Abstract: Extreme climate events can substantially affect gross primary productivity (GPP) and the stability of carbon sinks of wetlands by altering hydrothermal conditions. However, national-scale evidence on how wetland GPP responds to different types of extreme climate events across China remains insufficient to support adaptive wetland ecosystem management. We focused on wetland vegetation across China and combined sensitivity analysis with partial correlation analysis to quantify the response intensity and dominant controls of wetland GPP to extreme climate events during 2001-2023, and further analyzed the lag characteristics of wetland GPP responses. The distributed lag models were applied to assess the duration and direction of the persistent effects of extreme climate events. The results showed that extreme climate events showed pronounced regional heterogeneity during 2001-2023, with precipitation-related extreme events exhibiting stronger spatial variability than temperature-related extreme events. Nationally, 98.7% of wetland pixel GPP showed an increasing trend (Sen slope β_sen ranging from 2.112 to 18.640 g C·m^-2·a^-2). Among them, the proportion of pixels with significant GPP changes in the northern temperate wetlands accounted for the highest percentage (48.3%) of the wetland area in this subregion. Warm days (TX90p) and consecutive wet days (CWD) significantly increased the GPP detrended anomaly by 18.26 g C·m^-2·a^-1 and decreased by 34.99 g C·m^-2·a^-1, respectively. TX90p was the dominant climatic control over wetland GPP variability (partial correlation coefficient ranging from 0.180 to 0.488). Wetlands in temperate zones and the plateau region were most sensitive to extreme heat events (with sensitivity coefficient β of TX90p ranging from 0.376 to 0.648). By contrast, subtropical and tropical wetlands were more strongly controlled by precipitation-related extremes (with β of the maximum 5-day precipitation amount ranging from -0.516 to -0.366). Wetland GPP responded synchronously to extreme climate events, exhibiting significant negative memory effects for extreme heat and drought events, a significant positive memory effect for extreme precipitation events, and a negative but non-significant memory effect for extreme cold events. These findings advanced our understanding of wetland GPP responses to extreme climate events and would provide scientific support for assessing wetland carbon-sink stability and informing wetland conservation under increasing climate-extreme risks.

Key words: wetland, gross primary productivity, extreme climate event, sensitivity analysis, memory effect