Abstract:  CO2 flux was measured continuously by using the eddy covariance technique at Jinzhou agricultural ecosystem station in 2008, and its dynamic characteristics during the growth season (from May to October) and the non-growth season were investigated. The results show that diurnal dynamic variation of CO₂ flux in the maize ecosystem is not obvious during the non-growth season, while that is significant during the growth season and varies in a “U” shape curve. The maximum value is -1.19 mg·m^-2·s^-1 and appears at 12:00 o’clock. The diurnal trends are also a “U” shape curve in the different phenophases. The maximum range of diurnal variation of CO2 flux is 0.07～-0.23 mg·m^-2·s^-1 in the different development stages. NEE is -652.8 g·m^-2 and 499.8 g·m^-2 during the growth season and the non-growth season in the maize agroecosystem, respectively. Carbon budget is -153.0 g·m^-2 in 2008 and it means that a maize agroecosystem is the carbon sink.

Key words: Maize agroecosystem, Eddy covariance technique, CO₂ flux, Dynamic variation