Ill 



DISTEIBUTIOIT OF AMEEICAN 

 FOEESTS 



THE geographical distribution of 

 trees has been referred to occa- 

 sionally in the preceding chapters. 

 This distribution, gradually accom- 

 plished during the progress of ages, 

 has not been accidental; on the con- 

 trary, it has been due to natural causes, 

 and arises out of the special needs and 

 adaptations of each species. The geol- 

 ogy of a region, which determines in 

 many respects the character of the phy- 

 sical forces of both the earth and the air, 

 is no small factor in the development 

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