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

FOREST TREES OF THE PACIFIC SLOPE.
Oregon to over 100 inches in British Columbia and Alaska. Temperature occasionally
-350 F. on west slope of Rockies in north Idaho, Montana, and British Columbia,
and also in parts of Alaska, but elsewhere, especially in coast regions south of
Alaska, well above zero. This hemlock generally follows humidity and precipitation
of the region. Precipitation and humidity decrease from the coast to the Rockies.
Precipitation is much less on east side of coast ranges and Cascades than on the
sea slopes; deficient in interior basins of Oregon, Washington, and British Columbia
between Rockies and Cascades; abundant on west slope of Rockies.
TOLERANCE.-Very tolerant of shade throughout life, especially in seedling stages. In
later life vertical light necessary for best growth. Allowed overhead light, it recovers
remarkably well from long suppression and renews rate of growth. Prolonged suppression
in dense shade greatly checks growth. Thrives in cool, open, humid places
with abundant soil moisture. Maintains dense stands, alone, subordinate to others, or
as dominating tree with equally tolerant or slow-growing species.
REPRODUJCTION.-Very prolific seeder, reproduces itself freely everywhere under favorable
conditions. Produces some seed every year, but heavy seed years occur at irregular
intervals. Seed with moderate rate of germination and moderately persistent vitality.
Germination excellent and growth of seedlings good on wet moss, humus, litter, decaying
wood, muck, and mineral soils-the latter less favorable than moist vegetable seedbed.
Reproduction abundant under dense shade of mature stands and also in the open
on cut-over areas with favorable moist forest floor. Restocks burned over areas at first
only sparingly, where light-demanding Douglas fir, pine, larch, fir, etc., come in first.
Mountain Hemlock; Black Hemlock.
Tsugtt mertensiana (Bong.) Sargent.
DISTINGUISHING CHARACTERISTICS.
Mountain or black hemlock, an alpine tree, has little general resemblance to
the better-known western hemlock. Only the drooping slender branches and
its bark suggest hemlock to the casual observer, by whom its foliage might be
easily mistaken for that of spruce, or possibly of fir. Forest-grown trees have
sharp-pointed, narrowly pyramidal crowns of slender, conspicuously drooping
branches; the upper third of the crown has very short drooping branches, while
the exceedingly slender whip-like leaders are gracefully pendulous. Trees grown
in the open bear branches of the same habit down to the ground, rarely losing
them for more than a few feet above ground, even in old age. Ordinarily,
mountain hemlock is short, from 25 to 60 feet high and from 10 to 20 inches in
diameter; the trunk is often rather sharply tapering; on bleak crests, it is only
a few feet high or sprawling on the ground. Trees 75 or 80 feet high are not
uncommon, while trees 100 or 125 feet high, with a diameter of 30 or 40 inches,
are sometimes met with. On high, steep slopes the trunks are strongly bent
down the slope at their bases, in the form of a sled-runner. Heavy snows
annually bend or crush the slender seedlings and saplings to the ground without
killing them and later growth rarely straightens the bent stems. The bark is
early broken and rough on young trees. That of old trees is about 1U inches
thick and dull purplish to dark reddish brown. It is deeply and narrowly furrowed;
the rough, hard, distantly connected ridges are narrow and rounded. At
some distance the trunks have a blue-gray tinge. The dense foliage varies from
a dark to a pale blue-green. Foliage of a season's growth is shed about the
fourth year. The blunt-pointed leaves (fig. 35) are rounded and plump looking,
in this respect unlike the flat leaves of other hemlocks, but like them the leaves
have small distinct stems. They clothe the branches all around, but appear
thicker on their upper sides. The main branchlets are unique in having numerous
short, erect side branches; both are minutely downy for several years. The
cones are full grown in one season. They are usually so abundant as to almost
cover the branchlets and to bend them down with their weight. Usually they
are pendulous; very rarely, and chiefly on stunted trees in exposed situations, the
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