The possibility of wood biomass usage by line thinning: The case of the profit sharing forest of Tokyo University of Agriculture

Wood biomass is a renewable resource, which substitute of the petrifaction resource, and now it is receiving attention because of multiple functions, not only an energy resource but also other functions such as environment conservation. But at the practical phase, the wood biomass is difficult to use because yarding of slash is not easy, the cost and income makes reflection each other, and those resources were disposed the forest. So for the sufficient use of wood biomass, we should consider the supply and use method with strategy that considers cost and income. Line thinning is a consolidated thinning method and its cost is low, while slash lies scattered in the vicinity of the yarding road. Thus, it was considered that wood biomass from line thinning could be classified into Vsub(1) (the estimated volume shipped to the market), Vsub(2) (the estimated wood biomass left on the skidding road), Vsub(3) (volume of log remaining in the stand). So the study focuses on the possibility of wood biomass usage in terms of cost and income in the case of line thinning in the shared forest of Tokyo University of Agriculture. The results showed that the estimated total volume of thinned was 402 cubic m, i.e. Vsub(1) was 213 cubic m, i.e. Vsub(2) was 189 cubic m and i.e. Vsub(3) was not considered. Total logging cost excluding cost of yarding road construction was calculated to be 1,535,494 yen, and the cost of logging road was 1,791.000 yen. The final total cost of line thinning was 1,607,594 yen (7,543 yen/cubic m) which was deleted because of subsidy for the thinning and establishment of yarding road. According to the income by log cluster, Vsub(1) was divided into three groups; the first income was minus, the second income was under 4,560 yen (border value of the competition price by other energy that KUBOYAMA (2009) reported), and the third income was between 4,560-13,300 yen. From the site of forest management, we considered the following strategies: The first is that only Vsub(1) is used. But if it is, the cost turned out to be more whereas total income decreased. The second is that, for part of Vsub(1) and all of Vsub(2) for the wood biomass, the thinning cost turned down and the wood group whose income is minus was decreased greatly and other group's income was increased. The third is that all thinned wood is for wood biomass use. If Vsub(2) log could be use as wood biomass, total harvesting cost would decrease and minus log would also decrease. In this case study, it was recommended to apply for wood biomass use, a portion of the logs or total logs due to a few high benefit if there are demands on wood biomass. So if we consider the possibility of biomass use by line thinning in this case, it is effective to choose the strategy that wood from line thinning is for total use of wood biomass.