Does the species composition of Collembola affect nitrogen turnover?

We investigated the Collembola in a field (integrated fanning) and a fallow which both had previously been similarly managed (conventional farming, cereals). Population structures and temporal dynamics differed considerably. Defaunated soil from the arable field was reinoculated with single collembolan species (Folsomia quadrioculata group, Isotoma notabilis, Onychiurus armatus group, and Lepidocyrtus cyaneus), or a mixture of these species, in a laboratory experiment. These treatments were compared with the defaunated control, showing species - specific differences in the extent and dynamics of nitrogen leaching. While the single species mainly had an immobilising effect, the species mixture increased nitrogen mineralisation. The significant effects of L. cyaneus and I. notabilis on nitrogen immobilisation would amount to 9 and 7 kg NO3--N per hectare and year, respectively, assuming that the favourable laboratory conditions apply in the field for one third of the year. (C) 1998 Elsevier Science B.V.