wise use of mires and peatlands - Peatland Ecology Research Group

198 APPENDIX 2Region CH 4emission in kg C ha -1 y. -1bogsfensCanada 53 - 0.8 to + 0.3 - 0.8 to + 0.3Sweden 54 0.8Finland 55 2 to 21 - 0.5 to + 5.0North-east Germany 56 0.6 to 3.5North-west Germany 57 - 1.4 to + 0.3Median 2 0Table A2/8: Methane emissions from drained peatlands used as grassland. Negative valuescorrespond to a net uptake and absorption of methane into the soil.Region N 2O emission in kg N ha -1 y. -1bogsfensFinland 59 0.04 1.2 to 1.5Sweden, Finland (forest) 60 0USA, temperate zone 61 5.7 to 13.1Netherlands 62 2.2 to 13.3South Germany 63 4.2North-east Germany 64 0.6 to 14.0North-west Germany 65 5.0 to 16.0Median 0.02 5.7Table A2/9: Nitrous oxide emissions from drained peatlands used as grassland.Nitrous oxide emissions from bogs are low(Table A2/9) due to the low pH and low totalnitrogen contents. In the more nutrient-richfens, nitrous oxide emissions of up to 16 kg Nha -1 year -1 have been observed, with a medianof 5.7 kg N ha -1 year -1 . N 2O emissions willdepend on the available nitrogen andtherefore on nitrogen fertilization. It isassumed that 1% of the nitrogen applied asfertilizer is emitted as N 2O 58 .Figure A2/2 gives an overview of the globalwarming potential of drained peatlands underdifferent forms of agricultural use. Carbondioxide is by far the most relevant gas,contributing between 85 and 98 % of thecumulative global warming potential of allgreenhouse gases. Intensively used boggrasslands have similar warming potentialsto tilled bogs. Fertilisation and liming ofgrasslands strongly increases peatmineralisation 66 .