Re: Does a tree use as much CO2 when living as produced while decaying?

This question is basically asking whether or not everything decomposes 
completely.  The answer to this question is "It depends!"
If everything decomposed completely we would have no fossil fuels, among 
other things.  On the other hand if nothing decomposed all the carbon and 
many other nutrients would be locked up in dead organic matter and life 
would cease to exist!
It is possible to find buried logs that are thousands of years old, and 
soild organic matter has been dated to tens of thousands of years. Using 
this information, youmay be able to approach the answer to your question. A 
recent article in the journal Science may shed light on this.

Carbon Sequestration in Soils, by 

      William H. Schlesinger

      Science 1999 June 25; 284: 2095