Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Acacia mearnsii; Australian acacia

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

1

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

y

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

n

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

n

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

y

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

y

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

y

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

y

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

y

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

n

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

y

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

y

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

n

6.04

Self-compatible or apomictic

y=1, n=-1

y

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

3

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

7.05

Propagules water dispersed

y=1, n=-1

y

7.06

Propagules bird dispersed

y=1, n=-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

7.08

Propagules survive passage through the gut

y=1, n=-1

y

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

n

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

y

8.03

Well controlled by herbicides

y=-1, n=1

y

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

y

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

15

Source

Notes

1.01

no evidence

1.02

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

A. mearnsii is an aggressive colonizer and has become a weed in some parts of southern Africa where fires occur (Boucher, 1980).

1.03

no evidence

2.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

Review of Natural Distribution
A. mearnsii is a native wattle of southeastern Australia. It extends through southern New South Wales and southern Victoria to southeastern South Australia and Tasmania. The northern limit is west of Sydney
Natural latitude range
Approximate limits north to south: 33S to 42S

2.02

2.03

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

" A. mearnsii occurs across an altitudinal range of approximately 1050 m, from coastal locations just above sea level to 1070 m elevation on Mt Gladstone, west of Cooma, New South Wales."

2.04

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

Review of Natural Distribution
A. mearnsii is a native wattle of southeastern Australia. It extends through southern New South Wales and southern Victoria to southeastern South Australia and Tasmania. The northern limit is west of Sydney
Natural latitude range
Approximate limits north to south: 33S to 42S

2.05

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

Location of introductions
A. mearnsii is widely cultivated in a number of countries throughout the world. Principal growing areas include Brazil with over 200,000 ha of plantation (Higa and Resende, 1994), South Africa with 160,000 ha (Boucher, 1980), down from 325,000 in the halcyon days of tannin production in the 1960s (Wiersum, 1991), with 30,000 ha in East Africa (Zimbabwe, Kenya, Tanzania, Rwanda, Burundi), India with 20,000 ha and Indonesia with 15,000 ha of plantations (Wiersum, 1991). Black wattle is grown extensively in China for vegetable tannin production. When surveyed in 1987 the total area of plantations was 10,433 ha. Ho and Fang (1997) discuss the distribution of black wattle plantations in China. In addition there are extensive, largely unrecorded plantings in agroforestry systems in many countries.

3.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

A. mearnsii is an aggressive colonizer and has become a weed in some parts of southern Africa where fires occur (Boucher, 1980).

3.02

no evidence

3.03

(1)Bacon, P., P.J. Terry, N. Waltham, & P.Castro S. (1997) An Electronic Atlas of World Weed and Invasive Plants. Version 1.0, 1997. A database based on the original work "A Geographical Atlas of World Weeds" by Holm et al 1979. (2)http://www.hear.org/pier/species/acacia_mearnsii.htm

(1)A. mearnsii was listed as a 'common' weed in South Africa (2)Prolific seeder, closes in pastures and displaces natives in natural areas." (Mootka et al., 2002) [Motooka, P., L. Castro, D. Nelson, G. Nagai and L. Ching . 2002. Weeds of pastures and natural areas of Hawaii and their management, UHCTAHR, Honolulu]

3.04

(1)http://www.npb.co.za/AlienCategories.htm (2)http://www.scarborough.org.za/invaders.asp (3)http://www.botany.hawaii.edu/faculty/cw_smith/aca_mea.htm (4)http://www.hear.org/pier/species/acacia_mearnsii.htm

(1)CATEGORY B invader of S. Africa (may be grown under controled conditions) (2)S. africa (3)This noxious, evergreen tree often reaches 20 m in height...it generates numerous suckers resulting in monotypic thickets..The major infestation is at Kula, Maui. (4)Prolific seeder, closes in pastures and displaces natives in natural areas." (Mootka et al., 2002) [Motooka, P., L. Castro, D. Nelson, G. Nagai and L. Ching . 2002. Weeds of pastures and natural areas of Hawaii and their management, UHCTAHR, Honolulu]

3.05

Weed Control Manual 2000. Meister Publishing Co., Salem, MA.

Acacia rigidula, Acacia tortuosa and Acacia farnesiana are listed under weeds of pastures and rangeland. Tricopyr is the suggested herbicide for their control.

4.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

no description of these traits

4.02

Schumann, A. W.; Little, K. M.; Eccles, N. S. (1995) Suppression of seed germination and early seedling growth by plantation harvest residues. South African Journal of Plant and Soil, 1995, Vol.12, No.4, pp.170-172, 4 ref.

AB: The role of forestry plantation residues (leaf and branch) in suppressing the establishment of four weed species (Conyza sumatrensis, Trifolium spp., Echinochloa utilis and Lactica sativa [Lactuca sativa ; lettuces?]) was investigated under greenhouse conditions. Of the three residue types used, Pinus patula residues were found to have the greatest suppressive effects, followed by Eucalyptus grandis and then Acacia mearnsii . Medium-grade residue was found to be more effective than either the coarse or fine grades, and positioning the weed seeds below the mulch resulted in greater suppression than when placed above it. Water extracts from the three residues also resulted in significant suppression of weed establishment, suggesting an allelopathic effect. Finally, suppression of the dicotyledonous species was generally greater than suppression of the grasses studied. []lab study of unknown relevance in field]

4.03

no evidence

4.04

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.hort.purdue.edu/newcrop/duke_energy/Acacia_mearnsii.html

(1)The leaves (phyllodes) of A. mearnsii have a high protein content (15%), but palatability trials with sheep showed milled leaves to be unpalatable on their own and were only acceptable when mixed with other feedstocks (Goodriche, 1978). Goodriche considered that digestibility was probably affected by the high tannin content in the leaves and twigs (5.7%, dry weight). Considered to be inferior stock feed in Japan but has been fed to cattle in Hawaii during drought periods. (2)Forage not listed as a potential use.

4.05

no evidence

4.06

(1) Donnelly, D. (1986) Rayieria sp. (Heteroptera: Miridae): host specificity, conflicting interests, and rejection as a biological control agent against the weed Acacia longifolia (Andr.) Willd. in South Africa. Journal of the Entomological Society of Southern Africa, 1986, Vol.49, No.2, pp.183-191, 11 ref.
(2) Vulcano, M. A.; Pereira, F. S. (1978) The genus Oncideres Serville 1835 (Coleoptera, Lamiidae) in southern Brazil and adjacent countries, a serious pest of orchards and silviculture. [FT: O genero Oncideres Serville 1835. (Coleoptera, Lamiidae) do Sul do Brasil e paises limitrofes, seria praga dos pomares e da silvicultura.] Studia Entomologica, 1978, Vol.20, No.1/4, pp.177-220, 4 pp. ref.

(1) AB: An undescribed species of Rayieria was considered as a potential biological control agent against Acacia longifolia in South Africa. The mirid is very destructive to the weed in Australia, and was introduced into South Africa for host specificity studies. Feeding, and oviposition resulting in viable offspring, were restricted to Australian species of Acacia tested. Two of these, A. mearnsii and A. melanoxylon, are commercially important in South Africa although they are also invasive weeds. Release of the mirid was therefore not recommended.
(2) AB: In Rio Grande do Sul, Brazil, heavy damage is caused to many fruit and other trees, especially Acacia mearnsii (decurrens mollissima), by Oncideres spp., the adults of which girdle twigs and branches to provide dry wood in which the larvae can develop. A key is presented to the adults of the species of this genus occurring in southern Brazil and adjacent territories, together with notes on their morphology, distribution and food-plants. The plants atta

4.07

no evidence

4.08

Pieterse, P. J.; Boucher, C. (1997 ) Is burning a standing population of invasive legumes a viable control method? Effects of a wildfire on an Acacia mearnsii population. Southern African Forestry Journal, 1997, No.180, pp.15-21, 32 ref.

AB: Acacia mearnsii is an important invasive plant in most of the higher rainfall areas of South Africa. The production of long-lived water-impermeable seeds results in the establishment of large soil-stored seed banks. One way of controlling these seed banks is by felling the plants and burning them to destroy or to stimulate seeds to germinate, so that the resulting seedlings may be controlled. In order to save costs, the hypothesis that the plant population can be burned without felling beforehand was investigated. A wildfire that swept through a standing population of A. mearnsii plants at a site between the northern shore of the Theewaterskloof Dam and the Hottentots Holland Mountains, in March 1989, provided an opportunity to investigate fire effects on the population. The mortality of the pre-fire population, the subsequent establishment of seedlings, mortality of seedlings and the spread of the population after the fire were investigated, based on post-fire measurements made in December 1989 and 1990

4.09

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"A. mearnsii is a light-demanding species with rapid early stem growth. "; "The species is intolerant of weed competition when young and plantations must be kept clean until canopy closes (Luyt IE, Mullin LJ, Gwaze DP, 1987. Black wattle (Acacia mearnsii) in Zimbabwe. ACIAR-Proceedings,-Australian-Centre-for-International-Agricultural-Research. 1987, No. 16, 128-131; In Australian acacias in developing countries. Proceedings of an international workshop, Gympie, Qld., Australia, 4-7 August 1986 [edited by Turnbull, J.W.]; 3 ref.)."

4.1

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.hort.purdue.edu/newcrop/duke_energy/Acacia_mearnsii.html

(1)Soil and physiography
A. mearnsii occurs across a broad spectrum of sites, but reaches its best development on easterly and southerly aspects of low hills in coastal lowlands and adjacent lower slopes of the tablelands and ranges.
It has been recorded on basalt, dolerite, granite and sandstone but is common on soils derived from metamorphic shales and slates. The soils are mainly loams, sandy loams, and deep forest podzols of moderate to low fertility. The best soils for A. mearnsii are moist, relatively deep, light-textured, and well-drained although it is often found on moderately heavy soils and occasionally on shallow soils. The soils are usually acidic, pH 5-6.5. It is not common on poorly-drained or very infertile sites.
Descriptors
- Soil texture: light; medium
- Soil drainage: free
- Soil reaction: acid
- Special soil tolerances:
- Soil types: alluvial soils; podzols; sandy soils (2)Thrives on poor, dry soils but favors deeper, moister,
more fertile soils.in Australia, black wattle ma

4.11

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"A large shrub or small tree, typically in the height range 5-15 m but at times reaching 20 m with a breast height diameter up to 45 cm but normally in the range of 10-35 cm. "

4.12

(1)http://www.botany.hawaii.edu/faculty/cw_smith/aca_mea.htm (2)http://groups.msn.com/LeeuwkloofValley/invasiveplants.msnw?pgmarket=en-za

(1)it generates numerous suckers resulting in monotypic thickets (2)form impenatrable thickets

5.01

terretrial

5.02

tree; Mimosaceae

5.03

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"A fast-growing, nitrogen-fixing tree "

5.04

tree

6.01

no evidence

6.02

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"Seed has a hard seed coat when fully ripened and retains viability well in storage. "

6.03

no evidence

6.04

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

A. mearnsii is regarded as an outcrossing species with partial self-compatibility. Estimates of out-crossing rates in this species are variable and range from 48 to 100% (see review in Raymond CA, 1997. Flowering biology, genetics and breeding. In: Brown AG, Ho CK, eds. Black Wattle and its Utilisation. Canberra, Australia: Rural Industries Research and Development Corporation, 18-27.).

6.05

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

The flowers are mainly insect pollinated, with honey bees considered the most important pollinators due to their methodical foraging (Moncur et al., 1991; Grant et al., 1994).

6.06

no evidence (coppice at stump, but not reproduction)

6.07

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

Trees start to flower when about 2 years old, but appreciable quantities of seed are seldom produced in plantations before the fifth or sixth year (Sherry SP, 1971. The Black Wattle (Acacia mearnsii De Wild.). 1971. pp. xix + 402 + 24 plates. [12 pp. of ref.]. University of Natal Press, Pietermaritzburg.).

7.01

Henderson, L. (1989) Invasive alien woody plants of Natal and the north-eastern Orange Free State. Bothalia, 1989, Vol.19, No.2, pp.237-261, 36 ref.

AB: A survey of the frequency and abundance of invasive alien woody plants along roadsides and at watercourse crossings yielded 130 species, of which the most prominent species (in order of prominence) in roadside and veld habitats were Chromolaena odorata [Eupatorium odoratum], Solanum mauritianum, Psidium guajava, Rubus spp., Acacia mearnsii and Lantana camara. The most prominent species (in order of prominence) in streambank habitats were Acacia dealbata, A. mearnsii and Salix babylonica. The greatest intensity of invasion was recorded in the Natal midlands and the coastal belt of S. Natal, including the metropolitan areas of Pietermaritzburg and Durban. There was relatively little invasion in the NE lowlands of Natal but the potential for expansion is great. Little invasion was recorded in NE Orange Free State except along some watercourses.

7.02

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"A. mearnsii is widely cultivated in a number of countries throughout the world. Principal growing areas include Brazil with over 200,000 ha of plantation (Higa and Resende, 1994), South Africa with 160,000 ha (Boucher, 1980), down from 325,000 in the halcyon days of tannin production in the 1960s (Wiersum, 1991), with 30,000 ha in East Africa (Zimbabwe, Kenya, Tanzania, Rwanda, Burundi), India with 20,000 ha and Indonesia with 15,000 ha of plantations (Wiersum, 1991). Black wattle is grown extensively in China for vegetable tannin production. When surveyed in 1987 the total area of plantations was 10,433 ha. Ho and Fang (1997) discuss the distribution of black wattle plantations in China. In addition there are extensive, largely unrecorded plantings in agroforestry systems in many countries."

7.03

no evidence

7.04

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

The pods are more or less straight but often constricted between the seeds, dark brown to blackish when ripe, finely hairy, 5-15 cm long by 0.4-0.8 cm wide. There are 7 (1-14) seeds, longitudinal in the pod, black, smooth, ovoid, 3-5 mm long by 2-3.5 mm wide with a short, creamy coloured, terminal aril.

7.05

(1)http://groups.msn.com/LeeuwkloofValley/invasiveplants.msnw?pgmarket=en-za (2)Henderson, L. (1989) Invasive alien woody plants of Natal and the north-eastern Orange Free State. Bothalia, 1989, Vol.19, No.2, pp.237-261, 36 ref.

(1)Water carries the seeds long distances (2)in streambank habitats

7.06

http://groups.msn.com/LeeuwkloofValley/invasiveplants.msnw?pgmarket=en-za

Birds, baboons also disperse seeds [uncommon??]

7.07

no evidence [no means of attachment]

7.08

Martins-Corder, M. P.; Borges, R. Z.; Borges Júnior, N. (1999) Photoperiodism and dormancy breaking in black wattle (Acacia mearnsii de Wild.) [FT: Fotoperiodismo e quebra de dormência em sementes de acácia-negra (Acacia mearnsii de Wild.). Ciência Florestal, 1999, Vol.9, No.1, pp.71-77, 14 ref.

AB: "The seeds of the species have hard seed coats and exhibit dormancy."

8.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"There are about 71,900 viable seeds/kg (Doran and Turnbull 1997)"; "Seed yields per tree in a 10-year-old seed production area in Brazil averaged 0.7 kg (Stein and Tonietto, 1997). " A. mearnsii is a light-demanding species with rapid early stem growth. Growth rates of up to 3 m/year are reached after 3-5 years (Wiersum, 1991). It is a relatively short-lived species with a life-span of 10-20 years.; A large shrub or small tree, typically in the height range 5-15 m but at times reaching 20 m with a breast height diameter up to 45 cm but normally in the range of 10-35 cm." [71900x0.7=50330seeds/tree; if a ten year tree have a canopy area less than 50.33 square meter then yes. It is about 4 meter in radius. Based on the tree form on the picture, a 10m high tree should have a canopy more than 5 m in radius.]

8.02

http://www.hort.purdue.edu/newcrop/duke_energy/Acacia_mearnsii.html

Seeds retain their viability for several years.

8.03

Little, K. M. (2002) Acacia mearnsii sensitivity to the application of pre-emergent herbicides applied at planting. Southern African Forestry Journal, 2002, No.193, pp.15-23, 30 ref.
(2) Ethokem - thirteen years on its use on tropical and temperature crops. International Sugar Journal, 1993, Vol.95, No.1135, pp.270-272

(1) AB: Five pre-emergent herbicides were applied either on their own or in various combinations to commercially planted Acacia mearnsii De Wild. seedlings in the KwaZulu-Natal Midlands. Acacia mearnsii growth responses to the protected or unprotected application of these herbicides were compared to a weedfree and weedy control. Compared to the weedfree control, suppression from weed competition only caused a significant reduction in tree growth from 92 days after planting, by which stage most of the residual capabilities of the herbicides tested had been reduced. The herbicides which did give good control of both grasses and volunteer wattle regeneration relative to the weedy treatment were oxyfluorfen alone, or when combined with thiazopyr or thiazopyr+metazachlor. When applied as an unprotected spray, only the herbicide combinations of simazine/terbuthylazine and metazachlor did not cause a significant reduction in tree growth. Although only significant at p <0,1 the herbicides of oxyfluorfen and glyphosa

8.04

(1) Pieterse, P. J.; Boucher, C. (1997) Is burning a standing population of invasive legumes a viable control method? Effects of a wildfire on an Acacia mearnsii population. Southern African Forestry Journal, 1997, No.180, pp.15-21, 32 ref.
(2)http://www.botany.hawaii.edu/faculty/cw_smith/aca_mea.htm

(1) . It was found that in the December after the fire the above-ground population (stem density) increased by a factor of ca. 21.8 due to coppicing of young plants, and that the mean distance of spread from the edge of an infestation was ca. 20 m. About 90% of seedlings that established died within 2 years. Due to the growth of the population, and the difficulty of controlling coppicing plants, a standing burn is not, therefore, recommended as a control measure for A. mearnsii . ung (< 3 yr) " (2)The species resprouts by basal shoots following fire, thereby generally intensifying the infestation.

8.05

no evidence