中文摘要：

基于1982-2006年的AVHRR NDVI和2000-2013年的MODIS NDVI数据,通过数据一致性拟合建立了若尔盖高原的1982-2 013年NDVI长时间序列数据集,在此基础上运用像元二分模型计算得到若尔盖高原32年的逐月植被覆盖度。验证结果表明,平均绝对误差为10.51%,均方根误差为13.49%,R^2为0.62,具有较好的精度,说明遥感估算值合理可信。根据遥感计算得到的植被覆盖度,分析了若尔盖高原1982-2013年植被覆盖度的时空变化规律。若尔盖高原32年平均植被覆盖度为43.77%,在空间上表现出东部高、西部低的分布特征。1982-2013年期间若尔盖高原植被覆盖度整体上呈现上升趋势,平均变化速率为0.08%·a^（-1）,其中1982-2001年植被覆盖度呈较大幅度波动,但是没有明显的上升或者下降趋势,2001-2013年则呈现较明显的上升趋势。32年期间植被覆盖度年变化率的空间差异性显著,中心区域整体上呈现较低的上升趋势,而在大部分地区植被覆盖度显著上升和显著下降的区域交错分布。

英文摘要：

As a comprehensive quantitative indicator of vegetation cover conditions,vegetation fraction is one of the important parameters in meteorological and ecological models.Based on the AVHRR NDVI from 1982 to 2006 and MODIS NDVI from 2000 to 2013,the 32-year long-term monthly NDVI dataset in Zoige Plateau was generated by data consistency correction.Then the monthly vegetation fraction in the plateau was calculated using the dimidiate pixel mode.Validation result gives a satisfactory accuracy with a mean absolute error of 10.51%,a root mean square error of 13.49%,and a R~2 of 0.62.The spatial and temporal variations of vegetation fraction in the study area were analyzed.The 32-year averaged vegetation fraction in Zoige Plateau was 43.77%,showing a spatial tendency that high in the east and low in the west.From 1982 to 2013,the annual averaged vegetation fraction over Zoige exhibited an increasing tendency,with an annual rate of 0.08%.During the period of 1982 — 2001,vegetation fraction showed trendless fluctuations,and during the period of 2001 — 2013,vegetation fraction showed obvious increasing trend.The inter-annual trend of vegetation fraction over Zioge exhibited significant spatial heterogeneities.The central zone of the plateau generally showed increasing trends.However,in most of the study area,vegetation degradation regions and restoration regions were intricately interwoven.