NATURAL REGENERATION OF DOUGLAS FIR. 27 
A fire that occurred near Guler, Wash., on September 2, 1915, ran 
through the crowns of medium-aged Douglas-fire trees that were 
heavily laden with mature cones, and killed but did not burn them 
severely. At the same time, a severe ground fire burned the deep 
layer of litter and duff and undoubtedly heated the soil sufficiently to 
destroy practically all of the seed stored in the forest floor. Counts 
of young growth two years later showed that there were 17,600 
Douglas-fir seedlings per acre, and 98.8 per cent of them came up the 
first year after the fire. Under these conditions, sometimes found 
after large forest fires, the young growth may come from seed in the 
cones at the time of the fire. That seed will live in cones during a 
crown fire has been proved experimentally. (PI. V, fig. 1.) 
If a ground fire occurs in a mixed forest of Douglas fir, western 
red cedar, and western hemlock, when the mature seed is on the trees, 
usually the greatest part of the resulting young growth is western red 
cedar and western hemlock, because of the large amounts of seed pro- 
duced by these species as compared with Douglas fir. The dense 
stand of seedlings may survive through the first season, but in the 
succeeding years the Douglas fir is severely handicapped. If the 
scorched canopy of the forest remains even for a year after the fire, 
the shade is too dense for the Douglas fir seedlings to gain a foot- 
hold, and they are crowded out of the stand. The mature Douglas 
fir trees generally are not killed by this type of fire on account of the 
thick root bark at the crown of the roots, but the thin bark at the root 
crown of the western red cedar, western hemlock, noble fir, and silver 
fir leaves these species easy victims. The remaining green Douglas- 
fir trees may continue to produce seed, but the shade of the dead and 
living trees is too dense for the success of the Douglas fir seedlings. 
Consequently the shade-enduring species, such as western red cedar 
and western hemlock, have the advantage; an understory of these 
species develops and ultimately changes the forest to the cedar- 
hemlock type. (Pl. V, fig. 2.) 
In places where a ground fire has occurred, counts on plots have 
shown stands containing more than 1,000,000 seedlings, 1 and 2 years 
old, to the acre, with only 5 to 10 per cent of Douglas fir. The 
Douglas-fir seedlings were tall and weak, and seemed to have little 
chance of survival, and observation in later years showed that they 
did not survive. 
SEED STORED IN THE FOREST FLOOR IS THE PRINCIPAL SOURCE 
OF YOUNG GROWTH THAT FOLLOWS AFTER ONE FOREST FIRE. 
Although young growth from different sources of seed follows 
after various types of forest fires, the seed in the forest floor before 
the fire is obviously the most important factor in restocking the 
burned areas. As a general rule, restocking may be expected after 
a single burn; but such factors as soil, condition of forest floor, and 
type of fire may cause exceptions to the rule. The general restock- 
ing after one burn is shown in the summary of a representative num- 
ber of transects that were taken in areas burned under different con- 
ditions and in different places. This summary appears in Table 12. 
The averages are based on the number of seedlings found in each 
chain-length of transects that were run from the edge of green timber 
to a distance of 120 chains out into the burns. 
