Effects on carbon storage of conversion of old-growth forests to young forests

Simulations of carbon storage suggest that conversion of old-growth forests to youngfast-growing forests will not decrease atmospheric carbon dioxide (CO2) in general, ashas been suggested recently. During simulated timber harvest, on-site carbon storage isreduced considerably and does not approach old-growth storage capacity for at least200 years. Even when sequestration of carbon in wooden buildings is included in themodels, timber harvest results in a net flux of CO2 to the atmosphere. To offset thiseffect, the production of lumber and other long-term wood products, as well as the
span of buildings, would have to increase markedly. Mass balance calculations indicatethat the conversion of 5 x 106 hectares of old-growth forests to younger plantations inwestern Oregon and Washington in the last 100 years has added 1.5 x 109 to1.8 x 109 megagrams of carbon to the atmosphere.