EFFECT OF GRAZING UPON ASPEN REPRODUCTION 207 



very serious where the stock was properly handled. The damage 

 was never so great as that caused by sheep. 

 As on sheep range, so on cattle range the extent of injury 



Fig. 69. — CLEAR-CUT ASPEN LAND PROTECTED FROM SHEEP GRAZING. 



Under such conditions as many as 100,000 sprouts to the acre are not uncommonly produced. 



(See Fig. 68.) 



varies directly with the closeness of the grazing. The injury is 

 less, indeed practically nominal, on lightly or moderately cropped 

 areas, and relatively heavy (17.5 per cent in 1915 and 36.1 per 

 cent in 191 6) on very heavily grazed areas. Thrifty aspen repro- 

 duction of varying size and age is found practically throughout 

 the aspen type where the cover is extensive and where there has 

 been moderate grazing for a number of years by cattle only. 

 This is by no means true of most sheep range in the aspen type. 

 Where only a small amount of aspen occurs on the range, as along 



