30000 - 



25000 



M 20000 - 



15000 - 



10000 - 



5000 ■ 



MGMT 



PCA 

 PCI 

 PCB 

 POO 

 000 



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



AGE 



Figure 47 — Effect of tfiinning on total yield of grand fir plantations (total cubic feet), 

 site index 90. 



66000 



55000 



d 44000 - 



> 

 u. 

 ffl 



-! 33000 



22000 



11000 



MGMT 



000 

 POO 



PCB 



PCI 

 PCA 



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



AGE 



Figure 48 — Effect of thinning on total yield of grand fir plantations (merchantable 

 board feet [Scribner]), site index 50. 



39 



