Naturally, large parts of the Swiss Plateau are characterised by wetlands and meandering rivers. That this is no longer the case today is the result of centuries of efforts to obtain dry land. But how did this process take place? What were the relevant actors and what were their motivations? And what can be said about the ecological consequences of this development?
In this volume we present the results of a research project on the history of wetlands in Switzerland since 1700, which comprises (a) a historical analysis of the development of land use in wetlands and the actors involved, (b) a historical-cartographic reconstruction of wetland extent since 1850 and (c) an evaluation of ecological effects of changes in wetlands on various organisms groups.
In the historical analysis we focus on the different actors and try to reconstruct their goals and practices as impartially as possible and to place them in their contemporary context. With this approach, the present study differs from previous publications of the historical development of wetlands in Switzerland, which often describe it unilaterally either as a history of progress or as a history of loss, depending on the economic and ecological value system of the authors.
The area reconstruction is based on digitized and homogenized signatures from national map series, as they have been available since about 1850. Since 1850, the wetlands have been reduced by more than 90 percent due to peat extraction and drainage, which means that these habitats have largely disappeared from the landscapes of the Swiss Plateau, with a corresponding impact on carbon stocks: since 1850, around 85 percent of the originally existing carbon has disappeared in organic soils and contributed to the increase in CO₂ in the atmosphere. The decline in wetlands has had an impact on the populations and species numbers of animal and plant species that depend on these habitats. Bog plant species adapted to extreme site conditions have experienced an above-average decline, as have bird species from reed areas and invertebrates if they are dependent on moist or wet sites during their life cycle. The fact that the development is not irreversible is shown by amphibians or dragonfly species that can react positively to well-done conservation projects.