塔里木河下游土地利用/覆盖变化环境效应

利用 1988和 2 0 0 0年Landsat 5的 4、3、2 (RGB)波段合成影像解译结果 ,采用中国科学院资源环境数据库中的全国 1∶10 0 0 0 0土地资源利用分类系统 ,基于GIS(Arc/info 7.1)对塔里木河下游近 12a来土地利用 /覆被变化进行了研究 ,在此基础上研究了生态环境效应。结果表明 ,(1) 2 0 0 0年研究区土地利用以未利用地和草地为主 ;(2 )景观格局指数表明 :多样性指数在增加 ,景观破碎度均在 0 .2以下 ,说明景观连通性高 ,抗逆性强 ;疏林地分维数值最大 ,说明其空间形状较简单 ,廊道效应较低 ;景观基质是沙地 ,且沙漠化在进一步加强 ;(3) 1988- 2 0 0 0年 ,耕地、水域、未利用地和城镇用地有所增加 ,而林地和草地则在减少 ;(4) 12a间 ,未发生转化的土地占 99.6 5 % ,发生转化的仅 0 .36 %。其中 ,改善类土地面积大于退化类土地 ,开发类土地净增长面积也大于同期弃耕类土地 ;(5 )研究区LUCC除受暖温带大陆性干旱气候的影响外 ,人类活动改变地表水的地域分配及对天然植被的破坏 ,则是引起生态环境退化的主要原因。

The Land Use/Cover Changes and the Eco-environmental Responses in the Lower Reaches of Tarim River,Xinjiang

Taking two composite Landsat 5 TM (thematic mapper) images of band 4, 3 and 2 taken in 1988 and 2000 respectively as the data sources, this paper carries out the study on the land use/cover changes in the lower reaches of Tarim River in recent 12 years by using the information about the land use and land cover interpreted from these two images based on the classification system of land use (1:100 000) of the Resources and Environment Database of Chinese Academy of Sciences, and the eco-environmental responses in this area are also researched. The results are as follows: (1) The land use in 2000 was dominated by the unused lands and grasslands. (2) The landscape pattern indexes show that the diversity was increased. The values of fragmentation in the typical regions were less than 0.2. Such a low fragmentation reveals that the landscape connectivity was high and the resistant capability to environment change was strong. The fractal dimension of the sparse woodlands was the highest, which reveals that the shape of every patch was relative simple, the effects of corridors were small, the matrix of landscapes was sandy lands, and the desertification became more serious. (3) During the period from 1988 to 2000, the areas of farmlands, waters, unused lands and urban lands were enlarged but the areas of woodlands and grasslands were reduced. (4) In recent 12 years, the area of unchanged lands occupied 99.645% of the total land area but the area of changed lands occupied 0.355% only, in which the area of the improved lands was larger than that of the degraded lands, and the area of the developed lands was larger than that of the lands discarded from cultivation. (5) Except the land use and land cover in the study area are affected by the warm-temperate continental arid climate, human activities (such as changing the spatial distribution of surface water and destroying the natural vegetation) are the main causes resulting in the degeneration of the eco-environment. The eco-environment responses include the increase of mineralization, drawdown of groundwater level, degeneration of the forests of Populus euphratica, shrubbery and grasslands, enlargement of the area of desertified lands, etc.