Interactions of earthworms (Octolasion lacteum), millipedes (Glomeris marginata) and plants (Hordelymus europaeus) in a beechwood on a basalt hill: implications for litter decomposition and soil formation

Effects of endogeic earthworms (Octolasion lacteum) and millipedes (Glomeris marginata) on litter decomposition and soil formation were investigated in field microcosms with and without plants (Hordelymus europaeus). Microcosms in a beechwood on a basalt hill in northern Hesse (Germany) were exposed for 21 weeks during the vegetation period. Previous studies had shown that anecic earthworm species were almost absent and that the density of epigeic species was low at that site. The presence of H, europaeus strongly affected Litter consumption and body mass of millipedes and earthworms. Litter consumption by G. marginata was 65+/-17 mg dry wt g(-1) fresh wt day(-1) in treatments without plants and only 38+/-30 mg dry wt g(-1) fresh wt day(-1) in treatments with plants. Litter consumption strongly depended on millipede size, specific litter consumption being considerably greater for small individuals than for larger. O. lacteum did not feed on intact beech leaf litter, but removed the faecal material of G. marginata. As a consequence,the biomass of earthworms increased in treatments with G. marginata, whereas their biomass decreased in treatments without millipedes. Presumably, faecal material of millipedes is an important food resource for these endogeic earthworms. It is concluded that the combined action of millipedes and endogeic earthworms is essential for the formation and maintenance of the mull soil of the beechwood studied. (C) 1998 Published by Elsevier Science B.V.