鄱阳湖水文情势过程对典型湿地景观动态变化的影响

Influence of Water Regime on Landscape at Typical Delta Wetland in Poyang Lake

以鄱阳湖赣江主支口三角洲湿地1973年~2009年16景遥感影像为基础,利用决策树分类分析近40年来赣江主支口三角洲不同湿地景观类型的组成结构及其演变趋势;并结合遥感影像对应的当天水位,探明水情变化与赣江主支口三角洲湿地景观类型面积之间的动态响应关系。结果表明,近40年来鄱阳湖水位变化以及4种特征水位的淹没天数都是呈现下降的趋势;植被面积呈增长趋势,而水体和裸露洲滩的面积均呈现减少趋势,且裸露洲滩的面积下降速率大于水体面积;水位变化与水体面积拟合关系最优,植被次之,与裸露洲滩拟合最差。研究结果能够进一步阐明鄱阳湖水情变化对典型湿地景观类型空间格局的影响,有助于维持鄱阳湖湿地生态系统结构与功能的稳定。

The evolution laws and composition structure of landscape at Ganjiang main-branch delta wetland in Poyang Lake are studied by the decision tree classification of the autumn remote sensing images during the period of 1973--2009. As well as, the dynamic relationship between water regime and areas of three kinds of landscape are explored by combining with the corresponding water levels of Landsat images at typical delta wetland in Poyang Lake. The results showed that： （a） the water level of Poyang Lake and flooded days of four characteristic water levels both present consistent decrease trends in past 40 years; （b） the area of vegetation is increased, while the areas of water and bare delta wetland are decreased and the bare delta wetland is with a faster declining rate; and （c） the linear fitting relationships between water level and water area is best, then with vegetation, and the bare delta wetland is worst. The results could further explain the effects of water regime on spatial patterns of wetland landscapes, which is helpful to maintain the stability of Poyang Lake wetland ecosystem＇s structure and function.