Associated Forest Cover
provided by Silvics of North America
American hornbeam is typically an understory species and only
rarely occurs in the overstory or dominates a stand. It is
present in the following forest cover types (Society of American
Foresters) (22): Northern Forest Region, Black Cherry-Maple (Type
28), Beech-Sugar Maple (Type 60); Central Forest Region, White
Oak-Black Oak-Northern Red Oak (Type 52), White Oak (Type 53),
Northern Red Oak (Type 55), River Birch-Sycamore (Type 61), Pin
Oak-Sweetgum (Type 65); Southern Forest Region, Swamp Chestnut
Oak-Cherrybark Oak (Type 91), Sweetgum-Yellow-Poplar (Type 87).
American hombeam is found in a wide variety of forest communities
and with many tree species because its habitat frequently is an
ecotone in which species from wet and mesic sites intergrade. In
the North, it is a minor component of many different types,
infrequently becoming the first or second most abundant tree
species in the subcanopy layer (32). It is associated with
northern hardwoods and their wet site variants. Sugar maple (Acer
saccharum) and/or American beech (Fagus grandifolia) are
dominant in many situations but may be replaced by eastern
hemlock (Tsuga canadensis), yellow birch (Betula
alleghaniensis), red maple (Acer rubrum), American
elm (Ulmus americana), silver maple (Acer
saccharinum), and black ash (Fraxinus nigra) on
wetter sites.
In the central portion of its range, American hornbeam also is a
minor component of stands. Species dominant in northern stands
also dominate here along with white (Quercus alba), black
(Q. Velutina), northern red (Q. rubra), scarlet
(Q. coccinea), pin (Q. palustris), and chinkapin
(Q. muehlenbergii) oak; bitternut hickory (Carya
cordiformis); black tupelo (Nyssa sylvatica); sweetgum
(Liquidambar styraciflua); yellow-poplar (Liriodendron
tulipifera); river birch (Betula nigra); and basswood
(Tilia americana).
The species attains its greatest prominence in southern stands,
yet remains a member of the understory. In a number of areas it
is the most numerous of all tree species in the stand (36,40). It
is found in southern mixed hardwood and loblolly pine (Pinus
taeda) forests. Overstory species that frequently dominate
these stands are sweetgum, water Quercus nigra), white,
laurel (Q. laurifolia), willow (Q. phellos), cherrybark
(Q. falcata var. pagodifolia), and swamp chestnut
(Q. prinus) oak, American beech, black tupelo, red maple,
loblolly pine, southern magnolia (Magnolia grandiflora), and
yellow-poplar.
The species is also an important member of some nonforest
vegetative types in the Northeast. It is an early migrant and
forms pure stands in moist old fields (61) and grows in
persistent shrub communities in old pastures on hilltops and more
exposed hilltops (20).
Understory tree species associated with American hornbeam
throughout much of its range include eastern hophornbeam (Ostrya
virginiana), flowering dogwood (Cornus florida), witch-hazel
(Hamamelis virginiana), the serviceberries (Amelanchier
spp.), and speckled alder (Alnus rugosa). Northern
associates are striped (Acer pensylvanicum) and mountain
maple (A. spicatum). Red mulberry (Morus rubra), pawpaw
(Asimina triloba), and eastern redbud (Cercis
canadensis) are common associates from the Central States
southward. In the South, associated species include sourwood (Oxydendrum
arboreum), possumhaw (Ilex decidua), American holly
(Ilex opaca), winged elm (Ulmus alata), sweetbay
(Magnolia virginiana), water-elm (Planera aquatica),
parsley hawthorn (Crataegus marshallii), riverflat
hawthorn (C. opaca), common persimmon (Diospyros
virginiana), and Carolina laurelcherry (Prunus
caroliniana).
Shrub species associated with American hornbeam throughout its
range include spicebush (Lindera benzoin) and southern
arrowwood (Viburnum dentatum). In the northern half of
its range, American hombeam is associated with mapleleaf viburnum
(Viburnum acerifolium), redberry elder (Sambucus
pubens), common winterberry (Ilex verticillata), and
alternateleaf dogwood (Cornus alternifolia). In the
southern half of its range it is associated with
devils-walkingstick (Aralia spinosa), beautyberry (Callicarpa
americana), Virginia-willow (Itea virginica), southern
bayberry (Myrica cerifera), sweetleaf (Symplocos
tinctoria), and tree sparkleberry (Vaccinium arboreum).
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Climate
provided by Silvics of North America
The climate varies greatly from north to south in this species
habitat. Mean annual precipitation ranges from 710 mm. (28 in) in
Minnesota to 1570 mm (62 in) along the Gulf Coast. Most
precipitation occurs during the growing season, April through
September. Mean January temperatures range from -13° C (8°
F) to 16° C (60° F) and the mean July temperatures
range from 16° C (60° F) to 29° C (84° F).
Frost-free periods are from 80 to 320 days.
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Damaging Agents
provided by Silvics of North America
Insect and disease damage is not a
serious problem with American hornbeam. The species is resistant
to frost damage; its succulent foliage can withstand temperatures
as low as -8.5° C (17° F) (1). The tree is very
windfirm. Recreational use in forested campgrounds disposes it to
increased disease infection, insect infestation and decline; it
is the tree least capable of withstanding such use of the 22
hardwood species evaluated (47).
American hornbeam is susceptible to fire. Wildfires severe enough
to kill the hardwood component of white oak stands in Rhode
Island eliminated American hornbeam (10). Normally, the species
made up 6 percent of the understory stems. However, neither a
crown fire nor a ground fire affected the status of American
hornbeam in the ninth year after burning a loblolly pine stand in
North Carolina (42).
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Flowering and Fruiting
provided by Silvics of North America
The species is monoecious, with
male and female catkins borne separately on the same tree and
first appearing in the spring concurrently with leaf-out. Catkins
are green to brown with red on the scales. Staminate catkins are
pendant from lateral, short branches and 3 to 4 cm (1.25 to 1.5
in) long. Pollen matures and is wind disseminated in the spring
(63). Pistillate catkins are 13 to 19 mm. (0.5 to 0.75 1) long
and occur in spikelike groups at the terminus of leafy shoots.
Flowering occurs between March 20 and May 6 in the Southeast and
during April through May in the North.
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Genetics
provided by Silvics of North America
An American hornbeam, variety virginiana, is recognized by some
authorities but its validity is questionable. It replaces the
typical form in the northern half of the species range with some
overlapping in the Central States. The two forms are separated by
features of the bract of the fruiting
ament and the leaves, but in Ohio the two characteristics do not
necessarily vary at the same time, resulting in confusion (8).
American hornbeam exhibits clines (from north to south) in several
physiological and morphological properties. Fruit weights
increase northward (62); the length of cold preconditioning
required for bud bursting varies latitudinally (56), and the
specific gravity of the wood is higher for trees growing north of
latitude 36°N. than for trees growing at latitudes 31°
to 36° N. (55).
The species has eight pairs of chromosomes (63).
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Growth and Yield
provided by Silvics of North America
American hornbeam is unsuited for
commercial timber production because it is usually small,
twisted, and multi-stemmed. In undisturbed stands, from 70 to 93
percent of the American hornbeam. were saplings less than 13 cm
(5 in) d.b.h., and less than 1 percent were 25 cm (10 in) d.b.h.
or larger (21,40), which is a common minimum diameter for saw
logs. Heights of mature individuals generally range from 5 to 6 m
(15 to 20 ft) in Canada and from 8 to 11 m (25 to 35 ft) in the
South. The largest individual was found in New York. It has a
diameter of 70 cm (27 in), a height of 20 m (65 ft), and a crown
spread of 20 m (66 ft) (29).
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Reaction to Competition
provided by Silvics of North America
American horn beam is a very
shade-tolerant species, capable of persisting in the understories
of late seral and climax communities. Tolerance is greatest among
seedlings and declines as the trees age, requiring an opening in
the canopy for the species to reach maturity. It is one of a few
species in both northern and southern forests whose abundant
reproduction assures its replacement in stands across a wide
spectrum of sites (27,35). This is evidenced by an
inverse-J-shaped diameter distribution for the species in many
stands. On certain southern sites the species is so aggressive
that it will replace overstory species lost through logging or
catastrophe and prevent larger species from reproducing (17,30).
Ecologists consider American hombeam a member of near-climax to
climax communities. In Wisconsin where climax species are
assigned a climax adaptation number of 10, American hombeam is
rated 7 and 8 on uplands and 8 and 9 on lowlands for the northern
and southern parts of the State, respectively (16). Similarly the
species is rated 7 in New Jersey (11). It is ranked fifth highest
among 79 Central States species on the basis of a multivariate
analysis of various species characteristics that favor
establishment and growth under climax forest conditions (58).
American hornbeam first appeared in seral communities developing
on old fields about 12 to 18 years after the sites were abandoned
in North Carolina (41) and about 25 to 40 years after the sites
were sapling-sizeabandoned in New Jersey (26). It enters these
communities as a minor component when a sapling-size tree-shrub
community is dominant. In much older stands in North Carolina it
is more abundant. In maturing second-growth hardwood stands in
Connecticut, hornbeam had initially been an important species,
the most abundant one, in fact, on moist sites. But, over a
50-year period it declined in density, basal area, and ingrowth,
eventually becoming a minor component of all stands (53).
In forests managed for commercial timber production, American
hornbeam is considered a weed and is discriminated against in
stand improvement. Although hornbeam is considered difficult to
kill, herbicides have been effective. Mistblowing a mixture of
2,4-D and 2,4,5-T and injecting 2,4-D, Tordon 101, and Tordon 144
have killed 90 percent or more of the tops (43,44). Prescribed
burning is used to control the understory hardwoods, including
American hornbeam, that become established under southern pines.
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Rooting Habit
provided by Silvics of North America
No information available.
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Seed Production and Dissemination
provided by Silvics of North America
The fruit is an ovoid,
ribbed, 5 to 8 mm (0.2 to 0.3 in) long nutlet. It matures in one
season, changing from green to light-greenish-brown or brown on
maturity. The nutlet is borne at the base of a distinctive
three-lobed involucre, about 2.5 cm (I in) long; these occur in
clusters 5 to 10 cm. (2 to 4 in) long. The averages reported for
nutlets per kilogram range from 66,000 to 88,000 (30,000 to
40,000/lb), while the range is between 33,000 and 143,000 (15,000
and 65,000/lb) (48,62). Large seed crops occur at 3- to 5-year
intervals. Seeds are primarily dispersed by birds but are also
dispersed short distances by wind. Germination is epigeal.
Germination capacity of stratified seed is low-usually less than
60 percent and occasionally as low as 1 to 5 percent-but 100
percent germination was obtained using immature green seed (54).
Dormancy occurs in both the embryo and endosperm (48).
Stratification at 4° C (40° F) for 18 weeks,
stratification plus gibberellic acid treatment, and scarification
of the seed coat plus gibberellic acid treatment all improve
germination (9).
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Seedling Development
provided by Silvics of North America
The types of seedbeds and
environments favorable to establishment under natural conditions
has to be surmised from nursery experience and the habitat
preference of established plants. The optimum nursery seedbed has
soils that are rich, loamy, and continuously moist and the site
is free of extreme environmental change (48). This approximates
natural conditions where the species is most frequently found.
Abundant natural reproduction in undisturbed forests indicates
the species ability to become established on leaf litter seedbeds
under deep shade and with competition from other species (12,50).
The species also becomes established on sites that are wetter and
drier than optimum, as well as on open sites.
American hornbeam responds well to various degrees of overstory
removal in regeneration harvests. In two hardwood seed-tree
harvest areas in southeastern Arkansas, the proportion of
American hornbeam in the reproduction increased during the 18
years after cutting (30). Regeneration of the species consisted
of advance reproduction, new seedlings, stump sprouts, and root
suckers. Sprouts grew from 1.2 to 1.5 m (4 to 5 ft) in the first
year. By the 18th year, American hornbeam was becoming
subordinate in diameter to sweetgum and the red oaks. The species
also responded well to release after clearcutting
hemlock-hardwoods in southern New England (34). However, density
and basal area stocking of American hornbeam in relation to other
species were unaffected after a partial harvest of a
pine-hardwood stand in Louisiana (6).
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Soils and Topography
provided by Silvics of North America
Best growth and development of American hornbeam occurs on rich,
wet-mesic sites, but it is not restricted to such sites and can
tolerate a wide variety of conditions. Habitat requirements and
tolerances of the species are similar across its range.
Soils primarily associated with the species are in the orders
Alfisols, Ultisols, and Inceptisols but American hornbeam also
occurs on Entisols, Spodosols, Histosols, and Mollisols.
The best sites may be characterized as having abundant soil
moisture but sufficient drainage to prevent saturation and poor
aeration of the soil during the growing season (4,51). Typically,
the best sites are alluvial or colluvial soils in the transition
zone between mesic and wet areas (46), as near lakes and swamps
(35), on well-drained terraces of rivers (32,45), terraces or
steep slopes of minor streams with some gradient (39), coves,
ravine bottoms (33), and rises in lowlands (40). Surface soil
layers are somewhat poorly to well drained but the subsoil may
not be as well drained, may have a high fluctuating water table,
or may be of heavier texture. Soil water-holding capacity usually
is high (15,49). Upper soil horizons are primarily loams or of
loam-influenced textures. Nutrients and organic matter tend to
accumulate on these sites (36), and calcium and magnesium in
particular are normally more abundant than in surrounding soils
(13). Soil pH tends to be acidic-normally from 4.0 to 5.6-but can
be as high as 7.4 (35).
The species also grows well on wetter sites, such as hardwood
swamps on mineral soils or mucks (3,37). The key appears to be
improving soil moisture conditions through the growing season
because the species is only moderately tolerant of flooding (14).
It is eliminated from sites inundated more than 25 percent of the
time (24). Accordingly, it is absent or rare on the wettest
sites, such as lower floodplain terraces, permanently inundated
areas, and swamps with peat soils.
American hornbeam also grows, to a lesser extent, on mesic to
xeric sites (5,19). In Florida and Ontario the species occurs
more often on dry-mesic than on mesic or xeric sites. The
dry-mesic sites in Ontario have a higher soil moisture retaining
capacity than the others (35). In hilly terrain it is found most
frequently on north aspects but also grows on ridge tops and on
south aspects where subirrigation of the site improves soil
moisture (51).
The upper altitudinal limit of American hornbeam is 910 m (3,000
ft) in the Great Smoky Mountains ' but it is much more common at
about 490 in (1,600 ft) (59).
Concentrations of potassium, nitrogen, calcium, and phosphorus in
the foliage of the species are low in comparison to those of
other species (2). American hornbeam leaf litter, on the other
hand, has high concentrations of these nutrients in relation to
other species (57).
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Special Uses
provided by Silvics of North America
American hornbeam is an important food of gray squirrels in
southern bottom-land hardwoods; otherwise it is of secondary
importance to wildlife (25). Seeds, buds, or catkins are eaten by
a number of songbirds, ruffed grouse, ring-necked pheasants,
bobwhite, turkey, and fox and gray squirrels. Leaves, twigs, and
larger stems are consumed by cottontails, beaver, and
white-tailed deer (18,25).
Reproduction is browsed by white-tailed deer throughout the
species range but it is not a preferred food (7,28). The species
is heavily used by beaver because it is readily available in
typical beaver habitat (38).
The orange and scarlet coloration in the fall make this an
attractive ornamental tree. It is not widely used, however,
because it is difficult to transplant and does not do well on
exposed sites (60).
The wood of American hornbeam is not important in commerce because
the tree is too small, but its tough, dense, and close-grained
wood is used for tool handles, levers, wedges, and mallets.
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Vegetative Reproduction
provided by Silvics of North America
No information available.
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Distribution
provided by Silvics of North America
American hornbeam is native to most of the eastern United States
and extends into Canada in southwest Quebec and southeast
Ontario. Its western limit is just beyond the Mississippi River
from north-central Minnesota to the Missouri River, where it
ranges southwestward into much of the Ozark and Ouachita
Mountains and eastern Texas. It grows throughout much of the
South but is absent from the Mississippi River bottom land south
of Missouri, the lowermost Gulf Coastal Plain, and the southern
two-thirds of Florida. Northward along the east coast, it is not
found in the New Jersey pine barrens, much of Long Island, Cape
Cod, northern and eastern Maine, and the White and Adirondack
Mountains. It is found in central and southern Mexico, Guatemala,
and western Honduras.
-The native range of American hornbeam.
- license
- cc-by-nc
- copyright
- USDA, Forest Service
Brief Summary
provided by Silvics of North America
Betulaceae -- Birch family
F. T. Metzger
American hornbeam (Carpinus caroliniana), also called
blue-beech, ironwood, water-beech, or lechillo (Spanish), is a
small slow-growing short-lived tree in the understory of eastern
mixed hardwood forests. The short, often crooked trunk covered
with a smooth slate gray bark is characteristically ridged,
resembling the muscles of a flexed arm. The wood is
close-grained, very hard, and heavy but little used because such
a small tree is rarely converted into sawed products.
- license
- cc-by-nc
- copyright
- USDA, Forest Service