BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus kelloggii | California Black Oak 



GENERAL BOTANICAL CHARACTERISTICS : 
California black oak is a native, deciduous tree, typically growing from
30 to 80 feet (9-25 m) in height and from 1 to 4.5 feet (0.3-1.4 m) in
d.b.h.  Large trees may exceed 120 feet (36 m) in height and 5 feet (1.6
m) d.b.h.  The species also grows in scrub form on poor sites [7].  In
open areas the crown is broad and rounded, with lower branches nearly
touching the ground or forming a browse line.  In closed stands, the
crown is narrow and slender in young trees and irregularly broad in old
trees.  Trunks are usually free of branches for 20 to 40 feet (6-12 m)
in closed stands.  Trunks are often forked, and usually decayed and
hollow in older trees [34].  The bark is thin and smooth in young trees,
becoming moderately thick, deeply fissured, and platy with age.  This
oak grows from one to several vertical roots which penetrate to bedrock,
with large, laterally spreading roots extending off from vertical ones.
It also has a number of surface roots [7].  Acorns are relatively large
in this species, from 1 to 1.2 inches (2.5-3 cm) long and 0.6 to 0.7
inch (1.5-1.8 cm) wide.  The deeply lobed leaves are typically 4 to 8
inches (10-20 cm) long [31].  California black oak can live up to 500
years of age [7].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  California black oak is wind pollinated.  Trees sporadically
produce acorns beginning at 30 years of age, with large quantities
produced beginning at 80 to 100 years of age [7].  Mast size varies each
year.  A study in Carmel Valley, California, showed that 55 percent of
trees produced no acorns, while 28 percent produced bumper crops [9].
Average production for a 150- to 200-year-old tree is 6,500 acorns [7].
This species apparently produces some acorns that require overwinter
stratification and others that are capable of immediate germination
[41].  Acorns are disseminated by gravity or animals [7].  Establishment
requires a bare mineral or light duff seedbed [22].  Acorn viability
varies greatly.  In the San Bernadino National Forest of California,
percent germination ranged from 20 to 93, depending upon the parent tree
and moisture content of the acorn [20].  Generally, acorns with higher
moisture contents show poor emergence; acorns of this species are highly
susceptible to fungi.  Animals also greatly influence seedling
recruitment.  Insects destroy many acorns, and many others are consumed
by rodents, black-tailed deer, and livestock [7].  In a study area in
the Cuyamaca Mountains, deer consumed 85 percent of one season's mast.
The following spring, deer consumed 100 percent of emerging seedlings.
As a result of acorn and seedling predation, there has been almost no
seedling recruitment in the area for the past 25 years [6].

Germination is hypogeal.  Acorn germination and subsequent seedling
establishment rates are best in acorns buried by seed-caching rodents or
birds.  The California ground squirrel and the Stellar's jay are of
greatest importance as California black oak acorn cachers.  Seedlings
cannot establish on heavy clay soils or soils compacted by logging.
Besides previously mentioned deer, other animals adversely affecting
seedling establishment include pocket gopher, lagomorphs, grasshoppers,
and other insects.  Young seedlings are often killed by drought.  Shoot
and horizontal root development are slow for the first 6 to 7 years,
with most initial growth concentrated on vertical roots.  Seedlings do
not compete well against conifer seedlings but will grow through
chaparral brush [7].

Vegetative:  California black oak sprouts vigorously from the stump or
root crown after being cut or burned [7].


SITE CHARACTERISTICS : 
California black oak grows on well-drained soil derived from diverse
parent materials.  It is rarely found, however, on serpentine soil.
Soil textures range from sandy loams to gravelly-clay loams.  Best
growth is attained on deep, slightly acid loam.  In Oregon, the
elevational range is from 450 to 1,000 feet (137-305 m).  In California,
it varies from 200 to 8,000 feet (60-2,440 m) [7].  The climate is
mediterranean, characterized by wet, mild winters and hot, dry summers.
Eighty to ninety percent of the annual precipitation falls from November
to April [30].

Associated species:  Common overstory associates of California black oak
not listed as SAF cover types include incense-cedar, tanoak (Lithocarpus
densiflora), interior live oak, Pacific dogwood (Cornus nuttallii), and
bigleaf maple (Acer macrophyllum) [7].

Shrub associates include over 30 species.  Some of the most common are
greenleaf manzanita (Arctostaphylos patula), whiteleaf manzanita (A.
viscida), deerbrush (Ceanothus integerrimus), Brewer oak (Q. garryana
var.  breweri), Sierra gooseberry (Ribes roezlii), poison-oak
(Toxicodendron diversilobum), and Sierra mountain misery (Chamaebatia
foliolosa) [7].


SUCCESSIONAL STATUS : 
This tree is moderately shade tolerant in early life, growing best in
full sun but persisting in dense shade.  Pole-sized California black oak
is less shade tolerant, growing tall and thin until reaching a position
in the canopy where light is received.  Older trees are shade intolerant
[7].  

The successional status of this species is unclear.  Cooper [10] has
suggested it is a climax species, representing a forest type
transitional between chaparral and coniferous forest.  McDonald [15]
states that it is a persistant subclimax species, with frequent fire or
logging activities maintaining its dominance.  According McDonald,
California black oak is slowly replaced (40+ years) by conifers in the
absence of disturbance.


SEASONAL DEVELOPMENT : 
The following seasonal development has been reported for this species [7]:

     catkins mature:  mid-March to mid-May
     leaf drop:  mid-August to mid-September
     acorns mature:  mid-August to mid-September of second year
     acorns drop:  mid-August to early November of second year

Related categories for Species: Quercus kelloggii | California Black Oak