Local Climate Action: Preserving City Greenery in Colombo
By: Just My Nature
Tags: City Planning, Colombo, Sri Lanka, Urban Planning, Climate Change

Anna Singankutti, Guest Columnist*

Ancient trees are being cut down in cities like Kandy and Colombo. Just last month in Colombo, a decades old Banyan fig tree, was cut down in front of the Asiri surgical hospital. The Colombo Municipal Council (CMC) issued a permit for the Urban Development Authority (UDA) to cut down the tree. The UDA’s project consists of making a 4-lane road towards Nawala Road in order to decrease traffic on the Kirimandala Mawatha. The tree, according to the UDA, was taking up too much space and did not meet the street lining requirement for the project . To balance the felling of the tree, the CMC will be planting 15 sapling trees. The story of the Banyan tree being cut down by the UDA is another instance where development projects are being prioritized over preserving nature.

Deep rooted trees. Picture courtesy of Patricia Mamelka.

Benefits of greening: Many trees together in one area form a forest; unfortunately, due to urbanization, the cities we occupy now, only have the remnants of forests that used to sprawl across the area. When we look closely though, greenery always tries to make its way back through the cracks and crevices. Colombo, Galle and Kandy still have pockets of greenery.

There are city parks and plants that sprawl the sides of buildings and bridges, as well as the trees that have been allowed to stay in their native home that now straddle busy roadsides.

However, the overcrowded, fast developing city scape is not a nice home for greenery. Trees and plants continue to be destroyed to make space for our human habitations. We forget the ecological services that trees and deep-rooted plants offer: they prevent soil erosion, regulate the water table, store carbon and act as a wildlife habitat. Without city greenery, we have increased the effects of floods and droughts, loss of ground water quality, a poorer air quality and less biodiversity .

Urban heat island effect: One of the grave effects of losing city greenery is increased temperatures in the city. There is a specific term for this phenomenon called the “urban heat island effect” (UHI). Pulse.lk covers this topic excellently, explaining that the UHI is defined as the difference between city temperature with the temperature of surrounding rural areas due to human activity.

We all can feel the stark difference between walking on a paved road in the city on a hot day and feeling the unbearable heat radiating upwards at our face and not just down from the sun. Whilst, in rural areas, a hot day is a bit more bearable due to the higher tree coverage which provides well needed shade. The difference between the city and suburb temperature is found to be up to 5.5 degrees celsius! The drainage systems in cities trap water under asphalt roads, it sits in sewers and cannot evaporate easily. Whereas in rural areas, water drains easily through the topsoil and is transpirated by vegetation. The higher evapotranspiration processes of the suburbs allow the cooling effect.

The UHI effects are exacerbated even more by using air conditioning and driving cars. For instance, people stay inside and turn on their ventilators or take a taxi instead of walking when it’s too warm, but this generates more heat in the environment.

W hy should we care about the Urban Heat Island Effect?

It increases the effects of climate change: energy consumption goes up during hot days resulting in increased air pollution and greenhouse gas emissions. The Federation of Environmental Organizations (FOE) says that the “correct placement of trees around buildings can reduce the need for air conditioning by 30% thus reducing the consumption of electricity”.

It has impacts on human health: as UHI’s temperatures are higher during the daytime, there is less night time cooling and more air pollution. This is the perfect recipe for increased heat-related deaths and illnesses! People with respiratory difficulties and those prone to heat cramps, exhaustion and heat strokes are more at risk. This often includes the elderly and very young children and those with existing medical conditions.

It is destroying existing urban greenery: extreme temperatures damage some tree species. The higher ambient temperatures and the low soil moisture result in the scorching of foliage and the bark of trees. Saplings are very vulnerable and even established trees can die due to this phenomenon. This is unfortunately already happening along congested roads in all the major urban areas.

City greening: The combination of ancient trees being chopped down in urban areas as well as the threat of UHI effects means that locals have to take action to make their cities green or at least preserve the green that is left. As smaller towns develop into larger towns and then into cities, the UHI effects will only increase. It is vital that we all have a mission: increasing the overall vegetation within city boundaries .

This can be as simple as starting your own initiative to buy tree saplings and planting them along roads and sidewalks, car parks etc. It is essential though to collaborate with someone who has knowledge on local tree species and to choose saplings with a higher heat resistance. You can get involved with other environmental and activist groups and find ways to cooperate with your city districts and learn about funding for projects and volunteering. Sign petitions to save crucial Banyan and Bodhi trees. There is a program launched by the Federation of Environmental Organizations Sri Lanka (FOE) for greening the city of Colombo, to create a healthy and viable environment for everyone to live in.

Lastly, city planning in Sri Lanka should seek to incorporate more green spaces, such as parks, canopy covered roads and forest pockets. Don’t forget that as an individual you can always make the decision to use more energy efficient appliances inside your home. When planting saplings, it is also important to remember it takes up to 20 years for it to grow to a size where it helps to mitigate climate change, therefore, the maintenance of trees and community awareness is also vital. Hence, let’s make this massive goal a reality, by smaller, yet practical steps such as involving our friends and neighbours in the discussion and taking them along in this eco-friendly journey.

Sources:

http://www.themorning.lk/greening-the-city-of-colombo/?fbclid=IwAR3rApxqxnX_b_pndisMeCePNnLbWCMZQRK_3uJQ9Up6750O8UontTzeMX4

https://www.facebook.com/feosrilanka/photos/a.607788709244105/3631304146892531/

TESKEY, R., WERTIN, T., BAUWERAERTS, I., AMEYE, M., MCGUIRE, M.A. and STEPPE, K. (2015), Tree response to extreme heat. Plant Cell Environ, 38: 1699–1712. https://doi-org.proxy.library.uu.nl/10.1111/pce.12417

Heaviside, C., Macintyre, H. & Vardoulakis, S. The Urban Heat Island: Implications for Health in a Changing Environment. Curr Envir Health Rpt 4, 296–305 (2017). https://doi-org.proxy.library.uu.nl/10.1007/s40572-017-0150-3

Wang, Y., Li, Y., Sabatino, S. Di, Martilli, A., & Chan, P. W. (2018). Effects of anthropogenic heat due to air-conditioning systems on an extreme high temperature event in Hong Kong. Environmental Research Letters, 13(3), 34015. https://doi.org/10.1088/1748-9326/aaa848