Estimation of biomass and carbon stock along an altitudinal gradient in the forests of the Western Highlands Cameroon: case of Western slope of the Bamboutos Mountains

Controlling the quantities of biomass and carbon contained in Cameroon’s tropical forests is an asset for the successful implementation of climate change mitigation strategies. The aim of this study was to assess the biomass and carbon stored by the forests along the western slopes of the Bamboutos Mountains and to examine whether altitude has an influence on basal area, stem density, wood density and biomass values. Inventory data from 18 plots of 0.5 hectare each, established in mid-altitude and submontane forests were used. Biomasses were obtained using the non-destructive method. Estimates of above-ground biomass using trunk diameter, height and wood density gave a mean value of 155.49±57.54 t. ha-1; 292.28±90.81 t. ha-1, compared with 150.49±42.16 t. ha-1, 165.62±45.74 when height was excluded in mid-altitude and submontane forests respectively. The comparison test showed that there was no significant difference in these biomass values. PCA showed a positive relationship between altitude and these three variables (stem density, basal area and biomass). The large-tree diameter class (≥ 70 cm) contributed 41% to biomass accumulation in the submontane forest compared with 22.9% in the mid-altitude forest. Napoleonaea egertonii and Santiria trimeria showed the highest biomass values in the mid-altitude and submontane forest respectively, revealing that biomass varies according to species and depends on the size and abundance of the species concerned. This study showed that height made little contribution to biomass accumulation and that the quantities of certain structural parameters increased with altitude. The results of this study highlight the role played by the forests of the Bamboutos Mountains in climate regulation.