Monday, March 7, 2011

ISA HK/China --- PTB (Episode 3 : Proper Diagnosis before Risk Assessment)

国内朋友请使用翻译软件阅读本文 (。

*** Our weekly Station Mail is for the information of Station Members only, but Station Mail has given up copyright & can be freely circulated. For administrative reasons, comments from outsiders are usually not entertained & may be circulated within our system locally & overseas. Please note Station Mail is sometimes given in Blog at , although images are usually not attached due to size. ***

Dear Station Members,

Many a times Arborists in our territory are asked to conduct Tree Assessment. Many of the "Tree Assessors" are also newly certified, getting the job from an employer who would look for the cheapest alternative. A standard Tree Assessment "Form" would be used to fill in observational data & be given a rating, & then Treatment would be written down in accordance with the knowledge & experience of this "Tree Assessor". Details of the Treatment is usually not required, e.g. how many percent for Crown Reduction, at where & why. Symptoms may be recorded but not investigated in any details.

Diagnosis is perhaps the domain that most Certified Arborist (CA) candidates fail in the exam in our territory. To conduct a proper diagnosis, the Diagnostician has to be knowledgeable in Tree ID, Abiotic & Biotic Disorders, Pests, Site Condition, Management History & Client's Expectation. He would need sharp observation & has adequate experience to identify the problem, & evaluate for a solution. Not all Tree Disorders can be treated in an urban area. Tree Removal should also be taken as a last resort, when all other alternatives have failed.

Some of the Symptoms in trees can appear similar. For e.g., water deficit & root disease would have the same outlook of Dieback in the canopy. Sunburn & Anthracnose can be confused with each other. Herbicide Damage & Leaf Disease also look similar. It's up to the Diagnostician with his inquisitive mind to find out what's wrong, & to propose a Treatment. And Treatment without Diagnosis is Malpractice.

To conduct proper Diagnosis, reciting the "CA Study Guide" is not enough. There are dozens of books in ISA on the topic, plus regular research coming out in every journal of Urban Forestry & Arboriculture. However, how many of our CA would bother to review hard into them? With an ignorant client & an immature supervision system, many incompetent "Tree Assessors" would get away to cut trees down without justification, & to provide incorrect Treatment without the right cause. Our urban forest would inadvertently diminish in this manner. Or is this what the Tree Owners would ultimately want : Out of sight, out of mind?

It is necessary to have an acceptable public body to supervise our trees under common eyes, & to ensure our Tree Planting is sustainable. ISA HK/China has proposed the Public Tree Board , (PTB, to get everybody involved. One good thing about the PTB is that it may divert political pressure from other heated topics in our society. PTB should serve a general purpose of social harmony.

Major western municipalities have their own PTB. PTB appears to be part of the advanced civilization. We wonder when our territory would have the first PTB established anywhere?

In China, perhaps?

best regards,

Sammy Au
President / Station Manager
Registered Consulting Arborist no. RCA#497 (
Independent Practicing Arborist no. IPA-010908 (
ISA Certified Arborist / Certified Tree Worker no. HK-0174AT (

"Providing treatment without in-depth diagnosis & research support is professional misconduct. "

"Casual tree assessor delivers wanton tree assessment. Mother Nature makes the rules."


在树艺界,很多时候树艺师是被要求对树木进行评估。很多最近才考获注册的“树木评估员”,从那些只考虑选取廉价服务的雇主上取得“评树“工作。这些“树评员” 根据自己的知识和经验,便將所得的观测数据及评定等级,及树疗方法填入一張标准的树本评估“表“内。通常都不须要填写非常详细的治疗方法,例如:树冠要减少几多百分比,要在那里减少,及为何要减少。症状可能会被纪录,但缺乏周详调查。

'诊断' 可能是一個範籌引致大多数 "注册树艺师 " 考生于牌照考试中不及格。要进行适当的诊断,诊断者必须在对辨树、非生物和生物病理、虫害、现场条件、管理历史与客户的期望等都要有所认知。他需要有敏锐的观察力和丰富经验來肯定问题所在, 从而评估解决的方案。于市区笵圍內,並非所有树害病都可以得到治疗。誠然,当所有其他办法都没有奏效,移走树木才应是最后手段。


這需要有一个認受性的公共机构在共同眼睛下去监管我们的树木,及确保我们的植树是可持续的。太分会已提倡設立 公共树木评议會 (PTB,让所有人都可加入参与。PTB 的好處是從其他热门社會话题中転移政治压力。PTB 是以諦造社會和谐而存在的。

大多西方主要城市都已有自己的 PTB。PTB 似乎是先进文明的一部分。我们很想知道,我们何时何地才可以有属於我們地区的第一个PTB ?

也許, 在中国?


国际树木学会 中国地区分会 会长
顾问树艺师号 RCA#497 (
独立执业树艺师号 IPA-010908 (
注册树艺师 / 注册攀树师号 HK-0174AT (



(以上由罗叶明 注册树艺师号 HK-0538A 翻绎。一切内容以英文版本为准。)