构件属性演变对高寒草地水源涵养功能的影响及发生机制

Alpine grasslands have exerted huge effects on the function of Chinese water tower on the Tibetan Plateau. However, alpine grasslands are continued suffering from global climate change and long-term anthropogenic activity such as overgrazing. Thus, the characteristic of seriously degradation were manifested on the Tibetan Plateau, with multi-pathway and multistability, and heavy damage. The area of degraded grassland covers more than 1/3 of the total grassland areas. Because of a major change in alpine meadow component properties of water conservation, effects were interesting on alpine grassland water conservation function and mechanism. This scientific question were yet paid much attention, thus, there were much uncertainty in the function of water conservation by alpine meadow. Furthermore, the relationship is also unclear between water conservation function and grassland of remaining multistability stage, compared with native and seriously degraded grassland. In addition, to accurately estimate the potential water conservation stock, the temporal and spatial differentiation should be taken into account. Nowadays, three kinds of representative vegetation (alpine Kobresia meadow, alpine shrub, and alpine wetland) were studied by field observation and manipulated monitoring, and multi metadata fusion. The coupling relationships were focused on in this study among anthropogenic disturbances and component attribute and eco-hydrological process and hydrological regulation, and water conservation function. The above contents under metastable grasslands were carried out at different scales from plots, local plots, and small watershed to large region ( the Yangtze River source area, the Yellow River source areaand the Qilian mountain region). Then, we can confirm the coupling linkage mechanism between alpine grassland ecological hydrological processes in relation to the evolution of the grass and. Meanwhile, adjusting function evaluation was attempted based on multi-source data fusion for large scale grassland hydrological. To sum up, this study would further deepen the mechanism, between grassland water conservation function and natural and anthropogenic disturbances. This research could provide theory support for prediction of water conservation, and adaptive management in alpine meadow.

高寒草地是青藏高原“中华水塔”功能发挥的主体，呈现出“多途径、多稳态、重危害”的退化演替特征。草地退化可导致系统水源涵养构件属性和生态水文过程发生重大改变，影响了高寒草地水源涵养功能，这一科学问题没有得到足够重视，造成高寒草地在高原水源涵养功能贡献评估的不确定性。本项目以广泛分布于青藏高原的代表性植被，高寒嵩草草甸、高寒灌丛和高寒湿地为研究对象，采用野外观测、实验模拟和多源数据融合的研究手段；对处于多稳态的退化草地，从斑块(样方)、局地(样地)、小流域（样带）和区域(长江源区、黄河源区和祁连山区)不同尺度上，以干扰-构件属性-生态水文过程-水源涵养功能演变为主线，明晰高寒草地生态水文过程与草地演化的耦合关系及协同机制，基于多源数据融合进行大尺度草地水源涵养功能评估，深化高寒草地生态水文学理论，为保障我国水资源的生态安全提供理论依据。

该项目以广布于青藏高原的高寒矮嵩草草甸和高寒金露梅灌丛草甸为研究对象，将高寒草甸划分为7种退化稳态，高寒寒金露梅灌丛草甸划分为4种退化稳态，采用现场调查、结合无人机技术、室内分析，进行了不同植被类型、不同退化稳态下的草地植被构件、下垫面破碎化特征和影响水分涵养的土壤构件属性特征研究；将高寒草地水分划分为降水、土壤水、植物水、浅层地下水、中层地下水、河水、沼泽水和露水8种贮存态，基于稳定性同位素技术、Lysimeter及测流堰，进行了水分迁移通径及季节动态的研究；基于不同植被、不同演替稳态土壤储水量、土壤构件属性构建了青海高原高寒草地的水源涵养功能估测的经验模式；通过青海高寒草地不同退化状态的调查，建立了遥感NDVI指数-植物构件属性-下垫面特征-土壤构件属性-土壤水源涵养功能评估的对应关系，定量估算了草地退化对水源涵养量的影响。本项目的开展丰富了高寒草地生态学内涵，为进行基于不同稳态高寒草地区域水源涵养功能的评估，提供技术方法，亦可为重大生态工程实施对高寒草地水源涵养功能提升作用的评估，提供借鉴