C- und N-Stofflusse auf Torfstichsimulationsflachen im Donaumoos

C and N-fluxes in fen sites were studied in field experiments after removing the upper soil layer to a depth of 20 cm (A20) and 60 cm (A60), respectively. The different cutting of peat led to a different ground-water table below surface. The study concentrates on the estimate of the N₂O, CH₄, and CO₂ trace gas fluxes. The results show that the fluxes of these trace gases were markedly influenced by the different water regime. The N₂O-N emission amounted to 1.68 (A20) and 5.97 kg ha^-1 yr^-1 (A60). The higher emission from site A60 could be attributed to an increase in N₂O production after a period of complete flooding, and to higher nitrate concentrations due to a low biomass production. Because of the different oxygen availability site A20 was a sink for methane (591 g CH₄-C ha^-1 yr^-1) and site A60 was a source of methane (36 g CH₄-C ha^-1 yr^-1). The seasonal variation of the CO₂ release rates could be explained by changes in groundwater table below surface and soil temperature (r² = 93%). On the basis of this relationship we calculated a peat mineralization of 2910 kg C ha^-1 yr^-1.