Urban trees have a significant impact on controlling air pollution, can reduce city temperatures

trees

By Kanchi Kohli and Manju Menon*

Across India, residents’ mobilisation in cities to save trees has gained unprecedented momentum. The felling of 22,000 trees for the construction of an airport in Goa, over 14,000 for a world trade centre and government housing in Delhi, and another 1,800 for a metro car shed in Mumbai has seen urban dwellers take to the streets, petition government authorities and fight it out in court. Recently, Bengaluru residents successfully stopped the felling of over 2,000 trees for the construction of a steel flyover in the city.

Most city officials view trees as being “in the way” of traffic, sunlight, housing, commercial and transport infrastructure. Yet every city has tree lovers who make time from their quotidian life to plant them, nurture them and share their shade, beauty and fruits with the general public. Today they are stepping up to protect natural heritage and resist the systematic dismantling of green spaces that are carried out in their name by urban governments. They are having to learn and educate their officials about the relationship between urban trees and the city’s numerous problems.

Understanding urban trees

While forest areas have been well established as a place of culture, livelihoods and ecology, city trees are only coming into attention through more scholarly and popular writing about them. Neha Sinha, a wildlife conservationist, calls trees an “urban coordinate” as they help residents identify with a particular part of the city. Within a few hours of a bird survey, she spotted nearly 26 bird species in Delhi’s Sarojini Nagar. Another survey just a year before had recorded 60 species in the same area where almost 11,000 trees would have been felled, had it not been for tree-loving Delhiites.

An empirical study by Harini Nagendra who teaches at Azim Premji University points out that trees help to reduce heat in cities. According to her 2013 paper, trees reduced surrounding air temperatures by as much as 5.6°C and cooled off tava hot road surface temperatures by 27.5°C. The paper also shows that trees mitigate the impact of dust pollution caused by construction activities. The paper highlights that street trees have a significant impact on controlling air pollution in cities like Bengaluru as they reduce Suspended Particulate Matter (SPM) levels by as much as 75 per cent on roads.

Laws not for large scale felling

Recent years have seen a massive rise in urban tree felling because of reconstruction, real estate development and growth of cities. The Tree Acts governing the preservation of trees outside officially recorded forest areas in various states like Goa or Delhi were not set up to tackle large-scale tree felling. Their objectives of proactive tree preservation were to be met by the task of regular tree census and the setting up of an interdepartmental tree authority.

A closer look at forms attached with these laws reveal that tree felling clauses were responding to instances where private individuals approached a single officer in the forest department to cut trees on the property they owned or occupied. Today real estate companies, road contractors and government departments use these laws to get approvals for large-scale projects that involve en masse tree felling.

None of this involves any prior information to residents. Citizens also struggle to use the legal scrutiny provisions under these laws to check if due diligence is done before permissions are granted. As is evident with the recent proposals for redevelopment in Delhi, the Tree Authority, which has oversight function under these laws, may never review project impacts. Maharashtra’s 2017 Tree Act amendment was challenged in the High Court as it allowed the Municipal Commissioner to act as the Tree Authority in some cases, creating conflict of interest. During the period when the Pune Tree Authority had a member of Kalpavriksh, an NGO that mobilised citizens through information sharing, the Authority faced a huge backlash from construction lobbies.

When brought under pressure by citizens, governments go into high-gear planting drives, transplanting and compensatory plantation and courts ban tree felling, a move that can be unpopular with some residents. Both these approaches can bring their own challenges and can even be counter-productive.

Trees in urban planning

With many Indian cities like Kanpur, Varanasi and Raipur rising to the top of the global pollution map along with Delhi, its time clean air plans also factored in the protection of urban trees. Governments have been focused on the technological remedies to the pollution crisis but it is equally important to grasp the ecological solutions to them too. Citizens’ campaigns in Mumbai, Delhi, Bengaluru and other cities are pushing their governments to bring together the questions of urban infrastructure, ecology and governance. This approach can help demonstrate models for truly sustainable and inclusive cities.


This article was first appeared in DNA


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