鄱阳湖典型洲滩湿地植被对低水位变化的响应研究

受气候变化和人类活动影响，鄱阳湖枯水期提前且持续时间延长，枯水位降低，洲滩湿地植被生物多样性受到威胁。生态水文模型能从河（湖）水-地下水-土壤水-植被角度系统分析低水位变化对洲滩湿地植被的影响，能克服传统研究的不足，但针对植被根系吸水深度的研究不足。本项目以鄱阳湖国家级自然保护区典型洲滩为研究对象，通过野外原位采样、实验室常规测试和稳定同位素技术相结合的实验方法，识别优势植被水分利用模式，揭示植被生长特征变量和土壤环境变量对植被水分利用模式的作用机理，确定不同时期植被根系吸水深度变化规律；在此基础上构建考虑根系吸水深度的典型洲滩湿地生态水文模型，研究不同低水位条件下典型洲滩湿地地下水和土壤湿度的时空分布特征，识别土壤水分胁迫及其对植被生长过程的影响，确定保障洲滩植被生态系统健康的湖泊低水位控制目标。研究成果对指导鄱阳湖水位调控具有重要的科学意义与技术支撑作用。

Affected by climate change and human activities, Poyang Lake suffers from some troubles, such as the earlier appearing, longer duration and lower water level in dry season than before, which affects vegetation biodiversity at islet wetland. Eco-hydrological models can systematically analyze the impact of low water level changes on vegetation at islet wetland from the perspective of river (lake) water-groundwater-soil water-vegetation continuum, and it can overcome the shortcomings of traditional research methods. However, the research on the depth of root water uptake in eco-hydrological models is insufficient. In this research, the typical islet in the Poyang Lake National Nature Reserve is taken as the research object. The experiment methods combining in-situ field sampling, laboratory routine testing and stable isotope technology, and statistical analysis methods such as correlation analysis and significance test are used. The water use strategies of dominant vegetation are investigated and on which the effect mechanism of vegetation growth characteristic variables and soil environmental variables is revealed. On this basis of the kind mentioned, the typical islet wetland eco-hydrological model considering root water uptake depth is developed to study the temporal and spatial distribution characteristics of groundwater level and soil moisture under different conditions of low water level in lake. Then the soil water stress and its impact on vegetation growth process at the typical islet wetland are identified. Finally, the allowable low-water-level in lake ensuring vegetation health at islet wetland is determined. The research has important scientific significance for providing technical support for the regulation of water level in Poyang Lake.