近35年来老哈河流域湿地关键区景观格局演变及其驱动力

Landscape pattern evolution of wetland critical areas in Laoha River basin and driving forces in recent 35 years

湿地生态系统在干旱区、半干旱区的作用远高于湿润区,在调节气候、涵养水源、水体净化、保护生物多样性方面发挥的作用更为显著。近年来,老哈河流域部分河段断流、水域面积减小、湿地萎缩、植被生态功能退化、生物多样性衰减等生态环境问题日益凸显,对流域生态系统和经济可持续发展造成威胁。利用1985年、1995年、2006年、2015年和2019年5期遥感影像解译了研究区土地覆被类型,利用1985-2019年35期遥感影像解译了研究区内红山水库的水域面积,运用矩阵转移法、景观格局指数、相关分析、主成分分析等方法,分析了老哈河流域湿地关键区土地覆被类型时空特征,以及湿地景观格局演变及其驱动力。结果表明:1)近35年来老哈河流域湿地关键区湿地总面积减少了近2/3,呈显著减少趋势,特别是1995-2006年面积减少达77.21km2,河漫滩地基本消失殆尽,湿地大部分转化成了旱田。2)沼泽湿地和水域变得简单而集中,河漫滩地变得分散且破碎化严重,水田面积增大但连通性差,景观多样性指数和均匀度指数均呈显著减小趋势,斑块的多样化和均匀性程度逐渐降低,景观蔓延度指数呈显著增加趋势,越来越受优势景观类型控制。3)人类活动是老哈河流域湿地关键区湿地萎缩的关键因素,与社会经济和农业发展过程中对水资源利用加剧密切相关。

The role of wetland ecosystem in arid and semi-arid regions is much critical than that in humid regions, especially in regulating climate, water conservation and purification, and biodiversity. In recent years, some ecological and environmental problems such as dry-flow, reduction of water area, shrinking of wetlands, degradation of vegetation ecological function, and decline of biodiversity in the Laoha River basin have become increasingly prominent, posing threats to the basin’s ecosystem and economic sustainable development. By using five remote sensing images from 1985 to 2019, matrix transfer method, landscape pattern index, correlation analysis, principal component analysis and other methods, the temporal and spatial characteristics of land cover types in critical areas of wetland in the Laoha River basin, as well as the evolution of wetland landscape pattern and its driving forces were analyzed. The results showed: 1) In the past 35 years, the total area of wetlands in the Laoha river basin has reduced by nearly 2/3, showing a significant reduction trend, especially from 1995 to 2006, the area decreased by 77.21 km2. The floodplain land has basically disappeared, and most of the wetland has been converted into dry land. 2) In the study area, the swamp wetland and waters became simple and concentrated, and the flood plain became scattered and seriously fragmented, paddy field area increased but their connectivity was poor. Both the landscape diversity index and the evenness index showed significant decreasing trends, the diversity and uniformity of the patches gradually decreased as well. The landscape sprawl index showed a significant increase, and it was increasingly controlled by dominant landscape types. 3) Human activities is the key factor of wetland shrinkage in Laoha River basin, which is closely related to the intensification of water resources utilization in the process of social economy and agricultural development.