荒漠草原多时空尺度蒸散演变特征及驱动机制研究--以宁夏盐池县为例

研究荒漠草原蒸散时空格局演变及其驱动机制，不仅能为荒漠草原生态系统维持机理研究提供科学支撑，而且可为地方政府制定生态治理政策提供决策依据。项目以宁夏盐池荒漠草原为研究对象，利用涡度相关系统获取近5年短时间尺度（小时到月度）的蒸散与能量交换特征，利用气象观测数据和彭曼模型估算近50年长时间尺度（年际和年代际）的潜在蒸散能力变化特征，利用MOD16蒸散数据和多种时空分析手段与检验方法获取近20年的蒸散空间分布特征和格局演变规律，从多种时空尺度来探讨荒漠草原蒸散的时空演变特征。在此基础上，运用经验模态分解、主成分分析和多元回归建模等技术，定量分析蒸散与气候变化、人类活动等诸多因子之间的关系，理清盐池荒漠草原蒸散能力变化和空间格局形成的驱动因素，探讨荒漠草原蒸散演变的驱动机制。研究成果将为地方政府应对气候变化策略、评估生态治理效益和制定农牧业发展政策提供科学依据和数据支持。

The study of spatiotemporal variation patterns of evapotranspiration and its driving mechanism in typical desert steppe has great significance since it not only can provides scientific support for the research of desert steppe ecosystem maintenance mechanism but also can guides local governments to make ecological management decision. In this study, the typical desert steppe in Yanchi County, Ningxia Province is selected as a case and its spatial distribution characteristics and temporal evolution of evapotranspiration will be studied from different spatial scales and multiple time scales. Firstly, using the eddy correlation system, about 5 years of evapotranspiration and energy exchange characteristics on short time scale (hours to monthly) will be observed in the study period. Secondly, the characteristics of potential evapotranspiration on long time scale (interannual and interdecadal) in the past 50 years will be estimated by the meteorological observation data and the Penman-Monteith model. Finally, base on the MOD16 evapotranspiration data and various spatio-temporal analysis method, the spatial distribution characteristics and temporal evolution of evapotranspiration in desert steppe in the past 20 years will be obtained. Base on the study of spatiotemporal variation patterns of evapotranspiration, a quantitative analysis of the relationship between evapotranspiration and those driving factors from climate change or human activities will be made through the empirical mode decomposition, principal component analysis and multiple regression model. The main factors that drive evapotranspiration changes in desert steppe will be found and the mechanism that drives evapotranspiration to evolute at different stages will be explored at last. This study will provide scientific basis and supporting data to local governments when making the response strategy to climate change, evaluating the benefits of ecological restoration projects and making the agricultural and animal husbandry development policy.