BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Artemisia californica | California Sagebrush 



GENERAL BOTANICAL CHARACTERISTICS : 
California sagebrush is a native subshrub with multiple stems arising
from the root crown.  It grows from 2 to 5 feet (0.6-1.5 m) in height
[11,25,62,63].  The lower branches are woody and usually do not exceed
0.2 inch (50 mm) in diameter.  Ring counts of large lower branches show
ages of 15 to 25 years [50].  Leaves are seasonally dimorphic.  Slightly
larger leaves attached to main branches or stems appear early.  Most of
these leaves remain on the stem through the dry season, although they
may wilt [19,20,85,93].  Side-shoots develop from the leaf axils of
larger leaves on lower branches.  These side-shoots develop smaller,
persistent leaves [20,21].  The smaller leaves can remain wilted for
long periods of time under water stress and rehydrate within hours of
rainfall [85,93].  Both types of leaves are highly aromatic due to the
presence of terpenes [34,87].  The inflorescense is a dense panicle
[63].  The fruit is a small achene with a minute pappus [41].  Roots are
shallow [54].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  The light seeds of California sagebrush are wind dispersed and
may travel for long distances before addition to the seedbank [56].
Burkhart [7] reported the seeds as nondormant.  Keeley [41], however,
found that under laboratory conditions, seeds buried near the soil
surface readily germinated in moist soil without special treatment, but
that seeds buried below the level of light penetration failed to
germinate until exposed to charred wood leachate.  California sagebrush
is rated as moderate to high in rate of seed germination during
fire-free intervals [90].  Because of steady germination of soil-stored
seeds, California sagebrush often fails to develop a seedbank adequate
for recruitment of large numbers of seedlings during the first
postdisturbance growing season [41].  Seedling density usually increases
after growth and flowering of young plants.  Seedling establishment is
poor in mature coastal sage scrub communities; mature California
sagebrush may allelopathically inhibit growth of its seedlings [61].

Vegetative:  California sagebrush sprouts from the root crown following
damage to aboveground portions of the plant unless adventitious buds of
the root crown have been damaged by heat [41,86].  Shrubs often develop
adventitious roots where basal portions of stems are covered with soil
[47].


SITE CHARACTERISTICS : 
California sagebrush attains greatest development on the coastal side of
mountains [31].  In the outer Coast Ranges, it generally occupies
low-elevation sites (< 2,000 feet [610 m]) beneath chaparral
[19,44,42,85].  It may, however, occupy higher elevations where soils
are shallow [42].  Outer Coast Range populations typically occur on all
aspects [50].  Inner Coast Range populations occur on shallow or
droughty soils within a narrow margin between chaparral and desert or
chaparral and semiarid annual grassland.  Aspect is usually south or
west [72].  Channel Island populations are typically found on south or
east-facing slopes with shallow soil [57].  California sagebrush
tolerates a wide range in degree of slope, but slopes are most
frequently steep [45].  It does not occur at elevations above 2,500 feet
(762 m) [62].

Soil textures supporting California sagebrush include sand, sandy loam,
clay, and gravelly clay-loam [14,45,82].  It also grows in
unconsolidated soils that occur in gravel washes, tallus slopes, and
colluvial deposits [13,32,38].  Soil parent materials include granite,
andesite, shale, sandstone, and mudstone [45,50,82].

Climate is generally Mediterranean with a strong maritime influence
[13].  The climate of insular populations is maritime [69].  Ninety
percent of annual precipitation falls between November and April.
Climatic stations in coastal sage scrub receive between 1 to 18 inches
(250-450 mm) of precipitation per annum [45].  Northeasterly Santa Ana
foehn winds occur in the Transverse Ranges from mid-fall to December and
prevailing westerly winds are common in spring, summer, and early fall [43].


SUCCESSIONAL STATUS : 
Facultative Seral Species

California sagebrush is a pioneer in primary and secondary succession
and persists as a dominant species through climax in coast sage scrub
communities [8,32,90].  Its persistence in other communities varies from
early to late seral stages, but California sagebrush is rare in climax
communities other than coastal sage scrub [20,30].

Various successional progressions have been suggested for lower
elevation regions of southwestern California.  The community boundaries
are dynamic, with successional patterns influenced by intervals between
fire or other disturbance, the relative success of different species at
establishing seed in the seedbank, and competitive interactions
following disturbance [20].  Hanes [31] suggests that California
sagebrush and other coastal sage scrub species invade chaparral after
fire or other disturbance but are gradually replaced by chaparral
species in the absence of disturbance.  Keeley and Keeley [42] also
support this hypothesis, stating that frequent disturbance of coastal
sage scrub results in further successional regression to annual
grassland.  Horton [37], however, has suggested that coastal sage scrub
is replaced by coast live oak in the absence of disturbance.
Investigations of postfire succession in the Santa Monica and San
Gabriel mountains showed that California sagebrush readily established
in burned areas previously occupied by either coastal sage scrub or
chaparral, but was eventually outcompeted by chamise or bigpod ceanothus
in areas previously occupied by chaparral [20,30].


SEASONAL DEVELOPMENT : 
Stem growth is initiated in winter.  New leaf growth begins in February,
and leaf production is continuous until late summer.  Old leaves are
shed after 30 to 50 days.  Side-shoots of lower branches begin growth in
May.  The period of maximum stem elongation begins in March and ends in
summer, when drought dormancy begins.  Die-back of upper stems occurs in
late summer or early fall under water stress [19,20,21].  Various times
of flowering have been reported, including periods from August through
December [62], November thorough mid-May [59], and year-round [11].

Related categories for Species: Artemisia californica | California Sagebrush