BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus velutina | Black Oak 



GENERAL BOTANICAL CHARACTERISTICS : 
Black oak is a medium- to large-sized, native, deciduous tree with an
irregularly rounded crown [56].  In a forest, the trunk is usually
branch-free for half the height of the tree [28].  Individuals may live
150 to 200 years.  On good sites, black oak may reach 150 feet (46 m) in
height and 48 inches (122 cm) in d.b.h., but most trees are 60 to 80
feet (18-24 m) tall and 24 to 36 inches (61-91 cm) in d.b.h. [56].
Black oak has a deep taproot and deep and widespreading lateral roots
[28].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  Black oak is monoecious.  Seed production begins when the tree
is about 20 years old, with maximum production occurring between ages 40
and 75.  Black oak is a consistent seed producer, with good acorn crops
every 2 to 3 years.  Seed dissemination is by squirrels, mice, bluejays,
and other animals, and by gravity.  Rodents and birds often cache acorns
in the soil [56].

Germination is hypogeal.  Burial in or contact with mineral soil and
coverage with a light layer of leaves are favorable conditions for acorn
germination [56].  In a study of black oak and white oak regeneration of
an old field in Michigan, seedlings were more likely to establish
initially in open patches because blue jays preferentially choose open
sites to cache acorns.  However, seedlings that colonized open patches
were not likely to survive beyond the first several years unless the
patch was subsequently invaded by herbaceous vegetation [24].

Seedling growth is slow; average annual height growth of seedlings in
Missouri during a 6-year period was 2.1 inches (5.3 cm) [35].  Seedlings
can survive drought conditions [56].

Vegetative:  Black oak sprouts from the root collar if top-killed or
cut.  Younger individuals are more likely to sprout than older
individuals.  The probability that a stump with a 1-year-old sprout will
have at least one dominant or codominant sprout at age 5 is predictable
from stump diameter.  The probability ranges from 1.0 for 3-inch (7.6
cm) stump diameters to 0.15 for 30-inch (76 cm) stump diameters [56].
Black oak has a low tolerance for multiple sprouts and tends toward the
survival of a single sprout per stump.  In one study, 5, 15, and 25
years after cutting, the average number of sprouts per stump was 7.5,
2.2, and 1.0 respectively [42].

Seedlings often die back and sprout numerous times, thus becoming
advance regeneration.  The roots of black oak saplings may be 10 to 20
years older than the tops [56].  Sprouts grow faster than seedlings.
Average annual height growth of sprouts in Missouri during a 6-year
period was 6.1 inches (15.5 cm) [35].  Generally, the bigger the old
stem is, the faster the height growth of its sprouts [56].


SITE CHARACTERISTICS : 
Black oak, an upland xerophytic species, can occur on all aspects and
slope positions, but tends to be more abundant on the drier southerly
and westerly aspects and on upper slopes and ridges [16,56].  Black oak
does not appear to be site-sensitive.  Its occurrence is more due to
fortuitous circumstance than inherent habitat requirements [16].
Although it grows best on moist, rich, well-drained sites, it is
sensitive to competition on these sites and is more often found on dry,
nutrient-poor, coarse-textured soils [56].  Black oak does not occur on
the serpentine soils of the Maryland Piedmont [68].  It often grows on
sandy or gravelly sites or heavy glacial clay hillsides.  Black oak is
found up to 4,000 feet (1,200 m) in the southern Appalachian Mountains
[56].

Black oak is less drought tolerant than post oak (Q. stellata), but more
tolerant than northern red oak and about as tolerant as white oak [57].
Its predominance on southerly and westerly aspects may be due in part to
drought tolerance.  In addition, the increased solar radiation on these
sites may facilitate early establishment and eventual dominance of black
oak [49].
 
Overstory associates of black oak not mentioned in Distribution and
Occurrence include pignut hickory (Carya glabra), mockernut hickory (C.
tomentosa), bitternut hickory (C. cordiformis), shagbark hickory (C.
ovata), American elm (Ulmus americana), slippery elm (U. rubra), white
ash (Fraxinus americana), black walnut (Juglans nigra), butternut (J.
cinerea), southern red oak, scarlet oak, chinquapin oak (Q.
muehlenbergii), red maple (Acer rubrum), black cherry, and blackgum
(Nyssa sylvatica) [56].

Common small tree associates include sassafras, flowering dogwood
(Cornus florida), sourwood (Oxydendron arboreum), eastern hophornbeam
(Ostrya virginiana), redbud (Cercis canadensis), pawpaw (Asimina
triloba), downy serviceberry (Amelanchier arborea), and American
bladdernut (Staphylea trifolia) [56].

Common shrub associates include blueberry (Vaccinium spp.),
mountain-laurel (Kalmia latifolia), witch-hazel (Hamamelis virginiana),
beaked hazel (Corylus cornuta), spicebush (Lindera benzoin), sumac (Rhus
spp.), and Viburnum spp. [56].

Herbaceous plants associated with black oak in sand savannas include
little bluestem (Schizachyrium scoparius), Pennsylvania sedge (Carex
pensylvanica), and Coreopsis spp. [8].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Black oak is intermediate in shade tolerance.  It is more tolerant than
black cherry or shortleaf pine (Pinus echinata), but less tolerant than
white oak, chestnut oak (Quercus prinus), hickories, maples (Acer spp.),
elms (Ulmus spp.), beech (Betula spp.), or blackgum.  Light is required
to recruit black oak seedlings into the sapling stage; seedlings
eventually die under a closed-canopy forest [29,56].

Black oak replaces pines (Pinus spp.) on heavily cutover areas.  It
succeeds sassafras and common persimmon (Diospyros virginiana) on upland
old fields [16].  In the Hudson River Valley in New York, stands
dominated by white oak, black oak, and pignut hickory occur on rocky,
nutrient-poor sites.  The open canopy, less distinct vertical
stratification of canopy trees, and diverse herbaceous understory
suggest these forests gradually invade old pasture sites [18].

Black oaks woodlands began invading savannas in Northern Illinois 2 to 3
years after the construction of roads which acted as functional
firebreaks [50].  In the past, the high presettlement fire frequency in
grasslands prevented black oak expansion [1]

The importance of black oak in many forests has declined since human
settlement.  In the absence of disturbance such as fire or windthrow,
black oak is succeeded by more shade-tolerant, mesophytic species.  A
decline in black oak has been documented in an old-growth oak-hickory
forest in southwestern Illinois.  Black oak had been dominant in the
forest since 1821, but it decreased in density and basal area between
1956 and 1983 due to senescence.  Sugar maple (Acer saccharum) has
increased in the forest.  It is believed that black oak originally
established on this site after the New Madrid Earthquake in 1811 or
after a hurricane shortly after the earthquake, both of which caused
much downed timber [59].

In the late 1700's and 1800's in Pennsylvania, massive logging to
provide wood for charcoal-fueled iron furnaces was accompanied by
wildfires.  The combination of logging and fire increased the relative
dominance of oaks, including black oak.  In the 20th century, fire was
suppressed and eventual logging of stands with understories dominated by
red maple, sugar maple, and black cherry accelerated the recruitment of
these mesophytic species into the canopy [2].

In the Hudson River valley in New York, early land surveys indicate the
white oak-black oak-hickory type was prevalent prior to forest clearing.
Since abandonment from agriculture, the type has returned but is not
nearly as important as it was.  The percent occurrence of black oak in
these forests was 15.3 percent in the period before 1800 and only 4.1
percent in 1984 [18].

In a black oak-white oak forest in southern Wisconsin, white oak is
replacing black oak.  Black oak, which is more susceptible to oak wilt
than white oak, is dying.  White oak is not regenerating in the forest
but because it is a longer lived, slower growing species, it is now
replacing black oak [41].

Succession is slow or unlikely in some oak forests on extremely xeric or
nutrient poor sites [1].  Blackjack oak and black oak forests on
extremely xeric, upland sites in Illinois did not exhibit signs of being
replaced by late successional species.  Self-maintenance was evident as
blackjack oak and black oak were important species in the sapling and
seedling layers as well as the overstory [3].  

Even in the absence of fire, succession towards a richer, mesophytic
forest appears slow or unlikely in a black oak-blueberry community on
the Lake Michigan sand dunes.  Black oak has low nutrient requirements
and is relatively ineffective in returning nutrients to the dune surface
in its litter.  The well-leached dunes remain dry and nutrient poor.
Fire aggrevates these conditions and helps perpetuate black oak on these
sites [52].

Some of the most xeric sites of the South Carolina Piedmont are occupied
by old-growth communities of black oak, post 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 [30].


SEASONAL DEVELOPMENT : 
Staminate flowers develop from leaf axils of the previous year.  Catkins
emerge before or at the same time as the current year's leaves, usually
in April or May.  Acorns mature in two growing seasons.  The acorns
ripen from late August to October depending on geographic location, drop
in the fall, and germinate in the spring [56].

Related categories for Species: Quercus velutina | Black Oak