PLANT SUCCESSION AND RANGE MANAGEMENT. 21 
Owing to the small amount of precipitation that penetrates beyond 
the shallow matlike surface of the turfed wheat-grass type, bunch 
wheat grasses and other deep-rooted species are seldom associated 
with a fully established stand of the sodded wheat-grass cover. The 
bunch wheat-grass type, on the other hand, supports a considerable 
variety of weeds and other plants, both of deep and of shallow 
rooted characteristics. 
Regardless of the growth form of the wheat-grass cover, yellow 
brush {Chrysotkamnus lanceolatus) is the most characteristic fore- 
runner of other aggressive perennial plants which gain a foothold 
as the wheat grasses are killed out by overgrazing or other adverse 
factors. Small mountain porcupine grass is commonly associated 
with the yellow brush,. As the turfed wheat grass is reestablished, 
yellow brush and porcupine grass are entirely replaced. In the re- 
vegetation of the bunch wheat-grass cover, both yellow brush and 
porcupine grass are rather persistent, as the moisture conditions re- 
main comparatively favorable to the invading species until the 
original grass cover is fully reestablished. Eventually, however, 
most of the yellow brush and porcupine grass plants are crowded 
out. Thus the invasion and conspicuous establishment of yellow 
brush and porcupine grass on the wheat-grass type generally indicate 
clearly that one or more unfavorable factors are at play, which, if 
permitted to continue, may result in the destruction of the wheat- 
grass type. On the other hand, the waning of the indicator plants, 
due to competition with the wheat grass, affords reliable evidence of 
the reestablishment of the wheat-grass type. 
There is relatively little difference in the number of cattle and 
horses that the turfed and the bunched wheat-grass areas are capable 
of supporting in good condition. Sheep, on the other hand, make 
better returns on typical bunch wheat-grass lands than on the turfed 
areas because of the greater variety of forage which the bunch-grass 
type usually supports. In spite of this fact, however, no attempt 
should be made to overgraze either grass cover with the idea of im- 
proving the lands for the grazing of sheep. To do so will seriously 
decrease the forage production of the lands for the grazing of cattle 
and horses. After a few years of full utilization of the wheat-grass 
consociation by cattle and horses a large variety of plants usually ap- 
pears. This natural replacement of the palatable grasses by plants 
successionally lower in the scale of development will improve the 
lands for the grazing of sheep and thus bring about a condition which 
will justify cropping by all classes of stock in proper proportions. 
Where common use of a wheat-grass range is resorted to, after the 
cover has partly reverted to the weed stage, the cattle grazed should 
be reduced in number to the point where the remaining vegetation 
palatable to this class of stock will be safe from further destruction. 
