Effect of Forest Fires on Trees. 199 



parasitica, the Chestnut Bark Fungus, seems to be more numerous 

 and severe on fire injured trees. 



Perhaps the worst effect of fungi is the decay of heartwood. 

 A fire scar may completely heal over, yet if decay has started it is 

 likely to continue till the entire interior of the tree is riddled. 



Woods resist decay to varying degrees. White Oak and Chest- 

 nut probably have the most decay resistant wood of any southern 

 New England hardwood; aspen, the most perishable, fire injured 

 specimens seldom lasting more than a decade or two, while White 

 Oak will resist decay even though badly injured at the base for 

 several times that long. The subsequent resistance of the aspen 

 is low ; of the oak high. 



Next to fungi insects play the largest part in the after effects of 

 fire. Weak or injured trees are generally more subject to insect 

 attacks than sound ones. The exposing of the wood by the burn- 

 ing of the bark is not a consideration since insects enter in other 

 ways. Like fungi they cause damage in two ways: (i) By at- 

 tacking the living portions of the tree, reducing its vitality, per- 

 haps killing it, (2) By boring in the wood, reducing its strength, 

 thus inducing wind break and lowering its value. Insect channels 

 in timber facilitate the entrance of certain fungi. 



Under the first class of injuries come those by bark beetles. 

 These mostly belong to the Family Scolytidae. The Hickory 

 Bark Beetle (Scolytus quadrispinosus) is active in destroying the 

 life of fire injured hickories and it is rarely that they escape its 

 attacks. 



Concerning wood boring insects Hopkins says, "The principal 

 damages to dying and dead hardwood trees is caused by certain 

 round-headed borers, — by timber worms, — and by Ambrosia 

 beetles. All hardwoods suffer more or less, but the greatest 

 damage is done to the wood of hickory, ash, oak, and chestnut, 

 which is often reduced in value ten to fifteen per cent, or more 

 during a period in which it would otherwise remain sound and 

 available for commercial purposes." Elsewhere he mentions fire 

 as an agent inducing insect attacks. 



It is not uncommon for insect and fungus attack to both follow 

 in the wake of a fire which has opened the way for the entrance 

 of the fungus and weakened the tree for insect resistance. 



Windbreak is another after effect of fire. Scarred trees are 



