IAS OF CALIFORNIA]

Differences of climate have largely influenced tree growth and
types in this country. The distribution of tree families is
changing all the time. It shifts just as the climate and other
conditions change. Trees constantly strive among themselves for
control of different localities. For a time one species will
predominate. Then other varieties will appear and displace the
ones already established. The distribution of trees changes very
remarkably from one century to another. For example, in some
sections, the red and black oaks are replacing the white oaks.
Some trees are light-lovers. They require much more sunlight than
others that do well under heavy shade. Oak trees require plenty
of light; maples or beeches thrive on little light.

The seed of trees requiring little light may be scattered in a
dense forest together with that of trees which need plenty of
daylight in order to make normal growth. The seedlings that like
shade will develop under such conditions while those that need
light will pine away and die. Gradually the shade-loving trees
will replace the light-loving trees in such a forest stand. Even
the different trees of the same family often strive with one
another for light and moisture. Each tree differs from every
other one in shape and size. Trees will adapt themselves to the
light and moisture conditions to which they are exposed. A tree
that has access to plenty of moisture and sunlight grows evenly
from the ground to its top with a bushy, wide-spreading crown.
The same tree, if it grows in the shade, will reach a greater
height but will have a small compact crown. Trees run a race in
their rapidity of growth. The winners get the desirable places
in the sunlight and prosper. The losers develop into stunted
trees that often die, due to lack of light exposure. A better
quality of lumber results from tall straight trees than that
produced by the symmetrical, branching trees. That is why every
forester who sets out trees tries to provide conditions which
will make them grow tall and with the smallest possible covering
of branches on the lower part of the trunks.

Where trees are exposed to strong winds, they develop deep and
strong root systems. They produce large and strong trunks that
can bend and resist violent winds which sway and twist them in
every direction. Such trees are much stronger and sturdier than
those that grow in a sheltered forest. The trees that are blown
down i