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Ginkgo biloba, popularly known as a “living fossil”, is among the oldest living tree species on Earth, with a lineage that dates back nearly 290 million years. The sole surviving member of an ancient group of trees that existed long before dinosaurs roamed the planet, it now stands witness to a new initiative in a quiet corner of Delhi University’s North Campus: the Carbon Garden.
The Carbon Garden is not an ornamental green space; it is designed as an ecological intervention — a living system engineered to filter pollutants, sequester carbon and restore ecological balance in urban landscapes. At a time when cities such as Delhi are grappling with worsening air quality, the garden aims to offer a nature-based approach to mitigating pollution.
Developed over three years, it houses a mix of plant species, including hydrophytes that thrive in water, xerophytes adapted to arid conditions, mesophytes that flourish in moderate environments, and ancient plant groups such as pteridophytes and bryophytes.
The Carbon Garden has a mix of tree types, ranging from fast growing trees such as casuarina to native canopy builders such as kadamba or burflower trees. They are complemented by ground cover plants and shrubs as well as micro-organisms such as algae, bacteria and fungi. “The careful selection of plant categories play a vital role in maximising carbon sequestration,” says Professor Dinabandhu Sahoo, Head of the Department, Botany, at the university.
“Microorganisms living on plant surfaces help break down toxic gases such as methane and carbon monoxide, converting them into less harmful or even useful compounds. In effect, the garden functions as a natural filtration system drawing pollutants down from the air while simultaneously enriching the soil,” explains Sahoo, who is spearheading the initiative and is also the chairperson of the research and innovation council of the university.
Zoya Khan, an undergraduate botany student at the university says the Carbon Garden is like a living lab. “We can experience what is taught in classrooms and textbooks in the Carbon Garden,” she shares.
Clean air solutions are often viewed through the prism of technology, but Sahoo believes that plants can offer some of the most effective remedies. The Carbon Garden is an attempt to bring that idea to life.
At its core is the understanding that healthy ecosystems depend on the seamless interaction between land and water. While water systems help filter pollutants, store water and regulate moisture, terrestrial systems use that moisture for soil stabilisation, plant growth and carbon sequestration. “Without one, the other system doesn’t function properly,” Sahoo explains.
The garden’s water system is powered by hydrophytes and microalgae such as Canna, Spirulina, diatoms and Chlorella, which store rainwater, clean it, produce oxygen and cycle nutrients. On land, mesophytic trees including neem, peepal, moringa and casuarina stabilise soil while absorbing carbon dioxide and trapping particulate matter. Shrubs and ornamentals such as the snake plant and petunia attract pollinators and help absorb airborne pollutants.
Bryophytes and ferns retain moisture, aid soil formation and support microbial life. Xerophytes such as the prickly pear and aloe vera keep the system functioning during heat and drought, while long-lived gymnosperms such as Ginkgo and sago palm enhance carbon storage and resilience. “Even tree bark plays a vital role,” says Sahoo. “A single square metre of tree bark can host nearly six trillion microbes that consume harmful gases such as methane, carbon monoxide and certain other volatile compounds detrimental to human health.”
An informal study by Sahoo’s department found better environmental conditions within the Carbon Garden than along nearby roads. Morning AQI was 76–81 compared to 133 outside, while PM2.5 and PM10 levels were nearly half inside the garden. Afternoon temperatures were also about 4°C lower inside the garden.
While the findings are encouraging, a comprehensive assessment of the garden’s ecological and environmental impacts is currently being carried out by an independent group of experts.
Scientist Geetha Ramaswami who is the team lead at SeasonWatch by Bengaluru-based conservation and research organisation Nature Conservation Foundation believes that though the Carbon Garden is a good concept, local ecological context should be kept in mind while replicating them in different regions. “Plant species that work in Delhi may not work in Kerala. The focus should be on including local species otherwise it may adversely impact the local biodiversity,” she shares.
“To reap maximum benefit, experts, who understand native biodiversity may be included in the process of developing them,” she says, adding that “some indoor plants are valued for their resilience and ability to provide year-round greenery. Non-native indoor plants (if any) that can become potentially invasive should be introduced thoughtfully and managed with ecological caution. But botanists are aware of these and may be using it judiciously,” Ramaswami adds.
According to World Health Organization estimates, air pollution claims over seven million lives globally each year. With India accounting for roughly 1.7 million of those deaths. Data from IQAir further underscores the scale of the crisis, as nine of the world’s 20 most polluted cities are in India.
A key advantage of the Carbon Garden model, according to Sahoo, is its practicality. Unlike large urban forests, carbon gardens require relatively small parcels of land and can be adapted to schools, residential complexes, office campuses and other public spaces. He says discussions are already underway with civil society groups, resident welfare associations and institutions interested in replicating the model.
One of the largest adoption efforts is being led by the Central Industrial Security Force (CISF) Eastern Sector. “We are developing 44 carbon gardens across Jharkhand, Bihar and eastern Uttar Pradesh,” says Prabodh Chandra, Inspector General, CISF Eastern Sector.
Four such carbon gardens have already been established in Ranchi in Jharkhand, and in Nabinagar, Barauni and Tanda across Bihar and Uttar Pradesh. Work is underway at 40 additional locations in these states. “By the end of this monsoon, we expect all 44 carbon gardens to be operational,” Chandra says.
According to environmental scientist Chirashree Ghosh who is not part of the project, initiatives such as carbon gardens are valuable because they go beyond tree planting and encourage people to engage directly with ecological restoration. “It offers an opportunity to co-create consciously designed eco-spaces, and more importantly create a culture where sustainability becomes second nature,” explains Ghosh.
Banner image: A carbon garden at Delhi University. Image by Dinabandhu Sahoo.
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