28 
BULLETIN 1060, U. S. DEPARTMENT OF AGRICULTURE. 
of conditions which obtain in the virgin forest, it is possible to give 
an idea of what may be expected under average conditions. The 
number of trees and the yield per acre in Table 9 are based on the 
averaged and curved values of twelve sample plots from one-half to 
5 acres in size. On six of these plots Sitka spruce made up 88 to 
100 per cent of the stand by volume ; on five of them it made up 50 to 
82 per cent, and on one plot it comprised 25 per cent. The plots 
were in essentially even-aged stands, except that the older stands 
contained an underwood of younger hemlock and cedar trees. 
Table 9. — Average yield per acre of stands of Sitka spruce and associated species 
on good quality sites in Oregon and Washington. 
(Curxed ) 
Age. 
Trees Yield 
per per 
acre. ! acre. 
; 
Mean 
annual 
growth. 
Age. 
1 
Trees j Yield 
per per 
acre. acre. 
Mean 
annual 
growth. 
Years 
40 
IBoardfeet 
400 29. 500 
Board feet 
734 
904 
975 
995 
958 
900 
838 
Years 
180 
82 
70 
60 
50 
42 
36 
30 
Board feet 
140, 000 
144, 750 
148,250 
151, 000 
153, 000 
154,250 
155, 500 
Board fett 
778 
60 
280 
220 
175 
130 
112 
94 
54, 250 
78, 000 
99,500 
115,000 
126,000 
134, 000 
200 
724 
80 
220 
674 
100 ! 
: 240... 
629 
120 
260 
588 
140 
1 280 
551 
160 
300 
518 
1 
As represented by the figures in this table, the yield of spruce 
stands compares well with that of Douglas fir on the best sites. Up 
to 90 years it makes a better yield, at 100 years it equals, and there- 
after it falls a little behind Douglas fir. 16 The yields of the table 
are those of the virgin forest; if proper methods of forest manage- 
ment were employed, and if the trees were thinned at regular inter- 
vals, these yields would be considerably increased. The rapid incre- 
ment of Sitka spruce is especially evident when the periodic annual 
growth is considered, which between the ages of 40 and 60 years is 
1,237 board feet. 
MANAGEMENT. 
Since Sitka spruce does not ordinarily grow in pure stands, but 
rather in intimate mixture with several other commercial trees, the 
principle of management which must be applied to spruce should be 
equally applicable to its associates — fir, hemlock, and cedar. The 
entire forest of which Sitka spruce forms a part must be treated uni- 
formly. Hence the discussion of the management of spruce is inter- 
woven with considerations of the other trees in the stand. 
It has been shown that Sitka spruce is a very excellent timber tree, 
that its wood is superior to that of all others in the region for certain 
10 Manuscript report by E. J. Hanzlik, Forest Service, Mar. 14, 1912. 
