VALUE AND USE
SPECIES: Quercus lobata | Valley Oak 



WOOD PRODUCTS VALUE : 
Valley oak lumber has a propensity to crack and warp while drying, and
is often stained by fungus.  These problems, however, can be overcome,
and there is a small commercial market for the lumber in the manufacture
of cabinets.  The wood is occasionally used for wine barrels.
Historically, it was primarily used as firewood and as a source of
commercial charcoal.  Valley oak wood was also utilized in the
construction of the steamboats that once ran the Sacramento and San
Joaquin Rivers, and as keel blocks during World War II [34,62,74].


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
Remaining valley oak riparian and woodland areas comprise critical
habitat which is intensively used by wildlife.  Collectively, valley oak
riparian forests support 67 nesting bird species, more than any other
California habitat for which data are available [23].  The
state-threatened Swainson's hawk is closely associated with riparian
habitat in the Central Valley, where these hawks use large valley oaks
as nesting sites [66].  Other animal species living within the valley
oak riparian forest cover type and in danger of extirpation include the
state-threatened greater sandhill crane, the state-endangered
yellow-billed cuckoo, and the federally-threatened elderberry longhorn
beetle [26,40].  In addition, these forests provide habitat for rare
remnant populations of ringtail in the Central Valley [9].  Valley oak
woodlands support much wildlife as well.  The valley oak woodland of the
Tehachipi Mountains supports 45 species of birds.  Valley oaks there are
preferred foraging substrate for the northern oriole, housewren, and
acorn woodpecker [12].  The valley oak woodland of the Bobelaine Audubon
Sanctuary near the Feather River has a mean density of 16 birds per acre
(40 birds/ha), with 35 species present.  The area is preferred wintering
grounds for various sparrows and the dark-eyed junco [51].

Valley oak is used by various cavity-nesting and cavity-storing birds
and mammals [50].  It supplies browse for livestock, black-tailed deer,
lagomorphs, and various rodents.  Pocket gopher, California ground
squirrel, and deer mouse are heavy consumers of valley oak seedlings.
Acorns are an important diet item of the California ground squirrel,
pocket gopher, scrub jay, yellow-billed magpie, acorn woodpecker,
black-tailed deer, feral pig, and of cattle.  Roots are consumed by
feral pig and pocket gopher [30,35,75].


PALATABILITY : 
Valley oak acorns are selectively chosen by acorns predators over those
of other species, probably because of their large size [70].

The palatability of mature valley oak browse has been rated as poor for
cattle; useless for horses; poor to useless for sheep and goats; and
fair to poor for black-tailed deer [63].


NUTRITIONAL VALUE : 
The percent composition of valley oak acorns is as follows [76]:

        moisture        40.57           ash          1.08
        crude protein    2.82           calcium      0.08
        crude fiber      7.84           phosphorus   0.06
        fat              4.25           tannins      3.85

Information on the nutritional value of valley oak browse is sparse.
The mineral value of mature leaves for black-tailed deer is rated as
follows [67]:

        phosphorus:   fair
        calcium:   good
        phosphorus/calcium ratio:   fair (0.20:0.86)


COVER VALUE : 
NO-ENTRY


VALUE FOR REHABILITATION OF DISTURBED SITES : 
There is great interest among public and private managers to restore as
much valley oak woodland and riparian forest as possible, and
revegetation projects are numerous [25,26,54,56,58].  Due to heavy acorn
and seedling predation, however, mortality of newly-established
populations often approaches 100 percent on project sites [1,30].
Enclosing plants in a protective device such as wire caging is
recommended until tree height exceeds the browse line.  The
effectiveness of various protective devices has been detailed in the
literature [19,33].  Trees are established from nursery stock or from
acorn plantings.  Nursery-grown trees planted in the Sepulveda Wildlife
Reserve of Los Angeles County showed good survival during their first
year [57].  Trees grown from on-site acorn plantings, however, usually
establish a deeper taproot and produce earlier top-growth than
transplanted nursery stock [33].  Irrigating seedlings for the first few
years greatly increases survival and growth rates [19].  The Nature
Conservancy is currently restoring 50 acres (20 ha) of valley oak
woodland on an old field on the Consumnes River Preserve of Sacramento
County.  Seedlings on this project site attained a height of 4 feet (1.2
m) in the first year, and survival was 95 percent in the first 3 years.
Seedlings were protected from aboveground herbivory and watered every 2
weeks during summer.  Grasses and forbs near valley oak seedlings were
weeded [33,34].  In contrast, seedlings at the Hopland Field Station
(Hopland, California), protected from herbivory but left unwatered and
unweeded, attained little or no top-growth in the first year [19].
Fertilizing seedlings is not recommended because it stimulates growth of
competing grass species over growth of the oaks [1].  Acorn collecting
methods and detailed cultivation techniques are described in the
literature [11,19,54,65].


OTHER USES AND VALUES : 
Native Americans used valley oak acorns for making meal [4].  During the
last century, domestic pigs were driven to Central Valley oak woodlands
for mast feedings [61].


MANAGEMENT CONSIDERATIONS : 
The valley oak cover type currently occupies an estimated 274,000 acres
(109,600 ha).  About 86 percent of this is privately owned, and
miscellaneous federal agencies manage most of the land containing the
other 14 percent.  National Forests contain only a trace.  Fifty-two
percent of the valley oak type is in sawtimber stands; 48 percent is in
poletimber and sapling stands [13].  Valley oak cover was once
extensive, extending through lowlands and into foothills [7].  Jepson
[42] reported 400 square miles (91,040 sq km) of valley oak woodland
covering the eastern San Joaquin Valley in 1910.  Valley oak riparian
forest currently occupies about 12,000 acres (4,856 ha) on the
Sacramento River System, approximately 1.5 percent of original acreage
[38].

The greatest problem facing valley oak managers is lack of sapling
recruitment.  Due to a number of factors, most young valley oak die
before reaching sexual maturity [30,61].  Obstacles to sapling
recruitment are discussed in REGENERATION.  Another major management
concern is loss of mature trees.  Valley oak have died in some areas
because of greatly lowered water tables.  In other areas, the
accumulation of saline irrigation runoff has killed oaks.  Mature trees
are sensitive to overwatering, pruning, grade changes, and blankets of
asphalt covering the root system [61].  Trees are resistant to
short-term drought; mature trees suffer drought damage only when a
series of dry seasons lower water tables to extreme dephts [28].

Oak diseases cause scant mortality in valley oak under natural
conditions.  Most valley oaks are infected with the heart-rot fungus
Armillaria mellea, but it is usually fatal to only very old trees.  It
is nearly always fatal, however, to orchard trees planted in fields
recently cleared of oaks [60].  Acorns are frequently infested with
filbert worm (Melissopus latiferreanus) and filbert weevil (Curculio
occidentis).  Fifty-eight percent of insect-infested acorns germinate
and develop normally [43].

Where present, rooting feral pigs cause considerable damage.  In the
valley oak woodland of Pinnacles National Monument, over 9 percent of
total valley oak cover was destroyed by feral pigs.  Managers had the
community fenced off to exclude pigs [35].

Valley oak are not adapted to snow, and the heavy, wet snowfalls that
sometimes occur within their range cause considerable limb breakage
[29].

Related categories for Species: Quercus lobata | Valley Oak