Eifect of Forest Fires on Trees. 205 



V. EFFECT OF FOREST FIRES ON REPRODUCTION. 



One of the worst things about fires is that they generally kill 

 more than one tree generation. After a severe fire has killed 

 everything, all reproduction must come from seed produced off 

 the burned area. If this is very large it may take several tree 

 generations to completely restock it. It is doubtful if this form 

 of reforestation has ever been necessary in southern New Eng- 

 land. 



Effect of Seedmg: For light surface fires the amount 

 of injury varies with the season of the fire. One in spring kills 

 all seedlings from seed of the previous fall as well as all un- 

 germinated seed. Fires at the close of a good seed year for a 

 species may prevent its reproduction till the next seed year. In 

 Connecticut, the fall of 1910 produced a large crop of Red Oak 

 acorns. The spring of 191 1 was very dry and fires were frequent. 

 On the many tracks burned there are no seedlings from this crop. 



Fall fires coming before the seed falls, but after it is ripe, may 

 have no effect on seeding; may help it, hinder it, or prevent it 

 altogether, all depending upon how the fire leaves the forest floor. 



Although no studies have been made on this point it is likely 

 that continued fires, by causing deterioration of the site, affect 

 seed production and fertility adversely, even though, as has been 

 recently claimed for Western Yellow Pine, fire scars stimulate 

 seed production.* 



Resistance of Seedlings: It is doubtful if an oak seedling 

 can survive a fire of the lightest kind unless it be at least 

 three years old. Certainly other species are not more resistant. 

 Above that size, till they reach a diameter of three inches, they are 

 killed back by most fires, although two inch specimens sometimes 

 survive light fall fires. Severe fires burning up hill may in spring 

 kill oaks up to six, and chestnuts up to ten inches in diameter. A 

 six-inch oak averages from fifteen to twenty-five years old. 



There is then a period from germination to the age of three 

 years during which oak seedlings are sure to be killed back ; a 

 period from three to ten years, liable to be killed back ; one from 

 ten to fifteen years when saplings run a good chance of being 

 killed back; and a final period from fifteen to twenty-five years 

 during which poles stand a possibility of being killed back. 



Seedling Sprouts: Seedlings killed back often sprout again. 



*Circular 196, U. S. F. S. "Influence of Age and Condition of the Tree 

 on Seed Production in Western Yellow Pine." 



