BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Picea breweriana | Brewer Spruce 



GENERAL BOTANICAL CHARACTERISTICS : 
Brewer spruce is a native, endemic conifer.  It has a distinctive,
drooping appearance caused by the presence of thousands of long,
ropelike branches hanging from all but the topmost horizontal limbs
[14,18,19,23].  At maturity, Brewer spruces usually reaches 80 to 100
feet (24-30 m) in height [16], but can reach up to 172 feet (52 m) in
height [21].  Diameters range from approximately 3.8 feet (117 cm) [18]
to up to 4.5 feet (1.35 m) in some areas [21].  The bark is thin and
broken into long, thin, appressed scales [14,16].

The leaves are obtuse, flat on top, and rounded underneath, and spread
from all sides of the branchlets.  The male cones are stalked and oblong
(3 to 4 inches [7-10 cm] long).  The seeds are 0.12 inch (3 mm) long
[14,16].

The root system generally is shallow; however, on deeper soils, a few
vertical roots may extend several meters [18].

Brewer spruce can live as long as 900 years [21].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
The major regeneration mode of Brewer spruce is by seed [2].  Brewer
spruce is monoecious and begins producing seed at 20 to 30 years of age.
Mature Brewer spruce are apparently fair seed producers [18].  Crops
occur at 2-year intervals, but some trees produce cones yearly [18].
Production of seed ranges between 51,000 and 74,000 seeds per pound
(112,500-163,000 seeds/kg) [18], with a reported average of 61,000 seeds
per pound (134,500 seeds/kg) [16].  Seeds of Brewer spruce require a
stratification period of 30 to 90 days [14,16].  Germinations rates vary
from 50 to 96 percent, with an average of 88 percent [16,18].

Germination is epigeal and occurs on loose soil from upturned roots,
decaying logs, forest humus, and leaf litter under brushfields.
Seedlings are unable to survive strong sunlight and are sensitive to
high moisture stress and temperatures of exposed sites.  First season
epicotyl height growth is less than 0.24 inch (6 mm).  Further growth is
slow, but it appears to be faster on south-facing montane chaparral
[18].  Saplings and pole-sized Brewer spruce average 6 inches (0.15 m)
in annual height growth [18].


SITE CHARACTERISTICS : 
Despite its restricted distribution, Brewer spruce has a broad
ecological amplitude.  Its apparent limitations are high water tables
and frequent fires [17,18].  Brewer spruce is quite tolerant of soil
moisture stress, cold temperatures, low light, low-fertility soils, and
snow [13,18,21].  Although Brewer spruce can tolerate considerable soil
moisture stress, it is sensitive to high evaporation demands.  Under
such demand, stomata close, halting photosynthesis [13,18,21].

Brewer spruce grows in a climate of cold, wet winters and warm,
relatively dry summers with respective temperature ranges of 30 to 41
degrees Fahrenheit (-1 to 5 deg C) and 52 to 68 degrees Fahrenheit
(11-20 deg C).  Annual precipitation varies between 39 and 110 inches
(1,000-2,800 mm) [18].

Brewer spruce stands occur on north-, south-, east-, and west-facing
slopes, but the preferred habitat is steep, north-facing slopes [3,18].
Brewer spruce occurs on rocky ridges [18], cold hollows [14], and on dry
talus and moraines [17].  It never occurs in areas where the
soils are saturated during the growing season, such as boggy or wet
areas.  The slope is generally 11 to 70 percent [18].

Brewer spruce grows on soils developed from sedimentary, granitic,
serpentine, and metavolcanic rock [18].  Most soils are shallow, rocky,
and undeveloped; however, Brewer spruce does occur on deeper soils [18].
Soil pH ranges between 4.6 and 7.2 on mica schist, meta volcanic,
granitic, and ultrabasic soils [21].  Soil depth varies between 12 and
50 inches (6.5-127 cm) [3].  Kruckeberg [9] lists Brewer spruce as an
indicator of serpentine soils.  Heavy metals, especially iron and
nickel, can attain high levels in soil and plant tissues of Brewer
spruce [9].

Brewer spruce occurs at the elevations listed below [3,18]:

                             feet               meters
Siskiyou Region           3,840-5,120         1,163-1,515
Eastern Klamath Region    4,500-7,500         1,370-2,290

The majority of Brewer spruce overstory associates are listed in the
Distribution and Occurrence frame.  Other overstory associates not
mentioned previously include noble fir (Abies procera), sugar pine
(Pinus lambertina), Pacific yew (Taxus brevifolia), and Alaska cedar
(Chamaecyparis nootkatensis) [3,4,8,17,18].  Shrubs that occur in
association with Brewer spruce include Sadler oak, huckleberry oak
(Quercus vaccinifolia), greenleaf manzanita (Arctostaphylos patula),
pinemat manzanita (A. nevadensis), thinleaf huckleberry (Vaccinium
membranaceum), snowberry (Symphoricarpos hesperius), dwarf Oregon grape
(Berberis nervosa), and Labrador tea (Ledum glandulosum) [3,17,18].
Associates that occur in the herbaceous layer are beargrass (Xerophyllum
tenax), western prince's pine (Chimaphila umbellata), vanillaleaf
(Achlys triphylla), rattlesnake plantain (Goodyera oblongifolia),
Pacific trillium (Trillium ovatum), false Solomon's seal (Smilacina
stellata), queenscup (Clintonia uniflora), starflower (Tridentalis
latifolia), and groundsel (Senecio triangularis) [3,4,17,18].


SUCCESSIONAL STATUS : 
Brewer spruce is very shade tolerant and can become established under an
almost closed canopy [18,21].  It is usually occurs in late seral or
climax communities but can also invades seral pine stands and montane
chaparral [17,21].  Toward the eastern limit of its range, stands
dominated by western white pine (Pinus monticola) and Douglas-fir
(Pseudotsuga menziesii) are replace by Brewer spruce-Shasta red fir
(Abies magnifica var. shastensis) climax [21].  Brewer spruce is
restricted to less fertile soils because of strong competition from
other conifers [18,21].



SEASONAL DEVELOPMENT : 
Strobilus buds appear in early summer, accompanied by the shedding of
pollen, at which time the conelets are receptive.  The male strobili
develop from axils of needles of the previous year's shoots.  After
pollenation, the strobili dry and fall from the tree and the conelets
turn down and mature over the summer, into September and October.
Dissemination follows immediately [18].

Related categories for Species: Picea breweriana | Brewer Spruce