The carbon (C) pools of aboveground tree components (leaf, stem, branch, and stem bark), ground cover, organic, and mineral soil were examined and compared with three stand development stages based on the mean tree diameters [diameter at breast height (dbh) in which small-diameter forests (SDF) = 0-8 cm, medium-diameter forests (MDF) = 8-20 cm, and large-diameter forests (LDF) = 20-36 cm] in pure coppice-originated oak stands located in the northwestern Turkey. In tree components, only the stem C concentration differed significantly among the development stages. The total C pools of the total tree biomass changed between 13 and 89 Mg ha(-1) from SDF to LDF. The C content of tree biomass was strongly correlated with dbh (R (2) = 0.83). The C contents of the ground cover differed significantly while the C contents in both organic soil layers were also markedly different and increased from SDF to LDF. The amount of C stored in the soil pedon was 84, 123, and 103 Mg ha(-1), and the total ecosystem (without belowground tree parts) C pools were 97, 177, and 192 Mg ha(-1), for the SDF, MDF, and LDF, respectively. Total ecosystem C content was significantly correlated (R (2) = 0.46) with dbh despite soil pedon C showed very weak correlation. The ratio between the C pool of the total aboveground tree components and total ecosystem C was 13 % in the SDF, 30 % in the MDF, and 46 % in the LDF. These results show that the soil was the main pool of C in the forests for all of the development stages.