Forest sector impacts from changes in forest productivity under climate change

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