Restoration of fens and peat lakes: a biogeochemical approach

Worldwide, fens and peat lakes are being threatened by multiple environmental problems, such as desiccation, eutrophication, pollution and global warming. This has led to increased peat decomposition and sludge production, disappearance of macrophyte species, biodiversity losses and hampered terrestrialization. This thesis emphasizes the essential role of biogeochemical knowledge in the ecological restoration of fens and peat lakes: the regulation of mobilization, reduction, sulphide toxicity and peat decomposition all have important implications for water and sediment quality, and for vegetation development. As indicators of both biogeochemical processes and potential biodiversity, sediment and sediment pore water ratios provide valuable diagnostic and prognostic tools for the restoration of fens and peat lakes. These ratios are not only useful for risk assessment, but also for selecting the most promising measures. In many cases, however, it turns out to be difficult to tackle the high P concentrations present by P immobilization methods or dredging. Besides decreasing the influx of nutrient-rich water, it is therefore important to prevent the influx of alkaline and S-rich water, because this hydrological measure will slow down decomposition processes and internal mobilization of nutrients. It can be concluded that if the right measures are chosen on the basis of simple measurements, it is certainly possible to restore the biodiversity in declined fens and peat lakes.