SHELTER-BELT DEMONSTRATIOXS OX THE GREAT PLAIXS. 7 



the region furnishes what is perhaps the most important source of 

 material for shelter-belt planting. 



Figure 2 shows the native growth of western cotton wood, box elder, 

 and green ash in the river bottom, with western yellow pine on the 

 adjoining hills in the Yellowstone Eiver valley at Pompeys Pillar in 

 southern Montana. 



Figure 3 is a view in the Turtle Mountains, Bottineau County, 

 N. Dak., showing the native tree growth, consisting of cottonwood, 

 l)alsam poplar, aspen, white elm, bur oak, and green ash. 



The species that make up this native growth are of two general 

 classes: Those which have progressed up the Mississippi-Missouri 

 ]R.iver system from the east and those which have advanced down the 

 western sources of this same svstem from the Eockv Mountains. 



Fig. 3. — View in the Turtle Mountains, Buttini.'au County. X. Dal;. -Ii living native tree 

 growth consisting of cottonwood, balsam, poplar, aspen, white elm, bur oak, and green 

 ash. 



Beside these native trees a number of species have been introduced 

 from other parts of the United States and Canada and from certain 

 European and Asiatic countries. Some of these introduced species 

 are fully as adaptable to shelter-belt use as any of the native species, 

 while a number of the native trees can not be successfully trans- 

 planted to the open plains. 



The following paragraphs give brief descriptions of practically 

 all of the trees which have been used in shelter-belt planting in the 

 northern Great Plains region. The list is not exhaustive, however, 

 as there are a number of other species that can doubtless be made 

 to grow, but about which little data are available at the present 

 time. 



DECIDUOUS OR HARDWOOD SPECIES NATIVE TO THE REGION. 



Box elder. — The box elder {^Acer negundo) is found in practically 

 all of the river valleys to the foothills of the Rocky Mountains. 



