A fully grown palash tree at a biodiversity park in Delhi may be able to store around 222.14 kg of carbon, capturing and storing around 13.57 kg every year. This contribution of the palash tree, a deciduous tree with bright red or orange flowers, to carbon sequestration is among the preliminary findings of an ongoing study on the carbon stored and sequestered by trees at the Aravalli Biodiversity Park, and the contribution of the trees at the park to water recharge. A sample of around 829 trees, 15 to 18 years old and belonging to 72 species, across 83 plots at the park was selected. Based on this, it was estimated that the total number of fully grown trees on 500 acres of the park was 2,02,100 trees. Calculations then showed that over 2 lakh trees can store 9,107.90 tons of carbon. These trees can also capture and store (or sequester) around 1253.07 tons of carbon annually, the preliminary findings show. Carbon storage is the amount of carbon that is present in the tree at a point in time and carbon sequestered is the amount of carbon that the tree collects over one year, explained Yamini Gupt, professor at the Department of Business Economics, Delhi University, who is collaborating with the scientists at the biodiversity park for the study. A price has also been attached to this carbon. While cumulative carbon stored in these trees is worth Rs. 12.35 crore, what is sequestered annually is worth around Rs. 1.69 crore. These figures are based on the price of a ton of carbon in the international market, Professor Gupt explained. “This is based on carbon credits, that is, how you exchange one ton of carbon in the market. This is based on the international price for one ton of carbon that the software is using,” she said. Data collected on the trees in the sample was fed into a software, the i-Tree Eco Software Suite developed by the United States Department of Agriculture Forest Service, to arrive at estimates for the ecosystem services provided by these trees. The highest amount of carbon was found to be stored in the palash trees — 222.14 kg — followed by arjun trees that store 186.67 kg, and the Salvadora persica or peelu trees that store around 120 kg. The amount of water that can be recharged by the presence of these trees across 500 acres was found to be around 1,10,977 cubic feet per year. The “pollution removal efficiency,” which is the ability of these trees across 500 acres to remove gaseous pollutants, was found to be 14.627 tons per year, which was found to be worth around Rs 1.84 crore, which means that it could cost Rs 1.84 crore to otherwise reduce this pollution, Professor Gupt said. The Aravalli Biodiversity Park was set up in 2005 and covers around 692 acres across Vasant Vihar, Vasant Kunj and Mahipalpur. At the park, the largest of seven such biodiversity parks in the city, efforts have been made to revive Aravalli vegetation over an area that was previously used for mining. Faiyaz Khudsar, scientist in-charge of the Biodiversity Parks Programme of the Centre for Environment Management of Degraded Ecosystems, said more data is being collected for the study before it is sent to be considered for publication in scientific journals. “It can tell us how these trees reduce carbon footprint and help recharge water in an arid zone like Delhi. Data from this study on trees like palash and hingot can now be added to the global data set on which trees can store how much carbon. At present, these trees are not in the global data set,” Khudsar said. Information on the diameter of the trunk of the trees at around 6 feet and the canopy of trees was used for the calculations. The contribution of younger trees, herbs, shrubs, and grass to aspects like reducing surface run-off of water and recharging of water is also being estimated, Khudsar said.
