Plant Diversity, Carbon Storage and Sequestration Potential of Urban Green Spaces: A Climate Change Mitigation Tool in the Republic of Niger, West Africa

Abstract

Urban green spaces contribute to biodiversity conservation and climate regulation, but their woody plant composition and carbon sequestration potential remain insufficiently documented in the Republic of Niger. This study assessed woody plant diversity, biomass, carbon storage and carbon dioxide sequestration within public green spaces in Niamey, Maradi, Tahoua and Zinder cities. Woody plants with a diameter at breast height of at least 3 cm were inventoried using a stratified random sampling approach across selected categories of public green space. Measurements included species identity, total height, diameter at breast height and green space area. In total, 15,719 woody individuals were recorded, representing 47 species, 41 genera and 24 botanical families. Fabaceae was the most represented family, accounting for 23.40% of recorded species. The flora was dominated by dicotyledons, which accounted for 93.62% of the floristic assemblage. Azadirachta indica was the most abundant species, representing 81.86% of all inventoried woody individuals. Total biomass varied across green space types, ranging from 3.83 t/ha in parks to 299.55 t/ha in memorial green spaces. Overall carbon stock was estimated at 747.81 tC/ha, corresponding to 2,744.46 tCO₂/ha of sequestered carbon dioxide. The findings show that public green spaces in Nigerien cities support woody plant diversity and provide measurable carbon storage benefits, highlighting their relevance to urban climate mitigation and sustainable planning.