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. 



(Curved ) 



Age. 



Trees 

 per 

 acre. 



Yield 

 per 

 acre. 



Mean 

 annual 

 growth. 



Age. 



Trees 

 per 

 acre. 



Yield 

 per 

 acre. 



Mean 

 annual 

 growth. 



Years 

 40 



400 

 280 

 220 

 175 

 130 

 112 

 94 



Boardfeet 

 29, 500 

 54,250 

 78,000 

 99, 500 

 115,000 

 126, 000 

 134, 000 



Boardfeet 

 734 

 904 

 975 

 995 

 958 

 900 

 838 



Years 

 ISO 



82 

 70 

 60 



50 

 42 

 36 

 30 



Boardfeet 

 140, 000 

 144,750 

 148,250 

 151, 000 

 153, 000 

 154,250 

 155, 500 



Boardfeet 

 778 



60 



200 



724 



80 



220 



674 



100 



240 



629 



120 



260 



588 



140 



280 



551 



160 



300 



518 









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 



ia Manuscript report by E. J. Hanzlik, Forest Service, Mar. 14, 1912. 



