Index of Species Information
SPECIES: Quercus phellos
Introductory
SPECIES: Quercus phellos
AUTHORSHIP AND CITATION :
Carey, Jennifer H. 1992. Quercus phellos. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service,
Rocky Mountain Research Station, Fire Sciences Laboratory (Producer).
Available: http://www.fs.fed.us/database/feis/ [].
ABBREVIATION :
QUEPHE
SYNONYMS :
NO-ENTRY
SCS PLANT CODE :
QUPH
COMMON NAMES :
willow oak
peach oak
pin oak
swamp willow oak
TAXONOMY :
The currently accepted scientific name of willow oak is Quercus phellos
L. [21,30]. It has been placed within the subgenus Erythrobalanus or
black (red) oak group. There are no recognized varieties, subspecies, or
forms. Willow oak hybridizes with the following species [21,30]:
x Q. velutina (black oak): Q. X. filialis Little
x Q. falcata (southern red oak): Q. X. ludoviciana Sarg.
x Q. ilicifolia (bear oak): Q. X. giffordii Trel.
x Q. marilandica (blackjack oak): Q. X. rudkinii Britton
x Q. nigra (water oak): Q. X. capesii W. Wolf
x Q. palustris (pin oak): Q. X. schociana Dieck
x Q. rubra (northern red oak): Q. X. heterophylla Michx. f.
x Q. shumardii (Shumard oak): Q. X. moultonensis Ashe
x Q. incana (bluejack oak)
LIFE FORM :
Tree
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
DISTRIBUTION AND OCCURRENCE
SPECIES: Quercus phellos
GENERAL DISTRIBUTION :
Willow oak occurs on the Atlantic and Gulf coastal plains from New
Jersey and southeastern Pennsylvania to Georgia and northern Florida;
west to east Texas; and north in the Mississippi River valley to
southeastern Oklahoma, Arkansas, southeastern Missouri, southern
Illinois, western and southern Kentucky, and eastern Tennessee. Willow
oak is absent from peninsular Florida and southeastern Georgia [21,30].
ECOSYSTEMS :
FRES13 Loblolly - shortleaf pine
FRES14 Oak - pine
FRES16 Oak - gum - cypress
STATES :
AL AR DE FL GA IL KY LA MD MO
MS NC NJ NY OK PA SC TN TX VA
BLM PHYSIOGRAPHIC REGIONS :
NO-ENTRY
KUCHLER PLANT ASSOCIATIONS :
K111 Oak - hickory - pine forest
K112 Southern mixed forest
K113 Southern floodplain forest
SAF COVER TYPES :
65 Pin oak - sweetgum
80 Loblolly pine - shortleaf pine
81 Loblolly pine
82 Loblolly pine - hardwood
87 Sweet gum - yellow-poplar
88 Willow oak - water oak - diamondleaf oak
91 Swamp chestnut oak - cherrybark oak
92 Sweetgum - willow oak
93 Sugarberry - American elm - green ash
96 Overcup oak - water hickory
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
HABITAT TYPES AND PLANT COMMUNITIES :
Willow oak is commonly found in transitional communities between swamps
and upland mesic forests [1,28]. The willow oak-water oak-laurel oak
(Q. laurifolia) forest cover type is located topographically between the
swamp chestnut oak (Q. michauxii)-cherrybark oak (Q. falcata var.
pagodifolia) type on the higher, better drained sites and the overcup
oak (Q. lyrata)-water hickory (Carya aquatica) type on the lower, more
poorly drained sites. Within the willow oak-water oak-laurel oak type,
willow oak is generally located between laurel oak on the more poorly
drained sites and water oak on the better drained sites [10]. The
following published classifications list laurel oak as a dominant
species:
Southern swamps and marshes [28]
Forest vegetation of the Big Thicket, southeast Texas [23]
Eastern deciduous forest [38]
The natural communities of South Carolina [25]
MANAGEMENT CONSIDERATIONS
SPECIES: Quercus phellos
WOOD PRODUCTS VALUE :
Willow oak is an important source of lumber and pulp. It has good pulp
characteristics and can be harvested when quite young [30].
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
The consistent and abundant acorn crops of willow oak are an important
food source for wildlife including waterfowl, wild turkey, blue jays,
red-headed and red-bellied woodpeckers, flickers, grackles, white-tailed
deer, fox and gray squirrels, and other small rodents [7,30,34]. It
produces a large acorn crop almost every year. Acorns of the black oak
group are an especially important food source in the winter because
those of the white oak group germinate soon after falling and,
therefore, are unavailable [32].
PALATABILITY :
Among 12 southeastern oak species, willow oak acorns ranked fifth in
preference to the fox squirrel [27]. In another study [32], fox
squirrels did not readily eat willow oak acorns, presumably because of
their high tannin content.
Willow oak is considered good browse for white-tailed deer [33].
NUTRITIONAL VALUE :
Willow oak acorns have 5.9 percent total protein and 19.6 percent crude
fat [2]. They are low in phosphorus [2,32,33].
COVER VALUE :
NO-ENTRY
VALUE FOR REHABILITATION OF DISTURBED SITES :
Willow oak is used for restoration of the wetter sites of bottomland
hardwood forests and for rehabilitation of disturbed areas. It is also
a good species to plant along margins of fluctuating-level reservoirs
[30]. Willow oak seedlings planted on canal-excavated material along
the Tennessee-Tombigbee Waterway had high survival (greater than 50
percent) and a mean height growth of 87.2 inches (221.5 cm) in 5 years
[12]. Acorn collection, storage, and treatment methods are detailed
[2,26].
OTHER USES AND VALUES :
This species is used widely as a shade tree and ornamental. It
transplants easily [30].
OTHER MANAGEMENT CONSIDERATIONS :
Willow oak is a preferred timber and wildlife species. It has been
managed for pulp in plantations. Intensive control of competition is
thought to be necessary for willow oak regeneration because of
relatively slow early growth [16], but a recent study [41] showed that
control with a broad spectrum herbicide prior to direct seeding did not
improve survival or height growth of willow oak. In the same study, a
fertilizer tablet placed near the seed of the direct-seeded willow oak
also did not improve survival or growth. General costs and
recommendations for direct seeding of oaks are detailed [3].
Hardwood competition in pine plantations is often controlled by
herbicide. Spring applications of Velpar L work well on willow oak, as
do late summer applications of Roundup [31].
Trunk borers, including red oak borer (Enaphalodes rufulus),
carpenterworm (Prionoxystus robiniae), and living-beech borer (Goes
pulverulentus), are serious insect pests of willow oak that degrade
sawlog quality. Weevils (Curculio spp.) attack acorns. A common butt
rot canker caused by the fungus Polyporus hispidus spreads 4 to 6 inches
(10-15 cm) per year. Infected trees should be removed to salvage the
wood and prevent infection of other trees [30].
Willow oak is susceptible to acid rain. Leaves show yellow or brown
necrotic zones when exposed to simulated rain less than 3.2 pH [30].
In order to provide habitat and food for wintering waterfowl, bottomland
forests, composed of willow oak and other water-tolerant, mast-producing
species, are often impounded during the winter. The shallow water is
drawn down in the early spring to prevent tree damage [24].
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus phellos
GENERAL BOTANICAL CHARACTERISTICS :
Willow oak is a large, deciduous, graceful tree with a straight, tall,
slender trunk and willowlike leaves. The leaves are 5 to 8 times as
long as wide, with no lobes or undulations. This species is long-lived
and shows moderately rapid growth on good sites. It reaches 80 to 120
feet (24-37 m) in height and 40 or more inches (100+ cm) in d.b.h. On
alluvial soils, the feeder roots are concentrated in the aerated layer
above the saturated zone. Roots do not penetrate the zone of
free-standing water [9,30,34].
RAUNKIAER LIFE FORM :
Phanerophyte (mesophanerophyte)
Phanerophyte (megaphanerophyte)
REGENERATION PROCESSES :
Sexual: Willow oak is monoecious. Acorn production begins when the
tree is about 20 years old. This species produces a good acorn crop
nearly every year. Dissemination is by animals and water [30]. Blue
jays transport and cache acorns up to several kilometers from the
collection tree. Blue jays seem to prefer species with small to
medium-sized acorns, such as willow oak [8].
Germination is hypogeal. The best germination site is moist
well-aerated soil with 1 or more inches (2.5+ cm) of leaf litter [30].
An 8-week submersion in water slightly reduced the germination capacity
of willow oak acorns [20] but not enough to affect the species' ability
to regenerate an area [30].
Early height growth of seedlings is moderate. On good sites, a seedling
will grow 4.5 feet (1.4 m) in 2 years [30]. Total height growth on a
peat swamp forest site was 4.3 feet (1.3 m) after four growing seasons.
On a wet flat (pocosin) forest site, total height growth was 6.7 feet (2
m) after 8 growing seasons [18]. Although moderately intolerant of
shade, seedlings will persist as long as 30 years under a forest canopy
[30].
Moisture must be available during the entire growing season for best
growth. However, complete soil saturation during the growing season
inhibits root growth. Willow oak seedlings averaging 9.8 inches (24.8
cm) in height survived a 60-day period of complete soil saturation, but
height growth was significantly (p < 0.01) reduced and there was some
mortality of secondary roots [14]. Older trees may survive up to 3
years of continuous flooding [13]. However, permanent standing water
kills the root system and eventually the tree [30].
Vegetative: Willow oak sprouts readily from stumps of smaller trees
[30].
SITE CHARACTERISTICS :
Willow oak grows primarily on floodplain sites that are commonly flooded
in the winter and spring, but only briefly during the growing season.
This species usually grows on ridges and high flats of first bottoms
which are the areas surrounding swamps and major rivers which flood
deeply and frequently, but drain rapidly because of relief. It also
grows along minor streams and on ridges, flats, and sloughs of second
bottoms which flood infrequently. It rarely occurs on uplands
[6,30,34].
Willow oak is found in the forests on North Carolina's outer barrier
islands, but it is rarely encountered on South Carolina's outer
barriers [15].
Willow oak grows best in moist alluvial soils that are deep,
uncompacted, and relatively undisturbed. The best soil is
medium-textured, silty or loamy, and has at least 2 percent organic
material and a pH between 4.5 and 5.5. The most common soils are in the
orders Inceptisols and Alfisols [30]. The ideal depth of the water
table during the growing season is 2 to 6 feet (0.6-1.8 m). A water
table less than 1 foot (0.3m) or more than 10 feet (3 m) below the
ground surface is unsuitable for willow oak [30,34].
In addition to those species mentioned in Distribution and Occurrence,
overstory associates include red maple (Acer rubrum), cedar elm (Ulmus
crassifolia), eastern cottonwood (Populus deltoides), honeylocust
(Gleditsia triacanthos), persimmon (Diospyros virginiana), Nuttall oak
(Quercus nuttallii), chestnut oak (Q. prinus), and spruce pine (Pinus
glabra). Shrub and small tree associates include swamp privet
(Forestiera acuminata), roughleaf dogwood (Cornus drummandii), hawthorn
(Crataegus spp.), American hornbeam (Carpinus caroliniana), and red
mulberry (Morus rubra). Vines include Alabama supplejack(Berchemia
scandens), greenbrier (Smilax spp.), poison-ivy (Rhus radicans),
peppervine (Ampelopsis arborea), trumpet-creeper (Campsis radicans),
crossvine (Anisostichus capriolata), and grape (Vitis spp.) [7,10,25,30].
SUCCESSIONAL STATUS :
Facultative Seral Species
Willow oak is shade intolerant and responds well to release [30].
The willow oak-water oak-laurel oak forest cover type may represent a
topographic or edaphic climax on terrace flats and poorly drained
flatwoods. These stands, known as "pin oak flats" with very little
vegetation growing beneath the oaks and water standing much of the year,
may be entirely willow oak. True pin oak (Q. palustris) is found on
similar sites in the northern latitudes of the southern hardwood region
[10].
In the absence of fire, willow oak and laurel oak will expand into
wetland savannas in the Big Thicket area of east Texas and become a "pin
oak flat" [40].
SEASONAL DEVELOPMENT :
Flowering takes place between February and May, usually a week before
the leaf buds open. Acorns mature between August and October of their
second year. Seeds germinate the spring after seedfall [30].
FIRE ECOLOGY
SPECIES: Quercus phellos
FIRE ECOLOGY OR ADAPTATIONS :
Willow oak is fire intolerant because of thin bark [30]. Fire is
generally infrequent in willow oak habitats because the proximity to
water discourages fire entry [5]. Willow oak leaves and other fuels
along waterways are often moist and do not burn well [33].
POSTFIRE REGENERATION STRATEGY :
Tree with adventitious-bud root crown/root sucker
Secondary colonizer - off-site seed
FIRE EFFECTS
SPECIES: Quercus phellos
IMMEDIATE FIRE EFFECT ON PLANT :
Willow oak is easily damaged by fire. Seedlings and saplings are
usually top-killed by low-severity fire. Large trees are top-killed by
high-severity fire [30]. In a study on the Santee Experimental Forest
in South Carolina, periodic winter and summer low-severity fires and
annual winter and summer low-severity fires were effective at reducing
the number of hardwood stems (including willow oak) between 1 and 5
inches (2.6-12.5 cm) in d.b.h. Annual summer fires also reduced the
number of stems less than 1 inch (2.5 cm) in d.b.h. Root systems were
weakened and eventually killed by burning during the growing season [39].
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
NO-ENTRY
PLANT RESPONSE TO FIRE :
Young willow oak sprouts readily from the root collar if top-killed by
fire. Older trees do not sprout as readily [30].
Fire may severely wound surviving trees. The tree may appear normal
immediately following the fire except for discolored bark, but cracks in
the bark develop after 1 year. Insects and fungi attack the tree and
the bark sloughs off in about 2 years [35]. The average rate of spread
of fungal rot in fire-scarred willow oak is 1.25 feet (0.4 m) per decade
[36].
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS :
Hardwoods growing within a pine forest are often controlled with
prescribed fire. Oaks up to 3 inches (7.6 cm) in d.b.h. are usually
top-killed and sprouts kept small and controllable with prescribed
winter fires. Summer fires are also effective, but are more detrimental
to the wildlife food supply [4]. If willow oak is being grown
commercially, protection from fire is highly desirable [35].
Because willow oak leaves and habitat are often moist, fuels should be
allowed to dry at least 3 weeks following a rain of 0.5 inch (1.3 cm) or
more. Some fires will not carry even under ideal conditions of less
than 4 percent fuel moisture, 20 to 30 percent relative humidity, and 2
mile (3.2 km) per hour winds within the stand. The most effective
prescribed burning is done between late spring and early winter [33].
REFERENCES
SPECIES: Quercus phellos
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