FOURTEENTH REPORT. 
1 1 . Towards the margins and along the roads they become more numer- 
ous and varied and the small tree, Acer pemisylvaivieum, often assumes 
considerable importance. In openings, however, whether brot about 
naturally by the fall of a large tree or otherwise by fire, clearing, etc., 
so that light is admitted to the ground, a very varied growth follows 
which may often be rather rich in number of species. This is more 
likely to be the case on the clayey rather than on the sandy soils, such 
as one finds northwest of Burt Lake. A number of plants are found 
in such localities, which, tho typical of hardwood areas farther south 
even on poorer ground, are not usually found in the hardwood on the 
sandy ground which it usually occupies in this region. A number of 
such species are Filix hudbifera, Allium tricoccwm . Hystrix patula, 
I otaea alba , Adiantum pedatum, Aviso ema triphylliom, Caulophylluin 
thalictroidcn, Circaea intermedia Frularia grandiflora , Osmunda clay- 
toniana and Viola scabriuscula. 
Ages ago this association came into possession of the ground which 
it occupies at the present time. Now it is supreme and self perpetuating 
in the land il occupies and holds its own, year after year, even in spite 
of some slashing, unless severe tire runs thru its territory and burns 
the humus out of the ground. This causes a recommencement of the 
series of successions. This may or again it may not lead back to the 
beech-maple. This association, which is climatically dominant over the 
north central states which includes Wisconsin, Mich., 111.. Indiana and 
Ohio, is dominant in this region only when the soil is favorable. All 
the evidence which is at hand shows that the boundaries of the hardwood 
areas are gradually being drawn in rather than expanding in extent. 
It is true, however, that man and especially the coming of lire have been 
very instrumental in bringing this about. The seedling hardwoods do 
very well in hardwood soil when they have sufficient light. In the 
vicinity of hardwood areas there are great numbers of seeds scattered 
in the aspens which are growing on pine land. Many of these germinate 
especially during wet springs, but very few live out the summer. Those 
that do and continue to eke out an existence are dwarft and stunted 
and it is quite obvious that they are with difficulty holding their own. 
As this is otherwise in the case of the aspens and the pine seedlings 
in them, it is obvious that there is no succession going on at the present 
time from the conifer type to the hardwood type. This region is part 
of the tension zone between the conifer province and the deciduous 
forest province, and. in view of the fact that invading associations of the 
same tvpe of vegetations must be able to displace those already occupy- 
ing the ground, it is easily seen that the association holding the ground 
can withstand the inroads of the invading association except under 
the best conditions for those associations. Accordingly the pine — repre- 
sented by aspens at the present time — will occupy all of the land from 
which the hardwood is excluded because of the fact that the margin 
of suitability of the soil is not sufficiently high. That before the advent 
of lumbering the genetic conditions were such as one would expect to 
find in this part of Michigan,* namely that the hardwoods were grad- 
uallv displacing the pines, is evidenced in the region north of North 
Fishtail Bay. Altho this station is characteristically hardwood there 
*Whitfo d. H. X. The Genetic Development of the Forest in Northern Michigan. Bot. Gaz. 31: 
289-325. May 1901. 
