Abstract: On the basis of assessing the ecological security for the five oases of the middle and lower Heiher River in the middle 1980s and at the beginning of 2000s, the paper analyzes the ecological security change of these oases. The integrated assessing results of the oases ecological security are reduced from the middle to the lower reaches of Heiher River in the middle 1980s and at the present. The present state of ecological security declines more than that of 1980s. The dropping range also increases from the middle to the lower reaches. Compared with those of 1980s, water security and land security drop obviously, but social economic security rises a little within the three subsystems. Under the background of macroscopical climate change, the cultivated land increases and oasis area enlargement in the middle reaches makes more imbalance between supply and demand of water resource, which has caused certain negative effect on the ecological environment of the oasis in lower reaches. And it is the very important reason that causes the oasis in the lower reaches diminishing, the oasis systematic area of the whole basin atrophying, and the stability declining. In order to realize the ecological security and sustainable development of the Heiher basin, it must strengthen allocation of the water resource in the whole basin and make basin comprehensive management.

Key words: ecological security, environment change, oasis, the middle and lower Heiher River

摘要： 在对黑河中下游5个绿洲1980s中期和2000s近期的状况开展生态安全评价的基础上，进行各个绿洲及流域的生态安全变化分析。无论是1980s中期还是近期，绿洲生态安全综合评价的结果均由中游向下游依次降低, 而近期的生态安全状况又比1980s中期有不同程度的下降，下降的幅度也是由中游向下游依次增大。在支持区域生态安全总系统的3个分系统中，与20世纪80年代中期相比，水安全和土地安全水平均明显下降，社会经济安全有所上升。在宏观气候变化的背景下，中游绿洲耕地的增加和绿洲面积的扩大使水资源供需矛盾更加突出，并对下游绿洲的生态环境造成了一定的负面影响，是导致下游绿洲萎缩，整个流域绿洲系统面积缩小、稳定性下降的重要原因。必须加强全流域水资源的调配和流域的综合管理，才能实现黑河流域的生态安全和可持续发展。

关键词: 生态安全, 环境变化, 绿洲, 黑河中下游