Integrating Urban Green Infrastructure into Climate Change Adaptation: Ecosystem Biodiversity, Land Surface Temperature, and Malaria Risk in Ibadan, Nigeria

Abstract

Rapid urbanisation across sub-Saharan Africa is reshaping natural landscapes with significant consequences for ecosystem stability and public health. In Nigeria, malaria remains a major health burden, yet limited longitudinal evidence links urban green infrastructure (UGI) change to malaria risk at the intra-city scale. This study investigates the spatial and temporal relationships
among UGI, land surface temperature (LST), and malaria incidence across eleven local government areas (LGAs) of Ibadan, Nigeria, using multi-temporal Landsat-derived NDVI, LST retrieval, and facility-based health records spanning 2013–2023. Results reveal that nine of eleven LGAs experienced net vegetation loss over the study period, with the steepest declines in core urban
LGAs: Ibadan North-East (NDVI = ?0.12) and Ibadan South-East (NDVI = ?0.10). Urban core NDVI values remained consistently low (0.10–0.22) compared to peri-urban values (0.24–0.40). The UGSI–LST relationship was strong and negative throughout the study period (r = ?0.99 in 2013; ?0.94 in 2023; all p < 0.001), with core urban LGAs recording mean LST values 4.3 4.6°C above peri-urban LGAs in all three reference years. Malaria incidence rates were persistently higher in core urban LGAs (mean 285.4 per 1,000 in
2023 vs. 86.6 in peri-urban LGAs), with all five core urban LGAs recording higher rates in 2023 than in 2013. Critically, the green space–malaria incidence correlation weakened from r = ?0.77 (p < 0.01) in 2013 to non significance in 2023, while population density emerged as the strongest and most temporally stable predictor of malaria burden across all study years. These findings demonstrate that declining and poorly managed UGI intensifies urban heat and contributes to uneven malaria vulnerability, but that the health effects of vegetation are mediated by management quality and population density rather than quantity alone. Integrated, equity-focused urban green infrastructure planning is essential to reduce climate-sensitive disease risk in rapidly expanding West African cities.