148 BOTANICAL GAZETTE [ FEBRUARY 
mon occurrence beneath the older white pine in sufficient numbers to 
indicate an eventually mixed stand should they persist. 
In the discussion of succession on abandoned fields it has been 
shown that white pine is gradually regaining control of the areas on 
which it was once dominant, by the direct reseeding leading to the 
establishment of pure stands, indirectly by the supplanting of white 
birch stands, and, were human interference withdrawn, by the replace- 
ment of pitch pine stands. 
I have employed the month of vacation for the past six years in 
the study of the sand plain vegetation. Forty-five permanent sample 
plots in the stands, representing various stages of succession, have 
been established and mapped, and those have been given above which 
in my judgment best represent the conditions discussed. Most of 
these plots will be kept under observation in the future, so that definite 
records of the changes in situ may be recorded. Besides these, the 
character of the vegetation has been recorded by too list charts. _ 
While investigations have been conducted in the effort to determine 
what changes in ecological conditions have brought about the changes 
in vegetation on the sand plains, I feel that they have not progressed 
far enough to justify their publication. Therefore it seemed best to 
make the present paper simply a record of succession. The nomen- 
clature is that of Gray’s New manual of botany. 
Summary 
Pitch pine succeeded to the control of areas from which the dom 
nant white pine had been removed. 
White pine, however, is gradually regaining its control on cut-over 
areas, as well as on abandoned fields, by its actual replacement of 
white birch stands and by its probable displacement of the pitch pine 
stands. ; 
The work upon this paper was begun at the suggestion of Dr. L. R. 
Jones of the University of Vermont and was continued under Dr. 
H. C. Cowres of the University of Chicago. I wish to express my 
appreciation of the kindly criticism and encouragement received from 
them. 
UNIVERSITY OF TORONTO 
