This report on the forest ecosystems of 31 predominantly forested national parks is the first in the Carbon Atlas series. Parks Canada has undertaken the development of a series of Carbon Atlases as part of an effort to create a more comprehensive picture of the amount and density of carbon stored in park ecosystems (i.e., carbon stocks), amount of carbon transfers between various pools (i.e., carbon fluxes), and how carbon storage and fluxes have been changing over time. The objective of the Carbon Atlas project is to estimate and spatially map the carbon balance in all major ecosystems in Canada’s national parks and national marine conservation areas.