摘要:归一化植被指数NDVI可有效表征植被生长信息，其中，长时间序列NDVI在分析全球和局部植被变化扮演重要角色。利用Google Earth Engine提供的全系列Landsat卫星数据，应用LandTrendr时间序列分割算法，讨论了雅鲁藏布江区域植被覆盖变化特征，并对植被变化模式进行判别。研究结果表明：1985-2018年间雅鲁藏布江流域，（1）NDVI总体呈现上升趋势，仅在局部区域出现下降，自上游至下游NDVI变化强度逐渐增加，1986-1990年NDVI变化最为剧烈，1991-2000年次之，2001-2017年NDVI变化强度逐渐减弱；（2）NDVI干扰变化95%集中在0-0.42之间，平均干扰时间4.96年；NDVI恢复变化95%集中在0-0.4之间，平均恢复时间12.55年；（3）NDVI干扰模式主要以持续下降为主，但2000年前的下降速率小于2000年后的下降速率；NDVI恢复模式以持续上升为主，但2000年前的上升速率大于2000年后的上升速率。



Abstract:Information on vegetation growth can be effectively characterized by the Normalized Difference Vegetation Index (NDVI), in which the long-term NDVI plays a significant role in analyzing global and local vegetation change patterns. The major purpose of this study is to elucidate the characteristics of vegetation coverage changes in the Yarlung Zangbo River Basin, and detect the vegetation pattern changes with a series of Landsat satellite data from Google Earth Engine, applying the LandTrendr time series segmentation algorithm. The results indicated that from 1985 to 2018, (1) with only few regional declines, the overall NDVI showed an upward trend. The intensity of NDVI change increases gradually from upstream to downstream, with the most significant change between 1986 to 1990 and less significant change between 2001 to 2017. (2) 95% of the NDVI disturbance ranged between 0 and 0.42 and the average duration of the disturbance was 4.96 years. 95% of the NDVI recovery changed between 0 and 0.4 and the average duration of the recovery was 12.55 years. (3) The disturbance event had a declined NDVI and the decline rate before 2000 was slower than the decline rate after 2000. The recovery event had an increased NDVI and the increase rate before 2000 was faster than the increase rate after 2000.





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