If you allow decomposition then obvioisly net must be zero. If you createa object and destroy it, it pretty much has to release its source material in some form.
If tree stops growing it obviously has to have zero net. Anything absorbing anything has either to store it - grow, or release it in some form. Carbon is element, what are the options? Store it permanently, transform chemically and release, or transform it atomically and change the element but tree is not a nuclear plant.
If you allow decomposition then obvioisly net must be zero. If you createa object and destroy it, it pretty much has to release its source material in some form.
If tree stops growing it obviously has to have zero net. Anything absorbing anything has either to store it - grow, or release it in some form. Carbon is element, what are the options? Store it permanently, transform chemically and release, or transform it atomically and change the element but tree is not a nuclear plant.