Carbon Storage and Carbon Dioxide Sequestration by Urban Tree Cover: Case Study From Varanasi, India

Increasing number of urban settlements is a major contributor to global climate change and has resulted into rising sea level, increasing the frequency of floods and droughts and ultimately decreasing human well-being. Urban areas are likely to account for 68 per cent of the world’s population by 2050, which will result in extensive environmental degradation and ecological destruction. They are considered the major source of carbon emissions because anthropogenic activities such as the heating of domestic spaces and vehicular emissions are concentrated in urban areas. Tree populations in urban areas have a tremendous potential to mitigate emissions through carbon sequestration. However, only a few studies on the quantification of carbon stock in urban vegetation are so far available. There is therefore an urgent need to quantify the amount of sequestered carbon in urban tree cover for better monitoring and management of regional carbon stock. In the present study, we explore the potential of carbon dioxide sequestration in trees at a few sites in the heavily populated city of Varanasi. Our study shows that the carbon stock in both above-ground and below-ground biomass in different sites averaged 1901 metric tonnes of carbon per hectare, with carbon dioxide sequestration of 6977 tonnes per hectare. This indicates that urban tree plantations have a significant potential to sequester anthropogenic carbon locally at source and to stock it in their biomass for long periods of time. Some key recommendations regarding the expansion of urban green cover and the planting of fast-growing native species are offered, in order to enhance carbon dioxide sequestration. © 2022, The National Academy of Sciences, India.