Effective forest carbon (C) management requires an understanding of how stand-replacing disturbances affect C pools and fluxes over successional timescales, and how the growth of secondary forests compares with that of undisturbed forests. In the upper Great Lakes region, fires that followed clear-cut harvesting shaped a century-old cohort of secondary forests, but the long-term effects of fire on C cycling in this relatively fire-averse landscape remain poorly understood. We examined how two different stand-replacing disturbances – one with and the other without fire – influenced C pools and fluxes through a century of stand development, comparing secondary aspen-dominated (Populus) forests with legacy late successional stands encompassing the ages and species compositions that would be prevalent today in the absence of stand replacement. Our work at the University of Michigan Biological Station (UMBS) used experimental forest chronosequences established following clear-cut harvesting or clear-cut harvesting followed by fire, along with three > 130-yr-old late successional deciduous broadleaf (DBF), evergreen needleleaf (ENF), and mixed (MIX) forest functional types. The successional trajectories and values of total (above- and belowground) ecosystem C mass, net primary production (NPP), and net ecosystem production (NEP) were similar regardless of whether fires occurred following clear-cut harvesting. Moreover, 80 + year old secondary forests’ C pools and fluxes were comparable to late successional ENF and MIX, but were at times lower than DBF. While the century-old secondary forests and legacy stands served as consistent C sinks over the last century, more extreme temperatures in recent years may be eroding NEP by accelerating C losses from soils. We conclude that the compounding effects of fire and clear-cut harvesting were similar to those from clear-cut harvesting alone, possibly because of the disturbance-adapted properties of pioneer species, most notably aspen; however, our results also suggest that changing climate rather than prior disturbance may jeopardize the future of this long-term terrestrial C sink.