亚热带稻田生态系统CO2通量的季节变化特征

为估算和评价稻田生态系统碳源/汇强度及其对大气CO₂浓度变化的贡献,研究了稻田生态系统与大气间CO₂交换通量的季节变化特征及其影响因素.采用涡度相关技术对我国亚热带稻田生态系统CO₂交换通量进行了连续监测,在数据剔除、校正和差补的基础上,对瞬时CO₂通量值进行计算求得日CO₂通量值和年CO₂通量值,并对CO₂通量季节变化及其与主要气象因子的关系进行了探讨.结果表明,稻田生态系统光合吸收CO₂通量（GPP）、呼吸排放CO₂通量（R_eco）和净吸收CO₂通量（NEE）的季节变化均呈6～9月较高,1～5月和10～12月较低的对称分布.其中5～9月水稻生长时期的NEE总量占年总量的80%以上,对年NEE总量起决定性作用.光合有效辐射（PAR）和日平均气温（T_a）是GPP与NEE季节变化的最主要影响因子,二者与GPP和NEE分别存在显著的二元线性关系.年净吸收CO₂总量为2?475.6 g/(m²·a),这表明我国亚热带稻田生态系统是大气CO₂的汇.

Seasonal Characteristics of CO2 Fluxes from the Paddy Ecosystem in Subtropical Region

CO2 fluxes from paddy ecosystem in subtropical hilly region were measured continuously using eddy covariance technique. Based on data rejecting, correcting and filling, the daily and annual CO2 fluxes were calculated from the instantaneous values, respectively. The objectives were to investigate the variation of CO2 fluxes on seasonal temporal scale, analyze the relationship between CO2 fluxes and environmental factors, and to quantify the annual net ecosystem exchange (NEE) from the paddy ecosystem. Results show the values of GPP, R(eco) and NEE are higher from Jun. to Sep. and lower in the other months. The NEE from May to Sep. accounted for above 80% of the annual value and is crucial to the whole annual value. Photosynthetically active radiation (PAR) and mean daily air temperature (T(a)) were two main influential factors for controlling the seasonal trend of GPP and NEE and could be described by binary linear functions, respectively. The annual NEE in paddy ecosystem was 2 475.6 g/(m2 x a). This is showed that paddy ecosystem was a carbon sink for the atmosphere in subtropical region.