INJURY CAUSED BY FOREST FIRES 245 



fire than the young trees because with age the bark thickens 

 and tends to become more corky. Trees which secrete resin in 

 the bark or exude pitch as a result of insect attacks are easily 

 injured. Where the pitch is plentiful a fire may run up the 

 tree killing the cambium on one side for many feet above the 

 ground and leaving a long scar called a cat's face. 



Conifers suffer more severely from fire than hardwoods. 



When heat from a fire reaches the roots of trees severe 

 injury or death results. This is the case because tree roots are 

 less thoroughly protected by thick bark than the portions above 

 ground, and probably are more sensitive to heat. Trees with 

 shallow root systems suffer more than the deep-rooted species. 



Old trees can be found all hollowed out at the base by fires. 

 In some cases spaces big enough to admit one or more men 

 have been burned out. Such hollows are rarely if ever the 

 work of one fire but represent the effects of several fires. 

 Once the bark has been burned away on one side succeeding 

 fires burn more readily in the exposed wood. 



Where trees containing merchantable material are killed 

 outright they should be cut and utilized before the timber 

 decays or is attacked by insects. This is not always possible 

 if the trees are few in number, scattered or located in inac- 

 cessible places. Frequently fire killed timber can be sal- 

 vaged for a large percentage of its value before the fire. 

 Burned timber in some cases is valueless a year after the fire, 

 in other cases remains sound for several years. Climatic 

 conditions, the species, and the question of whether the bark 

 falls from the trunk soon after the fire are the main factors 

 influencing the length of time during which fire killed timber 

 remains sound. 



In a dry climate with a species relatively free from insects 

 and fungi and under circumstances causing the tree to shed 

 its bark deterioration is delayed. 



