Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1904-11-12
HOW FORESTS GROW
THERE ARE TWO GREAT TYPES.
THE PURE AND MIXED.


where Tree. of Different Habits
The laws which govern the distribu
/ ton of trees produce the two great
types, the pure and the mixed forest
i The former is the result of local con
ditions which trees of one kind only
can survive.
| In the North woods the balsam Oc-
cupies the swamps, usually to the ex-
clusion. OF all competitors, since no
other OF the native trees can thrive In
wet places. In the Black Hills and
other parts or the middle west the
small demands OF the bull pine upon
moisture enable 1t to form pure woods
On a soil too dry TO support other M
tive trees. The jack pine of the New
Jersey barrens and the long leaf pine
OF the southern states grow in pure
or nearly pure stands since they alone
can Withstand the peculiar conditions
OF these regions.
Where climate and soil are favorable
to various trees we find the mixed for
est. the number Of species in mixture
| depending upon the suitability Of the
locality to forest growth.
Upon the hardwood flats OF the Adj
rondacks the hard maple, the yellow
birch and the beech are the only de-
ciduous trees able to Withstand the Sc
we're climate. In the southern Appa-
lachian forests. where the trees OF the
north and south meet under conditions
favorable TO both, we find more than
100 different kinds.
The distribution OF trees. therefore,
is the joint result of local conditions
and OF the individual and varying re-
quircments of the different species up
on moisture, soil and climate. The
laws. however, which govern forest dis
tribution are not identical with those
which regulate the behavior OF trees
in mixture. They do not explain why
each species, IL undisturbed. maintains
the same proportion in the mixed for
est. Why does not the hard maple
drive out its competitors in the Adiron-
dacks. the oak gain the upper hand in
the forests of the southern Appala-
chians, the red fir eXterminate the
western hemlock on the Pacific slope:
Wherever mixed forest occurs
on. Let us see how tie combatants
are armed and why the representation
of each species remains unchanged.
The more important of the character
istics which affect tie capacity of Il
tree to hold its own in mixture with
trees of other kinds are its demands
upon light. its rate of growth ana its
power of reproduction. No two species
require an equal amount of light. grow
at the same rate or are Identical in
their capacity TO reproduce themselves.
The endowment of each, with habits
differing from those of its neighDors,
but with strength and weakness SO
balanced that all which occur in mix
ture enter the struggle for existence
upon an equal footing, is one of the
marvellous feats of nature.
The red spruce of the North woods,
through its ability to endure dense
shade. has been given the power TO
hold its own against faster growing
competitors, some of which exceed it
greatly in their capacity to reproduce
themselves. The young spruces which
spring up here and there throughout
the forest struggle along under the
n tree making more insistent demands
upon light could not survive.
In the forests OF the southern APP
palachians the oak is in many localities
the characteristic tree. Growing rap
idly and exceedingly hardy, it might be
expected TO increase steadily its pro-
portion in the mixture. The equilibri-
um is maintained through the fact that
the oak can endure but little shade
and that its seed is heavy, limiting its
reproduction to the immediate vicinity
Of the parent tree.
In the same region the yellow poplar
and the chestnut, both trees which
grow rapidly and are capable of endur-
ing considerable shade. are controlled,
the one because much OF its seed is
barren, the other because many of the
nuts are eaten by animals. And the
red cedar, OF slow growth and sparse
representation, Is aided through the
distribution of fits seeds by birds, with
their power to terminate uniInpaired-
The aspen. short lived and requiring
much light, holds its own with longer
lived and shade enduring trees because
its downy seed is produced in great |
quantities and IS scattered far and |
wide by the wind. The ash and the |
Eastwood. of rapid growth and bearing |
an abundance OF seed. are withheld by |
strong demands upon light and by the |
seed OF fresh and fertile soil. The |
red fir. equaled by few North American !
trees in rapidity of growth and other |
wise well equipped TO gain the upper |
hand In its region. Is controlled through |
the usual failure OF its seed to germi- |
nate except when accident has remoy-
ed the leaf litter and exposed the min
eral soil
The study of trees as living. striving |
organisms in world of their own
leads an almost human interest in the /
forest. Every day spent in the woods |
will be the pleasanter for some insight /
gained into what is going on within it. i
and an earnest observer can gain
of practical value by an at