Exploring the impacts of urban expansion on green spaces availability and delivery of ecosystem services in the Accra metropolis

Abstract

As Accra, Ghana's capital city, expands at an unprecedented rate, the fragmentation and loss of natural and semi-natural ecosystems may be the greatest challenge to achieving sustainable development. This study investigates the impact of Accra's growth and expansion on its natural green spaces, availability, and ecosystem services delivery. The study uses remotely sensed imageries (Landsat 1991–2018) for land use change analysis, the i-Tree Canopy model to quantify and value of urban ecosystems and stakeholder interviews to explore perceptions on green space value. Results showed that the overwhelming number of stakeholders understand and are aware of the beneficial values of urban green spaces but highlight poor planning, coupled with land tenure challenges, as a threat to the conservation of green spaces. Land use and land cover change analysis shows that the urban built environment has expanded from 55.1% to 83.79% at the expense of the natural environment, including green spaces, which have declined from 41% to 15% over 27 years. Existing areas of green spaces, including the Achimota forest, the University of Ghana campus and street trees on major roads, were valued at US$37,610,980 for carbon sequestration and storage, US$1,478,173 for air pollution regulation and US$458 for avoided runoff. A rapid assessment of the availability, accessibility and management of urban green spaces in the Accra metropolis can be an essential step towards identifying and mapping their consumptive and non-consumptive use-value and introducing appropriate interventions necessary for enhancing the city's resilience in an era of climate change.