When a plant photosynthesises it takes carbon dioxide from the air and, combining it with water, produces sugar and oxygen. The sugars produced are used as energy and to make new materials as the plant grows. In this way carbon from the air is converted into carbon stored in plants. For this reason forests act as ‘carbon sinks’.
In this way, USA forests offset about 15% of the country’s carbon emissions from fossil fuel combustion.
If a forest is left to its own devices, carbon dioxide is removed from the air as plants grow and released back into the atmosphere when dead wood decays. But in reality many forests are managed for wood production. The wood is removed from the forest and used for furniture, doors, building etc.
So the wood in our houses stores carbon which was removed from the atmosphere when the plant photosynthesised. Understanding this can help forest management.
In the mid 20th century wood production was high so the amount of carbon stored in harvested wood products was increasing. However, when this wood is disposed of it decays on the landfill site and releases carbon dioxide. In the Northern USA the stock of carbon contained in wood products is actually declining because more wood is being discarded than produced.
A recent paper in Carbon Balance and Management states that American forest managers don’t have the information they need to meet national goals for managing climate change. The authors found that when information about wood production from a particular forest is available this helps guide management practices, and they suggest how such information can guide management decisions across the US.
So the wood in your house is a carbon sink, but of course your house is probably built on land that was once forest – a greater carbon sink than your furniture – and is full of electrical appliances powered by fossil fuels. But we need houses, and management must be based on what we need from forests not just on the carbon balance. Another trade off between needs and climate change.
Stockmann, K., Anderson, N., Skog, K., Healey, S., Loeffler, D., Jones, G., & Morrison, J. (2012). Estimates of carbon stored in harvested wood products from the United States Forest Service Northern Region, 1906-2010. Carbon Balance and Management, 7 (1) DOI: 10.1186/1750-0680-7-1
