The loss of biodiversity is recognized as a worldwide threat, consequently also Switzerland is strongly affected. One of the main reasons for the loss of biodiversity is the destruction, degradation and fragmentation of species-rich habitats due to urban development or agricultural land use. Even though conservation efforts were strengthened some decades ago, biodiversity loss was not halted; a trend-reversal is not in sight. Evidence is growing that it is not sufficient to protect the remnants of species-rich habitats, but that restoration of habitat is necessary to enlarge and re-connect the small-scale remnants to larger networks. Successful restoration seems possible when the existing vegetation including roots and the topsoil are removed. However, topsoil removal methods have provoked a dispute between nature conservation and soil protection agencies due to a potential negative impact of removing the topsoil layers on soil community diversity and soil processes. This dispute is ongoing, mainly due to a lack of field studies and scientific data.
The aim of our study is to fill this gap in knowledge by assessing the effects of topsoil removal on soil diversity and soil processes by using a large-scale restoration experiment established over 20 years ago in Eigental valley (canton of Zürich, city of Kloten). The development of the vegetation was since monitored. We assess how organismic soil functional groups (bacteria, archaea, fungi, nematodes, micro-arthropods, and earthworms) and soil processes (soil respiration, nitrogen mineralization) responded to topsoil removal over long time frames. The findings of the study will immediately fed into practice since official agencies are associated with the project from kick-off.