THE EFFECTS OF GRAZING 285 



largely eliminates forage, the use of the forest for grazing 

 purposes on a large scale is less universal. In regions such 

 as the west coast of Washington and Oregon, with climatic 

 conditions favorable to the development of dense forests, 

 there is very httle forage to be found under the heavy 

 forest canopy. 



The Effects of Grazing. — All forests are not equally sus- 

 ceptible to injuries from grazing. Hardwood forests are more 

 easily injured by browsing but recover better than do conifers. 

 Due to the fact that the animals prefer to browse upon hard- 

 woods, grazing usually favors conifers as contrasted to hard- 

 woods in mixed stands. 



Shallow rooted species are likely to receive more injury 

 through trampling than deep rooted trees. 



The effects of grazing may be subdivided into : 



Effect upon the soil. 



Effect upon reproduction. 



Effect upon trees past the reproduction stage. 



Effect upon the control and prevention of forest fires. 



Efect Upon the Soil. — The physical condition of the soil 

 is injured by the trampling of the animals which compacts 

 and hardens the soil. Erosion is often started on steep slopes 

 and on other lands where the ground cover is closely browsed 

 or destroyed. Trampling, particularly by animals with sharp 

 hoofs, has a loosening and cutting effect upon the surface of 

 the soil which may be washed away in succeeding rains. 

 Grazing as a cause of erosion is of great importance in the 

 western half of the United States, as indicated by the follow- 

 ing quotation from Sampson and Weyl-: "Serious erosion on 

 western range lands is due chiefly to the destruction of the 

 vegetation as a result of overgrazing and mismanagement of- 

 live stock." 



