Increasing temperature and water level drawdown are two important factors of global change. Both factors are of high importance with regard to the carbon and greenhouse gas balance of peatlands. This project is set up to determine how temperature and groundwater level influence these balances. Furthermore, we give special attention to the underlying processes of methane and nitrous oxide emissions and how these are influenced by temperature and groundwater level.
At the University of Antwerp, an experimental platform was established at which nine greenhouses each contain four mesocosms filled with fen peat. In these mesocosms, the groundwater level is regulated. From April till November, the groundwater level is set at 5, 10, 17 or 24 cm below the surface. During the other six months of the year, water levels are raised with 10 cm (except the highest level, which is only raised with 5 cm). In each greenhouse, temperature is regulated. Three greenhouses remain unheated, whereas the others are either heated by 3 °C or by 6 °C. At regular time intervals, we measure CO2, CH4 and N2O emissions with a dynamic closed chamber. Furthermore, we determine all components of the carbon balance (DOC, POC, VOC and DIC), some components of the nitrogen balance (NO3-, NH4+, DON and DIN) and several important parameters such as O2 concentration, temperature and soil water content. In addition, we also determine concentrations of CO2, CH4 and N2O at different depths in the soil in order to obtain more information about underlying processes.
Besides this mesocosm experiment, some small experiments are performed in which the underlying processes of production and oxidation of CH4 and the formation of N2O are studied in more detail and in which some experimental procedures are tested. Furthermore, we also determine the fractionation factors (for 13C) of the two main pathways for CH4 production and of the oxidation of CH4.