稻田生态系统CO2通量的日变化特征

研究稻田生态系统与大气间CO2交换通量的变化特征及规律可以为准确估算和评价稻田生态系统碳源/汇强度提供科学依据。采用涡度相关技术对中国亚热带稻田生态系统CO2交换通量进行了连续监测,并对CO2通量的日变化规律进行了分析。结果表明,稻田生态系统CO2通量具有明显的日变化特征。白天以吸收CO2为主,夜间表现为排放CO2;CO2通量的日变化模式有单峰型、双峰型和不规则型。稻田CO2通量日变化强度受水稻生长状况影响,水稻生长旺盛期白天CO2吸收通量、夜间排放通量以及日净吸收CO2通量均高于生长前期和成熟期;且早稻与晚稻间有明显差别。

Diurnal Characteristics of CO2 Fluxes in Rice Paddy Ecosystem in China

Measurements of the net exchange of CO_2 between paddy ecosystem and the atmosphere benefit to determinate the annual carbon source or sink strength of the paddy ecosystem.In the research,CO_2 fluxes in rice paddy ecosystem in subtropical hilly region were measured continuously using eddy covariance technique.The objectives were to investigate the variation of CO_2 fluxes in the paddy ecosystem on daily temporal scale.Results showed a distinct diurnal pattern of CO_2 fluxes was observed,with uptaking CO_2 from the atmosphere during the daytime and emitting CO_2 to the atmosphere in the nighttime.It took on single-peak type,double-peak type and irregular-peak type dominated by radiation.The strength of CO_2 fluxes daily change responded differently in different growing stages of rice.In the blooming stage,these rates of absorption in daytime,emission in night and daily averaged were higher than those in tillering and ripening stages,respectively.And there was difference between early and late rice.