College of Geomatics, Xi'an University of Science and Technology, Xi'an 710054, China.
Int J Environ Res Public Health. 2022 Mar 31;19(7):4180. doi: 10.3390/ijerph19074180.
The frequency and intensity of droughts are increasing in many parts of the world as a result of global climate change and human activity, posing a serious threat to regional ecological security. The climate in the middle reaches of the Yellow River Basin (MRYRB) has been warm and dry in recent years, with frequent droughts. In order to investigate the temporal trend of drought, and reveal the resistance of vegetation to drought in the MRYRB, this study used remotely-sensed vegetation index products (MODIS-NDVI and SPOT-NDVI) and the standardized precipitation evapotranspiration index (SPEI). The results indicated that: (1) drought intensity showed a weak upward trend in the study area from 2000 to 2018, with linear growth rates of SPEI at temporal scales of 1, 3, 6, 9 and 12 months of -0.002, 0.0034, 0.0198, 0.0234, and 0.0249, respectively; (2) drought was positively correlated with vegetation in most areas (97.6%), and vegetation was most affected by drought on long-term time scales (9 and 12 months); (3) with the extension of drought, vegetation resistance index decreased, then gradually recovered after the end of the drought. Forest had the longest resistance duration of 260 days, while grassland and cultivated land had resistance durations of only 170 days. This study adds to the understanding of vegetation's ability to withstand drought, and these findings provide evidence to support drought response in the MRYRB.
由于全球气候变化和人类活动的影响，世界许多地区的干旱频率和强度正在增加，对区域生态安全构成了严重威胁。近年来，黄河中游流域（MRYRB）气候温暖干燥，干旱频繁。为了研究干旱的时间趋势，揭示 MRYRB 植被对干旱的抵抗力，本研究使用了遥感植被指数产品（MODIS-NDVI 和 SPOT-NDVI）和标准化降水蒸散指数（SPEI）。结果表明：（1）2000 年至 2018 年，研究区干旱强度呈微弱上升趋势，SPEI 在时间尺度上的线性增长率分别为 1、3、6、9 和 12 个月的-0.002、0.0034、0.0198、0.0234 和 0.0249；（2）在大多数地区（97.6%），干旱与植被呈正相关，植被受干旱影响最大的是长期时间尺度（9 和 12 个月）；（3）随着干旱的持续，植被阻力指数下降，干旱结束后逐渐恢复。森林的抗逆性持续时间最长，为 260 天，而草地和耕地的抗逆性持续时间仅为 170 天。本研究增加了对植被抗旱能力的认识，这些发现为支持 MRYRB 的抗旱响应提供了证据。
