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.