Delayed senescence end prolongs leaf senescence duration in temperate China

Abstract

Vegetation leaf senescence serves as a pivotal biogeochemical process regulating carbon, water, and energy exchanges between terrestrial ecosystems and the atmosphere. Despite considerable research attention on the end of leaf senescence (T_LSD), its onset (T_LSO) and duration (D_LS) remain poorly understood, limiting our ability to predict autumn phenological dynamics. Here, using four phenological extraction methods, we analyzed the trends in T_LSO, T_LSD, and D_LS across temperate China from 2001 to 2023, along with their climatic and physiological drivers. Our results revealed widespread delays in T_LSD (0.32 ± 0.13 days/year) and T_LSO (0.10 ± 0.16 days/year), leading to a prolonged D_LS (0.21 ± 0.17 days/year). Notably, D_LS variations were predominantly controlled by shifts in T_LSD rather than T_LSO, except in water-limited grasslands and cold-adapted deciduous needleleaf forests. Our analysis revealed that T_LSD showed stronger climate sensitivity than T_LSO, with temperature as the dominant control. Most remarkably, we uncovered a persistent, intrinsic relationship wherein T_LSO constrains T_LSD, independent of external climatic influences. These results suggest that existing climate-driven phenology models likely underestimate autumn phenological responses by neglecting these intrinsic plant physiological controls. Our study highlights the necessities to integrate both internal regulatory mechanisms (particularly T_LSO-T_LSD linkages) and external environmental drivers to achieve more accurate predictions of vegetation responses to ongoing climate change.