EFFECT OF GRAZING UPON ASPEN REPRODUCTION. 
15 
70 
60 
SO 
30 
zo 
10 
EFFECT OF CATTLE BROWSING. 
Injury to reproduction on clear-cut aspen plots chargeable to 
browsing, trampling, and rubbing by cattle was observed during the 
seasons of 1915 and 1916 in the same detail as in the case of the 
plots located on the sheep allotments. Early in the spring of 1915 
two representative areas locate^ at an elevation of approximately 
8,800 feet were cleared of timber, and sample plots and quadrats were 
established, by means of which the rate of sprouting and the exact 
character of damage caused exclusively by cattle were noted. The 
clear-cut areas were 
comparable in every 
way, except that one 
was subject to normal 
grazing while the 
other was fenced 
against stock. 
In recording the 
damage to the repro- 
duction, account was 
taken of the injury 
and mortality due 
both to the presence 
of cattle and to 
causes other than 
grazing. The data 
were grouped accord- 
ing to grazing inten- 
sity. The results are 
summarized in Table 
7, and for purposes of 
ready comparison the 
data recorded in 1915, which are practically the same as for 1916, 
are shown graphically in figure 5. 
In 1915 the number of uninjured sprouts was highest on the lightly 
and moderately grazed plot» (72.7 and 74.4 per cent, respectively) 
and notably lower on the heavily grazed areas (40 per cent) . In 1916 
the relation was similar. There was practically no difference in the 
per cent of injured and killed sprouts on the lightly grazed and on 
the moderately grazed plots, while on those heavily grazed there 
was an appreciable increase in the percentage of both injured and 
killed sprouts. 
A considerable proportion of the sprouts on these plots, as in the 
case of sprouts on plots previously reported on sheep range, were 
injured or killed by causes other than grazing. Eight per cent of 
the sprouts died and 5.9 per cent were injured by causes other than 
/ 
/ 
/ 
/ 
/ 
/ 
/ 
/,y 
Lightly Grazed Moderately Grazed Heavily Grazed 
Fig. 5. 
«. Sprouts Uninjured By Grazing 
-Sprouts Injured By Grazing 
_ Sprouts Kilted By Grazina 
-Relation of cattle grazing to number of uninjured and 
killed sprouts, season 1915. 
