UNITED STATES DEPARTMENT OF AGRICULTURE 



I BULLETIN No. 738 



Contribution from the Fopest Service 

 HENRY S t GRAVES, Forester 



Washington, P, C, 



PROFESSIONAL PAPER 



December 19, 1918 



EFFECT OF GRAZING UPON WESTERN YELLOW 

 PINE REPRODUCTION IN CENTRAL IDAHO. 



By W. N. Sparhawk, Forest Examiner. 



CONTENTS. 



Page. 



Timber and live stock 1 



Studies made on three grazing allotments — 2 



The Deadwood allotment 3 



The Silver Creek allotment 4 



The South Fork allotment 5 



Method of study 5 



Injuries to reproduction caused by sheep 



grazing 6 



Nature of injuries 6 



Amount of damage 7 



Sizes injured 12 



Season of injury 14 



Relation between amount of damage and 



intensity of grazing 15 



Cumulative effect of grazing 18 



Relation between amount of damage and 



amount and character of forage 19 



Page. 

 Comparison of the damage caused by 



sheep and other agencies 19 



Valuation of damage 22 



Benefits of sheep grazing to the forest 25 



Aid to reproduction 25 



Protection against fire 27 



Management of grazing 27 



Time to graze 27 



Intensity of grazing ' 28 



Methods of handling 28 



Herding 28 



Driveways ' 29 



Salting 29 



Watering 30 



Bedding 30 



TIMBER AND LIVE STOCK. 



The western yellow pine forest is the most important source of 

 timber in the area drained by the Columbia River and its tributaries 

 east of the Cascades and north of the Snake River Valley. There 

 are estimated to be approximately 7 million acres of western yellow 

 pine (Pinus ponderosa) in the National Forests of this region, and 

 there is probably an equal area outside the Forests. A conservative 

 estimate of the National Forest stand is 50 billion board feet. At a 

 growth rate of 100 board feet per acre per year 1 the western yellow 

 pine land within the National Forests alone is capable of producing 

 a sustained yield of 700 million board feet of lumber every year. 

 A considerable portion of the timberland now in private ownership 



1 See U. S. Department of Agriculture Bulletin 418, "Western Yellow Pine in Oregon," by T. T, Munger, 



7535^1 s~Bun, 738— i 



