Total Stem Gross Cubic Foot Voliane — Forked Trees 



The model for total stem gross cubic foot volume of forked trees is 



R, 



V „ = V X 



where 



Predicted total stem gross cubic foot volume of a forked tree 



Predicted total stem gross cubic foot volume of an unforked tree 



Predicted ratio of actual total stem gross cubic foot volume in a forked 

 tree divided by predicted total stem gross cubic foot volume in an unforked 

 tree of same dimensions. 



The sp-NF specific equations for R, ^, their R>1SQR, and the number of trees used are 



tjj 



found in table 3. An examination of RMSQR values indicates that, in some cases, models 



are only slightly better than the mean of ratios. Therefore, the mean values for R, ^ 



tj J 



are also included in table 3 for those who do not feel comfortable using the equations. 

 Methodological details can be found in appendix II. 



Table 3. — Forked tree total stem auhia foot volume data base and regression results 



Independent variables 



D = D.b.h. in inches 



H = Total tree height in feet 



P = Height to first fork divided by H 



T = 1 + (number of forks) 



Species, National Forest, and regression equations 



: Mean 



: ^t,f 



Number 

 of 

 trees 



: Relative 

 :mean squared 

 : residual 

 : (Rf^SQR) 



White pine on Santa Fe , Carson, and Lincoln 











R ^ = 8.72597123E-01 + 2 . 96964121E-03 (H) 

 or '■' 



R , = 0.83242764 + 2 . 81237312E-05 (H^) + 1 . 67572359E-01 (P) 

 t i J 



1 



.03680 



17 



0.8803 



1 



.03680 



17 



.8137 



Engelraann spruce-corkbark fir on Santa Fe, Carson, and Lincoln 











R , = 9.92085233E-01 + 1 . 87806305 (D/H) 2 



or 



R ^ = 0.49137954 + 3 . 73898958E-02 (D) - 5 . 87687943E-05 (h2) + 5 . 08620456E-01 (P) 



1 



.12229 



16 



.7702 



1 



.12229 



16 



.5139 



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











R - = 9.86799996E-01 + 4 . 82642048E-01 (D/H) 2 

 or '■^ 



R 0.90259661 + 1 . 24540324E-02 (T^ ) + 9 . 74033859E-02 (P) 

 '•J J 



1 



.02667 



158 



.9889 



1 



.02667 



158 



.9374 



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











R , = 9.40292266E-01 + 3 . 38586950 ( 1/H) 



1 



.00723 



21 



.9790 



Aspen on Santa Fe and Carson 











R^ ^ = 9.49182022E-01 + 2 . 82537481E-05 (H^) 

 "'^R ^, = 1.36944003 + 3 . 87833769E-05 (H^ ) - 5. 61174592E-02 (T) 



1 



.02097 



37 



.9559 











+3.69440030E-01 (p2) - 7 . 38880060E-01 (F ) 



1 



.02097 



37 



.8975 



White fir on Santa Fe, Carson, and Lincoln 











R , = 9.10060854E-01 + 2 . 67134214E-01 (H/D^) 





.97591 



13 



.8752 



6 



