238 THE PRINCIPLES OF HANDLING WOODLANDS 



( 129.2 F.). 1 Very often the forester wishes to deter- 

 mine, after a fire, the extent of the injury. If the inner 

 bark is brown or black, in contrast to the normal green 

 color, this is an indication that the cambium is dead. 



Injury to Trees. Many surface fires do not kill trees 

 outright, but seriously injure them by killing a portion 

 of the roots or trunks. It is very common to find, after 

 a fire, that nearly all the trees in the forest have been 

 killed on one side. This is usually the leeward side, 

 because here the flames have an opportunity to run in 

 immediate contact with the tree long enough to injure it. 

 If a fire is burning up a slope, even when there is no 

 wind, the upper side of a tree is usually more damaged 

 than the lower side, both because of the accumulation 

 of leaves and other litter above the tree, and because fires 

 are carried upward by the currents of hot air, just as a 

 fire on level ground is swept along by the wind. 



In the case of a well-established tree, the killing of 

 one side may not result in its death for a long period; 

 and if the wound is not large it may heal over. Very 

 commonly, however, the killing of one side of the tree 

 induces the attack of some fungous disease, which ulti- 

 mately results in the tree's death. Trees injured and 

 weakened by fire are subject to the attack of insects. 

 In many cases the death of trees after a burn is the result 

 of insects' work and not of the killing of the tissues by 

 the fire. Damage by fire often follows damage by in- 



1 " Der Waldbau," by Heinrich Mayr, p. 12. 



