Linking above- and below-ground biodiversity: abundance and trophic complexity in soil as a response to experimental plant communities on abandoned arable land

1. This study investigates the effects of experimental plant communities on different trophic levels in the soil food web of abandoned arable land. 2. In April 1996, a biodiversity experiment commenced using a continuation of agricultural crop rotation (CCR), spontaneous succession with naturally colonizing plant species (NC) and late-successional plant species sown in low-diversity (LD, four plant species) and high-diversity (HD, 15 plant species) communities. The nematode community was used as an indicator of the influence of the experimental plant communities on different trophic levels in the soil food web. 3. The nematode abundance in the experimental plant communities differed from that of the continued crop rotation, but there were hardly any differences between the natural, the low-diversity and the high-diversity plant communities. 4. The abundant plant-feeding nematodes and the somewhat less abundant bacterivorous nematodes were stimulated most by the sowing treatments. Fungivorous nematodes were stimulated less, while the numbers of omnivorous and carnivorous nematodes did not change significantly. 5. The diversity of the nematode community did not change over 2 years. 6. It is concluded that experimental plant communities have either small short-term effects or a delayed impact on the soil food web compared with the effect they have on above-ground invertebrate community development.