PROTF.CTIOX Ol l-ORI.STS FROM KIRF, 235 



ley fire in Minnesota in I S94, are swept along at a much 

 greater rate, particularl\- if the starting of new fires b)' 

 burning cinders is taken into consideration. Kven in 

 extreme cases, ho\ve\'er, it is cjuestionable \\hether crown 

 fires burn at a rate of more than from 6 to 10 miles an 

 hour. 



The behavior of a crown iire depends on the character 

 of the crowns. Crown fires are mainh' confined to coni- 

 ferous forests, for the leaves of hardwoods are not easily 

 Ignited. 



They may, however, run through forests of mixed 

 hardwoods and conifers, and in SLich cases the heat gen- 

 erated IS SO great that the hardwood lea\'es are scorched 

 or killed. The velocit\' of the fire depends, further, on 

 the density of the stand, the thickness of the crowns, and 

 the force and steadiness of the wind. Other influences 

 affect the severit\' of crown hres in much the same way as 

 the\' affect that of surface fires. 



Damage by Fires 



The damage done by forest fires may be discussed 

 under the following heads: 



1 . Death of standing trees. 



2. Injurx' to trees that are not killed. 



3. Injurx' to the soil. 



4. l^eduction of the rate of growth of the stand. 



5. Effect on reproduction. 



Death of Standing Trees. — Crown fires usually kill 

 outright all trees in their path. In a severe crown fire 



