Vegetation and soil characteristics and their driving factors during restoration succession of degraded patches in alpine meadows of the Qilian Mountains, China.

We analyzed the characteristics and driving mechanisms of vegetation, soil, and microbial biomass along a restoration succession sequence of bare patches, short-term restored plant patches, and healthy alpine meadows in the Qilian Mountains, aiming to inform ecological restoration strategies for degraded alpine ecosystem. The results showed that bare patches supported only three plant species, with Ajania tenuifolia as the dominant one. Short-term restored patches contained 26 species, with Sibbaldianthe bifurca and Lancea tibetica as the dominant species. Healthy alpine meadows exhibited the highest species richness (40 species), dominated by Carex parvula and Elymus nutans. As restoration succession progressed, community height (1.3-4.1 cm), total biomass (239.2-3112.9 g·m-2), Patrick richness index (2.2-23.6), and Shannon diversity index (0.7-2.3) all increased significantly. Concurrently, soil pH and bulk density decreased, and soil water content increased. The contents of soil organic matter and total/available nitrogen, phosphorus, and potassium showed a unimodal response to succession, peaking in the short-term restored stage. Across all successional stages, soil nutrients exhibited strong surface accumulation, with higher concentrations in the 0-10 cm layer than in the 10-20 cm layer. Random forest analysis revealed that the explanatory rates of soil physical properties, total nutrients, available nutrients, and microbial biomass (MBC, MBN, MBP) for the variations of total plant biomass were 31.3%, 20.1%, 13.9%, and 34.7%, respectively. Similarly, their explanatory rates for species diversity were 44.0%, 6.1%, 6.9%, and 43.1%, respectively. Results of structural equation modeling confirmed that succession stage had strong positive and direct effects on both plant biomass (path coefficient=0.97) and species diversity (path coefficient=0.89). Overall, the findings demonstrated that vegetation community structure, productivity, and soil physicochemical properties improved synergistically during the restoration of degraded alpine meadow. Soil factors were the primary drivers of vegetation recovery, highlighting a significant positive coupling between vegetation restoration and soil improvement.