The new era., 1910-02-10

The nature of a tree. as shown by
its behavior in the forest, is called its
silvicultural character. 1t is made up
of all those qualities upon which the
species as whole, and every individ-
ual tree, depends in it's struggle for
existence. The regions in which a
tree will live, and the places where it
grow with, and these which it kills
or is killed by; it's abundance or scar
city, its size and rate of growth-all
these things are decided by the inborn
qualities, of each particular kind Of
tree.
Different species of trees, like diff
ferent races of men, have special re-
quirements for the things upon which
their life depends. Some races. like
the Eskimos, live only in cold regions.
Others, like the South Sea Islanders,
must have very warm climate to be
comfortable, and are short lived in
any other. So it is with trees, ex-
cept that their different needs are
even more varied and distinct 1t is
always the highest and lowest tenn
perature, rather than the average,
which decides where a tree will or
will not grow. Thus the average tenn
perature Of an island where it never
freezes may be only 60 degrees, while
another place, with an average of
70 degrees, may have occasional frosts
Trees which could not live at all in
the second of these places, on account
of the frost, might flourish in the low
er average warmth of the first.
In this way the bearing of trees to-
ward heat and cold has great deal
to do with their distribution over the
surface of the whole earth. Their dis
tribution within shorter distances also
often depends largely upon 1t. In the
/ United States, for example, the live
Il oak does not grow in Maine, nor the
hcanoe birch in Florida. Even the op-
bosite sides of the same hill may be
covered with two different species,
because one of them resists the late
and early frosts and the fierce midday
heat of summer, while the other re-
quires the GOODNESS and moisture Of
the northern slope. On eastern slopes,
where the sun strikes early in the day,
frosts in the spring and fall are far
more apt to kill the young trees, or
the blossoms and twigs of older ones,
than on those which face to the west
and north, where growth begins later
in the spring, and where rapid thaw-
ing, which does more than the freez-
ing itself, is less likely to take place.
Heat and moisture act together upon
trees in such a way that it is some
times hard to distinguish their effects.
A dry country, or dry slope, is apt
to be hot as we'll, while cool north
ern slope is always moister than one
turned toward the south. Still the re-
suits of the demand of trees for water
can usually be distinguished from the
results of their need of warmth, and it
is found that moisture has almost as
great an influence on the distribution
of trees over the earth as heat itself
Indeed, within any given region it is
apt to be much more conspicuous, and
the smaller the region the more notice
able often is its effect, because the
contrast is more striking. Thus it is
frequently easy to see the difference
between the trees in a swamp and
those on dry hillside near by. when
it would be far less easy to distinguish
the general character of the forest
which includes both swamp and hill
y side from that Of another forest at a