A clear cut in the foreground of the spruce study site and an unharvested control area behind. Photo: Mikko Peltoniemi.
Continuous cover forestry and selection harvesting would provide significant climate benefits compared to clear-cutting, as it would avoid significant post-clearing emissions from the soil and the carbon sink of the stand would recover more quickly.
The scenario calculation estimated how greenhouse gas emissions from Finnish forests would change if clear-cutting were to be stopped in drained peatlands and timber production maintained at 2016-2018 levels.
In the scenario where clear-cutting is not allowed, the carbon sink of forests is about 1-1.2 million tonnes of carbon dioxide equivalent (Mt CO2 eq.) higher than in the scenario where clear-cutting is allowed. This amount corresponds to about 10 % of road transport emissions. In the scenarios, the relation between the reduction in logging volume and the increase in carbon sink depends on the chosen forest management method – if harvesting is reduced and a transition to selection harvesting is made, emissions can be reduced by 2-3 Mt CO2 eq. which means up to 30 % of road transport emissions.
The second study investigated the mechanisms of soil GHG emissions and the impact of groundwater elevation in both unthinned drained spruce forests and those subject to selection harvesting. Selection harvesting alone raised water levels only slightly and had no significant effect on carbon emissions. A greater reduction in soil emissions would probably have required not only harvesting but also partial damming of ditches.
The SOMPA project, coordinated by the Natural Resources Institute Finland (Luke), assessed the amount and mechanisms of greenhouse gas emissions in fertile drained peatland forests according to different silvicultural practices. The study combined the MELA model and the SpaFHy-peat hydrological model.
News published on the website of the Natural Resources Institute Finland (Luke) 29.9.2023. Read more at luke.fi website