BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Picea sitchensis | Sitka Spruce 



GENERAL BOTANICAL CHARACTERISTICS : 
Sitka spruce is a native, long-lived (greater than 800 years),
evergreen, monoecious tree [24,55].  Female strobili are produced at the
ends of primary branches near the top, while the male strobili are
positioned lower in the tree on secondary branches [24].

Sitka spruce is the world's largest spruce.  It can obtain heights of
greater than 210 feet (65 m) with a d.b.h. of 16 feet (5 m) on better
sites [24].  The base of the bole is buttressed [55].  When forest grown
the bole is long and free of lower limbs [23].

The root system of Sitka spruce is shallow and platelike with long
lateral roots with few branchings.  On deep well-drained soils the root
system may reach depths of 6.5 feet (2 m), especially on alluvial soils.
Root grafting often occurs between roots of the same tree and adjacent
trees [22,24].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sitka spruce reproduces both sexually and asexually.  Sexual maturity
varies from 20 to 40 years.  Dispersal of seeds is moisture dependent;
when the ripe cones dry the seed is dispersed, and when the cones become
wet again they close.  To avoid loss of seed, cones should be collected
soon after ripening [50].  The seeds are small with a mean of 210,000
cleaned seeds per pound (467,000/kg) [24].  The germination rate is 54
percent, but this can be raised to 66 percent by moistening the
germination medium with a 0.2 percent potassium nitrate (KNO3) solution
[50].

Germination is epigeal.  Sitka spruce seed will germinate on almost any
substate, although mineral soil or a mixture of mineral soil and organic
soil are considered the best seedbeds [24].  The "nurse log syndrome"
has a key role in the regeneration of Sitka spruce in its wetter
environs [12,15,20].  Germination and seedling survival are greater on
rotting logs then on the forest floor.  In a germination study less than
1 percent of the seeds in a moss mat germinated, and of these 38 percent
were killed within a month by fungi [21].  Nurse log syndrome results in
a "colonnade" where there are several trees in a row with the roots
supporting the bole in mid-air after the nurse log has rotted away [5].

Seedling establishment and growth can be enhanced with the inoculation of
the mycorrhizal fungi, Thelephora terrestris [10,40].

Sitka spruce shows strong trends in hardiness and growth in relation to
geographic origination.  These trends can be used to increase growth
rate, but they can also have adverse effects on survival [22,38].
Lester and others [38] provide information on seed sources, outplanting
results, hardiness, and growth rate trends.

Sitka spruce reproduces asexually by layering.  This usually takes place
in moist areas or at timberline [22,24,31,55].  Cuttings from current
year's growth root more readily than older branches [24].


SITE CHARACTERISTICS : 
Sitka spruce occurs in the hypermaritime to maritime cool mesothermal
climates [32,33].  It occurs from shoreline to timberline in the
northern portion of its range but is restricted to shoreline in the
southern portion of its range [6].  Sitka spruce grows best on sites
with deep, moist, well-drained soils [22].  It can tolerate the salty
ocean spray of seaside dunes, headlands, and beaches, and the brackish
water of bogs [34].  Stika spruce is limited to areas of high annual
precipitation with cool, moist summers [16,23].

Soil:  Sitka spruce has a stong affinity for soils high in calcium,
magnesium, and phosphorus in the soil orders Entisols, Spodosols,
Inceptisols, and Histosols.  These soils are usually acidic with pH
typically ranging from 4.0 to 5.7 [24].

Elevation:  Sitka spruce grows from sea level to timberline in Alaska (0
to 3,900 feet (0-1,189 m)) [55] with elevational limitations of 2,000
feet (600 m) in Washington and 1,500 feet (450 m) in Oregon and
California [5].

Associates:  In addition to those listed under Distribution and
Occurrence, Stika spruce's overstory associates include mountain hemlock
(Tsuga mertensiana), Alaska-cedar (Chamaecyparis nootkatensis),
lodgepole pine (Pinus contorta), and western white pine (P. monticola)
[24].

Understory associates include western swordfern (Polystichum munitum),
false lily-of-the-valley (Maianthemum dilatatum), stream violet (Viola
glabella), evergreen violet (V. sempervirens), red huckleberry
(Vaccinium parvifolium), devils club (Oplopanax horridum), salmonberry
(Rubus spectablis), and thimbleberry (R. parviflorus) [24].


SUCCESSIONAL STATUS : 
Sitka spruce is a shade-intolerant species [33] that is both a pioneer
and a climax species [22].  Sitka spuce acts as an early pioneer on the
undeveloped soils of landslides, sand dunes, uplifted beaches, and
deglaciated terrain; it is a climax species in the coastal forests [22].


SEASONAL DEVELOPMENT : 
Flowering and seed dispersal dates for Sitka spruce in Alaska and Oregon
are as follows [22,50]:

         Flowering       Fruit Ripens                  Seed Dispersal

Alaska   April to June   late Aug. to mid-Sept.        Starts in Oct

Oregon   May                  Aug                      Oct. to Spring

Seed dispersal is moisture dependent; when the ripe cones dry dispersal
begins.  The majority (73 percent) of seed are dispersed in the first 6
weeks; the remainder are released over the next year [22].

Related categories for Species: Picea sitchensis | Sitka Spruce