BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus prinus | Chestnut Oak 



GENERAL BOTANICAL CHARACTERISTICS : 
Chestnut oak is a medium-sized, native, deciduous, monoecious tree.  It
is long-lived and slow-growing.  At maturity, chestnut oak is usually 65
to 80 feet (20-24 m) tall and 20 to 30 inches (51-76 cm) in d.b.h., but
on good sites it can reach a maximum size of 100 feet (30 m) in height
and 72 inches (183 cm) in d.b.h.  Seedlings initially develop a deep
taproot, but saplings and larger trees have six to ten main lateral
roots extending 10 to 33 feet (3-10 m) from the root crown.  These roots
occur from near the soil surface to a depth of 36 inches (91 cm) [49].
The acorns are large [6].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  Seed production begins when the tree is about 20 years old.
Acorn crop sizes vary considerably from year to year with heavy crops
occurring only once every 4 to 5 years [49].  Good crops are dependent
on spring temperature patterns.  Above normal temperatures in early
April followed by subnormal temperatures in early May result in the best
acorn crops.  The early warm temperatures induce the early development
of staminate flowers and increase the development of viable pollen.  The
cool weather delays the pollen dispersal to coincide with pistillate
flower development, and the delay may also enhance ovary development.  A
gradual increase in the temperature from early spring to summer results
in poor crops.  Occasionally, a chestnut oak will produce 100 to 300
pounds (45-136 kg) of acorns, but this is rare.  Often a tree will
produce less than 10 pounds (4.5 kg) [64].  Chestnut oaks generally
produce fewer acorns than other upland oak species [49].

Dissemination is by gravity and squirrels [49], although white oak group
acorns are not dispersed by squirrels to the extent that red oak group
acorns are [66].  Very few (0.5 percent) available chestnut oak acorns
were buried by gray squirrels in a study of acorn preference [36].

Most chestnut oak acorns germinate at day/night temperatures of 65/50
degrees Fahrenheit (18/10 deg C).  Chestnut oak germination is enhanced
by 1 inch (2-3 cm) of leaf litter, but litter deeper than 2 inches (5
cm) is unfavorable.  The germination capacity of sound acorns is 90
percent.  A thick paenchyma layer in the chestnut oak acorn pericup
allows it to absorb and retain more moisture than acorns of other oak
species.  Consequently, they can germinate in dry soil [49].  The
germination of chestnut oak acorns was not greatly affected by treating
the soil with copper, lead, and zinc solutions, although acorns from
sites naturally high in metals had slightly higher survival than acorns
from sites with low background levels of metals [4].

In an oak-pine forest in the New Jersey Pine Barrens, 1-year-old
chestnut oak occurred in areas with deeper litter (an average of 1.4
inches [3.5 cm]) and less light (22 percent of available) than its
upland associate, scarlet oak (Q. coccinea).  Chestnut oak seedlings,
however, are not highly site specific because of the large energy
reserves in the acorns [11].

The roots of chestnut oak seedlings penetrate 5 to 6 inches (12.7-15.2
cm) before the unfolding of primary leaves, which are borne on stems 2
to 3 inches (5-7.6 cm) tall [40].  Seedling growth is slow.  Ten years
after establishment, seedling were 6 inches (15 cm) in a unthinned
forest, 9 inches (24 cm) in a thinned forest, and 58 inches (146 cm) in
a clearcut [49].

Vegetative:  If top-killed, chestnut oaks sprout vigorously from dormant
buds at the root crown.  Sprouts grow faster than seedlings.  Ten years
after clearcutting, some stump sprouts were larger than 21 feet (6.4 m)
tall.  Probably 75 percent of chestnut oak reproduction in the southern
Appalachian Mountains is of sprout origin [49].

Chestnut oak sprouting frequency is high compared to other upland oaks.
In one study in the Virginia Piedmont, the sprouting frequency of
chestnut oak was over 90 percent, regardless of season of harvest or
stump diameter [32].  Although chestnut oak initially produces large
numbers of sprouts, sprout clumps tend towards the survival of one to
three stems.  In one study, 5, 10, 15, 25, and 35 years after cutting,
the average number of sprouts per stump was 7.3, 3.8, 2.8, 2.3, and 1.9,
respectively [48].  Between the ages of 4 and 8, competition is
dominated by interaction between sprout clumps, not stem-to-stem
competition within a sprout clump [12].


SITE CHARACTERISTICS : 
Chestnut oak, an upland xerophytic species, commonly occurs on ridgetops
and upper slopes.  It occurs from sea level on the coastal plain of New
Jersey and Long Island, New York, to about 4,600 feet (1,400 m) in the
southern Appalachians [49].  It can occur on all aspects; however, it is
usually on south- and west-facing upper slopes and on north and easterly
aspects in the southern Piedmont [25,49,54].  In the Ridge and Valley
Province of central Pennsylvania, chestnut oak dominated the steep
inclines and xeric ridgetop communities.  It decreased in importance on
mesic sites, although on some coarse-textured valley and cove sites,
chestnut oak was codominant with white oak [56].

Chestnut oak is usually found on dry, rocky, infertile soil with a low
moisture-holding capacity, although it grows best in rich, well-drained
soils along streams [49].  In southeastern Pennsylvania, Keever [33]
discovered that many of the ridge sites that chestnut oak dominates have
good soil moisture.  Presumably, these ridges get more precipitation than
lower elevations.  It is unclear why other species are excluded from
these ridgetop sites, although its possible that more mesic species
cannot endure occasional drought, which may be more severe on these
sites [33].  The infertile rocky soil, steep slopes, and exposed
conditions may also select against other forest species [46].

In 51 upland hardwood stands in the Piedmont of Virginia, chestnut oak
was important on sites with low soil calcium, magnesium, and pH [19].
Chestnut oak is commonly found on acidic soils derived from sandstone,
quartzite, and coarse-grained schists [8,54].  

In the Hudson River Valley in New York, chestnut oak forests differed
significantly (P<0.05) from white oak-black oak-pignut hickory (Carya
glabra) forests and red maple (Acer rubrum) forests in several site
characteristics.  Chestnut oak forests were more likely to have exposed
bedrock (67 percent of the stands), have a higher percent cover of bare
ground by rocks (5.28 percent), and have deeper litter (1.3 inches [3.4
cm]) [24].

Overstory associates not mentioned in Distribution and Occurrence
include scarlet oak, post oak (Q. stellata), hickories, sweet birch
(Betula lenta), yellow-poplar (Liriodendron tulipifera), blackgum (Nyssa
sylvatica), sweetgum (Liquidambar styraciflua), black cherry (Prunus
serotina), black walnut (Juglans nigra), red maple, sugar maple (Acer
saccharum), sourwood (Oxydendron arboreum), and black locust (Robinia
pseudoacacia).  Shrub associates include blueberry (Vaccinium spp.),
dwarf chinkapin oak (Q. prinoides), mountain-laurel (Kalmia latifolia),
Rhododendron spp., sumac (Rhus spp.), greenbrier (Smilax spp.), grape
(Vitis spp.), and Ceanothus spp. [25,49].  Pure and almost pure stands
of chestnut oak have sparse ground vegetation [6].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Chestnut oak is intermediate in shade tolerance.  Chestnut oak
reproduction dies after a few years under a closed canopy, but if some
light penetrates to the forest floor, seedling sprouts may persist for
years.  The sprouts will respond to release.  Chestnut oak is excluded
from mesic sites by more rapidly growing species including
yellow-poplar, sugar maple, red maple, black cherry, northern red oak,
black oak, and white oak.  Post oak, scarlet oak, and pitch pine (Pinus
rigida) are better adapted than chestnut oak to some extremely xeric
sites [49].

In the absence of disturbance, red maple and other shade-tolerant
species will succeed old-growth chestnut oak on good sites [43].  On
some poor sites in the Appalachian Mountains, chestnut oak stands are
considered a physiographic climax [49].  Little [39] suggests a mixed
oak forest of black, white, chestnut, and scarlet oaks may represent a
physiographic climax association on upland sites in the New Jersey Pine
Barrens.

In a study of forest composition in North Carolina, chestnut oak showed
good regeneration over a 30-year period on low density rhododendron
(Rhododendron maximum) sites, suggesting chestnut oak will continue to
dominate these forests.  However, it may diminish with time in areas
where high rhododendron density inhibits regeneration [57].

Advance regeneration is released by gypsy moth defoliation of the
overstory canopy.  However, stands defoliated by gypsy moth in
Pennsylvania and Maryland will probabaly have a smaller oak component in
the future because of competing vegetation and insufficient numbers of
advance regeneration [30].

In forests in the Hudson River Valley in New York, the percent
occurrence of chestnut oak has increased from 2.1 percent in the period
before 1800 to 13.7 percent in 1984.  However, early land surveys may
have underrepresented chestnut oak because it occurs on poor sites and
inaccessible areas.  If it were not underrepresented, frequent logging
may have increased its importance in stands because of the superior
ability of chestnut oak to sprout from stumps [24].

A forest stand growth model was developed and used to compare the pre-
and post-chestnut-blight forest.  After 500 years without American
chestnut, the model showed chestnut oak increased in frequency in the
forests [65].


SEASONAL DEVELOPMENT : 
Flowers develop in the spring at the same time as leaf development [49].
In a 3-year study of chestnut oak phenology in Pennsylvania, staminate
flowers, borne on ephemeral catkins, usually emerged during the first
week in May, and leaves unfolded several day later.  Pistillate flowers
appeared in the axils of leaves on the current year's shoots, usually 5
to 10 days after the staminate flowers emerged [63,64].

Pollen dispersal, largely controlled by weather, usually occurs 10 to 20
days after the staminate flowers emerge [49].  Cool weather delays
pollen dispersal [64].

Acorns mature in one growing season and drop from early September to
early October, usually 2 to 5 weeks before the acorns of other upland
oaks drop.  Acorns exhibit no dormancy and germinate in the fall.  If
the temperature is below 61 degrees Fahrenheit (16 deg C), shoot
development is inhibited by an induced epicotyl dormancy, but root
development continues.  Normal shoot development resumes in the spring
[49].

Related categories for Species: Quercus prinus | Chestnut Oak