400 



How Liv'nig Things Affect One Another unit vn 



Fig. 348 Every year in our country forest fires destroy an average of twelve nnllioii 

 acres of trees. ]Vbat are the other costs of forest fires besides the loss of trees that 

 might have been used for Iwnber and paper pzdp? What can be done to prevent such 

 great losses? (u. s. forest service) 



Cut but 

 restocked 



Fig. 349 As leaves and small branches fall, 

 collect, and decay, a spongy layer of humus 

 develops on the forest floor. How does this pre- 

 vent the runoff of water? (okerberg - Chicago 



APPARATUS company) 



Practically barren 

 after cutting 



Uncut 



Fig. 350 When the first white settlers came to 

 this cofitinent, there were more than Soo,ooo,- 

 000 acres of untouched forest. How many 

 acres have beefi cut? Why were the trees cut? 

 How many acres are left? How ninch is be- 

 ing replanted? 



