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. 
Number Of Sprouts Produced Per Season (Protected Area) 
._ Number Of Sprouts Produced Per Season (Unprotected Area) 
_ ,-— . Total. Number Of Sprouta Remaining (Protected Area) 
Total 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. 
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 maybe 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. 
