Biomass Equations

The biomass equations have been obtained from the United States Forest Service Forest Inventory and Assessment (FIA) program. The equations are the same equations used to generate the Common Practice estimate for each Assessment Area (by site class where applicable). Project Developers must use these same equations for their projects.

The form of the equations varies by region. The equations for the Western Coastal United States (Oregon, Washington, and California) incorporate regional equations (Region I) to estimate biomass in the various portions of the above ground portion of the tree, including the stump, the bole, the top branches and leaves. The equations for the remainder of the United States (outside of coastal Alaska and Hawaii, where no FIA data exists or hasn’t been analyzed to date for Reserve purposes) utilize FIA regional cubic volume equations and incorporate the Forest Service’s Component Ratio Method to estimate the volume in the non-bole portions of the tree.

Implementing the Component Ratio Method consists of first calculating gross cubic foot volume of each tree, living and dead. Gross cubic foot volume must then be converted to sound cubic foot volume by subtracting rotten and missing cull volume. Biomass is then calculated for individual tree components for each tree using the Component Ratio Method, with DBH and sound cubic foot volume as inputs.

Steps

• Step 1. Identify the Supersection your project is located in from the GIS Supersection Shape File located below.
• Step 2. Identify the volume equation group that contains your Supersection from the Supersection Volume Equation Groups table located below and extract the volume equation document for that group. The coefficients for the equations are additionally available as MS Excel files for your convenience.
• Step 3. Calculate gross cubic foot volume for each tree, using the equations provided, from a 1 foot stump to a 4 inch top. This will yield the value for VOLCFGRS which must then be converted to VOLCFSND (sound cubic foot volume) by subtracting rotten and missing cull volume in the central stem of each tree.
• Step 4. Download “Biomass Estimation using the Component Ratio Method” (located below) and follow the instructions to calculate biomass for each tree using VOLCFSND from Step 3 and DBH. This FIA document is Appendix J, “Biomass Estimation in the FIADB” of The Forest Inventory and Analysis Database: Database Description and Users Manual Version 4.0 for Phase 2.

Documents

• Supersection Volume Equation Groups Table (July 9, 2010)
• North Central United States Volume Equations (July 9, 2010)
• North Central United States Volume Equations Coefficients (July 9, 2010)
• Northeastern United States Volume Equations (July 9, 2010)
• Northeastern United States Volume Equations Coefficients (July 9, 2010)
• Southeastern United States Volume Equations (July 9, 2010)
• Southeastern United States Volume Equations Coefficients (July 9, 2010)
• Biomass Equations (for California, Washington, and Oregon) (May 13, 2009)
  Reference: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station
• Volumetric Equations (for California, Washington, and Oregon) (May 13, 2009)
  Reference: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station
• Biomass Estimation using the Component Ratio Method (for areas outside of California, Washington, and Oregon) (March 26, 2010)
  From: Appendix J of The Forest Inventory and Analysis Database: Database Description and Users Manual Version 4.0 for Phase 2
• Biomass Coefficients for Jenkins (July 9, 2010)

References

• Investigation into Calculating Tree Biomass and Carbon in the FIADB Using a Biomass Expansion Factor Approach Heath: An Article Describing the Component Ratio Method (March 26, 2010)
  From: USDA Forest Service Proceedings – RMRS-P-56
• The Forest Inventory and Analysis Database: Database Description and Users Manual Version 4.0 for Phase 2 (March 26, 2010)
  From: Appendix J of The Forest Inventory and Analysis Database: Database Description and Users Manual Version 4.0 for Phase 2

Appendix F Documents

The Forest Project Protocol Appendix F contains common practice carbon stock estimates for the Forest Inventory Assessment (FIA) areas across the United States, mill efficiency data for harvested wood products and FIA supersection maps of the U.S. forest regions. Appendix F documents are available independent of the protocol and can be downloaded below.

• Description of FIA Assessment Areas

• Appendix F Assessment Area Data (July 9, 2010)
• Appendix F Mill Efficiency Data (February 2, 2010)
• Supersections Overview Map (February 2, 2010)
• Supersections North Central (February 2, 2010)
• Supersections Northeast (February 2, 2010)
• Supersections Northwest (February 2, 2010)
• Supersections Southeast (February 2, 2010)
• Supersections Southwest (February 2, 2010)

• GIS Supersection Shape File

Note on Appendix F and the FIA Data Tables

Projects should use the most recent version of Appendix F data available on this website. Please note that the FIA statistic is based on the above-ground portion of the tree and is stratified into high and low site classes where it was possible to do so. This will result in the guidance in Section 6.2 related to baseline development being modified to reflect the above-ground portion of the tree only. Guidance for use of the updated Appendix F will be provided in greater detail as soon as possible.

Please contact Policy Team with questions or comments.