Mumbai has embarked on its first tree census in nearly eight years, with 64 botanist teams meticulously documenting trees across the city. The exercise, which began in February, is expected to last two years and covers not only public spaces but also private properties, including housing societies, institutional campuses, and restricted defence and airport zones.
Scientific Criteria for Tree Inclusion
Surveyors focus on specific measurements to determine which trees qualify for the census. A mango tree at the civic-run Pramod Mahajan Garden in Dadar, for instance, is assessed for its height, girth, and canopy. A measuring tape is carefully wrapped around the trunk, but only if the tree meets the Brihanmumbai Municipal Corporation’s (BMC) qualifying conditions: a minimum girth of 30 centimetres at chest height or a height of at least 2.5 metres. Once the readings are entered into the Treecotech app, the team moves on to other species, such as a tamarind tree and a fishtail palm.
“People often think we count only large trees, but there is a scientific criterion,” explains Sarfaraaz Khan, a horticulturist at the garden from SAAR IT Resources Pvt Ltd, the agency appointed to conduct the census. The app standardises data collection across the city, automatically generating botanical names when a local or common name is selected from a dropdown menu. Surveyors then record measurements, canopy diameter, distance between adjoining trees, and the tree’s physical condition.
Data Collection and Challenges
For every tree documented, surveyors physically record girth, canopy spread, and height, along with species name, health condition, ownership, balance, mechanical damage, and geographic coordinates via a GIS-enabled internal app. The process takes two to three minutes per tree. This time, there are also plans to assign QR codes using synthetic paper to large trees, along with unique identification numbers.
Sunil Rathod, deputy superintendent of gardens, notes that dense urban neighbourhoods present unexpected challenges. “In gardens and open patches, the work moves fast. But in private societies and restricted establishments, permissions take time. Hence, our surveyors have been provided with a letter from the BMC garden department asking the establishments to cooperate with them,” he says. Defence land, airport premises, and gated residential compounds are among the locations where access is a hurdle.
Ecological Patterns and Historical Insights
Despite logistical difficulties, the census is already revealing striking ecological patterns. In Parsi colonies, for example, a concentration of uncommon species such as baobab trees and branching palms has been found. Surveyors believe this reflects the community’s long association with trade and its culture of preserving green spaces. “Parsis who travelled overseas for trade would often carry saplings from here on their boats and return with tree species from the countries they visited. That is probably why many Parsi colonies today have such unique varieties of trees,” says a surveyor. Strong local resistance against tree cutting or concretisation around roots is also common in these neighbourhoods, making tree cutting comparatively rare.
Importance of the Census
Jitendra Pardeshi, BMC’s superintendent of gardens, emphasises that the census is crucial not just for counting trees but also for understanding Mumbai’s changing urban ecology. “The data collected will eventually help BMC map tree diversity,” he says. The last enumeration in 2018 recorded about 29.8 lakh trees within city limits, which rose to nearly 33.7 lakh after Aarey Colony’s inclusion. This time, officials expect numbers to increase due to urban plantations and Miyawaki forests developed across the city.
Ecologist Anand Pendharkar, chief executive officer of Sprouts Environment Trust, stresses that physical verification by experts remains crucial, particularly for accurate species classification. “The tree census should become a continuously monitored public exercise rather than a one-time counting activity. Species identification is extremely important because the climate benefits of indigenous and exotic trees are very different.” He suggests that institutions and private establishments be encouraged to upload their tree data onto a central platform for independent verification. He also calls for greater scrutiny of exotic species, noting that certain species such as eucalyptus adversely affect the soil and surrounding flora, and that ornamental trees like gulmohar, though aesthetically attractive, should gradually be discouraged in favour of native species.
Participatory Approach and Future Plans
Pendharkar says the exercise could become more participatory by involving botany colleges, citizen groups, and local communities. “The moment people begin observing trees closely—when they flower, how they grow, why they fall—society becomes more engaged with urban ecology. Mapping trees architecturally and scientifically is essential for long-term planning and safety.”
Back in the Dadar garden, the team finishes documenting another tree before moving ahead with tapes, smartphones, and clipboards in hand. Outside, commuters rush towards the station, largely unaware of the mammoth exercise underway.
