Chapter VII. 



THE EXHAUSTION" OF THE FOEEST. 



The exhaustion of the forest in the United States is due to two 

 main causes: (1) Fire, and (2) Destructive Lumbering. 



FIKE. 



It is not commonly realized that forest fires are almost entirely 

 the result of human agency. When cruisers first began to locate 

 claims in this country, practically no regions had been devastated by 

 fire. Now such regions are to be seen everywhere. Altho lightning 



Fig. 104. Slash, Left in Uie Woods, and'iReady to Catcli Fire. 

 U. S. Forest .Service. 



occasionally sets fire to forests, especially in the Rocky Mountains, 

 the losses from this cause are trifling compared with the total loss. 



Opportuni.'ies for fire. There are a number of facts that make the 

 forest peculiarly liable to fire. Especially in the fall there are great 

 quantities of inflammable materia], such as dry leaves, twigs, and duff 

 lying loose ready for ignition. The bark of some trees, as "paper 

 birch," and the leaves of others, as conifers, are very inflammable. It 

 follows that fires are more common in coniferous than in deciduous 

 forests. After lumbering or windfalls, the accumulated "slash" burns 

 easily and furiously. Fig. 104. Moreover a region once burned over, 



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