26 
BULLETIN 1291, IT. S. DEPARTMENT OF AGRICULTURE 
Table 13. — Height growth of sproui 
Age 
Height 
Age 
Height 
1 year . 
Inches 
15.1 
27.5 
41.4 
50.8 
5vears ... 
Inches 
1 55.9 
2years 
1 60. 
7years .. . . 
1 62.7 
i Estimated on basis of one plot only. Slow growth the seventh year is due chiefly to serious frost 
damage which even killed back sixth years' growth in some cases. 
After the first rapid growth is over, however, the height growth of 
aspen slackens materially, while the conifers of equal age are in full 
vigor. The results of the differences in rate of height growth be- 
tween aspen and the associated conifers is shown in Table 14. 
It will be noted that alpine fir is able to equal the height of aspen 
on site quality 2 in 150 years; and that in time all the conifers ap- 
proximate or exceed the maximum height of aspen, although, owing 
to its rapid juvenile growth, they are not able to overtake the aspen 
before it dies. On site quality 1 even alpine fir is probably unable 
to catch up with aspen before the aspen dies, although its final 
height is greater. On sites poorer than quality 2 the conifers un- 
doubtedly fare relatively better, although data are lacking for a 
close comparison of aspen and conifer development. 
Table 14. — Height growth of aspen eompared with that of eonifers 
Height 
Age 
Aspen, 
Site 2 i 
Douglas 
fir' 
White 
fir' 
Alpine 
fir' 
Engel- 
mann 
spruce' 
Feet 
10 
16 
24 
31 
37 
43 
48 
53 
57 
60 
62 
64 
65 
67 
68 
Feet 
0.6 
2 
5 
10 
16 
24 
30 
35 
39 
43 
46 
49 
52 
55 
57 
59 
61 
63 
65 
67 
Feet 
0.6 
2 
4 
7 
12 
22 
28 
33 
37 
41 
44 
47 
50 
53 
55 
57 
59 
61 
63 
65 
Feet 
0.6 
2 
4 
9 
17 
28 
37 
43 
48 
53 
57 
60 
63 
66 
68 
70 
71 
72 
73 
74 
Feet 
20 years... ... 
4 
30years 
5 
40vears 
6 
7 
60years . . . ... .. 
9 
12 
SOyears . ... 
16 
90years 
22 
lOOyears. 
29 
HOvears ... .____ . 
36 
120vears ..... . 
43 
130years _ . . 
50 
55 
60 
160 years - 
63 
66 
180years . 
69 
190 vears 
72 
200 years 
75 
1 Results from plots of site quality 2. measured for yield. 
2 Results from conversion of diameter growth (Table 14) into terms of height growth, 
by diameter-height tables. 
3 From Forest Service Circular 170, " Engelmann spruce in the Rocky Mountains," 
p. 10. 
DIAMETER GROWTH 
The advantage possessed by aspen in the matter of height growth 
is much less pronounced when it comes to diameter growth, since 
