254 



FOREST PROTECTION 



and Oregon. Climate and forest conditions are responsible 

 for this grouping. Throughout the southern half of the coun- 

 try, fires, while prevalent, are of a less severe character. 



To bring out the location and extent of large fires in the 

 past a map prepared by the United States Forest Service,^ 

 showing historic fires, is reproduced. (See Fig 82.) 



Fig. 82. 



Map showing the location of the principal historic forest fires which have 

 occurred in the United States since the year 1800. Copied from "Forest 

 Fires," by F. G. Plummer, Bulletin 117, Forest Service, United States De- 

 partment of Agriculture, page 22. 



Factors Influencing the Spread and Severity of Forest 

 Fires. — All silvicultural operations should so far as practi- 

 cable be conducted in a manner that will minimize the creation 

 of conditions favorable for the spread of forest fires. Unfortu- 

 nately most of the factors influencing the spread and severity 



