Tree stand development and carbon sequestration in drained peatland standsin Finland - a simulation study

Drained peatland forests form an important timber resource in Finland. They also form a sink for atmospheric carbon (C) because of the increased growt h and C sequestration rates following drainage. These rates have, however, been poorly quantified. We simulated the tree stand dynamics for drained pe atland stands with and without cuttings over two stand rotations. Simulatio ns were done on four peatland site types and two regions in Finland with di fferent climatic conditions, using recently published peatland tree growth models applied in a stand simulator. We then calculated the amount of C sto red in the stands on the basis of previously published tree-level biomass a nd C content models. Finally, we developed regression models to estimate C stores in the tree stands using stand stem volume as the predictor variable . In the managed stands, the mean growth (annual volume increment) ranged f rom 2 to 9 m(3) ha(-1) a(-1), depending on the rotation (first/second), sit e type and region. Total yield during one rotation varied from 250 to 970 m (3) ha(-1). The maximum stand volumes varied from 220 to 520 m(3) ha(-1) in the managed stands and from 360 to 770 m(3) ha(-1) in the unmanaged. By th e end of the first post-drainage rotation the total C store in the managed stands had increased by 6-12 kg C m(-2) (i.e. 45-140 g C m(-2) a(-1)) compa red to that in the undrained situation. Averaged over two rotations, the in crease in the total C store was 3-6 kg C m(-2). in the corresponding unmana ged stands the C stores increased by 8-15 kg m(-2) over the same periods. A t stand level, the C stores were almost linearly related to the stern volum e and the developed regression equations could explain the variation in the simulated C stores almost entirely.