BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Celtis laevigata | Sugarberry 



GENERAL BOTANICAL CHARACTERISTICS : 
Sugarberry is a moderately tall (60 to 100 feet [18-30 m]), native
deciduous tree [2,5,36].  Mature trees are typically 18 inches (46 cm)
in d.b.h., 80 feet (24 m) tall, with 30 feet (9 m) clear of branches in
good stands [36].  The crown is spreading and round-topped or oblong.
The bark of young trees is gray and smooth; mature trees develop corky
outgrowths that are scattered to dense with smooth areas in between
[15].  The roots of sugarberry are relatively shallow; it does not form
a distinct taproot and has only average resistance to windthrow.
Sugarberry has a moderately long life span, not usually living over 150
years [5].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual reproduction:  Sugarberry is polygamo-monoecious [2,5].
Individuals usually first produce seeds at 15 years; optimum seedbearing
years are from 30 to 70 years of age.  Good seed crops are produced most
years, some individuals produce good crops every year.  There are
approximately 2,000 to 2,400 cleaned seeds per pound (4,400- 5,300/kg)
[5].  Seeds have an innate dormancy, requiring cold stratification at 41
degrees Fahrenheit ( 5 deg C) for 60 to 90 days [2].  Vora [60] found
that sugarberry seeds germinated best with no treatments other than cold
stratification (i.e. acid scarification or gibberellic acid addition).

Sugarberry seeds are dispersed by mammals, birds and by water. 
Seedlings are intolerant of flooding [5,36].

Sugarberry tends to grow slowly; the average 10-year diameter increase
in natural stands is 1.5 inches (3.8 cm).  The best growth rates are
found in dominant trees at 2.5 inches (6.4 cm) in 10 years [36].

Vegetative reproduction: Sugarberry can be propagated by cuttings.
Small stumps sprout readily [5,36].


SITE CHARACTERISTICS : 
Sugarberry is found in moist alluvial woods and slough margins (but not
deep swamps) up to 600 feet (180 m) elevation [15,43].  It also occurs
on upland sites, although rarely.  It occurs on any soil type with fair
drainage, from sandy loams and rocky or alluvial soils to heavy black
clay [47].  Sugarberry is most often found on clay soils in the orders
Iceptisols and Entisols on broad flats or shallow sloughs within the
floodplains of major rivers, and on deep moist soils derived from
limestones, but will grow under a considerable range of soil and
moisture conditions [5].

Sugarberry cannot tolerate prolonged flooding or water-saturated soils
[28].  Hook [27] listed sugarberry as weakly tolerant to waterlogging,
and capable of living from seedling to maturity in soils temporarily
waterlogged for 1 to 4 weeks of the year, or about 10 percent of the
growing season.  In forested wetlands sugarberry grows best in the drier
areas.  Rising water levels (due to sea level rise, flooding,
impoundments etc.) will reduce sugarberry basal area in these forests
[10].

Sugarberry occurs in cedar (Jumiperus spp.) glades in the Nashville
basin, Tennessee, in mesophytic forests of the Mississippi embayment
section, and in the Oachita mountains of Louisiana on elevated rocky
surfaces subject to frequent floods [3].  Sugarberry is present as an
occasional component of hydric hammocks in Florida [58].

Sugarberry is found in humid climates, except in the extreme western
portion of its range in Texas and Oklahoma.  Average annual
precipitation ranges from 20 to 60 inches (510-1,520 mm).  Summer
temperatures average 80 degrees Fahrenheit (27 deg C) with extremes of
115 degrees Fahrenheit (46 deg C), and temperatures average 30 to 50
degrees Fahrenheit (-1 to 10 deg C) with extremes of -20 degreees
Fahrenheit (-29 deg C).  The average frost-free period ranges from 150
to 270 days [5,36].

Overstory associates not listed in Distribution and Occurrence include
winged elm (Ulmus alata), cedar elm (U. crassifolia), water oak (Quercus
nigra), southern red oak (Q. falcata), blackgum (Nyssa sylvatica),
persimmon (Diospyros virginiana), honeylocust (Gleditsia tricantuos),
red maple (Acer rubrum), boxelder (A. negundo), pecan (Carya
illinoensis), bumelia (Bumelia lanuginosa), persimmon (Diospyros
virginiana), and red mulberry (Morus rubra).  Shrub associates include
swamp-privet (Forestiera acuminata), roughleaf dogwood (Cornus
drummondii), swamp dogwood (C. stricta), hawthorn (Crataegus spp.), and
buttonbush (Cephalanthus occidentalis) [5,7,19,36,45].  Lianas occurring
with sugarberry include eastern poison-ivy (Toxicodendron radicans)
[19].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Seedlings of sugarberry can establish under most stands of southern
bottomland hardwoods; sugarberry is shade tolerant.  It will respond
when released, and can outgrow more desirable forest species.  When
established in the understory it has a very poor form (limby, short-
boled, crooked or forked) [5,36].  

Sugarberry will naturally invade oak plantations, establishing at a rate
of up to 43 stems per acre (105/ha) on 4- to 8-year-old sites [1].

Sugarberry commonly follows eastern cottonwood (Populus deltoides var.
deltoides) and black willow (Salix nigra) in succession on new land
created by rivers [31,48,54].  In succession on land disturbed by gravel
pit operations, sugarberry codominated 47-year-old sites with eastern
redcedar (Juniperus virginiana) but did not occur in large numbers on
younger sites, and may be replaced by winged elm and post oak (Quercus
stellata) on more advanced sites [40].  On Florida tree hammocks,
disturbances such as fire, hurricanes or logging that do not destroy the
roots of young hardwoods are likely to result in canopies containing
sweetgum, hornbeam (Ostrya virginiana), oaks (Quercus spp.), and
sugarberry [58].

In a well documented series of studies, Van Auken, Bush and their
associates [6,7,53,55,56,57] have demonstrated that sugarberry is an
important species in secondary succession on terraces of the San Antonio
River in Texas.  Abandoned farmland is colonized first by huisache
(Acacia smallii), a light-requiring leguminous shrub.  Sugarberry is
present in early seres, but its growth is suppressed by the low nitrogen
levels of the soils (but not, as is often the case, by the low light
levels).  In fact, sugarberry grows better under huisache canopies than
in the open.  As huisache matures, the soil nitrogen levels increase,
and sugarberry grows faster and eventually overtops huisache, which dies
out due to high nitrogen and low light levels.  Sugarberry either
remains dominant, or is eventually overtopped by other tolerant
hardwoods.  They conclude that sugarberry is a late successional species
that needs high soil nitrogen, and is capable of growing in shade, but
can grow in distrubed areas or grasslands at reduced rates depending on
the presence of competition and soil nitrogen levels.

Old-growth stands may include sugarberry as an important overstory
species [41].  However, Robertson and Weaver [46] found that in an
Illinois old-growth stand of sweetgum, green ash, and red maple,
sugarberry was represented in the overstory but not in the reproduction
layers (no seedlings or saplings).  An adjacent plot in the later stages
of secondary succession (about 75 years old) had some seedlings, but no
saplings in the reproduction layer.  Both the old-growth (implied climax
vegetation) and the seral plots had similar basal areas of mature
sugarberry.  One can infer from these reports that perhaps sugarberry
regeneration does not occur at a rate sufficient to maintain its
numbers.  Once the canopy is mature and other tolerant hardwoods are
recruited, sugarberry numbers will decrease.


SEASONAL DEVELOPMENT : 
Sugarberry flowers when the leaves first appear in spring, from March to
May, depending on latitude.  Fruit appears in July and August, ripening
into October.  The fruit is retained on the tree until midwinter [2].
Most or all leaves are lost by mid-December in the Rio Grande Valley,
Texas [63].

Related categories for Species: Celtis laevigata | Sugarberry