1905] WHITFORD—FORESTS OF FLATHEAD VALLEY 291 
if the interval between the fires is sufficiently long to give lodgepole 
pine time to produce seeds, after each fire a forest of lodgepole pines 
will spring up to replace the old. Such fires enable lodgepole pine 
to perpetuate itself- so 
long as the soil is able 
to furnish the requisite 
amount of nourish- 
ment, but a checking of 
fires will in time bring 
about the normal con- 
ditions. This has been 
done about as follows: 
The fires being 
absent, the lodgepole 
pine stand is permitted 
to reach maturity. As 
it does so, seeds of forest 
trees in the neighbor- 
ing undestroyed or par- 
tially destroyed stands 
have had time to spread 
into the lodgepole pine 
forests. Seedlings of 
those trees that can 
tolerate the shade will 
et a start at once, if 
the other conditions are 
favorable. Thus in 
Many instances silver 
Pine, lowland fir, and 
Engelmann spruce were 
hoted growing under 
lodgepole pine stands 
in Swan valley. Also in 
ae Shae Lake r region 
: ea 
10f western larch, Douglas 
FIG 22.—Young growt : h : 
S “ol i -learing I the same 
= a clea nf Oo 
spruce, and bull pine in ~ 
i : , PRAEGER. 
species.—Photograph by PRA! 
Ss, alth ug € hey | S c re a to W hich 
