SITKA spkuce: uses, ■ growth, management. 



25 



The figures given in Table 6 indicate the average total height and 

 average annual height growth in each decade of older spruce of vari- 

 ous ages, averaged from the measurement of 554 dominant trees. The 

 figures are dependable for trees up to 300 years; beyond that age 

 reliable height-growth figures are difficult to obtain, because very old 

 spruce trees are commonly stag-headed. 



Table 6. — Average total height at various ages, and average annual height 

 growth in each decade of Sitka spruce on all sites in Oregon and Washington. 



[Based on 1,260 sectional measurements cjf 554 dominant trees.] (Curved.) 



Age. 



Average 



total 



height. 



Average 

 annual 

 height 

 growth 

 in each 

 decade. 



Age. 



Average 



total 

 height. 



Average 

 annual 

 height 

 growth 

 in each 

 decade. 



Years. 

 20 



Feet. 

 31 

 51 

 70 

 87 

 104 

 119 

 132 

 144 

 154 

 164 

 173 

 181 

 188 

 194 

 200 

 205 

 210 

 214 

 218 

 221 



Feet. 

 2.4 

 2.0 



1.9 



1.7 



1.7 



1.5 



1.3 



1.2 



1.0 



1.0 



.9 



.8 



.7 



.6 



.6 



.5 



.5 



.4 



.4 



.3 



Years. 

 220 



Feet. 

 224 

 226 

 228 

 230 

 232 

 233 

 234 

 235 

 236 

 236 

 236 

 237 

 237 

 237 

 237 

 237 

 238 

 238 

 238 



Feet. 

 0.3 



30 



230 



.2 



40 



240 



2 



50 



250 



.2 



60 



260 



.2 



70 



270 



.1 



80 



280 



.1 



90 



290 



.1 



100 



300 



.1 



110... 



310... 



.1— 



120 



320 



.1— 



130 



330 



.1— 



140 



340 



.1— 



1,50 



350 



.1— 



160 



360 



.1- 



170 



370 



.1— 



180 



380 



.1- 



190 



390 



.1— 



200 



400 



.1- 



210 











DIAMETER. 



Diameter growth in this species is remarkably rapid and well sus- 

 tained, as the figures in Table 7 indicate. In this table the figures 

 represent the average of measurements taken of 557 dominant trees 

 from seven localities in Oregon and Washington. Although its an- 

 nual rate of diameter growth culminates at about the age of 40 years, 

 it maintains a growth of over 3 inches per decade up to about 60 

 years, and thereafter for a few decades over 2 inches per decade. At 

 the advanced age of 400 years, the data in Table 7 indicate, the 

 diameter is still increasing at the rate of over 1 inch per decade. 

 Exceptionally rapid diameter growth is attained on wet sites, where 

 sometimes it may amount to three-quarters and even 1 inch annually 

 during early years of vigorous growth. Plate XX shows the 

 diameter growth of Sitka spruce. 



