Dominated by an arid and semiarid continental climate, the Beijing-Tianjin Sandstorm Source Region (BTSSR) is a typical ecologically fragile region with frequently occurring droughts. To provide information for regional vegetation protection and drought prevention, we assessed the relations between vegetation cover change (measured by the Normalized Difference Vegetation Index, NDVI) and the Standardized Precipitation Evapotranspiration Index (SPEI) at different time-scales, in different growth stages, in different subregions and for different vegetation types based on the Pearson’s correlation coefficient in the BTSSR from 2000 to 2017. Results showed that 88.19% of the vegetated areas experienced increased NDVI in the growing season; 48.3% of the vegetated areas experienced significantly increased NDVI (P < 0.05) and were mainly in the south of the BTSSR. During the growing season, a wetter climate contributed to the increased vegetation cover from 2000 to 2017, and NDVI anomalies were closely related to SPEI. The maximum correlation coefficient in the growing season (Rmax) was significantly positive (P < 0.05) in 97.84% of the total vegetated areas. In the vegetated areas with significantly positive Rmax, pixels with short time-scales (1–3 mon) accounted for the largest proportion (33.9%). The sensitivity of vegetation to the impact of drought rose first and then decreased in the growing season, with a peak in July. Compared with two subregions in the south, subregions in the north of the BTSSR were more sensitive to the impacts of drought variations, especially in the Xilingol Plateau and Wuzhumuqin Basin. All four major vegetation types were sensitive to the effects of drought variations, especially grasslands. The time-scales of the most impacting droughts varied with growth stages, regions, and vegetation types. These results can help us understand the relations between vegetation and droughts, which are important for ecological restoration and drought prevention.

京津沙尘暴源地区（BTSSR）以干旱和半干旱的大陆性气候为主，是典型的生态脆弱地区，经常发生干旱。为了为区域植被保护和干旱防御提供信息，我们评估了在不同时间段，不同生长阶段的植被覆盖度变化（通过归一化植被指数，NDVI衡量）和标准化降水蒸散指数（SPEI）之间的关系，根据2000年至2017年BTSSR中皮尔森相关系数，在不同分区和不同植被类型上进行研究。结果表明，有88.19％的植被在生长季节经历了NDVI的增加；48.3％的植被区的NDVI显着增加（P<0.05），并且主要位于BTSSR的南部。在生长季节中，气候变湿导致2000年至2017年植被覆盖率增加，并且NDVI异常与SPEI密切相关。生长季节的最大相关系数（Rmax）显着为正（P<0.05），占植被总面积的97.84％。在Rmax明显为正的植被区中，时间尺度较短（1-3个星期一）的像素占最大比例（33.9％）。植被对干旱影响的敏感度在生长季节先上升，然后下降，7月达到顶峰。与南部的两个分区相比，BTSSR北部的分区对干旱变化的影响更为敏感，特别是在锡林郭勒高原和乌竹木琴盆地。所有四种主要的植被类型都对干旱变化的影响敏感，尤其是草地。影响最严重的干旱的时标随生长期，地区和植被类型的不同而变化。这些结果可以帮助我们了解植被与干旱之间的关系，