Calculation of the stem-curve equation of sugi (Cryputomeria japonica) and analysis of timber quality in the Osumi area of Kagoshima Prefecture: A case study of the Kagoshima University Takakuma Experimental Forest
2020
Makino, K. (Kagoshima University, Kagoshima (Japan). Faculty of Agriculture, University Forests) | Oka, M. | Kajisa, T. | Teramoto, Y. | Shiba, M. | Nakajima, T. | Nagahama, T.
At tree-harvesting sites, grading logs are generally made from trees. To maximize the profitability of log operations, wood conversion, which determines the quality grade of logs and timber-yield percentage, largely depends on the adherence to appropriate procedures by forest workers. In this study, we collected data on logs at a production site in real time and assessed their potential applications. Stem-curve equations were developed by measuring trimming length, log length, top end length, and the cutting diameter of each end when the lumber was ready for processing. Next, we analyzed the shape of fallen trees and estimated the timber-yield percentage and quality grade. The timber-yield percentage of cedar wood was consistent with previously documented values in the Osumi area. Furthermore, when the frequency of the quality class was analyzed using the shape ratio as an index, a correlation between the B and C-grade logs and the shape ratio was revealed; however, there was no significant correlation between the shape ratio and A-grade logs.
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