为了搞清我国农业生态系统碳循环状况,以１９９０年和２０００年为例,对系统周年内碳的吸收、排放、固定和转移量进行了计算分析,绘制出全国农业生态系统碳循环框图。结果表明,１９９０年和２０００年碳的排放、固定、转移量占当年吸收量分别为８９．７％和９１．０％、９．１２％和７．８３％及１．１８％和１．１６％。说明无论是现阶段还是气候变化后,我国农业生态系统对碳的吸收量均大于排放量,对大气ＣＯ２浓度而言,不是源而是汇。

In order to have a clear idea about the carbon cycle in the agro-ecological system of China,the uptake, emission,fixation and transfer of CO2 by the system in the years 1990 and 2000 are calculated and analysed,and a schematic map of carbon cycle in the agro-ecological system of China is drawn. The results indicate that the percentages occupied by the emission amount,fixation amount and transfer amount are 89. 7% 91.0% and 9.12% of the uptake amount respectively in the year 1990,and they are 7.83%, 1.18% and 1.16% respectively in the year 2000. It can be seen clearly that the CO2 uptake amount of the agro-ecological system of China is greater than the CO2 emission amount,and the system is a"sink"but not a"source"in respect to the atmospheric CO2 concentration in both the current periat and the peried after climatic change.