30000 



MGMT 



POO 

 PCB- 



000 

 PCI 



RCA 



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



AGE 



Figure 41 — Effect of thiinning on standing volume of grand fir plantations (total 

 cubic feet), site index 90. 



9 44000 



cr 33000 



22000 



11000 



000 

 POO 



PCB 



PCI 

 PCA 



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



AGE 



Figure 42 — Effect of thinning on standing volume of grand fir plantations (merchant- 

 able board feet [Scribner]), site index 50. 



36 



