Alpine Secondary Forest Types Influence Soil Microbial Community Structure and Enzyme Activities on the Eastern Qinghai–Tibet Plateau

Soil microbial communities and enzyme activities influence soil functions and tree growth in ecologically fragile alpine regions. However, differences in soil microbial communities among secondary forests remain poorly understood in the Qinghai–Tibet Plateau. Here, we aimed to investigate soil microbial communities and their environmental interactions across different forest types. Litter and soil samples were collected from four coniferous stands, including Picea crassifolia (PC), Picea wilsonii (PW), Picea tabuliformis (PT), and Salvia przewalskii (SP), and two broad‐leaf stands, including Betula platyphylla (BP) and Prunus davidiana (PD), in the eastern region of Qinghai Province. High‐throughput sequencing was employed to analyze soil microbial communities. Soil enzyme activities, litter characteristics, soil properties, and their correlations with the microbial community were examined. The results indicated that primary bacterial genera included RB41 , Candidatus Udaeobacter, Sphingomonas , Mycobacterium , and Ellin6067 across six forest types, with RB41 exhibiting significantly lower abundance in PC. The dominant fungal genera were Mortierella , Inocybe , Leptodontidium , and Penicillium . Fungal Chao1, Shannon, and Pielou indices were significantly higher in broad‐leaf forests than in coniferous forests and exhibited greater sensitivity to environmental factors than bacterial diversity. β‐glucosidase and N ‐acetyl‐glucosaminidase activities were significantly higher in PC than in other forests. Partial least squares path modeling demonstrated that forest type indirectly influenced soil microbial communities through soil physicochemical properties. Overall, forest type significantly affects microbial community composition, with broad‐leaf forests exhibiting higher fungal diversity than coniferous forests. These findings provide a theoretical basis for the establishment of mixed coniferous‐broad‐leaf forests in the ecological restoration of alpine regions.