Differential responses of soil microbial metabolic limitation and carbon use efficiency to long-term grazing exclusion across three grassland types in Xinjiang.

Introduction: Long-term grazing exclusion is widely used to restore degraded grasslands, yet whether its effects on soil microbial metabolism-particularly nutrient limitation and carbon use efficiency (CUE)-vary among grassland types remains poorly understood. Methods: We investigated three typical grassland types in Xinjiang, China: temperate desert (TD), temperate steppe (TS), and mountain meadow (MM), under 12 years of grazing exclusion and free grazing. We measured soil extracellular enzyme activities, assessed microbial nutrient limitation via vector analysis, and calculated microbial CUE. Results: Grazing exclusion produced contrasting effects among grassland types. In TD, all three enzyme activities significantly increased ( Discussion: Our findings demonstrate that grazing exclusion effects on microbial metabolism are strongly grassland-type dependent. Grazing exclusion promoted favorable microbial functional responses in TD and TS, but intensified C limitation and reduced CUE in MM. Vector length and angle serve as sensitive indicators of microbial nutrient limitation during restoration. These findings highlight the need for ecosystem-specific restoration strategies in arid and semi-arid regions.