雅鲁藏布江流域气候条件复杂，生态环境极为脆弱。在全球气候变化背景下，雅鲁藏布江流域陆地生态系统的演变直接关系到区域生态安全屏障功能,对保障流域内水资源安全、生态环境平衡及促进区域可持续发展也具有至关重要的意义。 本研究以雅鲁藏布江流域为研究对象，基于生长季归一化植被指数（Normalized Difference Vegetation Index，NDVI）分析了流域植被时空演变规律；利用MODIS（Moderate Resolution Imaging Spectroradiometer）遥感数据验证了LPJ（Lund-Potsdam-Jena）植被动态模型在雅鲁藏布江流域的适用性，在此基础上，模拟了研究区陆地生态系统基于蒸散发（Evapotranspiration，ET）和净生态系统生产力（Net Ecosystem Productivity，NEP）两个指标的演变规律；构建了三种气候变化情景，分析气温升高1℃、2℃和3℃对研究区陆地生态系统ET和NEP变化的影响，并揭示气候变化背景下雅鲁藏布江流域陆地生态系统水循环和碳循环演变规律。 本研究的主要成果与结论有：（1）雅鲁藏布江流域生长季NDVI自上游至下游逐渐增大。生长季NDVI呈现显著增加和降低的区域分别占22.64%和3.98%，米拉山东侧的大片区域呈现显著增加趋势。与降水呈现显著正相关的区域主要分布在拉孜和羊村水文站之间的河谷地带；与气温呈现显著正相关的区域主要分布在米拉山区域以及上游的部分区域。（2）经与MODIS遥感数据ET的对比分析发现，LPJ植被动态模型模拟结果的合理性得到了检验。模型模拟结果显示：年平均ET时间序列呈现极不显著增大趋势，但有70.8%的网格的ET时间序列呈现显著增大趋势；年平均NEP时间序列呈现显著增大趋势，研究时段内主要表现为碳汇，尤其是20世纪90年代，且有73.0%的网格处于碳汇状态。除雅鲁藏布大峡谷外，流域内碳源区释放CO2的量增加，而碳汇区固碳量也增加。（3）气候变化情景下，模型模拟结果显示：气候变化时段内多年平均ET处于高值区间内的分布面积随着气温升幅的增加而增大，且分布位置向西扩张以及从流域干支流河谷地带向周围扩张。ET变幅处于高值区间内的分布面积也随着气温升幅的增加而增大，尤其表现在米拉山地区；多年平均NEP及其变幅处于高值区间内的分布面积随着气温升幅的增加而增大，碳汇区固碳强度逐渐增强，主要表现在米拉山地区。而且，NEP及其变幅处于低值区间内的分布面积也逐渐增加，碳源区释放CO2的强度也逐渐增强，主要表现在流域干支流的河谷地带。

The Yarlung Zangbo River Basin (YZRB) has complex climate conditions and is extremely fragile in its ecological environment. Under the background of global climate change, the evolution of the terrestrial ecosystem in the YZRB would directly influence the founction of regional safety barriers, which is also of vital importance to safeguard water resources security, balance and ecological environment, and promate regional sustainable development in this basin. The YZRB is selected as the research object, and the temporal and spatial evolution of vegetation in this basin are explored based on the Normalized Difference Vegetation Index (NDVI). Using Moderate Resolution Imaging Spectroradiometer (MODIS) data validates the applicability of the Lund-Potsdam-Jena (LPJ) vegetation dynamic model in the YZRB. Based on this model, the evolution rules based on Evapotranspiration (ET) and Net Ecosystem Productivity (NEP) in this study area were simulated. Then three scenarios of climate change were constructed, and we analyzd the effects of temperature increasing 1℃, 2℃ and 3℃ on the changes of ET and NEP in the terrestrial ecosystem of the YZRB, which also reveals the evolution of water cycle and carbon cycle of the terrestrial ecosystem under the background of climate change. The main results and conclusions of this study are: (1) The growing season NDVI has been found to increase greatly from the upstream to the downstream in the YZRB. The areas with significant upward and downward trend in growing season NDVI accounted for 22.64% and 3.98%, respectively. Large areas in the east of Mila Mountain showed a significant upward trend. The areas with significant positive correlation with precipitation were mainly distributed in the valleys between the Lahu and Yangcun hydrological stations, and areas that are significantly positively correlated with temperature were mainly distributed in the Mila Mountain area and some areas in the upstream. (2) Compared with MODIS ET data, the rationality of simulation results of LPJ vegetation dynamic model is verified. The simulation results show that the annual average ET showed a very insignificant upward trend, but the areas with significant upward trend accounted for 70.8%. The annual average NEP showed a significant upward trend, and the ecosystem was expressed as a crabon sink in the research period, especially in the 1990s. The areas expressed as carbon sink accounted for 70.8%. In addition to the Yarlung Zangbo Grand Canyon area, the amount of CO2 released in the carbon source area of this basin increased, and the carbon sequestration in the carbon sink area increased. (3) Under climate change period, The simulation results show that the distribution area of multi-year average in high value ranges during the climate change period showed an upward trend with the increase of temperature increases, and the distribution location expanded to the west and also expanded from the valley area of mainstream and its tributary to the surrounding area. The distribution area of ET in high value ranges showed an upward trend, especially in Mila Mountain area. The distribution area of multi-year average NEP and its variations in high value ranges also showed an upward trend with the increase of temperature increases, and the carbon sequestration in the carbon sink area increased, mainly in the Mila Mountain area. What’s more, the distribution area of multi-year average NEP and its variations in low value ranges explicated an upward trend, the amount of CO2 released in the carbon source area increased, mainly in the valley of mainstream and its tributary.