A substantial portion of the carbon (C) emitted by human activity is apparently being stored in forest ecosystems in the Northern Hemisphere, but the magnitude and cause are not precisely understood. The goal of these studies was to directly track changes in forest C using repeated inventory measurements of nonfederal lands in Oregon, and of national forests in Oregon and Washington. Although net area of forestland increased in Oregon, the net effect of land-use change on C was a decrease because forest gains in low-C juniper forests were offset by losses in high-C Douglas-fir forests. On nonfederal lands, C decreased significantly in eastern Oregon due to the effect of western spruce budworm, but increased significantly in western Oregon due to growth on nonfederal public lands. On national forest lands, C increases were higher on the west side of the Cascades, and primarily stayed in the live tree pool, compared to lower increases on the east side, where most of the increase was seen in the down wood pool. Fire led to decreased C stores in wilderness areas east of the Cascade Range. The small impact of recent fires on carbon storage in national forests suggests fires may not be a cause for concern, although investigation of longer term effects is warranted. Better understanding of the magnitude of effects of land-use change, management, and disturbance on carbon storage from repeated inventory measurements will improve our ability to predict the effects of future changes in those drivers.