臺北市行道樹颱風災害調查與抗風性之探討－－以賀伯、安珀、瑞伯颱風為例

A Study of the Damage Data and Wind Resistance of Taipei Street Trees Using Typhoons HERB, AMBER and ZEB as Case Study

本研究之目的在收集及調查「賀伯颱風」、「安珀颱風」、「瑞伯颱風」侵台期間造成台北市行道樹的災害資料，以探討台北市種植數量最多的十種行道樹之抗風性是否有差異。再由其中挑選倒伏率超過10%以上五種行道樹，配合1973-1980年間栽植在十條道路上的現況調查，進而探討這些樹種是否有更新的需要。結果顯示台北市行道樹之抗風性依樹種不同而有明顯差異，其倒伏率之高低依序為盾柱木（30%）•菩提樹（19.6%）,德克拉橡膠樹（13.7%）'大花紫薇（15.2%）,榕樹（12.3%）,樟樹（7.1%）,台灣欒樹（5%）'白千層（4.1%）•楓香（2.5%）•茄茗（2.1%）;抗風性較差之行道樹有榕樹、德克拉橡膠樹、大花紫薇、菩提樹和盾柱木五種，其中榕樹、德克拉橡膠樹和菩提樹三種氣根多，影響道路景觀。另外，此三種樹種的根嚴重破壞安全島及人行道舖面，可考慮逐步更新為其他抗風樹種。一般市民偏好開花樹種，大花紫薇和盾柱木雖然沒有根破壞路面及人行道舖面之顧忌，但抗風性較差，可選擇風速較小、背風之道路栽植或與其他抗風之樹種混植來增強其抗風性。

The purpose of this thesis is two-folded. Firstly, it is to collect and investigate the data of damage丶 caused by Typhoons Herb, Amber & Zeb in order to evaluate the wind resistance of the densely planted street tree species in Taipei. Secondly, based on the tree growth data of 1973-1980, the author is to select five species of low wind resistance for a field study. It is hoped that through the field study of these trees that have been planted in Taipei for 19-25 years, the author can evaluate their suitability and see if a replacement of high wind resistance trees is necessary. The results are summarized as follows A. Obvious differences were found in wind resistance among the ten most densely planted street tree species in Taipei; they were ranked as follows in terms of easy wind knock-down, Rusty Shield-Bearer(30%), Botree(l 9.6%), Indian Rubber Tree(l 3.7%), Queen Crape Myrtle(IS.2%), 柘g(l2.3%), Camphor(7.1%), Flame Goldrain Tree(5%), Cajuput(4. I%), Fragrant Maple(2.5%) and Red Cedar(2. l %). B. The following five street tree species were found to be less wind resistance: Rusty Shield-Bearer, Botree. Rubber Tree, Queen Crape Myrtle and Fig. Among these species, Botree, Rubber Tree and Fig were not aesthetic because of their brown masses of aerial roots. In addition, their ground roots are so invasive that they often destroy pavement surface. Those three species should be gradually phased out for other more suitable high wind resistant species. In general, flowering street trees are most favorable in Taipei. Both Queen Crape Myrtle and Rusty Shield-Bearer are flowering trees and do not damage street surfaces. To increase their wind resistance, they should be planted on roads with less wind or with other high wind resistant tree species.