Why natural Japanese cedar has high flexibility: Understanding material properties of Japanese cedar suitable for magewappa bentwood product.

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05768
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40020:Wood science-related
• Research Institution: Akita Prefectural University
• Principal Investigator: Adachi Koji 秋田県立大学, 木材高度加工研究所, 准教授 (70451838)
• Co-Investigator(Kenkyū-buntansha): 工藤 佳世 秋田県立大学, 木材高度加工研究所, 助教 (10757983)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 曲げ木 / 秋田スギ / 天然スギ / 比弾性率 / 過熟材

Outline of Final Research Achievements

Planted sugi trees (Cryptomeria japonica) with a small DBH (Diameter at Breast Height) - H (Height) ratio tended to have a low specific MOE (modulus of elasticity in bending) and a large amount of bending deflection. This trend was consistent with the material properties of natural sugi, which shows late growth pattern. There was no clear relation between the annual ring width and specific MOE in mature wood. As a result of measuring the material variation of the specific MOE of planted sugi and natural sugi in the radial direction, the increase rate of the specific MOE at the time of transition from juvenile wood to mature wood was about 1.6 times for planted sugi, while about 1.2 times for natural sugi. It was suggested that the growth behavior during the juvenile wood period has a great influence on the material of the mature wood.

Free Research Field

木材加工

Academic Significance and Societal Importance of the Research Achievements

天然スギは人工林スギよりも曲げ木に適しているが、天然と人工の意味する材質指標や生育特性が不明で、人工林主体の今後の森林経営において、曲げ木用の高齢級スギ材の育林方針の設定が困難な状況であった。本研究において、天然スギは未成熟期から成熟期での比弾性率の増加幅が抑制される成長状態であること、現状の人工林でも形状比の小さい林分は曲げやすい立木が多いことが明らかとなり、植栽時にはスギ苗の初期成長の制御、成林の人工林に対しては樹形による選別の有用性を導き出すことが出来た。