Joint effects of hydrothermal conditions and phenological events on autumn vegetation senescence across the Mongolian plateau

On the Mongolian Plateau, the autumn phenology of vegetation plays a key role in ecosystem functioning and biodiversity conservation in drylands. Understanding its multifaceted driving mechanisms is essential for predicting ecosystem resilience under global change. This study innovatively couples hydrothermal dynamics with key phenological phases, systematically revealing the multi-factor driving mechanisms of vegetation end of the growing season (EOS) from 1982 to 2022, filling a critical gap in long-term research on senescence period responses. The results indicate that the driving mechanisms for EOS changes are drought-induced advancement and temperature-induced retardation. In most areas, the impact of temperature on the vegetation growth rate (EOS) is more significant than that of drought conditions. At the same time, EOS showed a positive correlation with the peak of the growing season (POS) and a negative correlation with the start of the growing season (SOS). Compared to temperature and drought conditions, the key phenological period has a stronger effect on EOS. Furthermore, structural equation modeling and preseason factor analysis suggest a coordinated process-based mechanism underlying EOS variability. Specifically, climate factors jointly regulate SOS, which then propagates through a “SOS, POS, EOS”cascade to determine the final timing of senescence. In this process, POS is identified as the direct determinant of EOS, while the senescence duration (SD) emerges as a key modulator under drought conditions. This study clarifies and identifies the mechanisms through which these factors drive changes in EOS, and enhance our understanding of vegetation management and climate adaptation strategies in the region. • EOS on the Mongolian Plateau showed a delayed trend, and response to temperature exceeded that to drought. • Climatic influence on EOS are weaker than phenology effects; EOS is controlled by the SOS→POS→EOS progression. • EOS on the Mongolian Plateau reflects natural senescence rather than freezing-induced mortality.