FLUXES OF CO2, CH4 AND N2O FROM A TEMPERATE FOREST SOIL - THE EFFECTSOF LEAVES AND HUMUS LAYERS

Fluxes of CO2, CH4, and N2O from forest soils were measured with an en closed chamber technique between October 1990 and December 1991 in a d eciduous forest near Darmstadt, Germany. Flux measurements were made b efore and after the removal of leaves and humus layer from the forest floor, and gas fluxes from the leaves and humus alone were also measur ed as well as depth profiles of CH4, N2O, and soil moisture. Except fo r N2O, large seasonal variations were observed with generally higher g as fluxes during the summer. CO2 and CH4 fluxes were significantly dep endent 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 mix ing ratio in soil air consistently showed an exponential decrease with depth, whereas N2O profiles were highly variable and appeared to be r elated to changes in soil moisture. The manipulated soil experiments i ndicate that the leaves and the humus layers contribute significantly to the soil-atmosphere exchange of trace gases.