ASPEN REPRODUCTION AND MANAGEMENT 393 



VEGETATIVE REPRODUCTION 



To maintain the density of the stands generation after generation in 

 their wide distribution, it is evident from the preceding discussion that 

 the vegetative reproduction must be of exceptional vigor and per- 

 sistence. 



The investigations under way at the Experiment Station show that 

 while sprouting is more vigorous under some circumstances than 

 others, stands of any age may be clear-cut at any season of the year 

 and still sprout with sufficient vigor to fully regenerate the stand. The 

 vast majority of sprouts come up as suckers from horizontal roots 

 lying near the surface, a much smaller number come from the root 

 collars, and a still smaller number from the stump itself. Rather 

 frequently sprouts are found coming from old groups of sprouts which 

 have originally been root suckers. Prior to the cutting of the parent 

 stand, sprouts arose in these places year after year, existed a season 

 or two, and then died from suppression. Under these conditions a 

 knot of old sprout "stumps" and new buds are finally formed which 

 may attain a diameter of 2 to 3 inches. These always give rise to 

 numerous sprouts when the stand is cut. An examination of 5,417 

 sprouts on one of the areas which was clear-cut to study the sprout re- 

 production shows 83 per cent to be root suckers, 9 per cent originating 

 in old sprout groups which are really suckers as well, 7 per cent 

 originating at the root collar, and i per cent on the stump itself. On 

 three other plots where old groups were included with those originat- 

 ing directly from the roots, the root-sucker class comprised 89.5 j)er 

 cent, the root-collar class 10 per cent, and the stump class 0.5 per cent 

 in a total of 1,307 sprouts examined. 



Effect of Cutting at Different Seasons 



In the case of eastern hardwoods, one of the most important factors 

 which influences regeneration by sprouts is the season of cutting the 

 parent stand.* Summer cutting as a rule results in an immediate pro- 

 duction of sprouts, which remain tender to the end of the growing sea- 

 son and are killed by the first heavy frosts. Aspen in the intermoun- 

 tain region, however, does not respond immediately after cutting. l)ut 

 delays the maximum sprouting. In the case of fall cuttings the sprouts 

 come up during tlu" year following, as is usual. When cuttings are 



* Graves, H. S. "Principles of Ilaiulling Woodlands." 17.?. 191 1. 



