104 GEOLOGICAL SURVEY OF NEW JERSEY. 



spring before the sap begins to move, the damage is much less 

 than after the season of vegetaion has begun. Decay frequently 

 creeps in at the butt of severely burned timber. 



EFFECT ON CEDAR SWAMPS. 



White Cedar is extremely sensitive to fire and is easily killed, 

 especially if the crown is affected. As a rule, however, Cedar 

 swamps will not burn except in the early summer, when it is 

 very dry, and often they will not burn even then. Wet swamps 

 burn only in extraordinarily dry years, or when an unusually 

 hot fire is driven through the trees by a strong wind. The trees 

 on the edges of swamps, however, are frequently killed before 

 the fire is stopped by the damp sphagnum moss. Sometimes 

 the larger trees are not killed outright, but die gradually, 

 beginning in the tops. 



INJURY TO YOUNG GROWTH. 



The larger hardwood trees resist fires admirably, and are killed 

 only in the case of very severe fires. Young growth is often 

 killed outright. All young trees are more sensitive to fire than 

 larger ones, because the bark is thin and delicate, and also 

 because the branches being low what is a surface-fire is to them 

 a crown-fire, killing their tender shoots. Young Pitch Pine, 

 however, withstands remarkably severe burning. Frequently 

 surface-fires burn up to the crowns of small Pitch Pine, scorch- 

 ing the lower branches, but leaving most of the crown intact, 

 and with it the life of the tree. 



INJURY TO THE SOIL. 



One injurious effect of forest fires which is apt to be neglected 

 or even disputed is that which results from the destruction of 

 the layer of vegetable waste and mold which is always found 

 on the ground in undisturbed forests. This forest floor, as it is 

 called, is made up of two parts : ist, the upper wholly or par- 

 tially decayed mass of leaves, twigs, and other vegetable material, 

 called litter ; and ad, the thick, brownish, crumbly mass of real 



