The following study examines the content and composition of soil organic carbon (SOC), focusing on the fractions of humic and fulvic acids under different vegetation types in Ruy Mountain, located in SW Bulgaria. Soil samples from surface horizons (0–10 cm) were analyzed to determine the total carbon, organic carbon, and the ratio of humic to fulvic acids. Results show significant variation in SOC, with the highest levels in soil under Fagus sylvatica (beech) forests and the lowest under Pinus sylvestris (pine) forests. The humic to fulvic acid ratio suggests that soils under beech forests have a higher humification degree. The study highlights the influence of vegetation on SOC composition and the importance of conserving natural vegetation for soil health and carbon sequestration.