Lohila A., Aurela M., Hatakka J., Penttilä T., Vuorenmaa J., Nieminen T., Laurila T.
Proceedings of the 14th International Peat Congress
carbon-dioxide, dissolved-organic-carbon, forest, methane, mire
Theme X. Peatland carbon budgets and greenhouse gas (GHG) fluxes
Aquatic export has been recognized as a significant component of the total carbon (C) balance in terrestrial ecosystems. In order to understand the impact of climate warming on the biogeochemistry of C in boreal ecosystems, information on both the greenhouse gas fluxes and the dynamics of the laterally transported C is essential. Continuous measurements of carbon dioxide (CO2) and methane (CH4) exchange with the eddy covariance method have been running at the Lompolojänkkä sedge fen in northern Finland since 2005. In addition, aqueous input and output of dissolved inorganic and organic carbon and dissolved CH4 have been analysed based on soil suction cups, water balance measurements and stream water chemistry sampling. While the methane flux is relatively constant from year to year, the interannual variation in CO2 exchange is considerable. Combining the atmospheric (6 years) and aqueous (3 years) fluxes for the fen ecosystem resulted in an average C sink of about 26 g C m-2 yr-1. The initial results suggest that the import and export components of fluvial fluxes in this fen ecosystem are high, but may cancel out each other. Hence, these fluxes may play a significant role in the C balance of this fen. A small shift in either of the aquatic components may affect greatly the net C balance of the fen.