15000 r 



12000 



6000 



3000 



10 



20 



+ 



++ + 



30 



40 



50 60 

 SITE INDEX 



70 



80 



Figure 11 — Douglas-fir yield vs. site index at 70 years of age (total 

 cubic feet). 



90 



100 



SITE INDEX 



100 



90 

 80 



70 

 60 



50 

 40 



10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 



AGE 



Figure 12 — Quadratic mean diameter vs. age for Douglas-fir unthinned plantations 

 in Inland Northwest forests. 



16 



