西南地区是我国重要的生态安全屏障区， 也是生态脆弱和气候敏感区。本文基于MOD13A3的NDVI数据集， 利用像元二分模型首先计算了西南五省市区2000 -2020年西南整体和分省市区年、 生长季和四季的平均植被覆盖度FVC（Fractional Vegetation Cover）， 并对不同时间尺度的FVC进行了时空变化特征分析， 然后利用ERA5的气温、 GPCP卫星降水和DEM等资料， 对过去21年影响西南地区FVC变化的主要影响因素进行了讨论， 最后利用Hurst指数对FVC的未来变化趋势进行了预测。结果表明： （1）2000 -2020 年以来， 西南地区东部FVC整体呈增加趋势， 尤其在重庆和贵州增加最快， 西藏地区总体呈下降趋势。（2） 西南地区FVC在空间上总体呈现东高西低的特点， 2000 -2020年平均FVC为0.46， 在年际空间变化上FVC的上升区域占西南地区总面积的43.9%， 下降区域占53.5%。（3）降水对FVC起促进作用， 气温在不同地区则表现出不同的影响。（4）人类活动对FVC的影响很大， 对植被的促进、 抑制和无影响区域分别占栅格百分比的40.4%、 47.6%和12.0%。（5）高程和不同时间尺度的FVC都显著相关， 但都呈现出极显著的下降趋势； 不同时间尺度的FVC随坡度增加都显著增加， 但当坡度大于25°后FVC会逐渐减小； 坡向对西南地区FVC的影响相较于坡度、 高程和气候因子的影响并不显著。（6）未来西藏、 西南地区东部的四川、 云南和贵州交界处的FVC整体将呈增加趋势， 而四川西部和横断山脉的大部分地区将呈减少趋势。研究结果能为西南地区生态保护方案的制定提供数据支撑和科学指导。

The southwestern China is a vital ecological safeguard and is characterized by ecological fragility and climate sensitivity.Based on the MOD13A3 NDVI dataset， this study used a pixel dichotomy model to calculate the average Fractional Vegetation Cover （FVC） from 2000 to 2020 annually， during growing seasons， and in each of the four seasons for the whole southwestern China and its provinces， a spatio-temporal variation analysis was then performed on FVC across different time scales.The study also discussed the primary factors influencing FVC changes over the past 21 years， using ERA5 temperature data， GPCP satellite precipitation data， and DEM data.Finally， the Hurst Index was used to predict future FVC trends.（1） The results indicate that from 2000 to 2020， the overall FVC in the eastern part of the southwestern China showed an increasing trend， particularly in Chongqing and Guizhou， while Tibet showed a general decline.（2） Spatially， the FVC generally showed a "higher in the east and lower in the west" trend， with areas where FVC increased accounting for 43.9% of the total area， and areas of decrease accounting for 53.5%.（3） Precipitation promotes FVC， while temperature has varied effects in different regions.（4） Human activity significantly impacts FVC， with promotion， suppression， and no effect zones accounting for 40.4%， 47.6%， and 12.0% of the grid percentage， respectively.（5） Elevation and FVC over different time scales are significantly correlated but both exhibit a pronounced declining trend.FVC increases significantly with slope， but decreases when the slope is greater than 25°.The effect of aspect on FVC in the southwestern China is less significant than that of slope， elevation， and climatic factors.（6） In the future， the FVC in Tibet and the eastern parts of Sichuan， Yunnan， and Guizhou in the southwestern China will increase， while most areas of western Sichuan and the Hengduan Mountains will exhibit a decreasing trend.The results can provide data support and scientific guidance for the formulation of ecological protection plans in the southwestern China.