Biomass and soil carbon stocks of the main land use of the Allada Plateau (Southern Benin)

The inventory of the carbon (C) pools in Africa's ecosystems is not well documented, although it is crucial to support climate mitigation policies. We quantified the C stocks in plant biomass, woody necromass, litter and soil (0-30 and 30-100 cm) for the five main land uses - forest, tree plantation, young and adult palm groves, croplands - of Ferralsols on the Allada plateau in southeast Benin. Forests have the highest total C stocks (389 +/- 54 Mg C ha(-1)) compared with other land uses (222 +/- 33, 154 +/- 6, 105 +/- 2, 77 +/- 3 Mg C ha(-1) in tree plantations, adult palm groves, young palm groves and croplands, respectively). The C stocks are higher in the biomass than in the soil (0-100 cm), e.g. in the forest, stocks were 279 +/- 54 Mg C ha(-1) in the biomass versus 83 +/- 2 Mg C ha(-1) in the soil. Differences of soil C stocks between land uses are low (approximate to 28 Mg C ha(-1)) and concentrated in topsoils. The structure and species diversity of the forest partly explained the variability and the high C biomass compared to tree plantations. Type of forest and plantations is important to consider in conserving C stocks in landscapes.