SOME PHASES IN THE FORMATION OF FIRE SCARS 

 By H. G. Lachmund 



Forest fires in the coniferous forests in California have in the past 

 been typical ground fires. As a result of their constant recurrence 

 open fire scars are abundant. Commonly these scars, when examined 

 closely, will be found to have been hollowed out by successive fires. 

 In the course of time a number of these lesions heal over and become 

 enclosed. In addition, another type of injury representing the first 

 stages in the process of fire scar formation is common on areas 

 recently swept by fire. Where fire at the base of a tree is sustained 

 long enough by accumulated litter or resin exudations the heat becomes 

 sufficiently intense to kill living tissues without actually burning away 

 the bark, which at first remains closely attached to the sapwood. But 

 in the healing process calluses form beneath the bark around the 

 edges of the killed area and, gradually growing in from all sides, force 

 the old bark away from the dead sapwood. The bulging growth of the 

 calluses and drying out cause the bark to crack and split, following 

 which it commences to drop away in pieces until finally the sapwood 

 is exposed. 



The period of time required until the wood becomes exposed varies 

 according to the rate of growth of the tree, the form of the calluses, 

 and the size of the wound. Even in fast-growing trees observations 

 have shown that five to ten years may elapse before the old bark 

 covering the wound peels off, while in slow-growing trees it may take 

 a considerably longer time. Due to their inconspicuous character 

 during the years immediately following the fire these wounds are 

 generally overlooked though they may constitute a considerable pro- 

 portion of the fire damage to the stand. 



As a direct cause of loss in merchantable volume they are negligible, 

 but in providing a mode of entrance to infection they may be of con- 

 siderable importance. As long as the old bark adheres to the injured 

 portion it affords more or less protection. When it drops off and 

 leaves an open wound destructive fungi find an easy access to the 

 wood. For this reason care should be taken, in accurate appraisal of 

 fire damage to stands recently swept by ground fires, to search for 

 these fire injuries, particularly if the stand is largely composed of 

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