准格尔旗植被覆盖度变化的时间序列遥感监测

准格尔旗2000年开始实施退耕还林、沙漠治理政策已逾10年,了解准格尔旗植被恢复现状及存在的问题,对于制定更加合理的环境治理政策、实现环境和经济的可持续发展具有重要意义1]。本研究基于准格尔旗地区1990、2000和2011年3个时间序列的Landsat TM/ETM+遥感影像,通过选取3个时期植被与裸地的NDVI值,代入像元二分法模型中,反演得到3个时期的植被覆盖度,并且通过研究准格尔旗3期植被覆盖度的时空变化特征、近21年的准格尔旗植被覆盖度转移矩阵、植被恢复/退化状况及驱动力,定量分析了该地区近21年植被覆盖度的时序变化和空间分布特征。研究结果表明:准格尔旗近21年植被覆盖度显著增加,平均覆盖度由1990年的15.53%上升到2000年的17.82%,以及2011年的29.30%;准格尔旗的大部分区域植被呈恢复状态,局部区域呈现退化现象;准格尔旗的植被覆盖度变化特征受降雨因素影响不显著,准格尔旗近21年植被覆盖度的显著提高主要得益于2000年之后的一系列植被恢复工程。

Analysis of Vegetation Fractional Cover in Jungar Banner Based on Time-series Remote Sensing Data

It has been more than 10 years since Jungar Banner began to apply the policies of forest implement and desertification control. It is important to understand the condition of vegetation recovery, so as to make more proper environment management policies and achieve sustainable economic development in the future. In this pa-per, we chose Landsat thematic mapper/enhanced thematic mapper plus（TM/ETM ＋） data in 1990, 2000 and 2011 to derive the vegetation fractional cover in Jungar Banner. And through image analyzing and processing, we got the NDVI values of pure vegetation and pure soil in such three periods. Then we got the vegetation frac-tional cover distribution maps in 1990, 2000 and 2011 by conducting the pixel dichotomy model. At last we ana-lyzed the temporal and spatial changes of vegetation fractional cover, such as the transfer matrixes, the vegeta-tion restoration/degradation and the driving forces which lead to such changes. Through quantitative analysis, we reached the conclusions that： in the past 21 years, the mean vegetation fractional cover of Jungar Banner has been improved from 15.53% in 1990 to 17.82% in 2000 and to 29.30% in 2011. Most area of Jungar Banner shows the phenomena of vegetation recovery, and the vegetation restoration phenomena is much more obvious from 2000 to 2011, i.e., from 1990 to 2000, 63.06% of the total area shows vegetation restoration phenomena, while from 2000 to 2010, 84.53% of the total area shows vegetation restoration phenomena. The driving forces analysis shows that the changes of vegetation fractional cover in Jungar Banner don＇t have significant correlation with the rainfall factor, while the changes have a significant correlation with afforestation projects which have been conducted since 2000.