TENURE AND USE OE ARID GRAZING LANDS. 11 



have been done which tend to lower the productivity of the area. 

 One effect is a reduction in the total amount of water that enters the 

 soil, with a lessening of the amount available to the growing plants. 

 The amount of feed that plants produce varies almost directly as the 

 available water, up to the optimum amount. Therefore loss of the 

 water means loss of feed on any arid land, because the water supply 

 on such land is always less than might be utilized. 



Another effect of the removal of the grass is an increase in the ero- 

 sion produced by the water that runs off [83] 9 . Nothing protects a 

 soil from erosion so well as a thick sod of grass. Any practice which 

 retards the rate of flow of the water reduces its erosive power many 

 fold. All erosion takes away the finer soil and leaves a surface upon 

 which the desirable plants will not readily grow. The process is 

 cumulative and is often carried so far that nothing but an entirely 

 new plant association can occupy the land and the land lies bare and 

 unproductive for a longer or shorter period while the new association 

 is coming in and getting adjusted. This new association nearly 

 always starts as a scattering growth of aggressive and often unpala- 

 table weeds. 



It is very hard to maintain a balance between the maximum pro- 

 duction of the better forage plants and the maximum number of 

 animals that can be fed upon the area [41]; it is practically impossible 

 to do so upon an open range, where possession is maintained only by 

 having the land overstocked all the time. 



Poisonous plants. — Certain of the plants on the ranges are poison- 

 ous to stock. The natural tendency of the animals to leave such 

 plants alone because they are usually not palatable tends to favor 

 them in their competition with more valuable plants, with the final 

 result that the poisonous plants tend to increase in quantity as time 

 goes on. Under certain circumstances poisonous plants are eaten 

 by the animals (usually for lack of better feed) and serious losses are 

 suffered. (See bibliography, section 9). 



Wild animals. — Besides the domestic stock on a range there are 

 always wild animals, some of which will attack the domestic stock. 

 The extinction of these predatory animals is always an important 

 matter in the range stock business, but when accomplished, it has a 

 reaction which is not altogether desirable. Other wild animals, like 

 prairie dogs and rabbits, that are normally the food of the coyotes, 

 wolves, etc., reproduce rapidly whenever their natural enemies are 

 removed and then they must themselves be removed or they eat up 

 the feed that is needed for the stock. Hence there is a close relation- 

 ship between the stockman's business and the work of the U. S. 



9 The transporting power of flowing water varies as the sixth power of its velocity. Le Conte, Elements 

 of Geology, 5th ed., p. 20, 1903. 



