METHODS OF SLASH DISPOS.\L 227 



above the ground and being able, when burning, to carry 

 flames into the crowns of trees, constitute a more serious fire 

 menace to standing trees than do lopped tops.^ 



The method does not remove any of the slash from the 

 felling area, it simply changes the position of a portion, usu- 

 ally a small proportion of the material. 



Light Burning. — Light burning is not a method of slash 

 disposal. It consists in the annual or periodic burning over 

 broadcast of forest areas before instead of after cutting opera- 

 tions. Slash as previously defined is created mainly as a 

 result of such operations. 



Light burning is an intentional use of surface fires to keep 

 the ground free of the highly inflammable material which is 

 made up of Htter, ground cover, underbrush and reproduction. 



The theory is that if such material is burned at relatively 

 frequent intervals a fire, hot enough to injure the less inflam- 

 mable but more valuable material, namely the standing tim- 

 ber, cannot start. This would be logic did it not overlook 

 the injury to the productive power of the forest caused by 

 light burning. It may be summarized under the following 

 headings: 



{a) Injury to the Soil. — Light burning proposes to prevent 

 the accumulation of fitter which is essential for the produc- 

 tion of humus, this in turn being of vital importance in main- 

 taining the physical properties of the soil in best condition. 

 Annual burning removes the fitter as fast as it forms and has 

 a serious effect on the humus content. Periodic burning at 

 intervals of three to five years is nearly as bad, since it re- 

 quires several years for fitter, after its fall, to decompose into 

 humus. Sandy soils with level topography are least injured, 

 while heavy soils of fine texture and on slopes which may 

 erode suffer the greatest injury. 



{h) Injury to Reproduction. — A fire hot enough to consume 



