基于Landsat的黄河三角洲湿地景观时空格局演变

为全面揭示黄河三角洲湿地景观的演变，利用1973~2016年9期Landsat卫星影像，构建黄河三角洲湿地景观空间数据库，分析区域湿地景观的组成及其变化，应用景观格局指数分析方法，研究湿地景观格局演变的趋势，并结合质心模型探讨湿地景观空间位置的变化.结果表明：（1）黄河三角洲咸水湿地多分布于海岸带附近，淡水湿地多分布于河流沿岸，人工湿地多分布于距离海岸线15km以内的沿海区域以及河流沿岸.（2）黄河三角洲湿地总面积呈下降趋势，是由芦苇沼泽、翅碱蓬柽柳沼泽以及芦苇柽柳沼泽为主的自然湿地向人工湿地和非湿地的转换变化导致.（3）黄河三角洲湿地景观整体呈破碎化的萎缩趋势，景观空间构型不断朝破碎化、多样化，形状简单化的人工化特征突出的方向发展.（4）1973~1985年间，受黄河由刁口河流路改道清水沟流路初期的影响，加上充沛的淡水水源，黄河三角洲湿地呈以淡水湿地的东北向扩张变化主导；1985年后，黄河处于改道清水沟流路中后期，后又改至清8汊流路，加上黄河径流量的减少，使得区域湿地景观整体呈咸水湿地主导的东南方向萎缩变化.

Spatial and temporal variations in wetland landscape patterns in the Yellow River Delta based on Landsat images

A spatial database of wetland landscape was constructed by using Landsat images from 1973 to 2016 to reveal the evolution of the wetland landscape in the Yellow River Delta. In this study, the composition,spatial and temporal variations in wetland landscapes were analyzed. Besides, the evolution trend of wetland landscape pattern was also discussed based on landscape pattern index. Moreover, combining with the centroid model, the spatial location variations in wetland landscapes were analyzed. The results showed that salt marshes in the Yellow River Delta are mostly located around the coastal belts, and the freshwater wetlands are mainly distributed on both banks of the Yellow River, while the artificial wetlands are mostly distributed around the coastal areas within 15km away from the coastline and the Yellow River banks. Over the whole study period, the total area of wetlands in the Yellow River Delta showed a descending tendency. Because large area of natural wetlands which were dominantly covered by reed, suaeda heteroptera-Ttamarisk and reed-Ttamarisk, were converted into artificial wetlands and non-wetlands. The wetland landscapes of the Yellow River Delta showed a trend of area shrinking and fragmentation. The spatial configuration of wetland landscapes was fragmented, diversified, and shape was simplified, which was characterized of artificial wetland landscapes. As affected by the Yellow River changing from Diaokou to Qingshuigou, and its sufficient water supply, wetlands in the Yellow River Delta mainly expanded to the northeast direction which was dominated by freshwater wetlands during the period from 1973~1985. After 1985, the Yellow River changed from Qingshuigou to Qingbacha, besides, the runoff of the Yellow River was cut down. The wetland degradation occurred in the southeast of the Yellow River Delta. That spatial location variations in the Yellow River Delta was mostly controlled by the salt marshes in the whole period.