8 BULLETIN Ml, U. S. DEPARTMENT OF AGRICULTURE. 
ness so long as the branches are within reach of the sheep. Further- 
more,, the sprouts listed in Table 5 which have the least height growth, 
viz, those '"less than one season old" and those ' 'below 6 inches, one 
season old," are undoubtedly protected from grazing by the rather 
luxuriant cover of herbaceous vegetation which characteristically 
occurs in the aspen type after about August 1 and hides much of the 
reproduction from view. The sprouts in these classes show a con- 
siderably smaller percentage of grazing than those of greater height. 
However, the loss chargeable to grazing is considerable, and owing 
to the succulence of the entire aerial parts during the first season 
of growth there were numerous individual sample plots representing 
large areas where on account both of the climatic conditions and of 
browsing the greatest injury to sprouts was inflicted during the initial 
season of growth. 
In view of the mortality of 1-year-old sprouts due to browsing 
and causes other than browsing, it may be concluded that even light 
cropping of the lands is sure to have a deter minin g effect on the ulti- 
mate timber stand. The extent to which the land should be grazed 
when the sprouts are just beginning to appear, therefore, should be 
determined bv the timber stand ultimatelv desired. 
Table 5. — Injuries to sprouts lh feet or less in height according to varying intensities 
of grazing; data grouped by seasons and height classes and according to intensity of 
grazing. Plots in standing timber. 
Lightly grazed. 
Moderately grazed. 
Heavily grazed. 
Total 
num- 
ber 
grazed 
all 
inten- 
sities. 
Per 
cent 
grazed 
all 
inten- 
sities. 
Season and height 
class. 
Total 
num- 
ber. 
Num- 
ber 
grazed. 
Per 
cent 
grazed. 
Total 
num- 
ber. 
Num- 
ber 
grazed. 
Per 
cent 
grazed. 
Total 
num- 
ber. 
Num- 
ber 
grazed. 
Per 
cent 
grazed. 
1912 
93 
899 
783 
386 
216 
122 
5 
262 
737 
261 
248 
4.09 
30.08 
40.36 
18.56 
26.80 
1.54 
458 
2,150 
2,192 
848 
16 
224 
1,462 
1,363 
88 
10.38 
4S.90 
68.00 
62.18 
10.30 
21 
773 
2,498 
1,678 
366 
5.61 
1913 
287 
299 
54 
30 
31.92 
871 
34.69 
1914 
38.18 
13.98 
13.90 
1,826 
1,405 
924 
52.48 
1015 
42.00 
1916 
18.40 
Total 
2,382 
670 
*28."i9" 
19.4 
20.9 
23.4 
5,148 
1,513 
29.38 
21.3 
18.3 
33.0 
36.2 
5,802 
3, 153 
*54.*34" 
52.8 
51.5 
37.8 
73.7 . 
5,336 
1,455 
1,088 
797 
1,867 
Average 
40.02 
Height class: 
Sprouts less than 1 
season old 
1-vear-old sprouts 
lto l.cieet 
Sprouts below 6 in- 
inches (1 season 
old) 
551 
315 
625 
891 
107 
66 
146 
3-55 
1,711 
1,103 
991 
365 
202 
328 
486 
1,861 
1,592 
854 
1,395 
983 
820 
323 
1,026 
35.2 
26.0 
32.1 
6 inches to 1.5 feet 
(1 season old) 
39.9 
1,343 
51.4 
SUMMARY. 
The effect of sheep browsing in standing aspen timber may be 
summarized as follows : 
(1) Of the total number of sprouts examined during 1912 and 1913, 
inclusive, the percentage of seriously injured and killed sprouts was 
