My understanding is that if you create a new forest, the amount of carbon needed to create it is taken from the atmosphere. Even if trees in the forest die and decompose, the forest will on average consist of carbon which previously was part of the atmosphere, in effect removing carbon from the atmosphere.
Yes. Planting a forest is a one-off, though. The only way to capture more carbon with the same land is to cut down all the trees, bury them deep enough so that they don't decompose, and start again.
