Ecosystem carbon storage (vegetation and soil), net primary productivity (NPP), and annual net carbon sequestration (ANCS) in a natural white birch (Betula platyphylla) secondary forest in the Zhangguangcai Mountains of China were measured using relative growth equations and the carbon/nitrogen analytical approach. Measurements were taken at seven sites, including the top, middle, and lower regions of both the sunlit and shaded slope, and the valley floor. Our goal was to determine the effect of site type on ecosystem carbon stock and carbon sequestration capacity of white birch forests. Carbon storage in the vegetation of the forest ((76.28 ± 18.11)-(115.57 ± 5.59) t C/hm²) was significantly higher (35.1%-51.5%) in the upper and lower regions of the sunlit and shaded slope than in the valley (P<0.05). Vegetative carbon stores were also higher (32.5%-33.6%) in the mid region of the sunlit and shaded sloped than in the valley, but the differences were not significant (P > 0.05), Soil organic carbon stores ((81.53 ± 6.15)-(181.90 ± 21.62) t C/hm²) were significantly higher (P<0.05; 24.0%-123.1%) at the upper, mid and lower region of the sunlit slope than at the mid and lower region of the shaded slope and in the valley. (Soil organ carbon was also significantly higher (36.0%-81.2%) at the upper and mid region than at the lower region of the shaded slope and the valley (P<0.05). Ecosystem carbon storage ((174.57 ± 20.27)-(282.96 ± 17.92) t C hm^-2) was significantly higher (P<0.0514.1%-62.1%) at the three sites on the sunlit slope than at the mid and lower region of the shaded slope and in the valley, and significantly higher (19.5%-48.1%) at the upper and mid region than at the lower region of the shaded slope and in the valley (P<0.05). The NPP ((6.98±1.60)-(9.59±0.69) t hm^-2 a^-1) was the highest at the upper regions of the sunlit and shaded slopes, which were significantly higher (P<0.05; 34.2%-37.4%) than that at the mid region of the shaded slope. NPP was at a medium level at the other four sites, which were higher (8.5%-20.6%) than at the mid region of the shaded slope, where the value was the lowest. The ANCS ((3.26±0.74)-(4.56±0.36) t C hm^-2 a^-1) was the highest at the upper part of the sunlit slope, which was significantly higher (39.9%) than at the mid region of the shaded slope (P<0.05). ANCS was at a medium level at the five remaining sites, being higher (9.2%-30.4%) than at the mid region of the shaded slope, which had the lowest value. Therefore, the carbon storage, NPP, and ANCS in a temperate white birch forest ecosystem exhibited variations among sites. The effects of site type should be considered in the evaluation and management of carbon sinks in temperate white birch forests.