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Wildlife, Animals, and Plants
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Introductory
SPECIES: Celtis occidentalis | Hackberry
ABBREVIATION :
CELOCC
SYNONYMS :
Celtis crassifolia
SCS PLANT CODE :
NO-ENTRY
COMMON NAMES :
hackberry
sugarberry
common hackberry
nettletree
beaverwood
northern hackberry
American hackberry
False elm
TAXONOMY :
The fully documented scientific name of hackberry is Celtis occidentalis
L. The taxonomy presented here follows that of the Great Plains Flora
Association [16] which designates three varieties of this species in the
Great Plains. Apparently the variation encountered within the species
makes recognition of these varieties difficult. Fully documented names
of the hackberry varieties encountered in the literature are presented
below [37].
Celtis occidentalis var. crassifolia (Lam.) Gray
Celtis occidentalis var. pumila (Pursh) A.Gray
Celtis occidentalis var. canina (Rafl) Sarg.
LIFE FORM :
Tree
FEDERAL LEGAL STATUS :
NO-ENTRY
OTHER STATUS :
NO-ENTRY
COMPILED BY AND DATE :
L. C. Rosario, August 1988
LAST REVISED BY AND DATE :
NO-ENTRY
AUTHORSHIP AND CITATION :
Rosario, Lynne C. 1988. Celtis occidentalis. In: Remainder of Citation
DISTRIBUTION AND OCCURRENCE
SPECIES: Celtis occidentalis | Hackberry
GENERAL DISTRIBUTION :
Hackberry is widely distributed in the eastern United States from
northwest Minnesota to central Wisconsin and Michigan into central New
York and throughout the southern New England states. It is found as far
south as northern Georgia, Alabama, northeastern Mississippi and central
Arkansas. This species' range extends west through central Oklahoma,
and includes most of Kansas, Nebraska, South Dakota and eastern North
Dakota [21]. Hackberry also grows along the Arikaree river in eastern
Colorado [4]. In Canada hackberry is local in the extreme southern
reaches of Manitoba, Quebec and Ontario [17]. The exact southern part
of its range is difficult to establish because of hackberry's similarity
to sugarberry (C. laevigata) [21].
ECOSYSTEMS :
FRES14 Oak - pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
FRES17 Elm - ash - cottonwood
FRES18 Maple - beech - birch
FRES21 Ponderosa pine
FRES28 Western hardwoods
STATES :
AL AR CO CT DE FL GA IL IN IA
KS KY MD MA MI MN MS MO NH NJ
NY NC ND OH OK PA RI SC SD TX
VT VA WV WI MB ON PQ
ADMINISTRATIVE UNITS :
AMIS ANTI BADL BISO BLRI BICA
BUFF CAMO CHCH COLO COSW CUGA
CUVA DEWA DINO EFMO FOCA FODO
GATE GWCA GWMP GRSM HOBE HOSP
MACA MANA NERI OZAR PIPE RICH
ROCR SHEN TICA VAFO WICR WICA
BLM PHYSIOGRAPHIC REGIONS :
14 Great Plains
15 Black Hills
16 Upper Missouri Basin and Broken Lands
KUCHLER PLANT ASSOCIATIONS :
K17 Black Hills pine forest
K81 Oak savanna
K82 Mosaic of bluestem prairie and oak - hickory forest
K84 Cross timbers
K89 Blackbelt
K98 Northern floodplain forest
K99 Maple - basswood forest
K100 Oak - hickory
K101 Elm - ash forest
SAF COVER TYPES :
26 Sugar maple - basswood
40 Post oak - black oak
42 Bur oak
46 Eastern redcedar
60 Beech - sugar maple
61 River birch - sycamore
62 Silver maple - American elm
93 Sugarberry - American elm - green ash
94 Sycamore - sweetgum - American elm
235 Cottonwood - willow
236 Bur oak
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
HABITAT TYPES AND PLANT COMMUNITIES :
Hackberry is a documented member of two plant communities in the western
extension of its range. It is listed as an associated species of the
green ash (Fraxinus pennsylvanica)/western snowberry (Symphoricarpos
occidentalis) plant communities in Nebraska and in the Black Hills
National Forest of South Dakota, and in the plains cottonwood (Populus
sargentii)/western snowberry plant communities in central Montana,
southwestern North Dakota, southcentral South Dakota and Thunder Basin
National Grassland of Wyoming [20]. No published classification schemes
were encountered for the eastern extension of hackberry's range.
VALUE AND USE
SPECIES: Celtis occidentalis | Hackberry
WOOD PRODUCTS VALUE :
Hackberry wood is of medium hardness and strength, white to yellowish in
color and rather elastic [25,30]; its specific gravity is 0.49 [25].
This wood makes excellent fuel, almost equaling hickory, and is used
also in the manufacture of cheap furniture. The technical qualities of
hackberry wood resemble those of elm (Ulmus spp.) and white ash
(Fraxinus americana), and it is sometimes used as a substitute for these
species. Hackberry is not a commercially important tree (except as
firewood) with its low timber value, but when peeled and properly
seasoned hackberry poles serve many useful purposes. However, the wood
is not durable when in contact with the soil [29,30].
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
The fruit of hackberry, a sweet, edible drupe, is eaten by many small
birds and mammmals. These berries persist though the winter, but most
are consumed or fall off by the spring [34]. Over 25 species of birds
feed on hackberries, including: wild turkey, ring-necked pheasant,
quail, prairie sharp-tailed grouse, lesser prairie chicken, cedar
waxwing, yellow-bellied sapsucker, mockingbird, robin, bobwhite and
others [21,23,34,41]. The fox squirrel will feed on both the fruit and
the nipple galls [21].
Deer will browse on the leaves of hackberry [34], but generally elk,
deer and antelope do not prefer hackberry over other browse species
[10].
This tree is not poisonous to livestock, but with poor palatability and
poor protein value, it is not considered to be a preferred species [10].
PALATABILITY :
Dittberner and Olson [10] rate the palatability of hackberry as poor for
cattle, sheep and horses in Utah.
Palatability for wildlife is rated as follows [10]:
UT ND
Elk fair ----
Mule deer fair poor
White-tailed deer ---- good
Antelope poor poor
Upland game birds fair ----
Waterfowl poor ----
Sm nongame birds fair good
Sm mammals fair ----
NUTRITIONAL VALUE :
The nutritional value of hackberry is relatively low for livestock, with
fair energy value and poor protein value [10].
COVER VALUE :
Hackberry, as a member of several riparian and wooded draw communities,
provides valuable cover for wildlife and livestock, especially in the
plains regions where quality cover is often lacking. The degree to
which this species provides environmental protection during one or more
seasons for wildlife species is as follows [10]:
UT ND
Elk fair ----
Mule deer good poor
White-tailed deer ---- good
Antelope poor poor
Upland game birds good ----
Waterfowl poor ---
Sm nongame birds good fair
Sm mammals good ----
VALUE FOR REHABILITATION OF DISTURBED SITES :
Dittberner and Olson [10] report that hackberry has fair growth on
acidic and saline soils, poor growth on sodic-saline soils, and has a
medium erosion control potential. Although hackberry thrives better on
fertile soils than on poor ones, its ability to grow on sterile soil is
one of its best qualities. This tree will live and bear seed in
situations where almost any other tree would die. In more humid regions
it grows on dry, sometimes barren soil, and on the semiarid Plains, it
thrives best along water courses. This species seems to favor limestone
soils [30]. Due to these characteristics, especially its ability to
withstand drought [3], and its growth in a wide variety of sites and
soils, [10,21], this species may be of some value in reclamation of
disturbed sites.
Field plantings by the Soil Conservation Service have resulted in
commercial production and extensive use of native trees such as
hackberry, among other species, in windbreaks and shelterbelts for
control of wind erosion [26]. In the central Great Plains, hackberry,
with a medium crown density, deep rooting habit, and high drought
resistance, is recommended for windbreak plantings on deep, moist,
permeable soils (in river and creek bottoms) and on medium upland soils
(silty or clayey loams) [33]. Since hackberry is susceptible to early
fall freezes and is frequently killed back severely by late-spring
frosts, George [15] recommends planting this tree in the second or third
row of either the windward or the leeward half of the windbreak. For
best growth, George [14] also recommends planting hackberry under
irrigation and on dryland sites where the moisture supply is favorable.
Byrd [9] lists hackberry, among other species, as useful for planting in
impacted recreation areas where soil moisture or innundation is likely
to be excessive for several weeks at at time.
Hackberry may be propogated by layering, by cutting, and by seed [41].
Fruit should be collected after the leaves fall in September or October,
or as late as winter. It may be handpicked, flailed or shaken from the
tree [43]. Drying the fruit is not necessary unless it is picked early
in the season. Depulping the seeds is not essential, but it has been
shown to aid germination; fermenting the fruit for three days at room
temperature, and then depulping it prior to stratification should give
excellent results [7]. The dried fruit or cleaned seeds store equally
well in sealed containers at 41F (5C). Hackberry seeds have been stored
in this manner for 5 1/2 years without a loss in viability. There are
about 2050 fruits/lb or 3500 to 5400 cleaned seeds/lb [7].
Hackberry seeds may be sown untreated in the fall, or in the spring
after stratification, as the seeds do exhibit dormancy. To break
dormancy, stratification at 41F (5C) in moist sand or other suitable
media for 60 to 90 days is sufficient [7]. Seeds may also be treated
with concentrated sulphuric acid for 1 hour, be washed in water, and be
treated an additional hour in the concentrated sulphuric acid. This
stratification method gives 84% germination in 55 days as compared to
22% germination in 65 days after stratification at 41F (5C) for 60 days
[41].
Either fall-sown or spring-sown stratified seeds should be broadcast or
drilled in rows about 8 to 10 inches (20-25cm) apart and covered with
1/2 inch (1cm) of firmed soil. Beds should be mulched with straw or
leaves held in place with bird screens until germination starts [7].
OTHER USES AND VALUES :
Hackberry, first cultivated in 1656 [7], has no showy flowers or
colorful fall foilage, and is therefore not often selected for
ornamental planting [4], although it is an excellent shade tree,
rivaling American elm (Ulmus americana) [30]. However, it is widely
planted in windbreaks and landscaping, mostly because of its ability to
tolerate drought [41]. Apparently a coarse thread suitable for ropes
and matting is obtained when the bark is steeped in water until the
fibers separate [17]. Also, the berries and seeds of hackberry are
eaten by many species of birds [39], making this species useful for
increasing habitat and natural food supplies for birds frequenting
residential areas.
MANAGEMENT CONSIDERATIONS :
Although hackberry will endure drought conditions [3], this species
grows poorly under dryland conditions [14]. It is recommended that this
species be planted for windbreak and ornamental purposes under
irrigation, or on dryland sites where the moisture supply is favorable
[14].
In the northern reaches of its range, especially in the northern Great
Plains, hackberry is highly susceptible to early fall freezes and is
frequently killed back severely by late spring frosts. It is
recommended that this species be planted on moist sites in the second or
third row of either the windward or the leeward half of the windbreak
[15].
Hackberry will also tolerate excessive soil moisture, and is therefore
recommended for planting in recreation areas where soil moisture or
innundation is likely to be excessive for several weeks at a time [9].
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Celtis occidentalis | Hackberry
GENERAL BOTANICAL CHARACTERISTICS :
Hackberry is a native, deciduous small to large tree, its size varying
in response to habitat [16]. In poor, dry sites, growth is so stunted
that the plant appears as a shrub. This drought and flood tolerant tree
grows up to 82 feet (25m) high with the larger branches 26 to 33 feet
(8-10m) above the ground [37], although on the Great Plains and on dryer
sites it usually grows to only 25 to 50 feet (7.5-15m) high with a
diameter of 8-24 inches (20-61cm) [21]. On the best sites hackberry may
reach 130 feet (40m) with a diameter of 4 feet (1.25m) [21]. The rather
thick (1 to 1 1/2 inches (2.5-4cm)), dark brown to grey bark is deeply
furrowed, checkered and warty when older; the younger branches are
mostly pubescent [16,31]. Hackberry has lateral roots which tend to be
medium deep to shallow [31,41].
Early growth of hackberry varies greatly within its range. Height
growth may not exceed 1 inch (2.5cm)/year under a heavy overstory, but
when planted in Great Plains shelterbelts, plants average 1.3 feet
(40cm)/year during the first 6 years [34]. Maximum age attained by
hackberry is between 150 and 200 years [21].
The simple, alternate leaves are lance-ovate or deltoid from 2 to 4.5
inches (5-12cm) long and 1.2 to 2.4 inches (3-6cm) wide with a serrate
margin. The lower surface of the leaves is paler and pubescent [16,37].
This monoecious tree has perfect, unisexual flowers which appear in the
spring as the new leaves emerge [17]. The inconspicuous, small, green
flowers are wind-pollinated [34]. Staminate flowers appear singly or in
clusters of two to three at the base of a short, green branch.
Pistillate flowers appear singly or in pairs [37].
Hackberry fruit is a round drupe with a thin, sweet, edible pulp
enclosing a bony, cream-colored nutlet. The fruit, which is usually
variable in size, form and color [21] is dark orange or red to dark
purple or black in color, and is about 1/4 to 1/3 inch (0.5-1cm) in
diameter on a 2/3 inch (15mm) pedicel [7,16,17,37]. Hackberry produces
good seed crops each year [43].
Hackberry is host to a large number of insects and diseases, most of
which cause no serious damage. Four gall-producing insects attack this
tree, and the entire crown may be defoliated by the spiny elm
caterpillar or the hackberry butterfly caterpillar. The hackberry
engraver beetle attacks mostly dead or dying branches, but has been
reported to attack living sapwood as well, causing the tree to die. A
witches'-broom caused by the mite Eriophyes spp. and a powdery mildew
fungus causes a rosette-like proliferation of the branch tips, but does
not cause serious damage to the tree [21,41].
Many ecotypes of this variable species are known to occur. Varieties
are distinguished by such morphological charcteristics as growth form,
height, leaf size and margin, and fruit shape and color.
RAUNKIAER LIFE FORM :
Undisturbed State: Mesophanerophyte
Undisturbed State: Microphanerophyte
Burned or Clipped State: Therophyte (offsite)
Burned or Clipped State: Chamaephyte
REGENERATION PROCESSES :
Hackberry regenerates primarily through sexual reproduction. This tree
produces good seed crops most years, with at least some seed produced
each year [7,21]. Although some seed may be dispersed by water, most is
disseminated principally by birds and small mammals. The fruit, a drupe
with sweet, edible pulp [37], is consumed by many species of birds and
mammals, which then disperse the seeds in their feces [34]. Some fruit
stays on the tree through the winter, but most is consumed or falls off
before spring [34,43].
This shade tolerant species is a member of several late seral and climax
communities, reproducing even in heavy shade [11,21,35]. Hackberry
seedlings become established in existing hardwood stands, but rarely in
old fields, and seedlings and saplings have been observed growing in
heavy shade where seedlings of other overstory species did not persist
[21]. Height growth may only be 1 inch (0.5cm)/year under heavy
overstory [21].
Krajicek [21] reports that when cut, hackberry will produce sprouts from
the stumps of small trees, but rarely from those of larger trees,
However, there is little other evidence in the literature of this
species' ability to sprout. On the Konza prairie in Kansas, hackberry
is replacing the more heliophilous (sun-loving) bur and chinkapin oaks
(Quercus macrocarpa and Q. muehlenbergii), only where fire has been
excluded, as fire kills the seedlings and saplings [34]. This suggests
that hackberry is unable to sprout after fire or to reproduce in the
openings it creates.
SITE CHARACTERISTICS :
Hackberry is adapted to a variety of climatic conditions. Average
annual precipitation varies from 14 to 60 inches (35.5-155cm), and the
average frost-free season is from 120 to 250 days. Hackberry tolerates
an annual temperature variation of 140F (60C) in the Great Plains [21].
However, the northern extension of its range is limited by late spring
frosts which destroy flowers, or by early autumn frosts which kill the
germs of immature fruits. It grows best on moist valley soils along
streambanks and on flood plains [16] but is also commonly found on
slopes and bluffs, on limestone outcrops, on the north side of sand
dunes in western Nebraska, on upland sites in the central Great Plains
under existing oak stands on all aspects, slopes and ridges, on rocky
hillsides in open woodlands [21], and along the base of canyon walls of
the Arikaree River in Colorado [4]. In the northern Great Plains
portion of its range, where rainfall is insufficient to support upland
tree growth, hackberry is restricted to well developed river valleys,
north slopes and protected ravines, and is absent from the windswept
parts of the western river valleys [21].
Although principally a bottomland tree, sites with a permanently high
water table are unfavorable for hackberry; however, periodic flooding is
not detrimental. In Kentucky, 46 days of flooding during one growing
season caused no apparent damage to this tree [21]. This species has
been planted frequently in the west because of its relative drought
tolerance/avoidance [31], but mesic hackberry is less successful at
coping with water stress than bur and chinkapin oaks (Quercus macrocarpa
and Q. muehlenbergii) [2].
Hackberry is tolerant of a variety of soils, but grows best on moist,
rich soils [21]. Its growth is stunted and scraggly on poor, dry sites
[31]. This species seems to prefer limestone soils [21].
Hackberry seldom occurs in pure stands, although it is prominent in the
northern phase of the sugarberry (Celtis laevigata) - American elm
(Ulmus americana) - green ash (Fraxinus pennsylvanica) forest cover
type. It also occurs in several upland forest types in association with
sugar maple (Acer rubrum), basswood (Tilia spp.), post oak (Quercus
stellata), black oak (Q. velutina), bur oak (Q. macrocarpa), and eastern
redcedar (Juniperus virginiana) [11,21]. In the central Great Plains,
hackberry is reproducing under chinkapin oak and bur oak stands, and is
replacing the oak woodlands as the major overstory dominant [34].
The elevational ranges for hackberry in several northern Great Plains
states are as follows [10]:
Colorado 3,500-7,200 feet (1,067-2,195m)
Montana 4,000-4,500 feet (1,219-1,372m)
Nebraska 2,600-4,500 feet (792-1,372m)
South Dakota 3,000-3,500 feet (914-1,067m)
Utah 4,800 feet (1,463m)
Wyoming 4,800 feet (1,463m).
SUCCESSIONAL STATUS :
Hackberry is found in many forest types ranging from early to late
seral, making its successional position difficult to determine.
This tree is intermediate to tolerant in its ability to withstand shade
and seems to require shade for reproduction of its seedlings [21]. In
the Konza prairie of the central Great Plains where fires are excluded,
succession is progressing from oak dominated woodlands to forests
dominated by hackberry. Abrams [1] states that on the more mesic sites
of the Konza prairie, hackberry may be the future sole dominant of what
are now oak woodlands. Hackberry also establishes itself on river
floodplains of the central Great Plains under willow (Salix spp.) and
eastern cottonwood (Populus deltoides), and is probably the climax
species [5]. This species is also a member of several late-seral
communities [11,35].
SEASONAL DEVELOPMENT :
Hackberry, a polygamo-monoecious tree, flowers when the leaves emerge,
or shortly after, in early April in the southern part of its range, and
in late May in the northern part. The fruit, a drupe, ripens from
September to October, and remains on the tree throughout the winter
[7,21]. This deciduous tree drops its leaves in the fall, generally
after the first frost.
FIRE ECOLOGY
SPECIES: Celtis occidentalis | Hackberry
FIRE ECOLOGY OR ADAPTATIONS :
There is virtually no direct information in the literature to indicate
hackberry's adaptation to disturbance by fire. A flood tolerant species
[21] with moderately thick bark when mature [31], hackberry will sprout
from the stumps of small trees, but rarely form those of large trees
[21]. However, Krajicek [21] reports that hackberry is highly
susceptible to fire damage which opens the way for wood decay organisms,
and due to its preferrence for reproduction under shade, it is doubtful
that hackberry seedlings would survive under full sunlight conditions
present as a result of burning [11,21,35]. On the Konza prairie of
Kansas, where hackberry is reproducing under the shade of heliophilous
(sun-loving) bur and chinkapin oaks (Quercus macrocarpa and Q.
muehlenbergii), there is evidence that hackberry is able to survive only
where fire is excluded as a natural component of the environment [34].
Sugarberry (Celtis laevigata), a member of the Celtis genus that
morphologically and ecologically is quite similar to hackberry, is
reported to be easily injured by fire. A light burn kills back
reproduction, and heavier burns may kill even the largest trees and
wound others, subjecting them to serious butt rot which advances rapidly
in this species [27]. This limited information suggests that hackberry
is not well adapted to disturbance by fire.
POSTFIRE REGENERATION STRATEGY :
secondary colonizer species;offsite seed transported to site after year 2
FIRE EFFECTS
SPECIES: Celtis occidentalis | Hackberry
IMMEDIATE FIRE EFFECT ON PLANT :
There is no direct fire effects information concerning hackberry.
Although this species has moderately thick bark (1 to 1 1/2 inches
(2.5-4cm)) when mature [31], and has been reported to sprout from small,
but not large tree stumps [21], on the Konza prairie there is evidence
that hackberry is able to survive only where fire is excluded as a
natural component of the environment [34]. Krajicek [21] reports that
hackberry is highly susceptible to fire damage, which opens the way for
wood decay organisms. Sugarberry (Celtis laevigata), a member of the
Celtis genus that morphologically and ecologically is quite similar to
hackberry, is reported to be easily injured by fire. A light burn kills
back reproduction, and more intense burns may kill even the largest
trees and wounds others, subjecting them to serious butt rot which
advances rapidlly in this species. However, there is some sprouting
from the root collars of fire-damaged seedlings and saplings [27]. This
information suggests that hackberry would generally not be resistant to
fire mortality.
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
PLANT RESPONSE TO FIRE :
Hackberry is generally thought to be intolerant to burning. This tree
is highly susceptible to fire damage, which opens the way for wood decay
organisms [21]. Seedling and saplings are killed by fire on the Konza
prairie [34], and Krajicek [21] states that small, and rarely large
trees will sprout from stumps. However, there is no direct information
to suggest that hackberry would sprout after burning, although
sugarberry (Celtis laevigata), a member of the Celtis genus that
morphologically and ecologically is quite similar to hackberry, is
reported to sprout from the root collars of fire-damaged seedlings and
saplings [27].
Since hackberry is a shade tolerant, late successional species
reproducing primarily under heavy shade [11,21,35], it is doubtful that
its seedlings would survive under the full sunlight conditions present
as a result of burning.
Because hackberry has moderately thick bark when mature (1 to 1 1/2
inches (2.5-4cm)) [31], it is possible that this tree could survive a low
intensity burn. However, sugarberry is easily injured by fire, and
heavier burns may kill even the largest trees and wound others, making
them subject to serious butt rot [27]. Response and recovery time
according to fire intensity, severity, and season of the burn has not
been documented for hackberry.
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS :
On the Konza prairie, or in other areas where hackberry is not
considered a valued species, it appears that fire can be used as a tool
to kill this tree and to convert woodlands back to their seral
successional stage, with oak (Quercus spp.) as the desired species [34].
However, in bottomland forest types where production of timber is the
primary objective, fire should not be used as a management tool [29].
Hackberry and other, more valuable timber species are susceptible to
fire damage, which opens the way for wood decay organisms [21].
References for species: Celtis occidentalis
1. Abrams, Marc D. 1986. Historical development of gallery forests in northeast Kansas. Vegetatio. 65: 29-37. [3255]
2. Abrams, Marc D.; Knapp, Alan K. 1986. Seasonal water relations of three gallery forest hardwood species in northeast Kansas. Forest Science. 32(3): 687-696. [256]
3. Albertson, F. W.; Weaver, J. E. 1945. Injury and death or recovery of trees in prairie climate. Ecological Monographs. 15: 393-433. [4328]
4. Bagley, Walter T. 1979. Hackberry--a hardy plant often overlooked. American Nurseryman. 150(3): 15,88-89. [4429]
5. Bellah, R. Glenn; Hulbert, Lloyd C. 1974. Forest succession on the Republican River floodplain in Clay County, Kansas. The Southwestern Naturalist. 19(2): 155-166. [241]
6. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434]
7. Bonner, F. T. 1974. Celtis L. Hackberry. In: Schopmeyer, C. S., technical coordinator. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 298-300. [7579]
8. Brutvan, B.; Klukas, R. (revised by R. Klukas). 1982. Checklist of plants of Wind Cave National Park.. [Place of publication unknown]: [Publisher unknown]. 32 p. On file with: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratoy, Missoula, MT. [374]
9. Byrd, Nathan A. 1978. Some effects of soil moisture on management of forest cover for recreation and aesthetics. In: Balmer, William E., ed. Proceedings--soil moisture...site productivity symposium; 1977 November 1-3; Myrtle Beach, SC. Atlanta, GA: U.S. Department of Agriculture, Forest Service, Southeastern Area, State and Private Forestry: 119-124. [4263]
10. Dittberner, Phillip L.; Olson, Michael R. 1983. The plant information network (PIN) data base: Colorado, Montana, North Dakota, Utah, and Wyoming. FWS/OBS-83/86. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 786 p. [806]
11. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905]
12. Fralish, James S.; Jones, Steven M.; O'Dell, R. Kent; Chambers, Jim L. 1978. The effect of soil moisture on site productivity and forest composition in the Shawnee Hills of southern Illinois. In: Balmer, William E., ed. Proceedings: Soil moisture...site productivity symposium; 1977 November 1-3; Myrtle Beach, SC. Atlanta, GA: U.S. Department of Agriculture, Forest Service, Southeastern Area, State and Private Forestry: 263-285. [4268]
13. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others]. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998]
14. George, Ernest J. 1953. Tree and shrub species for the Northern Great Plains. Circular No. 912. Washington, DC: U.S. Department of Agriculture. 46 p. [4566]
15. George, Ernest J. 1953. Thirty-one-year results in growing shelterbelts on the Northern Great Plains. Circular No. 924. Washington, DC: U.S. Department of Agriculture. 57 p. [4567]
16. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603]
17. Hosie, R. C. 1969. Native trees of Canada. 7th ed. Ottawa, ON: Canadian Forestry Service, Department of Fisheries and Forestry. 380 p. [3375]
18. Hosner, John F.; Minckler, Leon S. 1963. Bottomland hardwood forests of southern Illinois--regeneration and succession. Ecology. 44(1): 29-41. [3739]
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[4182] Index
Related categories for Species: Celtis occidentalis
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