In April 2020, the USDA Forest Service published Greenhouse gas emissions and removals from forest land, woodlands, and urban trees in the United States, 1990-2018. What makes this annual report unique is that forest carbon estimates are reported for each US state. Data are available in an appendix which lists forest carbon stocks and flux for each state from 1990 to 2018.
Across the US, forests, urban trees, and harvested wood products are the largest carbon sink. Forests offset more than 11 percent of all greenhouse gas emissions last year. This represented 14% of all carbon dioxide emissions.
States in the Pacific Northwest show the great amount of carbon stored in aboveground biomass. The following figure shows the 2020 estimates of aboveground biomass ranked for each US state:
Carbon is not only stored in trees. The report provides values for carbon storage and flux in six different carbon pools:
- Aboveground biomass: Includes trees, shrubs and other vegetation.
- Belowground biomass: 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.
Within US forests, soils account for 56% of all forest ecosystem carbon, followed by aboveground biomass (27%), litter (6%), and belowground biomass and deadwood (5%). The following figure shows the 2020 estimates by region and state comparing the different carbon stocks within each carbon pool:
Visualizing the data by state allows you to see the large stocks of mineral soil and aboveground biomass. In a few of the Lake States (Michigan and Minnesota), you can see the larger contribution of organic soils to total ecosystem carbon.
The appendices available in the new report are a great tool to analyze state-level trends in forest carbon. However, at 511 supplemental tables, you may be swimming with data. The data on carbon stocks in each US state (2019 estimates) is available in this Google Sheet for a speedier analysis.
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