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研究报告

Characteristic analysis of CO₂ fluxes from a rice paddy ecosystem in a subtropical region

摘要：为评价稻田生态系统大气CO₂的收支状况,2008～2009年江西省农业气象试验站利用涡度相关技术对稻田生态系统的CO₂通量进行了为期一年的连续观测.对观测的数据进行处理和分析表明:在生长季,稻田生态系统CO₂通量总体表现为负值,为CO₂的汇.稻田生态系统CO₂通量具有明显的日变化特征,白天净吸收CO₂的量大于夜间呼吸释放CO₂的量.水稻拔节到乳熟阶段吸收CO₂的效率以及分蘖至抽穗期CO₂的净固定量均明显高于生长初期和生长后期.在非生长季的10月中旬晚稻收获后至次年4月,除了3月稻田生态系统略向大气吸收CO₂外,其余各月份均向大气释放CO₂,非生长季稻田生态系统为大气CO₂的源.在一个年周期内,进一步累加生长季稻田净吸收和非生长季净释放的CO₂量可知,试验区稻田生态系统从大气中净吸收CO₂的量为14.35t·hm^-2,其中早稻吸收CO₂为8.81t·hm^-2,晚稻吸收CO₂为11.71t·hm^-2,非生长季向大气释放CO₂为6.17t·hm^-2,稻田生态系统总体表现为CO₂的汇.

Abstract：In order to evaluate carbon source or sink strength,CO₂ fluxes from a paddy ecosystem were continuously measured using the eddy covariance technique over the course of a year. During a cropping paddy season,the summation of CO₂ fluxes from paddy ecosystem was negative and the paddy ecosystem was a carbon dioxide sink. Distinct CO₂ fluxes characteristic of diurnal variation were observed. The net absorptive capacity of CO₂ in the day was much more than CO₂ release in the night. The absorbed efficiency of CO₂ from rice elongating stage to milk stage was higher than other stages. The net carbon dioxide fixation from tillering stage to flowering stage was much more than other stages. During a non-cropping paddy season,i.e.,from late October(after the rice harvest) to the following year in April,the paddy ecosystem absorbed a small quantity of CO₂ only in March,while in other months it released CO₂,becoming a carbon source. The paddy ecosystem absorbed 14.35 t·hm^-2of CO₂ from the atmosphere over a year,including 8.81t·hm^-2 of CO₂ absorbed by early season rice and11.71 t·hm^-2 by late season rice. Although the paddy ecosystem released 6.17 t·hm^-2 of CO₂ during a non-cropping paddy season,it was an overall carbon dioxide sink for the atmosphere.