EFFECT OF GRAZING ON WESTERN YELLOW PINE. 25 



(10) The effect of grazing upon the height growth of reproduc- 

 tion is marked. Severely injured trees grow only from one-half to 

 one- third as fast as uninjured trees. 



(11) Grazing injuries are not responsible for the common deformi- 

 ties of mature trees. 



(12) The permanent effects of grazing injuries upon the develop- 

 ment of the trees damaged are not serious, provided the damaged 

 trees have a chance to recuperate. If grazing is unrestricted, about 

 15 per cent of the total stand is likely to be killed during the period 

 required for reproduction to become established. • 



(13) Reproduction that has been impoverished greatly by grazing 

 is more likely to be attacked by some fungi and insects than unin- 

 jured and vigorous reproduction. However, the ordinary grazing 

 injuries are not believed to increase seriously the danger of such 

 attacks. 



APPLICATION OF RESULTS TO RANGE MANAGEMENT IN THE 



SOUTHWEST. 



The conclusions arrived at in this study are believed to be appli- 

 cable over the entire yellow-pine type of the Southwest. Since for- 

 age composition, class of stock using a range, intensity of grazing, 

 and methods of handling stock vary on different Forests, it is not 

 advisable to attempt to prescribe specific suggestions for certain areas, 

 but rather to prescribe definite remedies for certain conditions. 



Under present conditions all reproduction should be protected 

 against severe damage by grazing. Where immediate cutting of the 

 mature stand is contemplated, the reason for protection is obvious, 

 since the prime purpose should be to insure a stand of reproduction. 

 Where reproduction on an area not to be cut over in the near future 

 is being injured, protection is needed to assist nature in maintaining 

 a forest cover. Reproduction generally occurs naturally in openings 

 made by the death of mature trees. Unless this reproduction is pro- 

 tected, the gaps will tend to increase and the regeneration of the 

 forest be made constantly more difficult. Moreover, under the most 

 favorable conditions it is only through the combination of a good 

 seed year with two or more good growing years following that any 

 considerable amount of reproduction becomes established. Such a 

 combination is so rare that it is not safe to depend upon it. 



The grazing of stock on National Forests must be so regulated that 

 the number of stock shall not decrease, but, if possible, shall increase. 

 Under proper grazing management reproduction does not suffer an 

 unwarranted amount of damage ; in fact, the advantages of conserva- 

 tive grazing in reducing the loss of reproduction by fire probably 

 offset the injury from stock. The application of conservative graz- 

 ing throughout the western yellow-pine type, then, is the basis for 

 the protective recommendations which follow. 



