kg = 0.14082397X10"^^ Z3 = H (A^ - 50^) 



ki, = -13,140.717 1^ = H^(A'^ - 50"^) 



ks = 0.13492191X10"'' Z5 = H^(A"2-50"^) . 



For this equation the standard error of estimate is 0.90 foot. 



These equations are valid for ages from 20 to 200 years and for site indices from 



10 to 110. The site index of trees older than 200 years should be estimated as if age 

 were 200. 



GRAND FIR^ 



Site Index 



Information on productivity of grand fir has been developed using a direct index 

 of relative productivity (Q) rather than site index. Procedures for calculating Q from 

 stand age and height have been published (10). Figure 10 shows a FORTRAN program RPGF . 



SUQRCUTINE KPGFI C,H,T,CR,I£R ) 



rCUBLE PRECISION A , B , C , , X , 8 T , C E T , T(JL , V AL , PR AC , A LGCK 

 CI^'ENSICN C(5) 



CAFA C /-lO .2^1Sb^, 2.0, 0.018167, -2.7 , 2.0 / 



CIV = 0.3 



I L*^ = 



IGT = 1 



CGR = C. 



I = C 



HT =-C(3)*(r + Cl-^) ) 



IF ( T - 90. ) 91,91,92 



n TUL = COCO 



GC TC 9 5 

 92 TOL = ALCG( 0.e*h/T ) 



95 ALGCR = ALCG(ll-^.5) - ( AL OG ( C R ) - 3 . 74 7 ^ 7 A- 8 . 2 1 8 30 5 / T ) « 1 8 . 7 86 /T 



TS = TCL 

 99 I F ( TCL .G r. 20. ) GC TU 101 



CET = HT*DEXH( TCL ) 



IF ( CET ) 991,100,100 



991 BRAG = I.OCO - DEXP(DET) 

 IF (HRAC) 100,100,992 



992 TfiL = C(l) + C(2)*{ALGCR - C ( 5 ) *CLOG ( BRAG) ) 

 1 = 1 + 1 



996 CV. TC ( 2 I, 22, 23) , IGT 

 21 X = TCL 



A = X - rs 



(con. next page) 



-'The section on grand fir was contributed by Albert R. Stage, Principal 

 Mensurationist , Intermountain Forest and Range Experiment Station. 



17 



