The impact of forestry on the climate.
Why do we fell trees?
Scandinavian forests bind around 55 per cent of our man-made CO2 emissions. So why then is it a good thing to fell trees to produce wooden buildings and other wood products?
One important reason is the ability of trees to act as natural carbon sinks. As with most plants, photosynthesis enables trees to absorb carbon dioxide (CO2). Trees use the most CO2 as they as growing and absorb less CO2 once they are mature. When a tree rots or is burned, the carbon dioxide is released again, but if the tree is felled and used as, for example, construction materials, it continues to act as a carbon sink. An ordinary wooden house/building will, for example, bind around 16 tonnes of CO2 in the wood.
According to the UN Climate Panel, in order to successfully limit global temperature rises to less than 2 degrees Celsius by 2100, we must bind more carbon than we release. We can do this by “capturing” greenhouse gases from the atmosphere and storing them underground or by practising active forestry and using more wood in construction. Producing trees requires little energy and they can replace non-renewable construction materials that emit more greenhouse gases.
The world’s forests are gigantic carbon sinks and to avoid emissions from these sinks, deforestation must be reduced. However, there is big difference between chopping down rainforest, which is often not replaced by new forest, and the forests here in Scandinavia. For each tree felled in Scandinavia, two new trees are planted, which consume more CO2 in their growth phase than mature trees. This means that active forestry helps to bind more CO2 than would be the case were the forest to be allowed to gradually die naturally. According to Trefokus, increased forest production would enable us to increase the amount of captured CO2 from around 1.2 billion tons in 2013 to 1.5 billion tons in 60-70 years.
A number of measures are implemented to ensure that forestry does not reduce a forest’s biodiversity, but instead safeguards all the species that live there. Surveying all of the animal and bird species that live in the forest allows us to ensure that biotopes that are home to rare and endangered species are protected. Requirements have also been produced that set out how much forest must be managed out of consideration for bird species and at what times of the year they must not be disturbed.
Forests cover around 38 per cent of the Norwegian mainland and these areas are home to almost 11 billion trees with a diameter of 5 cm or more. Norwegian forest owners have a good, long history of sustainable management. In fact, Norwegian forests are growing by around 25 million cubic metres of wood each year, while around 10 million cubic metres of wood are extracted annually. Moelven is a major buyer of wood and to ensure that the raw materials we use come from sustainable forestry, we buy certified wood.
Forest protection is important for preserving biodiversity, outdoor recreation and the cultural landscape. 10 per cent of the forest in Norway must be protected and this means that in these areas nature is able to develop free of human influence. However, the climate effects of forest protection are disputed. If the trees are felled before they die, they can be used as a substitute for products produced using fossil resources such as oil, coal and gas, and thus prevent greenhouse gas emissions.
In Scandinavian forests, a lot of carbon is stored in the root systems and in the soil, and during felling CO2 emissions from the soil increase for a period of 10-30 years before the new vegetation again ensures the net absorption of CO2. After felling, forest owners must ensure that new forest is established within three years. This can be done by planting, sowing or natural regeneration due to seeds. Mineral soil can be exposed in these areas in order to ensure that the new forest is established faster, grows better and has higher survival rates. Preparing the land like this disturbs the soil and can thus result in some carbon loss, but at the same time the new forest will be able to bind CO2 again faster.
Although the raw materials from forestry are climate-friendly, forestry does produce greenhouse gas emissions. The emissions come from sources such as the fuel consumed by forestry machinery and logging lorries that carry the wood from the forest to industrial facilities. These emissions are included when calculating the effects of replacing other construction materials with wood. The effects can be further increased by substituting fossil fuel with biofuel, and using electric forestry machinery and logging lorries when these become available.
Sources: Skog – en viktig del av klimaløsningen, Skog.no, Regjeringen.no, Trefokus.