1994 Fiscal Year Final Research Report Summary
The behavior of leaves, branches and stem in a tree crown under mechanical forces such as snow and wind loads
| Project/Area Number |
04660163
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
林学
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| Research Institution | Nagoya University |
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Principal Investigator |
MORIOKA Noboru Nagoya Univ.Fac.of Agri.Prof., 農学部, 教授 (40007943)
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| Co-Investigator(Kenkyū-buntansha) |
KONDO Minoru Nagoya Univ.Fac.of Agri.Assist.Prof., 農学部, 助手 (80153732)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Live branch / Seasonal change / Flexibility of branch / Snow break / Selective cutting / Tree hang-up / Energy absorbtion / Photographic analysis |
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| Research Abstract |
A non-destructive field method was introduced in this research for estimating the Modulus of Elasticity (E) of live branches which is strongly rerated to the tree crown behavior under external loads. This method was very useful in the investigation of the time-dependent factors, such as effect of changes in atmospheric conditions due to the seasons and effect of branch ageing on the flexibility of branches.
The E values of measured three coniferous species all decreased in warm seasons and increased in cold seasons, especially became largest under freezing temeratures in winter. Live branches of Cryptomeria japonica would not fail under loads which they may normally experience in their life time. However, our investigation revealed that the possibility of their branch and stem breakage by snow loads increases when they become stiffend in cold winter. It was also revealed that E values of branches varied with age and species. Variation in the mean annual growth ring width and the specific gravity accounted for changes in the E values of individual branches.
The capacity of live branches to absorb mechanical energy was theoretically and practically investigated. It may contribute to planning and improvement of various tree harvesting operations. Further, the photographic methods were examined for measuring and analyzing the crown shape of standing tree and also branch distribution in the crown.
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