Little information exists regarding the effects of intermediate stand management activities (e.g., thinning) on C storage. This lack of information has created uncertainty regarding trade-offs between the benefits observed following thinning and C storage. Using long-term growth data, this study examines the effect of thinning on C storage while controlling for the effects of site quality in yellow-poplar (Liriodendron tulipifera L.) forests throughout the southern Appalachian Mountains. In 1960, one hundred and eighteen 0.1 ha plots were established in yellow-poplar forests throughout the southern Appalachians and subsequently thinned to a randomly assigned residual basal area (RBA) (square metres per hectare). Carbon storage increased through time across all levels of RBA. RBA had a long-term effect on C storage with greater C storage occurring at greater RBA. On average-quality sites, thinning to 30 m2ha–1 stored 84% more C than thinning to 10 m2ha–1. At no time did plots with progressively lower RBA store more C than plots with progressively higher RBA. The results from this study provide information about the effects of intermediate silvicultural disturbance on C dynamics of the aboveground live tree pool in a complex landscape and may be used to inform decisions regarding trade-offs between active management and C storage.