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

内容摘要

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. 本文以祁连山区裸露斑块、短期恢复植物斑块及健康高寒草甸作为恢复演替序列,分析了植被、土壤和微生物生物量特征及其驱动机制。结果表明:裸露斑块仅分布3种植物,优势种为细叶亚菊;短期恢复植物斑块有26种植物,优势种为鸡冠茶和肉果草;健康高寒草甸有40种植物,优势种为高山嵩草、垂穗披碱草。随恢复演替推进,群落植株高度(1.3～4.1 cm)及生物量(239.2～3112.9 g·m-2)、Patrick指数(2.2～23.6)、Shannon指数(0.7～2.3)均显著上升,土壤pH与容重降低,含水量提高,而土壤有机质及氮、磷、钾全量和速效养分呈先增后减趋势。各演替阶段土壤养分均表现出表聚特征,0~10 cm土层均显著高于10～20 cm。随机森林分析表明,土壤物理性质、全量养分、速效养分及微生物生物量(MBC、MBN和MBP)对植物总生物量变异的解释率分别为31.3%、20.1%、13.9%、34.7%,对物种多样性的解释率分别为44.0%、6.1%、6.9%、43.1%。结构方程模型表明,演替阶段与植物总生物量(路径系数为0.97)、物种多样性(路径系数为0.89)具有较强正向作用。综上,祁连山退化斑块恢复演替过程中,植被群落、生产力与土壤结构协同改善;土壤因子是调控植被性状的核心要素,植被恢复与土壤环境改良呈现显著正向耦合效应。.