Abstract Ongoing climate change is expected to increase the frequency and intensity of extreme hydrological events globally. Since the carbon sink function of wetlands is largely driven by hydrology, it is essential to comprehensively understand how these extreme events impact wetland carbon processes. However, the response of the wetland carbon cycle to extreme hydrological events under a changing climate remains uncertain. In this study, we employed the eddy covariance technique to evaluate the impact of extreme hydrological events on the carbon sink strength in an estuarine wetland in the Yellow River Delta. We selected 2 years, 2019 and 2020, with comparable annual rainfall totals but notable differences in seasonal precipitation patterns: the year 2019 was characterized by an extremely dry spring and an extreme precipitation event in summer. The results revealed a 60% decline in annual CO 2 uptake, with net ecosystem CO 2 exchange (NEE) recorded at −105 g C m −2 yr −1 in 2019, compared to −261 g C m −2 yr −1 in 2020. Both the extreme drought in spring and the extreme precipitation in summer reduced the maximum rates of photosynthesis throughout the growing season. Finally, a comparison with historical monitoring data from 2011 to 2020 at the study site revealed that the annual CO 2 sink magnitude in 2019 decreased by 54% compared to the multi‐year average NEE of −228 ± 58 g C m −2 yr −1 . This study provides a novel perspective on how extreme hydrological events influence the carbon budget of wetlands.
WEI et al. (Sun,) studied this question.