Carbon Balance in the Atmosphere through Forest Growth and the Utilization of Wood Products - By Comparing Scenarios with and without the Use of Forest Products

This study evaluates the atmospheric CO2 balance of Cryptomeria japonica (Japanese cedar), plantations in Japan over a 200-year period, explicitly considering temporal carbon dynamics associated with forest growth, harvesting, decay, and the use of harvested wood products (HWPs). Two simplified systems were compared: (1) a forest utilization system, in which plantations are cyclically managed, harvested every 50 years, and the harvested wood is used for wooden buildings and wood fuel; and (2) a non-forest utilization system, in which forests are left unharvested while steel-frame buildings and fossil fuels substitute for HWPs. The results show that the forest utilization system performs substantially better in climate-change mitigation, with a 200-year atmospheric CO2 balance of 171.6 t-CO2eq./ha, compared with 2,552.5 t-CO2eq./ha for the non-forest utilization system. Sensitivity analysis further indicates that longer building lifetime enhance mitigation by delaying carbon release. The study concludes that cyclical plantation use and long-lived wooden buildings are important strategies for reducing atmospheric CO2 in Japan.