THE PROTECTION OF SEEDING AND PLANTING SITES 185 



plete is the protection afforded. Fire lines should not be con- 

 structed, however, with the idea that fires will be stopped by 

 them under all conditions. Even narrow lines as afforded by 

 trails or roads will stop most surface fires. The width of the line 



FIG. 31. A broad fire line adjacent to a public highway, protecting 

 a white pine plantation. 



necessary to stop a fire depends very largely upon the movement 

 of the wind. It is not practical to construct a break wide enough 

 to secure absolute safety when the wind reaches the velocity of 

 30 or more miles an hour. It is imperative that fire lines be prop- 

 erly maintained. If permitted to become covered with grass and 

 other vegetation in dried condition, they are worse than none at 

 all. A fire line should usually receive attention at least twice a 

 year, viz., just before the autumn fire season and in early spring. 

 Where stumps, rocks, and other obstructions are absent, plowing 

 is an effective method of keeping the area free from vegetation and 

 the resulting inflammable material. When large, continuous tracts 

 are seeded or planted it is often desirable to subdivide the area 

 into from 20- to 40-acre divisions separated from each other by 

 suitable fire lines. 



