7S 
FOURTEENTH REPORT. 
villa loniccra as shown in Plate 18. These two species are the most 
abundantly represented in the different stations of this region but 
other species may assume greater importance in some of the stations, 
e. g., Rhus glabra, Gaylussacia baccata, V actinium p ennsy Ivamcum, 
Taccinium canaclensc , GauWieria procumbens , Anaphalis margaritacea , 
Gnaphalium decurrens, Hieratium venosum , Panicum xantTwphysvm , 
etc. A number of other species may also be present which add to the 
list without greatly affecting the general appearance. 
As mentioned above this association is usually immediately preceded 
by the fireweed association. In general it does not follow the bramble 
association unless that is very open because aspen seedlings require 
a maximum of light which is not obtained when the brambles are at 
all dense. As the aspens are very intolerant of shade* unless they 
obtain their start first they will be killed out. As the aspens seed 
early in the spring and grow very rapidly for the first few years they 
obtain a maximum of light for years. This same intolerance of shade, 
however, shortens the life of the association, for the aspen seedlings, 
tho produced in large numbers can not develop without virtually the 
maximum of light and consequently must wait for openings in the 
aspens befor this can be obtained. Meanwhile other tree seedlings that 
are more tolerant are developing in the spaces between the aspens. This 
makes reproduction more difficult for aspen seedlings. As these other 
trees grow higher and higher they come to overtop the aspens and shut 
out light. The aspens, which are not normally long-lived trees even 
under the best of conditions, cannot withstand this and with their 
death the station is left in possession of the succeding association. 
Should another fire come befor this succession has completely taken 
place, the aspen association is rejuvenated and the work of succession 
recommences. 
The pertinent facts of succession into areas occupied by this associa- 
tion hav alredy been stated in connection with the different associations, 
but will be summed up here from the aspen standpoint. The great 
part of the area now occupied by the aspen association was formerly 
pine land. That it will again be pine, providing no serious accidents 
occur, is evident from the following pertinent facts. Scattered here 
and there in the aspens are seeding trees of pine, particularly Pinas 
resinosa , while in the aspens themselves are many seedlings of pines— 
Pinus resinosa and Pinas strobus — of different stages in development 
but all vigorous in appearance, as shown in Plate 19. The number is 
sufficiently great to produce a fair stand of pine as soon as the young- 
trees can grow, provided fire is kept out. The great quantity of Pteris 
aquilina would point towards a tendency for the aspens to be succeded 
by oak woods such as is the case in many places in Michigan, Illinois, 
and Wisconsin. Oaks are represented in the region by several matur 
trees and numbers of seedlings, occuring isolated from one another 
and nowhere giving present indication of assuming the character of 
an association. Where oaks are present they are not infrequently 
associated with pine seedlings. Furthermore the region is nearly at 
the northern limit of the genus Quercus, so taken all in all it appears 
*VVeigle, W. G. & Frothinghain, E. H. The Aspens: Their Growth and Management. U. S. 
Dept, of Agr. Forest Service, Bull. 93, May 1911. 
