wise use of mires and peatlands - Peatland Ecology Research Group
wise use of mires and peatlands - Peatland Ecology Research Group
wise use of mires and peatlands - Peatland Ecology Research Group
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APPENDIX 21991200010000FensBogskg CO2-C-equivalents ha -1 y -180006000400020000pristinegrassl<strong>and</strong>slightly drainedgrassl<strong>and</strong>drainedtilled pristine grassl<strong>and</strong>low inputgrassl<strong>and</strong>high inputtilled-2000Figure A2/2: Rough estimates <strong>of</strong> the global warming potential <strong>of</strong> fens <strong>and</strong> bogs (in kg CO 2equivalents ha -1 y -1 ) under different types <strong>of</strong> l<strong>and</strong> <strong>use</strong> (compiled by Heinrich Höper 2000). 67A2.4 THE ROLE OF PEATLANDSDRAINED FOR FORESTRY 68 .The effect <strong>of</strong> peatl<strong>and</strong> drainage for forestryis more complicated than that <strong>of</strong> agriculturaldrainage, as various processes withcontrasting effects occur simultaneously <strong>and</strong>the integrated effects differ considerably overdifferent time-scales.As in agriculture, increased aeration <strong>of</strong> thepeat after forestry drainage results in fasterpeat mineralisation <strong>and</strong> a decrease <strong>of</strong> the peatcarbon store. In the boreal zone this aerationmay be accompanied by a decrease in peatpH <strong>and</strong> a lower peat temperature, which mayagain reduce the increased rate <strong>of</strong> peatmineralisation to some extent.As water-logging in <strong>mires</strong> generally preventsan economic level <strong>of</strong> wood production 69 ,peatl<strong>and</strong> drainage aims to increase the woodyield. After drainage, forest vegetation (trees<strong>and</strong> shrubs etc.) takes the place <strong>of</strong> the originalmire vegetation <strong>and</strong> the peatl<strong>and</strong> biomasscarbon store (both above <strong>and</strong> below ground)increases quickly. This store wouldeventually reach a new equilibrium that ismuch higher than that <strong>of</strong> the former mirevegetation. Before this stage is reached thewood is harvested <strong>and</strong> the biomass storereduces substantially again.Peatl<strong>and</strong> drainage for forestry also leads tochanges in the litter carbon store. The “moistlitter” 70 in the mire’s acrotelm is generallyconsidered as part <strong>of</strong> the peat carbon storeas it gradually passes into the catotelm peat.The litter in a drained forest 71 is <strong>of</strong> differentquality <strong>and</strong> can be considered as a separatecomponent. The accumulation <strong>of</strong> litter leadsto an increase in the litter carbon store. Asthis litter accumulates under aerobicconditions, the litter carbon store eventuallyreaches an equilibrium <strong>and</strong> the netaccumulation stops. Depending on thepeatl<strong>and</strong> type <strong>and</strong> the cutting regime <strong>of</strong> theforest, it might take centuries before thisequilibrium is reached.
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