Abstract Forest management affects stand age. In consideration of the strong link between stand age and carbon cycling, altering harvesting regimes can influence regional carbon stocks and sequestration. Recent research has quantified ecosystem carbon stocks across stand age in upland conifer and aspen–birch forests of the northern Lake States. This study applied those relationships to assess how forest management could influence carbon stocks in these two forest types. US Forest Service Forest Inventory and Analysis data were used to estimate current regional age structure and management intensity and state Gap Analysis Program data were used to assess forest type abundance. Across the region, current carbon stocks in aspen–birch and upland conifer forests are estimated to be 590 and 367 Tg C, respectively. Ceasing timber harvesting over the next century would increase the prevalence of older stands and increase ecosystem carbon stocks by 54% (31% in 50 years) and 30% (19% in 50 years) in aspen–birch and upland conifer forests, respectively. Harvesting aspen–birch stands would change ecosystem carbon stocks by +4% or −13% under annual harvesting of 1 or 2%, respectively. Harvesting upland conifer stands at a rate of 1 or 2% every year would decrease ecosystem carbon by 3 and 18%, respectively. Carbon from harvested material partly compensates for differences in total carbon stocks between no-harvest and harvest scenarios, suggesting a net positive carbon sequestration in all scenarios within 100 years. These results provide insight into the potential maximum impact of forest management on carbon stocks and sequestration in these two forest types.