1012 



Canadian Forestry Journal, March, 1917 



can safely be cleared for farming if the rest of the area is left in forest. Failure 

 to recognize this fact and to retain the forest where its protective influence 

 is needed has been the direct cause of niuch unnecessary wasting of the soil. 



Far-reaching Evils of Fire 



Among the many evils chargeable to forest fires, their effect on the char- 

 acter of the run-off is by no means the least. Their tendency is in the same 

 direction as clearing — to decrease the amount of water absorbed and con- 

 sequently to increase surface run-off and soil washing. 



From the standpoint of erosion every fire on hilly land is a menace — 

 the steeper the slope the more serious the menace. Conflagrations which 

 completely destroy the cover are, of course, most dangerous. Even light 

 surface fires, however, are not to be disregarded. By destroying the humus 

 and the carpet of weeds and other plants, these tend to harden the soil and 

 to reduce materially its absorptive capacity. Repeated fires on the same 

 area are particalarly dangerous, since they gradually open up the stand, re- 

 move all trace of vegetable matter, and may cause the soil to harden and 

 pack so as to be almost impervious. One or two specific examples may help 

 to make clear the damage that may be done by even a single fire. 



Two Graphic Examples of Erosion 



On the north side of the Soleduck Valley, in western Washington, some 

 12,000 acres were severely burned in 1907. All vegetable growth was de- 

 stroyed and all soil cover removed. Very little vegetation started in the 

 first four years following the fire, and during these years the slopes were sub- 

 jected to considerable erosion. Soil and fragments of stone were carried 

 in great quantities to the many gulches and water courses. In November, 

 1910, a combination of heavy snow, followed by a ch-inook wind and a warm 

 rain, caused an enormous run-off of water, carrying with it great quantities 

 of soil and rock. This shifting mass was so great that most of the creek 

 channels, where they struck the flat, became choked with it and built up 

 fan-shaped deltas, in some cases several acres being covered with debris from 

 1 to 6 feet deep. Even now erosion on these areas is considerable, although 

 not nearly so great as during the first few years after the fiie. 



In the brush-covered fcothills of southern California, near the town of 

 Piru, is' a small watershed of perhaps 1 squai'e mile known as "Nigger Can- 

 yon." . In October, 1912, approximately 100 acres of this were burned over 

 and the' cover completely destroyed. The following January a series of heavy 

 rains caused unprecedented erosion on the area. Rocks from 2 to 2i^ feet 

 in diameter, so large that they could hardly be moved by a team, were brought 

 down by the flood^ Ten acres of orange orchard near the mouth of the can- 

 yon were covered with a deposit of gravel from 6 inches to 5 feet in depth, 



REPAIRING EARLY MISTAKES 

 Drifting sand in Norfolk County, Ontario, planted up with evergreens from the Ontario forest 

 nursery. This land ougl^t to have been retained permanently under forest. 



