The Forest Ecosystem Carbon Database presented in this report was compiled to meet the data needs of large-scale modelers and analysts working with the carbon budgets and dynamics of different forest ecosystems in Canada. The accompanying compact disk provides data for over 700 plots from across Canada, and includes data for over 60 variables. A summary of estimated carbon content for soil, tree biomass by component, and total ecosystem carbon for each plot is appended to this report. These estimates do not include detrital carbon (woody debris, etc.) or root biomass, which may significantly alter estimates for total ecosystem carbon in some forest types. The preliminary analyses in this report indicate that ecozones can be grouped on the basis of low and high average total biomass carbon and that these groups correspond to ecozones with low and high average total ecosystem carbon. Within each group of ecozones, mineral soil carbon contributes the highest proportion of carbon to the average total ecosystem carbon, and it is positively correlated with a gradient in ecozone climate from cold and dry to warm and wet. Differences between ecozones for the distribution of carbon within a mineral soil profile and variability in the carbon content of soil organic horizons may be explained by site-specific characteristics, such as differences in parent material and pedogenic processes.