WORK OF THE UNITED STATES FOREST SERVICE 25 
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FicurE 17.—Cottonwood planting crew in action in South Dakota; 1-year seedlings are 
being planted 4 feet apart in rows 8 feet apart. 
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FIGurRE 18.—When planted on an Oklahoma farm March 5, 1956, these cottonwoods were 
| 1-year seedlings. The photo was taken November 10, 1936. The trees are growing 
into an effective shelterbelt designed to keep sand from a river bed from being deposited 
on a valuable field. 
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| ® Shelterbelts provide protection from winds in a region where nat- 
9 ural means of protection are largely lacking. They serve also as 
| snow traps and furnish shade. The trees help to prevent the quick 
. drying and subsequent “blowing” of soils by checking the velocity 
of the winds. Similarly they protect growing crops from critical 
