That's true. In fact, the net oxygen production of trees (and any other plants) is exactly zero. Every atom of carbon they extract from the atmosphere (as part of CO2) and incorporate in their structure is returned to the atmosphere as CO2 when the tree rots, is burned, is eaten by termites, or whatever. Growing plants do not make any permanent net addition of oxygen to the atmosphere, or make any permanent net reduction of CO2. It's too bad the greens are ignorant of science.
The only way to use trees to permanently remove CO2 from the atmosphere is to let them grow, turn them into paper, use the paper once (no recycling), and bury the paper where the oxygen in the air can't get at it. But try telling that to the greens whose sacrament is recycling.
Use the trees for building material. Protected from the weather, walls and furniture are not breaking down into CO2.
Well yes, and for that matter coal is doing the same thing just on a longer time cycle. It’s just returning carbon to the environment after bottling it up for a while.
It’s also true that the Earth has a zero net change in carbon, as a whole. There’s never more or less of any element on earth. It just moves from one place to another.