30 



SITE INDEX 



80 



70 



60 



50 

 40 



10 



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



AGE 



Figure 57 — Quadratic mean diameter vs. age for western larch precommercial 

 thinning to 250 trees per acre at 20 years in Inland Northwest forests. 



30 r 



20 



10 



SITE INDEX 



80 

 70 



60 



50 

 40 



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



AGE 



Figure 58 — Quadratic mean diameter vs. age for western larch precommercial 

 thinning to 250 trees per acre at 20 years and commercial thinning from below 

 to 100 trees per acre at 50 years in Inland Northwest forests. 



49 



