洪泽湖河湖交汇区土地利用时空动态

河湖交汇区是洪泽湖湿地最重要的生物资源库与缓冲带,区域土地利用变化是研究湿地演化及驱动因素的重要手段。以淮河与洪泽湖在老子山镇(118.454°～118.692°E,33.166°～33.188°N)形成的河湖交汇区湿地为对象,对区域2003年、2008年、2013年三时相的高分遥感影像进行数据处理与信息提取,利用GIS技术和重心模型对10年间土地覆盖类型的时空转化特征、变化趋势及驱动力进行研究。结果表明:①区域土地利用以敞水区为主。10年来,挺水植物群落、养殖塘和农田的面积呈增加趋势,敞水区和乔灌植物群落呈减少趋势; ②土地利用转入类型及面积大小依次为挺水植物群落(1 535.15 hm²),养殖塘(984.09 hm²)和乔灌植物群落(440.33 hm²); 土地利用转出类型及面积大小依次为敞水区的1 711.72 hm²、养殖塘的503.69 hm²和挺水植物群落的482.71 hm²; ③区域乔灌植物群落分布重心总体往西北方向偏移,向外湖方向扩张,挺水植物群落分布重心总体往东北方向偏移,向东部水流下游急剧扩张; 农田与养殖塘的扩张方向一致,由西部的老淤积滩向东部的新淤积滩扩散。由此可见,围垦养殖导致湿地景观破碎度增加,生态功能丧失加剧,今后亟待采取有效措施进行调控。

Spatial and temporal changes in wetland use in the meeting place of Hung-tse Lake and Huaihe River

The confluence area of Hung-tse Lake and Huaihe River is one of the most important wetland types, which is functionally serving as the particular biology resource reservoir and buffer zone. To understand the wetland evolution and the driving factors as well as changes of the land use in Laozishan town(118.454°-118.692°E,33.166°-33.188°N), a typical wetland was investigated at the intersection place of Hung-tse Lake and Huaihe River. The land use information was extracted from three sets of remote sensing images data(2003, 2008 and 2013)with high resolution and land use spatial distribution during the past 10 years. The spatial and temporal changes in the conversion of land use, variation tendency and driving factors were analyzed by GIS technique, transfer matrix and centroid method. The results showed: ①The open water dominated the regional land use. The areas of emergent plant, culture ponds and farmlands increased with time going while the areas of the open water, trees and shrubs decreased during the past 10 years. ②An area of 2 959.57 hm² open water has been converted as emergent plant(1 535.15 hm²), culture ponds(984.09 hm²)and trees and shrubs(440.33 hm²), respectively. In contrast, the areas of open water, culture ponds and emergent plant have increased to 1 711.72, 503.69 and 482.71 hm² during the period, respectively. ③The centroid of trees and shrubs in the region wholly extended to the open water in the northwest, while the distribution of the emergent plant shifted to the northeast, showing a rapid expansion to the downstream. Both farmlands and culture ponds have expanded from the western developed shoals to the eastern developing shoals. It could be concluded that culture ponds substantially lead to an increasing landscape fragment, thus threatening the ecological functions of the wetlands. It is very urgent for the wetland protection to conduct the potential countermeasures in the next activities.