Cumulative and Lag Effects of Meteorological Drought on Vegetation Cover in the Yellow River Basin

Abstract

Global warming has led to an increase in the frequency of meteorological drought events, posing a significant threat to ecosystem security, particularly in arid and semi-arid regions. Previous studies have utilized correlation analyses to examine the relationship between vegetation and meteorological drought; however, a knowledge gap remains regarding the causal process between the two. This study investigates the linkage between solar-induced chlorophyll fluorescence (SIF) and the standardized precipitation evapotranspiration index (SPEI) in the Yellow River Basin (YRB) from 2001 to 2019 and explores the cumulative and lagged effects of vegetation SIF in response to SPEI. The results indicated that the cumulative and lag effects of vegetation SIF response to meteorological drought varied with the intensity of water stress. Vegetation in arid regions exhibited poor meteorological drought tolerance and high sensitivity, and the cumulative time and lag time of SIF response to SPEI are 6.5 and 2 months, respectively. Forest, compared with cropland and grassland, demonstrated greater meteorological drought tolerance and reduced sensitivity. For forests, the cumulative and lag time of SIF response to SPEI were 8.7 and 7.4 months, respectively. Grassland was more influenced by precipitation, while forests were more affected by temperature. By analysing the response of SIF to SPEI, this study focuses on the cumulative and lag effects of vegetation on meteorological drought, which will strengthen the understanding of the response of vegetation to meteorological drought in arid and semi-arid areas.