Acacia melanoxylon - R. Br. ex Ait. f.
Blackwood Acacia
Other English Common Names: Blackwood
Other Common Names: blackwood
Taxonomic Status: Accepted
Related ITIS Name(s): Acacia melanoxylon R. Br. ex Ait. f. (TSN 26431)
Unique Identifier: ELEMENT_GLOBAL.2.155475
Element Code: PDFAB020M0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pea Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Fabales Fabaceae Acacia
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Acacia melanoxylon
Conservation Status
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NatureServe Status

Global Status: GNR
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States California (SNA), Hawaii (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Native of Australia, it was introduced as a forestry planting to Hawaii, New Zealand, and South Africa.

Overall Threat Impact Comments: Smith (1985) lists blackwood acacia as one of 33 alien species which should be monitored as potential threats to native ecosystems. This species is spreading vegetatively in pine plantations in Waikamoi Preserve, and has begun to escape from the plantations into adjacent drainages. The magnitude of its threat to native ecosystems is limited if its spread is exclusively vegetative. If reproduction from seed becomes common, the potential for invasiveness is considerably greater.

Short-term Trend: Increase of >10%
Short-term Trend Comments: In Hawaii, invasive in some areas; spreading vegetatively in pine plantations in Waikamoi Preserve, and has begun to escape from the plantations into adjacent drainages.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Native of Australia, it was introduced as a forestry planting to Hawaii, New Zealand, and South Africa.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States CAexotic, HIexotic

Range Map
No map available.

Ecology & Life History
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Basic Description: A medium sized tree of the legume family (Fabaceae).
Technical Description: Plants typically less than 12 tall and 1 m in diameter in Hawaii although much taller in its native range. Leaves modified as coriaceous, glabrous, and alternate phyllodes 6-12 cm long and 1-2 cm wide. Phyllodes resemble Acacia koa, but less curved. Leaves of young sprouts or seedlings bipinnately compound, with 4-10 pairs of branches, each with 15-20 leaflets. Flowers yellow, tiny, numerous, and organized into round clusters, 3-5 clusters per flowering stalk. Five petals, many threadlike stamens. Fruit a curved, twisted pod, 7-13 cm long and less than 1 cm wide with thickened borders. Seeds 4-10 per pod, shining black.
Duration: PERENNIAL, DECIDUOUS
Reproduction Comments: Blackwood acacia is a moderately fast growing species in Hawaii (Nelson and Scubert 1976, Little and Skolmen 1989). Its main and possibly only means of reproduction in Hawaii may be vegetative through root sprouting. Viable seeds have been produced in Hawaii, at least from trees used as a seed source for forestry plantings (location unknown). Blackwood acacia regenerates from seed in its native range, and copious seedling recruitment is responsible for its invasiveness in South Africa (De Zwaan, 1980).

Blackwood acacia is apparently fire-stimulated, with prolific regeneration from seed after fire (Hill 1982).

Ecology Comments: The ecology of this species in Hawaii is poorly understood. There is a plethora of literature on this species from Australia, South Africa, and New Zealand dealing with its wood qualities and use in forestry.
Habitat Comments: Native of rainforest areas in southeastern Australia, it was introduced to Hawaii as a forestry planting (Nelson and Schubert 1976). It has been planted sparingly in wet to mesic habitats (Skolmen pers. comm.), and is best adapted to cool, moist sites (Nelson and Schubert 1976). It is found in Waikamoi Preserve but not Kamakou Preserve.
Economic Attributes
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Economic Uses: Fuelwood
Management Summary
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Stewardship Overview: Blackwood acacia is a potentially invasive species in Hawaii. However, its potential is limited by its apparent lack of regeneration from seed. Massive recruitment from seed following disturbance is possible. Production of viable seed and seedling recruitment should be monitored. Until then, the most logical management program is to quarantine blackwood acacia within the pine plantations while controlling root suckers that escape from the plantation.
Management Requirements: Control of root sprouts escaping the plantations into drainages in Waikamoi should first be controlled. Then all blackwood acacia near the edges of the plantations should be treated.

Effective control methods have not been developed yet. Some preliminary studies to identify biocontrol agents in its home range have been conducted (Den Berg 1982). However, biocontrol is not feasible or warranted in Hawaii.

Monitoring Requirements: Production of seed and recruitment from seed should be monitored.

If apparently viable seed are produced, hot water treatment should be used to test germination. This consists of placing seeds in boiling water, removing the heat source, letting seed soak overnight, and then germinating. Recruitment from seed can be evaluated by uprooting young plants to determine if they are connected to long, lateral roots.

Monitoring Programs: Apparently none in Hawaii
Management Research Programs: Waikamoi staff is testing a 50% Garlon 3A solution on cut stumps.
Management Research Needs: An effective cut-surface herbicide is needed. Undiluted Garlon 3A and Roundup should be tested.

If fruiting trees are located in Waikamoi, a quick examination of the soil seed bank for the presence of viable seeds may be useful to management. Blackwood acacia seeds require scarification to germinate (De Zwaan 1978). A soil seed bank may have developed that could be stimulated by disturbance such as fire, resulting in recruitment and spread of this species.

Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: Medium/Insignificant
Rounded I-Rank: Unknown
I-Rank Reasons Summary: Currently Acacia melanoxylon has a very limited range, and is likely to spread very slowly.
Subrank I - Ecological Impact: Medium/Low
Subrank II - Current Distribution/Abundance: Low/Insignificant
Subrank III - Trend in Distribution/Abundance: Medium/Insignificant
Subrank IV - Management Difficulty: Unknown
I-Rank Review Date: 19Feb2004
Evaluator: Fellows, M.
Native anywhere in the U.S?
Native Range: Australia (Weber 2003)

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: (Kartesz 1999)

S-2. Present in conservation areas or other native species habitat? Yes
Comments: (Weber 2003)

Subrank I - Ecological Impact: Medium/Low

1. Impact on Ecosystem Processes and System-wide Parameters:High/Low significance
Comments: large litter deposits, changes soil nitrogen (Weber 2003)

2. Impact on Ecological Community Structure:Moderate significance
Comments: dense thickets (Weber 2003)

3. Impact on Ecological Community Composition:Low significance/Insignificant
Comments: limited if spread is only via vegetative means (Tunison 1991)

4. Impact on Individual Native Plant or Animal Species:Medium significance/Insignificant
Comments: inferred -not a significant enough part of a community to have substantial impacts; many native Acacia in California (Hickman 1993)

5. Conservation Significance of the Communities and Native Species Threatened:Low significance
Comments: inferred -not a significant enough part of a community to severely affect common systems, however, in rare scrub sites it could be a problem

Subrank II. Current Distribution and Abundance: Low/Insignificant

6. Current Range Size in Nation:Low significance
Comments: (Kartesz 1999)

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:Low significance/Insignificant
Comments: uncommon on disturbed areas (Hickman 1993)

8. Proportion of Nation's Biogeographic Units Invaded:Low significance
Comments: comparison of Kartesz (1999) with TNC (2001); (Hickman 1993)

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Moderate significance
Comments: Forest edges, gaps, grass and heathlands, scrubland, riparian habitats (Weber 2003)

Subrank III. Trend in Distribution and Abundance: Medium/Insignificant

10. Current Trend in Total Range within Nation:Unknown

11. Proportion of Potential Range Currently Occupied:High/Low significance
Comments: inferred - not in a huge area in US, but significant problem in other Mediterannean climates, so could expand in US

12. Long-distance Dispersal Potential within Nation:Unknown

13. Local Range Expansion or Change in Abundance:Low significance
Comments: spreading vegetatively (=slowly) in HI (Tunison 1991)

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Low significance
Comments: recruitment after disturbance required for infestation (Tunison 1991)

15. Similar Habitats Invaded Elsewhere:High/Low significance
Comments: Southern Europe, Southern Africa, Reported in Azores, Southern South America, Central Europe (Weber 2003); much more severe problem in South Africa, relatively benign in US (Tunison 1991)

16. Reproductive Characteristics:Medium/Low significance
Comments: vigourous seed bank - South Africa (Weber 2003); frequently suckering from roots (Weber 2003); viable seeds not often in Hawaii (Tunison 1991)

Subrank IV. General Management Difficulty: Unknown

17. General Management Difficulty:Medium/Low significance
Comments: hand-remove, cut & treat larger plants (Weber 2003); hard to remove resprouts - effective methods not yet developed (Tunison 1991)

18. Minimum Time Commitment:High/Low significance
Comments: vigourous seed bank - South Africa (Weber 2003)

19. Impacts of Management on Native Species:Unknown

20. Accessibility of Invaded Areas:Unknown
Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 17Jun1991
NatureServe Conservation Status Factors Author: TIM TUNISON, PRO
Management Information Edition Date: 17Jun1991
Management Information Edition Author: TIM TUNISON, PRO
Element Ecology & Life History Edition Date: 17Jun1991
Element Ecology & Life History Author(s): TIM TUNISON, PRO

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • De Zwaan, J. G. 1980. Is a seedless blackwood tree a possibility? South African Journal of Forestry 113:59-61.

  • De Zwaan, J. G. [1978]. The effects of hot-water-treatment and stratification on germination of blackwood (Acacia melanolylon) seed. South African Journal of Forestry. 105:40-42.

  • Den Berg van, M. A. 1982. Coleoptera attacking Acacia dealbata Link., Acacia decurrens Willd., Acacia longifolia (Andr.), Willd., Acacia mearnsii De Wild., and Acacia melanoxylon R. Br. in Australia. Phytophylactica 14(2):51-55.

  • Hickman, J. C., ed. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 1400 pp.

  • Hill, R. S. 1982c. Rainforest fire in western Tasmania. Australian Journal of Botany 30:583-589.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Smith, C. W. 1985. Impact of alien plants on Hawaii's native biota. pp. 180-250. in C. P. Stone and J. M. Scott (eds.). Hawaii's terrestrial ecosystems: preservation and management. Univ. Hawaii Coop. Natl. Park Resour. Studies Unit, University of Hawaii Press. 584 pp.

  • The Nature Conservancy. 2001. Map: TNC Ecoregions of the United States. Modification of Bailey Ecoregions. Online . Accessed May 2003.

  • Tunison, T. 1991. Element Stewardship Abstract: Acacia melanoxylon. Unpublished report for The Nature Conservancy. Arlington, Virginia. 4 pgs.

  • Weber, E. 2003. Invasive plant species of the world: a reference guide to environmental weeds. CABI Publishing, Cambridge, Massachusetts. 548 pp.

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