Productivity of America's Forests and Climate Change

A supporting technical document for the 1993 Update of the RPA Assessment

Increasing levels of atmospheric carbon dioxide are expected to alter climate, with potential changes in forest productivity and timber supply. This study analyzes the impacts of elevated carbon dioxide and climate change on forested ecosystems, and the economic feedback on harvest patterns and vegetation change on private timberlands. The analysis used a framework that linked general circulation model output, an ecosystem model, models of the forest sector, and a carbon accounting model. Future climates were described with output from four different general circulation models.

Changes in net primary productivity (NPP) were estimated for temperate and boreal forests in the United States, using three scenarios. Productivity changes reflected ecosystem sensitivities to temperature, precipitation, and nutrient availability. The largest increases in NPP occurred in the northerly ecosystems, and the least response to climate change occurred in timber management types in the southern regions. Increased timber inventories resulted in decreased prices and imports, and shifted production to low cost regions. In this analysis, only the most optimistic scenario shifts future forests from sources of carbon to a carbon sink. The strong demand for wood products in the future dampens any positive growth effects on forests, for all but the maximum scenario.

Joyce, Linda A., ed. 1995. Productivity of America's Forests and Climate Change. General Technical Report RM-271. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station.