Office of Sustainability and Climate, Forest Carbon Graphics

This page contains three graphics that depict forest carbon cycles, fluxes, and stocks. 

Carbon Flux |Carbon in Time & Space

Carbon in forest ecosystems cycles continuously, as plants take up carbon through photosynthesis, and emissions result from decomposition, respiration, or combustion. Carbon may be stored aboveground in live and dead plant material, and belowground in live roots, dead plant material, and soil. Consideration of whether a forest is a carbon sink or source requires an assessment of a particular forested area over time. A forest becomes a carbon sink when an area’s uptake over a given time period is greater than emissions, a carbon source when emissions exceed uptake, or carbon neutral when uptake and emissions are balanced over time.

Management and Disturbance of Forest-Atmosphere Interactions |Carbon Cycle

Forest management plays a key role in the dynamics of forest carbon cycling. Forest management in the forms of thinning, harvest, and prescribed fire, can reduce the risk of high severity disturbance and related carbon emissions, leading to greater ecosystem carbon storage and enhanced carbon stability over the long term. When forest trees are harvested, much of that carbon may be stored as wood products, such as timber used for construction or furniture. These harvested wood products may persist for long time periods. These materials may also be used in the place of other products that would involve greater carbon emissions in their production, such as bricks or steel. Harvested wood products eventually emit carbon in the form of carbon dioxide and methane when they are no longer in use and decompose. Harvested wood biomass produced via forest management can also be used to produce energy. When this biomass is combusted in an energy production facility, some carbon is emitted; many facilities have developed secondary carbon capture mechanisms to mitigate this release. The energy generated in these facilities may be used in place of fossil-fuel energy sources.

The Nation’s Transition from a Wood-based Economy to One Powered by Fossil Fuels |Carbon Stocks

Until around 1915, most products and fuels in the United States came from wood. Forests were harvested to supply this demand, reducing forest carbon stocks from pre-settlement amounts.  After 1915, the economy shifted to a greater reliance on fossil fuels, and forests in some areas regrew, increasing the carbon stored there.