Spatiotemporal Assessment of Urbanisation and Deforestation Impacts on Forest Structure and Vegetation Health in Ekiti State, Nigeria Using Multi-Sensor SAR, Optical, and GEDI Data.

Oluwafemi David Bejide , Kunle David Emiola, Ojo Davies Ajewole, Hezekiah Daramola Olaniran

Nigeria’s urban population is projected to reach 70% by 2050, highlighting the urgent need for sustainable land management strategies. This study integrates multi-sensor SAR (ALOS PALSAR, Sentinel-1), optical imagery (Landsat, Sentinel-2), and spaceborne LiDAR (GEDI) to quantify the impacts of urbanization and deforestation on forest structure in Ekiti State, Nigeria.
Using Random Forest and Support Vector Machine classifiers, we mapped a net loss of 54,010 hectares of forest between 2007 and 2024. GEDI-derived canopy height analysis revealed a dramatic decline from an average of 7.95 m in 2019 to 1.79 m by 2025. Notably, although 2024 spectral maps achieved 85.3% classification accuracy, validation against a 5 m LiDAR height threshold yielded a User’s Accuracy of only 38.18%, exposing a “Spectral–Structural Paradox” where apparent greenness masks underlying biomass collapse.
Urbanization in Ekiti is dominated by inefficient horizontal expansion, as reflected in an Urban Land Consumption Ratio of 3.12, far exceeding population growth. These findings demonstrate that conventional two-dimensional monitoring systematically overestimates forest health in urbanizing tropical regions, underscoring the critical need to integrate three-dimensional structural metrics into national forest inventories and urban planning frameworks to support Sustainable Development Goals 11 (sustainable cities) and 15 (life on land).