对比“生态退杨”政策实施前后洞庭湖湿地景观格局变化，综合分析洞庭湖区景观格局总体变化特征，为洞庭湖的景观格局优化提供科学依据。

以2014年、2016年和2018年Landsat-8卫星OLI遥感影像为数据源，利用多尺度分割分类技术方法对3期影像进行解译，结合多源辅助信息数据对解译结果进行修正，构建景观类型面积转移矩阵，并选取多个景观格局指数分析洞庭湖区实施政策前后各湿地景观类型面积变化及洞庭湖区景观格局变化总体特征。

①实施“生态退杨”政策后，洞庭湖区杨树覆盖面积共减少213.761 6 km²。②各湿地景观类型变化趋势各不相同，在2014—2016年和2016—2018年2个阶段：水域景观格局前阶段趋于破碎化，后阶段趋于整体化；防护林滩地面积在前阶段少量减少，在后阶段面积大幅减少，景观格局破碎化程度增强；苔草滩地面积在前阶段增加24.118 1 km²，后阶段减少114.904 3 km²，苔草滩地斑块数量增加、平均斑块面积减小，整体景观格局趋于破碎化；林地面积在两阶段内持续减少，但景观结构较为稳定，破碎化程度降低；农用地面积在2个阶段持续增加，景观格局趋于破碎化；建设用地趋于破碎化，但集约程度较高，聚集成众多较大斑块。③洞庭湖区湿地景观格局变化的总体特征如下：景观斑块聚集程度先减小后增大，景观破碎化程度先增强后降低；湿地景观多样性先上升后下降，景观优势度先下降后上升；景观异质性呈现先下降后上升的趋势；景观格局中斑块的形状：不规则性先增大后减小、复杂程度先增强后减弱。

在洞庭湖湿地实施“生态退杨”政策后，极大地优化了洞庭湖湿地景观格局，也促进了区域内生态环境的改善。

To compare the changes of the landscape pattern of Dongting Lake wetland before and after the implementation of the “Ecological Poplar Withdrawal” policy, and comprehensively analyze the overall change characteristics of the landscape pattern of the Dongting Lake area, and provide a scientific basis for the optimization of the landscape pattern of Dongting Lake.

Using 2014, 2016 and 2018 Landsat-8 satellite OLI remote sensing images as the data source, uses multi-scale segmentation and classification technology to interpret the third-phase images, and combines the multi-source auxiliary information data to modify the interpretation results to construct landscape type area transfer matrix, and multiple landscape pattern indexes were selected to analyze the area changes of wetland landscape types before and after the implementation of the policies in the Dongting Lake area and the overall characteristics of the landscape pattern changes in the Dongting Lake area.

After implementing the “Ecological Poplar Withdrawal” policy, the total area of ??poplar trees in the Dongting Lake area decreased by 213.761 6 km². The change trend of each wetland landscape type is different, in the two stages of 2014-2016 and 2016-2018: the water landscape pattern tends to be fragmented in the previous stage and integrated into the latter stage; the area of ??shelter forest land decreases slightly in the previous stage in the later stage, the area was greatly reduced, and the fragmentation of the landscape pattern was enhanced. The area of ??the moss beach increased by 24.118 1 km² in the previous stage and decreased by 114.904 3 km² in the later stage. The number of patches on the moss beach increased, the average patch area decreased, and the overall landscape pattern tended to fragment. The area of ??forest land continued to decrease in two stages, but the landscape structure was relatively stable and the degree of fragmentation decreased; the area of ??agricultural land continued to increase in two stages, the landscape pattern tended to fragment; the land for construction tended to fragment, but the degree of intensiveness is high, and many large plaques are gathered. The general characteristics of the change in the landscape pattern of the wetland in the Dongting Lake area are as follows: the degree of landscape patch aggregation decreases initially and then increases, and the degree of landscape fragmentation increases initially and then decreases; the wetland landscape diversity increases initially and then decreases, and the landscape dominance decreases initially and then increases. Landscape heterogeneity shows a trend of first decline and then increase; the shape of patches in the landscape pattern: irregularity increases initially and then decreases, and complexity increases initially and then decreases.

After the implementation of the “Ecological Poplar Withdrawal” policy, the government has greatly optimized the landscape pattern of the Dongting Lake wetland and promoted the improvement of the ecological environment in the region.