Table 5. — Forked tree merchantable gross cubic foot volume data base 



and regression results 



Independent variables 



D = Top diameter, inside bark, in inches 



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 



Number 

 ! of 

 'observations 



: Relative 

 imeam squared 

 : residual 

 : (RMSQR) 



White pine on Lincoln, Santa Fe, and Carson 



101 



0.9581 



Cl 



= 0.61725167 + 0.042365845D 



n 



= 0.00598501 - 0.00073445D 



m 



R ^ = 1.04518089 - 7 . 88395198E~07D + 8 . 39079873E-08dS 



J m m 



Engelmann spruce-corkbark fir on Lincoln, Santa Fe, and 

 Carson 



Co 



= Co + Cl (D/H)-^ 

 = 0.88977465 + 0.01260886D 



91 



.9719 



m 



Cl = 2.02369991 + 0.00029092D 



m,f 



1.09275293 + 1 . 66824359E-06D^ - 2 . 2292a473E-07D^ 



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

 and Carson 

 R^ = Co + Cl (D/H)2 



Cn = 1.025717571 - 0.01509060D 



m 



= 0.13600973 + 0.09709709D 



m 



R ^ = 0.997113216 - 0.0233001250^ + CqT^ + CiP 



Co 



937 



937 



,9968 



.9761 



0.00564984 + 0.00079885D 



Cl = 0.002886816 + O.O233O013D 

 ' m 



, = 1.01577735 - 1 . 68401836E-06d5 

 n,* m 



Douglas-fir on Lincoln, Santa Fe, and Carson 



R^^^-^ = Co + CiH-1 + C2H-lD^ 



Co = 0.552116849 



Cl = 22.5535301 



C2 = 0.284962111 

 °^R^^^= 0.951125601 - 7 . 62321367E-04D^ + 2 . 09712628E-03D, 



Aspen on Santa Fe and Carson 

 R = Co + CiH2 



Co = 1.143728271 - 0.08851433D 



Cl = -0.000006413 + 0.000018827D 

 or ' m 



R = 1.07666448 - 1. 18133616E-03d2 • 5 

 rn, * m 



White fir on Santa Fe , Carson, and Lincoln 

 R , = Co + Cl (H/D^) 



.7] , * 



118 



.9064 



3.5 



184 



.9165 



74 



.7286 



Cl 



= 0.673711298 + 0.055948391D 



m 



= 1.709640750 - 0.348134538D 



9 



