基于静态明、暗箱观测估算稻田生态系统—大气CO₂净交换

【作者】 刘春岩；

【导师】 陈万隆； 郑循华；

【作者基本信息】 南京气象学院 ， 大气物理学与大气环境， 2004， 硕士

【摘要】 本研究以太湖地区典型稻麦轮作农田生态系统的水稻生长季为对象，基于静态透明箱、暗箱法观测初步建立了一个估算稻田生态系统-大气CO₂净交换（NEE）的经验模型，并用该模型估算了江苏无锡常规耕作稻田水稻生长季逐时的CO₂净交换通量。 根据该经验模型的估算结果，2003年无锡稻田NEE的季节变化趋势为：返青期至分蘖前期的稻田生态系统表现为弱的CO₂净排放，分蘖后期、拔节期和抽穗期表现为CO₂净固定，日平均净固定通量随生长季逐渐增加，拔节期出现CO₂净固定通量的最大值，抽穗后CO₂净固定通量逐渐下降，进入灌浆、成熟期又表现为CO₂净排放。2003年无锡稻田水稻返青、分蘖、拔节、抽穗、开花和成熟期的日平均NEE分别为0.4～0.5、-2.8～-3.2、-12.0～-13.7、-7.8～-8.9、2.7～3.1和1.0～1.1 g CO₂·m^-2·d^-1，无锡稻田水稻生长季累计NEE为-1424～-1632 kg C·ha^-1。 经验模型估算的R和NEE值同分别采用静态暗箱和透明箱法田间实际观测的R和NEE值非常接近，估算的稻田CO₂净交换日变化和季节变化同其他研究者分别采用涡动相关法和松弛涡动累积法观测到的稻田CO₂净交换日变化和季节变化趋势具有一致性。同田间实测值及其它研究结果的一致性说明经验模型的模拟结果可靠，所建立的经验模型能够比较准确地描述稻田R和NEE的实际变化趋势。更多还原

【Abstract】 The authors take the rice season of Rice-wheat rotation system near Tai Lake as the object and establish an empirical model for determining net CO2 emission from a paddy rice ecosystem using techniques of static transparent and opaque chambers. Then the model is applied to estimate the hourly net ecosystem exchange (NEE) of a normal rice paddy field at a suburb of Wuxi, Jiangsu province during the entire rice season.The modeling results show the seasonal variation of NEE from the paddy rice ecosystem in Wuxi in the rice season of 2003. Fractional net CO2 emission occurred during the riving and the early tillering stage. Net CO2 fixation occurred in the later tillering, panicle initiating and heading stage and daily mean net flux of CO2 fixation appeared with an increasing trend as rice growing. The maximum of net flux of CO2 fixation occurred in the panicle initiating stage. A decline trend in the net flux of CO2 fixation was documented after the heading stage and therefore net CO2 emission occurred in the maturing stage. The daily mean NEE of the investigated rice paddy field are on average 0.4-0.5, -2.8-3.2, -12.0-13.7, -7.8-8.9, 2.7-3.1, and 1.0 -1.1 g CO2 m2 d-1 in the riving, tillering, panicle initiating, heading, flowering and maturing stage, respective, hi the rice season of 2003, with an seasonally accumulative NEE of-1424-1632 kg Cha-1.The R and NEE estimated using the empirical model fit the R and NEE observed in the field using techniques of static transparent and opaque chambers leasonably well. The diurnal and seasonal variations of NEE estimated using the empirical model are consistent with those observed by other researchers using the methods of eddy covariance and relax eddy accumulation. These suggest that the NEE estimated using the empirical model established in this study is reliable and the empirical model can accurately determinate the actual variations of R and NEE in the field.更多还原