Storm-Vulnerable Trees

The Tree Management Programme of the National Parks Board (NParks) describes the inspection of trees "along major roads or  areas with high human activity" at least once every 12 months. Crown reduction  pruning was conducted when necessary. [1]

Furthermore, NParks was on an exercise to remove/replace storm-vulnerable trees and advising other public agencies, such as the Singapore Land Authority (SLA) and Housing and Development Board (HDB), to do the same. The only storm-vulnerable species publicised was the Albizia tree (Falcataria moluccana), which is fast-growing and could easily exceed 20m in height. But its wood is soft and prone to breaking during storms. In addition, they are shallow-rooted and thus susceptible to uprooting. There should be other storm-vulnerable species listed, but unfortunately, they were not shared in the article.

Photo by Shin Min Daily News

Almost 4 years ago (27 Sep 2012), a NSman on in-camp training was crushed by a tree and was subsequently pronounced dead at the hospital he was taken to [2]. The incident took place at the entrance of the Ama Keng Training Area in Lim Chu Kang. If a certified arborist (CA) were to have carried out tree inspection on that tree, the CA could have recommended the removal of the offending tree. Based on the photo, the tree appeared to be an African tulip tree (Spathodea campanulata), detailed further below.

In an "after" photo where SLA selectively removed Albizia trees at Jalan Anak Bukit, (near Bukit Timah Hill), African tulip trees were observed to be left behind and intact. [1] The site of the "after" photo was visited last week and it looked very different due to road expansion works.

 "After" photo after an exercise by SLA to remove Albizia trees. Probably taken in 2012, from NParks website [1].

 Road widening in the target area of storm-vulnerable trees, which include Albizia and African Tulip trees. Photo taken on 11 Sep 2016.

African tulip trees near the edge of the road expansion.

Land Transport Authority (LTA) notice on the road widening.

There are nine tree species identified as being invasive in Singapore. A common attribute of these invasive tree species is that as compared with non-invasive species, they have only 54% of the mean wood density. It should be noted that other than Falcataria moluccana and some outlying individuals of Cecropia pachystachya, "no attempt has been made to control the other species." [3]

The following are four of the invasive tree species that could be considered "storm-vulnerable", which could be removed from roadsides, forest edges, parks and high-traffic areas:

a. Acacia auriculiformis (Ear-leaf acacia)
It could grow in nutrient poor soil as it has nitrogen-fixing bacteria associated with its roots. Fast-growing and drops a lot of leaves. Roots grow shallow, spreading and densely matted, which makes it suitable to stabilise eroding land.

b. Cecropia pachystachya (syn. Cecropia peltata) (Trumpet tree)
In Singapore, this tree is viewed as a weed and is short-lived [4]. It has hollow stems, which is inhabitaed by ants.

c. Falcataria moluccana (Moluccan albizia)
Perhaps the fastest-growing tree in the world [4]. Like the Acacia, it is capable of fixing nitrogen from the air. Considered a weed and hazard due to its soft, brittle wood, and shallow roots.

d. Spathodea campanulata (African tulip tree)
Similar to the Albizia tree, the wood of the African tulip tree is soft, tends to become hollow, and drops their branches over time. The roots grow shallow and is more likely to uproot during storms.

Table 1. Invasive tree species in Singapore with their common names
Acacia auriculiformis    Ear-leaf acacia
Cecropia pachystachya    Trumpet tree
Falcataria moluccana    Moluccan albizia
Leucaena leucocephala    Lead tree
Manihot carthaginensis    Ceara rubber tree
Muntingia calabura    Jamaican cherry tree
Piper aduncum    Spiked pepper
Spathodea campanulata    African tulip tree

Table 2. Potentially invasive tree species (not necessarily storm-vulnerable) identified in the paper [3]
Hevea brasiliensis    Para rubber tree
Andira inermis    Brown heart tree
Ptychosperma macarthurii    Macarthur palm
Elaeis guineensis    Oil palm
Ficus religiosa    Bodhi tree

Reference:
1. National Parks Board Tree Management Programme (https://www.nparks.gov.sg/news/2013/1/nparks-tree-management-programme), 1 Jan 2013, Last updated on 20 Nov 2014,
2. Jalelah Abu Baker and Lim Yan Liang, NSman's death: Tree was checked in April, Asiaone (http://news.asiaone.com/News/Latest+News/Singapore/Story/A1Story20120929-374484.html), 29 Sep 2012
3. Nghiem, L. T. P., Tan, H. T. W. and Corlett, R. T. 2015. Invasive trees in Singapore: are they a threat to native forests? Tropical Conservation Science Vol.8 (1): 201-214
4. Tee et. al., Trees of Our Garden City, 2nd ed, 2009

The man behind the design of Seiwaen (Singapore's Japanese Garden)

Kinsaku Nakane on the left with his son Shiro on the right.

Seiwaen opened on 16 Feb 1973, the largest Japanese garden outside of Japan at that time. The garden was built on a man-made island in the middle of Jurong Lake, adjacent to Yu Hwa Yuan (Chinese Garden). Designed by Professor Kinsaku Nakane, Japan's leading landscape designer, the garden took four years to complete. Originally part of a swamp, the Chinese and Japanese Gardens are two of three man-made islands at Jurong  (the third one being Jurong Country Club... which is more of like an extension rather than an island).

This large strolling garden was constructed according to the gardening techniques that prevailed from the Muromachi Period (1392 - 1568) to the Momoyama Period (1568 - 1615). The architecture was based on post-war style.

Funding came from Singapore and Japanese governments as well as the local Japanese organisations at the cost of $3 million. The garden symbolises the peace and prosperity between Singapore and Japan. Notable landmarks are the 4 metres (13-foot) tall Kasuga stone lantern that overlooks a lake and Torii gates at the "guesthouse" building.

The garden was closed since 2001 and in 2003, after a review, closed for renovations and reopened on 15 July 2007. As part of the effort to re-invent itself, large amount of earth was brought in to terra-form the land; artificial hills were created.

Nakane passed away at the age of 77 on 1 March 1995 in Kyoto. Apart from designing gardens in Japan, China and in the West, he was the President of the Osaka University of Fine Arts and Nakane Garden Research, which is still in operation today with his son Shiro at the helm. [URL: http://www.lares.dti.ne.jp/~nakane/index.html]

The Tenshinen ('Garden of the Heart of Heaven") at the I.M. Pei West Wing, Museum of Fine Arts, Boston, USA, which was completed in 1987 was his most prominent work. Reminiscent of the gardens in the shogun estates of the Edo period (1603-1867), the Tenshinen incorporates symbolic details of the New England landscape (rocky coastline and deep forests) over which Nakane flew in a helicopter when he was formulating his garden plan. The Japanese garden at Jimmy Carter Library and Conference Center in Atlanta, Georgia, was also designed by him.

The Tenshinen was re-opened on April 2015 after a year-long effort to restore the garden, and documented by the Nippon Television Network Corporation. In the course of the renewal, new plants, paving, irrigation, drainage, lighting, and granite gravel were installed.

In Toowoomba, Queensland, Australia, the Ju Raku En is a Japanese garden designed by Nakane with construction starting on 1983 and opened in April 1989. The 4.5 hectare garden is jointly own by University of Southern Queensland and the Toowoomba City Council, and is Australia's largest Japanese garden. It is located at the northern side of the campus.

Sources:
1. Elizabeth Ten Grotenhuis, The Journal of Garden History, pp. 231-232, 30 Apr 2012)
2. Museum of Fine Arts, Boston, http://www.mfa.org/collections/featured-galleries/japanese-garden-tenshin-en

Trees of Our Garden City: A Guide to the Common Trees of Singapore

Publisher: National Parks Board, Singapore
First published: 2001, Second ed: 2009
Authors: Tee Swee Ping et al. (see more below)
Pages: 210 pages
Showcasing 132 trees and 18 palms species

Chapter Headings:
Foreword
Introduction
Chapter 1 - Our Garden City Story
Chapter 2 - Tree and Palm Species
Chapter 3 - Tree Biology
Chapter 4 - Tree Care (Tree Planting, Tree Planting Distance, Tree Inspection, Tree Pruning, Pests and Diseases of Trees, Conservation of Urban Trees)
Chapter 5 - Growing Trees in Rooftop Gardens
Chapter 6 - Trees and the Environment
Glossary
Bibliography
Index (by Botanical names, by Common names, by Chinese names)
Acknowledgements

Editorial Committee:
Tee Swee Ping
Yong Wei Kwong
Ms Jerrie Ng Sy Chi
Ms Germaine Ong Zi Ming

Writers & Contributors:
Dr Chin See Chung, Dr Tan Puay Yok, Dr Benito Tan, Dr Nura binte Abdul Karim, Dr Lim-Ho Chee Len, Dr Lena Chan, Dr Fong Yok King, Ang Chee Wee, Ali Ibrahim, Abdul Hamid bin Mohd, Chan Chun Leong, Derek Chan Yeow Kwang, Low Yong Kwee, Eric Ong Yongquan, Hassan Ibrahim, Ms Kalthom Abdul Latif, Lahiru Suranga Wijedasa, Lee Jia Hwa, Lim Choon Boon, Ms Lily Chen Mei Jun, Lua Hock Keong, Muhamad Shahrizal Sihab, R Mathichandran, Ms Patricia Yap Siew Yen, S K Ganesan, Simon Longman, Sim Eng Koon, Tan Chin Peng, Ms Thereis Choo Yi Siang, Toh Chin Heng, Voon Chin Seng, Ms Lee Pin Pin, Ms Germaine Ong Zi Ming, Ms Mitina Tan, Ms Melanie Wee Mei Choo, Ms Chan Yang Sun, Yong Wei Kwong, Ms Jerrie Ng Sy Chi, Tee Swee Ping.

Photos Credits:
Chan Chun Leong, Lee Jia Hwa, Ms Patricia Yap Siew Yen, Lin Yangchen, Paul Leong, Ms Lily Chen Mei Jun, Choy Heng Wah, Gary Chua Liat Seng, Benjamin Lee Yi-Hann, Mervin Quah, Ms Eleanor Soh, S K Ganesan, Wong Tuan Wah, Dr Yam Tim Ying, Tee Swee Ping.

Tree Conservation Area (TCA)

Tree Conservation Areas have mature trees that enhance the environment with their lush greenery and shade. It was established in Singapore to control careless felling of those trees.

Protected trees are defined as:

• More than 1m girth (or 0.31m diameter)
• Heritage trees and roads (could be outside TCA)
• Within vacant land

Trees could be protected whether on State and privately owned land. They cannot be felled without approval from National Parks Board (NParks).

Failure to do so:

• Compensation (when case taken to court; determined by prosecution. between $76,000 and $50,000 based on past cases) and fine of not more than $50,000, or
• Composition fine of $2,000 for each tree felled [1]

A Certified Arborist report may be needed to accompany the request to NParks.
Depending on tree species, size and condition, a basic assessment report costs $150-$600 per tree.

To check if your land is on TCA and for reports to accompany your submission, contact a Certified Arborist (not from NParks) from this list:
http://www.cuge.com.sg/Listing-of-Certified-Arborists


Reference:
1. http://wildsingaporenews.blogspot.hk/2009/07/house-owner-fined-6000-for-cutting-down.html
2. https://www.nparks.gov.sg/gardens-parks-and-nature/tree-conservation-areas

 TCA 1

TCA 2

Detection Tools for Advanced Tree Assessment (with Prices)

1. Cordless drill with a small-diameter bit (Bosch drill GSR 18V Li-Ion)

USD $300

2. IML-RESI MD300 (including Bosch drill GSR 18V Li-Ion)

USD $1,600

 

3. IML-RESI PD300

USD $7,400

 

4.  Rinntech R650-ED

USD $7,800

5. PiCUS Sonic Tomograph with 10 sensors

USD $20,000

6. Tree Radar Model TRU-900 (without wheel cart)

USD $32,000

A summary of the prices. A higher price does not equate to better detection and charting of tree decay.