24 



BULLETIN 1060, U. S. DEPARTMENT OF AGRICULTURE. 



many other conifers ; but thereafter it increases in size with great 

 rapidity and maintains a fast growth until late in life. Its rate of 

 growth naturally varies with the quality and the character of stand. 

 Moisture conditions are an important factor and growth is more 

 rapid on wet bottomland situations than on the drier slopes. The 

 growth of Sitka spruce varies also in different parts of its range, and 

 is more rapid in Oregon, Washington, and British Columbia than 

 either farther south or north. Average figures on height, diameter, 

 and volume growth are given in the tables that follow, but it is real- 

 ized that these are not universally applicable. In the appendix will 

 be found tables of growth from several different localities. 



HEIGHT. 



In the seedling stage the height growth of Sitka spruce is fairly 

 rapid, but not so fast at this period as that of its associates, Douglas 

 fir, western hemlock, and western red cedar. Table 5 shows the 

 height growth of dominant, open-grown Sitka spruce seedlings, and 

 is compiled from measurements taken of young trees which grew in 

 seven different localities and sites in Oregon and Washington. Here 

 the reproduction was sometimes found in pure stands, but more often 

 in mixture with other species. 



Table 5. — Height of dominant, open-grown Sitka spruce seedlings, averaged for 

 all sites in Oregon and Washington. 



[Based on 2,102 sectional measurements of 322 trees.] 



(Curved.) 



Age. 



Height. 



Current 

 annual 

 growth. 



Age. 



Height. 



Current 

 annual 

 growth. 



1 



Years. 



Feet. 

 0.2 

 .5 

 1.0 

 1.6 

 2.2 

 2.8 

 3.5 

 4.4 

 5.4 



Feet. 



0.2 

 .3 

 . 5 

 .6 

 .6 

 .6 

 .7 

 .9 



1.0 



10 



Years. 



Feet. 



6.6 



8.0 



9.8 



12.0 



14.4 



17.2 



20.2 



23.4 



Feet. 

 1.2 



2 



11... 



1.4 



3 



12 



1.8 



4 



13 ' 



2.2 



5 



14 



2.6 



6 



15 



2.8 



7 



16 



3.0 



8 



17 



3.2 



9 











After the early years, growth increases rapidly and is maintained 

 at a good rate until late in life. In the sapling stage a growth of 3 

 feet and over a year is not unusual. At the age of 50 the average 

 dominant tree is still growing 1.7 feet per year, and at 100 years as 

 much as 1 foot. At these ages the height growth of spruce compares 

 very favorably with that of Douglas fir. This comparison is made 

 from the available growth tables for the species mentioned, under con- 

 ditions representative for each species, and not by comparison of the 

 several species growing side by side on the same site. 



