Enhancing greenery in the Civic District

As part of our commitment to transform Singapore into a ‘City in a Garden’, the National Parks Board (NParks) has implemented various initiatives to further enhance the greenery and landscaping islandwide.

This includes rejuvenating the landscaping in the Civic District together with the Urban Redevelopment Authority (URA), and bringing back old greenery favourites, leveraging on the deep capabilities, expertise, and technology built up by NParks over the years.

1.   Structural Cells for Stronger Root Growth at Queen Elizabeth Walk

In a highly urbanised environment, there may be limited spaces onsite for planting, especially for older trees that need more rooting space.

To improve NParks’ ability to plant large trees in a highly urbanised area where rooting space is limited, NParks has developed innovative polypropylene structural cells, which are modular suspended pavement systems installed under roads and paved surfaces to allow for greater rooting and breathing space. The structural cells also have the bearing capacity to hold heavy structures.

Structural cells pave the way for a fundamental shift from the current industry norm. Thus far, the industry norm for tree planting was to install a contiguous area of soil to grow trees and sustain loads. The heavy weight of the load on the soil resulted in a highly compacted soil environment impenetrable to tree roots.

With structural cells, the load is sustained by the cell, resulting in an improvement of the soil conditions (i.e. low compacted soil, enhanced drainage, etc.) which are essential to the growth of healthy roots. NParks had started off working with trademark products and thereafter, designed and developed several variants of structural cells of our own to suit a variety of urban, local conditions.

These structural cells are currently being installed for a new row of trees along Queen Elizabeth Walk as part of the Jubilee Walk. The structure cells will help ensure that the trees continue to thrive in an urban environment, even when they are old. As a result of this, we will see a row of beautiful native Kayu Arang (Cratoxylum cochinchinense) trees, characterised by their weeping crowns, distinctive bark and crimson flowers.

Fig 1. Variety of cells designed & developed by NParks

Installation of structural cells along Queen Elizabeth Walk

Kayu Arang (Cratoxylum cochinchinense) with its weeping crowns, distinctive bark and crimson flowers

2.   Reinstating the growth of five Angsana Trees to Esplanade Park

Between 1960s to 1980s, a popular meeting place for couples was an area under the shade of five Angsana trees at Esplanade Park. Commonly known as “gor zhang chiu kar” in Hokkien, all five trees had to be removed in the 1990s, as a fungal disease called the Fusarium wilt killed off many mature Angsana trees.

To bring back memories of a once popular landmark, NParks and URA will be transplanting five mature Angsana trees in October 2015 to where the original trees were.

These Angsana trees are no longer affected by the wilt disease due to the research and field trials done by NParks in the mid-1990s where Angsana seeds and cuttings were collected from tropical regions of the world.

The research team was screening the seedlings for wilt disease resistance. 115 seedlings survived the final screening in the nursery. In 1997, these 115 resistant saplings were planted on several roadside verges known to have history of the wilt disease infection. Till today, all the saplings are still in existence, and have grown into mature trees and are still free of the disease.

3.   Ensuring the health of existing mature trees

NParks has a more comprehensive programme to rejuvenate existing mature old trees in the Civic District.  In addition to pruning, biostimulants, which contain various micronutrients, humic acids and organic compounds, were applied to the trees.

These biostimulants help to improve soil structure, encourage rooting and release nutrients to the tree over an extended period of time. Trees in Esplanade Park and Empress Place have responded positively by looking healthier and putting out new shoots.

NParks also experiments with new mixtures of fertilisers to improve the health and vigour of trees. Organic fertilisers, such as processed chicken dung with lactobacillus, were tested and proved to be effective in rejuvenating trees. NParks will begin using these organic fertilisers for the trees in the Civic District from mid-May 2015 onwards.

Yellow Flame trees along Queen Elizabeth Walk

Angsana along Collyer Quay

Rain Trees along Connaught Drive

4.   Tree Transplanting outside Asian Civilisation Museum

As part of the enhancement of the Civic District, URA and NParks will be creating more landscaped open spaces, for both informal and organised events. Eight mature rain trees, each about 40 years old, with the largest one weighing more than 90 tons each, have been successfully transplanted from their previous location into the new lawn in front of the Victoria Theatre and Concert Hall.

Prior to the transplanting, advanced preparations were made up to two weeks before to ensure that the trees would be ready for their “home-moving”. For two days, the ground around the trees was excavated and the trees were inspected by a trained arborist to ensure that they were healthy, growing vigorously and free of decay, rot and diseases. The trees were also pruned to minimise stress from the loss of water.

For mature trees which are to be moved to a nearby location, the best method to employ is the “raft method”. Twenty-three 168mm diameter steel pipes were driven under the trees in a contiguous manner to create a 6m x 6m raft for the root ball. This process took four to five days

A lifting frame, comprising four 450 x 250mm steel rectangular sections, was placed under the raft. The lifting straps of the crawler crane were then attached to this lifting frame.  A root ball guying frame, together with vertical planking, was installed to secure the root ball to the lifting frame. For this method, the tree is transported vertically, with a crawler crane employed to lift and move the tree to the new location. A 600-ton crawler crane with a super-lift was brought in to lift the trees.

Rain tree being transplanted in the Civic District

To ensure stability, all eight rain trees have been physically anchored to the ground by securing the root ball with buried concrete blocks that act as anchors. Each tree took about two weeks to transplant.  All eight trees are in good health.

Artist’s impression of the lawn when completed

5.   Reintroduction of greenery favourites

There are also plans to re-introduce old favourites and relatives such as the Mussaenda “Queen Sirikit”, Gardenias (Gardenia mutabilis), Frangipani “Singapore White” (Plumeria obtusa “Singapore White”), Dwarf Frangipani “Singapore Pink” (Plumeria obtusa “Dwarf Singapore Pink”), Singapore Kopsia (Kopsia singapurensis), Penang Sloe (Kopsia arborea) and Pink Kopsia (Kopsia fruticosa) Ylang Ylang (Cananga odorata) and Ming Aralia (Polycias fruticosa) to the Esplanade Park area to bring back a sense of nostalgia to one of the oldest parks in Singapore.  

Epiphytes such as the Pigeon Orchids (Dendrobium crumenatum), Staghorn ferns (Platycerium coronarium), Cymbidium finlaysonianum, Coelogyne rochussennii, Dendrobium aloifolium and Bulbophyllum medusae will also be planted on trees to provide volume, colour and interest to the landscape.

Mussaenda “Queen Sirikit”

Pigeon Orchids (Dendrobium crumenatum)

Other initiatives to rejuvenate the Civic District include planting the Frangipani “Singapore White” in the newly created planting beds at Raffles Landing along the Singapore River Promenade. The Frangipani “Singapore White” was specially chosen to complement the white Stamford Raffles statue standing on site to give the area a sense of stateliness.

Frangipani “Singapore White” (Plumeria obtusa “Singapore White”)

These greenery enhancement initiatives are part of the Civic District refurbishment works. The public can enjoy these enhancements in the coming months.

Fig 3. Timeframe of Civic District enhancement works

6.   Planting of Royal Palms outside the National Gallery

The row of Royal Palms outside the National Gallery Singapore (former City Hall) had been an iconic landscape feature along St Andrews Road, framing the stately colonial building and had witnessed many important events at steps of the former City Hall and The Padang. 

The palms were removed in 2011 during the transformation of the former City Hall into the National Gallery Singapore. However, upon completion of the project, a row of mature royal palms were planted to replace the palms in October 2014 and March 2015, thus restoring the iconic landscape feature.

7.   Visual links