10 
BULLETIN *lil 3 U. S. DEPARTMENT OF AGRICULTURE. 
controlled cattle grazing, such as has been carried out in the vicinity 
of these plots, and the perpetuation of the aspen stand are not neces- 
s arily an t a g onis t i c . 
The young, tender aspen shoots are browsed more or less by cattle, 
however, and the damage inflicted may increase in proportion to the 
density of the reproduction. Hence, where sprouts are produced in 
sufficient numbers to attract stock and accustom the animals to 
browse upon aspen, a greater per cent of damage may occur than 
where the stand of sprouts is sparse, as in standing timber. A 
maximum number of sprouts invariably follows clear-cutting, and 
accordingly the extent of injury by grazing to dense stands of repro- 
duction can best be determined on clear-cut plots. 
Table 6. — Total number of sprouts the laterals and terminals of which uere removed by 
cattle browsing on plots in standing timber; data grouped according to intensity of 
grazing and height classes. 
Season and height class. 
Lightly grazed. 
Moderately grazed. 
™yL dumber 
Per cent 
browsed. 
Total 
number 
sprouts. 
Number ; Per cent 
browsed, browsed. 
1915 
1916 
Height class: 
6 inches to 1.5 feet. 
1.5 feet to 2.5 feet.. 
2.5 feet to 3.5 feet.. 
3.5 feet to 4.5 feet.. 
150 
166 
3.2 
379 
311 
41 
83 
78 
52 
4.20 
4.87 
2.41 
2.56 
1.92 
Heavily grazed. 
All intensities of 
grazing. 
Season and height class. 
Total 
number 
sprouts. 
Number 
browsed. 
Per cent 
brows 
Total 
number 
sprouts. 
Per cent 
browsed. 
1915 
40 
36 
6 
15 
13 
17.50 
36.10 
10 
31 
2 
1.75 
1916 
6.20 
Height class: 
6 inches to 1 .5 feet 
2.60 
1.5 feet to 2.5 feet 
4 26.60 
6 3.20 
2.5 feet to 3.5 feet 
2 
1 
3.5 feet to J-.5feet 
i 
1.60 
INJURY TO ASPEN REPRODUCTION BY GRAZING ON CLEAR-CUT LANDS. 
EFFECT OF SHEEP BROWSING. 
Because of the high mortality due to natural causes the most 
authentic data showing the effect of grazing on the stand and the 
condition of the sprouts can probably be obtained by comparing the 
stands on similar fenced and unfenced clear-cut plots. Four plots 
were selected on typical aspen range and clear-cut in the fall of 1912; 
two of these were fenced against stock and the other two left unfenced. 
The data recorded on the two sets of plots are stirnrnarized in 
figures 2 and 3. Figure 2 shows for each season during which the 
observations were made (1) the rate of sprout production on normal 
