Koffi Akpagana

In Togo, the cities of Lomé and Kara are undergoing rapid urbanisation driven by strong population growth and the expansion of urban built-up areas, leading to significant reductions in urban green spaces (UGSs). UGSs are vital for climate regulation and human well-being by mitigating urban heat, improving air quality, and supporting mental health. This urban expansion directly replaces vegetated areas with impervious surfaces, diminishing UGS and their associated ecosystem services. Consequently, climatic vulnerability has increased, highlighting the need for sustainable urban development and UGS conservation. This study examines UGS spatiotemporal dynamics using Landsat imagery from 1988, 2000, 2012, and 2022, applying a supervised image classification approach with the maximum likelihood algorithm. Post-classification change detection quantified UGS loss. Additionally, vulnerability models for 2022, 2060, and 2100 were developed using Shared Socioeconomic Pathways (SSP 2.45 and SSP 5.85) and a multifactorial modelling approach. The results reveal a decline in UGSs from 85.98% to 40.78% in Lomé and from 93.99% to 36.68% in Kara between 1988 and 2022, primarily due to urbanisation. Vulnerable zones, currently in UGSs, risk disappearance by 2060–2100, exacerbating climate risks. Urgent measures are needed, including conservation policies, UGS creation, and community awareness to promote urban sustainability.

The cities of Lomé and Kara in Togo are undergoing rapid urbanisation due to strong demographic pressure, leading to a reduction in Urban Green Spaces (UGSs), which are essential for climate regulation and urban well-being. This situation highlights the climatic vulnerability of these areas, making it imperative to reconcile urban development and the preservation of UGSs for urban sustainability. This study contributes to the sustainable conservation of UGSs in Togo. More specifically, it uses Landsat images from 1988_2000_2012_2022 to analyse the spatiotemporal dynamics of UGSs in Lomé and Kara and develops vulnerability models in 2022 and for the 2060 and 2100 horizons based on SSP 2.45 and SSP 5.85 climate scenarios via the multifactorial method. The results revealed a reduction in UGSs in Lomé (from 85.98% in 1988 to 40.78% in 2022) and Kara (from 93.99% to 36.68%), mainly due to urban expansion. Low- and medium-vulnerability zones, often located in UGSs, will likely disappear by 2060 and 2100, accentuating urban climatic vul-nerability. Hence, there is an urgent need to implement conservation policies, create new UGSs, and increase awareness among city dwellers.

Urbanization is a current concern, particularly in Africa, where it is expected to continue and increasingly threaten the effectiveness of plant biodiversity, natural carbon sinks, and the sustainability of cities. This paper investigates the structural parameters and carbon storage potential of trees in the land use units of the city of Cotonou in southern Benin. A total of 149 plots at 2500 m² each were randomly generated, and trees with a diameter ≥ 10 cm were inventoried. ANOVA revealed that the means of structural parameters (diameter and height classes) and carbon stock rate varied significantly (p < 0.001) across land use units in the city. Tree basal area is estimated at 4.52 ± 5.24 m² ha⁻¹, with an average of 12.72 (13) feet ha⁻¹. The average diameter of the trees is estimated at 57.94 ± 29.71 cm. Approximately 1000 kg ha⁻¹ (0.94 × 10³ kg ha⁻¹) of carbon is stored in the city of Cotonou. Green spaces (1.21 × 10³ kg ha⁻¹) and roads (1.19 × 10³ kg ha⁻¹) are the units that recorded the highest carbon stocks. Khaya senegalensis, Mangifera indica, and Terminalia mentally lead the top ten species with high stock potential. This study demonstrates the contribution of urban trees to global atmospheric carbon reduction, which varies by species, land use units, and tree density. Future research could investigate an i-Tree Landscape approach for urban carbon estimation. This could reinforce urban carbon data availability for urban ecological planning.

Rapid urbanization and climate change effects may cause dramatic changes in ecosystem functions in cities, thereby inevitably affecting the growth performance of old trees. Few studies have explored species diversity and spatial differentiation in Benin urban areas. This study aims to explore this dimension of urban ecology in order to build resilience to climate change in the city of Cotonou. Its objective was to determine the predominant level of tree diversity in the city’s land use units. The urban green frame was subdivided into six land use units, namely, establishments, residences, green spaces, commercial areas, administrative areas, and roads. The forest inventories were carried out in 149 plots with surfaces evaluated at 2500 m² each. The IVI, an index that highlights the relative density, relative dominance, and relative frequency of species, has been used to characterize the place occupied by each species in relation to all species in urban ecosystems. This shows ecological importance through the diversity and quality of ecosystems, communities, and species. A total of 62 tree species in 55 genera and 27 families were recorded. The results show that the flora of the city of Cotonou is characterized by a strong preponderance of exotic species with some differences in species presence. The most abundant species with high ecological importance (IVI) in the different types of land use of the city are Terminalia catappa (IVI = 121.47%), Terminalia mantaly (IVI = 90.50%), Mangifera indica (IVI = 64.06%), and Khaya senegalensis (IVI = 151.16%). As the use of ecosystem services is recommended to tackle urban climate hazards, this study shows that direct development of this urban vegetation could improve the resilience of urban life to climate hazards through the provision of urban ecosystem services, potential ecological infrastructure foundations, and urban nature-based solutions.

Rapid urbanization and climate change effects may cause dramatic change of ecosystem functions in cities, thereby inevitably affecting the growth performance of ancient trees. Few studies have explored species diversity and spatial differentiation in Benin urban area. Here, we took Cotonou city to do that. The objective of the study conducted in the city of Cotonou, was to determine the predominant level of plant diversity in the city's land-use units. The urban green frame was subdivided into six land use units, namely establishments, residences, green spaces, commercial areas, administrative areas, and roads. The forest inventories were carried out in 149 plots with surfaces evaluated at 2500 m2 each. A total of 62 tree species in 55 genera and 27 families were recorded. The results show that the flora of the city of Cotonou is characterized by a strong preponderance of exotic species. The most abundant species with high ecological importance (IVI) in the different type of land use of the city are Terminalia catappa (IVI=121.47%), Terminalia mentally (IVI=90.50%), Mangifera indica (IVI=64.06%) and Khaya senegalensis (IVI=151.16%). This study shows that a directed development of this urban vegetation could improve the resilience of urban life to climate hazards through the provision of urban ecosystem services, potential ecological infrastructure foundations and urban nature-based solutions.