Urban forests store carbon worth Rs 4 lakh/hectare: Study

In a city struggling with toxic air and rising temperatures, Delhi’s forests have been quietly storing an underground climate treasure. Researchers from the Jawaharlal Nehru University and the University of Delhi have found that urban forests in the national capital are absorbing massive amounts of carbon in their trees and soil, with the potential to generate over Rs 4 lakh per hectare through carbon credits.

The study said that one hectare of urban forest land inside the JNU campus could store nearly 346.9 tonnes of carbon dioxide equivalent, or around 3,46,900 kilograms. One hectare equals nearly 2.47 acres. Researchers estimated the carbon credit value of this storage at nearly $4,846, or more than Rs 4 lakh per hectare.

According to the study, the biggest carbon storage was happening underground rather than in trees. Researchers said soil organic carbon accounted for more than 43 per cent of the total carbon stored in the ecosystem. The soil alone stored nearly 149.73 tonnes, or around 1,49,730 kilograms, of carbon dioxide equivalent per hectare, with an estimated carbon credit value of nearly $2,096 or around Rs 1.74 lakh per hectare.

Among tree species, neem (Azadirachta indica) and babool (Acacia nilotica) emerged as the strongest carbon absorbers in the forest ecosystem studied by researchers.

The study found neem trees stored 55.10 tonnes, or around 55,100 kilograms, of carbon dioxide equivalent per hectare, with an estimated carbon credit value of over $771, or more than Rs 64,000. Babool trees stored 54.43 tonnes, or around 54,430 kilograms, of carbon dioxide equivalent per hectare, valued at around $762, or over Rs 63,000.

Researchers also found that litter on the forest floor, shrubs, herbs and underground microbial activity contributed significantly to carbon storage, showing that entire forest ecosystems, and not just large trees, help absorb greenhouse gases.

The researchers said urban forests in Delhi could become critical natural buffers against rising emissions and worsening climate conditions in the city if protected and expanded properly.

The study noted that native species such as neem and babool are especially important in semi-arid urban conditions because of their high carbon storage potential and ability to survive harsh climatic conditions.

Researchers also found that forests with greater biodiversity and healthier soil stored more carbon overall.

The findings come amid the Delhi Government’s push to monetise pollution reduction through a Carbon Credit Monetisation Framework approved by the Cabinet in January this year.

Under the framework, pollution reduction achieved through electric buses, plantation drives, solar energy projects and waste management initiatives will be scientifically measured and converted into carbon credits that can be sold in national and international markets.

A carbon credit is essentially a tradable certificate representing one tonne of carbon dioxide removed from the atmosphere or prevented from being released. Governments and companies buy these credits to balance out their emissions.

According to the Chief Minister’s Office, the Environment Department will appoint a specialised agency through a tender process to identify projects eligible for carbon credits and register them under international standards.

Chief Minister Rekha Gupta had said the framework would help Delhi strengthen climate action efforts while also generating additional revenue for development works.

For the study, researchers examined forest patches spread across the 1,019-acre JNU campus (nearly 412 hectares). They created five separate study plots and used stratified random sampling methods to record tree species, trunk diameter, tree height and biomass.

Researchers also collected soil samples up to a depth of 30 centimetres and analysed them in laboratories to measure organic carbon, nitrogen and microbial activity. The study recorded 11 dominant tree species with an overall density of 826 trees per hectare.