Changes in forest vegetation composition can lead to changes in carbon stocks. The aim of this study is to identify the relationships between diversity attributes, structural parameters and aboveground carbon stock within vegetation units in the Péni Classified Forest. In total, 3225 individuals belonging to 212 woody species were measured. Our results show a variability of carbon stock between vegetation units ranging from 2.56±2.31 t.ha-1 in shrub savannas to 131.80±75.45 t.ha-1 in gallery forests. Allometric models of structural parameters alone govern the variation of carbon stock between vegetation units. In gallery forests, Gmelina plantations and tree savannas, basal area explained 95%, 95% and 92% of the variation in carbon stock, respectively. In shrub savannas, the model combining mean diameter, basal area and mean height, explained 92% of the variation in carbon stock. The consideration of models combining diversity attributes and structure parameters is therefore necessary for a good estimation of the carbon stock of forest ecosystems.