Merchantable Gross Cubic Foot Volume — Un forked Trees 



By definition, merchantable gross cubic foot volume in an unforked tree is equal 

 to total stem gross cubic foot volume minus the cubic foot volume in both the top and 

 the stump (Husch 1963) . This relationship can be written as 



V = - V 

 m t u 



where 



= Predicted merchantable gross cubic foot volume to a specified top in an 

 unforked tree 



V, = Predicted total stem gross cubic foot volume in an unforked tree 



V = Predicted unmerchantable gross cubic foot volume in an unforked tree (that is, 

 " the gross cubic foot volume in the top and stump of an unforked tree) . 



Weighted least squares regression was used to develop the following model for unmer- 

 chantable gross cubic foot volume in an unforked tree: 



dIh 



V = 2?o + ^1 



D 



where 



V = 



u 



Predicted unmerchantable gross cubit foot volume in an unforked tree 

 D = D.b.h. in inches 

 H = Total tree height in feet 



= Any specified top diameter between 3 and 8 inches inside bark 

 An sp-NF specific power on d.b.h. 



m 

 n = 



The appropriate regression coefficients, their RMSQR, and the number of observa- 

 tions used can be found in table 4. The number of observations differs from the number 

 of trees used because each tree has an unmerchantable volume for each of th^ several top 

 diameters computed for the tree. Methodological details can be found in appendix III. 



Table 4. 



— 'M forked tree urunerchnntable 



gross 



ozibic 



foot volume 



data base and regression results 









Number 

 of 



observations 



Power : 



Regression coefficients : 



Relative 



Species 



National 

 Forest 



: on : 

 : d.b.h. : 



bo 





^ :mean squared 

 : residual 

















(RMSQR) 



White pine 



Santa Fe, Carson, 



















Lincoln 



250 



1. 



5 



0.213005397 



0.00491211378 



0.00606061971 



0.0229 



Engelmann spruce- 



Santa Fe, Carson, 

















corlcbark fir 



Lincoln 



810 



1. 



5 



-.266475206 



.00612895037 



.00743111599 



.0503 



Yellow pine 



All 



1,206 



1. 







.0185465259 



.000788175798 



.00505513624 



. 1004 



Blackjack pine 



Lincoln, Coconino 



















Tonto 



4,086 



1. 



5 



-.125349396 



.00360421889 



.00540634204 



.0591 



Blackjack pine 



Santa Fe, Carson 



1,231 



1. 



5 



-.133967845 



.00650174839 



.00490223789 



.0657 



Douglas-fir 



Lincoln, Tonto 



648 



1. 







-.083148657 



.00121904459 



.00541744598 



.0547 



Douglas-fir 



Santa Fe, Carson 



424 



1. 



5 



-.187630869 



.00671872085 



.00536451038 



.0580 



Aspen 



Santa Fe , Carson 



528 



1. 



5 



-.236432433 



.00580208490 



.00608042504 



.0435 



White fir 



Lincoln 



244 



1. 







-.182699690 



.00124824607 



.00624477874 



.3681 



White fir 



Santa Fe, Carson 



298 



1. 



5 



-.187563245 



.00632648558 



.00604132385 



.0293 



7 



