BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus stellata | Post Oak 



GENERAL BOTANICAL CHARACTERISTICS : 
Post oak is a long-lived, native, deciduous tree with a crown of
horizontal branches.  The varieties are distinguished by leaf shape,
acorn size, growth form, and site preferences.  The typical variety
usually grows 50 to 60 feet (15.2-18.3 m) in height and 12 to 24 inches
(30-61 cm) in d.b.h.  It rarely exceeds 100 feet (30.5 m) in height and
48 inches (122 cm) in d.b.h. [47].  In the drier areas of its range
(Texas), post oak is typically only 30 to 40 feet (9-12 m) tall and 15
to 18 inches (38-46 cm) in d.b.h.  Post oak is slow growing and lives
300 to 400 years [24,47].  Seedlings have especially thick taproots.
Most roots develop above underlying clay horizons [47].

Sand post oak is a small, shrubby tree that grows to about 20 feet (6.1
m) in height, but it can be taller.  It sometimes forms thickets from
root suckers [13,46].

Delta post oak is generally larger than the typical variety, growing to
about 100 feet (30 m) in height [13,46].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  Post oak is monoecious.  Seed production begins when the tree
is about 25 years old.  Good crops occur at 2- to 3-year intervals.
Post oak does not produce as many acorns as white oak, blackjack oak,
black oak (Quercus velutina), or scarlet oak (Q. coccinea) [47].

Acorns germinate in autumn soon after falling.  Germination is hypogeal.
The ideal seedbed is moist soil covered with 1 inch (2.5 cm) or more of
leaf litter.  Height and diameter growth are slow; 10 year d.b.h. growth
generally averages less than 2 inches (5 cm).  Post oak usually grows
more slowly than any associated trees except blackjack oak [47].
Average annual height growth of seedlings in Missouri during a 6 year
period was 2.5 inches (6.4 cm) [29].

Seedlings are resistant to drought but not to flooding [47].  Post oak
seedlings were more drought tolerant than white oak, black oak, or
northern red oak (Q. rubra), primarily because of greater drought
tolerance of leaf and root cells [57].

Vegetative:  Trees up to 10 inches (25 cm) in d.b.h. sprout prolifically
from the root crown after being top-killed.  Post oak tends to have
fewer sprouts per clump than black, chestnut, white, or scarlet oaks
[47].  Post oak sprouts grow faster than seedlings [29].  In the Cross
Timbers area of Oklahoma, post oak often occurs in small clusters of two
to six trees.  These clusters may represent a single individual because
the species occasionally reproduces vegetatively from roots, especially
under moisture stress [8].


SITE CHARACTERISTICS : 
Post oak occurs primarily on dry uplands with southerly or westerly
exposures [47] but may occur on terraces of smaller streams in
well-drained soil [23].  Post oak is common to about 2,950 feet (900 m)
in elevation throughout its range and rare to about 4,920 feet (1,500 m)
in the southern Appalachian Mountains [13,47].

The soils are usually shallow, well-drained, coarse-textured, and
deficient in nutrients and organic matter.  It commonly grows in
serpentine soils [56,58].  Post oak is often restricted to sites where a
heavy clay subsurface layer is within 1 foot (0.3 m) of the surface or
bedrock is within 2 to 3 feet (0.6-0.9 m) of the surface [25].  It may
grow in shallow sand overlying beds of clay or gravel, but the typical
variety of post oak appears to be restricted from deep sands [35].  Post
oak grows on drier clayhills that formerly supported longleaf pine
(Pinus palustris) [36].

Post oak occurs on sites too dry for white oak and southern red oak (Q.
falcata) [38], but on slightly more mesic sites than blackjack oak [11]
or eastern redcedar (Juniperus virginiana) [17].  Generally, excessive
soil moisture and inundation cause high mortality or severe stress to
post oak [6]; however, it dominates some flatwoods in southern Indiana
which are moist in the winter [9].

Sand post oak, a common sandhills species, is an obligate inhabitant of
deep sands.  These xeric sands are well-drained, fine, and almost
sterile.  Sand post oak grows to about 820 feet (250 m) in elevation
[12,35,46,47].  It is also found on xeric hammocks [12].

Delta post oak occurs in rich, moist bottomlands, usually on the highest
first bottom ridges and terraces.  Soils are fine, sandy loam [13,47].

In addition to those species mentioned in Distribution and Occurrence,
less common overstory associates of post oak include hickories (Carya
spp.), southern red oak, scarlet oak, bluejack oak, live oak, shingle
oak (Q. imbricaria), chinkapin oak (Q. muehlenbergii), bluejack oak,
Shumard oak (Q. shumardii), blackgum (Nyssa sylvatica), sourwood
(Oxydendron arboreum), red maple (Acer rubrum), winged elm (Ulmus
alata), hackberry (Celtis occidentalis), and dogwood (Cornus spp.) [47].

Overstory associates of Delta post oak include green ash (Fraxinus
pennsylvanica), white ash (F. americana), white oak, water oak,
blackgum, sweetgum (Liquidambar styraciflua), American elm (Ulmus
americana), winged elm, American hornbeam (Carpinus caroliniana),
American sycamore (Platanus occidentalis), black willow (Salix nigra),
and hickories [46,47].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Post oak is intolerant of shade and competition.  Because of slow growth
it is often overtopped by other species, including most oaks.  It
persists and becomes dominant on poor sites because of its drought
resistance [47].  Delta post oak is moderately intolerant of shade [41].

Post oak is common in the understory of pine (Pinus spp.)-hardwood
forests.  In the absence of fire, post oak may become dominant depending
on site conditions and competition from associated species [19].  In an
upland longleaf pine forest in the west Gulf Coastal Plain, post oak,
along with blackjack oak, bluejack oak, and black hickory (Carya
texana), became codominant and eventually replaced longleaf pine [4].

Post oak will expand into adjacent prairies in the absence of fire [47].
The post oak-blackjack oak association may be an edaphic climax on dry
sites [14].

Some of the most xeric sites of the South Carolina Piedmont are occupied
by old-growth communities of post oak, black oak, and blueridge blueberry
(Vaccinium vacillans).  Although the community appears to be in steady
state, it may evolve into a hickory-dominated community in the absence
of fire [25].




SEASONAL DEVELOPMENT : 
Post oak flowers from March to June depending on elevation and latitude.
Flowers appear at the same time as leaves.  Acorns mature in one growing
season and drop soon after ripening from September through November.
Acorns exhibit no dormancy and germinate soon after dropping [47].

Related categories for Species: Quercus stellata | Post Oak