Comment by GhostVII

I don't think this should be too surprising. Forests don't destroy carbon, just store it in the form of trees. When the trees decompose, or burn down, it is released again. So for a mature forest you would expect it to have around net 0 emissions. As far as I know the main way a forest can be a carbon sink is if it is expanding, which I don't think Canada's forests are doing.