Does Singapore still have a place for big trees?

Recently a massive tree fell onto one of Kuala Lumpur's busy streets. One was killed, and traffic was stalled for hours while help arrived to rescue those stuck in their cars.

Singapore has had similar incidents of fallen trees that have destroyed infrastructure, or ended lives. A tembusu tree fell and killed a mother in Singapore Botanical gardens in 2017. A lady was killed in 2022 when a tree fell on her while she was jogging. There was another case where a tree fell on an expressway and injured one person in their vehicle.

Why does Singapore have so many trees? Contrary to common belief, the hundreds and thousands of trees Singapore now has are largely due to Lee Kuan Yew's Tree planting initiatives. In other words, most of the forest that exists today is human planted. This was done in the name of improving shade and greenery for the benefit of all Singaporeans, and to turn Singapore into a "Garden city". At the time, little was thought of, or understood about how well trees would require maintenance throughout its very long lives.

Over 2 million trees have been planted, contributing to the lush greenery that defines Singapore today. But now many trees in Singapore are 30-40 years old, and initiatives are still ongoing to increase the number of trees living in Singapore. The latest one being the One million trees by 2030 initiative.

In addition, you may notice that the trees in new developments today, or near the latest expressways, are no longer the grand, heritage species that was once heavily encouraged more than 50 years ago. And that's because we've learnt a lot more about the cost of having big trees:

The cost of having big trees

• Fertilizing trees - Urban soil is usually less nutritious, less biologically active than those in natural reserves. As a result, fertilizing trees is done regularly to support healthy growth of these trees.
• Pruning branches - You may often find teams of arborists in their trucks and vans going around roadsides and highways during off-peak hours. They help to cut off branches to direct the growth of a tree; a lopsided tree is more vulnerable to getting toppled during heavy storms.
  
• Monitoring for sickness - Lots of manual work is done by arborists and "tree doctors" who go around checking trees for pests, root rot, diseases, etc. Technologies like LIDAR and Geographic Information Systems (GIS) help to speed up the work, but these are heavy investments in their own right.
  
• Building support for older trees - Sometimes, metal and wooden braces are built to help trees that are at risk of falling, or breaking branches.
• Land space - Arguably the biggest cost of all: committing to grow a big tree somewhere, usually means a sizable area that cannot be used to build infrastructure, both horizontally and vertically.

The advantages of having big trees

• A big tree can itself be a whole ecosystem, from its roots to its top-most branches. Certain fungi species have a symbiotic relationship with the trees' roots. Branches the of trees serve as homes for hundreds of species of climbers and creepers. These in turn also create spaces for birds, small mammals and insects to roost. The fruit, flower, seeds, and even sap are used as food. Small trees can do this as well, but every big tree supports a larger, and more diverse number of species.

• Shade and ambient cooling from respiration. This results in cooler ambient temperatures, and a tree's shade is particularly felt when planted on roadsides.

• Improved Air Quality. Though this applies to almost all trees, big trees have a higher capacity to filter pollutants and produce oxygen, enhancing air quality.
• Soil and Water Conservation: Big trees play a vital role in soil conservation and water management, reducing erosion and filtering runoff. The more complex its root systems, the better and wider of an area is protected. This is particularly important for a city like Singapore where it rains more than half of the days in the year, and flash floods are particularly common.
  

What are we planting instead of big trees now?

Most new developments now feature smaller tree species. Or sometimes landscapers just stick to small palms or bushes instead. Smaller trees that don't grow tall or wide, do not need much space, can be planted in narrow sidewalks. Often times these species' roots also go downwards rather than sideways, which results in less damage to surrounding infrastructure. They often do not need big cranes to saw off extensive branches.

At the same time, they provide less shelter and play a much smaller role to the rest of the ecosystem.

So do we still have space for big trees?

Ultimately, the big trees are best conserved in nature reserves and parks. If a tree falls in these places, humans and infrastructure are less likely to be impacted. Plus, trees survive much more successfully close to each other instead of in isolation. So if we can support efforts to preserve or even grow these spaces in a practical manner, this will ensure we continue to have space for our big trees.

If you happen to have a landed property that has space for a tree, please consider planting one. Or if you are looking to renovate your property and it contains big trees, please consider options to conserve the tree during its renovation.

Maybe in the future, we will innovate more realistic ways to grow bigger trees on top of the vertical skylines of Singapore, and then space will be much less of a restriction. But we are very far from that reality today, as supporting even small-medium size trees on skyscrapers drastically increases the material and maintenance cost to support their size and soil needs.

Singapore is too small for an upstate. This tiny island is all we have, so we have to be creative and conscious with how we stay connected our old, grand heritage trees.