New Delhi, Jun 22 (PTI) As Delhi braces for the upcoming monsoon, a recent study found that the Aravalli Biodiversity Park helps retain nearly three million litres of rainwater annually, reducing surface runoff that can contribute to waterlogging and urban flooding.
According to the study, the 692-acre restored forest is doing more than providing a patch of green amid the urban sprawl.
It said urban forests with roughly 2.02 lakh trees help prevent nearly three million litres of surface runoff annually, replenishing groundwater reserves and helping slow the movement of rainwater across the ground, allowing more water to infiltrate the soil instead of rapidly flowing over paved surfaces.
The researchers added that the Aravalli Biodiversity Park is located in an important groundwater aquifer recharge zone and plays a key role in replenishing underground water reserves.
The study, titled “Structure, ecosystem services and economic evaluation of native tree diversity: a case study of the restored Aravalli Biodiversity Park, Delhi, India”, was conducted by researchers from the Centre for Environmental Management of Degraded Ecosystems (CEMDE), Biodiversity Parks Programme, Department of Finance and Business Economics and Satyawati College, all affiliated with the University of Delhi.
“Delhi has a dry-winter humid subtropical climate bordering on a hot semi-arid climate and receives an average annual rainfall of 774.4 mm, most of it during the monsoon months between July and September,” the study said.
Besides regulating water, the park also plays a significant role in improving air quality. The study estimated that its trees remove around 126.89 tonnes of air pollutants every year, generating environmental benefits valued at nearly Rs 1.89 crore.
Researchers said the trees help remove particulate matter and other harmful pollutants from the atmosphere. The study noted that structurally diverse urban forests are particularly effective in trapping airborne pollutants and improving environmental quality.
The biodiversity park was also found to function as a growing carbon sink. Researchers estimated that its trees currently store around 8,360 tonnes of carbon, valued at nearly Rs 11.34 crore, while absorbing another 1,236 tonnes of carbon every year as they continue to grow.
The study explained that carbon storage refers to the amount of carbon locked in tree biomass at a given time, while carbon sequestration refers to the annual accumulation of carbon by growing trees. For economic valuation, carbon estimates were converted into carbon dioxide equivalents using a standard molecular conversion factor.
Researchers said such ecosystem services are increasingly important in rapidly urbanising cities where shrinking green spaces and expanding built-up areas often worsen flooding and waterlogging during heavy rainfall.
Researchers found that bigger trees generally store and absorb more carbon. According to the study, trees with thicker trunks, greater height and wider canopies were more effective at capturing carbon from the atmosphere.
Researchers said the significance of these findings becomes clearer when viewed against the park’s past. Located on Delhi’s southern ridge, the area was once a heavily degraded mining site.
According to the study, nearly 80 per cent of the site was covered by abandoned pits created during the extraction of morrum, a reddish gravelly soil used in construction, along with mounds of waste material left behind by mining operations. Much of the land was barren and supported only scattered vegetation.
The area was largely covered by invasive species such as vilayati kikar (Neltuma juliflora) and lantana (Lantana camara), along with a few native species such as white-barked acacia (Vachellia leucophloea), babul (Vachellia nilotica) and adulsa (Justicia adhatoda), the researchers said.
Over the years, restoration efforts transformed the degraded landscape into a mosaic of forests, grasslands and wetlands. According to the study, the park now supports around 700 plant species spread across 20 ecological communities and provides habitat for a wide range of wildlife.
During field surveys, researchers recorded 80 native tree species and found high levels of biodiversity. The study said the wide variety of plant species has helped create a healthy, stable and resilient ecosystem.
According to the study, the dominant tree species in the park include palash (Butea monosperma), Indian elm (Holoptelea integrifolia), white-barked acacia (Vachellia leucophloea) and kadamb (Mitragyna parvifolia).
Researchers said the park’s uneven terrain, shaped by years of mining activity, has created different types of habitats that support a variety of plants and animals. This diversity also helps the park provide important ecosystem services such as carbon storage, air pollution removal and groundwater recharge.
According to the study, forests with a greater variety of native species are generally more resilient and better able to withstand environmental stress. Such forests also support important ecological functions including nutrient cycling, pollination, habitat creation and climate regulation.
The researchers said the findings show how degraded land can be restored using native vegetation to create green spaces that not only support biodiversity but also provide practical benefits such as cleaner air, carbon capture, groundwater recharge and reduced flood risk in cities.
For the study, researchers carried out vegetation surveys across about 500 acres of the park in 2023. They laid 83 quadrats measuring 10×10 metres and recorded 829 trees belonging to 80 species. Using the i-Tree Eco model along with local meteorological and air quality data, the team assessed ecosystem services including carbon storage, carbon sequestration, air pollution removal and avoided surface runoff. PTI SGV KSS KSS KSS
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