When a tree grows by a cubic metre or so, it binds around 900 kilos of carbon dioxide. Carbon is bound most effectively by trees that are in a good growing phase – that is, trees that are 20 to 60 years old.
A forest as a whole is huge store of carbon. The carbon storage of an old forest is multiple times that of a young forest. The largest amount of carbon is stored in organic matter in forest land.
Forest management accelerates forest growth
Forest growth in Finland was 107 million cubic metres in 2019, and a total of 71 million cubic metres of wood was felled – markedly less than the annual growth.
Forest growth in Finland has accelerated significantly over the last 50 years. In the 1980s, the average growth per hectare was 2.4 cubic metres. The growth rate has since doubled and is currently 4.8 cubic metres per hectare.
Forest growth has been accelerated by global warming and, above all, good forest management. When brushwood is cleared and young forests are thinned, the remaining trees grow more quickly.
The carbon remains in the sawn timber
Wood used by sawmills is the most valuable part of the log. It is around 40 per cent of the annual felling volume.
Around two cubic metres of wood raw material is required for a cubic metre of sawn timber. The sturdy parts of a trunk are used for sawn timber. The chips generated during sawing are used to produce pulp, and sawdust and bark are used to produce bioenergy.
The carbon sequestered in a tree remains in the sawn timber. The amount of carbon in one cubic metre of sawn timber is around 200 kilos.
Each house built of wood is a small store of carbon. Around 4,000 kilos of carbon is sequestered in a detached house of 100 square metres.
Wood replaces fossil raw materials
Wood products have a unique ability to bind carbon. The longer buildings are in use, the longer the carbon stays out of the atmosphere.
The use of wood reduces carbon emissions from fossil fuels and fossil-based products. This phenomenon is known as the substitution effect. Sawn timber has a high substitution effect.
Metsä Group aims to increase the amount of carbon sequestered in its products by 30 per cent by 2030. This goal can be achieved by producing long-term wood products, such as sawn timber and engineered wood products, which store carbon throughout their lifecycles.
The sawmill to be built in Rauma will significantly increase the manufacture of wood products.
Riikka Joukio, Metsä Group's Director of Climate and Circular Economy, has been used as an expert in the text.
Sources: Luke Natural Resources Center, Puuinfo, Metsä Group