SPECIFIC GRAVITY AND TREE WEIGHT OF SINGLE-TREE SAMPLES OF GRAND FIR^ 



Albert R. Stage 



SYNOPSIS 



Analysis of data from 108 grand fir trees sampled in northern 

 Idaho provided the following prediction equations for specific gravity 

 of 20-year periodic increment on the tree bole (S^^), average specific 

 gravity of the tree bole (Sgj^j-), and the dry weight of the tree bole (W): 



. 54 1 3 - . 0883 8( 1 /SC2q)+0 . 9907( 1 /H) 



0. 5579-0. 056l4(I/SC2o)-0.03299(l/SCent) 

 . 4422+0 . 001305(D^- H • SC^q) -0 . 1 990(C) 

 total tree height in feet 

 d.b.h. 



crown class 



specific gravity of the outer 20 rings of increment 

 core taken at breast-height. 



specific gravity of increment core to pith taken at 

 breast -height. 



Trends of specific gravity of the increment at different heights 

 in the tree were shown to be a function of distance from the apex, 

 crown length, and crown class. 



where: 



Sent 



W(cwt) 

 H 



D 



C 



SC 2Q 



sc 



ent 



Fieldwork for this study was conducted with the cooperation of Potlatch Forests, Inc. , 

 Inland Empire Paper Company, and the Forest Products Laboratory of the U.S. Forest Service. 



