10 



BULLETIN 741, U. S. DEPARTMENT OP AGRICI/LTTJRE. 



controlled cattle grazing, such as has been carried out in the vicinity 

 of these plots, and the perpetuation of the aspen stand are not neces- 

 sarily antagonistic. 



The young, tender aspen shoots are browsed more or less by cattle, 

 however, and the damage inflicted may increase in proportion to the 

 density of the reproduction. Hence, where sprouts are produced in 

 sufficient numbers to attract stock and accustom the animals to 

 browse upon aspen, a greater per cent of damage may occur than 

 where the stand of sprouts is sparse, as in standing timber. A 

 maximum number of sprouts invariably follows clear-cutting, and 

 accordingly the extent of injury by grazing to dense stands of repro- 

 duction can best be determined on clear-cut plots. 



Table 6. — Total number of sprouts the laterals and terminals of which were removed by 

 cattle browsing^ on plots in standing timber; data grouped according to intensity of 

 grazing and height classes. 





Lightly grazed. 



Moderately grazed. 



Season and height class. 



Total 

 number 

 sprouts. 



Number 

 browsed. 



Per cent 

 browsed. 



Total 

 number 

 sprouts. 



Number 

 browsed. 



Per cent 

 browsed. 



1915 



150 

 166 



31 

 99 

 40 

 31 







379 

 311 



41 

 83 



78 

 52 



3 

 13 



2 

 2 

 2 

 1 



0.78 



1916 



5 



3.2 



4.20 



Height class: 



4.87 









2.41 



2.5 feet to 3.5 feet 







2.56 









1.92 













Heavily grazed. 



All intensities of 

 grazing. 



Season and height class. 



Total 

 number 

 sprouts. 



Number 

 browsed. 



Per cent 

 browsed. 



Total 

 number 

 sprouts. 



Per cent 

 browsed. 



1915 



40 

 36 



6 

 15 



7 

 4 



7 

 13 



17.50 

 36.10 



10 

 31 



2 

 6 

 2 

 1 



1.75 



1916 



6.20 



Height class: 



2.60 



1.5 feet to 2.5 feet 



4 



26.60 



3.20 



2.5 feet to 3.5 feet 





3.5 feet to 4.5 feet 







1.60 













INJURY TO ASPEN REPRODUCTION BY GRAZING ON CLEAR-CUT LANDS. 



EFFECT OF SHEEP BROWSING. 



Because of the high mortality due to natural causes the most 

 authentic data showing the effect of grazing on the stand and the 

 condition of the sprouts can probably be obtained by comparing the 

 stands on similar fenced and unfenced clear-cut plots. Four plots 

 were selected on typical aspen range and clear-cut in the fall of 1912; 

 two of these were fenced against stock and the other two left unfenced. 



The data recorded on the two sets of plots are summarized in 

 figures 2 and 3. Figure 2 shows for each season during which the 

 observations were made (1) the rate of sprout production on normal 



