Urban Land Expansion and Spatiotemporal Dynamics of Urban Green Spaces in Africa

Urban growth is crucial for economic advancement, but it results in the fragmentation and depletion of natural and semi-natural ecosystems, which are often replaced by built-up areas. The balance between urban green spaces (UGSs) and impervious surfaces (ISs) is a key factor in urban areas for evaluating the environmental quality of cities and addressing the challenges associated with global environmental changes. This study analyzed African urban expansion dynamics from 2000 to 2020, which resulted in changes in the proportion of green spaces and built-up areas. Urban areas in Africa grew significantly, expanding by 207% from 28,461.7 km2 in 2000 to 87,337.2 km2 in 2020. The period from 2010 to 2020 was crucial, witnessing a substantial urban expansion of 33,676 km2. The urban expansion in this period was found to be positively correlated with the population growth. Most urban areas in Africa are small, with about 86% being less than 10 km2 in size. Initially, urban growth led to more impervious surfaces and less green spaces, but the following decade showed a shift towards greener urban areas. There was a 20% increase in the share of urban green spaces (UGSs) and a decrease in impervious surfaces, enhancing urban greenery. Green spaces increased by 225.2%, reaching around 47% of urban areas by 2020. Forested areas expanded, grasslands declined slightly, and croplands increased marginally, indicating a trend towards greener urban regions in Africa.