Forest Carbon in Wisconsin

This webpage was adapted from a bulletin by the Wisconsin Initiative on Climate Change Impacts Forestry Working Group. You can download and print Bulletin #7: Forest Carbon Overview (PDF).

How do forests store carbon?

• Forests absorb carbon dioxide from the atmosphere through photosynthesis. Forests can also release carbon back into the atmosphere when plants break down sugars for energy (respiration) or through decomposition of organic matter.

• A part of a forest that can store and release carbon is called a carbon pool. Forests store carbon in a few different pools: the biomass of trees (trunks, branches, leaves, and roots), leaf litter, deadwood, and soil.
• The total amount of carbon a forest holds (carbon storage) and the rate at which carbon is added to storage (carbon sequestration) can change with the age, health, and composition of a forest.
• Healthy forests normally take in more carbon than they emit (a carbon sink). Nationwide, forests absorb 10-15 percent of the U.S.’s annual greenhouse gas emissions.
• Forests cover nearly half of Wisconsin and hold over a billion metric tons of carbon. This carbon stock has been getting bigger for decades.
• Changing conditions and additional stressors brought about by climate change can impair the ability of Wisconsin’s forests to continue to sequester and store carbon. For example, after a significant forest disturbance like a wildfire or a pest or disease outbreak, a forest may emit more carbon than it stores (a carbon source). A forest typically becomes a carbon sink again as it regrows.

Forests provide a unique opportunity to address climate change because they can reduce atmospheric concentrations of carbon dioxide while simultaneously providing essential social, environmental, and economic benefits.

Carbon in Wisconsin forests

Wisconsin forests hold over a billion metric tons of carbon—that’s equivalent to the annual carbon emissions from the energy use of nearly 500 million homes. More than half of the carbon in our forests is stored in the soil. In the Chequamegon-Nicolet National Forest (from the drop-down menus select Eastern Region, Chequamegon-Nicolet), for example, approximately 51% of the organic carbon is in the soil, 34% is aboveground in live trees, 6% is belowground in live tree roots, 5% is in leaf litter, 3% is in deadwood, and less than 1% is in understory plants. However, soil carbon is relatively stable over time. Natural disturbances and intentional management can more easily change the carbon stored in living trees.

When looking at the average stand conditions of different forest types in Wisconsin, maple-beech-birch forests currently hold the most aboveground carbon per acre, followed by oak-pine and white pine. Our average jack pine and aspen-birch forests hold the least aboveground carbon per acre—about half as much as maple-beech birch forests.

In addition to the species present, the age of a forest has a big influence on how fast it is sequestering carbon and how much total carbon it has stored. As an example, let’s look at maple-beech-birch forests in the chart below. When they’re 91-120 years old, these forests typically store around 37 metric tons of carbon per acre. When they’re less than 30 years old, they typically hold less than 10 metric tons of carbon per acre. But look how big the jump is between 0-30 years and 31-60 years. As maple-beech-birch forests move between those two age classes, they sequester more than 10 metric tons of carbon per acre. Compare that to the difference between 61-90 years and 91-120 years, which is only about 5 metric tons of carbon per acre. As the forests grow older, they sequester carbon more slowly, but they have a larger total carbon storage.

Because private landowners own more than half of Wisconsin’s forested land, individuals and families have an important role to play in supporting carbon sequestration and storage. In northern Wisconsin, private owners hold 63% of the state’s total forest carbon stock, while state and local ownerships hold 24%, and National Forest land holds 14%.

Wisconsin forests can mitigate climate change

Before the cutover of the late 1800s and early 1900s, Wisconsin forests held much more biomass (living matter) than they do today. That means that if we manage our forests well, we can continue increasing their carbon storage for decades to come. Many actions can promote forest carbon sequestration and storage:

• Maintain and increase forest coverage. Two primary ways to increase forest coverage are to avoid conversion of forests to nonforest uses, and to convert non-forested or previously deforested areas to forest (afforestation or reforestation, respectively). We encourage tree planting in urban areas and renewing forest cover in rural areas. However, converting grasslands to forests may not be recommended because grasslands are also important for storing carbon and supporting wildlife.
• Maintain and increase forest carbon storage. The amount of carbon a forest can store is closely tied to forest biomass, so actions that increase tree growth rates will also increase rates of carbon sequestration. Every forest is unique, so we recommend tailoring harvesting, stocking, and other management practices to optimize forest health and carbon storage in the context of the landowners’ or land managers’ goals.
• Maintain and increase forest productivity. Address invasive species, forest pests, and lack of regeneration due to over-browsing by deer or other factors. Managing these forest stressors ensures that forest carbon stocks can replenish themselves through the successful establishment of young trees after older trees die or are harvested.
• Store carbon in wood-based products. Harvested wood products are a significant carbon pool. The amount of carbon stored in wood products varies greatly depending on the lifespan of the product, energy used in transportation and production, and product disposal. Constructing buildings out of sustainably produced, renewable wood products such as mass timber instead of steel and concrete (which are manufactured using fossil fuels) can also reduce carbon emissions and provide long-term carbon storage in the structures of the buildings.
• Consider enrolling in a forest carbon market. Markets are becoming more easily accessible for Wisconsin forest landowners to receive payment in exchange for increasing the carbon stored in their forests.

If you have questions about forest carbon or other topics related to the changing climate, or if you want to provide feedback on this webpage, contact:

Page last updated April 2025.