Dynamics and potentials of carbon sequestration in managed stands and wood products in Finland under changing climatic conditions

Carbon (C) sequestration was studied in managed boreal forest stands and in wood products under current and changing climate in Finland. The C flows were simulated with a gap-type forest model interfaced with a wood product model. Sites in the simulations represented medium fertile southern and northern Finland sites, and stands were pure Scots pine and Norway spruce stands or mixtures of silver and pubescent birch. Changing climate increased C sequestration clearly in northern Finland, but in southern Finland sequestration even decreased. Temperature is currently the major factor limiting tree growth in northern Finland. In southern Finland, the total average C balance over the 150 year period increased slightly in Scots pine stands and wood products, from 0.78 Mg C ha(-1) per year to 0.84 Mg C ha(-1) per year, while in birch stands and wood products the increase was larger, from 0.64 Mg C ha(-1) per year to 0.92 Mg C ha(-1) per year. In Norway spruce stands and wood products, the total average balance decreased substantially, from 0.96 Mg C ha(-1) per year to 0.32 Mg C ha(-1) per year. In northern Finland, the total average C balance of the 150 year period increased under changing climate, regardless of tree species: in Scots pine stands and wood products from 1.10 Mg C ha(-1) per year to 1.42 Mg C ha(-1) per year, in Norway spruce stands and wood products from 0.69 Mg C ha(-1) per year to 0.99 Mg C ha(-1) per year, and in birch stands and wood products from 0.43 Mg C ha(-1) per year to 0.60 Mg C ha(-1) per year. C sequestration in unmanaged stands was larger than in managed systems, regardless of climate. However, wood products should be included in C sequestration assessments since 12-55% of the total 45-214 Mg C ha(-1) after 150 years' simulation was in products, depending on tree species, climate and location. The largest C flow from managed system back into the atmosphere was from litter, 36-47% of the total flow, from vegetation 22-32%, from soil organic matter 25-30%. Emissions from the production process and burning of discarded products were 1-6% of the total flow, and emissions from landfills less than 1%.