wise use of mires and peatlands - Peatland Ecology Research Group

200 APPENDIX 2Peatland drainage for forestry therefore leadsto■ a steady decrease of the peat carbon store,■ a rapid initial increase of the biomass store,the harvesting of which leads to a typicalsaw tooth curve of the carbon biomassstore (Fig. A2/3), and■ a slow initial increase of the peatland litterstore which eventually, after somecenturies, reaches an equilibrium.The peatland carbon store, being thecombined effect of these processes, variestherefore strongly in time. In the first periodafter drainage, the increase in biomass andlitter stores may strongly exceed the lossesfrom the peat carbon store. As the biomassand litter stores tend to an equilibrium, butthe peat carbon losses continue 72 , thecumulative carbon losses from peat oxidationprevail on the long run 73 (see Fig. A2/3).With respect to gas exchange, the drainageof peatlands for forestry generally leads toan increase in CO 2emissions 75 , a substantialdecrease in CH 4emissions and, depending onpeatland type and type of land use(fertilisation), to a sometimes drastic increasein N 2O emissions 76 .A2.5 THE ROLE OF PEATEXTRACTIONThe effect of peat extraction and subsequentoxidation is similar to that of burning fossilfuels. The peat carbon store is largelytransformed into CO 2. Per m³ of extractedpeat 77 some 50 kg CO 2-C, 11,3 g CH 4-C and4.3 mg N 2O-N are eventually emitted 78 .Efficient drainage in the extraction areas maymaintain high rates of CO 2emissions 79 whileCH 480and N 2O emissions remain fairly low 81 .Fig. A2/3 74 Dynamics of the carbon stores of a tall sedge pine fen site (oligotrophic nutrientstatus) during the 300 years after drainage. Tree stand scenario 1: Total carbon store of anuntreated drained tree stand. Tree stand scenario 2: Total carbon store of a drainedproduction forest. Tree stand stores are shown as a difference between the total (continuousline) and peat store lines (dashed line).