Hackberry (Celtis occidentalis)

Present distribution

Scientific name:	Celtis occidentalis (L.)
Common name(s):	hackberry

This weed is not known to be naturalised in Victoria

Habitat:

Hardwood stands, prairie conditions, dense shade (UFEA 2009). Rich moist sites along stream banks or on flood plains; alkaline or acid conditions, full sun and wind, frost injury, requires at least 14 inches annual rain (USDA 2009). Low woods along streams and in drier upland slopes (MBG 2009). Tolerate acid, alkaline soil. Very soil adaptable (UCONN 2009). Drought resistant, flooding (UFEA 2009). Alluvial soils (USDA 2009).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:
Pasture irrigation

Ecological Vegetation Divisions
Swampy scrub; lowland forest; foothills forest; forby forest; damp forest; riparian; wet forest; rainforest; granitic hillslopes; alluvial plains grassland; riverine woodland/forest

Colours indicate possibility of Celtis occidentalis infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	40-60 feet (MBG 2009). Trees or shrubs (eFloras 2009). It can become a pest along riverbanks and channels in some countries (Burnie et al. 2009). High nuisance value. People and/or vehicles access with difficulty.	mh	m
2. Reduce tourism?	Seeds can pose clean up problems if trees are sited near side walks or patios, however” (MBG 2009). Deep rooting species up to 6m deep (UFEA 2009). Bird droppings are often found underneath the tree in early autumn due to the bird’s over consumption of the ripened fruits (OSU 2009). Fast growing, very large tree (OSU 2009); It can become a pest along riverbanks and channels in some countries (Burnie et al. 1997). Some recreational uses affected.	mh	mh
3. Injurious to people?	No spines, burrs, toxins (UFEA 2009; OSU 2009). No effect, no prickles, no injuries.	l	mh
4. Damage to cultural sites?	“Seeds can pose clean up problems if trees are sited near side walks or patios, however” (MBG 2009). Deep rooting species up to 6m deep (UFEA 2009). Bird droppings are often found underneath the tree in early autumn due to the bird’s over consumption of the ripened fruits (OSU 2009). Moderate structural effect.	mh	mh
Abiotic
5. Impact flow?	“In rich moist soil along streams (eFloras 2009). Roots, or litter falling into the stream could reduce flow. Minor impact on surface or subsurface flow either by roots or free floating aquatics.	ml	m
6. Impact water quality?	“In rich moist soil along streams (eFloras 2009); Fast growing, very large tree (OSU 2009); Used as shade tree (OSU 2009) therefore is likely to reduce light levels for streams/ smaller rivers. It can become a pest along riverbanks and channels in some countries (Burnie et al. 1997). Noticeable but minor effects in either dissolved 0₂or light levels.	ml	mh
7. Increase soil erosion?	Used for erosion control (OSU 2009). Low probability of large scale soil movement; or decreases the probability of soil erosion.	l	mh
8. Reduce biomass?	Fast growing, very large tree (OSU 2009). Trees or shrubs (eFloras 2009). It can become a pest along riverbanks and channels in some countries (Burnie et al. 1997). Direct replacement of biomass by invader.	ml	mh
9. Change fire regime?	Fire resistance: No/ fire tolerance: high. (NRCS 2009). Conflicting information.	m	l
Community Habitat
10. Impact on composition (a) high value EVC	EVC = Cool temperate rainforest (E/V); CMA = Goulburn broken; Bioregion = Highlands Northern Fall; VH CLIMATE potential. Hardwood stands, dense shade (UFEA 2009). Low woods along streams & in drier upland slopes (MBG 2009). “It can become a pest along river banks and channels in some countries (Burnie et al. 1997). Minor displacement of some dominant or indicator spp. within any one strata/ layer (eg. Ground cover, forbs, shrubs & trees).	ml	m
(b) medium value EVC	EVC = Riparian Scrub/ Swampy Riparian Woodland (D); CMA =Corangamite; Bioregion = Otway plain; VH CLIMATE potential. Rich moist sites along stream banks or on flood plains (USDA 2009). Low woods along streams & in drier upland slopes (MBG 2009). “It can become a pest along river banks and channels in some countries (Burnie et al. 1997). Major displacement of some dominant spp. within a strata/layer (or some dominant spp. within different layers).	mh	mh
(c) low value EVC	EVC = Riparian scrub (LC); CMA = Glenelg Hopkins; Bioregion = Greater Grampians; VH CLIMATE potential. Rich moist sites along stream banks or on flood plains (USDA 2009). Low woods along streams & in drier upland slopes (MBG 2009). “It can become a pest along river banks and channels in some countries (Burnie et al. 1997). Major displacement of some dominant spp. within a strata/layer (or some dominant spp. within different layers).	mh	mh
11. Impact on structure?	It can become a pest along riverbanks and channels in some countries (Burnie et al. 2009). Fast growing, very large tree (OSU 2009). (In the US) “Hackberry grows best on moist alluvial soils, and occurs only as scattered trees mixed with other hardwoods (USDA 2009). Minor effect on 20-60% of the floral strata.	ml	m
12. Effect on threatened flora?	It can become a pest along riverbanks and channels in some countries (Burnie et al. 2009). No information on effects on threatened flora. Probably reduces population sizes of native flora growing in riparian zones.	m	m
Fauna
13. Effect on threatened fauna?	Palatable; Toxicity: none (NCRS 2009). Attracts birds, butterflies, fruit edible, fruits are attractive to a wide variety of wildlife (MBG 2009). Birds use adult trees as nesting sites (OSU 2009). It can become a pest along riverbanks and channels in some countries (Burnie et al. 1997). No mention of effects on threatened fauna. Minor effects on threatened spp.; minor hazard or reduction in habitat/food/ shelter.	ml	m
14. Effect on non-threatened fauna?	Palatable; Toxicity: none (NCRS 2009). Attracts birds, butterflies, fruit edible, fruits are attractive to a wide variety of wildlife (MBG 2009). Birds use adult trees as nesting sites (OSU 2009). It can become a pest along riverbanks and channels in some countries (Burnie et al. 1997). Minor effects on fauna spp.; minor hazard or reduction in habitat/food/ shelter.	ml	mh
15. Benefits fauna?	Attracts birds, butterflies, fruit edible, fruits are attractive to a wide variety of wildlife (MBG 2009). Birds use adult trees as nesting sites (OSU 2009).	m	mh
16. Injurious to fauna?	No spines, burrs thorns (OSU 2009) and no toxins mentioned in literature. No effect.	l	mh
Pest Animal
17. Food source to pests?	Attracts birds, butterflies; fruit edible; fruits are attractive to a wide variety of wildlife (MBG 2009). Likely to be a food source for foxes, rabbits and blackbirds. Berry load is likely to be heavy (see invasiveness no. 10 – but not enough info). Supplies food serious pest (eg. rabbits and foxes), but at low levels (eg. foliage).	mh	mh
18. Provides harbour?	“Young stands also provide shelter for game birds, rabbits, and deer” (OSU 2009). Capacity to harbour rabbits or foxes at low densities or as overnight cover.	mh	mh
Agriculture
19. Impact yield?	Environmental weed, not reported as an agricultural weed. Palatable browse animal: medium (NRCS 2009). Not reported as a crop weed. Little or negligible affect on quantity of yield.	l	mh
20. Impact quality?	Environmental weed, not reported as an agricultural weed. Not reported as a crop weed. It can become a pest along riverbanks and channels in some countries (Burnie et al. 1997). May restrict access to water sources for livestock.	ml	m
21. Affect land value?	Environmental weed, not reported as an agricultural weed. Not reported as a crop weed. Unlikely to affect land value. Little or none.	l	m
22. Change land use?	Environmental weed, not reported as an agricultural weed. Not reported as a crop weed. Little or no change	l	m
23. Increase harvest costs?	40-60 feet (MBG 2009). Trees or shrubs (eFloras 2009); Fast growing, very large tree (OSU 2009). It can become a pest along riverbanks and channels in some countries (Burnie et al. 1997). May restrict access to waterways for livestock and need to be controlled, control would increase harvest costs. Minor increase in cost of harvesting – eg slightly more time or labour is required.	ml	m
24. Disease host/vector?	Witches broom, powdery mildew, leaf spot and root rot, lacebugs and scale (MBG 2009). Provides host to minor (or common) pests, or diseases.	ml	mh

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	Germination of hackberry is epigeal (1). In eastern Iowa, hackberry seedlings become established in existing hardwood stands but rarely in old fields; Illinois – prairie conditions, Pennsylvania: dense shade (UFEA 2009). Requires natural seasonal disturbances such as seasonal rainfall, spring/summer temperatures for germination.	mh	mh
2. Establishment requirements?	Hackberry is commonly found on rich, moist sites along stream banks or on flood plains, but will perform well under more adverse conditions - It tolerates alkaline or acid soil conditions, full sun, and wind. New growth is subject to spring frost injury. Common hackberry requires at least 14 inches annual precipitation. (USDA 2009). Early growth of hackberry varies greatly within its range and even on different sites in a single locality (UFEA 2009). Pennsylvania germinates under dense shade (UFEA 2009). Can establish under moderate canopy/litter cover	mh	mh
3. How much disturbance is required?	“Occurs state-wide in low woods along streams and in drier upland slopes” (MBG 2009). Pennsylvania: germinates under dense shade (UFEA 2009). Establishes in relatively intact or only minor disturbed natural ecosystems (eg. wetlands, riparian, riverine, grasslands, open woodlands); in vigorously growing crops or in well-established pastures.	mh	mh
Growth/Competitive
4. Life form?	Small to medium sized tree (UFEA 2009). Other.	l	mh
5. Allelopathic properties?	Known allelopath: No (NRCS 2009).	l	m
6. Tolerates herb pressure?	Grazing should be controlled during establishment (UCONN 2009). Sprouts develop from stumps of small trees but rarely from those of large ones (UFEA 2009). Some degree of tolerance as it resprouts (NRCS 2009).	m	m
7. Normal growth rate?	Fast growth rate (UCONN 2009). “On good bottom-land soils it grows fast and may live to 20 years” (UFEA 2009). Rapid growth rate that will exceed most other species of the same life form.	h	mh
8. Stress tolerance to frost, drought, w/logg, sal. etc?	Prefers rich soil, very soil, adaptable, tolerant of most conditions, wind tolerant, full sun, urban tolerant (UCONN 2009). It tolerates alkaline or acid soil conditions, full sun, and wind. New growth is subject to spring frost injury. Common hackberry requires at least 14 inches annual precipitation. (USDA 2009). Hackberry is planted as a street tree in midwest cities because of its tolerance to a wide range of soil and moisture conditions. (UFEA 2009). Hackberry is drought resistant and has survived extremely dry periods in the Great Plains (UFEA 2009). Occasional trees have lived 3 years under flooded conditions..moderate to shade (UFEA 2009). Highly tolerant of at least two of drought, frost, fire, waterlogging, and salinity, and may be tolerant of another. Susceptible to at least one.	mh	mh
Reproduction
9. Reproductive system	Polygamo-monoecious (UFEA 2009). Sexual (self and cross-pollination).	ml	mh
10. Number of propagules produced?	Abundant fruit crop….Seeds can pose clean up problems if trees are sited near sidewalks or patios (MBG 2009), however(UFEA 2009). Celtis (C. australis) produces thousands of fleshy fruits (Agnote 2009). Thousands of small, orange berries are produced (C. sinensis) (NRW 2009). Estimate above 2000.	h	m
11. Propagule longevity?	In an Indiana study, 34 percent of the hackberry seed stored 1 year in the leaf litter germinated and 20 percent of the seed germinated after being stored 2 winters (UFEA 2009). Greater than 25% of seeds survive 5 years, or vegetatively reproduces.	l	m
12. Reproductive period?	“On good bottom-land soils it grows fast and may live to 20 years…but 150-200 years on poorer sites” (UFEA 2009). Mature plant produces viable propagules for 10 years or more, or species forms self-sustaining monocultures.	h	h
13. Time to reproductive maturity?	No information.	m	l
Dispersal
14. Number of mechanisms?	The cherrylike fruits often hang on the trees throughout the winter providing many birds with food…but some may be dispersed by water (UFEA 2008). Bird dispersed (MBG 2009). Bird dispersed.	h	h
15. How far do they disperse?	Water and bird dispersed (UFEA 2009). Likely that one seed will be dispersed greater than 1km.	h	mh

References

Burnie G, Forester S, Grieg D, Guest S, Harmony M, Hobley S, Hackson G, Lavarack P, Ledgett M, McDonald R, Macoboy S, Molyneux B, Moodie D, Moore J, Newman D, North T, Pienaar K, Purdy G, Silk J, Ryan S, Schien G (1997) Botanica Random House. Milsons Point, NSW.

eFloras (2009) eFloras. Flora of North America. Available at http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500334 (verified 10/05/2009).

MBG (2009) Missouri Botanical Garden. Available at http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=A858 (verified 10/05/2009).

NRCS (2009). Natural Resources Conservation Service. Available at http://plants.usda.gov/java/charProfile?symbol=CEOC (verified 10/05/09).

OSU (2009). Ohio state university. Available at http://hcs.osu.edu/hcs/TMI/Plantlist/ce_talis.html (verified 10/05/2009).

PNTN (2009) Plant Net. Available at http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Celtis~occidentalis (verified 10/05/2009).

UCONN (2009) University of Connecticut. Plant database. Available at http://www.hort.uconn.edu/plants/c/celocc/celocc1.html (verified 10/05/2009).

UFEA (2009) US Forest Service – Eastern Area. Available at http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/celtis/occidentalis.htm (verified
10/05/2009).

UNFL (2009) University Florida Forest Service. Available at http://hort.ufl.edu/trees/CELAUSA.pdf (verified 10/05/2009).

USDA (2009) US department of Agriculture. Available at http://plants.usda.gov/factsheet/pdf/fs_ceoc.pdf (verified 10/05/2009).

Global present distribution data references

Australian Plant Name Index (APNI) http://www.cpbr.gov.au/cgi-bin/apni (26/03/2009).

Australian National Herbarium (ANH) (2008) Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, Available at http://www.anbg.gov.au/avh/ (verified 17/02/2009).

Department of the Environment and Heritage (Commonwealth of Australia). (1993 – On-going) Australian Plant Name Index (APNI)
http://www.cpbr.gov.au/apni/index.html (verified 07/05/2009).

Global Biodiversity Information Facility (GBIF) (2008) Global biodiversity information facility, Available at http://www.gbif.org/ (verified 17/02/2009).

Integrated Taxonomic Information System. (2009) Available at http://www.itis.gov/ (verified 07/05/2009).

United States Department of Agriculture. Agricultural Research Service, National Genetic Resources Program. Germplasm Resources Information Network - (GRIN) [Online Database]. Taxonomy Query. (2009) Available at http://www.ars-grin.gov/cgi-bin/npgs/html/taxgenform.pl (verified 26/03/2009).

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