Fraction Cull in Sorihner Board Foot Volume Given the Tree Is Unsound — Unforked and 

 Forked Trees 



The following model form is used to predict the fraction of an unsound tree's 

 Scribner board foot volume that is cull: 



FC3 = h^ie^) 



where 



FCg = Predicted fraction cull in Scribner board foot volume to a 6- inch top given 

 the tree is unsound 



= A constant 



= A function of the tree's attributes. 



The appropriate values of and functions for Y^, respectively, the number of trees 



used, and the resulting RMSQR values are found in table 16. Again, the models for 

 Engelmann spruce and corkbark fir were too poor to be useful and, therefore, only their 

 mean FC^ values are included. Several other models proved to be no better than the mean 

 so the user may also want to use the mean FC^ values in table 16 rather than the models. 



Methodological details can be found in appendix XV. 



Table 16. — Fraation cull in Scribner board foot volume, given the tree 

 is unsound, data base, and regression results 



D.b.h. 



Independent variables 

 in inches H = Total tree height in feet 



Species, National Forest, and regression results 



Mean 

 FC_ 



Number 

 of 

 trees 



Relative 

 mean squared 

 residual 

 (RMSQR) 



White pine on Santa Fe, Carson, and Lincoln 

 = 0.245464500 



= 9.55078847E-04(D') 



Engelmann spruce on Santa Fe, Carson, and Lincoln 

 No model — Use mean FC 



S 



Corkbark fir on Santa Fe and Carson 

 No model — Use mean FC^ 



Yellow pine on Santa Fe, Carson, Lincoln, Coconino, and Tonto 

 = 1.38266375 



Yg = -1.94422273E-02 (H) 



Blackjack pine on Lincoln, Coconino, and Tonto 

 = 0.617372520 



Yg = -1.96681561E-02 (H) 



Blackjack pine on Santa Fe and Carson 

 = 0.646540139 



Y^ = -2.20260760E-01(H/D) 



Douglas-fir on Santa Fe, Carson, Lincoln, and Tonto 

 = 1.24325723 



-3.45196887E-01(H/D) 



Aspen on Santa Fe and Carson 

 = 1.23056500 



Y^ = -5.46784441E-03 (H) 



White fir on Santa Fe, Carson, and Lincoln 

 = 0.294076429 



Y^ = 4.60611418E-06(D^H) 



0.41683 



.42864 



.57057 



.36288 



.20529 



,27296 



.31653 



.93059 



.39036 



39 

 45 

 21 



202 



138 



114 



116 



114 



62 



1.0027 



.9028 



.9310 



1.0062 



.9126 



.9904 



1.0026 



25 



