to several thousand or even to several hundred 

 thousand acres. Seventy-four percent of all fires 

 in Interior Alaska burn in the highly flammable 

 spruce and tundra types. The final size of a 

 lightning fire averages 10 times the size of a 

 man-caused fire primarily because lightning fires 

 are common in the Interior Basin, but detection 

 and access are both difficult. During the period 

 of analysis 33 percent of lightning fires and 9 

 percent of man-caused fires never receive any 

 control action. These figures include many fires 

 extinguished by nature before action could be 

 taken; also, action is not taken on fires on pri- 

 vate or entry land unless real danger to adjacent 

 public lands develops. Fires on which no action 

 was taken account for 35 percent of acreage 

 burned by lightning fires and 68 percent of acre- 

 age burned by man-caused fires. Eighty percent 

 of all lightning fires occur in June and July; but 

 73 percent of the acreage burned by these light- 

 ning fires is burned in June. Fifty-seven percent 

 of man-caused fires occur in May and June; but 

 70 percent of all acreage burned by these man- 

 caused fires is burned in May. In general, as 

 the total number of fires increases, the number of 

 Class E fires (more than 300 acres) also increases, 

 and the number of Class A fires (less than one- 

 fourth acre) decreases; early overloading of a 

 small suppression force may account in part for 

 this. 



Most man-caused fires occur near popula- 

 tion centers, as would be expected. More than a 

 usual number of reported lightning fires also 

 burns in a somewhat similar pattern,- the distri- 

 bution will no doubt appear different when 

 better detection and reporting procedures are 

 developed. 



Southeastern Alaska has not been treated 

 in this analysis because fire conditions there are 

 not as critical as in the Interior. An average of 

 26 fires — virtually all man-caused — occurs 

 annually in southeastern Alaska and burns about 

 638 acres, or 25 acres per fire, compared to 4,400 

 acres per fire in Interior Alaska. However, the 

 fire potential in southeastern Alaska is increas- 

 ing as logging activity increases. 



Virtually no specific data were available 

 describing the behavior of wildfires in Alaska 

 prior to 1958. During 1958 and 1959, fire be- 

 havior teams collected data on the fireline from 



19 fires. The teams measured rates of spread, 

 weather factors, and fuel variations, and ob- 

 served their interrelationships. The primary ques- 

 tion to be solved was, "Why do fires in Interior 

 Alaska get so large so fast?" The most probable 

 explanation of the behavior of seven of these 

 fires is briefly summarized below: 



1. Healy: High winds resulting from topo- 

 graphic features. 



2. Murphy Dome: Broken topography, high 

 burning index, thunderstorms, and atmospheric 

 instability. 



3. Kenai Lake: Steep topography causing 

 diurnal wind reversals; frontal movement pass- 

 ing over area. 



4. Colorado Creek: Highest burning in- 

 dexes of all fires studied; topography altered 

 winds. 



5. Lake 606: Strong winds, thunderstorm 

 downdrafts. 



6. Stony River: Unbroken horizontal fuel 

 continuity,- frontal movement. 



7. Huggins Island W-10: Rough topog- 

 raphy; variable and gusty surface winds due to 

 atmospheric instability. 



Data from these fires indicate that nearly 

 all extreme behavior can be explained qualita- 

 tively but not quantitatively at present. Impor- 

 tant problems in fire control are: (1) forecasting 

 fire-weather conditions, (2) predetermining fire 

 behavior, and (3) determining the influence of 

 different fuels on rate of spread under various 

 weather regimes. 



Organized forest fire control in Interior 

 Alaska began in 1939 with an appropriation of 

 $37,500. The high potential value of the timber 

 resource is now receiving more nearly adequate 

 recognition,- but even so, a comparison of the fire 

 control organization in Interior Alaska with that 

 of Region 1 of the U.S. Forest Service (Montana, 

 northern Idaho, northeastern Washington, and 

 northwestern South Dakota) reveals there is still 

 a long way to go before an adsquate fire con- 

 trol organization is achieved. The Bureau of 

 Land Management in Interior Alaska protects 

 seven times as much area, has one-fourth as 

 many fires, and fights them with 1 1 percent 



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