BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Gaultheria shallon | Salal 



GENERAL BOTANICAL CHARACTERISTICS : 
Salal is an erect to spreading, clonal evergreen shrub or subshrub which
grows 1.3 to 10 feet (0.4-3 m) in height [16,67,80,98].  This loosely to
densely branched shrub often forms dense, nearly impenetrable thickets
[45].  Stems are pilose to hirsute [67] and branchlets glandular to
pubescent [98].  Twigs are reddish-brown with shredding bark [130].
Most biomass is concentrated below ground [102] and an extensive, but
variable network of roots and rhizomes [24] occupies the top layer of
soil [79].

Leaves are ovate to ovate-elliptic, sharply serrulate, and 2 to 4 inches
(5-10 cm) in length [66,80].  The shiny dark green, alternate leaves are
thick and leathery [24,45,80].

Small, urn-shaped flowers are borne in showy clusters on terminal and
subterminal bracteate racemes [42,45,66,80].  The white, pink or
deep-rose tinged flowers are sticky and glandular [80,98].  Floral
morphology has been examined in detail [19].  Fruit is a round, reddish,
purplish, or bluish black "pseudoberry" or capsule which is made up of a
fleshy outer calyx [45].  Fruits are covered with tiny hairs [42] and
average 0.24 to 0.4 inch (6-10 mm) in diameter [66].  Each fruit
contains an average of 126 brown, reticulate seeds approximately 0.04
inch (1 mm) in length [45,98].

Salal leaves generally live for 2 to 4 years [45].  Twigs survive for 16
years or longer, but bear leaves only during the first few years [45].
Rhizomatous portions of individual plants can live for hundreds of years
[102].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Salal is capable of reproduction from seed and vegetative regeneration.
However, seedling establishment is apparently insignificant where plants
are already established.  Additional expansion of existing clones occurs
through layering, sprouting of rhizomes, root suckering, and sprouting
from the stem base [45].

Seed:  Good seed crops are produced regularly, except under a dense
forest canopy where little or no seed is produced [45].  In a British
Columbia study, only 8.7 percent of all twigs produced flowers, and no
flowers were noted where the canopy cover exceeded 33 percent.
Flowering beneath a forest canopy was limited to shoots more than 4
years of age.  Plants that flowered were, on the average, larger and
more vigorous than those that did not.  Flowering characteristics were
documented as follows [15]:

                  age of shoot (years)
                        < or = 4       5        6        7        8     
flowering/total
      shoots                0/13      5/37     8/53     2/7       3/10
      new twigs             0/15     20/139   13/200   14/81     16/288
length of flowering 
      twig (cm)             ----      9.1     7.3      6.6       5.5
# of flowers per twig       ----      6.6     6.6      5.9       5.5
                  
Salal flowers are pollinated by insects such as bees and flies [45].
Seeds are dispersed by a variety of birds and mammals [45,118].
Evidence suggests that seeds consumed by bears may germinate more
readily than uneaten seeds [102].

Germination:  Germination of salal is generally good under laboratory
conditions, with up to 73 percent of the seed eventually germinating
[28,80].  In other laboratory tests, average germination of 27 to 35
percent has been reported [45].  Stratification is not essential for
germination [95], but periods of light (at least 8 hours per day), are
[28].  In laboratory tests, seeds typically begin germinating within 27
[95] or 30 to 45 days [129].  Viability in storage appears limited
[106].  Germination capacity declined from 31 to 21 percent after 1 year
in storage at 40 degrees F (4 degrees C) but averaged 73 and 27 percent
after 3 years in storage at 40 degrees F (4 degrees C) and room
temperature, respectively [28].

Seedling establishment:  Potential for reproduction from seed appears
poor under natural conditions [47,102].  Few seedlings establish despite
the large numbers that germinate.  Seedling establishment may be limited
to favorable microsites or to periods of unusual weather conditions
[102].  Initial seedling growth is slow [45].  Seedlings may require 2
to 3 years to reach 3 to 5 inches (8-13 cm) in height [80].  Early
seedling growth is favored by moist, acidic conditions and partial shade
[28].

Seed banking:  Seed remains viable for several years when properly
stored, but viability is probably much lower under natural conditions
[45].  Kellman [74] sampled soil and litter from beneath 100-year old
Douglas-fir-western hemlock stands in coastal British Columbia.  Core
samples were divided into an upper layer, 0 to 2 inches (0-5 cm), and
lower layer, 2 to 4 inches (5-10 cm).  Although seed was found in only 1
out of 34 cores, subsequent establishment did occur in laboratory tests
[74].  Seed banking, although possible, is presumably a relatively
unimportant regenerative strategy in salal.

Vegetative regeneration:  Salal sprouts prolifically from roots,
rhizomes, underground stems, and the stem base after disturbances which
damage or remove aboveground plant parts [80,102,106,121], and expands
through spreading roots and rhizomes in the absence of disturbance
[24,102,106].  Layering, rooting at the stem nodes, and spread through
stolons has also been reported [24,28].  Stems which are forced into the
organic mat typically generate adventitious roots.  Salal plants are
often made up of several individual aboveground shoots connected
belowground by several meters of rhizomes [15].

Vegetative regeneration occurs under either a sparse or dense overstory
canopy, and where canopy cover exceeds 33 percent, represents the only
mode of regeneration.  Plants growing beneath a sparse overstory
produced an average of 0.21 shoots per plant per year while those
beneath a closed canopy generated 11 new shoots per plant per year.
However, shoots typically live longer (10.33 years) beneath a sparse
overstory canopy than beneath a closed canopy (6.25 years).  As the
overstory canopy becomes more dense, investment in rhizome extension
increases.  This expansion could represent an "escape from shading"
under conditions of changing canopy gaps.  Bunnell notes that "under
canopy, the spatial pattern of...shoots was better adapted to maintain
plant persistence than to colonize new areas" [15].  Messier and others
report that plants allocate greater energy to the rhizomes as they
mature [92].  Bunnell observed that vegetative regeneration typically
declines with increasing age (> 3 years) [15].  No new shoots were
produced by plants 9 years or older.  Early sprout growth may be slow.
Plants may need as long as 5 years to regenerate stems and produce
aboveground growth [80].


SITE CHARACTERISTICS : 
Salal grows in warm, moist to dry, montane to lowland coastal conifer
forests of the Pacific Northwest [50,66].  It occurs in a variety of
communities including marginal peatland forests, soligenous fens,
forested swamps, bogs, and muskegs [39,99,125].  In parts of British
Columbia, it occurs in shrub communities at the driest edges of bogs
[59,132].  Salal is tolerant of salt spray and commonly forms dense
stands in northern coastal shrub communities [50,58].  It grows well on
stabilized dunes, exposed slopes, rocky bluffs, and knolls near the
ocean [37,45].  It is a common component of swampy shore pine or spruce
woodlands [37,126].  Salal commonly grows vigorously after stands are
opened by timber harvest and persists in many coastal brushfields.
Salal grows well in partial shade, although vigor may be poor beneath a
dense canopy [45].  This shrub persists in sun or shade [138].  Salal
commonly forms dense thickets beneath the forest canopy and at forest
margins [80].  In pygmy forests dominated by bishop pine (Pinus
muricata), lodgepole pine, and cypress (Cupressus pygmaea), it grows as
a dwarf, spreading shrub [126,137].

Salal typically occurs on moderately warm dry sites in western hemlock
communities [26,51,79] and on very dry to wet sites in coastal
Douglas-fir communities [100].  Salal grows on warm, dry sites with
Pacific silver fir [60] and on drier sites in Port-Orford-cedar and
tanoak communities [5,6].  It grows as an understory dominant in coastal
coniferous forests [45] commonly dominated by western hemlock, western
redcedar, Port-Orford cedar, Sitka spruce, lodgepole pine, and Alaska
cedar (Chamaecyparis nootkatensis) [39,46,130,138].  Salal is also
common in mixed evergreen, redwood (Sequoia sempervirens), and subboreal
spruce communities, and in pygmy forests of northern California
[52,98,114,126,137].

Plant associates:  Salal commonly occurs with species such as red alder
(Alnus rubra), salmonberry (Rubus spectabilis), vine maple, western
swordfern, rhododendron, vaccinium (Vaccinium spp.), dwarf Oregon grape,
Pacific dogwood (Cornus nuttallii), tanoak, threeleaf foamflower, and
deerfern in western hemlock or western hemlock-western redcedar forests
[8,51,56,63].  Vine maple, oceanspray, dwarf Oregon grape, Pacific
rhododendron (Rhododendron macrophyllum), and California hazel are
common associates in Douglas-fir forests [3,44,48].  The understory may
be depauperate in old growth stands.  In redwood forests, salal grows
with dwarf Oregon grape, evergreen huckleberry, willow (Salix spp.),
California hazel, Pacific madrone (Arbutus menziesii), California laurel
(Umbellularia californica), and rhododendron [113,126].  In northern
coastal scrub, chaparral broom (Baccharis pilularis), many-colored
lupine (Lupinus varicolor), trailing blackberry, pearly everlasting,
common velvetgrass (Holcus lanatus), and California oatgrass (Danthonia
californica) are common associates [58].

Soil:  Salal grows on a variety of mineral and organic substrates
including shallow rocky soils, sand dunes, coarse alluvium, glacial
till, and peat [45,56].  Growth is generally best on moist sandy or
peaty soils where salal occurs as a vigorous upright shrub [45].  Salal
grows on nutrient poor to moderately rich soils [45,79].  On shallow,
droughty soils, plants may assume a matlike growth form.  Salal commonly
grows on decaying wood and stumps and can grow as an epiphyte on living
trees in extremely humid areas [45].  It occurs on soils derived from a
wide range of parent material including diorite, breccia and basalt,
serpentine, granite, and metamorphic rock [51,114,138,139].

Climate:  This shrub grows in hypermaritime to maritime zones
characterized by cool, humid to perhumid, mesothermal climate [78,79].
Winters are typically mild with little snow accumulation [45].  Plants
are dwarfed in drier areas [138].  Salal reaches greatest size and
abundance in the fogbelt along the Pacific Coast [129].  Plants are
sensitive to frost [45].

Elevation:  Salal typically grows at low to intermediate elevations.
Elevation by geographic location is as follows [45,98]:

                  > 2,500 feet (> 763 m) in CA
                  0 to 2,624 feet (0-800 m) in s coastal BC
                  < 33 to 116 feet (<100-200 m) in n coastal BC


SUCCESSIONAL STATUS : 
Salal is a residual species which persists on many types of newly
disturbed sites [31,36,47,71].  It can rapidly colonize open areas,
particularly on undisturbed soil [15,31] and appears well adapted for
"opportunistic survival in ...changing canopy gaps" [15].  Salal
commonly increases in abundance and cover on clearcuts in old growth
western hemlock and western hemlock-western redcedar forests of the
Northwest [136].  Typically, it is initially much reduced by logging and
postharvest fires but recovers dramatically [47].  Salal is a common
constituent of persistent seral brushfields and can remain dominant for
25 years [36] or more.  The shrub was observed on mudflow channels,
buried roadbanks, blowdown, and scorch sites soon after the eruption of
Mount St. Helens [49,91].

Douglas-fir-western hemlock: Salal grows in early seral to climax stands
in Douglas-fir-western hemlock forests and in coastal western hemlock
forests of the Northwest [42,55,56,78].  Weedy invaders such as
groundsel (Senecio spp.), fireweed (Epilobium angustifolium), pearly
everlasting (Anaphalis margaritacea), and bracken fern are common
dominants during the first three growing seasons after fire or other
disturbances [61,82,84].  Subsequent recovery of salal is commonly rapid
[8] with this shrub assuming prominence within 3 to 5 years after
disturbance [39,122].  According to Bunnell, 85 percent of the space
that will be occupied by salal is occupied within 3 years [15].  By year
8, salal can fully occupy the belowground environment [143] and
continues to increase as fireweed declines [8].  By the 10th growing
season, salal may reach 2 to 3 feet in height [112].  In western
Washington, salal commonly increases in density as second growth
conifers begin to overtop the shrub layer [14].  Salal commonly shares
dominance with dwarf Oregon grape during postdisturbance years 7 to 50
in the Oregon Coast Range [8].

Salal is a principal understory species in many Douglas-fir forests of
the Olympic Mountains where it dominates 65- to 90-year-old and
300-year-old stands [34].  It is common in second growth Douglas-fir
stands of the Oregon Coast Range [8] and northeastern Olympic Mountains
of western Washington [105], but in some areas, it may be sporadic or
absent in the shaded understory of immature, closed canopy stands [79].
Salal can attain temporary dominance approximately 22 years after
disturbance [84].  Salal commonly attains peak abundance in middle-late
to late seral stages following fire [47].  As the overstory develops
further, cover gradually declines [84].  Cover of salal by stand age has
been documented as follows in western Washington [84]:

            stand age (years)
            (percent ground cover) -

      5      22     30      42      73

   12.22   65.26   44.56   43.72   30.90

Cover was documented as follows in a Douglas-fir-western hemlock forest
of western Cascades of Oregon [115]:

                              years (percent cover)

       2     5     10     15     20     30     40    undist. old growth

     7.37   1.41   10   8.52   9.93   17.74  14.97         7.37

Salal commonly persists as an understory dominant or codominant in
relatively dry Douglas-fir forests of British Columbia [79] and the
Pacific Northwest [5].  However, many moist northwestern Douglas-fir
forests are seral to western hemlock types, and with time, the
composition of the overstory gradually shifts from Douglas-fir to
hemlock or cedar-hemlock [39].  True climax status may not be reached
for several hundred years [84].  In climax stands, the herbaceous layer
is often depauperate [8].  Salal and dwarf Oregon grape are often the
only two species with more than 1 percent cover [8].  Salal is a common
understory dominant in climax western hemlock-western redcedar forests
[8] and in coastal western hemlock forests [78] but may be absent in
mature western redcedar forests of coastal British Columbia [79].

Port-Orford-cedar:  Salal occurs in seral to climax stands in
Port-Orford cedar communities [5].  It occurs as an understory dominant
in drier Port-Orford-cedar forests of the Siskiyou Mountains [6].

Redwood, Sitka spruce:  Salal commonly increases after logging in
redwood [11] and Sitka spruce [2] forests.


SEASONAL DEVELOPMENT : 
Salal exhibits variable annual and geographic phenological development.
In a Washington study, bud burst occurred in April, with rapid
vegetative growth occurring from April until early June when growth
peaked [45].

Plants generally flower in late spring or early summer [80] with fruit
ripening from August through October [28,45].  Fruit may persist on the
stem until December [45,138].  Generalized flowering and fruiting dates
by geographic location are as follows:

location          flowering        fruiting          authority

AK                May-June         ----              [130]
BC                June 12-July 4   June-September    [45,83]  
CA                March-July       ----              [113]
w WA              ----             3rd week of June  [45] 
w OR, sw WA       May-July         ----              [50]
Northwest         May-July         ----              [67]      

Related categories for Species: Gaultheria shallon | Salal