The art and science of urban forestry

June 9, 2024

Indigenous trees such as the Banyan, Arjun and Jamun significantly reduce the temperature and clean the air

The art and science of urban forestry


here is hidden wisdom in nature. There is a balance, a scheme of things, upsetting which can have catastrophic consequences. Take, for instance, indigenous trees, how they have adapted, over generations, to thrive in this region and the role they play in sustaining the ecosystem and the climate. Unfortunately, in Faisalabad, this is being overlooked. Native trees are being fast replaced by exotic species that ‘look good,’ resulting in a decline in their population. This change has severe consequences for the climate and public health.

Residents now face extreme heat in the summers and dense smog in the winters. During the current summer, Faisalabad endured temperatures hovering around 47 degrees Celsius for three weeks, highlighting the urgent need for effective tree plantation.

Although the awareness of the importance of planting trees has increased among the citizens, government-led plantation efforts often fall short. These initiatives are frequently limited to ceremonial events, failing to substantially enhance the city’s green cover. Furthermore, there have been allegations that government departments favour planting expensive exotic species.

To combat these issues, there must be a renewed focus on planting native trees, which are better suited to the local environment and more effective in mitigating extreme weather conditions. This approach will not only improve climate resilience but also safeguard public health.

It is important to note that the National Forest Policy 2021 mandates that at least 25 per cent of urban areas should be covered by forests or greenery. The international standard for urban green cover is even higher [40 per cent]. According to the Master Plan of the Faisalabad Development Authority, the city’s green cover is below 2 per cent.

Data obtained under the Punjab Transparency and Right to Information Act 2013 reveals that the Environment Department, with support from industry, has planted 184,000 saplings over the last five years. A similar request for information from the Parks and Horticulture Authority Faisalabad has elicited no response. An appeal against this lack of transparency is currently pending with the Punjab Information Commission.

Information from the Forest Department, also obtained through the Right to Information Act, highlights a troubling trend. Over the last five years, annual plantation along canals and in government forests in the Faisalabad Forest Division has decreased by more than 50 per cent.

These figures underscore the urgent need for effective and transparent urban forestry initiatives to meet both national and international standards for green cover. Strengthening these efforts is essential for improving the city’s environmental health and resilience against climate challenges.

According to Dr Fahad Rasheed, an associate professor in the Department of Forestry and Range Management at the University of Agriculture, Faisalabad, urban tree planting by parks and horticulture authorities primarily focuses on aesthetics. “Tree species are chosen based on their appearance, with no thought for selecting trees or plant species that effectively clean the environment,” he says.

Dr Rasheed points out that the Forest Department opts for species that are more likely to survive rather than those proven to reduce environmental pollution. “They often plant conocarpus and eucalyptus because these trees are hardy. However, their long-term environmental benefits are minimal and their drawbacks significant,” he says.

“Tree species are chosen based on their appearance, with no criteria for selecting trees or plant species that effectively clean the environment.”

The professor says native trees have a natural ability to cope with environmental changes and pollution, making them a better choice for urban areas. “Given the increasing focus on air quality due to climate change and rising pollution, it is crucial to engage both horticulturists and foresters in the Parks and Horticulture Authorities to ensure the selection of tree species that are compatible with urban environments,” Dr Rasheed suggests.

Dr Rasheed’s research, supported by America’s Tree Fund, evaluated ten tree species: mulberry, semal, sheesham, peepal, conocarpus, eucalyptus, alstonia, arjun, banyan and jamun.

“According to our research, the banyan tree is most effective at reducing temperature extremes and air pollution. The arjun tree ranks second and the jamun third. These trees should be planted extensively in urban areas,” he says.

The research ranks alstonia as the fourth most effective tree, followed by peepal (fifth), eucalyptus (sixth), sheesham (seventh), conocarpus (eighth), semal (ninth) and mulberry (tenth). Dr Rasheed’s findings highlight the importance of prioritising native species for urban tree planting to maximise environmental benefits.

He says that the texture and structure of tree leaves vary significantly, making some species more effective at trapping particles that cause environmental changes and air pollution. For his research project, leaves from ten tree species were collected from three locations: central Faisalabad, city’s suburbs and rural areas.

The sampling process was meticulously repeated. The first sampling occurred 128 days after heavy rainfall. The second and the third samplings were held thirty days after rainfall. “Leaves were collected from each tree at a height of ten metres to account for variations in leaf size,” Dr Rasheed says. “Larger leaves naturally capture more particles.”

To maintain consistency, a square metre of leaves from each tree was sampled. These leaves were then cleaned to remove the contamination particles. The concentrations of PM10 and PM2.5 particles were collected from the leaves and analysed. “This ensured that we could accurately measure and compare the effectiveness of each tree species in trapping pollution particles,” says Rasheed.

Dr Rasheed’s findings underscore the importance of selecting tree species based on their environmental benefits rather than their aesthetic appeal. His research provides valuable insights for urban planners and environmentalists aiming to improve air quality and combat climate change through strategic tree planting.

Dr Fahad Rasheed says that the first part of his research project focused on analysing how effectively tree leaves collect pollutants from the environment. In the second part, the study examined the reduction of pollutants on the surface of each tree’s leaves after rainfall. “These parameters helped determine how well tree leaves clear existing pollutants post-rain, which indicates their overall effectiveness,” he says.

Interestingly, the tree species most effective at controlling particulate matter were not as efficient at cleaning those particles off their leaves after rainfall. “Although these trees were not very effective in shedding pollutants during rain, their ability to remove pollutants from the atmosphere was so significant that they are still a better choice for urban plantation than other species,” Dr Rasheed says.

Stressing the importance of planting native trees, which have a natural ability to adapt to environmental changes and pollution, he says, “In the next phase of this project, I plan to collaborate with the Parks and Horticulture Authority and the Forest Department to establish nurseries for these native trees. By planting more of these trees in urban areas, we can significantly mitigate the severity of climate change and air pollution.”

The writer has been associated with journalism for the past decade. He tweets@ naeemahmad876

The art and science of urban forestry