Carbon Storage and Sequestration Potential of Urban Trees in Kano Metropolis, Nigeria

Abstract

Urban trees provide important ecosystem services, including carbon sequestration, air pollution mitigation, temperature regulation and biodiversity conservation, and they can support public health and urban climate adaptation. In rapidly urbanising cities such as Kano Metropolis, urban trees represent important green infrastructure for climate change mitigation and environmental management. This study assessed biomass accumulation, carbon storage and CO2 sequestration potential of urban tree species in Kano Metropolis, northern Nigeria. All tree species with diameter at breast height (DBH) >= 10 cm within the sampled locations were identified, and DBH, height, diameters at the base, middle and top, wood density, above-ground biomass, below-ground biomass and total biomass were measured or estimated. Descriptive statistics were used for data analysis. A total of 1,144 individual trees belonging to 31 species and 15 families, including native and exotic species, were recorded. Azadirachta indica had the highest frequency (468 individuals), whereas Ficus platyphylla, Balanites aegyptiaca and Acacia seyal recorded one individual each. Acacia seyal recorded the highest biomass (396.62 kg), volume (524.63 m3), carbon stock (198.31 kg) and CO2 sequestration (727.80 kg), whereas Hura crepitans recorded the lowest biomass (0.86 kg), volume (1.14 m3), carbon stock (0.22 kg) and CO2 sequestration (1.59 kg). The findings indicate species-level variation in biomass accumulation and carbon sequestration, highlighting the need to enhance species diversity and expand urban green spaces in Kano Metropolis.