Key message <p>Aboveground biomass (AGB) increased from forest edge to forest interior in small forest patches of Western-Africa. In plots of 0.25&#xa0;ha, AGB did not correlate with tree species richness or wood density. AGB in these unprotected forest patches was lower than in the nearby protected forests. AGB obtained from manual inventory and terrestrial laser scanning correlated moderately.</p> Context <p>In Western-Africa, small, unprotected forest patches amidst agricultural lands provide vital ecosystem services like carbon storage. However, accurately measuring aboveground biomass remains challenging, and terrestrial laser scanning (TLS) might become an accurate, non-destructive method.</p> Aims <p>This study explored AGB, its spatial distribution, and relationships with ecological determinants, and compared AGB estimated from manual inventory with that from TLS.</p> Methods <p>We established 109 plots and inventoried 9591 trees across seven forests in Togo, Benin, Nigeria, and Cameroon. AGB was obtained from allometric equations using diameter and tree heights, as well as from segmented point-clouds. Plot-level AGB was extrapolated to the entire forest.</p> Results <p>AGB in forest patches ranged from 85 to 259&#xa0;Mg/ha, which is lower than in nearby protected forests. Forests close to the equator have generally higher AGB, and most forests showed reduced AGB and wood density close to forest edges. AGB showed no correlation with wood density, structural complexity, and tree species richness. AGB estimations by manual inventory and TLS correlated moderately.</p> Conclusion <p>Our findings highlight the value of ground-based methods and the need to connect and protect forests as carbon reservoirs.</p>