18 BULLETIN 1200, U. S. DEPARTMENT OF AGRICULTURE. 
and at 900° F. the fire spreads rapidly through green needles. A 
comparison of these figures shows that mature seed would live 
through the fire if the seed were in cones on the trees. 
ORIGIN OF YOUNG GROWTH. 
In the Douglas-fir region of Oregon and Washington conditions 
are little less than ideal for the replacement of the forest by natural 
means, providing the harvesting of the crop and fire protection are 
properly managed. The Douglas fir can dominate all its competitors 
in this region, except under unusual conditions, and these conditions, 
fortunately, can be controlled by man. Fire is the most destructive 
agent at work in the forests, and yet it is responsible for retaining 
the Douglas-fir forests in some localities. The effects of fire on the 
Douglas-fir forests have been determined by a thorough analysis of 
the results of various types of forest and slash fires. Some of the 
most terrific fires of the Pacific Northwest have failed to wipe out 
the Douglas-fir forests, and splendid stands of young growth now 
clothe the areas that were burned. 
DISTRIBUTION OF YOUNG GROWTH AFTER ONE FIRE IN A 
MATURE FOREST. 
The Columbia burn (locally known as the Yacolt burn) afforded 
an excellent opportunity for the study of the origin and distribution 
of young growth following a single fire in a mature forest. The 
Columbia fire burned northward from:the Columbia. River in the 
Columbia National Forest in southern Washington over an area of 
about 250,000 acres in the western foothills of the Cascade Moun- 
tains at elevations of 500 to 4,000 feet (Pl. III). At the lower alti- 
tudes the forest traversed by the fire was the Douglas-fir type, which 
includes Douglas fir, western hemlock, western red cedar, western 
white pine, and grand fir (Abies grandis Lindl.). Above 1,100 feet 
silver fir makes its appearance, and then noble fir; and at about 
3,000 or 3,500 feet the forest develops into the true fir type, com- 
posed almost entirely of noble and silver fir, with a shght admixture 
of western white pine and Douglas fir. Pacific yew (Taxus brevi- 
folia Nutt.) is distributed almost throughout the forest, avoiding 
only the subalpine summits of the higher ridges. Dwarf juniper 
(Juniperus communis L.), on the other hand, is restricted to the sub- 
alpine summits. ) 
The fire occurred from September 8 to 12, 1902, following an 
exceptionally dry season, and driven by a dry southeast wind it 
traveled to the northwest. So far as can be determined from local 
information it progressed at a maximum rate of perhaps 8 miles 
an hour during the time it was doing the most damage. No portion 
of the area studied had been burned over by a second fire. The burn 
was studied 11 years after the fire occurred. 
The main feature of interest found on the burn was the good 
stand of young growth which almost uniformly covered the area and 
consisted of the same species as those which made up the burned 
forest. The presence of this reproduction is obvicus to anyone 
passing through the area, but the reason for its appearance after so 
severe a fire has always been open to conjecture. The problem, 
then, was to determine the history of the reproduction and, so far as 
possible, to account for its distribution. 
