Fluxes of CO2, CH4 and N2O from a temperate forest soil: the effects of leaves and humus layers

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ABSTRACT

Fluxes of CO2, CH4, and N2O from forest soils were measured with an enclosed chamber technique between October 1990 and December 1991 in a deciduous forest near Darmstadt, Germany. Flux measurements were made before and after the removal of leaves and humus layer from the forest floor, and gas fluxes from the leaves and humus alone were also measured as well as depth profiles of CH4, N2O, and soil moisture. Except for N2O, large seasonal variations were observed with generally higher gas fluxes during the summer. CO2 and CH4 fluxes were significantly dependent on changes in ambient temperature, whereas N2O fluxes were more affected by soil moisture. A good correlation between CO2 production and CH4 uptake was observed, but no relationship was found between N2O emissions and either CO2 or CH4 fluxes. Depth profiles of the CH4 mixing ratio in soil air consistently showed an exponential decrease with depth, whereas N2O profiles were highly variable and appeared to be related to changes in soil moisture. The manipulated soil experiments indicate that the leaves and the humus layers contribute significantly to the soil-atmosphere exchange of trace gases.

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