VALUE AND USE
SPECIES: Tsuga mertensiana | Mountain Hemlock 



WOOD PRODUCTS VALUE : 
Mountain hemlock is largely inaccessible because of the high altitudes
at which it occurs and is unimportant as commercial timber [71].  It is,
however, harvested to a limited extent near its lower limits; the wood
is generally marketed with western hemlock [71,4].  The wood is
moderately strong and light colored and is most often used for
small-demension lumber and pulp [49].  The wood is also used for railway
ties, mine timbers, interior finish, crates, kitchen cabinets, and
flooring and ceilings [71].  Nearly pure stands of mountain hemlock on
Prince of Wales Island have been logged for pulp [71].


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
Mountain hemlock stands provide good hiding and thermal cover for many
wildlife species [8,45].  Sites dominated by mountain hemlock provide
important summer range for deer in Alaska and Vancouver Island because
of abundant nutrient-rich forbs available in the understory [19,49].  In
Montana, mountain hemlock habitat types provide summer range for mule
deer, elk, and bear [57].  Mountain hemlock seeds have been found in the
stomachs of crows and grouse [70].


PALATABILITY : 
NO-ENTRY


NUTRITIONAL VALUE : 
NO-ENTRY


COVER VALUE : 
NO-ENTRY


VALUE FOR REHABILITATION OF DISTURBED SITES : 
Mountain hemlock is important for watershed protection [49].  The
mountain hemlock/blueberry (Vaccinium spp.)-copperbush (Cladothamnus
pyrolaeflorus)/deer cabbage (Fauria crista-galli) association in Alaska
captures runoff from snowmelt [19].  Planted stock of mountain hemlock
does not perform well.  In high-elevation regeneration trials in the
Vancouver forest region, its performance was poor compared to that of
the other high-elevation species.  Natural regeneration may perform
better [63].


OTHER USES AND VALUES : 
Mountain hemlock is often used as an ornamental for landscaping in the
Pacific Northwest and throughout Great Britain [42,49,4].  Its dense,
compact foliage coupled with its slow growth make it ideal as a garden
evergreen [42].  Hemlock species (Tsuga spp.) played a supernatural role
as magical objects in the mythology of the Thompson and Lillooet
Interior Salish of British Columbia [66].


MANAGEMENT CONSIDERATIONS : 
Insects and disease:  Mountain hemlock is very susceptible to laminated
root rot (Phellinus weiri) [20,49].  In the high Cascades of central
Oregon mountain hemlock is the most susceptible tree.  This fungus
spreads from centers of infection along tree roots so that all trees are
killed in circular areas that expand radially.  Laminated root rot moves
faster through a nearly pure stand of mountain hemlock than through a
more heterogeneous conifer stand.  Growth and coalescence of laminated
rot root pockets in mountain hemlock have produced infected areas of
more than 100 acres (40 ha).  Seedlings are not susceptible to
reinfection by laminated root rot for 80 to 120 years.  This may be due
to greater vigor caused by higher levels of available nitrogen, higher
temperatures, and more growing-season moisture in this regrowth zone
[49].

Other common fungal and parasite pests of mountain hemlock include
several heart rots, of which Indian paint fungus (Echinodontium
tinctorum) is the most common and damaging; several needle diseases;
snow mold (Herpotrichia nigra); and dwarf-mistletoe (Arceuthobium
tsugense) [49].

Mountain hemlock is an occasional host for the western spruce budworm
(Choristoneura occidentalis) [14].

Frost tolerance:  Mountain hemlock is very frost tolerant [41].

Wind damage:  Because mountain hemlock is shallow rooted it is very
susceptible to windthrow.  In the coastal strip of British Columbia and
Alaska, wind commonly destroys mountain hemlock by uprooting it.  As
cutting is increased in mountain hemlock forests, windthrow will
probably become a more common cause of mortality [49].

Silvicultural considerations:  Many sites dominated by mountain hemlock
are particularly difficult to reforest following clearcutting.  In the
Gifford Pinchot, Mount Hood, and Willamette national forests, field
observations showed that the mountain hemlock/big huckleberry/beargrass
and mountain hemlock/grouse whortleberry associations are particularly
difficult to reforest due to a short growing season in a harsh
environment.  Artifical reforestation within 5 years following
clearcutting and burning on these sites may not be possible [35].

The deep, persistent snowpack; short, cool growing season; and poorly
developed soils make regeneration difficult and productivity low for the
mountain hemlock series of the Siskiyou region of southwestern Oregon.
When mountain hemlock stands are managed for timber production, the
following silvicultural considersations are important [8]:

(1) Advanced regeneration and subsequent natural regeneration may
provide the most reliable source for a new stand in 5 years.  Protection
from damage during harvest is essential.  Damaged regeneration is very
susceptible to rot.

(2) Natural regeneration after harvest establishes sooner in small
openings than large openings and is often most rapid on the shaded south
edges of clearcuts.  Keeping clearcuts small to maximize these edge
effects will probably speed regeneration, but it may still be
unsatisfactory in 5 years.  The shelterwood system can provide adequate
regeneration in 5 to 10 years.

(3) Planting has been ineffective on these cold, snowy sites.  Timing is
critical for articifical regeneration.  Plant soon after snow melts.

In British Columbia, the recommended silvicultural method for harvest of
old-growth mountain hemlock is clearcut followed by natural
regeneration.  For young natural stands that have developed after fire
or second-growth stands that have developed after clearcutting, the
clearcut method with natural regeneration, seed tree method, or
shelterwood method is recommended [72].

Related categories for Species: Tsuga mertensiana | Mountain Hemlock