200 Forestry Quarterly. 



often unable to withstand the force of the wind and are over- 

 thrown while still living. A tree may stand for several years 

 after a fire and then be wind thrown. The ease with which this 

 takes place varies with the strength and resistance of the wood. 

 A tree with strong, tough and elastic wood will stand long after 

 one with weak and perishable wood has been blown down. 

 Hickory saplings are often found burned to beyond the center, yet 

 still standing because the wood is tough. Hickories are thin- 

 barked and easily injured by light fires, yet their tough wood 

 makes them rather resistant. Their subsequent is higher than 

 than their initial resistance. 



Gray birch has a rather hard, non-combustible bark. It often 

 escapes fires that scar Chestnut and Red Maple, but its wood is 

 very perishable and quickly rots after the bark has been pierced 

 so that fungus spores may enter ; hence it easily becomes a prey to 

 windbreak, succumbing long before its neighbors which were more 

 seriously injured in the first place. Its initia is higher than its 

 subsequent resistance. 



Swamp fires that have burned down to the roots are often fol- 

 lowed by the overthrow of nearly all the dead trees, which may 

 still be sound, but whose roots have decayed. 



Recovery Power: While this destructive process, a com- 

 bination of fungi, insects, and wind, is at work, the tree is not 

 only passively resisting their attacks, but is striving to heal its 

 injuries by covering them with new growth. 



If a tree is young and vigorous the wound may soon be covered, 

 but the damage is not thereby entirely repaired, since the energy 

 the tree has put forth to repair it, has been subtracted from normal 

 growth. The extent of the checking of growth depends upon the 

 degree of injury. A stump analysis does not always show it, the 

 rings being actually wider, since immediately after a fire the tree 

 has to use most of its energy to heal its basal wound. Higher up 

 the narrowing effect is observed. 



The ability of a species to heal over its wounds has much to do 

 with its holding its place in a burned stand. One which rapidly 

 heals an injury, keeps out decay effectually, strengthens its base 

 sooner, and is less liable to windthrow. White oak is especially 

 active in this respect and soon heals an ordinary scar. It probably 

 has a higher recovery pozvcr than any other species of the region. 



