APPLIED ECOLOGY 



323 



forage provided by each of the communities and of how they may 

 be controlled or modified to advantage. Only suggestions of the 

 nature of the research on these problems can be given here, but 

 they should indicate the degree to which ecology is contributing 

 to the solution of range problems. 



FlG. 172. To permit grazing to continue until range is entirely depleted 

 and gullying has reached such extremes is obvious mismanagement, but it 

 happens all too frequently. Note absence of gullies under protection of oak 

 tree.— U. S. Forest Service. 



The seasonal variations of major species have been studied in 

 terms of grazing value. Competitive relationships of grasses and 

 forbs (associated herbs) have been investigated as well as their 

 relative palatability. The effects of grazing on community struc- 

 ture have been given much attention, particularly with regard to 

 criteria for the recognition of excessive use and the time and con- 

 ditions necessary for recovery to normal. As a result, the carrying 

 capacity of many forage types is well known, even for different 

 seasons of the year. With regard to range condition and carrying 

 capacity, the effects of rodents have been studied as well as the 

 effects of predators upon the rodents. Effects of drought have 

 been given much attention as well as the rates with which ranges 

 recover from drought, and, in this connection, the water require- 

 ments of important individual species have been determined. In 



