Geological Influence on Selected Soil Physicochemical Properties and Carbon-Nitrogen Stocks in Granito-Gneissic Basement and Sedimentary Basins of Gabon

Abstract

Gabon, with nearly 22 million ha of forest, is the second most forested country in Africa and part of the Congo Basin. Its diverse geology affects soil functioning. This study assessed soil organic carbon (SOC), total nitrogen (TN) and carbon dioxide equivalent (CO₂eq) in rainforest soils from the granito-gneissic basement and coastal sedimentary basin of Gabon at depths of 0–30 cm. Bulk density, sand, clay, SOC (115.33 Mg C ha⁻¹), TN (9.83 Mg N ha⁻¹) and CO₂eq (417.52 Mg CO₂ ha⁻¹) were higher in the granito-gneissic basement, whereas pH and silt (33.3 %) were greater in the sedimentary basin. Despite very sensitive variabilities, the results present good evidence indicating a strong influence of lithology and vegetation cover on soil texture and nutrient richness. This study has identified for the first time the key elements to consider for sustainable soil carbon management.