Preliminary GHG balances of different drained and rewetted peatland ecosystems in North-eastern Germany

Globally, peatlands store an immense amount of carbon and thus are of large importance for the global climate. Therefore, it is also of uttermost importance to understand the functioning of this carbon sink with regards to anthropogenic influences such as drainage, agricultural use and subsequent rewetting.

In the federal state of Mecklenburg-Western Pomerania in north-western Germany peatlands cover 13% of the total land area. A large proportion of these peatlands have been drained and an estimated 27% of all GHG Emissions of the state originate from drained peatlands. Rewetting of peatlands holds a large potential for the reduction of CO2 emissions thus becoming more and more important in tackling climate change.

In the WETSCAPES project, we aim at understanding the processes of matter turnover in differently managed peatland ecosystems. Here we present preliminary full GHG balances of the first two years of measurements. Results include the balances of coastal flooding fens, percolation fens, and alder forests, of which there is a drained and rewetted one for each peatland ecosystem. The coastal flooding fen was rewetted in 1996, the percolation fen in 1998 and the alder forest in 2003. Fluxes of CO2, CH4, and N2O were measured on these six different sites using the closed chamber method. Additionally, stem fluxes and ditch fluxes were included in the balances where applicable.

Preliminary results show lower CO2 emissions in the rewetted compared to the drained sites; however, this depends strongly on the peatland type. Especially the coastal fens differed only slightly in their CO2 emissions and at the same time showed very high overall CO2 emissions.

Our results show strong variation in GHG emissions of drained and rewetted central European fens in two years with extreme weather, i.e. drought, conditions that are predicted to become more common with increasing global warming. Methane emissions of the rewetted sites were low with only temporary peaks in summer, which again suggests rewetting as the best solution to reduce the climate impact of drained peatlands.