Expert: Walter Hintz - 3/8/2011

Question
QUESTION: Could you please tell me how much oxygen is produced by a tree? I want to also know how many trees are needed to feed us oxygen?

ANSWER: I can't give you  numbers John because it depends upon the type of tree, the size of the tree and environmental factors

---------- FOLLOW-UP ----------

QUESTION: I wanted to find out the output of oxygen during photosynthesis. I am aware that different trees will produce different amounts of oxygen depending on the environment. My concearn is that some trees may actually consume more than they produce - it may be appropriate to harvest these trees to meet our needs and not the trees that offer a beter environmental return to us.

Answer
The problem is that the photosynthetic rate depends upon the amount of light and CO2. WE have to consider the total oxygen out put from trees rather then how much is produced be a single tree. The fact is that most of our oxygen (up to 70 %) is produced by phytoplankton and not trees. The Ocean is our main source of O2.