Development without the savaging of urban biodiversity

The Hindu

21-05-2025

Biodiversity, which refers to the variety and the variability of living organisms on this earth — and fundamental to human well-being, a healthy planet, and economic prosperity for all— is under peril. About 25% of species are facing the threat of extinction.
The theme for International Day for Biological Diversity this year (observed annually on May 22) is 'Harmony with nature and sustainable development'. The date 'commemorates the adoption of the text of the Convention on Biological Diversity (CBD) on May 22, 1992'. The Kunming-Montreal Global Biodiversity Framework (GBF) was also developed by the CBD with four goals as well as 23 targets to conserve global biodiversity (conserve and manage 30% of terrestrial and marine biodiversity) by 2030. Target 12 of the GBF lays emphasis on enhancing green and blue spaces in cities and urban planning for human well-being and biodiversity conservation. Goal 11 of the United Nations Sustainable Development Goal also states the importance of making cities and human settlements safe, resilient and sustainable. But, still, urban biodiversity is under great threat with unplanned development and human greed.
Green space in urban sprawls
Almost half the world's population lives in urban areas, a percentage that is expected to rise to 70% by 2050. City spaces are of premium value and face competing demands. In such a situation, do we have space for greenery? The answer is yes if you consider the range of benefits urban biodiversity offers.
First, health benefits. Urban trees provide provisional services such as food, fibre and water, minimise the urban heat island effect (a much discussed topic) and help in flood control. They help in temperature control, pollution abatement, water conservation and carbon sequestration, and keeping carbon dust and suspended particulate matter in check. Tree lines of a 10 metre width can reduce noise pollution by 5 decibels. In Frankfurt, green belts were shown to reduce the temperature by 3.5° C and increase the relative humidity by 5% when compared to the city centre. Green spaces also provide much needed recreational and spiritual services in the form of parks in what would otherwise be concrete jungles.
Second, economic benefits. Theodore Endreny, Professor of Water Resources and Ecological Engineering, State University of New York College of Environmental Science and Forestry estimated the value of annual services provided by mega city trees to be around $9,67,000 (₹8 crore) per square kilometre of tree cover. Therefore, protecting existing greenery, pursuing the development of parks and new urban green spaces, establishing tree avenues along the roads, and conserving natural rivers and water bodies should be undertaken. The key element of developing green infrastructure is promoting community health and well-being.
In its latest report, the Forest Survey of India has estimated the average forest cover in leading urban cities to be only 10.26% of their geographical area (Mumbai 25.43%; New Delhi and Hyderabad 12.6%, Bengaluru, Chennai and Ahmedabad 6.85%, 4.66% and 3.27%, respectively). Chennai and Hyderabad have lost 2.6 and 1.6 square kilometres of forest cover between the 2021 and 2023 assessments.
The GBF gives a framework to urban planners for biodiversity conservation in cities by protecting blue and green spaces and developing new ones. It suggests enhancing native biodiversity, ecological connectivity and improving human health and well-being.
In this context, the UN Habitat's 3-30-300 prescription is relevant. The principle is: Every home, workplace, or school should have a view of at least three established trees. Neighbourhoods should have a minimum of 30% tree canopy cover and a public green space of at least 0.5 to 1.0 hectares, should be accessible within a 300-metre walk or bike ride from every home.
City biodiversity index
A city biodiversity index is prepared based on the present status of the city in terms of three large parameters — the extent of native biodiversity in the city, ecosystem services provided by them and the level of governance of biodiversity. The International Council for Local Environmental Initiative (ICLEI) Asia has prepared a city biodiversity index using 23 indicators for cities such as Kochi, Gangtok and Nagpur. Once the current biodiversity status of the city is assessed through a survey, a local biodiversity strategy and action plan (LBSAP) is prepared to improve the status of the city in terms of biodiversity conservation and sustainable human welfare.
Urban areas have the resilience to support biodiversity if there is an enabling environment. Local biodiversity could be augmented while undertaking plantations in cities. In Chennai, the greening of the Chennai Koyambedu market in 2021 (undertaken by the Care Earth Trust with the financial support of Chennai Metropolitan Development Authority) helped in the natural regeneration of 141 species of higher plants belonging to 39 families and 106 genera within two years. The site also attracted 35 bird and 27 butterfly species that are considered bioindicators of biological diversity. The Koyambedu model mimics a three-storied natural forest which would be better than the Miyawaki model to enhance native biodiversity in small parcels of land available in cities.
The Care Earth Trust prepared a strategy and action plan in 2018 for the Greater Chennai Corporation (GCC) to plant one million native trees in Chennai city over five years. The sprawling Madras Race Club land at Guindy is being transformed into a lake for augmenting groundwater recharge. However, urban development and encroachment has swallowed up many waterbodies in and around Chennai and Bengaluru. The crucial Pallikaranai marsh in Chennai which was once considered a wasteland and garbage dump has been partly restored and declared as a reserved forest (Ramsar site). Most urban waterbodies are losing their ecological integrity due to garbage and sewage pollution. They must be ecologically restored after preventing garbage dumping and treating sewage through conventional treatment or nature-based solutions. Ensuring legal protection to the remaining lakes and waterbodies in urban areas is a necessity before they are lost.
Many independent houses in Chennai have now given way to multi-storeyed flats leading to the disappearance of home garden trees (coconut, mango, jackfruit). This could also be a reason for the reduction in the city's green cover. As a condition to granting planning permission for new structures, the GCC should consider mandating the planting of at least five trees in a plot that measures over 2,400 square feet along the plot boundary. This will help greening the city in a decentralised manner. The horticulture department should also promote roof gardens and kitchen gardens for every household to m cultivate greens and medicinal plants. This will not only help in augmenting city biodiversity but also help in improving the health and well-being of people.
Need for collective action
City managers need to take stringent action against those who destroy greenery and pollute waterbodies. It is heartening that the Supreme Court of India has been tough on the executive for the mass destruction of trees over acres in the Kancha Gachibowli area in Hyderabad, for the development of IT infrastructure. Development should not lead to the wanton destruction of biodiversity. City managers must mainstream biodiversity considerations in decision making, taking a long-term view to achieve sustainable development. The involvement of all stakeholders such as the resident welfare associations, non-governmental organisations and corporates in city greening and protecting waterbodies from pollution and encroachment is important to make biodiversity conservation a mass movement in cities.
S. Balaji, IFS, is presently Co-Chairman, Access and Benefit Sharing Committee of the National Biodiversity Authority, Chennai, and former Principal Chief Conservator of Forests, Government of Tamil Nadu. The views expressed are personal