The paper summarizes the results of a long-term monitoring the development of a spruce monoculture established at the beginning of the 20th century on the original beech site in the region of the Drahanská vysočina upland (the Rájec project). The results are presented from the aspect of changes in the accumulation and transport processes of carbon. The whole process of changes is characterized in particular stages of the forest stand development on the studied area: (1) the conversion of original beech stand for spruce monoculture, (2) the first stage after the clear-cutting regeneration of spruce, (3) the second stage of the clearing development, (4) the stage of the spruce stand development of the 2nd generation after cleaning and leaving the stand development without silvicultural interventions. Significant changes in carbon accumulation occurred through the conversion of the species composition of the original beech stand to a spruce monoculture, deceleration of decomposition processes and accumulation of carbon in surface humus. As well the development of herb vegetation on the clear-cut area shows great importance for the biogenic elements cycle and carbon, which begins in the third year after felling.