Fire 
Range fires burn over about 2 million acres of rangeland each 
year. Assuming »n average grazing capacity of 6 acras per animal 
uwnit-month, the annual ioss of forage destroyed by fire represents 
about 330,000 animal unitemonths of prezing. Assuming an averave 
value of $2 ver animal unit-month, the forage thus lost by fire 
has a direct value of about $666,000 annuelly. (Table 9). These 
fire losses alse disrupt ranch operations and thus cause additional 
losses. In many cases additional losses result from the more 
permanent. damage to perennial range svecies and deterioretion of 
site. 
Grasshoppers 
About 20 species of grasshenpers are esnecially destructive to 
rangeland in the West, where they consume large quantities of 
forage that would otherwise support valuable livestock. The over- 
all loss on 845 million acres of Federal, State, and private range= 
land in 17 western States has been estimated at approximately 
HES 00,000 annually. For losses to crops by grasshoppers, see 
Chapter V. 
Mdesirabie Plants 
Grazing values on approximately 21,0 million acres of rangeland 
have been severely reduced or elimineted by the invasion of un- 
desirable trees and shrubs such as mesquite, juniper, sagebrush, 
and post. oak. Assuming an average reduction of 50 percent in 
prazing capacity on these areas ard acres per animal unit-month, 
the annual loss in grazing capacity amounts to about 30 million 
animal unit-months. This represents a loss of about 12 percent 
of the total potential rangeland, and at an average rate of #2 
per animal unit-morth a loss in grazing values of shout #60 million. 
In many areas poisonous or noxious plants cause additional losses 
of livestock. The annual loss of animals in Colorado aione attri- 
butable to poisonous plants averages sbout $1 million. Losses from 
poisonous plants in the range country as a whole average about bh 
percent of the animals grazed. The poisonous plant halogeton now 
occupies about 2 million acres in the Western States and is rapidly 
spreading. Much rangeland is no longer usable for grazing because 
of the hazards of halogeton poisoning of sheep and cattle, and 
ranch values in many areas have materially depreciated. Othar 
unpalatable plants, such as 5t.-Johns-wort and tne medusa wilderye, 
likewise are randering large range areas useless and bring about 
serious losses in livestock and ranch values, Tosses to livestock 
from plant poisoning are discussed in Chapter X and are included in 
Tables 20 to 2h. 
