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Emissions of CH4, N2O and CO2 from a Virgin Fen and a Fen Drained for Grassland in Finland
Hannu Nykanen, Jukka Alm, Kristiina Lang, Jouko Silvola and Pertti J. Martikainen
Journal of Biogeography
Vol. 22, No. 2/3, Terrestrial Ecosystem Interactions with Global Change, Volume 1 (Mar. - May, 1995), pp. 351-357
Published by: Wiley
Stable URL: http://www.jstor.org/stable/2845930
Page Count: 7
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Greenhouse gas fluxes (CH4 N2O and CO2) at a managed Finnish peat soil site were compared with those in a virgin fen in 1991 and 1992. The field site was drained about 60 years ago, and as it was used for pasturing and fodder production, the CH4 release by the cattle was estimated on the basis of data in the literature. The annual budgets of the gases were estimated and their GWP values calculated to assess the climatic impact of the current agricultural activity. Methane emission from the field site, 1kg CH4-C ha-1 yr-1. was low, compared with that from the natural fen site, 260kg CH4-C ha-1 yr-1. Annual N2O emission at the field site was 8 and 9 kg N2O-N ha-1 yr-1 in 1991 and 1992, respectively. Summer N2O emission in 1992 from vegetationless soil was five times higher than that from actual grassland. The N2O emissions from natural fen site were low, close to the detection limit. The GWP for the field CH4 release (including cattle) corresponded to 0.3 × 104 kg CO2 ha-1. The GWP for the annual N2O production was 0.2-0.4 × 104 kg CO2 ha-1. while the grassland soil released 2.2 × 104 kg CO2 ha-1 yr-1. In its virgin state the field site may have accumulated 600 kg CO2 ha-1 yr-1. Although there must be a compensating carbon input into the soil in the form of root litter and exudates, a considerable carbon loss occurred (1.5 × 104 kg ha-1 yr-1). The total GWP associated with cultivation was estimated to be 2.6 × 104 kg CO2 ha-1 yr-1.
Journal of Biogeography © 1995 Wiley