Effects of Medicago sativa, Taraxacum officinale and Bromus sterilis on the density and diversity of Collembola in grassy arable fallows of different ages

The density and diversity of Collembola of nine grassy arable fallows of different ages were investigated in a factorial design with the factors ‘plant species’ (legume: Medicago sativa, herb: Taraxacum officinale, grass: Bromus sterilis) and ‘age class’ (2–3, 6–8 and 12–15 years) including the random effect ‘site’ (1–9). In May 2008, four plots were selected randomly at each fallow. Within each plot five M. sativa, T. officinale and B. sterilis plants were extracted with their associated soil using steel cylinders. The material from each plant species was used for extraction of Collembola and for determination of environmental parameters. Thus, the new aspect of the present study compared to other field studies investigating the relationships between plant and Collembolan communities is the focus on the “micro-scale”, investigating the Collembolan communities of the soil associated with single plants.We found that species richness and density of total and euedaphic Collembola were significantly higher in B. sterilis than in T. officinale samples with the M. sativa samples being intermediate. Fine-root feeding euedaphic Collembola particularly benefited from the higher amount of fine roots in B. sterilis samples. We also discovered that the age of the fallows had no significant influence on the number of Collembolan species and the density of the Collembolan groups. Notably, however, species of the epedaphic genera Lepidocyrtus and Sminthurinus were associated with the 12–15 year-old fallows and presumably benefited from the high number of plant species in the old fallows. Finally, canonical correspondence analysis (CCA) indicated that the soil organic matter content and the microbial biomass, both potential food sources for many Collembolan species, were important structuring forces for the Collembolan communities.