Effects of Forest Management Using Pruning and Thinning on Wood Quality and Strength Properties of Sugi Planted in Shimane Prefecture II. Relationship between forest management, and visual grading and bending properties of boxed-heart square timbers

DOI Web Site 2 Citations 38 References
  • Goto Takashi
    Shimane Prefectural Mountainous Region Research Center
  • Nakayama Shigeo
    Shimane Prefectural Mountainous Region Research Center
  • Ikebuchi Takashi
    Forestry Division, Shimane Prefecture Department of Agriculture, Forestry and Fisheries
  • Furuno Takeshi
    Faculty of Science and Engineering, Shimane University Archaeological Research Consultant, Inc.

Bibliographic Information

Other Title
  • 島根県産スギ造林木の材質及び強度特性に及ぼす枝打ち・間伐の影響（第２報）　　心持ち正角の目視等級区分及び曲げ性能と枝打ち・間伐との関係
  • シマネケンサン スギゾウリンボク ノ ザイシツ オヨビ キョウド トクセイ ニ オヨボス エダウチ カンバツ ノ エイキョウ ダイ2ホウ シンモチ ショウカク ノ モクシ トウキュウ クブン オヨビ マゲ セイノウ ト エダウチ カンバツ ト ノ カンケイ
  • Effects of Forest Management Using Pruning and Thinning on Wood Quality and Strength Properties of Sugi Planted in Shimane Prefecture II.
  • Relationship between forest management, and visual grading and bending properties of boxed-heart square timbers
  • 心持ち正角の目視等級区分及び曲げ性能と枝打ち・間伐との関係

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Abstract

The aim of this study was to clarify the effects of forest management such as pruning and thinning on the visual grading and bending properties of boxed-heart square timbers of sugi (Cryptomeria japonica D. Don). In this paper, boxed-heart square timbers sawn from sugi logs cut down at control and at managed forests were investigated after drying for visual grading according to the JAS (Japanese Agricultural Standards for Structural Softwood Lumber) and by full-sized bending tests. The results are summarized as follows : 1) The results of visual grading of timbers showed that while the ratios of second grades for control forests increased, for managed forests those of first grades became greater. The difference between the two was affected by the occurrence of knots on the edge of timber surfaces. 2) Results of full-sized bending testing showed MOE (modulus of elasticity) and MOR (modulus of rupture) values of 7.36 kN/mm2 and 40.7 N/mm2 for control forests, and values of 7.52 kN/mm2 and 43.2 N/mm2 for managed forests, respectively. The lower fifth percentile values with 75% confidence level were 29.1 N/mm2 and 32.1 N/mm2 for control and managed forests, respectively. It was recognized that the variations of bending properties for managed forests tended to be smaller. 3) Concerning the relations between visual grading and MOR, the variations of MOR at each visual grade for managed forests tended to be smaller than those for control forests.

Journal

  • Mokuzai Gakkaishi

    Mokuzai Gakkaishi 55 (3), 146-154, 2009

    The Japan Wood Research Society

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