贺兰山是中国荒漠和荒漠草原分界线，其东麓洪积扇上分布荒漠草原，在维持生态系统稳定性方面发挥着积极作用。本文研究了其植被覆盖度（Fraction Vegetation Coverage， FVC）时空变化，分析影响植被盖度变化的主要因子。利用Landsat卫星遥感数据，基于像元二分模型反演了2001—2020年贺兰山东麓洪积扇区荒漠草原植被覆盖度，分析其空间格局和时空变化特征，采用Sen+Mann-Kendall趋势分析、Hurst指数和参数最优地理探测器模型对其驱动因素进行分析。结果表明：（1）FVC空间上呈现出西北高东南低的趋势，以极低植被覆盖度和低植被覆盖度为主。多年FVC均值为33.38%，总体植被覆盖度处于较低水平。（2）2001—2020年FVC呈现显著增加趋势（P<0.01），年均增长率为2.34%，整体表现为西北部和东南部呈改善趋势，改善的区域占植被覆盖总面积的93.24%；植被覆盖度的平均变异系数为0.394，整体相对稳定，空间上东部和中部变化表现最为剧烈，具有显著的空间差异。（3）研究区植被覆盖度的反持续性较强，Hurst指数平均值为0.495，大于0.5的区域占44.77%；从空间分布上看，研究区南部、西部Hurst指数较高，植被变化的持续性较高，东部、北部Hurst指数较低，植被变化的持续性较低。（4）年降水量和土地利用类型是影响贺兰山东麓洪积扇区荒漠草原植被覆盖度空间分布的主要因子，交互探测表明年降水量、海拔、日照时数和空气湿度的交互作用Q值最大，水热因子组合对植被盖度影响增强显著；风险探测表明各驱动因子对研究区植被生长的影响均有其适宜的范围。本研究有助于揭示不同因子对贺兰山东麓洪积扇区荒漠草原植被变化的驱动机制。

Helan Mountain is the boundary between deserts and desert grasslands in China. Desert grasslands are distributed on the alluvial fan at its eastern foot， playing a positive role in maintaining ecosystem stability. Research is conducted on the spatiotemporal changes in fraction vegetation coverage （FVC）， and the main factors affecting vegetation coverage changes are analyzed. This study utilized Landsat satellite remote sensing data and inverted the vegetation coverage of desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountains from 2001 to 2020 based on a pixel binary model. The spatial pattern and spatiotemporal variation characteristics were analyzed， and the driving factors were analyzed using Sen+Mann Kendall trend analysis， Hurst index， and parameter optimal geographic detector model. The results indicate that： （1） FVC shows a trend of "higher in the northwest and lower in the southeast" in space， mainly characterized by extremely low vegetation coverage and low vegetation coverage. The average annual FVC is 33.38%， and the overall vegetation coverage is at a relatively low level. （2） From 2001 to 2020， FVC showed a significant increase trend （P<0.01）， with an average annual growth rate of 0.25%. Overall， the northwest and southeast showed an improvement trend， with the improved area accounting for 93.24% of the total vegetation coverage area； The average coefficient of variation of vegetation coverage is 0.394， which is relatively stable overall. The eastern and central regions show the most drastic changes in space， with significant spatial differences. （3） The anti sustainability of vegetation coverage in the study area is strong， with an average Hurst index of 0.495， and 44.77% of the areas are greater than 0.5； From a spatial distribution perspective， the Hurst index is higher in the southern and western parts of the study area， indicating a higher sustainability of vegetation change， while the Hurst index is lower in the eastern and northern parts， indicating a lower sustainability of vegetation change. （4） The annual precipitation and land use type are the main factors affecting the spatial distribution of vegetation coverage in desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountain. The interaction detection table shows that the impact of next year's precipitation on vegetation coverage is enhanced after the superposition of other factors， while the impact of topography and slope orientation on vegetation coverage is significantly enhanced； Risk detection indicates that each driving factor has an appropriate range of impacts on vegetation growth in the study area. This study helps to reveal the driving mechanisms of different factors on vegetation changes in desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountains.