2001—2020年黄河流域植被覆盖变化及其影响因素

基于MODIS NDVI植被指数和气象数据集，以集合经验模态分解、趋势分析和随机森林回归分析等方法，分析了黄河流域2001—2020年植被覆盖时空变化特征，并对其气候驱动因素进行探讨。结果表明：（1）2001—2020年黄河流域植被覆盖整体呈显著增长趋势，增速为0.055/10a （P<0.05），2010年之前增速（0.067/10a）大于2010年之后的增速（0.051/10a）。（2）空间上，植被覆盖增加区域主要分布在陕北黄土高原、甘肃省东南部、内蒙古自治区河套平原等退耕还林还草生态工程实施区域，而植被覆盖显著下降区域则集中在关中平原城市群、黄淮海平原以及青藏高原等区域。（3）气温、降水和CO₂浓度等对黄河流域植被生长起到正向促进作用，且绝对敏感性依次降低，而大气饱和水汽压差、太阳辐射等对植被生长起到抑制作用。本研究结果可为评估气候变化对黄河流域植被覆盖变化的综合影响提供参考依据。

Changes in vegetation coverage and its influencing factors across the Yellow River Basin during 2001-2020

Based on the MODIS NDVI vegetation index and meteorological data sets， and by utilizing the methods of Ensemble Empirical Mode Decomposition， trend analysis， and Random Forest Regression， this paper analyzes the spatiotemporal changes in vegetation coverage in the Yellow River Basin from 2001 to 2020 and discusses the driving factors behind the changes. The analysis produced the following findings. （1） The spatial averaged NDVI showed a significant increasing trend across the Yellow River Basin from 2001 to 2020， with a growth rate of 0.055/10a （P<0.05）. The regional growth rates of different land cover types are significantly different. Among them， the growth rate of the conversion of farmland to forest （grass） region is the fastest， followed by the agricultural land region， and the natural vegetation region. （2） Spatially， areas with increased vegetation coverage are mainly distributed in the Loess Plateau of northern Shaanxi， southeastern Gansu Province， the Hetao Plain of Inner Mongolia Autonomous Region， and in other areas where the Sloping Land Conversion Program is implemented. Meanwhile， areas with significant decline in vegetation coverage are mainly concentrated in the Guanzhong Plain urban agglomerations， the Huanghuaihai Plain， and the Qinghai-Tibet Plateau. （3） Regression analysis results show that the overall impact factors such as temperature， carbon dioxide concentration， and precipitation positively promote vegetation growth and the absolute contribution rate will decrease sequentially， while factors such as atmospheric vapor pressure deficit and radiation generally inhibit vegetation growth. The findings of this study provide a reference for assessing the comprehensive impact of climate change on vegetation cover changes across the Yellow River Basin.