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 coup led with the Carbon Budget Model, we estimate C inventory from 1952 to the present, and project future trends through 2070. Two sets of proj ections are presented, one based on economically derived harvest level s and the other assuming no harvests after 1990. Productive forests se quester an average of 250 Tg C yr-1 from 1952-1987, but projections un der expected harvests assuming no changes in growing conditions indica te 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 la ndfills over the projection period average 75 Tg C yr-1. An estimated 328 Tg C yr-1 would be sequestered if harvesting ceased.