Emission factors and their uncertainty for the exchange of CO2, CH4 and N2O in Finnish managed peatlands

Abstract

This paper summarises the results of several research groups participating in the research programme "Greenhouse Impacts of the use of Peat and Peatlands in Finland", and presents emission factors for peat–atmosphere fluxes of CO₂, CH₄, and N₂O, filling gaps in knowledge concerning the afforestation of organic croplands and cutaways, and improves the emission assessment of peatlands drained for forestry. Forest drainage may result in net binding of soil carbon or net release, depending on site characteristics and the tree stand. Use of peatlands for agriculture (48–4821 g CO₂-eq. m^–2 a^–1), even after the cultivation has ceased, or for milled peat harvesting (1948–2478 g CO₂-eq. m^–2 a^–1) can cause the highest overall emissions. Extremely high CO₂ emissions are possible from peat harvesting areas during wet and warm summers. Afforestation of those peatlands abandoned from cultivation or peat harvesting can reduce the warming impact at least during the first tree generation. Heterotrophic soil respiration may have a systematic south–north difference in temperature response. More data must be collected before the information on peatland forest soil CO₂ emissions can be adapted for different climatic regions in Finland. A test of the model DNDC against measured data showed that DNDC has to be developed further before it can be used in estimating N₂O emissions from boreal peatlands.