UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 741 SUMS, 



Contribution from the Forest Service 

 HENRY S. GRAVES, Forester 



&JV&.TU 



Washington, D. C. 



PROFESSIONAL PAPER 



February 7, 1919 



EFFECT OF GRAZING UPON ASPEN REPRODUCTION. 



By Arthur W. Sampson, Plant Ecologist. 



CONTENTS. 



Page. 



Purpose 1 



Method 2 



Injury to aspen reproduction by live stock in 



standing timber 3 



Effect of sheep browsing 3 



Relation between intensity of grazing 



and injury to sprouts. . . •. 5 



Relation between intensity of grazing 

 and injury to sprouts of different 



height classes 7 



Summary 8 



Effect of cattle browsing 9 



Injury to aspen reproduction by grazing on 



clear-cut lands 10 



Effect of sheep browsing 10 



Injury to aspen reproduction— Continued. 



Effect of cattle browsing 15 



Comparative injury to aspen sprouts by sheep 



and cattle 16 



Height at which reproduction is exempt from 



grazing injuries 18 



Height to which sheep browse 18 



Height to which cattle browse 21 



Rate of growth of aspen reproduction 21 



Silvicultural management of aspen 23 



Methods of cutting 23 



Methods of brush disposal 24 



Summary 25 



Recommendations 27 



PURPOSE. 



It is desirable that on lands bearing a stand of aspen {Populus 

 tremuloides) 1 a proper balance be maintained between timber 

 production and grazing. In many of the National Forests, particu- 

 larly those in northern New Mexico and Arizona, in Colorado and 

 Utah, and in portions of Idaho and Nevada, aspen is a tree of con- 

 siderable commercial value. It is used chiefly for fuel, posts, corral 

 poles, lumber, boxwood, excelsior, and mine props, and the demand 

 for it is steadily increasing. As a protective cover for watersheds, 

 aspen, by reason of its extensive lateral root system, is probably more 

 valuable than any other tree species with which it commonly is found. 



1 Some taxonomists claim that the proper title of the western aspen is Populus aurea Tidestrom 

 being distinguished from the more eastern Populus tremuloides Michaux by certain technical differences 

 in the flowers and fruit, as well as by the fact that after frost the leaves of the former take on a golden- 

 orange rather than a light-yellow hue. Without entering into the merits of the question, the present 

 usage of the Forest Service is here adhered to. 

 76783°— 19— Bull. 741 1 



