■° 60 

 >■ 



S 50 



!5 



m 

 a. 



3 40 

 > 30 



20 























WESTERN LARCH 





























, 







1 























1 















































































































































30 40 50 



Site index (height in feet at 50 years) 



Figure 7. — Relationship between site index and yield capability. 



Yield Capability 



The yield capability equation for western larch is based on current work being 

 done by Roe and John H. Wikstrom.-^ For cubic volume yield capability in stems 5.0 

 inches d.b.h. and larger, the equation is: 



where 



YC = bo + bi S + b2/S, 

 YC 



S = 

 bo = 

 bi = 

 b, = 



yield capability in cubic feet per acre per year 

 of mean annual increment 



site index (50-year base age) 



-126.05 



2.7974081 



1919.3157. 



This equation cannot be used when site index is less than 26 feet, because the table 

 from which it was made gives no information below site index 30. 



^Principal Economist, Intermountain Forest and Range Experiment Station, 



12 



