48 ECONOMIC MAMMALOGY 



Sheep, and especially goats, deer, elk and moose browse extensively 

 upon shrubs and young trees and the lower branches of larger trees. 

 This may be a good thing where it is desirable to keep the forest floor 

 free from undergrowth or to clear brush land in order to give grass for 

 pasturage a chance. Indeed, goats have been deliberately used for 

 those very purposes. On the other hand, browsing animals may be very 

 harmful to attempts to reforest burnt-over or cut-over land, or may 

 prevent the natural or artificial replacement of dying trees within the 

 forest, by destroying the young trees or nipping the tops off before they 

 get tall enough to be out of reach. 9 Cattle and horses where land is 

 much over-grazed and herbage scarce, also browse to some extent, but 

 they are not natural browsers, as goats and the members of the deer 

 family are. 



Only a short time ago newspapers and magazines had much to say 

 about the efforts to drive many of the deer from Kaibab Forest, Ari- 

 zona, to other ground, because the range in the forest was overgrazed 

 and overbrowsed and the deer were in danger of starving, and good 

 photographs were published showing the condition of the browsed 

 aspens. The "plimsoll" line, or line parallel with the water level, to 

 which cedars are supposed to have been trimmed from below by deer 

 along certain lakeshores in the Adirondacks, is the subject of some 

 recent interesting discussion. 10 



In addition to interference with reforestation and replacement of 

 forest trees, and the destruction of the natural forage for livestock, 

 overbrowsing and overgrazing has another disastrous effect upon prop- 

 erty. The vegetative cover (including trees, shrubs, grasses and other 

 plants) serves to break the force of rainfall and the run-off of storm 

 water, and to bind the soil together, thus retarding or preventing ero- 

 sion. When this cover is destroyed by too much browsing or grazing, 

 or by fire or any other cause, and perhaps the soil is loosened by the 

 trampling of cattle, sheep and other animals, erosion is accelerated on 

 all steep slopes. As a result, sometimes entire hill or mountain sides are 

 denuded of their soil, nothing being left but barren rocks upon which 



9 Colville, Effect of grazing upon aspen reforestation, U. S. Dept. Agric. Bull. 

 No. 741, 1919; U. S. Division of Forestry Bull. No. 15, 1898. Adams, Scientific 

 Monthly, xx, 561, 589, 593, 1925. See also Adams, The economic and social importance 

 of animals in forestry, with special reference to wild life, Roosevelt Wild Life Bull, 

 m , 539, 676, 1926. 



10 Merriam, Mammals of the Adirondack Region, pp. iio-m, 1886. Johnson, On 

 the supposed relation of deer to cedars bordering certain Adirondack lakes, Journ. 

 Mammalogy, vin, 213-221, 1927. Burnham, The plimsoll line in white cedars, ibid., ix, 

 43-47, 1928. 



