SILVICULTURE. 193 



which lead to such results will be discussed in a 

 succeeding chapter. 



Here the preventive silvicultural measures and 

 arrangements in the forest, which are designed to 

 reduce the fire danger, are to be only briefly 

 enumerated. 



The experience that deciduous-leaved woods are 

 less liable to danger suggests the maintenance of 

 mixed forest ; the fact that old timber is compara- 

 tively safer, and that on large wind-swept areas the 

 heat and the rapidity of progress of a fire is in- 

 creased, leads to distributing the felling areas, and 

 that means the areas of young crop, isolating them, 

 making them smaller, and having them surrounded 

 by older timber. Removal of the dead and dying 

 trees by systematic thinnings wherever possible, 

 and the disposal of the slash from logging opera- 

 tions, are obvious means of reducing the danger. 



In German forest districts, more especially those 

 unduly exposed to fire danger, a subdivision of the 

 forest into blocks surrounded by avenues, or so- 

 called rides, of 8 to 40 rods width, is made. 

 These rides, kept free from inflammable material 

 by annual burning, or perhaps by sowing to grass, 

 serve the purpose of confining the fire within the 

 block, and furnishing a base from which to fight 

 a fire, for which the frequent roads may also be 

 utilized. 



But these openings are worse than useless unless 

 kept in proper condition, and unless the forces to 



