通江湖泊典型洲滩湿地植被时空格局演变对水位波动的响应机制研究——以鄱阳湖为例

In view of the extensive degradation of lake wetland ecosystem induced by profoundly modified relationship between the Yangtze River and its connected lakes, this research focuses on the eco-hydrological processes in the lake wetland, investigating the spatiotemporal dynamics of typical beach wetland vegetation distribution patterns in Poyang Lake and the associated driving mechanism under the pressure of dramatic water-level fluctuations. The positioning monitoring, sampling and laboratory analysis, RS, GIS, Classification and Regression Tree (CART), and Bayesian Hierarchical Model (BHM) will be utilized in this study. The spatiotemporal changes of typical beach wetland vegetation distribution on the scales of landscape and vegetation community over the past 30 years will be revealed and the most significant water-level fluctuation indicators that impact these changes will be detected. Furthermore, the driving mechanism and the spatial heterogeneity of the relationships between changes in the distribution of wetland vegetation and the associated water-level fluctuation indicators will be measured quantitatively. Wetland distributed on different kind of landforms with different water level fluctuation patterns during dry seasons, the representative estuarine delta, opening dish-shaped billabong and controlled dish-shaped billabong, will also be selected as the sample zones to develop scientifically defensible and empirically testable relationships between changes in wetland vegetation distribution patterns and water level fluctuation factors combined with those underlying environmental factors, thereby we can finally separate the impact contributions of water level fluctuation factors on the patterns of typical beach wetland vegetation communities. This study will devise a methodology to study the eco-hydrological processes in wetland surrounding shallow lakes, especially for those lakes naturally connected to upstream and downstream rivers. And results of this study will help water resource managers to make informed decisions about how to protect the degrading wetland ecosystems.

以通江湖泊湿地生态-水文过程的耦合研究为核心，针对近年江湖关系变化对通江湖泊湿地生态系统产生影响等问题，以鄱阳湖水位波动驱动的湿地植被空间格局演变过程研究为主线，借助野外定位观测、采样与实验室分析、遥感与地理信息系统、分类与回归树（CART）、贝叶斯层次模型（BHM）等方法和手段，从景观和群落两个尺度，揭示近30年不同时段鄱阳湖典型洲滩湿地植被时空格局变化过程，定量识别影响鄱阳湖洲滩湿地植被空间格局变化的关键水位波动变量及其影响机制、空间差异，阐明河口三角洲、被控碟形洼地和未控碟形洼地三种洲滩不同的水位波动模式及气象、土壤等其他环境因子对湿地典型植物群落变化的协同作用机制和空间异质性，辨识水位波动对洲滩湿地植物群落空间格局的影响分量，提出维持湿地生态系统健康的水资源管理策略，为通江湖泊湿地生态-水文过程的耦合研究提供范式。

以通江湖泊湿地生态-水文过程的耦合研究为核心，以高水位变幅驱动鄱阳湖洲滩湿地为对象，借助遥感与GIS技术、野外监测、室内实验、多尺度时空间模型模拟等方法，系统分析了近30年鄱阳湖不同时间尺度水位波动变化规律，重建了洲滩湿地植被景观带、湿地植被群落地表生物量空间分布格局的演变过程，揭示了驱动湿地植被空间格局变化的关键因子。研究表明，近30年鄱阳湖典型植被景观带分布面积呈增加趋势，平均高程分布下限呈下移趋势；典型植被景观带分布面积和高程对季节尺度水位变量存在响应关系，丰水和退水期的水情影响植被的分布面积，退水情的水情影响植被分布高程；冲积三角洲洲滩湿地地表生物量明显高于碟形洼地洲滩湿地，闸控碟形洼地洲滩地表生物量略高于无闸控碟形洼地洲滩；鄱阳湖湿地典型植被地表生物量的分布受水位波动及土壤理化因子等的共同影响，对于三种洲滩水分条件均是影响其地表生物量的主导因子。本研究探讨了通江湖泊特殊的水文过程对湿地生态系统影响研究的新思路和新方法，对长江经济带生态系统健康和可持续发展具有实践指导意义。