Abstract:The purpose of this study was to develop a model to estimate the annual available amount of forest biomass resources under profitable forest management in the Nasushiobara city and Kanuma area of Tochigi prefecture, Japan. Economic balances regarding 60-year rotation were estimated based on two types of timber-harvesting systems (conventional operation system conducted by chainsaw and mini-forwarder, and mechanized operation system introducing processor and forwarder), and three types of forest biomass harvesting systems (normal extraction, landing sale, and no biomass extraction) in each subcompartment. The most economical timber and forest biomass harvesting system for each subcompartment was applied.As a result, the number of profitable, nonprofitable, and roadless subcompartments were 1,801; 1,625; and 2,330 of the total 5,756 subcompartments in Nasushiobara city whereas they were 8,940; 3,014; and 20,897 of the total 32,851 subcompartments in the Kanuma area. Then, the annual available amount of forest biomass resources was estimated as the annual supply potential of profitable subcompartments. The annual available amount of the forest biomass resources was 7,805 m 3 /year and 50,313 m 3 /year in Nasushiobara city and Kanuma area, respectively. This available amount meets the annual demand of 6,000 m 3 /year of a 500 kW woody biomass power generation plant planned in Nasushiobara city, and the annual demand of 12,000 m 3 /year of a chip production factory in the Kanuma area.
Abstract:This study examined the effects of a new subsidy system, stand conditions, and forest road network on annual supply potentials and available amounts of timber and logging residues. Excepting a few municipalities, available amounts of logging residues with the new subsidy system were smaller than those with the old subsidy system because the subsidy in the new system was received for the thinning operations with more than 5 ha operation site areas and more than 10 m 3 /ha extracted volumes. Therefore, available amounts are expected to increase as a result of adapting forestry operation site areas and operation systems to the new subsidy system. According to stand conditions, final felling operations with Japanese cypress, larger supply potentials, gentle terrains, road sides, and shorter transporting distances led to a higher ratio of profitable subcompartments. Larger areas are expected to have an increased ratio of profitable sub-compartments. However, almost all profitable sub-compartments were less than 4 ha because forwarding distances FORMATH Vol.13: 20-40, DOI:10.15684/formath.13.20 Received Jul.24, 2013; Accepted Feb.25, 2014 1 Utsunomiya University, Japan, 2 Shinshu University, Japan, 3 Japan Wood Energy Co., Ltd., Japan, * Corresponding Author:aruga@cc.utsunomiya-u.ac.jpEffects of stand conditions on annual availability of logging residue 21 were estimated as average distances from the landings to all grids within the sub-compartments in this study, and larger areas tended to have longer forwarding distances and subsequently, higher forwarding costs. Since forest road networks were relatively well established in Tochigi prefecture, 73% of supply potentials and almost all available amounts of logging residues were within 100 m from existing roads.
This study developed the method to extract production furests based on economic balaiices wi'th considering reg'eneration expenses ror sustainable forest ]nanugement. This study defined production forests as forests where expected revenues at clear cuning surpassed all costs such us haniesting and regeneration expenses, These revenues and costs were estimated based en forest registration and GIS data. The studv site was Kanumu Area of ']bchigi Prefecture. Frorn the results of the double log prices their level fi'om 1981, this model eou]d relativelv accurately est{mate a vEuiety of revenues and costs according to log priees. According to the result on the current conditions with considering reg'eneration costs, only 1,93V'h was erctracted as preduction forest candidates, Thus, the implication js that cx)nducting sustainable forest maiiage]nent at cutting Eige, oo years is difficult based on the current conditions in this area other than 1.93g・6 stands, This could be the reason why 94g,b of the forests are classii'ied as these intended for water and soil ctmseniation although Kanuma area is one of the fa!nous forestrv arens in Tochigi Prefecture. This situation occuiTed due to low log prices and high costs. All costs on smaller areas, subsequently v'oiumes of subcornpartments were much inore expensive than log prices of eyen Hinoki eypress because al1 costs induded indirect costs whichwere almost all fixed costs, the smal1er the areas, subsequently the volurnes, the higher the costs. Therefore, it wiIL be necessary to decrease all costs considerably by Extending ferestn,-operation sites while merging $mall subcornpartrnents.Moreever, estimations that invelved cutting ag'es set at so, 1oo, and 120 years were conducted while eonsidering long-tenn retation management. However, the percentage of preduction-forest candidates increased a little because there was no change in the quulity of logs, subsequently log priccs. This study did not consider effects of changing log prices along with log quality and some kinds of subsidies.Developing the forest-road networks and extending forest-i-operat{on s{tes through the merg'er of small subcompartments should be also examined. The next studv will analvze these effects and which factors have the abi]ity to decrease costs.Kayzvonls/ production forests. economic balances, forest zoning, Kanuina area, sustainable forest nianagement
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