漓江流域岩溶区森林土壤关键磷循环过程及其对氮沉降的响应机制研究

岩溶区森林生态系统敏感且脆弱，极易受全球环境变化的影响。大气氮沉降增加必然会引起土壤氮库大小发生改变，可能影响土壤磷循环过程，而磷循环对岩溶区退化森林生态系统植被恢复具有重要作用。因此，探究岩溶区森林土壤磷来源、循环过程以及对大气氮沉降的响应规律和内在机制对岩溶区退化生态系统恢复和可持续发展十分必要。本项目拟以漓江流域岩溶区植被不同恢复阶段森林为研究对象，通过野外长期连续监测雨水、凋落物和植物根系磷输入及土壤磷库动态变化，阐明岩溶区森林土壤磷主要来源及其影响因素；采用野外原位培养试验，分析森林土壤磷分级特征、磷库组分季节和年际变化规律，明确岩溶区森林土壤关键磷循环过程及其控制因素；通过模拟氮沉降野外和室内培养试验，揭示氮沉降对岩溶区森林土壤磷转化过程的影响以及微生物调控机制。研究结果将为深入认识和探究在全球环境变化情景下岩溶区退化森林生态系统植被恢复和可持续发展提供科学参考。

Forest ecosystems in karst areas are fragile and sensitive to global environmental change. The increase of atmospheric nitrogen deposition will inevitably cause the changes of soil nitrogen pool and may affect the soil phosphorus cycle, which plays an important role in vegetation restoration of degraded forest ecosystems in karst areas. Therefore, it is of great significance to explore the phosphorus source and cycle in forest soils, and to examine their response to atmospheric nitrogen deposition in karst areas. This research will be conducted in the forests at different vegetation restoration stages in the karst area of the Lijiang river basin, China. The first objective is to clarify the main source of phosphorus and its influencing factors in forest soils by continuously monitoring the dynamics of phosphorus inputs from rainfall, litters and plant roots and the changes of soil phosphorus pool in the field for a long time. The second objective is to identify the key phosphorus cycling process and its controlling factors in forest soils by analyzing the phosphorus fractionation characteristics and the seasonal and inter-annual variations of phosphorus pools in forest soils in a situ experiment. The third objective is to reveal the effects of nitrogen deposition on phosphorus cycling process of forest soils and the underlying mechanism of microbial regulation in field and incubation experiments simulating atmospheric nitrogen deposition. The results can provide a scientific reference for further understanding and exploring the vegetation restoration and sustainable development of degraded forest ecosystems in karst areas under the global environment change scenario.