FOREST SECTOR IMPACTS FROM CHANGES IN FOREST PRODUCTIVITY UNDER CLIMATE-CHANGE

The consequences of elevated carbon dioxide and climate change on fore st systems and the role that economics could play in timber harvest an d vegetation change have not been addressed together. A framework was developed to link climate change scenarios, an ecosystem model, a fore st sector model and a carbon accounting model. Four climate scenarios were used to estimate net primary productivity (NPP) for forests in th e United States. Changes in NPP were estimated using TEM, the Terrestr ial Ecosystem Model which uses spatially referenced information on cli mate, soils and vegetation so estimate important carbon and nitrogen f luxes and pool sizes within ecosystems at the continental scale. Chang es in NPP under climate change were used to modify timber growth withi n the Aggregate Timberland Assessment Model (ATLAS), which is a part o f the forest sector model (TAMM-ATLAS) used by the Forest Service to e xamine timber policy questions. The changes in timber inventories were then translated into changes in the amount of carbon stored on privat e timberlands using a national carbon model (FORCARB). Regional change s in productivity filter through the forest sector and result in chang es in land use and timber consumption. Long-term changes in carbon sto rage indicate that these private timberlands will be a source of carbo n dioxide for all but the most optimistic climate change scenario.