Quantifying ecosystem carbon storage, tree diversity, and carbon credit potential in the urban semi-arid forests of Delhi, India

Urban forest plays crucial role in enhancing biodiversity, mitigating climate change, and improving overall urban environments. Despite growing recognition of their role in climate mitigation, limited studies have comprehensively quantified tree diversity, ecosystem carbon pools, and carbon credit potential in semi-arid urban ecosystems like Delhi. This study focusses on quantifying tree diversity, carbon storage, and carbon credit potential in the urban semi-arid forest of Jawaharlal Nehru University, Delhi. The research assessed carbon storage in tree biomass, litter, understory, and soil organic carbon (SOC) including microbial biomass carbon (MBC), to evaluate their contributions to carbon stocks and their economic potential through carbon credits. Tree biomass and carbon stock were estimated using species-specific allometric equations and wood density values. Soil samples were collected from each plot at a depth of 0–30 cm and analyzed for organic carbon using the Walkley-Black method. The monetary value of sequestered carbon was calculated by multiplying the total carbon stock by the prevailing rate in the voluntary carbon market (USD per ton of CO₂ equivalent). The study identified 11 dominant tree species with a density of 826 individual's ha⁻¹ and a basal area of 18.01 m² ha⁻¹. Azadirachta indica and Acacia nilotica exhibited the highest CO₂ sequestration potentials at 55.10 Mg CO₂ ha⁻¹ and 54.43 Mg CO₂ ha⁻¹, correspondingly to economic values of $771.40 and $762.02 ha^-1. In contrast, Cassia fistula showed the lowest CO₂ sequestration potential at 0.23 Mg CO₂ ha⁻¹, with a value of $3.22 ha^-1. The SOC pool was the largest contributor, accounting for 43.21 % of total carbon storage, with 149.73 Mg CO₂ ha⁻¹, valued at $ 2096.20 ha^-1. Understory vegetation, MBC, and litter also contributed significantly, underscoring the importance of both above- and below-ground components in urban carbon dynamics. The findings underscore the potential of urban forest for carbon sequestration and carbon credit generation, advocating the need for strategic urban planning that integrates green infrastructure to support sustainable development in cities like Delhi.