Urban Ecosystem Restoration for Climate Resilience, and Co-benefits: an Integrated Assessment of the UNESCO World Heritage Site, New Delhi, India

Cities in the Global South face increasing environmental challenges due to severe air pollution, rapid land-use change, and rising urban heat stress. In this context, restored urban ecosystems have become essential nature-based solutions to protect human health, improve regulating services, and act for climate change mitigation. The present study considers Sunder Nursery, the UNESCO-linked World heritage site near the densely populated Nizamuddin area in New Delhi, India. It serves as a model urban greenspace offering sustainability benefits that align with SDGs 3, 11, 13, and 15.

A detailed ecological survey of 661 trees representing 105 species is the foundation for the i-Tree Eco assessment. The site features a diverse, mostly native tree community, including Azadirachta indica, Holoptelea integrifolia, Ficus religiosa, Ficus virens, Albizia lebbeck, Anogeissus pendula, and Diospyros montana. This layered canopy, which includes saplings and trees taller than 29 meters, provides strong regulating services. Preliminary i-Tree Eco findings of study site indicate an annual removal of approximately 50 ± 8 kg PM₂.₅, 770 ± 120 kg PM₁₀, 120 ± 20 kg NO₂, 170 ± 25 kg O₃, 55 ± 8 kg SO₂ and about 60 ± 3 tonnes of oxygen per year. This indicates a clear improvement in air quality through pollutant filtration and support for respiratory health in Delhi's polluted environment. The trees also store about approximately 335 ± 25 tonnes of carbon and sequester approximately 22 ± 2 tonnes per year. This offers substantial carbon-service benefits that help with long-term climate change mitigation by stabilizing carbon stocks and reducing urban CO₂ emissions. These results highlight how restored native urban forests strengthen climate resilience and air quality regulation, which are crucial parts of the study’s objectives.

To evaluate human-centered co-benefits, a Scenic Beauty Estimation was done using 17 representative landscape units from water bodies, heritage lawns, native woodland patches, and mixed plantings. 92 respondents rated these landscape units on a 5-point scale were additionally asked about the sense of mental restoration and well-being they experience in natural heritage settings like Sunder Nursery. Scenic Beauty score show a strong preference for native-dominated, structurally diverse, and water-associated landscapes (mean = 4.32). In contrast, homogenized or exotic-dominated areas scored lower (mean = 3.41). The overlap of high scenic beauty, native biodiversity, strong regulating services, and along with reported feelings of calmness, relief, and psychological comfort suggests that restored ecosystems also serve as cultural landscapes, supporting mental well-being, appreciation of heritage, and aesthetic value.

Thus by integrating ecological modeling with perceptual responses, this study demonstrates that the restored urban ecosystems such as Sunder Nursery can enhance air quality, climate resilience, cultural value, and human well-being at the same time. These findings highlight the urgent need to scale up native tree restoration and heritage-linked ecological planning as practical strategies to tackle persistent urban challenges like pollution, heat stress, and the loss of accessible, healthy green spaces.