LITTER MICROFLORA SOIL MACROFAUNA INTERACTIONS IN LIGNIN DECOMPOSITION - A LABORATORY EXPERIMENT WITH C-14-LABELED LIGNIN

The decomposition of uniformly C-14-labelled [lignin] lignocellulose mixed with brown rotted or white rotted beech (Fagus sylvatica L.) leaf litter was investigated in laboratory systems at 15-degrees-C for 192 days. In addition, the modification of lignin decomposition by two earthworm species [Octolasion lacteum (Orley) and Lumbricus castaneus (Savigny)] and the diplopod Glomeris marginata (Villers) was studied. (CO2)-C-14 release, total CO2 production, mineral N (N(min)) leaching and pH of the leachate were monitored regularly. (CO2)-C-14-C release from lignin mixed in brown rotted beech leaf litter exceeded that of lignin mixed in white rotted beech leaf litter throughout the experiment. Low mineralization of lignin in chambers containing white rotted beach leaf litter was accompanied by enhanced CO2 production and N(min) leaching, which indicates inhibition of lignin decomposition due to excessive nutrient supply. Earthworm activity resulted in an increase in cumulative N mineralization and (CO2)-C-14-C release from lignin, but did not affect total CO2 production by the systems during the experiment. The presence of G. marginata enhanced cumulative N(min) leaching and total CO2 production by the systems but did not affect overall (CO2)-C-14-C release from lignin. Except for the increase in (CO2)-C-14-C release from lignin due to earthworm activity, animal effects were independent of white or brown rotted beech leaf litter.