自生する数種の広葉樹の強風に対する順応的形態変化

概要

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In order to clarify the method of expressing tree form, the effect of wind on tree form and the branching system from the dynamic point of view, Strahler's system was applied to Masaki(Euonymus japonicus), Tobera(Pittosporum tobira), Enoki(Celtis sinensis var.japonica), Mochinoki(Ilex integra), Hisakaki(Eurya japonica) which grow at the tip of Miura peninsula in Kanagawa Prefecture. The results obtained can be summarized as follows : The number of branches exponentially decreased with an increase of the order of branch. The ratio of decrease of branches was constant for all the species under weak winds(point B). However, those of Masaki, Tobera and Enoki increased, while that of Hisakaki remained almost unchanged and that of Mochinoki decreased under strong winds(point A). The width and lengths of branches exponentially increased with an increase of the order. Winds checked both thickening and elongation growth for all the species except Mochinoki. Enoki likely accommodated strong winds with an decrease of aspect ratio of branches, while Masaki and Tobera did it with restraint of elongation of higher order branches to the growth check of wind. The mechanical safety allowance S of each branch was proposed. For all the species, it increased with a decrease of the order of branches. The branching system changed to a safer side toward winds.
1994-01-15