Abstract: The height growth of Phragmites communis population conforms to the Jaw of reciprocal equation, which reduces gradually during growing seasons. The dynamics of population height growth is significantly positively correlated with effective accumulated temperature of environment and negatively correlated with accumulated precipitation. The variation of net aboveground production conforms to the Logistic model, which is significantly positively correlated with effective accumulated temperature. The dynamics of population height and net aboveground production reflects the integrated interactions between individual development rhythm in population and environmental factors.

Key words: double season paddy field, rice straw return into soil, soil carbon sequestration, methane emission, net carbon sink