Divergent drought-induced suppression on vegetation and associated feedbacks: Satellite-based observations in 2022 across the Yangtze River basin, China

Abstract

During the summer of 2022, a record-breaking drought event coupled with unprecedentedly low rainfall struck in the Yangtze River basin (YRB) of China. However, the quantitative assessment of the consequences of such extreme drought event remains a significant challenge, which hinders the development of effective mitigation strategies and the enhancement of ecosystem resilience. This study synthesized three satellite remote sensing-based vegetation indices to evaluate the potential effects of such extreme drought, including the solar-induced chlorophyll fluorescence (GOSIF), normalized difference vegetation index (NDVI) and near-infrared reflectance of vegetation (NIRV). Furthermore, a novel ’resistance–resilience’ framework was proposed to explore the mechanisms underlying vegetation responses to extreme drought. The results revealed that regions surrounding the Sichuan Basin, Guizhou Plateau, and Jiangnan Hills were the most severely affected area. Moreover, the summer drought of 2022 led to a marked reduction in vegetation growth across most vegetated areas, as evidenced by negative detrended anomalies in GOSIF (73.7 %), NDVI (90.9 %) and NIRV (80.9 %). Among different vegetation types, evergreen broadleaf forests suffered the most significant reduction, whereas a slight increase happened in grasslands. Furthermore, an inverse relationship was revealed between vegetation resistance and resilience, characterized by weak resistance-strong resilience or strong resistance-weak resilience. Specifically, grasslands in high altitudes exhibited higher resistance with lower resilience, while forests in the Sichuan Basin and Jiangnan Hills generally showed lower resistance with higher resilience. Evergreen broadleaf forests, in particular, are expected to face heightened vulnerability owing to the impact of future droughts. All analyses provide a critical framework for evaluating the potential effects of drought extremes on plant structures and functions, and offers valuable insights for land managers to support sustainable management practices.