Revised historic harvest data improve estimates of the impacts of human activities on reported greenhouse gas emissions and removals in Canada's managed forest.

Guidelines for international reporting of greenhouse gas emissions and removals in the forest sector require a land-based approach that includes all lands subject to forest management activities such as harvest, forest inventory, regeneration, management of natural disturbances, and protected areas. The reported net greenhouse gas balance of managed forests is not limited to forest stands resulting from timber harvest and wood product use. Reporting guidelines specify methods to reduce interannual variability in reported emissions attributable to natural disturbances. In Canada, the initial (1990) assignment of all inventoried stands to anthropogenic or natural disturbance reporting categories is determined by the last stand-initiating disturbance. A new compilation of historic (1889 to 1989) harvest data in Canada reduces the area reported in the anthropogenic category by 34 million hectares (20%) in 1990. This area transfer from anthropogenic to natural origin reduces the carbon sink reported as anthropogenic by 113 Mt CO2e yr−1 (56%) in 1990 and by 30 Mt CO2e yr−1 (23%) in 2021. [ABSTRACT FROM AUTHOR]