BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus wislizenii | Interior Live Oak 



GENERAL BOTANICAL CHARACTERISTICS : 
Interior live oak is a slow-growing, variable evergreen which grows as a
large shrub or small tree [15,40,61].  Plants may reach 30 to 75 feet
(10-22 m) in height or assume a shrublike growth form with maximum
heights of only 8 to 10 feet (2.4-3.1 m).  D.b.h. generally ranges from
1 to 3 feet (0.3-0.9 m) [47].  A maximum size of 85.3 inches (216.7 cm)
d.b.h. and 90 feet (27.5 m) in height has been reported [10].  The
gray-to-dark gray bark is smooth when young but becomes rough and
broadly ridged at maturity [40,47].  Young twigs are green-to-reddish
but become gray with age [15].  Roots can extend from 30 to 70 feet deep
(10-21 m) [18,54].  Interior live oaks have been aged up to 150 to 200
years, although the root system is often much older [47].

In relatively open stands the crown is usually dense and full, and
foliage often extends to the ground.  However, crowns are often
irregularly shaped in closed stands [47].  Leaves, which persist for 2
years, are mostly oblong-to-elliptic or lanceolate, and spiny-toothed to
entire [40,47].  Both leaf surfaces are shiny green but the upper
surface is darker [15,47].

Interior live oak is monoecious.  Male flowers are borne in catkins 1 to
3 inches (2-5 cm) in length, whereas female flowers grow in clusters of
two to four in the upper leaf axils [15].  The tan, often longitudinally
striped acorns are slender, cylindrical to conical, with a turbinate cap
[40].

The shrubby variety frutescens is characterized by stiff, rigid twigs
and ovate or oblong leaves 0.8 to 1.6 inches (2.0-4.1 cm) in length
[40,56].  Acorns are oblong-to-ovate and the cup is covered with thin
brown scales [56].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Interior live oak regenerates vegetatively after disturbance and also
reproduces through seed.  Both modes of regeneration appear to be
important, although the relative value of each depends on such factors
as weather, seed disseminators, soils, and the type and intensity of
disturbance.

Seed:  Mature acorns of interior live oak are slender, oblong to ovate,
or pointed [15,40,47].  Cleaned acorns average approximately 125 per
pound (275/kg).  Annual seed production appears to be somewhat variable,
although each interior live oak tree generally produces good seed crops
at 5- to 7-year intervals [43].  The dry weight yields of fallen acorns
in interior live oak stands range from 0 to 97 pounds per acre (0-109
kg/ha) [66].  Interior live oak produces an average of 958 pounds per
acre (1,074 kg/ha) of tree canopy in good mast years but averages only
113 pounds per acre (614 kg/ha) in poor mast years [37].

Germination:  Ripening time varies according to annual growing
conditions and elevation [35,46].  Viable acorns have been picked as
early as August 10, although these acorns did not germinate without
prior stratification.  Acorns collected 2 to 4 weeks later germinated
without any additional treatment [46].  Germination is frequently
delayed at higher elevations.  It commonly occurs during late November
through January at lower elevations but often does not take place until
January or February at higher elevations [35].  Research indicates that
the acorns of interior live oak can germinate without exposure to low
temperatures [13,35].  However, exposure to temperatures of 32 to 41
degrees F (0-5 degrees C) can effectively stratify seed and enhance
germination [13,16].  Results of germination tests are as follows [43]:

     cold stratification     temperature F      duration      germination
     (days)                  day      night     (days)        capacity (%)

     30 to 60                86         68         69             75

In laboratory tests, 50 percent of all acorns germinated within 40 days
after exposure to temperatures of 55 to 68 degrees F (13-20 degrees C)
without prior stratification [35].  Acorns are not noted for long
viability.  Some acorns of interior live oak germinate after 6 to 12
months of storage, but many exhibit damage or deformity [46].

Seed dispersal and mortality:  Gravity and animal vectors aid in the
dispersal of interior live oak.  Squirrels and jays appear to be
particularly important dispersal agents, although they consume many
acorns.  Acorns are vulnerable to predation and nearly 100 percent of
the acorns may be consumed where deer, pigs, or bear occur [3].  Acorns
are also susceptible to rot, insects, and disease.  Mortality of planted
interior live oak acorns ranged from 2 to 27 percent under carefully
controlled laboratory experiments [35].

Vegetative regeneration:  Interior live oak sprouts vigorously after
fire or mechanical disturbance [15,22,44].  Root crown sprouting
frequently occurs after damage to the trunk or crown [47].
Stump-sprouting is also common after fire or timber harvest [10,15].
Sprout growth of interior live oak is described as "moderate at best"
[P. McDonald, pers. comm. 1990].


SITE CHARACTERISTICS : 
Interior live oak most commonly grows scattered in valleys, foothills,
or on slopes at low to middle elevations [35,40].  It is often found in
canyon bottoms and dry washes of southern California [48] and on broad
alluvial banks of rivers in the Sierra Nevada [47].

Elevation:  Generalized elevational ranges of interior live oak are as
follows [35,47]:
     
          from 1,000 to 2,000 feet (300-600 m) in northern CA
          up to 6,200 feet (1,300 m) in southern CA
          from 3,950 to 4,950 feet (1,200-1,500 m) in Sierra Nevada, CA
          from 200 to 1,950 feet (60-600 m) in Santa Lucia Mtns., CA

Soils:  California oaks generally grow well on a variety of soils
including well-drained, fine-grained to cobbly or gravelly sandy loams,
or skeletal soils.  Soil pH generally ranges between 5.6 and 7.5, with
common soil depths of 20 to 40 inches (50-100 cm) [48].  Interior live
oak grows particularly well on dry, shallow, well-drained loams, clay
loams, gravelly loams, or gravel [12,27,34,65].


SUCCESSIONAL STATUS : 
Interior live oak is tolerant of shade, particularly when young [47],
and occurs within the understory of some climax conifer forests of
California.  Cooper [17] reported that the variety frutescens is
especially common in climax chaparral communities which are maintained
by fire.  Interior live oak is a prolific sprouter and can also assume
prominence in some early seral communities.


SEASONAL DEVELOPMENT : 
Interior live oak flowers from March to May [40].  Acorns mature in the
second year [12].  Ripening time varies annually and depends largely on
elevation and growing conditions.  Acorns generally ripen after
mid-August [46].  Immature acorns of live oaks which are poorly
developed, or which have been damaged by rain, hail, wind, or insects
may begin to fall as early as May [35].  Mature acorns are dispersed in
late summer or fall.

Related categories for Species: Quercus wislizenii | Interior Live Oak