Greenhouse gases are increasing in the atmosphere and causing climate change. Scientist, policy makers, and citizens are trying to determine how to decrease and possibly reverse the emission of greenhouse gases, especially carbon dioxide (CO2). Carbon sequestration, a process where CO2 is pulled from the atmosphere and stored for a long period of time, may be one way to slow or reverse the accumulation of CO2 in the Earth’s atmosphere. Terrestrial sequestration utilizes natural processes in ecosystems to absorb CO2 from the atmosphere and store it in plants, animals, and soil.
[Source: US Environmental Protection Agency (EPA)]
Forests store large amounts of carbon. In the US, forests make up 90% of the US carbon sink and sequester about 10-15% of US CO2 emissions. There are four places where carbon can be stored:
Aboveground – Carbon is stored in the leaves, stems, and other parts of plants when they absorb CO2 from the atmosphere and use it to grow. Trees are very important for carbon sequestration because they live a long time and can store their carbon for many years.
Long-lived products – Wood and other products made from trees still contain the carbon absorbed by the plants that they came from. When a tree is utilized for wood, its ability to sequester carbon is extended, and the carbon is not released until the product burns or decomposes.
Soil – In addition to leaves and stems, trees produce large quantities of roots that contain carbon. Rotting leaves, debris, and soil organisms also contain carbon. In fact, northern forests can sequester twice as much carbon in the soil than aboveground.
Inorganic carbon in soils and rock – Carbon in the soil can slowly develop into other forms, including some types of rock, which are very stable and hold carbon in the soil for very long periods of time.
Forests can be managed to sequester greater amounts of carbon while still providing for wildlife, recreation, wood products, and other uses.
Avoiding deforestation – Deforestation is a major contributor to climate change. Maintaining current forestland is crucial for avoiding additional inputs of CO2 in the atmosphere and for ensuring the ability of the forests to continue sequestering carbon. For example, deforestation, particularly that in the tropics, is responsible for approximately 15-20% of human-caused CO2 emissions.
Afforestation – Forestlands sequester CO2 in larger quantities and for longer periods of time than many other land uses. Converting agricultural, developed, or degraded land to forest can increase the amount of carbon sequestered.
Reforestation – Reestablishing trees on previous forestland is a specific type of management. By maintaining areas as forest, trees will continue to sequester carbon.
Forest management – Slight changes in forest management practices can improve the ability of forests to store carbon while still providing other benefits. Extending the time between harvests, encouraging fast-growing species, and fertilization are a few examples of management techniques that could be used to improve forest carbon sequestration.
- US EPA - Carbon Sequestration in Agriculture and Forestry
- US Department of Energy (DOE) - Carbon Sequestration
- Carbon sequestration in the U.S. forest sector from 1990 to 2010 (Woodbury et al. 2007)
- Forests and Carbon Storage
Last Modified: 03/30/2012