ABSTRACT.
With the increasing frequency of extreme climate events, understanding their impacts on plant photosynthesis and the global carbon cycle is crucial. However, the difference in impact between short- and long-term scales remains unclear. This study analyzes gross primary productivity (GPP) responses to 26 extreme climate indices (ECIs) at annual and monthly scales from 2001 to 2020 by using four global GPP products derived from light use efficiency, solar-induced fluorescence, and process-based models. The results from different temporal scales consistently indicate that background hydrothermal conditions can generally modulate GPP responses to extreme climate events. Furthermore, GPP is strongly correlated with ECIs at the monthly scale, particularly with extreme temperature indices, whereas it is predominantly influenced by extreme precipitation indices at the annual scale. This pattern arises because vegetation responds rapidly to temperature fluctuations with strong relationships at short-term scales, while cumulative and lagged influences are observed for precipitation, with great impacts on vegetation over long-term scales. Although structural and input disparities among different GPP products may introduce uncertainties in the conclusions, this study fundamentally reveals the crucial characteristic of temporal scale dependence in GPP responses to extreme climate events.
