From species composition, it appeared that the majority of earthworms occurring in the mineral soil deeper than 10 cm and 20 cm in the ridge and bottom plots, respectively did not feed on surface litter. Based on this finding, biomass of "potential" litter-feeding earthworms was estimated and was found to differ only marginally between the two plots on the studied slope. Judging from the carbon content of earthworm faeces, earthworms in the A
0-layer were considered to feed exclusively on A
0-layer material. Biomass of these "actual" litter-feeding earthworms was greater in the ridge plot than in the bottem plot. Even when the biomasses of earthworms in the topsoil (0-10cm) and "actual" litterfeeding earthworms were summed, it was still somewhat larger in the ridge plot than in the bottom plot. The "mull-type" humus in the bottom plot and the "mor-type" hunus in the ridge plot indicated the relatively faster consumption of surface litter by soil organisms in the bottom plot. The estimated biomasses of both "potential" and "actual" litter-feeding earthworms were negative to a great contribution of earthworms to this differential consumption of surface litter and thus to the differential development of the A
0-layer observed between the two plots.
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