EFFECT OF GRAZING UPON ASPEN REPBODUCTTON. 17 
questionable value. Reproduction on clear-cut lands located on 
cattle range, on the other hand, while damaged more or less by 
browsing, appears to occur in sufficient density over the plots under 
observation to insure a maximum stand of first quality mature timber. 
Practically without exception there are no young aspen sprouts 
on range grazed annually by sheep during the period that the sprouts 
are being produced. The few sprouts found are almost invariably 
lacking in vigor and are often more or less seriously diseased. On the 
range used exclusively by cattle it is the exception not to find at least 
a partial stand of sprouts varying in age, most of which are vigorous 
and healthy. Cattle naturally prefer the leafage of herbs, especially 
grasses, to shrubs and other woody plants, and while they browse 
aspen reproduction, the damage they do seldom endangers the per- 
manent establishment of the stand unless the range is stocked with 
cattle beyond its natural carrying capacity. 
An analysis of the character of the injuries showed that the pro- 
portion of terminal and lateral shoots browsed was practically the 
same on cattle and on sheep allotments. It was quite evident, 
however, that the cattle browsed the foliage more and the woody 
tissue less than sheep; consequently the complete removal of ter- 
minal and lateral shoots was less commonly observed on the cattle 
ranges than on the sheep ranges. The difference would appear to 
account for the more rapid and complete recovery of injured sprouts 
on cattle allotments. 
Practically no damage is caused to aspen reproduction by rubbing 
and trampling by cattle. Rubbing is generally confined to young 
conifer saplings characteristically scattered through the aspen type, 
the needles and bark of which afford the friction desired, or to aspen 
specimens of about pole size. Young aspen sprouts are so limber that 
stock seldom break the branches or otherwise distort them by rubbing. 
Sheep, of course, not being addicted to the rubbing habit like cattle, 
cause virtually no damage in this way. Trampling by either class 
of stock causes very slight mortality or permanent injury. On sheep 
ranges the young sprouts are either killed or seriously damaged long 
before the formation of prominent trails which might otherwise 
result in trampling out the reproduction. On cattle allotments there 
is occasionally a small amount of damage to young sprouts by tram- 
pling, portions of the bark being removed along the main stem or 
the specimen being broken; but such injury is negligible on lands 
stocked according to their actual carrying capacity and on which the 
animals are properly distributed. Where cattle have a tendency to 
congregate, however, near watering and salting places, for instance, 
both browsing and trampling have a telling effect on the density and 
vigor of the reproduction.. 
