干旱半干旱区草地生态系统生产力主要受少且多变的降水和放牧影响，全球变化背景下降水时空格局的改变及放牧策略的调整将对草地生态水过程产生重要影响。研究表明过度放牧和降水改变是草地退化的主要影响因素，但改变降水和不同放牧条件对草地水文、土壤和植被过程的影响及其交互作用机制仍不明确。本项目拟通过在我国温带典型草原锡林郭勒草原进行改变降水和不同放牧处理试验，通过收集水文土壤要素在不同处理条件下的变化数据，开展改变降雨对不同放牧条件下土壤水分、蒸发和入渗等水文过程的影响研究；并结合植被观测数据分析改变降雨对不同放牧条件草地物种、群落及生物量的影响规律；最终运用数据分析和模型相结合的方法揭示不同放牧条件与降雨对草地水文土壤植被过程的交互影响机制。本研究对丰富草地生态水文理论体系，揭示草地水文、土壤和植被动态响应关系有重要意义，可为人类和自然双重变化环境下草地生态水文过程研究和草原可持续管理提供科学依据。

Grassland ecosystem production in arid and semiarid is mainly limited by low and variable precipitation and grazing. Spatio-temporal changes of precipitation pattern and grazing regimes under the globe change background supposed to have significant influence on grassland eco-hydrological process. Although previous studies identified that the main factors causing the degradation are overgrazing and precipitation variation, they have not examined how and to what the extent the grassland hydrological, soil and plant process have been influenced and interactive effected by altered precipitation and grazing or enclosure. This proposed project supposed to initiate a new experiment in a typical temperate grassland in Xilingol steppe to manipulate precipitation and grazing. The objectives of the proposed project are (1) to study soil moisture, evapotranspiration and infiltration and so on hydrological process response to altered precipitation and grazing or enclosure by collecting hydrological and soil data from different treatments, and (2) to quantify species composition, community and biomass variations under altered precipitation and grazing or enclosure by integrate plant observation data, and (3) to integrate experimental results into data analysis and models to improve our understanding of grassland hydrological, soil and plant process and their interactive effects of altered precipitation and grazing or enclosure. This proposed project will rich and perfect the theoretical foundation of grassland eco-hydrology, and also have significant meaning for confirming grassland hydrological, soil and plant interactive response with each other. The expected results of this project will provide scientific support to grassland eco-hydrological research and grassland sustainable development under human and natural caused environmental change.