西北干旱区黑河下游植被覆盖变化研究综述

植被作为干旱区敏感的环境要素， 能直观反映自然环境状况， 任何植被覆盖变化都可揭 示区域环境状况的演化与变迁。因此， 植被覆盖变化研究已成为揭示干旱区自然环境变化及其规 律的重要手段。本文针对干旱区黑河下游这一特殊地域及其植被生态系统存在的问题， 综述了植 被覆盖变化及与其密切相关的地下水、土壤水盐平衡、全球气候变化和人类活动等因素的关系， 目的是全面分析与植被覆盖变化相关的各因素， 为分析植被覆盖变化机理及进一步研究黑河下 游生态环境演变服务。最后总结了目前黑河下游植被覆盖变化研究中存在的问题， 并提出了相应 的解决策略， 为区域植被覆盖变化研究提供了参考依据。

Review of Study on Vegetation Cover Change in the Lower Reaches of Heihe River in Nor thwest Ar id Ar ea

In arid areas, vegetation can reflect the status of environment directly as a sensitive element of environment; and the vegetation cover changes can represent evolvement and variance of the environment. So, the study of vegetation cover changes becomes an important instrument to open out the changes of environment and their laws in arid area. This paper is aimed at a special region of the lower reaches of Heihe River and the problems with its ecosystem of vegetation, discussing synthetically the vegetation cover changes and the elements related, such as the groundwater, the balance of soil water - salt, global climatic changes and human activities. The aim is to analyze the mechanism of vegetation cover changes exactly by analyzing correlative factors with vegetation cover changes extensively, and to provide supports for the study of environmental evolvement of the lower reaches of Heihe River. Finally, this paper summarizes existent questions in the study of vegetation cover changes, and puts forward relevant strategy to resolve them, providing references for the study of vegetation cover changes in the lower reaches of Heihe River.