Background:
Tropical forests in Sub-Saharan Africa face rapid and often irreversible transformation due to population growth, agricultural expansion, and illegal logging. Nigeria exhibits some of the highest deforestation rates globally, and protected areas such as the Okomu Forest Reserve (OFR) continue to experience severe anthropogenic pressure. Limited high-resolution, long-term data on forest loss and gain constrain conservation planning and enforcement, highlighting the need for robust spatiotemporal assessments of forest dynamics.

Objectives:
This study aims to quantify annual and cumulative forest loss and gain in OFR from 2000 to 2024 using the Hansen Global Forest Change dataset. It has been hypothesized that forest loss significantly exceeds gain, leading to fragmented regrowth and persistent net forest cover deficits, with implications for biodiversity, carbon storage, and ecosystem resilience.

Methods:
Forest dynamics in the OFR, south-western Nigeria was assessed from 2000 to 2024 using the Hansen Global Forest Change dataset (30 m resolution) within Google Earth Engine. Forest was defined as ≥30% canopy cover in 2000. Annual and cumulative forest loss and gain were calculated by overlaying the forest mask with the loss, gain, and lossyear layers. Net forest change was computed as gain minus loss. Spatial outputs were exported as GeoTIFFs and summarized in tabular form. While high-resolution, satellite-based data may underrepresent small-scale disturbances; this approach provides consistent, multi-decadal insights into forest cover trends in a protected tropical landscape.

Results:
In 2000, OFR contained 99,840 ha of forest. Between 2001 and 2024, 17,262 ha (17.3 %) were lost, while only 4,100 ha (4.1 %) regenerated, resulting in a net decline of 13,162 ha (13.2 %). Forest loss was spatially concentrated along the eastern and north-eastern boundaries, with scattered interior clearings, reflecting ongoing agricultural expansion, logging, and human encroachment. Regrowth was fragmented and localized, primarily in peripheral or abandoned areas, insufficient to restore ecosystem function. These patterns indicate progressive fragmentation of interior forest, reduced habitat connectivity, diminished carbon storage, and heightened vulnerability of wildlife. Annual loss varied, with peaks in 2001, 2002, 2013, 2017, 2018, and 2024, highlighting persistent, rather than episodic, disturbances.

Conclusion:
This study confirms that OFR has undergone substantial forest degradation from 2000 to 2024, with net loss, limited regrowth, and fragmentation threatening biodiversity, carbon storage, and ecosystem stability. Notably, gaps remain in detecting fine-scale disturbances and understanding socio-economic drivers of forest change, highlighting unresolved challenges for comprehensive conservation planning and effective ecosystem management.