16 
BULLETIN' 141, TJ. S. DEPARTMENT OP AGRICULTURE. 
grazing, while only 2.6 per cent were killed and 5.7 per cent injured 
by grazing. 
Table 7. — Summary of aspen sprouts hilled and injured by cattle grazing on clear-cut 
plots. 
Grazing intensity and year of 
examination. 
Total 
number 
sprouts. 
Uninjured 
sprouts. 
Killed by 
grazing. 
Injured by 
grazing. 
Total num- 
ber dead 
sprouts not 
killed by 
grazing. 
Injury not 
due to 
grazing. 
Lightly grazed: 
1915 
150 
166 
379 
311 
40 
36 
Num- 
ber. 
109 
140 
282 
274 
16 
21 
Per 
cent. 
72.7 
84.4 
74.4 
88.1 
40.0 
58.3 
Num- 
ber. 
7 
Per 
cent. 
4.6 
Num- 
ber. 
Per 
cent. 
Num- 
ber. 
20 
4 
46 
13 
1 
2 
Per 
cent. 
13.3 
2.4 
12.2 
4.2 
2.5 
5.6 
Num- 
ber. 
14 
16 
24 
10 
Per 
cent. 
9.4 
1916.. 
6 
15 
14 
15 
12 
3.6 
3.9 
4.5 
37.5 
33.3 
9.6 
Moderately grazed: 
1915 ... 
12 
3.2 
6.3 
1916 
3.2 
Heavily grazed: 
1915 
8 
1 
20.0 
2.8 
1916 
Total 
1,082 
842 
"77.Y 
28 
**2."6' 
62 
"5.T 
86 
'"§"6" 
64 
Mean of all grazing intensities. . . 
5.9 
COMPARATIVE INJURY TO ASPEN SPROUTS BY SHEEP AND CATTLE. 
The damage to reproduction on sheep range, on the plots estab- 
lished both in standing timber and on clear-cut lands, was consider- 
ably different in character and extent from that on cattle range. 
This difference in the degree of damage was evident in all localities 
where the study was conducted, and especially where plots had been 
grazed to practically the same degree of intensity. 
On plots in standing timber the comparative damage by sheep and 
by cattle may be summarized as follows (data given in Tables 1, 2, 
and 6) : 
(1) The average per cent of reproduction injured by sheep grazing 
from 1912 to 1916, inclusive, was 27.3, and from 1915 to 1916, in- 
clusive, 19.9. During the latter period the average per cent of injury 
on cattle range, where the forage had been cropped to practically 
the same extent, was but 3.97. 
(2.) The average per cent of reproduction killed on the plots scat- 
tered over the sheep allotments from 1912 to 1916, inclusive, was 17.1, 
and during 1915 and 1916, 24.8. During 1915 and 1916 less than 0.5 
per cent of the reproduction on the plots grazed by cattle was killed 
by browsing. 
On the clear-cut plot's the damage to reproduction by sheep as 
compared with' that by cattle is proportionately much more serious 
than on plots in standing timber. The seriousness of normal sheep 
grazing on clear-cut aspen lands may be summarized in the statement 
that in the third year following the removal of the standing timber 
it may be expected that no sprouts whatsoever will be found on the 
lands. If any sprouts remain, they are usually so mutilated as either 
to die after a season or two or so deformed as to produce timber of 
