ISA HK/China --- China Tree News (Contemporary Tree Pit Design) 现代树穴设计

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会员们:

附上图片所看到的, 是国内目前流行的树阵设计。 从表面上来看, 确实是充滿了时代气息, 香港八十年代的设计，有些与此非常相似。

作为一个树艺行业工作者, 我们知道大自然里树木的根部伸展, 往往是由中心发根点, 平均往外辐射到超过了树冠滴水线的切面之外, 作为抗风站穩和吸收水肥。 此外，根部往下的伸展，大部份都长在泥土一米的深度之内, 因为再往下走就没有氧气, 根也长不活了。 在松软的泥土里面, 土壤颗粒之间是充滿空气和水份, 那里的吸收根会长得特别多特别好, 对地上部的养份供应充足, 树体会长势茂盛。 反之者, 如果泥土被压实板死, 土壤颗粒之间的空气和水份都被挤压出去, 泥土的密度大得连新生根都长不进去, 哪树根只会在树干下面团团转, 自然的产生 "盘根效果", 造成上重下轻, 风雨一到, 自然塌下。

看图1和图2, 那四边凸起的 "座椅", 不就等如四张闸刀一样, 把树根的伸展, 牢牢的卡死在 "座椅" 的匡匡内吗？ 树根还可以长到树冠滴水线的以外吗? 哪树冠长大以后, 当受风程度增加以后, 此树能站得稳吗?

再看图3, 树穴以外都铺了一层又厚又重的花岗岩表层, 在它下面的泥土, 颗粒之间的空气和水份, 早就被挤压一光了, 这里的土需要压实平整, 来承托上面花岗岩和行人的重量, 其密度之大, 会令新生根无法往外开展, 造成的效果就与图1和图2一样, 创造了 "盘根效果"。

明白了科学理由以后, 我们要决定我们的设计是想要什麼, 是要一个有 "即时效果" 和 "好看" 的树阵, 还是要一个有安全、长寿和省工省钱去管理的树阵？ 聪明人会怎样决定啊？

谨此致意!

国际树木学会 中华地区分会 会长 暨 创办人

欧永森

美洲顾问树艺师学会 顾问树艺师号 RCA#497 (http://isahkchina.blogspot.com/2010/12/isa-hkchina-rac-in-asia.html)
澳洲顾问树艺师学会 顾问树艺师号 ACM 0412011 (www.iaca.org.au)  
资深树艺师/注册攀树师号 HK-0174BT (http://isahkchina.blogspot.com/2011/03/isa-hkchina-frist-bcma-in-asia.html)
执业树艺师号 IPA-010908 (http://isahkchina.blogspot.com/2010/04/isa-hkchina-tree-news-1441-report.html)
专业调解及谈判学会 注册调解员号 CM-0044 (http://isahkchina.blogspot.com/2012/01/isa-hkchina-mediation.html)

“如果树木在设计和种植时犯错，其护养必然昂贵，而最终也会变成 "不定时炸弹" 。 ”

“速成出来的树木评估员, 只能作出低质量的猜測。 大自然会决定成败。 ”


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Dear Station Members,

Attached is a recent set of photos in a China newspaper, giving admiration to the Tree Pit Design so shown. Particular attention was given to the elevated boarders of the planting area to serve as a seating location for the visitors underneath.

It is noticed by Arborist that the weight of the "seats" would serve as a chopping gate to enclose the viable planting soil to within the less than 1 m x 1 m growing area inside. The weight of the structure would likely wipe out any macrospores in the planting soil, to completely eliminate any air or water pockets, with which the absorbing roots will need to survive. The soil directly under the "seats" would also be compacted to a bulk density so high, that any root penetration to beyond would be impossible. Therefore, the tree roots would be confined to within the tree pit, & may perhaps produce Girdling Roots in a few year's time. Girdling Roots are known to constrict tree trunk to kill tree.

Another effect is that as tree canopy continues to grow & expand, the Girdling Roots underneath have nowhere to spread for safe anchorage. A top heavy structure is then produced. In time, it will come to a point where the wind may topple the tree. This would usually happen in storm. Would the tree owner then claim it an "Act of God" ?

Practically millions of tree pits as shown are now installed in China, as well as in HK. Many will turn into Time Bombs in time.

Good luck to these beautiful Tree Pits in our territory. May they stay safe in our cities, especially in those with typhoons.

best regards,


Sammy Au

Founding President (Station Manager) of ISA HK/China (http://isahkchina.blogspot.com)
Registered Consulting Arborist no. RCA#497 (http://isahkchina.blogspot.com/2010/12/isa-hkchina-first-rca-in-asia.html)
Institute of Australian Consulting Arboriculturists Accredited Member no. ACM 0412011 (www.iaca.org.au)
ISA Board Certified Master Arborist / Certified Tree Worker no. HK-0174BT (http://isahkchina.blogspot.com/2011/03/isa-hkchina-first-bcma-in-asia.html)
Independent Practicing Arborist no. IPA-010908 (http://isahkchina.blogspot.com/2010/04/isa-hkchina-hk-tree-news-14410-report.html)
Society of Certified Mediators and Negotiators Certified Mediator no. CM-0044 (http://isahkchina.blogspot.com/2012/01/isa-hkchina-mediation.html)

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