基于遥感的贺兰山两侧沙漠边缘带植被覆盖演变及对气候响应

RS-based study on the change of vegetation cover and its response to climate change in two desert marginal zones at both sides of the Helan Mountain

使用NOAA/AVHRR 8KM 1981-2001数据,以及准同期逐日观测气象数据,用GIS与RS空间分析方法和数理统计的分析方法对数据进行了归纳和插值处理。对贺兰山东西两侧腾格里与毛乌素两大沙漠的南缘带植被覆盖、气候要素的降水与气温变化特征以及它们之间的响应关系进行了分析。通过比较得出不同干湿条件沙漠边缘带植被覆盖状态变化的差异,以及各自生境对气候变化的响应特征。研究表明:气候条件中水分条件是决定干旱区与半干旱区土地覆盖状态的关键性因素;但是地形条件对植被覆盖的季相差异的影响也不可忽视;与植被覆盖相比,低覆盖植被分布面积的变化可以更好的揭示生态环境对气候变化的响应;整个研究期气候整体趋于暖干化,暖干程度在1999-2000年达到了高峰,随之植被覆盖在2000-2001年达到了最低值。这说明生态环境对气候变化的响应存在一种时间上的滞后性。从RS与GIS角度为干旱区与半干旱区沙漠边缘带宏观土地覆盖变化研究提供了一种较为可靠方法,为因地制宜进行生态环境综合治理与防治土地沙漠化也提供一种新的参考。

The data used in this study are concluded and processed with interpolation using RS image processing software Erdas, GIS software- Arc/Info and database software FoxPro. This paper analyzes the vegetation cover and the change characteristics of climatic factors, such as precipitation and air temperature, and their mutual response relations in the Tengger Desert and Mu Us Desert located at both sides of the Helan Mountain. The differences in the change characteristic of vegetation cover in the marginal zones of the two deserts with different moisture conditions and the responses of their habitats to climate change are compared. The study reveals that, among the climatic factors, the moisture conditions is the key factor affecting the vegetation cover in arid and semiarid regions, and the effects of terrains on seasonal change of vegetation cover are also important. The data of the change of area of low - coverage vegetation can be used to reveal the response of ecological environment to climate change. During the whole study period, the warmingdrying trend of climate change continued and to its maximum during the period of 1999 -2000, thus the vegetation coverage was reduced to its minimum during the period of 2000 -2001. These reveal that there is a temporal hysteresis in the response of ecological environment to climate change. The study provides a reliable RS- and GIS- based method of researching the macroscopic change of land cover in the desert marginal zones in arid and semiarid regions, and also the references for improving ecological environment and controlling land desertification.