Atlanta semi-weekly journal. (Atlanta, Ga.) 1898-1920, 1919-03-11
AGRICULTURAL EDUCATION
BY DR. ANDREW NJ SOULE
Some Suggestions About Shade
Trees

frees
PLANT a shade tree and leave some
thing to add to the pleasure of pos
terity" is a worthy adage. To those
who live in humid climates shade
trees have become so common thtt
| their beauty is often overlooked or
forgotten altogether. There is moth.
ing so attractive or edifying than a
beautiful, shapely tree. There is
nothing easier to have in this great
southeastern section of the United
States Few sections of the country
possess more beautiful or desirable
types of shade trees, and the rate
at which they grow is matter of
surprise to many visitors from less
favored sections. The enhancement
Identification of the country may be
effected so easily through the plant
ing of trees that the emphasis of this
subject now seems timely and de-
Sirable. Therefore some excerpts
from a discussion of the shade tree
proposition prepared by the fores-
try division of the Georgia State
College of Agriculture are both time
ly and suggestive, and represent a
theme the editor desires to direct
to the attention of the readers of
the agricultural columns at this
time.
Tree Is Alive
The tree is a living thing. Only
in the lack of mortality and senSl-
tiveness and in it's ability to manu-
facture food material from simple
inorganic substances does the tree
differ from the animal. Trees work,
consume food, breathe, perspire, re-
produce and associate together IN
communities and villages. Grown IN
the open the tree takes very dill
ferent form from that which it would
assume in the forest, where the sew
eral individuals compete with eacn
other for light and moisture. only
part of 1.-The struggle for existence
occurs above ground; the more dead
ly competition takes place in the
ground where the many roots nght
for the available water. In thinking
of the tree one should not picture
the stem and branches alone, but WIS.,
ualize the enormous root-SyStem pc
low the ground-a system more eX-
tensive usually than the entire crown
Or branches, twigs and leaves. When
trees are crowded the struggle is be-
low ground although the evidence oc-
ours above in the following leaves
and dying branches.
AS stated above, trees differ from
animals chiefly in that they are
CAPABLE of manufacturing their tooo
from simple, inorganic substances,
the bulk of which comes from tho air.
This is readily understood when WOOD
is burned. The elements taken from
the air are returned in the form Oh
gas and smoke; the elements taken
from the soil remains as ashes. ASH
constitutes not more than one or two
per cent of the weight of WOOD. The
soil moisture, with certain elements
in solution potash, phosphorus, M
trogen, iron, sulphur, lime, etc.), is
absorbed by the numerous FOCUS,
forced up the stem through tlny
tubes in the wood, and furnished to
the leaves, where the manufacture
of food takes place.
Only the green material (cnoroc
phyID in the leaf has the power OF
presence of sunlight. The carbon
dioxide from the air is taken into
the leaf through tiny holes (stoma-
tai, where it comes within reach OF
the chorophyll. The carbon diox1dc
is broken down into simple elements;
the oxygen is thrown off and the
carbon retained. The elements from
the sap (soil moisture) are united
with the carbon (from the carbon
dioxide), and the hydrogen and oXy-
gen (from the water), to form sugar.
the food material of the plant.
The sugar may be used as such or
may be stored as starch for future
use. When used, it forms cellulOse
and lignin (wOod).
the tree is to develop normally ana
remain healthy. Light and soil mo1s-
ture are the chief factors Of tree
growth. Of course it must be under
stood that temperature is an 1mpor-
tant consideration-that as a rule
it is not safe to transplant tree
from the tropics to the temperate
regions, or vice versa. When deal
ing with native species, temperature
as a factor of growth need not ne
considered.
All trees do not have the same
light requirements-cer kinds
have adapted themselves to partial
shade Those which strive best in
full sunlight are known as light de-
manders;" those which are adapted
to shade as shade endurerS.' Many
trees will endure partial shade when
young but demand full light when
termediate." The following table
gives some idea of the relative light
requirements of our common trees
Light Demanders-Yellow poplar,
white elm, water oak, hickory, long
leaf pine, shortleaf pine, cypress.
Intermediate-Che red oak,
sycamore, black. walnut, white pine.
loblolly pine, ash.
Shade Endurers-Dogwood, maple,
beech Eastwood, black gum, hem
Light requirements should be con-
sidered when selecting the proper
tree for planting. One of the light
demanders" will prove more salts
factory for planting in the open. On
the other hand, a shade endurer"
will give better results when plant
ed in the partial shade of other
trees or on the north side of build