Fraction Cull in Total Stem Cubic Foot Volume Given tine Tree is Unsound — Unforked and 

 Forked Trees 



To predict the fraction of an unsound tree's total stem cubic foot volume that is 

 in cull, the following functional relationship is used: 



Y 



FC^ = ^^(1-0 - e *) 



where 



Predicted fraction cull in total stem cubic foot volume given the tree is 

 unsound 



a constant - , _ . 



A function of the tree's measured attributes. 



The sp-NF specific values and functions of h, and Y ^ respectively, the number of trees 



used, and the resulting RMSQR values are found in table 12. An examination of the RMSQR 

 values indicate that many of the equations might not reduce the squared deviations more 

 than a mean value of FC^. This is due both to the general difficulty of modeling cull 

 rates and to the relatively small number of sample trees with cull. It is felt, 

 however, that the equations do represent cull trends in at least the sample trees and 

 that they also seem to behave reasonably well. It is recommended, therefore, that the 

 equations be used but, for those who choose not to do so, mean values of FC^ have also ■ 



been included in table 12. Methodological details can be found in appendix XI. 



Table 12. — Fract-ion cull in total eteiv cubic foot volume^ jiven the tree 

 is unaouTui, dita haee and regression results 



Independent variables 

 D = D.b.h. in Inches H = Total tree height in feet 



Species, National Forest, and regression results 



Mean 

 1 FC^ 



Number 

 of 

 trees 



Relative 

 mean squared 

 residual 

 (RMSPR) 



White pine on Santa Fe , Carson, and Lincoln 









= 0.573840391 









= (-7.66323806E-0HD- 



0.14358 



34 



0.8358 



Engelmann spruce on Santa Fe, Carson, and Lincoln 









= 0.938462956 









V = -3.01894250E-01 * 4 . 30560743E-03 (H) 



.13981 



44 



.8359 



-6.43668344E-04 (D^) 









CorKbarJt fir on Santa Fe and Carson 









= 0.961637598 









- 1.3655729OE-01 - 5.67626653E-02 (^-j 

 t D 



.09807 



21 



.8472 



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









' 0.915201231 









Y^ - (-1.63671565E-01) * ( 3 . 255035O6E-05) DH 



.09303 



154 



.9716 



Blac)cjac)c pine on Lincoln, Coconino, and Tonto 









- 0.970852066 









Y^ - (-9.71749091E-03) - 16. 33508782E-07)D^H 



.01878 



80 



.9364 



Blackjack pine on Santa Fe and Carson 









- 0.959154988 









Yj - (-2.67485517E-02) - (7 . 47306053E-02) HA)^ 



.04676 



90 



.9727 



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









- 0.236595402 









Y^ - (-2.74212212E-01) - (6 . 75308810E-O6) D^H 



.08489 



66 



.9818 



Aspen on Santa Fe and Carson 









- 0.885502084 









Yj - (-2.1547562E-01) - (9. 32233189E-03)D^ * (1 . 31076200E-O3)DH 



.28482 



139 



.7441 



White fir on Santa Fe , Carson, and Lincoln 









- 0.44069748B 









Y^ - (-1.21221834E-03)D^ 



.15895 



51 



.7790 



18 



