Contribution of Neglected Carbon Pools to Carbon Storage in the Humid Tropical Forests of Eastern Cameroon

Abstract

In the tropical forests of the Congo Basin, the understory constitutes a forest stratum whose components are generally neglected in studies related to forest carbon storage, despite their contribution to climate change mitigation. The objective of this study is to estimate the carbon stocks of understory components (herbaceous plants, understory woody species, litter, and fine roots) in semi-deciduous forests of eastern Cameroon. Carbon stock estimation was carried out using a destructive sampling approach. Data on woody species with a diameter ≤10 cm were collected in 14 randomised plots of 20 m × 20 m (400 m²). Data on woody species with a diameter ≤4.99 cm, herbaceous plants, litter, and fine roots were collected in subplots of 10 m×10 m, 1 m×1 m, 0.5 m×0.5 m, and 0.2 m×0.2 m, respectively. Diameter and height of woody species were measured. The understory, composed of the four carbon pools mentioned above, stores 11.92 ± 2.15 tC/ha, of which 47% is contributed by fine roots, 26% by woody species, 25% by litter, and 2% by herbaceous plants. A significant difference was found among carbon stocks across the different pools considered. Carbon stocks across diameter and height classes followed a bell-shaped distribution, with peaks in the 2.5–7.5 cm diameter classes and the [4–8 m] height classes. Given these substantial quantities, it is essential to reconsider the role of the understory in carbon accounting, particularly to optimise REDD+ programs and enhance the resilience of Cameroonian forest ecosystems to climate change.