If you kill one tree how much oxygen are you killing?

All trees with green leaves (ie. that have chlorophyl in them) give out oxygen in the day during photosynthesis. Note: They don't actually make the oxygen. It already exists. Two atoms of oxygen are bonded with a carbon atom to make the carbon dioxide molecule which animals breathe out. Trees and plants breathe it in, keep the carbon for themselves, and breathe out the oxygen.