Carbon storage in eucalyptus and pine plantations in South Africa.

Carbon (C) is stored by plantation forests either when ecosystems with a low C density (such as tropical grasslands) are afforested or when timber is converted to semipermanent products. If the afforestation rate is relatively constant and the plantations are not harvested immediately upon reaching maturity, the amount of C stored in trees as a result of afforestation can be calculated by a simple "static" approximation. Rotation forestry requires a mean C storage method that averages C density over the rotation. Plantation forestry as practiced in South Africa requires a more detailed dynamic approach that accounts for time-varying rates of afforestation and the age-dependence of C accumulation rates in plantations. To determine C storage in products, the output of long-lived plantation products and their C content once all processing losses are accounted for must be known. The South African case study shows that new afforestation stored approximately 2.54 Tg C in 1990, and storage in forest products accounted for an additional 1.15 Tg C. Together, these two activities offset approximately 3.8% of the carbon dioxide emissions from South Africa.