130 BULLETIN 1105, U. S. DEPARTMENT OF AGRICULTURE. 



allowed to accumulate, creates a fire menace, is too well known to re- 

 quire discussion (P). It is also generally recognized that the crop- 

 ping of herbaceous vegetation favors pine reproduction by prevent- 

 ing the suppression of young seedlings. Recent studies described 

 in the chapters on herbaceous vegetation and brush disposal show 

 that competition for moisture by grass and other herbs may be very 

 detrimental to pine reproduction. Proper grazing by cattle and 

 horses can be employed to excellent advantage in subduing this 

 vegetation. Damage to pine seedlings must, however, be rigidly 

 guarded against. In order to secure the maximum benefits from 

 grazing, it must be under control. The distribution of watering 

 places and salting grounds, brush disposal after cutting, and the 

 number of animals on the range must be such that uniform intensity 

 in grazing can be secured. 



The opinion is frequently expressed that grazing assists germina- 

 tion by trampling the seeds into the soil. No direct evidence has 

 been produced in proof of this assertion. It is reasonable to believe 

 that such benefits are realized under certain conditions. On loamy 

 soils the hoofs of cattle, horses, and. sheep may press pine seeds into 

 the soil or make impressions which provide suitable lodging places. 

 On clay soils, however, the benefits of covering the seed may be offset 

 by the packed condition which results from trampling. Frost action, 

 which honeycombs the surface layers of soil in late fall and early 

 spring, is probably more effective in covering seeds than is grazing. 



THE REMEDY FOR SHEEP DAMAGE. 



All investigations on damage to western yellow pine reproduction 

 by grazing in the Southwest agree in the conclusion that sheep are 

 responsible for serious damage. A survey of lands logged under the 

 supervision of the Forest Service on the Coconino and Tusayan 

 National Forests reveals a uniform failure of reproduction, except- 

 ing where seedlings started in large numbers in advance of cutting. 

 This failure is due not to improper methods of cutting or to unus- 

 ually adverse climatic conditions, but primarily to excessive sheep 

 grazing. Data accumulated during the past 10 years show that 

 reproduction can be secured with reasonable certainty under the 

 present method of cutting, provided damage by grazing is eliminated, 

 but that under any silvicultural system in which grazing is inade- 

 quately regulated reproduction is a gamble against overwhelming 

 odds. Although the situation is less critical on other National For- 

 ests, such as the Santa Fe, Carson, Lincoln, Apache, and Sitgreaves, 

 where natural conditions for reproduction are generally favorable, 

 there is evidence that even on these Forests improper sheep grazing 

 may preclude reproduction. 



