What is a tree worth?

It has been estimated a medium size tree produces about $30,000 worth of oxygen over 'a period of 50 years.  The other factors; soil fertility $30,000; recycling of water and controlling humidity $36,000 sheltering birds, animals, other plants etc. $30,000, and controlling air pollution $60,000. This gives a total for the 50 years of $188,000. [...]