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

Fluxes of CO(2), CH(4), and N(2)O 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 CH(4), N(2)O, and soil moisture. Except for N(2)O, large seasonal variations were observed with generally higher gas fluxes during the summer. CO(2) and CH(4) fluxes were significantly dependent on changes in ambient temperature, whereas N(2)O fluxes were more affected by soil moisture. A good correlation between CO(2) production and CH(4) uptake was observed, but no relationship was found between N(2)O emissions and either CO(2) or CH(4) fluxes. Depth profiles of the CH(4) mixing ratio in soil air consistently showed an exponential decrease with depth, whereas N(2)O 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.