三峡建坝前后洞庭湖区湿地景观格局变化

根据洞庭湖区1987—2008 年的6 期遥感影像数据资料，利用景观格局指数及转移矩阵模型等方法重点分析了三峡工程建坝前后洞庭湖区湿地景观格局的变化特征，以及对洞庭湖区湿地演变的主要影响。结果表明：①整体景观破碎化程度增大，景观异质性减小，景观形状趋于复杂化；②水体的破碎化程度增加，斑块间的结合度降低；泥沙滩地的破碎化程度先加大后降低，最大斑块面积有所增大；苔草滩地和芦苇滩地的破碎化程度先后经历了增大→减小→增大的过程；防护林滩地的破碎化程度由减小到增大到再增大；耕地（水田、旱地）破碎化程度在逐渐增大；建设用地斑块数增加最多；林地的结构相对稳定；③三峡工程运行使洞庭湖区湿地的水沙和泥沙淤积发生变化，导致湿地呈正向演替，自然湿地面积减少。

Changes in Dongting Lake Wetland Landscape Pattern Related to Pre- and Post-Construction of the Three Gorges Dam

Taking six periods of TM images of Dongting Lake area in 1987, 1993, 1998, 2003, 2004 and 2008 as data source, with the aid of geographic information system software and the landscape pattern software, extraction data on Dongting Lake wetland landscape pattern, using landscape pattern indices and the transfer matrix model methods, this paper focuses on the analysis of the pre- and post-construction of the Three Gorges project and its operation, dynamic change characteristics of landscape pattern in the Dongting Lake wetland, and the main influence on the evolution of the Dongting Lake wetland. The results show that: 1) The whole landscape fragmentation degree increases, the landscape heterogeneity decreases, and landscape shape tends to be complicated. 2) The fragmentation degree of water body increased, and the combination degree between patches reduced; the sediment beach fragmentation degree increased first and then reduced, the biggest patch area increased; the broken degree of moss grass and reeds has gone through an increase, decrease and increase process; the broken degree of protection forest beach experienced a reduction to increase to increase again process; the broken degree of cultivated land (paddy field and dry land) is increasing gradually, the patches of construction land increased the most; the structure of forest land is relatively stable. 3) Change in water and sediment and sediment deposition of the Dongting Lake wetland has taken place under the operation of the Three Gorges project, leading to a positive succession of wetland and a reduction of natural wetland area.