14 



BULLETIN 741, U. S. DEPARTMENT OF AGRICULTURE. 



On the clear-cut lands protected from grazing and where the mor- 

 tality of the reproduction was not abnormally heavy, no new sprouts 

 appeared after two years following clear-cutting (fig 4). On the 

 clear-cut unprotected plots, on the other hand, where a large pro- 

 portion of the sprouts were destroyed by browsing, considerable 

 reproduction was produced not only in the first two seasons but in 

 the third season following cutting, though not subsequently. The 

 removal of practically the entire aerial portion of' the sprouts by 

 browsing prevents the transfer and utilization of the large stores of 



plant food deposited 

 in the elaborate root 

 system of the parent 

 plant, and this nutri- 

 tive material appar- 

 ently tends to stimu- 

 late the production of 

 sprouts in the third 

 season following the 

 removal of the tim- 

 ber. The majority of 

 these third-year 

 sproutswereproduced 

 between 2 and 5 weeks 

 later than those sent 

 up during the first two 

 seasons after cutting, 

 and instead of indi- 

 vidual specimens ap- 

 pearing more or less 

 uniformly over the 

 area, as in the case of 

 sprouts produced dur- 

 ing the first two years, 

 they appeared in 

 bunches of from about 

 3 to 15 specimens. 

 The sprouts produced during the third season distinctly lacked 

 vigor and were, for the most part, killed by frost or other unfavorable 

 climatic factors. Only a very small percentage, even when not injured 

 by inclement weather, possessed sufficient vitality to become perma- 

 nently established. Thus only a sparse, uneven, and weak aspen 

 stand may be expected from sprouts originating on grazed lands dur- 

 ing the third season after cutting, even though grazing is discon- 

 tinued the second year after the timber has been removed. 



_____ Number Of Sprouts Produced Per Season (Protected Area) 



Number Of Sprouts Produced Per Season (Unprotected Area) 



__ Total Number Of Sprouts Remaining (Protected Area) 



_7o/a I Number Of Sprouts Remaining (Unprotected Area) 



Fig, 



4.— Number of sprouts produced on clear-cut aspen plots 

 computed on acreage basis, 1913 to 1916*inclusive. 



