Comparison of vegetation responses to diverse water sources in the Yangtze River Basin: Insights from meteorological, hydrological, and agricultural drought

• Positive vegetation–water links coincide with droughts. • The negative impact of the soil moisture surplus on greenery health may be more enduring. • Water scarcity hinders plant growth in lower Yangtze areas. • Runoff is the most significant water source influencing flora growth. Understanding the intricate link between water availability and vegetation growth is crucial for preserving ecosystem vitality and facilitating global carbon cycling. The Yangtze River Basin (YRB) features vast subtropical forests, which are vital for global hydrological, carbon, and energy flows. Investigating the influence of the water supply on vegetation dynamics in this basin is crucial, particularly in light of the challenges posed by climate change. However, the response of vegetation to different water sources remains poorly understood. To address this gap, this study explores the influence of precipitation, surface runoff, and soil water on vegetation growth in the YRB via hydrologic modelling and remote sensing data from 2003 to 2021. The results revealed a decreasing trend in drought-prone areas. The overall vegetation growth has progressively improved despite challenges posed by water scarcity. More areas in the YRB are affected by water shortages than surpluses in terms of vegetation growth. During the growing season, vegetation is primarily affected by water shortage, although in exceptional cases, it is constrained by excess water, which typically occurs during the nongrowing season. In the upper and middle Jinsha River Basin, vegetation growth is primarily restricted by water surpluses, while in the middle and lower YRB, constraints commonly arise from water deficits. Additionally, surface runoff and soil moisture play more significant roles in influencing vegetation growth than precipitation. By revealing the dynamics of the vegetation–water correlation, our research aims to provide valuable insights for managing the dynamic balance between water and vegetation in subtropical regions.