洞庭湖集成垸退田还湖前后景观格局变化和生态安全格局

Change of Landscape Patterns before and after the Land Conversion for Restoration in Dongting Lake Region and its Ecological Safety

以集成垸为研究对象,分析双退垸退田还湖前后景观格局变化,并设计了双退垸的生态安全格局。结果表明,集成垸双退以后,其本底由农作物变为杨树,旱地面积大量减少,建筑面积减少,但幼林面积大量增加,芦苇面积增加。由于退田还湖的实施,芦苇类和旱地景观空间结构变得更复杂,而成林、幼林和建筑景观空间结构变得更简单。退田还湖后,集成垸逐渐从小斑块、多种景观要素类型共同控制的景观格局向以大斑块、类型较单一的景观格局演变。借助已有研究成果,按照垸内土地的高程分布设计各类人工植被的经营目标和分布地段,形成既能蓄洪又有一定经济效益和生态效益的双退垸最佳生态安全格局。

A typical abandoned farmland surrounded by dykes were selected in Dongting Lake Region, the landscape patterns were compared before and after the land conversion from crop cultivation to lake wetland, and the ecological safety of the reclaimed land were described in this paper. Results showed that the cultivated land were changed from cropping to tree plantations from 1993 to 2004, and the total area of cropping and building construction decreased greatly while the area of poplar plantations and common reeds increased sharply. Since the launch of land conversion project in 1998, spatial structures of common reeds and cropping land have become complicated while those of the plantations and buildings become simplified. Meanwhile, the whole landscape pattern has been changed from small and variable patches to large and less variable patches. Based on the height of different land types in the study area, different management purposes and deployment patterns of poplar plantations and common reeds were designed to produce an optimal ecological safety with functions of not only floodcontainment, but also economic benefit and ecological benefit. According to the design, 12.95km^2 of land will be used for ecological protection and timber plantation, 3.06km^2 for fast-growing plantations, 9.04km^2 for timber plantations, and 5.63km^2 for common reed farming.