Assessing canopy height and aboveground biomass dynamics in Southwestern Nigeria using GEDI LiDAR and multi-sensor Earth observation

Oluwafemi David Bejide , Kunle David Emiola, Hezekiah Daramola Olaniran

Accurate monitoring of forest degradation is important for understanding changes in forest carbon storage and associated carbon losses. Although canopy height derived from spaceborne LiDAR provides an important indicator of forest structural condition, estimating canopy height, biomass and detecting their changes in structurally complex tropical forests remain challenging. This study developed a multisensor satellite-fusion approach to predict canopy height and AGB in the tropical forests of Southwestern Nigeria between 2020 and 2025 using GEDI LiDAR and multi-sensor Earth observation data.

Canopy height (RH98) and AGB were modelled independently using machine learning and multi-source predictors. Model performance was moderate (R² = 0.38–0.49 for canopy height; R² = 0.44–0.48 for AGB). Independent comparison with the GLULC canopy-height product (Potapov, 2021) and the ESA CCI biomass product (Santoro and Cartus, 2023) showed moderate and strong positive agreement, with correlation coefficients of R = 0.56 and R = 0.79, respectively.

Both canopy height and AGB declined between 2020 and 2025, with all six states in Nigeria's Southwestern rainforest recording reductions in forest canopy height and aboveground biomass. Biomass-derived CO₂-equivalent stock density decreased from 384.68 MgCo₂e/ha in 2020 to 336.87 MgCo₂e/ha in 2025, which represents a reduction of 47.81 MgCo₂e/ha (12.43%).

These findings demonstrate the value of integrating biomass indicators for characterising forest degradation and carbon dynamics. The decline in biomass and associated CO₂-equivalent stocks highlights implications for Nigeria’s REDD+ efforts. GEDI LiDAR and multi-sensor Earth observation data provide a scalable approach for monitoring forest structure, biomass, and carbon dynamics