关键词: 稻田, CH₄和N₂O排放, 养萍, 施肥, 景观空间格局, 景观指数, 太湖流域, CLUE-S模型, 动态转移

Abstract: CH₄ and N₂O emission from a rice field in northeast China are monitored simultaneously and systematically by using chamber technique to estimate their fluxes from rice fields and to understand the relationship between these two gases emissions.The results show that CH₄ emission from rice field in northeast China is much lower than that in south China, with a daily average emission of 0.079·m^-2 and total seasonal emission of 7.4g·m^-2.Rice fields almost do not emit or deposit N₂O during flooding period, but substantially emit it (average flux 59 μgN₂O.m^-2·h^-1) during non-flooding period.CH₄ and N₂O emissions are greatly enhanced by Azolla and fertilization.Atrade-off between CH₄ and N₂O emissions is observed, which should be considered when mitigation options for reducing greenhouse gas emission are proposed.

Key words: Rice field CH₄ and N₂O emission, Azolla, Fertilization, dynamic transfer, CLUE-S model, Taihu Lake basin, landscape spatial pattern, landscape index