Table 14. — Fire statistics, Interior versus Southeastern Alaska 



Lightning Man-caused Total 



Interior Southeast Interior Southeast Interior Southeast 



Number Acres Number Acres Number Acres Number Acres Number Acres Number Acres 



1940-49 200 no data 1 0+ 938 no data 292 1,649 1,138 12,411,076 293 1,649 



1950-58 546 7,665,726 3 1 1,734 2,406,442 234 5,738 2,280 10,072,168 237 5,739 



1950-58 Av. 61 851,747 0.3 0+ 193 267,382 26 638 253 1,119,130 26 638 



Source: Southeast: National Forest Fire Reports, USDA, Forest Service. 



Interior: Annual Reports of the Director (Statistical Appendix). 



choose between fires when many start during a 

 short period; and (4) under a general smoke pall 

 some fires burn without being detected. 



Thirty-three percent of all lightning fires are 

 never attacked, while only 9 percent of man- 

 caused fires are not; however, the actual number 

 of no-action fires per year is about the same for 

 both general causes. This 9 percent accounts for 

 68 percent of the area burned by man-caused 

 fires. 



A lightning fire usually is 10 times the size 

 of a man-caused fire; but an average no-action 

 lightning fire is only 1 '/j times the size of a 

 no-action man-caused fire. Many lightning fires 

 are held down in early stages by such elements 

 of moderate weather as clouds, high humidity, 

 and precipitation; this is not often true for man- 



caused fires. Table 15 and figure 53 contain the 

 specific information for the above discussion. 



Why an average no-action lightning fire is 

 only slightly larger than an action lightning fire 

 can lead to many conjectures. A partial explana- 

 tion can be: (1) the more potentially dangerous 

 fires are attacked first; (2) action not taken be- 

 cause known barriers may restrict the fires to 

 small size; and (3) initial attack on some action 

 fires occurs after they have become too large to 

 control; they are subsequently abandoned — 

 hence, large acreages appear on the action fire 

 side of the ledger that otherwise would have 

 been charged against no-action fires. The per- 

 centage of lightning fires upon which no action 

 was taken has been materially reduced since 

 1956. 



Table 15. — Fires receiving suppression action 



Type of fire 



Action 

 status 



Num- 

 ber 



Total area 



burned 



Averag 

 per 



e area 

 fire 



Lightning 



No action 



20 



Acres 

 303,214 



Percent 



Acres 

 15,161 



Ratio 





Action 



41 



549,574 





13,404 







Total 



61 



852,788 



76 



13,980 



10 



Man-caused 



No action 



17 



181,514 





10,677 







Action 



176 



84,828 





482 







Total 



193 



266,342 



24 



1,380 



1 



Total 





254 



1,1 19,130 





4,406 





Monthly Variation in Fire Frequency and Size 



Lightning fires. — Virtually no lightning fires 

 occur before mid-May or after the end of August. 

 Eighty-eight percent of all lightning fires start 

 during June and July. Class D fires are a very 

 small percentage of the total number of lightning 



fires in any one month, but the number of Class 

 E fires is consistently greater than that for any 

 other class (fig. 54). 



Man-caused fires. — The frequency pattern 

 for man-caused fires deviates considerably from 

 that of the lightning fire (fig. 54). For nearly all 



62 



