PROTECTION 161 



thrive unless they fall upon the heartwood of the 

 tree. In this way certain diseases of the heartwood, 

 which result in rot or decay, can very frequently 

 be traced directly to fire scars, lightning scars, spike 



tops/ broken limbs or branches, and other mechan- 



i ' - '** ' 



ical destruction caused by lightning, fire, storms, 



^oudbursts, or heavy snow-fall. 



Ifjre as a cau& of wounds is responsible for 



t 



more cases of heartrot than all other injuries taken 

 together. For this reason the protection of forests 

 from fire is the most important preventive measure 

 that can be taken to eradicate tree diseases. In 

 fact, the best way of controlling diseases is by pre- 

 venting them, and the Forest officers are endeavor- 

 ing to eliminate any danger to the health of the 

 forest, to prevent the injury of the trees, and to 

 establish healthy conditions for their growth. This 

 is forest hygiene, and it bears the same relation to 

 the trees and forests as personal hygiene and com- 

 munity sanitation do to persons and communities. 



It is impossible to grow a sound and thrifty forest 

 for future generations if there are unhealthful con- 

 ditions in the forest that are a constant menace to 

 the trees. The first step in this hygienic work is 

 close observation on the part of the Forest officers. 



