Does management improve the carbon balance of forestry?

The long-term carbon balance (CB) of unmanaged forest was compared to the CBs of management scenarios which included cuttings. The calculations were done for a typical forest holding representing mineral soil sites in Central Finland. CB was calculated for twenty-one 10-year periods. Three carbon stores and sub-balances were included in the analysis: (1) below-and above-ground biomass of living trees; (2) forest soil (dead organic matter); and (3) wood-based products. Substitution effects and the releases from harvesting, transporting and manufacturing were included in the CB of products. The no-cutting scenario had the best CB for 120-130 years, after which the cutting scenarios were better. In the no-cutting scenario, the CB of living biomass turned zero after 150 years and the CB of forest soils was still positive after 200 years. At the end of the 210-year simulation period the CB of the unmanaged forest was 0.09 Mg C ha(-1)a(-1) suggesting that old-growth forest is a weak carbon sink. Heavy selective cutting in a mature forest removing half of growing stock volume had a negative influence on the CB of forestry for three decades, after which the balance was better than without cutting. Since the negative and positive effects of cutting have different durations, conclusions about the effect of cutting depend on the length of the time horizon. Because the net effect of cutting is negative in the short term, a short-sighted analysis leads to no-cutting decision when carbon sequestration is maximized, which is a wrong decision in a longer term. When harvested volume was equal to volume increment, the carbon stocks stabilized to 65 Mg C ha(-1) for living biomass, 80 Mg C ha(-1) for soil and 18 Mg C ha(-1) for products.