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 blue jays 

 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- 

 lings may establish 

 themselves in the shade 

 of full-grown trees. 



The expense of plant- 

 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. 



FIG. 96. Part of a windbreak of cottonwood, 

 ten years old 



Trees planted 5 ft. x 6ft., thinned to 6ft. x 10ft. 

 The trunks will make good lumber, as the lower 

 branches will all be killed by the shade. Photo- 

 graph by United States Forest Service 



