



















LODGEPOLE PINE 



















































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10 20 30 40 50 60 70 80 



Site index (height in feet at 50 years) 



Figure 6. — Relationship between site index and yield aapability. 



Yield Capability 



The equation for lodgepole pine was obtained by projecting yields of hypothetical 

 stands according to the method published by Myers (9). The projection procedure dif- 

 fered from that of Myers in that we maintained a different stocking level for each 

 level of site index. Myers used stocking levels of 80 for poorer sites and 100 for 

 better sites. By 80 and 100 are meant stocking regimes that bring the stand to 80 or 

 100 square feet per acre of basal area at the time when average^ stand diameter at 

 breast height (d.b.h.) is 10 inches. Thereafter the stocking level is kept by thinning 

 at 80 or 100 square feet of basal area per acre, even though average stand d.b.h. will 

 increase. In making stand projections to derive a yield capability equation, the 

 levels of stocking used for each site index were a linear function of site index, as 

 shown below. 



Site index at a 

 50-year base age 



20 

 30 

 40 



60 

 70 

 80 



Stocking level 



74.0 



84.5 



94.8 

 105.0 

 115.2 

 125.7 

 136.0 



The d.b.h. of the tree of average basal area. 



10 



