FOREST PROTECTION 69 



Spruce occupying situations that are more moist than in the 

 case of Scots Pine woods, the latter species suffers more 

 seriously. 



According to the nature of the forest fire, the following 

 distinctions are made : 



Surface or ground fires the commonest form, a burning of 

 the litter or soil-covering of leaves, twigs, grass, etc. 



Crown fires so frequent and disastrous in North America. 

 These burn the crowns, I.e. foliage and branches ; they nearly 

 always originate in a surface fire. 



Stem fires of little importance, taking place usually in 

 single trees when hollow. 



'Deep soil-fires of comparatively rare occurrence. Peaty 

 moorland may become ignited in this way, and burn slowly 

 but persistently. Practically the only measure to adopt 

 against it is to isolate the part on fire by cutting trenches 

 down to the mineral soil. 



Preventive measures should aim at diminishing the risk, 

 and limiting the possible extent of forest fires. 



A system of fire lines, that is, intersecting paths or rides, 

 commonly from eighteen to thirty-six feet wide, should be 

 arranged through the forest, so that though one division may 

 have to be sacrificed, the whole may not be lost. They form 

 the best means of restricting the area of the outbreak, and 

 provide points of attack against it. Marginal belts of rela- 

 tively non-inflammable, broad-leaved species as Birch, Oak, 

 and Poplar ought to be planted where Pine woods border 

 upon roads and railway lines. Restrictions as to lighting fires 

 within the forest and the smoking of tobacco can be drawn 

 up coming into effect during the dangerous seasons of the 

 year. Locomotives running through forests should be fitted 

 with means to prevent the emission of glowing cinders and 

 sparks, and the place and manner of supplying the engine 

 furnaces with fuel can be regulated. 



A ground fire should be attacked from both sides simul- 

 taneously by beating, or rather sweeping, the edge of the 

 burning surface with green branches, so that it becomes 



