EFFECT OF GRAZING UPON" ASPEN" REPRODUCTION. 



23 



Table 10. — Sprouting capacity and height growth of aspen reproduction on clear-cut 



plots. 



Date of examination. 

 \ 



Fall cutting, 1912. 



Number of 



living 



sprouts 



per acre. 



Average 

 height. 



Spring cutting, 1913. 



Number of 



living 



sprouts 



per acre. 



Average 

 height. 



Summer cutting, 1913. 



Number of 



living 



sprouts 



per acre. 



Average 

 height. 



Summer, 1913. 



Fall, 1913 



Spring, 1914... 



Fall, 1914 



Spring, 1915... 



Fall, 1915 



Spring, 1916... 

 Fall, 1916 



Inches. 



41,700 

 32.670 

 34, 700 

 32,810 

 22, 210 

 24, 100 

 21,920 



23.4 

 25.5 

 39.2 

 39.8 

 43.1 



Inches. 



Inches. 



7.3 

 12.5 

 15.5 

 31.4 

 32.5 

 41.2 



50,960 

 44,140 

 43, 850 

 42,730 

 31,070 



16.9 

 20.3 

 34.0 

 34.1 

 46.6 



Table 10 shows that the production of sprouts is heavy on all 

 areas, regardless of season of cutting, and that in general the maximum 

 number of sprouts is in evidence within a season following the removal 

 of the timber. Considering the number of mature, well-developed 

 trees that may occupy the ground, more than enough sprouts are 

 produced on the respective plots regardless of season of timber 

 removal. The most vigorous sprouting occurred on the plot the 

 timber of which was removed in the spring, and the least vigorous on 

 the autumn-cut plot. On the spring-cut plot, however, the death 

 rate of sprouts was greatest. The rate of growth was relatively 

 uniform and approximately the same on each plot, and the annual 

 increment averaged about 15 inches, the height growth being practi- 

 cally the same from season to season. 



From the above facts it may be concluded that (a) regardless of 

 season of cutting a sufficient number of aspen sprouts is produced 

 on clear-cut lands to restock the lands fully, provided grazing is 

 properly controlled; and that (b) in general the reproduction will 

 have attained sufficient height by the end of the third, year of growth 

 to be exempt from destructive browsing by sheep, and by the end of 

 the fourth, or more certainly the fifth year, to be out of danger from 

 cattle. 



SILVICULTURAL MANAGEMENT OF ASPEN. 



METHODS OF CUTTING. 



Experimental evidence gathered from variously treated plots 

 points to the fact that if the lands are to be devoted permanently to 

 the production of aspen, clear-cutting or repeated heavy thinnings 

 are the best means by which to secure vigorous sprouting and an 

 evenly distributed stand. 



As is shown by the sparse stand of sprouts on the plots established 

 in the standing timber, aspen is practically unable to reproduce 



