新疆焉耆盆地绿洲景观的空间格局及其变化

通过GIS技术的叠加和提取功能建立了焉耆盆地两个时间段的景观类型转移矩阵。在此基础上,分析了焉耆盆地内部绿洲景观类型的动态演化过程和空间分布特征。结果表明:焉耆盆地经过近40年的土地开垦后,人工绿洲呈现出上升的趋势,农田向自然绿洲和荒漠的扩张在整个研究阶段均可见;农田开垦的对象表现为从草地(含部分沼泽地)→多汁木本盐柴类荒漠→超旱生灌木半灌木荒漠迁移,体现了农田绿洲开垦从易到难,自然绿洲不断缩小,人工绿洲不断扩大的过程;对土地和水资源的不合理利用,导致盆地内湖泊水体、湖泊周边及农田绿洲出现明显的生态退化。焉耆盆地今后的规划和发展必须高度重视人工绿洲生态系统和自然生态之间的平衡,盆地环境治理很大程度决定于水资源的合理利用和合理调节。

Spatial pattern and evolution of oases in the Yanqi Basin,Xinjiang

The Bosten Lake,located in the Yanqi Basin,is the largest freshwater lake in China.It is not only the end of the Kaidu River,but also the headstream of the Peacock River,supplying water to the Tarim River and the Tarim Oil Field Base so far. Studies in the past usually focused on the change of water surface and water quality of the lake,seldom on the landscape pattern of the Yanqi Basin using integrated synthetic methods.The landscape pattern and its dynamics of the Basin directly control the distribution and dynamic changes of substance,energy and species,so study of the landscape pattern and its dynamics is necessary. By overlapping and extracting functions with GIS,two conversional matrixes of landscape in the Yanqi Basin were built.Based on two transitional matrixes of landscape,the landscape pattern and dynamics of the Yanqi Basin were analyzed.The results show that after 40 years land reclamation,the artificial oasis presented a trend of expansion in the Yanqi Basin.It is clearly discernible that farmland expanded to the fringe of the transitional zone between farmland and the natural oasis;the model of transition of farmland is from grassland to halophyte hungriness to xenophiles' hungriness,an indication of the process of reclamation of farmland from easy to difficult,i.e.,the constant shrinkage of the natural oasis and the expansion of the artificial oasis.The development of oasis is associatied with the distribution of water resources,when water resource is short,the process of desertification occurs,contrariwise,the process of salinization occurs.Because of the irrational use of the land and water resources,apparent ecological degeneration occurs in the lake water,peripheries of the lake and the oasis farmland in the Basin.For future sustainable development in the Yanqi Basin,attention should be paid to the ecosystem balance between artificial oasis and natural oasis.The management of the oasis eco-environment depends to a greater extent on the regulation of water resources and the rational use of land.