Tolerance of Red Gum

Throughout its entire life red gum is intolerant in shade, there are
practically no red seedlings under the dense forest cover of the
bottom land, and while a good many may come up under the pine forest
on the drier uplands, they seldom develop into large trees. As a rule
seedlings appear only in clearings or in open spots in the forest. It
is seldom that an over-topped tree is found, for the gum dies quickly
if suppressed, and is consequently nearly always a dominant or
intermediate tree. In a hardwood bottom forest the timber trees are
all of nearly the same age over considerable areas, and there is
little young growth to be found in the older stands. The reason for
this is the intolerance of most of the swamp species. A scale of
intolerance containing the important species, and beginning with the
most light-demanding, would run as follows: Cottonwood, sycamore, red
gum, white elm, white ash, and red maple.

Demands upon Soil and Moisture

While the red gum grows in various situations, it prefers the deep,
rich soil of the hardwood bottoms, and there reaches its best
development (see Fig. 10). It requires considerable soil moisture,
though it does not grow in the wetter swamps, and does not thrive on
dry pine land. Seedlings, however, are often found in large numbers on
the edges of the uplands and even on the sandy pine land, but they
seldom live beyond the pole stage. When they do, they form small,
scrubby trees that are of little value. Where the soil is dry the tree
has a long tap root. In the swamps, where the roots can obtain water
easily, the development of the tap root is poor, and it is only
moderate on the glade bottom lands, where there is considerable
moisture throughout the year, but no standing water in the summer
months.

Reproduction of Red Gum

[Illustration: Fig. 12. Second Growth Red Gum, Ash,
Cottonwood, and Sycamore.]

Red gum reproduces both by seed and by sprouts (see Fig. 12). It
produces seed fairly abundantly every year, but about once in three
years there is an extremely heavy production. The tree begins to bear
seed when twenty-five to thirty years old, and seeds vigorously up to
an age of one hundred and fifty years, when its productive power
begins to diminish. A great part of the seed, however, is abortive.
Red gum is not fastidious in regard to its germinating bed; it comes
up readily on sod in