The Washington times., 1901-07-07
GROWTH OF FOREST TREES
Some Interesting Facts Regarding
Their Development.
How They breathe and Absorb sus-
tenance-MnteriaIs Upon Which
They Feed-The Annual Rings by
Which Age May BE ReckOncd.


They Fced-The Annual Rings by
Which Age May BE Reckoned.
The forest is the most highly organ
lied feature of the vegetable world. 1t
takes its Importance less from the in
dividual trees which help to form it
than from the qualities which belong
to it as a whole. Although it is COM
posed of trees, the forest is far more
than a collection of trees standing in one
place. Ii has a population of animals
and plants peculiar to itself, soil
largely of its own making, and 4 eli
mate different in many ways from that
of the open country. Its influence upon
the streams alone makes farming posi-
BILE in many regions, and everywhere II
tends to prevent floods and drought.
1t supplies fuel, one Of the first neces-
| saries of life, and lumber, the raw ma
terial without which cities, railroads,
| and all the great achievements of ma
terial progress would have been either
long delayed or wholly impossible. The
forest is as beautiful as il is useful.
No one can really know the forest
without feeling the gentle influence of
one of the kindliest and strongest parts
of nature. From every point OF view it
| is one of the most helpful friends Of
man. Perhaps no other natural agent
has done so much for the human race
| and has been Sc recklessly used and so
little understood.
THE PARTS OF A TREE.
A tree is a woody plant, growing up
from the ground usually with a single
stem. 1t consists of three parts; the
roots. which extend into the ground TO
a depth of three or four feet, or still
farther when the soil is not too hard
and they do not find moisture enough
near the surface. They hold the tree in
place, and take up from the soil water
and certain mineral substances which
the tree needs in its growth. Next
there is the trunk, stem, or bole, which
supports the crown and supplies it with
mineral food and water from the roots.
Finally, the crown itself, with its net
work of branches, buds, and leaves, in
which the food taken up by the tree
from the soil and air is worked over
and made ready to assist in the growth
of the whole plant. The crown has
more to do with the life Of tree than
its other parts, for the most important
processes in the reproduction of the
tree and the diges don Of its food take
place in the crown. For this reason,
and because we can control its shape
and size more easily and directly than
that of the roots or trunk, it is Of spe-
cial interest 10 the forester.
THE FOOD OF A TREE.
The materials upon which d tree feeds
are derived from the soil and air. The
minute root hairs which spring from
the rootlets take up water from the
ground, and with it various substances
which it holds in solution. These are
the earthly constituents of the tree.
which reappear in the form of ashes
when any part of it is burned. The
water which contains these materials
gees straight from the roots to the
leaves, in which a most important pro-
cess in the feeding OF the tree takes
place. This process is the assimilation
or taking up and breaking up, by the
leaves, of carbonic acid gas from the
air. 1t goes on only in the presence of
light and heat, and through the action
of chlorophyll, a substance from which
the leaves and the young bark get their
green color.
Plants containing chlorophyu are the
chief means by which mineral ma
terials are changed into food, so that
nearly all plant and animal life depends
upon them. Plant cells which contain
chlorophyl break up the carbonic acid
gas with which they come in contact,
retain the carbon, one of its elements,
and send back the other, oxygen, into
the air. Then, still under the influence
of the sunlight, they combine the car
bon with the oxygen and hydrogen Of
the water (water being composed of
two parts Of hydrogen to one part of
oxygen) from the roots into new chem
ical compounds, in which nitrogen and
the earthly constituents are also pres
ent. The food materials which reach
the tree through the roots and leaves
are first digested in the leaves some
what as food is digested in the human
body. and are then sent to all living
parts of the roots, stem, and crown,
where they pass through another pro-
cess Of digestion, and are then either
used at once in growth or stored away
until the proper moment arrives. This
is the general rule, but it is believed
that in some cases food taken up by the
roots can be used without first being
digested in the leaves.
HOW THE TREE BREATHFS.
Besides giving out oxygen IN assimi-
lation. trees also take in oxygen from
the air through their leaves, and
through the minute openings in the
bark called lenticels, such as the oblong
raised spots on the young branches Of
birch and cherry and many other trees.
All plants, like all animals, breathe; and
plants, like animals, breathe in oxygen
and breathe out carbonic acid gas
This process of respiration, or breath
ing of the tree, goes on 10th day and
night. but it is far less active than
assimilation. which takes place only in
;he light Consequently more carbonic
acid gas is taken into the tree than is
given out, and the surplus carbon re-
mains TO be used in growing.
The leaves give out not only the oxy-
gen derived from the decomposition of
carbonic acid gas produced in breath
ing, but also great quantities of water