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| Nature reserve Stårbatjvare in Arjeplog, Photo: Frédéric Forsmark/Länsstyrelsen i Norrbottens län |
Young forests store carbon. But before there was a young forest there was a clear-cut and before the clear-cut a mature forest. That mature forest stored much more carbon than the young one, due to both trees and soil holding more carbon, and this carbon is released to a large extent when trees are converted to pulp, fuel and wood products. In Sweden over 80% of the forest produce is released to the atmosphere within a short period.
A large part of the carbon in a forest is stored in the soil and when a forest is harvest this carbon ”leaks” from the soil. It takes 10-20 years for forests begin storing carbon again and much longer to store the same amount of carbon that it had before harvesting again. In a landscape or national perspective the average age of forests is reduced drastically by forestry and therefore so is the total carbon storage.
Old forests are beneficial to the climate because they store large amounts of carbon that do not contribute to the greenhouse effect. Research shows that even old forests continue to sequester carbon in trees and in the soil due to slowly decaying organic matter and the Myccorhiza networks. The largest carbon storage is in the boreal forests that are not affected by fires or other disturbances. Read more on the carbon cycle.
Peat consists of accumulated and partially decayed plant debris in wetlands, bogs and fens. When peatlands are drained, they often become fertile and give higher yields. The soil becomes oxygenated, whereby carbon dioxide and nitrous oxide are released. He and co-workers show that a drained spruce forest on peat land acted as a net carbon dioxide source the first 39 years after forestation. Only thereafter, did the uptake of the planted trees balance the previous emissions and became a carbon sink. If the forest is harvested after 80 years and if the biomass is used to produce paper with a short life span, the forest ecosystem becomes a major greenhouse gas source. Meyer and co-workers also concluded that forests on drained peatland probably aren’t carbon sinks.