Seasonal not annual precipitation drives 8-year variability of interannual net CO2 exchange in a salt marsh

Salt marshes are significant contributors to global “blue carbon” resources, and these habitats sensitive precipitation events due periodically dry-wet alternation induced by tides. However, whether annual marsh-atmospheric CO2 flux responds more or seasonal remains unclear. Here, eight years (2012-2019) of eddy covariance data were evaluated determine typical budgets, we assessed the effect on interannual net ecosystem exchange (NEE) in a salt marsh Yellow River Delta, China. The was sink for atmospheric each study years, with an 8-year average NEE -51.7 ± 9.7 g C m?2 a?1 varying from -8 -85 a?1. Annual mainly regulated levels during early growth stage plants, which modulated maximal plant biomass accumulation via water-salt transport. Besides, spring distribution experiment showed that wetter plants enhanced carbon assimilation capacity decreasing soil salinity promoting accumulation. These findings suggest conditions onset growing season crucial variations marshes.