How do trees recycle oxygen?

Trees don't actually "recycle" oxygen. Oxygen is a waste product of photosynthesis. Plants use water and carbon dioxide to produce sugar (glucose). Oxygen is actually a waste product. Just look up photosynthesis and you can get a very in depth explanation of the process. Trees don't actually "recycle" oxygen. Oxygen is a waste product of photosynthesis. Plants use water and carbon dioxide to produce sugar (glucose). Oxygen is actually a waste product. Just look up photosynthesis and you can get a very in depth explanation of the process.