CARBON TRENDS OF PRODUCTIVE TEMPERATE FORESTS OF THE COTERMINOUS UNITED-STATES

Carbon trends of U. S. timberlands reflect past and current harvesting patterns and forest growth. Using periodic forest inventory data coupled with the Carbon Budget Model, we estimate C inventory from 1952 to the present, and project future trends through 2070. Two sets of projections are presented, one based on economically derived harvest levels and the other assuming no harvests after 1990. Productive forests sequester an average of 250 Tg C yr-1 from 1952-1987, but projections under expected harvests assuming no changes in growing conditions indicate this rate will fall to 60 Tg C yr-1 from 1987 to at least 2050, and then become a C source by 2070. Carbon sequestered in products and landfills over the projection period average 75 Tg C yr-1. An estimated 328 Tg C yr-1 would be sequestered if harvesting ceased.