What percentage of carbon in trees comes from CO2 in atmosphere ?

Question

Just trying to get a better picture how much CO2 is absorbed by trees and plants. I think most most come from the soil ?

Answer 1

All the carbon in plants comes from the air.

The carbon in soil is in the form of rotting plant and animal material which cannot be used directly by plants and is broken down by microorganisms to release carbon dioxide into the air.

The roots of a plant absorb a tiny amount of carbon dioxide from the little air spaces around them but I think that still counts as air or atmosphere. It's carbon in a gaseous form anyway. No solid, liquid or aqueous carbon is absorbed by roots.

Answer 2

No. All of the carbon that is incorporated into plants (or at least the vast, vast majority) comes from atmospheric CO2. The soil provides water and minerals, but not much else.