Species-specific wood density improves biomass estimation in Congo Basin peatland forests

The central Congo Basin hosts the world's largest tropical peat swamp forest (PSF), covering 167 600 km² and storing approximately 29 Pg of carbon below ground. However, estimates of above ground biomass (AGB) remain limited, partly owing to reliance on global wood density (WD) databases that may not reflect local species characteristics. This study assessed the impact of species-specific WD on AGB estimation in five PSF sites of the northern Republic of Congo. Specific WD was collected in one site, and these data were then used to estimate AGB in four additional sites. We collected wood cores using an increment borer from 244 trees to measure the WD of the 20 most abundant species (93% of trees with diameters ≥10 cm). Using global WD values overestimated AGB by 24.7% (p < 0.05). The low average local WD (0.460 ± 0.12 g cm-3) explained this difference. The WD variation was primarily species-driven (58%) and associated with functional traits; pioneer and evergreen species had lower WD. These findings highlight the importance of locally measured WD for accurate biomass and carbon stock estimation in tropical peatland forests. A French translation of this abstract is available in the supplementary material. This article is part of the discussion meeting issue 'African tropical peatlands: function, value and vulnerability'.