Recent U.S. Forest Service report describes forest carbon stock changes 1990–2016

The United States is currently in the process of adopting a new approach to forest carbon accounting, the Forest Carbon Accounting Framework (FCAF).

The FCAF seeks to account for changes in U.S. Forest Service forest inventory data or methods over time, identify all appropriate carbon pools in forest ecosystems, address attribution (i.e., disturbances) and land use change, and remove bias and minimize uncertainty as much as is practically possible.

Recently, the U.S. Forest Service used the new FCAF to estimate forest stocks from 1990 – 2016. Results were published in U.S. Forest Service General Technical Report NRS-154 which was authored by 17 scientists associated with the U.S. Forest Service, universities, and other organizations. The authors report that “since 1990, forests in the United States have contributed from 194.4 to 224.5 Tg C∙yr -1 toward the net sequestration of atmospheric carbon” and that “net land use change (nonforest converted to forest after subtracting forest converted to nonforest) accounted for a substantial portion of net sequestration although forest growth (i.e., growth in forest remaining forest) continued to be the major component of net sequestration.”

The abstract for the report follows.

“As a signatory to the United Nations Framework Convention on Climate Change, the United States annually prepares an inventory of carbon that has been emitted and sequestered among sectors (e.g., energy, agriculture, and forests). For many years, the United States developed an inventory of forest carbon by comparing contemporary forest inventories to inventories that were collected using different techniques and definitions from more than 20 years ago. Recognizing the need to improve the U.S. forest carbon inventory budget, the United States is adopting the Forest Carbon Accounting Framework, a new approach that removes this older inventory information from the accounting procedures and enables the delineation of forest carbon accumulation by forest growth, land use change, and natural disturbances such as fire. By using the new accounting approach with consistent inventory information, it was found that net land use change is a substantial contributor to the United States forest carbon sink, with the entire forest sink offsetting approximately 15 percent of annual U.S. carbon dioxide emissions from the burning of fossil fuels. The new framework adheres to accounting guidelines set forth by the Intergovernmental Panel on Climate Change while charting a path forward for the incorporation of emerging research, data, and the needs of stakeholders (e.g., reporting at small scales and boreal forest carbon).”

Reference 

Woodall, C.W., J.W. Coulston, G.M. Domke, B.F. Walters, D.N. Wear, J.E. Smith, H.-E. Andersen, et al. 2015. The U.S. forest carbon accounting framework: stocks and stock change, 1990-2016. General Technical Report NRS-154. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. (http://www.treesearch.fs.fed.us/pubs/49858)