De I. VNER VEW D Forest Trees of the Pacific Slope

FOREST TREES OF THE PACIFIC SLOPE.
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The detailed range of alpine fir in the Rocky Mountain region will be dealt
with in a later bulletin.
OCCURRENCE.
In cool, moist, and, in part, subalpine situations; commonly on slopes at timber line,
and at its lower limits in protected valleys, at heads of streams, and about mountain
lakes and meadows. Best growth on fairly deep, loose, moist soil ; will grow also in
wet and on poorest and driest thin soils. Main occurrence limited by requirement of
soil moisture to elevations where snowfall is great. Requires less soil moisture in
general than Engelmann spruce, but grows in places too wet for the spruce, as well
as on Douglas fir soils, where spruce will not succeed. Does not thrive on heavy,
clayey soils. Altitudinal occurrence in Alaska narrow, owing to low timber line; more
abundant on east than on west slopes of Alaskan coast mountains. Throughout north
coast ranges and the Rocky Mountains the vertical range is wide. tlere on all slopes,
but largest on high north aspects. At south, attitudinal extent is again narrow, because
favorable moisture occurs only at much higher elevations.
In pure, small stands and in mixture. In Alaska, mainly with black hemlock; at
higher levels in Washington, with black hemlock, occasionally yellow cedar anld whitebark
pine, and lower, with noble and amabilis firs; in Oregon, with black hemlock,
Engelmann spruce, western white pine, lodgepole pine, and noble fir.
CLIMIATIC CONDITioNs.-Endures rigorous climate, and therefore it goes farther north
than any other coast fir. At far north, subject to blighting winter winds, weak insolation
due to high latitude and extreme cloudiness, excessive precipitation, averaging over
60 inches of rain and from 2 to 5 feet of snow, and also to minimum temperature
of about -40' F. At south, sunlight is more abundant, lower humidity and smaller
precipitation-averaging about 25 inches and mainly snow. Maximum temperature, about
900 F.
TOLERANCE.-Only slightly less tolerant of shade than Engelmann spruce, and more
so than other associated species (except black hemlock) ; maintains long-suppressed
reproduction under heavy shade, and with admission of light recovery and growth are
rapid.
REPRODUcTION.-Moderately prolific seeder. Seed with rather high rate of germination,
but of transient vitality. It begins to bear cones as early as the twentieth year.
P'roduces some seed locally every year, with heavy production at intervals of about three
years. Over large areas, however, cones often fail to mature during some seasons.
Reproduction usually abundant, both in open on exposed mineral soil, and on thin and
heavy moist duff under light or heavy shade. Seedlings grow most thickly on north
sides of groups or forests and under branches of mother trees; small shaded openings
among seed trees nearly always show reproduction. Occasionally at high elevations
branches tying on ground take root (layer), from which, however, reproduction is
probably rare.
Grand Fir; White Fir.
Abics granotids Lindley.
DISTINGUISHING CHARACTERISTICS.
Grand fir is commonly called 'white" fir because of its conspicuously whitish,
smooth bark. Other firs of the same region are known as " white" firs of a
"different variety," especially Abies concolor, to which the name "white fir "
appears to belong more fitly than to any other. It is desirable, therefore, for
the sake of a distinctive common name, to coin for Abies granldis the name of
" grand fir," which is appropriate, since it is a very stately and grand tree when
fully matured. It grows to a height, in such favorable situations as bottomlands,
of from 150 to 200 and, exceptionally, 250 to 275 feet, with a diameter of from
3 to 4 feet. On the less favorable hill lands its greatest height is from 80 to
125 feet, with a diameter of from 18 to 30 inches. Its trunks are remarkably
straight and very gradually tapered. Standing alone or in an open forest, it
carries its crown branches to within a few feet of the ground even when old,
but in a close stand the crown covers only one-half or one-third of the stem.
The crown is a narrow, rather open cone, pointed in young trees, but in old age
is somewhat rounded at the top, and often, from the strong drooping of the
lower branches, appears wider in the middle. The rounded top results from