• 论文 •

### 温带森林土壤排放CO2、CH4、N2O时空特征

1. 中国科学院国家计划委员会地理研究所,北京100101
• 收稿日期:1995-05-01 修回日期:1996-11-01 出版日期:1996-12-15 发布日期:1996-12-15

### SEASONAL VARIATIONS OF CO2, CH4 AND N2O FLUXES FROM TEMPERATE FOREST SOIL

Dong Yunshe, Peng Gongbing, Li Jun

1. Institute of Geography. Chinese Academy of Sciences, Beijing 100101
• Received:1995-05-01 Revised:1996-11-01 Online:1996-12-15 Published:1996-12-15

Abstract: Using the enclosed chamber technique, CO2, CH4 and N2O soil fluxes were measured during one year in a forest near Darmstadt, Germany. Fluxes measurements were made before (undisturbed forest soil) and after the removing of soil litter (leaves and humus layer) form the forest floor (disturbed soil). Gas fluxes from the removed leaves and humus were also measured. CH4 and N2O soil air concentration and soil moisture profile were measured during the period July to December.The average Fluxes from undisturbed forest soils are: 2800gCO2/(m2.a),-0.64gCH4/(m2.a), and 0.05gN2O/(m2a). With the exception of N2O signific4nt seasonal variation were observed, with the higher fluxes during thesummer. In general, the fluxes obtained in Darmstadt are in agreement with values reported for similar temperateforests. CO2 and CH4 fluxes show a significant dependence to changes in ambient temperature, whereas N2Onuxes increase with soil moisture ranging between 7% and 20%, with an abrupt decrease at 22%. A goodcorrelation between CO2 production and CH4 consumption was observed, suggesting that methane uptake by soilsis related with the soil respiration process. No relationship was found between N2O emissions rates and CO2 orCH4 fluxes.Very similar profiles of CH4 in soil air (exponential concentration decrease with depth) were observed in allmeasurements, whereas N2O profiles were highly related to the changes in soil moisture, e.g. higher concentrationof N2O were found at the 20 to 50cm layer, during periods when the layer 0 to 15cm had relatively high soilmoistures.when the leaves and the layer of humus were removed from the forest floor, significant changes in thefluxes were observed, indicating that the litter layer plays an important role in the soil-atmosphere interaction. Inthe disturbed soil, CO2 and N2O emissions decrease in average by 23% and 50%, respectively, and CH4consumption increase by 17%. The decrease of CO2 emission is likely related to the activity of the removed humuslayer, that emits CO2, however, the reduction in N2O emission should to be mainly related to changes in theconditions (e.g. increase of oxygen concentration) in the active soil layer. Leaves and humus neither emit norconsume significant amounts of CH4 and the increase of CH4 consumption in the disturbed soil should be mainlydue to an increase of the transport of atmospheric CH4 (and O2) to the region where methane is consumed. Adecrease of the humus layer during last decades, due to effects of air pollution, has likely produced an increase ofthe consumption of atmospheric CH4 by forest soils.

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