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

FOREST TREES OF THE PACIFIC SLOPE. 71
of soil moisture ; best in deep, fresh, porous soils, but thrives on low, moist sites and In
dry, gravelly soils.
Sometimes forms pure stands, but usually in mixed stands. Its best growth is in
northeastern Washington, northern Idaho, and northwestern Montana, where it often
occurs in pure open forests in valleys and slopes. In the Blue Mountains of Washington
and Oregon, on typical fiats. iliere, also, areas of this larch and lodgepole pine are interspersed
through the forest of Engelmann spruce, white and lowland firs, and Douglas
fir ; the silvical characteristics of larch and lodgepole pine appear very similar in view of
common association. Of largest size at lower elevations along Priest River (Idaho), in
mixture with western white pine, western red cedar, Douglas fir, western hemlock, Engelmann
spruce, and lowland fir. It is a more important part of Douglas fir forests somewhat
higher up, where it is associated also with lodgepole and western white pines,
lowland and alpine firs, Engelmarn spruce, cottonwoods, and birches. In Bitterroot
mountains (northern Idaho), in pure stands or with slight admixtures of Douglas fir and
western yellow pine.
CLIMATIC CONxDITIONS.-Seasonal precipitation, from about 20 to about 30 inches,
with a moderately heavy snowfall remaining on ground until summer. Rains frequent
in spring and fall, but summers hot and dry.
TOLERANCE--Very intolerant of shade throughout life; probably demands even more
light than western yellow pine. This intolerance partly compensated for by early rapid
height growth, which carries it above suppressing heavier-foliaged associates. Appears
more tolerant on moist than on dry soils. In moist sites it grows in fairly dense stands,
and is tall, with a clear bole, and its lower branches are early killed and dropped; while
on drier soils open stands or isolated trees occur with branches often retained to the
ground.
REProDncTIoN.-A prolific seeder, but locally variable in seed production; sterile
periods of from one to several seasons are likely to intervene. Rarely bears seeds as
early as the 25th year, but begins to bear prolifically at 40 or 50 years. Seed has a
fairly high rate of germination and moderately persistent vitality. The thin scales of
ripe cones open and close very readily with alternate dry and wet weather, so that the
period and the rapidity of seed dispersion vary somewhat with local climatic conditions.
Usually much seed is shed on snow. Abundant moisture required for germination and
growth of seedlings. The chief competitor of larch is lodgepole pine, both finding suitable
seed beds in burned-over areas with exposed mineral soil, where the kind of reproduction
depends upon whether larch or pine has seeded first. If lodgepole pine has the
start, it shades out the more intolerant larch. If both species start together, larch may
preserve its numerical importance in the stand by more rapid growth. Its light foliage
can not prevent the growth of the pines, or of spruce and firs, and the typical occurrence
of larch in mixed stands is a result. Favorite areas for pure larch reproduction
are those so thoroughly burned over as to preclude the immediate heavy reproduction of
lodgepole pine.
Alpine Larch.
Larix lyallii Parlatore.
DISTINGUISHING CHARACTERISTICS.
The strictly alpine habitat of Alpine larch serves very largely to distinguish
It from the Western larch, which it resembles in some features. It is stunted in
appearance, from 30 to 40 feet high and froat 10 to 24 inches in diameter, with a
long, broadly pyramidal, pointed crown. Some of the branches are very long and
big, forming an open unsymmetrical crowl. Somewhat larger trees are sometimes
found. As a rule, the ends of the branches turn upward, but frequently
they droop conspicuously, while, in contrast with the brittle branches of Western
larch, they are tough and withy. A notable character of the new branch shoots
is their dense coating of white, fine wool, which is retained, more or less, for
two seasons, and from which the tree gained the name of " woolly larch."
Trunks are clear of branches for only about one-third or one-half the tree's
height, and, as a result of exposure, are often crooked or bent. The bark of
mature trees is rarely more than seven-eighths of an inch thick. It is indistinctly
furrowed; the irregular, flat ridges of loose scales are deep purplish or
reddish brown. On young trees the bark is usually unbroken until they are 5
or 6 inches in diameter. Previously it is ashy gray, as are the crown branches
of older trees. The foliage is distinctly light bluish-green, turning bright lemon-