While I do not wish to
undermine this brilliant writeup, there is another, rather
major factor to consider.
When plants die and
decompose, the decomposition process uses about as much
oxygen as the plant releases during its
lifetime. Therefore, one would need to ensure that any plants '
on the brink' were removed* before they began to decompose.
This is why
de-forestation does not directly harm our air source (don't get me wrong, it is a very bad thing though). Almost all our air is processed by
single cell organisms living in the ocean and so forth.
*
nebuchadnezzar suggests that they might be eaten by the occupant.