Table 4. - -Five-year diameter growth breast high and average crown length 



by vigor and crown class 



\^ X \J VV 11 X- J-Ci. ij tj 



Good vigor 



Fair vigor 



Poor 



vigor 



Ave rap's * 



Average 



crown : . 



increment 



length : 



Average 

 crown 

 length 



[ Average 

 ] increment 



Average 

 crown 

 length 



\ Average 

 increment 





Percent Inches 



Percent 



Inches 



Percent 



Inches 



Dominant and 













codominant 



68.5 0.827 



61.1 



0.666 



55.7 



0.468 



Intermediate and 













suppressed 





51.2 



.482 



34.0 



.345 



Gross volume increment in relation to time. - -Because volume of trees is dependent upon 

 diameter and height, it is expected that volume increment will respond to treatment the same 

 as diameter growth has. As shown in table 5, 5-year periodic annual volume increment in- 

 creased substantially in the second 5-year period (6 to 10 years after logging). The periodic 

 annual increment continued to increase in all but the last 5-year period, when it began to fall 

 off slightly. The study shows that in partial stands of this kind, residual spruce can be ex- 

 pected to accelerate its increment and continue to grow well for 25 to 30 years after logging. 



Table 5. - -Gross volume increment per acre of surviving residual 



trees and ingrowth 



Species 

 and 



Periodic annual increment 



Years after logging 



Total 

 30 -year 

 in- 



P.A.I. 



30-year 



tree class : 







-5 



: 6-10 



: 11-15 



: 16-20 



: 21-25 



: 26-30 



: crement : 















- Board feet - - 









Engelmann spruce: 





















Residual 



64. 



6 



113.0 



133.0 



158.2 



190.2 



189.0 



4,240 



141.3 



Ingrowth ^ 













2.8 



.2 



15 



.5 



Total 



64. 



6 



113.0 



133.0 



158.2 



193.0 



189.2 



4,255 



141.8 



Subalpine fir: 





















Residual 



7. 



6 



10.4 



15.2 



18.4 



16.2 



13.4 



406 



13.5 



Ingrowth 







5.6 



14.0 



2.0 



3.2 



39.8 



323 



10.8 



Total 



7. 



6 



16.0 



29.2 



20.4 



19.4 



53.2 



729 



24.3 



Trees 9.6 inches d.b.h. and larger at time of logging. 

 ^ Trees reaching 9.6 inches d.b.h. and larger size after logging. 



7 



