tree question

[rocklock]

1. what is hemfir?
2. In the span tables is there a difference between Douglas fir and Northern White fir?
3. What about Hemlock and the span tables...
A friend used white fir and treated it all the same... now he shows the log of white fir is different...
4. Should all the trees be the same?
Thanks

[RockEngineer]

Here is a link to your definition for Hem-Fir. Links to the timber grading organizations can answer many of your questions.
http://www.wwpa.org/hemfir.htm