Urban infrastructure explosion causing loss of trees

Studies from many megacities across the world show that trees in heavily urbanized areas promote sustainable behaviour such as walking and cycling, in turn promoting improved mental and physical health, as highlighted by a Mongabay-India (MI) report. Trees in metropolitan cities are a cost-effective solution to combat the effects of urban heat islands and mitigate floodwaters. It is estimated that urban trees could save up to $500 million annually in public health, storm water management and climate mitigation, according to a report published in Ecological Modelling journal as quoted by the MI article. Highlighting another recent study of street trees in Kochi, Kerala, and Panjim, Goa, the MI article points out that it reported low density of roadside trees and a decline in tree cover in recent years. This study published in the Journal of Urban Ecology, assessed the street tree communities in the rapidly changing cities of Kochi, Kerala, and Panjim, Goa, along with public perceptions of their services.

The abstract of the study states that although 41% of the global urban population lives in smaller cities, the nature and trajectories of urban nature, ecosystem services and human-nature connections in smaller centres is relatively unknown. While megacities in developed countries move towards biophilic urban planning and participatory decision making, basic information on tree communities and their perceived services is a bottleneck in achieving these goals in such small urban centres. In its Introduction, the study says that urban street trees and greenery are important and effective solutions to improve sustainability and resilience of cities as well as the well-being of residents. Trees contribute directly to biodiversity conservation and provide critical patch connectivity for plants and animals. Further, urban trees reduce pollution, contribute to climate resilience by mitigating stormwater and reducing urban heat island effects as well as improve physical and mental health of residents.

Moreover, urban trees could save megacities nearly $500 million annually. Recognizing the value of biophilic cities, urban planning in major cities is shifting towards regreening and rewilding. Street trees could be a low-cost tool in creating sustainable cities in developing countries, although other solutions (e.g., green roofs) are gaining popularity in the developed world. Efforts at protecting street trees and urban habitats make significantly high contributions to five United Nations Sustainable Development Goals, namely zero hunger, good health and well-being, clean water and sanitation, sustainable cities and communities and climate.

Contrary to possible assumptions of a decrease in tree density with an increase in population density and urbanization, researchers of the study observed lower abundance of street trees in these smaller urban centres in comparison with metropolises like Bengaluru. Moreover, people reported ongoing declines in tree cover in both cities studied because of infrastructure expansion. Given the anticipated explosive growth of urban infrastructure in smaller cities across the global South, it is likely that these and other such cities will experience a further decline in urban tree cover in future decades – unless action is taken now. At the same time, researchers found that residents report strong social and cultural connections to trees around them. They were more likely to value cultural and regulating services of trees, compared to direct benefits like food, fuelwood and medicine, which may have greater value in villages.

In its conclusions, inferences from the study point to the fact that smaller urban centres could be socially and ecologically distinct from metropolises, necessitating interdisciplinary inquiry and action. India currently has 8 metropolises, but over 200 smaller urban centres, where we know little about growth and urban sustainability. Out of these, the growth of 100 cities is funded under the National Smart Cities Mission aimed at driving economic growth and quality of life. For the socio-ecological resilience of these urban centres, biophilic planning needs to keep pace with projected rapid economic and infrastructural growth. Developing a better understanding of factors such as the distribution of urban trees in smaller urban centres, changes over time, main threats to their survival, and perceived ecosystem services and disservices of urban trees, through studies like this, can help policy makers, planners and community groups develop a deeper engagement with urban ecological protection and restoration.