2 BULLETIN 738, U. S. DEPARTMENT OF AGRICULTURE. 



will probably be devoted eventually to other use, but much of it is 

 more valuable for the continued production of timber than for any 

 other purpose, so that it is reasonable to expect a total annual incre- 

 ment of at least a billion board feet on National Forest and privately 

 owned land now occupied by western yellow pine. In this region 

 growth is rapid, the quality of lumber produced is excellent, abun- 

 dant natural reproduction follows logging, and the greater part of 

 the area is accessible and fairly easy to log. The perpetuation of 

 the western yellow pine stand therefore insures the continuation of 

 an important part of the lumber industry in the Northwest. 



Because of the small rainfall over mosf of the untimbered part of 

 the region and the consequent dependence of the rapidly developing 

 agricultural industry upon irrigation, the maintenance of a forest 

 cover in the mountains is as desirable for regulation of stream flow 

 as for the production of timber. 



The live-stock industry is important throughout this region, and 

 the greater part of the forest area is utilized as spring or summer 

 range for sheep and cattle. Although the quality of forage in 

 western yellow pine stands varies widely, there are no areas which 

 do not contain at least a small amount of palatable feed. Allowing 

 even the very liberal average of 7 acres per sheep or 35 acres per 

 cow — a large part of it has at least double this capacity — the western 

 yellow pine type in the region described will supply summer range 

 for a million sheep or 200,000 cattle. 



The utilization of this forage, particularly on areas suited to sheep 

 rather than to cattle, has presented a somewhat difficult problem, 

 owing to the serious damage done by sheep to forest reproduction 

 under the methods of handling hitherto prevalent and to the resulting 

 idea common among silviculturists that sheep grazing and forest 

 production can not be carried on together. To determine just how 

 much harm is done to forest reproduction by sheep and how far 

 this damage can be reduced by more careful use of the range, an 

 intensive study was made on the Payette National Forest in central 

 Idaho during the years 1912 to 1914, inclusive. It is believed that 

 the results of this study, which are presented in the following pages, 

 are fairly applicable to the entire region described: 



STUDIES MADE ON THREE GRAZING ALLOTMENTS. 



The effect of sheep grazing upon conifer reproduction was studied 

 on a number of small sample plots well distributed over three sepa- 

 rate grazing allotments. The study was carried on for three years 

 on two allotments, one on Deadwood River and the other on Silver 

 Creek, a tributary of the Middle Fork of the Payette River. In 

 the third year, 1914, a third allotment, on the South Fork of the 

 Payette, was also studied. 



