CANADIAN FORESTRY ASSOCIATION. 19 



it may cross over to the opposite slope. The burnt areas are therefore usually re- 

 stricted in dimensions, but on the other hand they are discouragingly numerous. So 

 numerous are the fires in a dry season that the whole countryside may be buried 

 under a dense pall of smoke. Last summer in the Lardeau-Duncan district, where I 

 was engaged in field work, no topographical work could be done during the whole of 

 August and September. Often objects, no matter how large, were invisible a hundred 

 'yards away. 



The extent of the damage done to the timber by fires varies. Occasionally a fire 

 may burn out the underbrush without absolutely destroying the timber, and such 

 standing timber may remain sound for years. The Cascade river, near Banff, was 

 swept by fire twenty-five years ago. Some of the burnt timber is still standing, but 

 most is now down. Professor J. C. Gwillim informs me that it is still so sound as to 

 be used for timbering the coal mines. Dr. G. M. Dawson, in 1886, speaks of the upper 

 valley of the south fork of Sheep creek being a desolation of bleached fire-killed tim- 

 ber. In 1904 some of this was still standing, and a large amount sound. 



In a dry season like last the fire is apt to consume everything. Last summer I 

 climbed up a hillside through fine green timber, and about a week later came down 

 the same place wading knee-deep in ashes. Not a vestige of anything combustible on 

 or in the soil had been left. The hillside was as bare as the bottom of an alkali pond. 

 I ran across several fires that had been equally thorough. 



When a fire gets well under way only a protracted wet spell will stop it. So long 

 na the interior of rotten logs and the roots remain dry it will smoulder until condi- 

 tions are once more favourable, when it will again break forth. 



CAUSES. 



Not all the fires originate ^through human agency. Electric storms are an im- 

 portant source. In 1903 during one thunderstorm I saw through the door of the tent 

 four fires start, and altogether from the camp I counted eight. Fortunately this 

 storm was succeeded by several days of heavy rain, so that little damage was done. 

 Electric storms unaccompanied by rain are not unknown in the high mountains dur- 

 ing the dry season. One summer we had to strike camp and rush for safety from a 

 fire which suddenly and without warning was started by an electric discharge from a 

 clear sky, and which rapidly enveloped the whole mountain side. I have frequently 

 seen traces of such fires. So far as my observations go, such storms are usually con- 

 fined to the higher altitudes. Here the timber is isolated in groves, so that such fires 

 do not usually become large. 



The greater number of the destructive fires are started by human agencies. If 

 p.ny proof of this were needed it would be furnished by the fact that on the whole the 

 forest tmatures and is preserved until man white man and his retinue gets into a 

 district, and then the destruction greatly exceeds the natural recuperative powers of 

 the forest. 



Most of the fires started by man are not accidental, but the result of gross, often 

 wilful, carelessness, and not a few of deliberate intent. In dry seasons, when the grass 

 and moss are like tinder, a match thrown down, especially a wax one, is a source of 

 danger. Camp fires even when extinguished with water may still smoulder in rotten 

 logs, mould or roots, and eventually break forth. 



Smudges built for horses during the fly season are a more fruitful source of fires, 

 for they are generally built large, so as to require little attention, and to accommo- 

 date a large bunch of animals. An increase or change in the wind during the day 

 may start a fire that before it receives attention is quite beyond control. It is of 

 course during the dry season that such smudges are required. In 1902 I came upon 

 a very destructive fire in the Boundary district that had originated in this way. The 

 same season, from the top of a mountain on which we were taking a survey station, 

 we saw a spark from a locomotive start a fire in the dry grass. Shortly after the sec- 

 tion gang passed it on their way home. In five minutes they could have put it out. 



113982* 



