42 FORESTRY 



be nothing if the fires continue to burn. Upon such soils, 

 a considerable quantity of grass and weeds springs up, 

 which forms food for such periodic fires. 



Hardwood seedlings are just as sensitive, on the whole, 

 as conifers but they possess, almost from the start, the ca- 

 pacity for sprouting, so will come up after a fire. The 

 older a tree gets, the more severe must a fire be to kill it, 

 so that in regions of frequent surface fires, the mature tim- 

 ber stands from year to year apparently uninjured. This 

 apparent freedom from injury may in some cases be actual. 

 The bark is so thick and the fires so light that the tree 

 continues sound. Even in such a case, all the natural cov- 

 ering which preserves the moisture of the forest floor is 

 burned up and it is probable that growth is interfered with 

 by the excessive exposure of the soil. But once let the bark 

 be burned through anywhere and the succeeding fires 

 each eat out a little larger hole until the tree may burn 

 completely off. Some pines, as the Norway pine of the 

 Lake States, and the Longleaf pine, show this capacity 

 for fire resistance in the face of repeated small fires. With 

 many trees, both pines and hardwoods, the fire may kill 

 the cambium on only one side. This is usually the side 

 opposite to the direction from which the fire is coming. 

 The fire forms an eddy and licks the face of the tree — 

 burning a strip of bark sometimes 6 to 10 feet high. If 

 young, a tree may heal such a wound completely, so that 

 it cannot be noticed until the tree is felled, when the old 

 scar will be seen, with the annual layers of wood formed 

 since the fire each closing in across the gap until it is finally 

 bridged. The younger the tree, if not killed outright, the 

 greater is its chance of recovery, provided a second fire 

 does not keep the wound open. But this is not the end 

 of the damage. The spores of fungi often find lodgement 

 in such fire-scars, and develop rot in the heart of the tree, 

 so that the damage done from this source may in a few 

 years exceed that caused by the fire itself. 



