TIMBER; FORESTRY — 115 
109. Propagation of trees in woodlands. Many kinds of 
forest can be so managed that the young trees sown by natural 
agencies suffice to keep up the stand when the largest trees are 
felled (fig. 97). The 
seeds of most conifers 
are readily carried con- 
siderable distances by 
the wind, and those of 
many broad-leaved trees, 
as birches, elms, ashes, 
maples, and others, are 
carried in the same 
way. Squirrels carry 
many nuts and acorns 
and often bury them 
where they can grow. 
Many birds — for ex- 
ample, the bluejays — 
carry acorns, and most 
fruit-eating birds dis- 
seminate such seeds as 
those of the red cedars, 
wild cherries, hack- 
berry, mulberry, and 
a few other trees, often 
carrying them many 
miles. Tolerant seed- Fic. 96. Part of a windbreak of cottonwood, 
lings may establish ten years old 
themselvesinthe shade Trees planted 5 ft. x 6 ft., thinned to 6 ft. x 10 ft. 
. The trunks will make good lumber, as the lower 
of full-gr own trees. branches will all be killed by the shade. Photo- 
The expense of plant- graph by United States Forest Service 
ing seeds or setting out 
young trees in woodlands is usually so great as to make it 
unprofitable, since the natural growth will renew itself with 
a little artificial aid. It is, however, important to clear away 
undershrubs that are overshadowing desirable seedling trees. 
