Tree & roots are a fractal transport system, trapping carbon (black), releasing oxygen (red). When carbon dioxide (CO2 black and red) touches leaves it is used in oxygenic photosynthesis. Oxygen (O2, red) emanates from the leaves. Carbon (black travels downwards and is sequestered in roots and soil. Of course much carbon is used in making plant sugars. Some carbon also travels down with the leaves that turn yellow and fall, but much of that carbon is later released as CO2.
