The equations presented in this report can be used to estimate site index and/or 

 yield capability for each of the following species: 



1. Western white pine ( Pinus monticola Dougl.) 



2. Ponderosa pine ( Pinus ponderosa Laws.) 



3. Lodgepole pine ( Pinus contorta var. latifolia S. Wats.) 

 ■ 4. Western larch ( Larix occidentalis Nutt.) 



5. Engelmann spruce ( Picea engelmannii Parry) 



6. Inland Douglas-fir ( Pseudotsuga menziesii var. glauca 



(Mirb.) Franco) 



7. Grand fir ( Abies grandis (Dougl.) Lindl.) 



8. Quaking aspen ( Populus tremuloides Michx.) 



For western white, ponderosa, and lodgepole pines, and for western larch and 

 grand fir, the yield capabilities that are supposed to be equivalent to given levels 

 of site index are shown in table 1. For Engelmann spruce, inland Douglas-fir, or 

 quaking aspen, yield capability equations cannot be given because the necessary informa- 

 tion was not available. 



Table 1. -- Yield capability according to site index for western white pine , 

 ponderosa pine, lodgepole pine, western larch, and grand fir 



Site index Yield capability 



(50-year Western . Ponderosa Lodgepole Western Grand 



base age) white pine^ pine^ pine^ larch^ f ir - 



Cubic feet per acre per year 



20 



49. 



.5 



19. 



,4 



12, 



.4 







56, 



.5 



25 



58. 



. 1 



24. 



.2 



16, 



.4 







65, 



.2 



30 



66, 



.8 



29. 



.6 



21, 



.6 



21 , 



.8 



73, 



.9 



35 



75. 



,4 



35. 



,5 



27, 



,8 



26, 



.7 



82, 



.6 



40 



84. 



, 1 



42. 



,1 



35, 



.1 



33, 



.8 



91, 



.3 



45 



92. 



.7 



49, 



.6 



43, 



.5 



42, 



.5 



100, 



.0 



50 



101. 



,4 



57. 



,9 



53, 



.0 



52, 



,2 



108, 



.7 



55 



110. 



, 1 



67. 



.3 



63, 



.6 



62, 



.7 



117, 



.4 



60 



118. 



, 7 



77. 



.9 



75, 



.3 



73. 



,8 



126, 



.1 



65 



127. 



,4 



89. 



,9 



88, 



.0 



85, 



.3 



134, 



.8 



70 



136. 



.0 



103. 



,4 



101, 



.8 



97, 



,2 



143, 



.5 



75 



144. 



.7 



118, 



,7 



116, 



.8 



109. 



.3 



152, 



.2 



80 



153. 



.3 



136. 



.1 



132, 



.7 



121. 



,7 



160, 



.9 



■i'Based on all surviving trees in the stand at the age of culmination of cubic 

 mean annual increment. 



^Based on all trees larger than 5.0 inches d.b.h. 



