通过大规模石漠化治理工程的实施，喀斯特地区植被恢复效果明显，但土壤肥力恢复呈现滞后性，且不同植被恢复阶段土壤养分限制性各异。植物细根分泌物对土壤养分限制缓解具有重要作用，但其作用机制在喀斯特地区尚不明确。申请项目拟以喀斯特峰丛洼地不同植被恢复阶段为研究对象，采用原位收集法研究优势植物细根分泌物的主要组分、含量和分泌速率，明确植被恢复过程中细根分泌物响应土壤养分限制的动态变化；通过定位监测及13C自然丰度法探讨植物细根分泌物与土壤有机质降解、氮矿化和磷形态转化的关系；结合植物细根养分积累和共生菌根真菌侵染率等分析，揭示植被恢复过程中植物细根分泌物缓解土壤氮磷养分限制的作用机制。研究结果能为喀斯特脆弱生态系统植被优化配置和可持续恢复提供科学依据。

Attributed to the ecological restoration projects and rocky desertification control projects, the net primary productivity, biomass, and vegetation coverage of karst ecosystem has been improving in Southwest China. However, the deficiency and component difference of soils are the primary limited factors for vegetation restoration, resulting in N limitation in earlier stage but P limitation in later stage of vegetation succession. The increasing of fine root exudations is the important adaptive mechanism for plants to adapt soil nutrient deficiency, but it has been neglected in the previous research about the evolution mechanism between vegetation restoration and soil nutrients in the karst region. In this research, we will analyze the differences of component, quantity, and exudate rates of fine root exudations in different vegetation successional stages to find the regularity of fine root exudations response to the changes of soil nutrients. We will explain the effect of the component, quantity, and exudate rates of fine root exudations on soil organic matter degradation, nitrogen mineralization, and transformation of phosphorus forms by the field experiments and natural 13C abundance. Combining the above parts of study and soil nutrients uptakes and symbiotic infection rates of mycorrhizal fungi in fine roots, we will reveal the mechanism of plant fine root exudations relieving N and P limitations along vegetation successional stages, which can provide a scientific basis for sustainable recovery of vegetation in the karst fragile ecosystem.