214 BOTANICAL GAZETTE [MARCH 
so as to give the soil a sufficient water-holding capacity, open places 
in the bull pine forest may permit seedlings of both the species named 
to thrive. Numerous instances of this were noted in the bull pine 
forest under consideration. In places where bull pine had been 
removed there were clumps of young trees of Douglas spruce and 
western larch. If the place is sufficiently open, bull pine seedlings 
are found with the others. It will be seen readily that such a condition 
will lead to a gradual replacement of the bull pine forest by the 
Douglas spruce-western larch combination. There is some evidence 
that such a succession has already taken place, for all around the 
borders of the “sandy pockets” western larch and Douglas spruce 
are more numerous in places than bull pine. There is also reason 
to believe that in the pebbly clay morainic soil around Echo Lake, 
especially to the south and northwest, a more or less pure bull pine 
stand preceded the present stand consisting of a mixture of the three 
species. The bull pines are found in groups, or solitary full-grown 
specimens overtop the younger growths of the next generation of 
Douglas spruce and western larch, these isolated specimens doubtless 
representing all that is left of the former pure bull pine stand. Of 
course this succession has been a gradual one, occupying many gel 
erations, the more successful trees elbowing their way, as it were, 
among the less successful until the spread of the latter is limited by 
their incapacity to adapt themselves to the new environment. All 
stages in this succession are present today in the forest under dis 
cussion, and it was the study of these stages that led to the conclusion 
that has been advanced. 
Out towards Flathead River the zone between the prairie and the 
forest contains a few scattered specimens of bull pine; next to this 
there is a more dense stand of this species with a few scattered trees 
of Douglas spruce; back farther still from the prairie is a zone 
which bull pine is less and Douglas spruce more frequent; and 
finally another condition is found in which western larch joins these 
two species, bull pine being the least conspicuous element of the 
three. Such an arrangement is approximated just west of Echo 
Lake. This region is decidedly morainic in its character, and wher? 
depressions approach the underground water level western Jar 
becomes more numerous, and in places near Echo Lake the surface 
