Preventing acidification and eutrophication in rich fens: Water level management as a solution?

For this thesis, I examined the effects of the re-introduction of fluctuating surface water levels in freshwater wetlands. These systems, and especially the rich fen wetlands that I focused on, often consist of a mosaic of aquatic, semi-aquatic and terrestrial vegetation types, including many biodiverse communities with high numbers of endangered species. Rich fens are protected under the European Habitat Directive (transition mires and quaking bogs, type H7140), and are characteristic for well-buffered (with respect to acidity) and nutrient-poor conditions. Next to overall eutrophication, high NH4-concentrations may specifically be toxic to bryophytes and vascular plants in rich fens. For the preservation and restoration of rich fens, it is therefore important to prevent acidification, eutrophication and toxicity.
As a general conclusion, I have been able to unravel the differential effects of water table fluctuation in rich fens in relation to surface water quality, peat quality and season, by the combination of correlative field research, large-scale and smaller scale field manipulation experiments, climate room and peat incubation experiments. In this way, this thesis not only contributes to more fundamental biogeochemical and ecological issues related to surface water level fluctuations, but can also be used for decision support in the hydrological management of rich fens.