ISA HK/China --- HK Tree News (Homantin Tree Toppling and Wong Tai Sin Leaning Araucaria)

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 http://isahkchina.blogspot.com , although images are usually not attached due to size. ***

Dear Station Members,

Attached are two sets of news sent in by Station Members recently:

(A) Homantin Ficus Toppling

A 30 year old Ficus toppled around midnight on 30.3.10 to cause property damage in a Homantin housing estate. No one was hurt this time. The incident was blamed on the construction work nearby to cause root damage, which is yet to be verified.

From the photo shown in the newspaper cutting, very little anchoring roots can be seen torn up around the base of the tree after the failure. This may suggest that root development had been poor all the way for this tree to stand up against Wind Loading. The lack of extensive root anchorage could have been caused by the soil compaction of the pavings around. This is a common planting practice in our territory.

Tree does not commit suicide. As long as water uptake & photosynthesis can be maintained by the minimum amount of absorbing roots available, tree canopy will expand despite not growing much anchoring roots. Then the tree may become top-heavy to stand in wind. When the public are applauding to the greening effect, the tree may topple in wind.

It is hard to detect & predict how a tree would stand up against Wind Loading with the common Evaluation Methods. Most Strength Formulae focus on stem breakage, not root friction. Profound knowledge in Wind Mechanics & Tree Biology may be the key for making decision.

How a tree spreads it roots is always hard to tell. Some might say deploying Root Detecting Machines may give the answers. However, most of these machines are designed to map roots in a forest setting, i.e. natural soil without compaction, not paved areas. In urban setting where paving is the identity of a city, radio waves may have difficulties in penetrating through hard surface & compacted layers. Besides, the underground utilities may confuse the readings between roots & conduits. Most Root Detecting Machines can not detect roots smaller than 1/2 inch diameter either.

Sonic Tomographs may not help for root detection either. They are designed to detect trunk & branch decay to a limited accuracy. However, most Tree Failures recorded by ISA HK/China appeared to happen with the roots , not trunk or branch. Planting large tree in a small hole appears to be the culprit.

Experience & knowledge of an Arborist may be the key to judge such a situation. Again, even an experienced Arborist does not have a crystal ball to tell when a tree would fail in what condition of Wind Loading. It remains an educated guess.

Most trees in public area of HK appear to be growing in paved environment. More Tree Failure as a result of it may arise. On prevention, proper Tree Selection & proper Aftercare (including proper pruning) may be the key. Trees should be in the hand of Arborists to stay sound.

(B) Wong Tai Sin leaning Araucaria

If compared to the Maryknoll Ghost Pine, this Wong Tai Sin Araucaria is younger as shown in the photo, although more leaning.

A resident complained to the media that this tree is becoming a Time Bomb, & action should be taken by the tree owner immediately. The politician commented by putting Public Safety as a priority, but treatment should also be given without delay if the tree has any conservation value. From these words, no clear & positive protocols are given as to what to do with the tree.

A scenario may arrive at this. If the tree is retained but fails later, the tree owner would get the blame. If the tree is removed for this & that reason right now, the tree owner may be labeled a Tree Murderer.

Then what can the tree owner do to stay proper ??

best regards,

Sammy Au
Station Manager

"If a tree is not designed, installed, maintained & inspected properly, it is likely to become a liability rather than an asset."

"Trees are good for the community. Trees need care like human beings. Arborists are the Tree Care Professionals."

ISA HK/China --- HK Tree News (Arborist joining the Maryknoll 'Ghost Tree' Memory Group

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 http://isahkchina.blogspot.com , although images are usually not attached due to size. ***

Dear Station Members,

ISA HK/China has noticed from the newspaper report sent in below that Arborists are joining the 'Hundred Year Tree' Group which appears to be involved with pursuing administrative liabilities of the Maryknoll Araucaria Felling, & tree preservation in schools in HK.

Please note that our Station Members will be joining any group in their own capacities & at their own risks. ISA HK/China will not get involved with politics in accordance with current ISA policies & practice. Station Members can not & will not represent ISA HK/China or ISA in any capacity without prior written approval.

Please note the ISA Mission of:

"Through research, technology, and education promote the professional practice of arboriculture and foster a greater public awareness of the benefits of trees."

ISA HK/China will faithfully follow ISA Mission to serve our territory of HK, Macau, Taiwan & China without deviation.

Thank you for your kind attention.

best regards,

Sammy Au
Station Manager

"If a tree is not designed, installed, maintained & inspected properly, it is likely to become a liability rather than an asset."

"Trees are good for the community. Trees need care like human beings. Arborists are the Tree Care Professionals."

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29/03/2010

瑪利諾「鬼樹」未被移除前是學校地標。

「鬼樹」枉死校友究責

本文重點

50萬公帑下落未明

設關注組正視問題

瑪利諾修院學校上月移除俗稱「鬼樹」的異葉南洋杉餘波未了。該校多名校友昨日出席「鬼樹」紀念會，堅持為死得冤枉的「鬼樹」討回公道，包括研究提出司法覆核，要求法庭徹查發展局及古物古蹟辦事處在事件中有否失職。校友及保育人士又宣布已獲得多位專業人士支持，成立新的保育樹木組織「百年樹木」，關注全港學校內樹木安全問題，希望阻止再有位於校內或私人土地上的珍貴古樹被無理傷害。

近廿名瑪利諾校友昨日在紀念會上觀看「鬼樹」生前片段及寫上心意卡，部分校友更為失去「老朋友」飲泣落淚。

50萬公帑下落未明

「百年樹木」會長朱茵強調，雖然「鬼樹」被砍已成事實，但仍有一連串問題待當局解答，包括當初批予保護「鬼樹」的五十萬元公帑何去何從、古蹟辦○八年將瑪利諾校舍列入法定古蹟時，有否登記校內樹木及其他受保護物件，以及有否明確通知校方在古蹟之內挖掘或砍伐樹木皆需申報等，「如果無嘅話就係古蹟辦失職」。她又指，由於古蹟辦不在申訴專員公署調查範圍內，故不排除透過司法覆核為「鬼樹」討回公道。

蘇國賢批評當局樹木保育工作混亂，經常發生好樹無故被砍，壞樹無人理會的情況。

朱茵表示「百年樹木」有意為學校提供免費樹木評估服務。

有參加「鬼樹」追思會的人士有悲慟之情。

設關注組正視問題

朱續稱，「百年樹木」關注組將協助全港學校正視校內樹木問題，避免再發生樹木枉死事件。該組織已獲得多位樹藝師、建築師及園景師等專業人士支持，若有學校對校內樹木安全或其成長狀況有疑慮又不懂處理，可為其提供免費評估。

長春社總監兼「百年樹木」顧問蘇國賢則批評當局巡查樹木工作馬虎，至今亦沒有建立塌樹意外資料庫，導致樹木保育工作混亂：「當局成日話全港幾百萬棵樹好難理，其實只要簡單搜集一下資料，就可以知道鳳凰木等幾種樹最易冧，縮窄巡查範圍。」

他又擔心當局規定只要出席十二小時課程就獲頒樹藝證書的做法，會導致前線樹木巡查員及外判工人質素參差，要求當局盡快立法監管。

發展局發言人回應指，已要求瑪利諾校方為今年一月在未有按要求通知古蹟辦下，進行渠務工程一事提供詳細資料，局方正研究該等新資料及適當跟進。