Carbon Flow And Stock Of Harvested Wood Products In China

Forest harvesting and wood products using change the natural carbon balance betweenforest ecosystem and atmosphere. Harvested wood products(HWP) is an important componentof the terrestrial ecosystem carbon cycle, the carbon stock-change in HWP also is a part ofsignatory nation greenhouse gas(GHG) inventory, and the HWP possess some potentialmitigation of GHG. This paper estimated the Carbon(C) flows and stocks in HWP of ourcountry by using the four accounting approaches which were identified during Dakar sessionin 1998. Carbon emissions and stocks in HWP were estimated for the 1961-2020 period usingfirst order decay method, which was one of lifetime analysis method, and step regressionmethod. In this paper we studied the change of carbon emissions and stocks by the sensitivityanalysis if the parameters and lifetime have changed and further analyzed the socio-economicand forest benefit impacts deriving from the application of the different approaches in China.According to the national conditions and production approach conception, this papersuggested a new hypothesis method:①the use of HWP exported and domestic is similar;②P_j-DOM=P_irw-DOM/CON_irw*P_j.We draw the following conclusions:1) The carbon emissions in HWP in China during 1961-2020 were estimated by using IPCCdefault approach, the stock-change approach, the production approach and theatmospheric-flow approach. The carbon emissions in HWP are growing unceasingly, andthe emissions will be 88.47TGC, 79.18TGC, 81.55TGC and 85.81TGC in 2020,respectively. The carbon emissions in firewood accounts for the biggest proportion amongthe emissions deriving from the firewood, waste during producing processing and HWP inuse. There were no distinct difference in the results of emissions from HWP between fourapproaches, which showed the quantity of HWP exported compared with consumption inChina was small, though the export is growing.2) The HWP is a carbon reservoir in China, and the carbon stocks of HWP are increasingduring 1961-2020. The results are different by stock-change approach, productionapproach and atmospheric-flow approach and they will be 640.03TgC,568.91TgC and 493.62TGC in 2020. There were distinct difference in C stocks of HWP, which showedChina was a large country imported.3) The carbon stocks in HWP in use separately estimated by three approaches during1961-2004. The carbon stocks of wood-based panels and the woodpulp paper andpaperboard started to grow fast in recent decades. The carbon stocks of sawnwood andother industrial roundwood products increased steadily in 2000 ago, but after 2000 thecurve was downtrend, and this mainly due to the inflow of C is less than the outflow.4) Carbon emissions and stocks in HWP were estimated by using different parameters ininternal and foreign countries, its showed that the results of carbon emissions estimated byforeign parameters were more than the results estimated by the internal parameters; whilethe results of C stocks in HWP were in reverse.5) The comparison of the total C emissions and stocks in HWP among different countries in2000 showed that the total C emissions from HWP in China were lower than that in USA.The average increment of C stocks in HWP in use was 24.1TgC·y^-1 which was lower thanthat of USA during 1990-1999.6) This paper suggested a new hypothesis method based on production approach conceptionand our country conditions for decreasing cost. The comparison of results estimated by thenew hypothesis and other's proved the new hypothesis menthod was feasible, but it'snecessary to improve its veracity and research uncertainty farther.7) The sensitivity analysis shows that the results are significantly affected by the conversionfactors of roundwood density, carbon fraction in rotmdwood and the firewood. The carbonfraction in other industrial roundwood products is the most sensitivity factor among thecarbon fraction of each HWP in use. The carbon emissions in HWP may decrease byextending the lifetime. The lifetime of paper and paperboard observably influence theresult of the carbon emissions and stocks in HWR8) The criteria being used in the evaluation of the approaches for the carbon accounting inHWP were discussed in this study. The impacts of trade and production would depend onthe approach selected. In the view of the ultimate results and the accounting perspective,our country may favor stock-change approach.