Bui. 86, Forest Service, U. S. Dept. of Agriculture. 



PLATE XVII. 



FIG. 1.-A FEW Rows OF COTTONWOOD, WHEN YOUNG, MAKE A FAIRLY DENSE PRO- 

 TECTING BELT. 



FIG. 2. WHEN MATURE, COTTONWOOD MUST BE UNDERPLANTED IF THE BELT is TO 

 RETAIN ITS EFFICIENCY. 



