What effect would over logging of trees have on the amount of carbon dioxide in the atmosphere

Well,
Trees are essential to the ecosystem, for many things. Living tree leaves, which means they are on the tree, take in carbon dioxide and excrete oxegyn. Similar to how we breathe in oxegyn and exhale carbon dioxide, trees do the opposite. The less trees, the more oxegyn. If you think about it, the less people, the more oxegyn.

It shows that the experiment is designed properly.