Ventilators For A Burgeoning City

Divya Mehra

Delhi, the capital of India, is the second-largest city in the country and one of the fastest-growing urban metropolises, catering to a population of more than 16.76 million people (Census, 2011). The pressures of a growing population have led to unbounded urban sprawl, and over the last six decades, agricultural and fallow lands have been converted into urban built-up areas which have directly and indirectly affected the forest in and around the city. According to the draft Revised Regional Plan for Delhi – 2021, the built-up area in the Delhi NCR region has gone up by 34.6% since 1999, while green areas and water bodies have reduced substantially by 22.5% and 5.9% respectively.

Infamous for its high pollution level, dust, noise and crowd, the city is surviving on the few ecological hotspots that are acting as ventilators for the city. These ecological hotspots provide numerous ecosystem services such as improving air quality, climate regulation, carbon sequestration, water purification, pollination, prevention of erosion, etc. These ecological hotspots are predominantly governed by the two prominent geographical features – (i) the Ridge, consisting of forests in the foothills of the Aravalli range, entering the city from the south and exiting it from the north, and (ii) the river Yamuna which flows on the eastern fringe of the city (Dua & Dua, 2015).

Lying in the semi-arid belt of Northern India, Delhi is home to Northern Tropical Thorn forests (as per Champion & Seth forest classification) – forests that are open, with low density of short trees, generally belonging to thorny leguminous species. The city is also known for its wetlands that have their own bio-geographical heritage and provide numerous ecological services for the city. Even though the natural areas in the city have largely taken an urban form with paved walking and cycling tracks, benches and rain shelters, these areas play a crucial role in maintaining Delhi’s environment and provide a natural escape to the residents from the hustle and bustle of the city. In this blog, I will be listing a few important ecological hotspots such as biodiversity parks, wetlands, and forested areas that are located in and around the city.

Forest Cover in Delhi (Source: Forest Survey of India Report, 2017)

Asola Bhatti Wildlife Sanctuary: It is located in South Delhi district along the Delhi – Haryana – Faridabad – Gurgaon inter-state border, and is an extension of the Aravalli hills. It forms a part of the Southern Ridge forest covering an area of 32.71 Km2. It is the only wildlife sanctuary situated in NCT of Delhi having a tropical dry thorn forest with open vegetation. The forest has undergone massive open cast mining of feldspar (for preparation of high-grade pottery) and subsequently for quartzite (building material) (Sharma et al., 2017). In 2002 the illegal mining in this area was banned and subsequently led to the natural rejuvenation of this forest. There are about 193 species of birds reported from Asola along with a large number of medicinal plants, more than 80 species of butterflies and hundreds of insects.

Jahanpanah City Forest: It is the extension of the southern ridge forest spread across 435 acres of land and offers a natural escape to locals. People visit the forest for morning walks, bird watching and to breathe some fresh air. Even though this forest is mostly manicured, there are still a few trails that have been left wild.

Rajokri Protected Forest: It is a green area interspersed with several small villages, and is located amidst the famous farmhouses of Delhi. It also has a small reservoir which attracts numerous bird species. One can sit near the lake and experience peace and calm.

Sanjay Van: It spreads across 783 acres of land, and forms a part of the south-central ridge which is located near Mehrauli and Vasant Kunj. It is a densely wooded area dominated by vilayati kikar (Prosopis julifora) which is an invasive species. This species was introduced by the British in Delhi in the process of increasing the green cover. Lacking natural competitors, this species has taken over most of the forest areas of Delhi resulting in the exclusion of several native tree species.  Nevertheless, this patch of forest supports several bird species such as Purple sunbird, Brahminy starling, Indian silverbill, Rufous treepie, etc. It also provides a natural habitat for the Nilgai, Golden jackal, Snakes and several varieties of butterflies. The forest also has historical significance as the ruins of the first city of Delhi can be found here.

Central Ridge: It was converted into a reserved forest in 1914, when the Viceroy, Lord Hardinge, initiated afforestation in the area. The idea was to create a backdrop of the green lush forest behind the Government house for the imperial capital (Bhaviskar, 2018). Prosopis julifora was introduced to create the evergreen forest, which later became invasive resulting in the removal of native species. The forest is mostly shaped by human intervention and houses the Budha Jayanti Park, which is famous for the sapling of the holy Bodhi tree planted by former Prime Minister, Lal Bahadur Shastri.

Northern Ridge:  It is located near Delhi University, North Delhi, and is a highly managed forest, which was domesticated by clearing the under-storey of shrubs and creepers. Dominated by Prosopis julifora, the forest is home to several species of birds and is infested by Rhesus macaques that are proliferating due to the easy availability of food (bananas) that are offered by the locals. The forest is used by fitness enthusiast, morning walkers, birdwatchers and young students from the university to experience the ‘wilderness’.

Yamuna Biodiversity Park: It is a recently restored wetland, developed on the Yamuna flood plain’s upstream area – Wazirabad. It serves as an ideal habitat for several residents and migratory bird species because of the wetland and grassland ecosystems. As part of the restoration plan, several native tree species were also planted to rejuvenate the natural area. Gradually, the park is becoming one of the most visited natural areas in the city.

Okhla Bird Sanctuary: It is located on the outskirts of Delhi at the entrance of Noida in Gautam Budha Nagar. The wetland was formed due to the formation of the Okhla Barrage, which provides ideal habitat to more than 322 resident and migratory bird species. It is one of the 466 IBA (International Bird Area) sites in India. It is the most famous birding destination in the city.

Even though the above list suggests a good number of natural ecological features in the city, most of these are fragmented.  Although these small patches help in maintaining the local environment, they are unable to support the growing urban pressures on the city’s air and water quality.  Due to historical interventions, the quality of these forests were also compromised. Most of them are affected by invasive species such as Prosopis julifora, Lantana camara, Water hyacinth, etc. Interventions are necessary to deal with the issues of invasive species; to improve the quality of the forest; and to act as an effective carbon sink for a city with 69.4 million tonnes of carbon emission per year (Goswami & Maurya, 2019). There is a need to create continuity between forest patches and other ecological features of the city so that they can support biodiversity in large numbers.


  • Sinha, G.N. (Ed.) (2014). An Introduction to the Delhi Ridge. Department of Forests & Wildlife, Govt. of NCT of Delhi, New Delhi.
  • Dua, B.S. & Dua, G.W. (2015). Delhi’s greener past: A map to make us think. Retrieved from
  • Ministry of urban development, Government of India. (2013). Draft Regional Plan – 2021: National Capital Region.
  • Ministry of environment, forest and climate change, forest survey of India. (2018). Forest survey of India report- 2017.
  • Bhaviskar, A. (2018). Urban jungles: wilderness, parks and their publics in Delhi. Economic political weekly.
  • Sharma, V. et al. (2017). Monitoring post mining forest dynamics of the tropical thorn forest in Asola Bhatti Wildlife Sanctuary, India using multi-temporal satellite data. International journal of applied environmental sciences. 12(5). 1031-1044.
  • Goswami. S & Maurya. M, (2019). India’s emission capitals. Down to earth. Retrieved from

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