2 BULLETIN" 791, TL. S. DEPARTMENT OF AGRICULTURE. 
observations of the abundance and luxuriance of the forage supply 
and upon the condition of the stock grazed. The depletion of the 
lands is seldom recognized by these general observations until their 
carrying capacity has been materially reduced, or until the animals 
grazed are in poor condition of flesh. So long as the cover is more 
or less intact, there is little indication that the range is being slowly 
but certainly depleted ; the depletion is not recognized until the more 
palatable and important forage species are in low vigor, and their 
growth and reproduction seriously impaired, or perhaps not until a, 
large proportion of the plants actually have been killed. Until there 
is insufficient feed to support the animals, they will retain their con- 
dition of flesh fairly well ; but long before there is insufficient feed to 
satisfy their appetites a large portion of the vegetation is killed. 
To reestablish the stand after impoverishment has reached such an 
advanced stage requires many seasons of most skillful management. 
Enterprising stockmen and those concerned with the administra- 
tion of grazing know that the live-stock industry has now reached a 
point where the intensity of the use of the forage crop must be gov- 
erned by a finer discrimination than mere observation of the density 
of the plant cover and the condition of the stock. The margin be- 
tween what clearly constitutes overgrazing and what is clearly under- 
grazing must be reduced to a minimum if the lands are to be utilized 
within from 10 to 20 per cent of their maximum carrying capacity 
and the herbage cropped on the basis of a sustained yield. 
The most rational and reliable way to detect overgrazing is to 
recognize the replacement of one type of plant cover by another. 
Certain more or less temporary species almost invariably succeed the 
more stable weakened or killed plants on lands that are being over- 
grazed, hence the incoming species are the most reliable indicators 
of small departures from the normal carrying capacity of the range. 1 
It is the object of this bulletin to point out what plants are reliable 
indicators of overgrazing in the various types and how they may be 
used as guides in revegetation and the maintenance of the forage crop. 
SUCCESSION OR THE DEVELOPMENT OF VEGETATION. 
In studying the laws underlying the occupation of lands by vege- 
tation from its earliest stages to the development of the highest type 
of plant life which the habitat is capable of supporting, a somewhat 
1 Shantz, H. L. (Department of Agriculture Bulletin 201, 1911), Kearney, T. H., 
Briggs, L. F., Shantz, H. L., McLane, J. W., and Picmeisel, R. L. (Journal of Agricul- 
tural Research, 1:365-417, 1914), and others, have shown that th,e character of the 
native vegetation affords a reliable index of the conditions favorable or unfavorable to the 
production of farm crops, and have incidentally established correlations between the native 
vegetation and the available moisture and the physical and chemical properties of the 
;soil. Relationships between the native vegetation and the carrying capacity of range 
Jands have been developed through the investigations here reported, application of which 
appears to be of far-reaching importance in the judicious management of the lands. 
