Fluxes of CO₂, CH₄ and N2_O from a temperate forest soil: the effects of leaves and humus layers

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.