For large areas of degraded shrubland and substantially reduced lands for forest, vegetation restoration can be applied to convert degraded shrubland to tree forest (CST) in areas favorable for planting trees. Understanding the effects of CST on ecosystem carbon storage and its components can facilitate afforestation/reforestation efforts and forest carbon sequestration programs in China. In this study, we assessed larch (Larix principis-rupprechtii Mayr., LPR) plantations of different ages (10, 18, 23, 27 and 35-year old), which were previously degraded shrubland, and adjacent degraded shrubland in the Guandi Mountain Forest Region, northern China, to explore the effects of CST on ecosystem carbon storage and its components. Compared with that of the adjacent shrubland, ecosystem carbon storage and its components were lower at the early stages of afforestation. The ecosystem carbon storage of the 10-year-old LPR plantations was significantly lower (32.9%, P < 0.05) than that of the shrubland; however, not all differences between carbon pools were significant (P < 0.05). Total vegetation carbon storage was 34.7% lower in the 10-year-old LPR plantations than in the adjacent shrubland, and above-and belowground carbon pools were 5.4% and 70.9% lower, respectively; however, only the difference in the belowground carbon pool was significant (P < 0.05). The litter carbon storage was 42.8% lower (P=0.71), soil organic carbon storage (0-50 cm) was significantly lower (32.6%), and carbon storage in the different soil layers (0-10, 10-30, and 30-50 cm) was also significantly lower (P < 0.05) in the 10-year-old plantations compared with the adjacent shrubland. The ecosystem carbon storage of LPR was 1.6 times higher in the 35-year-old plantations than in the 10-year-old plantations, and the carbon storages of the vegetation (aboveground, belowground, and whole), litter, and soil organic carbon (soil layers and whole) were also higher in the older plantations. Therefore, the ecosystem carbon storage (and its components) of LPR plantations gradually reached and surpassed that of the degraded shrubland. However, the process to reach the carbon storage levels of shrubland occurred over different time periods:soil organic carbon pool > vegetation belowground pool > vegetation aboveground pool, where deep soil organic carbon > surface soil (0-10 cm).