18000 



15000 



d 12000 



M 9000 



6000 



3000 



MGMT 



000 

 POO 



PCB 

 PCI 

 PCA 



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



AGE 



Figure 19 — Effect of tfiinning on standing volume of Douglas-fir plantations (total 

 cubic feet), site index 90. 



25000 - 



20000 - 



15000 



10000 - 



5000 



MGMT 



000 

 POO 



PCB 



PCI 

 PCA 



Figure 20— Effect of thinning on standing volume of Douglas-fir plantations 

 (merchantable board feet [Scribner]), site index 50. 



20 



