| 透明箱法监测稻田生态系统CO2通量的研究 |
| 摘要点击 2372 全文点击 1652 投稿时间：2004-12-25 修订日期：2005-03-11 |
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| 中文关键词 CO2通量 透明箱法 稻田生态系统 |
| 英文关键词 CO2 flux transparent chamber paddy ecosystem |
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| 中文摘要 |
| 采用透明箱法对稻田生态系统CO2通量进行了田间定位观测,并对透明箱内CO2浓度的变化规律及拟合方法进行了探讨.结果表明,在水稻生长旺盛期的晴天(白天),箱内CO2浓度随测定时间呈非线性变化,因此用常规的线性拟合法(LR)计算的CO2净吸收通量明显低于指数一级动力学拟合法(ER).在水稻生长旺盛期的阴天、成熟期以及夜间,箱内CO2浓度随测定时间表现为线性变化,LR法与ER法的CO2净吸收通量计算结果无显著差异.在水稻生长期间,基于LR法的稻田生态系统碳累积吸收量结果明显低于ER法,而后者与常用方法(植物净固定碳量减去土壤异氧呼吸排放碳量)的计算结果比较接近.证实了当植被同化速率较强时,采用ER法对透明箱内CO2浓度随时间的变化进行拟合并计算CO2净吸收通量较为适宜.同时表明采用透明箱法观测农田生态系统CO2通量是可行的. |
| 英文摘要 |
| Closed chamber provide a valuable tool for measuring CO2 exchange fluxes.In general,the change rate of CO2 concentration is assumed to be constant in the short measurement time and a linear regression method is used to estimate the CO2 fluxes.However,due to the physical and physiological effects,the change rate of CO2 is not always constant.A linear regression method and an exponential regression method are compared in this study.Results show that during the growing stages except for the ripening,non-linear relationship of CO2 concentration versus time was estimated in the sunny daytime.Absolute values of CO2 fluxes calculated by linear regression were lower than that by exponential regression.Whereas,CO2 concentration changed linearly with time in cloudy days or in nighttime.And no significant difference was found between the results calculated with these two methods.Accumulative CO2-C fluxes with exponential and linear regressions were compared with the values of net ecosystem exchange of CO2-C(NEE), which were calculated by net primary production(NPP) minus soil respiration.The values with the exponential regression method were closer to NEE than those with linear regression.Therefore,the linear regression method could result in underestimation of carbon budget of ecosystem.Based on transparent chamber measurement,the exponential regression is more feasible to calculate CO2 fluxes than the linear regression. |
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