Carbon is fungible, so trees will consume carbon emitted by any source. So in equilibrium the carbon consumed by trees and other sources will be equal to carbon emitted by decaying trees, or wildfires, or any other source, whether man made, or coming from a comet or volcano. To the trees, it's all food.
But outside equilibrium, the forest canopy will expand until equilibrium is reached, or the forest canopy will shrink until equilibrium is reached. You will also see more hungry plant life supported in environments with more carbon again until starvation levels are reached.
It is like any other kind of food. We can think of food as sequestered in the living bodies of a population, with deaths matched by births, a constant amount is sequestered. But increase food and population goes up until starvation levels are reached and now more is sequestered. Decrease food and population falls so less is sequestered. It doesn't matter where the food comes from. Currently 20% of the earth's carbon is sequestered in plant biomass. This is why various carbon offset programs do include increasing forests as a legitimate offset, but the land has to be allocated to the forest in perpetuity. It's not like you can grow 10 trees, the point is to support a bigger forest where there are 10 more trees permanently.
Thus nature regulates carbon levels at those altitudes that trees can feed from. I have no knowledge about equilibrating mechanisms in the atmosphere as a whole, this discussion is for carbon accessible to plants.
But outside equilibrium, the forest canopy will expand until equilibrium is reached, or the forest canopy will shrink until equilibrium is reached. You will also see more hungry plant life supported in environments with more carbon again until starvation levels are reached.
It is like any other kind of food. We can think of food as sequestered in the living bodies of a population, with deaths matched by births, a constant amount is sequestered. But increase food and population goes up until starvation levels are reached and now more is sequestered. Decrease food and population falls so less is sequestered. It doesn't matter where the food comes from. Currently 20% of the earth's carbon is sequestered in plant biomass. This is why various carbon offset programs do include increasing forests as a legitimate offset, but the land has to be allocated to the forest in perpetuity. It's not like you can grow 10 trees, the point is to support a bigger forest where there are 10 more trees permanently.
Thus nature regulates carbon levels at those altitudes that trees can feed from. I have no knowledge about equilibrating mechanisms in the atmosphere as a whole, this discussion is for carbon accessible to plants.