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Story | 11/05/2021 06:02:24 | 3 min Read time

The forest is both a carbon sink and a carbon storage

What kind of forest is a carbon sink? And when does a forest become a carbon storage? Read about the key terms related to forests and climate and the role of forests in the fight against climate change.

 

A growing forest is a carbon sink

Trees need light, water and carbon dioxide for photosynthesis. As a result, trees and plants produce oxygen and sequester carbon dioxide from the atmosphere. Forests are carbon sinks, which means that as they grow they store atmospheric carbon dioxide in the trees and soil.

Trees are also sources of carbon: when a tree decays, it releases carbon into the atmosphere as carbon dioxide. Cutting down a forest also releases carbon into the atmosphere, but a regenerated hectare of forest starts to act as a carbon sink after about 17 years, when it again sequesters emissions and acts as a carbon sink throughout its life cycle.

The size of the carbon sink of Finnish forests has varied over the decades, but on average Finnish forests sequester 30-60% of Finland's total annual emissions (mmm.fi).

Annual harvesting of Finnish forests is about 70 million cubic metres per year (luke.fi) and growth is about 107 million cubic metres per year. As long as the growth of Finland's forests exceeds the rate of deforestation, as it currently does when annual natural removals are included, Finland's forests will remain carbon sinks.

 

The carbon sink becomes a carbon storage

When a forest stops growing, it is still a carbon storage. The carbon storage formed by the forest's trees and soil sequesters carbon and therefore does not release it into the atmosphere. Forests are both carbon sinks and carbon storages as they grow.

Although Finland has increased its forest use, the carbon storage of our forests has been growing for decades, as logging has been lower than growth. It is estimated that global warming will increase the carbon storage of Finnish forests by up to 17% (metsakeskus.fi) by 2050.

Products made from wood and wood-based raw materials also store carbon throughout their life cycle and can serve as long-term carbon storage, for example in wood construction. Short-term carbon storages, on the other hand, include milk cartons and paper products.

 

Tackling fossil emissions by increasing the use of wood

The root cause of climate change is carbon emissions from the use of fossil fuels - oil, coal and natural gas. When wood-based products replace products made from fossil materials, one cubic metre of wood reduces about two tonnes of carbon dioxide in the atmosphere.

Wood can also be used sustainably in energy production, reducing carbon dioxide emissions from fossil fuels in the long term. Although burning wood causes emissions, the carbon dioxide released is eventually sequestered back into vegetation and living trees. Leaving wood in logging residues and stumps, on the other hand, would release carbon from litter over decades as a result of decay.

 

Sources:

Natural Resources Institute Finland (LUKE), luke.fi

Metsäkeskus, metsakeskus.fi

Ministry of Agriculture and Forestry, mmm.fi