After Typhoon Yagi, a multitude of trees in Hanoi were uprooted and damaged. Architects pointed out the reasons why urban trees in Hanoi are prone to uprooting and suggested that the capital should change its tree planting methods on the streets.
The passing of Typhoon Yagi through Hanoi caused many trees to be uprooted and fall. According to a quick report from Hanoi, as of 7 PM on September 7, 2,455 trees had fallen, and 273 branches were broken.
Large trees fell onto homes, buildings, and property; resulting in one fatality, six motorcycles, and thirteen cars being damaged due to the storm.
Trees uprooted in Hanoi after Typhoon Yagi.
Regarding the numerous trees that fell in the urban districts of Hanoi after Typhoon Yagi, architect Trần Huy Ánh (Standing Member of the Hanoi Architects Association) stated: “We can all see that the trees in Hanoi were uprooted and fell after Typhoon Yagi due to their very shallow root systems. The reason is that the roots are very shallow, the soil has become loose, and the concrete sidewalks restrict water from reaching deeper layers, leaving only surface water. Naturally, shallow roots will cause trees to fall quickly.”
“What I have shared is something that everyone can observe, yet the urban management and green tree agencies have made almost no changes, continuing with the old methods of planting trees by merely digging a hole over 1 meter deep and then planting the trees.” – Architect Trần Huy Ánh remarked.
He further elaborated on urban tree planting, saying: “With the current planting methods, if the trees are small, they will not allow high-rise buildings to develop properly. If we plant larger trees, they may be strong and stable but will still require a threshold to spread into the shallow layer, which can create new dangers.”
“Many mahogany trees and other large trees on the streets have high weight loads. During Typhoon Yagi, we saw trees behaving like large ‘sails.’ The wood swaying in the wind, combined with shallow roots and high weight, made it easy for trees to fall and pose a danger to structures or anything beneath them.”
Uprooted trees causing damage to residents’ property after Typhoon Yagi.
In addition to suggesting changes in tree planting methods in urban areas like Hanoi, Architect Trần Huy Ánh noted: “Over the past decade, our tree planting strategy has not changed at all. I have sought ways to plant new trees, by utilizing discarded utility pole bases to ’embed’ the roots into them. The result after the recent major storm was that the trees remained very stable, only shedding leaves due to the wind.”
“This is also a technique that modern cities around the world have already adopted, using deep stakes and perforated tubes for trees to grow inside, allowing the roots to grip firmly and spread out horizontally, ensuring stability. This way, trees can adapt to various conditions, including drought. These are the strategic suggestions for urban tree planting that we need to change.”
Why are street trees easily uprooted, while forest trees are not? Natural trees grow from seeds eaten by birds, which are then deposited in the soil by wind and rain, allowing them to sprout. A tree that reaches 50 meters tall will have deep roots extending similarly down into the ground, with roots spreading out around it. The roots of different trees intertwine underground, helping to secure them. This is the most important reason that makes it difficult for strong winds during storms to uproot forest trees. The foundation of trees in the forest is extremely solid due to their root systems. The second reason is that trees in the forest provide mutual shelter for each other, allowing wind to pass through lightly, minimizing impact except for shedding leaves during severe conditions. The third reason is that forest trees are not encroached upon by humans, which can damage their root systems… In contrast, street trees are grown in nurseries, and when they reach several meters to a few dozen meters, their roots are cut off (the essential roots for stability against storm winds) before being transported and planted in holes. After some time, a tree can grow to 50 meters tall, but its roots only spread between 3-5 meters without any taproots. A solid foundation (comprising both taproots and fibrous roots), mutual shelter (a cluster of trees), and safety from human encroachment (such as concrete paving and excavation) are the three reasons that make uprooting forest trees difficult, regardless of the strength of the storm. Conversely, street trees are easily uprooted even in light winds, as they lack all three protective factors found in forest trees. |
