Green Cities: The Strategic Value of Trees in Urban Spaces

Nairobi, our beloved capital city, was often referred to as “The Garden City.”  Despite its industrial beginnings, Nairobi was developed with the idea that nature and urban development could coexist in harmony. Historically, the city planners laid out wide streets with abundant trees and large parks were set aside for the collective enjoyment of all. Their foresight earned the city its nickname. James Gichuru road, among many other roads used to be breathtaking with the purple haze of jacaranda trees in flower. The charm of tree-lined streets, road-side nurseries with plants and multi-coloured flowers and pots, sprawling bougainvillea and cherished forests and green spaces have delighted both residents and visitors for many years. Our city is unique, it offers beauty amidst the hustle and bustle and the unique opportunity to see wildlife, trek through forests and enjoy time with family and friends in nature. This harmony with nature has always set Nairobi apart from other global urban centres.  This heritage has long been taken from granted. However, as the city continues to grow, the need for integrating trees into urban planning becomes more urgent. Concrete jungles often suffer from poor air quality, excessive heat and the loss of access to nature can have adverse effects on city dwellers.

Improving Air Quality

We are witnessing the devastating effects of poor air quality on health and the daily life of residents around the world. One of the most critical functions of trees in urban spaces is their ability to improve air quality. Trees absorb carbon dioxide and release oxygen through the process of photosynthesis, which helps reduce some of the pollution caused by vehicles and industrial activities. Additionally, trees filter pollutants like nitrogen oxides, ammonia, and sulphur dioxide by trapping them on their leaves, preventing them from entering the atmosphere. By improving air quality, trees help reduce the incidence of respiratory illnesses such as asthma and bronchitis. Cleaner air, free from excessive pollutants, leads to healthier communities, especially in urban areas where pollution levels are typically higher. Studies have shown that cities with more greenery tend to have lower levels of particulate matter, making the air cleaner and healthier to breathe.

The Urban Heat Island Effect

Nairobi residents are sighing with relief today as the rain pours down after a period of excessive heat. Urban heat islands (UHI) are areas within cities that experience significantly higher temperatures than their rural surroundings due to the prevalence of concrete, asphalt, and other heat-absorbing materials. This leads to greater health risks for vulnerable populations.

Trees provide natural shade and cool the environment. A process called transpiration, where water evaporates from the leaves, lowers surrounding temperatures. By planting more trees in urban areas, cities can counteract the UHI effect, making them more comfortable to live in, particularly during hot summer months.

Urban trees can also play a crucial role in water management by absorbing rainwater and reducing the strain on drainage systems. Trees are important for managing runoff. Their leafy canopies provide surface area where the rainwater lands and evaporates. Additionally, their roots take up water and create soil conditions that promote infiltration. This can help prevent costly flood damage and improve the efficiency of municipal water systems. Trees help prevent erosion by stabilizing soil with their roots, reducing the risk of landslides

Urbanization, infrastructure development, and population growth are putting pressure on existing green spaces, with some areas being cleared to make way for new developments and roads. The threat of pollution and climate change is becoming a reality. Increased awareness of environmental issues, stronger environmental policies, and community-driven initiatives are critical to promoting sustainable development.

Psychological and physical benefits

A walk in nature can help reduce stress, anxiety and depression. Many Nairobi residents spend their weekends hiking. Many families cannot imagine not having a place like Karura Forest for the whole family to enjoy.

Resting under the shade of a tree is now becoming a luxury in some areas. Studies have shown that the sight of greenery has been linked to positive cognitive effects. Overall, trees are essential for maintaining a balanced and healthy environment for both humans and animals.

Biodiversity and Habitat Creation

The chorus of birdsong at dawn and dusk in Nairobi has always delighted me. Sadly, there are now fewer trees for these birds to nest in urban areas. Urbanization can lead to the fragmentation of natural habitats. Trees in cities bridge the gap between natural ecosystems and urban development. They provide essential habitats for birds, insects, and small mammals, supporting urban biodiversity. By incorporating a variety of tree species in urban areas, cities can create microhabitats that cater for local wildlife to promote ecological balance.

Conclusion

As the city continues to grow and face the challenges of climate change, the role of trees in creating a sustainable urban environment will become even more critical. Laws may need to be enforced to protect trees from removal. By investing in combating the decline of trees in urban areas, engaging in urban greening initiatives, city planners and policymakers can ensure that trees continue to thrive. Organizations can also play important roles by raising awareness and incorporating tree planting into their CSR activities. In conclusion, the importance of trees in urban spaces cannot be overstated, protecting our city’s green heritage is vital for our well-being.

Article de Shailja Sharma, membre du corps enseignant du SBS et coach en leadership et en carrière