OUR FORESTS 7 
prepare their seeds for fall sowing. The members of the red-oak 
group and many of the cone-bearing trees take 2 years to mature 
their seed crops. 
The seeds of many trees are winged and are easily scattered by the 
wind. The maples, and the American elm, are among those that be- 
long in this class. The lighter seeds, like those of the elm, may be 
borne long distances. The seeds of the maples, however, are com- 
paratively heavy for fliers and consequently do not get very far 
from the parent tree. Heavier seeds, such as the nuts and acorns, 
may be carried away from the parent tree by birds and small animals 
which feed upon them. 
Most trees provide great quantities of seed, but when the seeds 
have fallen from the tree their fate becomes a matter of chance, and 
out of thousands perhaps only one will take root where it can grow 
to be a tree and in its turn bear seed (fig. 3). 
F—1467 
Ficure 4.—Young and old members of tree families. 
Young trees are growing up under the protection of their parents. 
RELATIONSHIP OF TREES 
Forest trees are in many ways dependent upon their neighbors. 
They increase the fertility of the soil in which they grow; and their 
combined shade keeps the soil about their roots cooler in summer 
than it would be if each tree stood alone. Their interlacing crowns 
form a canopy under which the seedlings of all members of the 
forest community are sheltered in early youth (fig. 4). 
At the same time there goes on in the forest a vigorous struggle 
for the prime necessities of tree life—water, sunlight, and space in 
which to grow. Battling to get ahead of each other, the large trees 
push up towards the light, without which their leaves cannot digest 
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