136 Third Annual Report of the 



bine to make possible an extensive conflagration. The crown fires 

 owe their origin either to surface fires or ground fires. Ground 

 or surface fires may be burning over an area of forest where the 

 topography is varied and do but little damage until they come to 

 the top of a ridge or knoll where the wind can reach them to better 

 advantage, when the increased draft thus afforded them, causes 

 them to run up the tree trunks and communicate fire to the 

 crowns or tops of the trees. Forests of coniferous trees are 

 especially prone to suffer from fires of this kind. The resinous 

 character of the trees affords excellent fuel for fire, and when the 

 fire has reached the crowns, the increased draft which it receives 

 causes it to travel with extreme rapidity. All the disastrous 

 forest fires of history have developed into crown fires before they 

 have done the greater part of their damage. It is difficult to 

 estimate the speed with which a crown fire travels, but there is no 

 doubt that these fires have frequently attained a speed of several 

 miles an hcur. 



DAMAGE DONE BY FIRES 



The casual observer seldom realizes the entire extent of the 

 damage which is done by a forest fire. Everyone will note the 

 trees which have been blackened and killed outright, but few stop 

 to realize the loss of young growth or reproduction, the injury 

 to the soil, and the indirect damage to the larger trees. This 

 brings up the question of the kinds of damage, which may be 

 roughly classified as " Direct " and " Indirect." 



Direct Damage 

 Under the head of direct damage we consider the trees which 

 have been entirely consumed, those which have been killed, but 

 not destroyed, those which have been badly burned around the 

 roots, etc. Crown fires are the only fires which actually consume 

 large trees, but in the case of a severe crown fire, it is no un- 

 usual occurrence to have a large part of both the hard and soft- 

 wood timber on an area completely destroyed. It is often exceed- 

 ingly difficult to tell just which trees have been killed by fire. 

 Some retain a spark of vitality for a year or two after the fire, 

 and then die, as a direct result of being scorched. While it is 



