Mature trees sequester very little CO2. They're not growing anymore, so they have no need to suck in huge amounts of CO2 to turn into bark and leaves and twigs and things.
The best land based plants for sucking up CO2 are grass, followed by young trees.
So if we want to reduce the amount of CO2 in the atmosphere, we should chop down and bury all the old growth forests, and replace them with grass land.
Preferably grass land covered in cattle (my preference). Tasty cattle.....
So you could say that the continued clearing of the Amazon rain forest for cattle grazing is in fact a good thing as far as CO2 reduction is concerned.
Tell that to a greenie, and watch their head explode.