干热河谷稀树灌草丛生态系统对降水增加响应的控制实验研究

在光热资源丰沛的干热河谷区域，以受水分限制的稀树灌草丛生态系统为研究对象，紧扣该区域的主控因子――降水，关注生态系统对降水格局变化响应及机制这一科学问题，本着有限经费，有限目标原则，在已有长期降水减少人工控制实验的基础上，实施生态系统尺度不同强度降水增加人工控制实验，进一步完善受水分限制的干热河谷稀树灌草丛生态系统对降水格局变化响应的控制实验平台；实施生物调查、树干液流观测和土壤温室气体监测等，开展多学科综合研究，探讨干热河谷稀树灌草丛生态系统植物群落、树木蒸腾、水分利用效率（WUE）对降水增加的响应；把握降水增加对干热河谷稀树灌草丛生态系统土壤温室气体排放的影响；揭示干热河谷稀树灌草丛生态系统对不同强度降水增加的响应及机制。研究成果可为阐明干热河谷稀树灌草丛生态系统对降水格局变化的响应及机制奠定基础，对把握未来气候变化情境下干旱、半干旱地区的生态系统响应及机制具有重要意义。

Water is often the important limiting factor in a Savanna ecosystem, where the solar-thermal resources are abundant. In this project, we will focus on water as limiting factor with response to changing pattern of precipitation in the savanna ecosystem, Yunnan. Based on the principle of limited funds and limited objectives, the proposed research work will improve the exiting drought experiment platform. We will also establish a precipitation increased platform with different precipitation intensities at the ecosystem scale to better understand the response of water as limited factor. The proposal will study the response of plant community, tree transpiration and ecosystem water use efficiency (WUE) with references to increases of precipitation through stem sap flow observation and soil greenhouse gas (GHGs) flux monitoring. We will also identify the influence factors of precipitation patterns on soil GHGs emission in savanna ecosystem. The expected research outcomes are to lay a foundation for in-depth study on the response mechanism of the savanna ecosystem with changing pattern of precipitation as long-term study. Further, study will also deliver the better understanding of response mechanism of the ecosystem in the arid and semi-arid locations to the future climate change situation.