The effect of topsoil removal in restored heathland on soil fauna, topsoil microstructure, and cellulose decomposition: implications for ecosystem restoration

Communities of soil macrofauna, oribatid mites, and nematodes as well as vegetation and soil chemistry were studied on twelve plots representing three replicates of the following treatments: agricultural meadow, heathland, and heathland restored either by partial or complete topsoil removal 15 years earlier. We also studied the effect of soil macrofauna on decomposition and the microstructure of the soil surface layer with litterbags in combination with the analysis of thin soil sections. The communities of soil macrofauna and oribatid mites significantly differed between agricultural meadows and heathlands. The partial and complete topsoil removal plots were more similar to heathlands with respect to macrofauna and to agricultural meadows with respect to oribatid mites. The density and diversity of soil macrofauna was higher in agricultural meadows than in heathlands; in particular, earthworms, litter transformers, root feeders, and microsaprophags were more abundant on meadows. Heathlands, in contrast, contained a much higher diversity of oribatid mites. The community structure of nematodes did not significantly differ among the treatments. Analysis of thin soil sections revealed a thick organic fermentation layer in heathlands, which was absent in agricultural meadows and only weakly developed in the topsoil removal plots. In agricultural meadows, litterbags and thin soil sections indicated that abundant macrofauna, including endogeic earthworms, were very effective in removing the litter from the soil surface and mixing it into the mineral soil. Possible effects of this soil mixing on restoration success are discussed.