EFFECT OF GRAZING UPON" ASPEN REPRODUCTION. 
23 
Table 10. — Sprouting capacity and height growth of aspen reproduction on clear-cut 
plots. 
Date of examination. 
Fall cutting, 1912. 
Number of 
living 
sprouts 
per acre. 
Average 
height. 
Spring cutting, 1913. 
Number of 
living 
sprouts 
per acre. 
Average 
height. 
Summer cutting, 1913. 
Number of 
living 
sprouts 
per acre. 
Average 
height. 
Inches. 
Summer, 1913. 
Fall, 1913 
Spring, 1914... 
Fall, 1914 
Spring, 1915... 
Fall, 1915 
Spring, 1916... 
Fall, i916 
41,700 
32.670 
34, 700 
32,810 
22,210 
24, 100 
21,920 
8.6 
23.4 
25.5 
39.2 
39.8 
43.1 
11,600 
33, 800 
27,590 
85, 520 
62,580 
39,920 
37, 609 
29, 910 
Inches. 
7.3 
12.5 
15.5 
31.4 
32.5 
41.2 
50,960 
44,140 
43,850 
42,730 
31,070 
Inches. 
16.9 
20.3 
34.0 
34.1 
Table 10 shows that the production of sprouts is heavy on all 
areas, regardless of season of cutting, and that in general the maximum 
number of sprouts is in evidence within a season following the removal 
of the timber. Considering the number of mature, well-developed 
trees that may occupy the ground, more than enough sprouts are 
produced on the respective plots regardless of season of timber 
removal. The most vigorous sprouting occurred on the plot the 
timber of which was removed in the spring, and the least vigorous on 
the autumn-cut plot. On the spring-cut plot, however, the death 
rate of sprouts was greatest. The rate of growth was relatively 
uniform and approximately the same on each plot, and the annual 
increment averaged about 15 inches, the height growth being practi- 
cally the same from season to season. 
From the above facts it may be concluded that (a) regardless of 
season of cutting a sufficient number of aspen sprouts is produced 
on clear-cut lands to restock the lands fully, provided grazing is 
properly controlled; and that (b) in general the reproduction will 
have attained sufficient height by the end of the third, year of growth 
to be exempt from destructive browsing by sheep, and by the end of 
the fourth, or more certainly the fifth year, to be out of danger from 
cattle. 
SILVICULTURAL MANAGEMENT OF ASPEN. 
METHODS OF CUTTING. 
Experimental evidence gathered from variously treated plots 
points to the fact that if the lands are to be devoted permanently to 
the production of aspen, clear-cutting or repeated heavy thinnings 
are the best means by which to secure vigorous sprouting and an 
evenly distributed stand. 
As is shown by the sparse stand of sprouts on the plots established 
in the standing timber, aspen is practically unable to reproduce 
