396 THE RELATION OF FORESTS AND FOREST FIRES 



FIRE GLADES SURROUNDED BY FIRE-SCARRED TIMBER ON HIGHER GROUND — BLACK HILLS, 



SOUTH DAKOTA 



in this direction, and in addition the behavior of the border forest 

 lands along the eastern edge of the prairies powerfully confirms 

 this view. Where such forest lands have been protected from 

 fire, as they have very largely through the progress of settlement, 

 young trees have usually sprung up in great numbers under or 

 between the scattered veterans which had survived the fires, and 

 a dense and vigorous young growth stands ready to replace by 

 a heavy forest the open park-like condition which the fire had 

 created and maintained. The well-known " oak openings " fur- 

 nish an excellent case in point. In a similar way and for sim- 

 ilar reasons trees are spreading from the borders of streams in the 

 prairies to the grass lands near by. Such indications as these, 

 joined to the occasional discovery of evidences of former tree 

 growth out on the prairie, where trees no longer grow, go far to 

 prove that trees once grew and may grow again much beyond 

 the limits they occupied when tbe white men first entered the 

 country. That fire was a restraining cause admits of no doubt 

 whatever, and that it was the principal cause over vast areas is 



