98 PRACTICAL FORESTRY IN 



trouble later. The exponents of fall burning also argue that 

 with care they can be ready to fire a very dry slashing safely 

 at the beginning of a rainstorm. Spring burning seems to 

 have the most advocates, but it is doubtful whether any rule 

 for all localities and conditions can be given with confidence. 

 Frequently failure at one season leads to postponement until 

 the next. 



In either case the slashing can be given the advantage of 

 the greatest dryness with safety if it is surrounded by a 

 cleared fire line from which to work. Firing should be 

 against the wind and if the wind changes suddenly the oppo- 

 site edge should be back fired. Previous cutting of all dead 

 trees and snags over 25 feet high is urgently recommended. 

 The camp crew should be held in readiness, well provided 

 with tools ? as insurance against accidental escape. 



Its probable restriction of insect breeding is a point of 

 slash burning likely to receive much future study. It is well 

 known that most forest-injuring insects prefer dying trees 

 to vigorous ones; also that the existence of an abnormal 

 amount of such material tends to abnormal breeding and con- 

 sequent serious attack of vigorous timber when the dead 

 material becomes too dry to be inviting. It is by no means 

 impossible that the supposed immunity of Douglas fir from 

 insect injury may be largely due to the almost universal de- 

 struction by fire of logging debris which would otherwise 

 afford ideal breeding places. 



Fire Lines 



The division of mature forest into compartments separated 

 by fire lines is seldom practicable in this country. Neverthe- 

 less slashings, deadenings and similar fire traps can very often 

 be profitably confined by the cleaning of strips which will not 

 only stop or retard the progress of a moderate fire but also 

 facilitate patrol, fire fighting or back firing. On favorable 

 ground, where some choice is offered, much may be done by 

 falling timber inward so as to leave few tops near the uncut 



