| Summary: | 博士 === 國立臺灣大學 === 森林學研究所 === 90 === Consumption of wood materials alters carbon cycle between forest ecosystems and the atmosphere. The purposes of the study were to 1) analyze and predict the consumption and flow of wood materials and their end-use products between 1990 to 2012 in Taiwan; 2) account for carbon flows and stocks based on consumption of wood materials and utilization of forest products using atmospheric flow and stock change methods; 3) evaluate the effects of consumption of wood materials on the carbon flows and stocks using sensitivity analysis. The consumption of wood materials includes raw material consumption of primary products and raw wastes. The raw material consumption also includes end-use wood products and end-wastes. The major conclusions drawn from the study are as follows:
1.The total domestic consumption of wood materials by the wood-based industries was 8.52 million cubic meters in 1999. Paper and paper products making was the largest of the industrial sectors, accounting for 57.97% of the total consumption. The other sectors included wooden furniture manufacturing, construction and interior decoration sector, woodware products manufacturing, and other wood products manufacturing made up 14.48%, 12.16%, 5.91%, 5.46% and 4.01% of the total wood material consumption respectively.
2.Total domestic consumption of wood materials as end-use products was 7.29 million cubic meters in 1999. Cultural paper was the largest consumer of wood materials, expending 2.46 million cubic meter equivalent of wood, or 29% of the total. It was followed by household paper products (1.07 million cubic meters, or 12.61%), containerboard base (0.73 million cubic meters, or 8.93%), and wood decoration products (0.73 million cubic meters, or 8.63%). The conversion processes turning wood raw materials to end-use products had a utilization rate of 66.23%.
3.The predicted consumption of wood materials between 2000 and 2012 using an econometric modeling method showed that the total consumption of wood materials, fuelwood, lumber, plywood and pulp will increase until the end of the projection (2012). Conversely, the consumption of log and composite board will likely decrease. For the consumption of wood materials in the end-use products, wooden furniture, construction and decorative uses showed a decreasing trend, while woodware, wooden containers, paper and paper products, and other wood products will likely have an increasing trend.
4.The effects of consumption of wood materials and utilization of forest products in Taiwan on the amounts of carbon flows and stocks were estimated by the atmospheric flow and stock change methods. According to the former method, the amount of carbon released into the atmosphere from the consumption of wood materials was 2.29 million metric tons. The amount dropped to 2.27 million metric tons in 1999. This amount is expected to be 2.90 million metric tons of carbon by 2012.The main proportions of carbon release into the atmosphere from the consumption of wood materials and utilization of end-use products in 1999 comprised of wood products in use for 44.96%, wood wastes during manufacturing processes for 41.31%, and short-term wood products use for 12.50%. Based on the latter method, the changes in carbon stocks for the consumption of wood materials and utilization of end-products was 0.13 million metric ton of carbon in 1990, -0.09 million metric tons of carbon in 1999, and -0.49 million metric tons of carbon in 2012.
5.The amount of carbon released into the atmosphere from the consumption of wood materials and utilization of end-products was about 7.46% of all carbon released from fossil fuel burning in Taiwan. This part of the emission was estimated to be between 37.55 and 47.26% of the amount of carbon sequestered by the forests of Taiwan annually.
6.The sensitivity analysis suggests that wood waste from the production processes of the wood-based industries and the service lifetime of the wood products are 2 major factors with greater influences on carbon changes. Thus, by extending the service lifetime of wood products, decreasing wood waste from procession, enhancing waste management, and increasing the proportions of ecological materials (wood materials) in use may help lower the overall carbon emission.
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