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Carbon in Minnesota trees and woodlands

Quick facts

  • Trees and forests sequester carbon dioxide and other greenhouse gases from the atmosphere.
  • Approximately half of a tree’s dry weight is carbon.
  • Woodlands in Minnesota store on average 75 U.S. tons of carbon per acre.
  • Woodland owners can manage their land for carbon storage, carbon sequestration or both.
  • Forest carbon offset programs typically used by landowners with large acreages provide payment to landowners for the carbon benefits their woodlands provide.
A conifer woodland with a mix of live and downed trees.
Conifer woodland

One of the many benefits that trees provide is removing carbon dioxide from the air. Carbon dioxide is the leading source of greenhouse gas emissions in the United States.

In trees and woodlands, carbon is measured by how much is stored and sequestered. Carbon storage refers to the current amount of carbon in a tree or woodland. Carbon sequestration refers to the process by which trees and other plants use carbon dioxide and photosynthesis to store carbon as plant biomass.

Healthy trees and woodlands increase carbon storage and avoid greenhouse gas emissions. In the United States, trees and forests annually sequester approximately 11% of all greenhouse gas emissions. Understanding how trees and woodlands use carbon leads to a better knowledge of their importance in meeting future global challenges related to climate change.

How much carbon is in a tree?

Graph showing the amount of carbon stored by different tree species. For the same diameter tree, maple, oak, hickory, and beech trees store the most carbon compared to other species.
Approximate aboveground carbon storage for eight different tree species

Approximately half of a tree’s dry weight is carbon. The amount of carbon that is stored in a tree depends on its size, age and species. Carbon is typically measured in pounds or kilograms. A single tree can sequester as much as 10 pounds of carbon dioxide each year.

To determine how much carbon is in a tree, foresters commonly measure a tree’s diameter at breast height (4.5 feet above the ground). For the same diameter tree, maple, oak, hickory and beech trees store the most carbon compared to other species.

Trees are not the only component where carbon is stored in woodlands. Woodlands store carbon in five different pools:

  • Live trees, aboveground: Includes trees, shrubs and other vegetation.
  • Live trees, belowground: Includes coarse and fine roots.
  • Dead wood: Includes standing dead trees and downed dead wood.
  • Litter: Includes leaves and other small woody material.
  • Soil: Includes mineral and organic soil with dead and decaying plant material and insects.

How much carbon is in a woodland?

Graph showing where carbon is stored in forests.
The distribution of carbon in different pools across Minnesota forests

The amount of carbon in a woodland is constantly changing as new trees grow and old trees die. Generally, the amount of carbon stored in a woodland increases as it ages. Carbon in a woodland is typically measured in U.S. tons (where 1 U.S. ton = 2,000 pounds) or metric tonnes (also known as megagrams).

In Minnesota, woodlands average 75 U.S. tons of carbon per acre across all five carbon pools (or 169 metric tonnes per hectare). Most of the carbon found in Minnesota woodlands is distributed in mineral soil and aboveground live trees.

Disturbances will affect how much carbon is stored in a woodland depending on its type and severity. Common disturbances in Minnesota include insects, diseases, windstorms and fires.

To compare how different disturbances impact woodlands, consider two events: a wildfire and an insect outbreak. If a wildfire burns all trees in an area, there is an immediate release of all carbon stored in trees to the atmosphere. This would be an immediate loss of carbon. In contrast, if an insect defoliated all trees in an area and it led to tree mortality over a few years, many trees would remain standing dead and eventually fall to the forest floor. As these dead trees decompose, they will slowly release carbon to the atmosphere typically over the span of several decades or more.

Despite major forest disturbances, carbon storage has increased over the last several decades in Minnesota. Total forest ecosystem carbon stocks in Minnesota have increased from 1,243 million U.S. tons in 1990 to 1,337 million U.S. tons in 2019.

Managing woodlands for carbon

Every woodland is unique in terms of its age, species composition, soil type and history. How you manage a woodland will influence how much carbon it stores and sequesters.

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Carbon in wood products

Exterior of 7 story building made from mass timber.
The T3 (timber, technology, and transit) building in downtown Minneapolis, MN is a seven-story office building made with cross-laminated and nail-laminated timber.

If wood is harvested from a sustainably managed forest, it is a renewable resource. Carbon can be stored in wood products in a variety of forms that can be short-lived (such as paper) or long-lived (such as utility poles or wood-based construction materials).

Harvested wood products in use and solid waste disposal sites represent 4.5% of the total amount of carbon found in the U.S. Wood-based bioenergy generally has a smaller carbon footprint compared to fossil fuels and other renewable energy forms.

The benefits of wood products include carbon storage and lower emissions than fossil fuel-intensive materials such as steel and concrete. Wood is an environmentally friendly building material.

As an example, mass timber buildings (large multi-story buildings made with wood) are increasingly being built across the world. Mass timber buildings are lighter than other traditional buildings commonly designed with steel, are fire-resistant, and can be built more quickly compared to a traditional concrete and steel building. As a result, building codes are being changed or altered that support the construction of mass timber buildings.

Carbon offset markets

A number of forest carbon offset markets have been established that seek to capitalize on the value that trees and forests provide in storing carbon and removing carbon dioxide from the atmosphere. In these markets, corporations and individuals pay for carbon dioxide emissions to offset their own emissions. Landowners are paid for the carbon storage and sequestration their trees provide.

Carbon markets can be categorized as voluntary or compliance-driven. Voluntary markets are typically managed by private entities while compliance markets involve government agencies.

Carbon offset projects are structured so that woodland owners can receive payment through a variety of approaches. These include:

  • Establishing a forest or stand of trees in an area where there was no previous tree cover (afforestation).
  • Reestablishing a forest on understocked or recently harvested land (reforestation).
  • Protecting a forest from being converted to non-forested land.
  • Improving forest management activities to increase carbon storage in the forest or associated forest products.

Most landowners with currently forested lands will enroll in a carbon offset project that improves forest management activities. A private woodland owner can be paid for the value of carbon that their trees store and sequester, but specific details vary across programs and market prices fluctuate. The following conditions are common across many carbon offset markets if landowners seek to enroll.

  • The landowner provides evidence that the property is sustainably managed.
  • The landowner agrees to terms and conditions that the property remains forested over a specified period of time.
  • The landowner has a detailed inventory of the property, including the type, size and composition of tree species in the woodland.

To date, enrollment in a forest carbon offset program has generally been restricted to large landowners (greater than 1,000 acres). Programs continue to evolve and a number of new ones may be appealing to landowners with smaller ownerships. For example, the Family Forest Carbon Program’s goal is to make carbon offset programs accessible to smaller landowners.

Private woodland owners can also receive incentive-based payments that are not a part of carbon markets but may incorporate some aspect of carbon storage and sequestration. These payments can be in the form of a property tax incentive payment, conservation easement or cost share assistance to complete woodland management activities that promote carbon storage and sequestration.

Examples of incentive-based payments for Minnesota woodland owners include enrollment in the Sustainable Forest Incentive Act, 2c Managed Forest Law, and establishing a conservation easement that limits the development of your property.

Matthew Russell, Extension forestry specialist

Reviewed in 2020

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