Spatial Analysis of Urban Heat Island Effects on Horticultural Microclimate in Lagos Metropolis

Urban heat islands (UHI) represent a growing environmental challenge in megacity environments, with documented impacts on plant phenology, crop stress, and the productivity of urban horticultural systems. Lagos Metropolis, Nigeria's largest city, exhibits pronounced UHI effects attributable to rapid urban expansion, surface imperviousness, and reduced vegetation cover. This study applies spatial analysis to characterize the magnitude and distribution of urban heat island effects across Lagos and assess their influence on microclimate conditions in urban horticultural production zones. Landsat 8 thermal infrared imagery was processed to derive land surface temperature maps for Lagos across dry and wet seasons. Ground-truthing measurements of canopy temperature, relative humidity, and photosynthetically active radiation were collected at 30 urban farm sites stratified across high, medium, and low UHI intensity zones. Generalized linear models were used to relate UHI intensity to horticultural microclimate parameters and vegetable yield observations. Results indicate a 3.2 to 5.8 degree Celsius temperature elevation in high UHI zones relative to peri-urban agricultural areas, associated with significantly reduced vegetable yield and increased water demand. The study recommends incorporation of green infrastructure planning, including shade trees and rooftop gardens, into Lagos urban heat mitigation strategies to sustain urban horticulture productivity. Keywords: urban heat island, spatial analysis, urban horticulture, Lagos, microclimate