290 LIVING THINGS IN THEIR ENVIRONMENT 



The diagram on the left shows the life zones on a mountain rising from the desert 

 in Arizona. See if you can find any of these zones in the picture at the right. 



at 6000 feet elevation; while at 11,000 feet you could 

 have a snow fight. This change in vegetation is caused 

 largely by differences in temperature. 



On a mountain side in the eastern United States the 

 forests are much denser and clothe the mountains from 

 base to peak. Only at an altitude of over 5000 feet do 

 the trees begin to get smaller. At the summit of Mt. 

 Washington in the White Mountains or Mt. Marcy in 

 the Adirondacks we do find alpine conditions with bare 

 rocks and a few stunted trees in sheltered places. 



Forests Differ in Different Places. The forests of the 

 western mountains are largely yellow pines, with scattered 

 conifers and a few aspens or other deciduous trees. In 

 the East, however, we have largely mixed forests : hem- 

 locks, spruces intermingled with ash, beech, hickory, 

 birch, maple, walnut, and many other hardwoods. In 

 the southern states the conifers are mostly cypress and 

 pine, while catalpa, magnolia, locusts, and sweet gums are 

 added to the list of forest trees given above. Some 

 forests in the areas where rain is abundant are carpeted 

 with fern and other undergrowth, while in the dryer West 

 the trees are not crowded so closely together and forests 



