土壤呼吸、农田CO_2排放及NEE的比较研究

The comparative study of the soil respiration,CO_2 emission and NEE from the farmland in the north of China

在农田温室效应研究中存在着对土壤呼吸、农田CO2排放及NEE界定不明确、混淆概念的现象。利用箱法在一年两熟及一年一熟区对三者进行了原位测定,结果表明,一年两熟区冬小麦(Triticum aestivum L.)拔节孕穗期土壤呼吸占农田CO2排放的20%左右,作物呼吸排放在此期是主要的CO2排放源,由于光合作用固定CO2速率高于呼吸作用排放CO2的速率,NEE平均值为-319.88mg·m-2·h-1,农田表现为大气CO2的汇;在一年一熟的农牧交错区,土壤呼吸、农田CO2排放通量均明显低于一年两熟农田,NEE平均值为142mg·m-2·h-1,表现为大气CO2的源。本研究通过对土壤呼吸、农田CO2排放及NEE的比较,指出通过技术方法的改进,NEE是今后的研究方向。

The study of greenhouse effect has received wide attention, however, there are still confusion and misunderstanding in the concepts of soil respiration, CO2 emission and NEE in farmland greenhouse effect research. This study used static chamber method in double cropping and one crop per-year areas. The results show that soil respiration accounted for 20% of the total CO2 emission at the jointing stage and booting stage of winter wheat（ Triticum aestivum L. ）, while crop respiration was the main CO2 emission source Because the photosynthetic fixation rate of CO2 was higher than its emission rate, the mean value of NEE was about -319.88 mg.m2.h% so the farmland was the CO2 sink of the atmosphere. Whereas, in the agro-pastoral regions, both the soil respiration and the CO2 emission flux from farmland were obviously lower than the double cropping area, with the mean value of NEE being about 142 mg·m^-2·h^-1, acting as CO2 source. Through comparison of soil respiration, CO2 emission and NEE, this paper points out that the main research direction of greenhouse gas emission is NEE in the future.