibetan Plateau?

Climate shifts exert a pronounced influence on the northeastern Tibetan Plateau, where forest ecosystems play a pivotal role in sustaining ecological equilibrium at both local and global scales. However, knowledge of how soil microbial communities are structured and how they function across the varied forest types in this region remains notably incomplete. This study investigated five contrasting forest types across the northeastern Tibetan Plateau to characterize the community structure, functional divergence, and environmental predictors associated with keystone bacterial and fungal lineages in the soil. The key findings are summarized below. (1) Soil physical properties were significantly and negatively associated with bacterial species diversity indices, whereas they showed no discernible relationship with fungal diversity. (2) Soil nutrient availability was markedly and positively related to both bacterial species and functional diversity indices, yet exhibited minimal association with those of soil fungi. (3) Conversely, soil enzyme activities were negatively associated with bacterial species and functional diversity indices, but were significantly and positively related to the functional diversity index of soil fungi. (4) Specific predictor analysis revealed that soil water content (SWC), ammonium nitrogen (NH4+-N), available phosphorus (AP), and soil urease (S-UE) interactively correlated with bacterial species and functional diversity indices, whereas S-UE emerged as the primary predictor associated with the fungal functional diversity. This study provides localized insights into potential pathways through which environmental factors relate to the distinct diversity patterns and functional capacities of soil microbiota in high-altitude forest ecosystems.