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檜皮採取がヒノキの直径成長に与える影響
門松, 昌彦;山本, 博一;坂野上, なお;古賀, 信也
Permalink : http://hdl.handle.net/2115/49959
KEYWORDS : ヒノキ;檜皮;剥皮;胸高直径;成長;Chamaecyparis obtusa;hiwada;bark decortication;DBH;growth
Abstract
国指定の重要文化財の中には、屋根にヒノキの樹皮である檜皮を葺いている木造建造物は多い。しかし、檜皮剥皮がヒノキの成長や材質に及ぼす影響については、ほとんど報告されていなかった。そこで、檜皮採取がヒノキの直径成長に与える影響を調べた。剥皮された個体の胸高直径は早くて剥皮後2年で剥皮前の胸高直径までに回復し、剥皮後6年で8割の剥皮木の胸高直径が剥皮前の胸高直径以上になった。剥皮後9年間で、剥皮木の胸高直径の成長量と非剥皮木の成長量とに有意な違いは認められなかった。したがって、熟練者が檜皮採取を行うならば、剥皮が胸高直径の成長に悪影響を及ぼすことはないと推察される。
In Japanese important cultural properties, many wooden buildings are roofed with Japanese cypress (Chamaecyparis obtusa) bark, hiwada. However, there are few reports of the effect of hiwada harvest on the growth and wood properties of the cypress. We studied whether bark decortication for hiwada production would affect diameter increment of cypress trees. The diameters at breast height of some decorticated trees recovered to their pre-treatment diameters in two years, and 79 percent of the treated trees had diameters greater than those before the treatment six years after the treatment. For nine years after decorticating, there were no significant differences in the diameter increments between the treated trees and the untreated trees. We concluded that diameter growth might not be affected by the decortication of bark for hiwada production if done by highly skilled workers.
In Japanese important cultural properties, many wooden buildings are roofed with Japanese cypress (Chamaecyparis obtusa) bark, hiwada. However, there are few reports of the effect of hiwada harvest on the growth and wood properties of the cypress. We studied whether bark decortication for hiwada production would affect diameter increment of cypress trees. The diameters at breast height of some decorticated trees recovered to their pre-treatment diameters in two years, and 79 percent of the treated trees had diameters greater than those before the treatment six years after the treatment. For nine years after decorticating, there were no significant differences in the diameter increments between the treated trees and the untreated trees. We concluded that diameter growth might not be affected by the decortication of bark for hiwada production if done by highly skilled workers.
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