Potential of the Silpho Moor experimental birch plots as a habitat for Lumbricus terrestris

It is argued that the podzol of Silpho Moor could be converted under birch to a typical brown earth only if it could sustain an earthworm population with a Lumbricus terrestris biomass of not less than 100 g m^?2. No worms of this species were found under experimental birch plots 30 yr old. The presence of podzolizing species in the ground vegetation; the low pH of the raw humus layer; the low Ca and N supply in the soil, litter and rainfall; and the impeded soil drainage lead to the conclusion that colonization by L. terrestris is unlikely.