Heath, Linda (USDA-FS, Durham, NHPO Box 640, Durham, NH, 03824; Phone: 603-868-7612; Fax: 603-868-7604; Lheath@fs.fed.us)

Annualized Forest Carbon Estimates for U.S. National Greenhouse Gas Reporting

L.S. Heath *, J.E. Smith

With the ratification of the United Nations Framework Convention on Climate Change in the 1990’s, like many nations, the United States agreed to develop and make available a national inventory of sources and sinks of all greenhouse gases not controlled by the Montreal Process. The U.S. Environmental Protection Agency (EPA) prepares this inventory. We describe methods used to calculate the annual forest carbon stocks and stock changes used in the 2005 inventory, and present results. Reported results begin in 1990. This method also produces consistent estimates at the State- and regional-level. Our estimates are based on surveys conducted on forests of the U.S. by the USDA Forest Service, Forest Inventory and Analysis (FIA) Program. The surveys are conducted by State, using remote sensing to determine forest area, and field measurements traditionally focused on merchantable timber volumes. We developed a number of techniques to augment the data to estimate carbon stocks. Carbon stock changes are calculated by subtracting consecutive carbon stocks. Discontinuities in past surveys, incomplete data, and changes in evolving survey protocols contribute to complications to this approach. We discuss methods used to overcome these issues. To annualize the data, we assigned carbon stocks to the year data was collected by State and occasionally by owner, using basic interpolation. Results indicate that forests in the coterminous US are sequestering 163 Tg C per year, not including carbon removed from the forest by harvesting.