The pastoral livestock system is criticized for its environmental impact caused by high greenhouse gas emissions per unit of product, and the adverse effects on soil and vegetation. In Senegal, the carbon stock in vegetation has been monitored by the Center for Ecological Monitoring at 24 sites in the Sahel since 1987. However, soil C stock, an essential parameter for the humification process of tree litter and rhizodeposition of grasses, is not taken into account. This study aimed to determine the influence of tree and environmental factors on soil C content. Thus, 15 of the sites monitored in the Center were selected, and 480 soil samples were collected at 0–10 cm and 10–30 cm depth under and outside the tree crown. Total C and N contents were predicted by near-infrared spectroscopy (NIRS), and C and N stocks were calculated from 60 soil samples taken from under and outside the tree crown. A principal component analysis was carried out to identify the factors involved in C stock variation. Thus, in the sylvopastoral area of Senegal, these stocks varied along a north-south gradient; they were positively correlated with rainfall, tree cover, and biomass. They varied between 9.3 and 29.7 Mg C/ha at 10–30 cm. At a finer scale, the tree induced an increase in C and N contents under the crown in the 0–10 cm layer. This study showed that soil C stocks can be used to determine the need for C compensation in Sahel through tree planting. ; El sistema de ganadería pastoral es criticado por su impacto ambiental debido a las elevadas emisiones de gases de efecto invernadero por unidad de producto y por su efecto adverso sobre el suelo y la vegetación. En Senegal, el Centro de Seguimiento Ecológico lleva a cabo un seguimiento del carbono almacenado en la vegetación en 24 zonas del Sahel desde 1987. Sin embargo, no se tiene en cuenta el almacenaje de C en el suelo, un parámetro esencial en los procesos de humificación de la hojarasca de los árboles y la rizodeposición de las plantas herbáceas. Este estudio tenía como ...