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 (Gl omeris marginata) on litter decomposition and soil formation were inve stigated in field microcosms with and without plants (Hordelymus europ aeus). Microcosms in a beechwood on a basalt hill in northern Hesse (G ermany) were exposed for 21 weeks during the vegetation period. Previo us studies had shown that anecic earthworm species were almost absent and that the density of epigeic species was low at that site. The pres ence of H, europaeus strongly affected Litter consumption and body mas s 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, specif ic 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, wher eas their biomass decreased in treatments without millipedes. Presumab ly, faecal material of millipedes is an important food resource for th ese endogeic earthworms. It is concluded that the combined action of m illipedes and endogeic earthworms is essential for the formation and m aintenance of the mull soil of the beechwood studied. (C) 1998 Publish ed by Elsevier Science B.V.