Invasive Species Compendium

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Datasheet

Acacia melanoxylon
(Australian blackwood)

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Datasheet

Acacia melanoxylon (Australian blackwood)

Summary

  • Last modified
  • 16 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Acacia melanoxylon
  • Preferred Common Name
  • Australian blackwood
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • A. melanoxylon is a fast growing nitrogen fixing species, able to grow on a variety of soils, prolifically produces seeds with extreme longevity and high germinability from an early age and is also able to spread from r...

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Pictures

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PictureTitleCaptionCopyright
Australia.
TitleForest tree
CaptionAustralia.
CopyrightSuzette Searle/CSIRO Forestry and Forest Products
Australia.
Forest treeAustralia.Suzette Searle/CSIRO Forestry and Forest Products
Australia.
TitleWoodland tree
CaptionAustralia.
CopyrightMaurice McDonald/CSIRO Forestry & Forest Products
Australia.
Woodland treeAustralia.Maurice McDonald/CSIRO Forestry & Forest Products
Zimbabwe.
Title10-year-old plantation
CaptionZimbabwe.
CopyrightDoug Boland/CSIRO Forestry and Forest Products
Zimbabwe.
10-year-old plantationZimbabwe.Doug Boland/CSIRO Forestry and Forest Products
TitleBark
Caption
CopyrightSuzette Searle/CSIRO Forestry and Forest Products
BarkSuzette Searle/CSIRO Forestry and Forest Products
TitleBuds
Caption
CopyrightJohn Doran/CSIRO Forestry and Forest Products
BudsJohn Doran/CSIRO Forestry and Forest Products
TitleFlowers
Caption
CopyrightJohn Doran/CSIRO Forestry and Forest Products
FlowersJohn Doran/CSIRO Forestry and Forest Products
TitleFruit and seeds
Caption
CopyrightJohn Doran/CSIRO Forestry and Forest Products
Fruit and seedsJohn Doran/CSIRO Forestry and Forest Products

Identity

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Preferred Scientific Name

  • Acacia melanoxylon R. Br.

Preferred Common Name

  • Australian blackwood

International Common Names

  • English: Australian ysterhout; blackwood; blackwood acacia
  • Spanish: Aromo negro
  • French: acacia a bois noir

Local Common Names

  • Australia: swamp blackwood; Tasmanian blackwood
  • Brazil: ébano-da-austrália; madeira-preta; maogani-da-austrália; mogno-da-austrália
  • Germany: Schwarzholz Akazie
  • Italy: acacia nera australiana
  • Netherlands: Australiese Swarthout

EPPO code

  • ACAME (Acacia melanoxylon)

Summary of Invasiveness

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A. melanoxylon is a fast growing nitrogen fixing species, able to grow on a variety of soils, prolifically produces seeds with extreme longevity and high germinability from an early age and is also able to spread from root suckers. Practical difficulties for controlling the species are complicated by conflicts of interest between stakeholders and the species is a particular problem in South Africa. Binggeli (1999) classified A. melanoxylon as highly invasive and it is known to have become invasive in Kenya, South Africa, Tanzania, Argentina and California, USA. In South Africa, the disturbance caused by habitat degradation and fynbos fires promotes A. melanoxylon invasion, and it is classed as a category 2 invader according to the Conservation of Agricultural Resources Act (1983), invading forest margins and clearings, river and stream banks and road edges in both grassland and fynbos habitats.

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Fabales
  •                         Family: Fabaceae
  •                             Subfamily: Mimosoideae
  •                                 Genus: Acacia
  •                                     Species: Acacia melanoxylon

Notes on Taxonomy and Nomenclature

Top of page As currently defined Acacia (family Fabaceae, subfamily Mimosoideae) represents a cosmopolitan genus of 1200-1300 species contained in three subgenera: subgenus Acacia, subgenus Aculeiferum and subgenus Phyllodinae (Maslin, 1995). Acacia melanoxylon is in subgenus Phyllodinae, a group containing in excess of 900 species (Maslin and McDonald, 1996). Within subgenus Phyllodinae the species are grouped into seven sections with A. melanoxylon R. Br. assigned to section Plurinerves (212 species), a group characterized by generally having plurinerved phyllodes and flowers in globular heads.

The name was published in Ait. Hort. Kew. 2nd edn, 5: 462 (1813). The specific name is derived from the Greek melanos - black and xylon - wood, from the wood colour. 'Blackwood' is the common name for the species and is widely used. Acacia frigescens J.H. Willis and A. implexa Benth. are near relatives of A. melanoxylon followed closely by A. oraria F. Muell. and A. cyclops G. Don (B. Maslin pers. comm.). It is also related to the two extra-Australian species A. koa A. Gray (Hawaiian Islands) and A. heterophylla Willd. (Mascarene Islands). Acacia melanoxylon may be confused with A. implexa, but the latter's phyllodes have more open, elongated phyllode reticulum and the colour and arrangement of its funicle/aril differ (Maslin and McDonald, 1996).

Description

Top of page A. melanoxylon is often 10-20 m tall and 0.5 m diameter, but varies from a small shrub to one of the largest acacias in Australia, attaining heights up to 40 m and diameters of 1-1.5 m on lowlands in northwestern Tasmania and in southern Victoria. In open situations, the smaller and medium-sized trees are freely branched from near ground level, but the largest trees have a well-developed trunk which is usually fairly cylindrical, but may be shortly buttressed or flanged at the base. The hard rough bark is brownish-grey to very dark grey and is longitudinally furrowed and scaly, shedding in narrow vertical strips. The relatively wide phyllodes, longitudinal venation, pale flowers and twisted or coiled legumes with red funicles are the key distinguishing features of this species. Botanical descriptions are provided by Pedley (1978), Tame (1992) and Maslin and McDonald (1996). The branchlets are angular with conspicuous ribs; young branchlets are pubescent to hoary, becoming glabrous. The deep or dull-green phyllodes are alternate, simple, narrow-ovate, somewhat falcate or almost straight, 8-13 x 0.7-2 cm and rounded or rarely acute at the tip. There are 3-5 prominent longitudinal veins; pulvinus 2-4 mm long; gland small 1-10 mm above the base; bipinnate foliage often persists to about the 20th node on young plants. The inflorescence consists of 3-5 relatively large globular heads carried on short axillary racemes, 2.5-5 cm long. Each head consists of 30-50 flowers, are whitish to very pale yellow. The legumes are flat, rather thin, 6-10 x 0.4-0.6 cm, mid-brown and when ripe, either irregularly twisted or openly coiled. Seeds are black, oval and flat and 6-10 are carried longitudinally in the pod; funicle is pink or red, half-encircling the seed in a double fold on each side, aril is small.

Plant Type

Top of page Broadleaved
Perennial
Seed propagated
Shrub
Tree
Vegetatively propagated
Woody

Distribution

Top of page A. melanoxylon has a native distribution in Australia through the tablelands and coastal escarpments of southeast Queensland, New South Wales and Victoria to the Mount Lofty Ranges in South Australia and to southern Tasmania. Several disjunctions occur in regions of high elevation (up to about 1000 m) in northern Queensland with the most northerly population being Mt Lewis on the Atherton Tableland (16°S). A description of the natural distribution and ecology of A. melanoxylon is available in Doran and Turnbull (1997).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasivePlantedReferenceNotes

Asia

BhutanPresentIntroducedILDIS, 2002
ChinaPresentIntroducedWang et al., 1994
-GuangdongPresentIntroduced Planted Yang et al., 1994
IndiaPresentIntroducedILDIS, 2002
-KeralaPresentIntroduced Planted
-Tamil NaduPresentIntroduced Planted
JapanPresentIntroduced Planted
PakistanPresentIntroducedILDIS, 2002
Sri LankaPresentIntroduced Planted Midgley and Vivekanandan, 1987
ThailandPresentIntroducedPinyopusarerk and Puriyakorn, 1987

Africa

AlgeriaPresentIntroduced1800sFloc'h E le, 1991
EthiopiaPresentIntroducedKaitho et al., 1996; ILDIS, 2002
KenyaPresentIntroduced Invasive Streets, 1962; ILDIS, 2002; Witt and Luke, 2017
LesothoPresentIntroducedILDIS, 2002
MadagascarPresentIntroduced Planted
MauritiusPresentIntroducedILDIS, 2002
RéunionPresentIntroducedILDIS, 2002
RwandaPresentIntroduced Planted
South AfricaWidespreadIntroduced1848 Invasive Geldenhuys , 1986; Cronk and Fuller , 1995; Henderson , 2001
SwazilandPresentIntroducedILDIS, 2002
TanzaniaPresentIntroduced Invasive Streets, 1962; ILDIS, 2002; Witt and Luke, 2017
ZimbabwePresentIntroduced Invasive Nyoka, 2002; Mitchell and et al. , 1987

North America

USAPresentIntroduced Invasive Cronk and Fuller , 1995; Luken and Thieret , 1997; ILDIS, 2002
-CaliforniaPresentIntroduced Invasive Cronk and Fuller , 1995; Luken and Thieret , 1997; Knapp , 2002
-HawaiiPresentIntroduced Invasive Tunison , 1991; Luken and Thieret , 1997; Weber , 2003

Central America and Caribbean

HaitiPresentIntroduced Planted

South America

ArgentinaPresentIntroduced Invasive Cronk and Fuller , 1995; ILDIS, 2002
BoliviaPresentIntroducedILDIS, 2002
BrazilPresentIntroduced Planted
ChilePresentIntroduced Planted ILDIS, 2002
ColombiaPresentIntroducedILDIS, 2002
PeruPresentIntroduced Planted ILDIS, 2002
UruguayPresentIntroduced Planted ILDIS, 2002
VenezuelaPresentIntroducedILDIS, 2002

Europe

BelgiumPresentIntroducedILDIS, 2002
FrancePresentIntroduced1800sFloc'h E le, 1991; ILDIS, 2002
ItalyPresentIntroducedILDIS, 2002
PortugalPresentIntroduced1800sFloc'h E le, 1991; ILDIS, 2002
-AzoresPresentIntroducedILDIS, 2002; Weber , 2003
SpainPresentIntroduced Invasive Planted ILDIS, 2002
UKPresentIntroducedWeber , 2003

Oceania

AustraliaPresentNativeCronk and Fuller , 1995; ILDIS, 2002; Weber , 2003
-New South WalesPresentNativePlanted, NaturalCronk and Fuller , 1995
-QueenslandPresentNativeRyan and Bell, 1989; Cronk and Fuller , 1995
-South AustraliaPresentNativePlanted, NaturalCronk and Fuller , 1995
-TasmaniaPresentNativeDean and et al. , 1986; Allen, 1992; ILDIS, 2002
-VictoriaPresentNativePlanted, NaturalCronk and Fuller , 1995
-Western AustraliaPresentIntroduced Planted Bell and Bellairs, 1992
New ZealandPresentIntroduced Invasive ILDIS, 2002; Weber , 2003

History of Introduction and Spread

Top of page As an exotic, A. melanoxylon has been most extensively grown in India and South Africa, with plantations in New Zealand and several countries in South America (Gleason, 1986; Nicholas and Gifford, 1995). It is also common in the hill country (1400-2000 m) of Sri Lanka (Midgley and Vivekanandan, 1987) and in the high country (>1200 m) of East Africa (e.g. in Kenya and Tanzania) (Streets, 1962). It is regarded as good or promising in parts of China (Wang et al., 1994), in Guangdong surviving the cold at Hekou although killed by frost at Longdouxie (Yang et al., 1994).

According to information collated by Le Floc'h (1991), A. melanoxylon was introduced to several countries in the western Mediterranean Basin in the 1800s and has subsequently naturalized in Algeria, France and Portugal. It appears listed as dangerous to natural ecosystems on a recently compiled list of plant invaders in Spain (Dana et al., 2004). It was introduced in the Knysna area of Cape Province, South Africa for the suppression of weeds in forest clearings in order to promote native vegetation, thus it is ironic that is has now become a weed in itself (Pryor, 1991). The species is also invasive in neigbouring Zimbabwe (Nyoka, 2002). In the USA, A. melanoxylon has become invasive in California and Hawaii and has naturalized in Hawaii since the 1980s (Luken and Thieret, 1997). Tunison (1991) classed the tree as potentially invasive in Hawaii as it has spread vegetatively in pine plantations in the Waikamoi Preserve, escaping into drainages in some areas. Tunison (1991) predicts that the species appears to rely on vegetative reproduction in Hawaii, but anticipates that if viable seed is produced and stored in the soil, potential large scale invasions are possible in the future. In California it is reported invasive on Catalina island (Knapp, 2002) and is also known to occur in the San Francisco bay area, in central coastal sites and on Santa Cruz island (California Exotic Pest Plant Council, 1999). It is one of a number of species for which California Exotic Pest Plant Council has identified a need for further information. According to Holm et al. (1979), A. melanoxylon is a weed of unspecified importance in New Zealand, a common weed in South Africa and a principal weed in Australia, though no further information regarding its weediness in Australia is forthcoming, but it is known to be beginning to become invasive in New Zealand.

Risk of Introduction

Top of page A. melanoxylon has become naturalized or invasive in a number of continents and is a particular problem in South Africa where it achieves much higher levels of seed production than in its native Australia. As it exhibits many invasiveness traits it is likely to be rejected by risk assessment before further introduction to similar climates, and existing plantations should be monitored for the first signs of invasive behaviour. In Hawaii, USA, the approach of quarantining trees within pine plantations, controlling the escape of suckers and monitoring for signs of viable seed production has been adopted.

Habitat

Top of page A. melanoxylon is predominantly an understorey species in its native Australia. In northern New South Wales and southern Queensland it is often the major early secondary tree species in disturbed temperate (cool and warm) rain forests (Floyd, 1990). The main vegetation types are cool temperate rain forests (nanophyll moss forests) and tall open-forest. Only as a smaller tree is it common in open-forest and, as a small shrub, in mountain heath. It also occurs in teatree (Melaleuca spp.) swamps in Tasmania. A. melanoxylon has a higher tolerance of saturated soil conditions than most eucalypt or rain forest overstorey species and therefore tends to become a more significant component of stands in swampy or seasonally flooded sites. However, the best growth occurs on well-drained soils with A. melanoxylon often occupying mounds and dry banks in swamp conditions. Weber (2003) also lists stream banks among the native habitats.

In its non-native range, A. melanoxylon spreads along forest edges and in forest clearings, in grassland and heathland, scrub and riverine habitats (Weber, 2003). In South Africa it invades fynbos and grassland habitats and in addition to the habitat types listed, is also found along roads (Henderson, 2001), in forest plantations of pine and eucalyptus and on wasteland and agricultural land (Geldenhuys, 1986). Geldenhuys et al. (1986) state that A. melanoxylon is not a successful competitor in closed forest and according to information sources collated by Geldenhuys (1986), the invasive behaviour of this species is limited to humid regions.

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial – ManagedCultivated / agricultural land Present, no further details Harmful (pest or invasive)
Managed forests, plantations and orchards Present, no further details Harmful (pest or invasive)
Disturbed areas Present, no further details Harmful (pest or invasive)
Rail / roadsides Present, no further details Harmful (pest or invasive)
Terrestrial ‑ Natural / Semi-naturalNatural forests Present, no further details Harmful (pest or invasive)
Natural grasslands Present, no further details Harmful (pest or invasive)
Riverbanks Present, no further details Harmful (pest or invasive)

Host Plants and Other Plants Affected

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Plant nameFamilyContext
EucalyptusMyrtaceaeMain
Pinus (pines)PinaceaeMain

Biology and Ecology

Top of page Genetics

As might be expected in a species with such a wide geographic range, there is considerable genetic variation between trees from different localities: in growth traits (Jennings, 1991); in phyllode and fruit shape and size; in the age of change from bipinnate to phyllodineous leaves (Farrell and Ashton, 1978); in frost resistance (Franklin, 1987); and in certain anatomical features of the wood (Wilkins and Papassotiriou, 1989). Isozyme analysis of 27 provenances covering the distribution of A. melanoxylon showed a distinct genetic separation between the northern and southern populations near the Hunter River (ca. 33°S latitude) in New South Wales (Playford et al., 1991, 1993). Populations to the north of the Hunter River were much less heterozygous than the southern populations, although mean heterozygosity levels were high. This separation coincided with a disjunction in the distribution of the species, indicating that the species has evolved separately in the two regions for a considerable time. Southern populations were further divided in northern Victoria. Most of the genetic diversity as assessed by allozyme variation was found within populations, but there was an unusually high level of variation between populations (37.7%). Harris and Young (1988) reported substantial between-tree variation in wood density in a 46-year-old stand of A. melanoxylon in New Zealand, while Nicholas et al. (1994) found significant provenance differences in wood density in 10-year-old trees. A positive association was found between faster-grown trees and darker heartwood, but no association was found between growth rate and density (Harris and Young, 1988).

Physiology and Phenology

A. melanoxylon grows fast and is capable of indefinite production and extension of new shoots from near the crown apex while growing conditions are favourable. It is a long-lived species; in Tasmania some trees have been estimated to be more than 200 years old (Jennings, 1991). Flowering is variable throughout the native range. In the northern part of the range, flowering tends to be in late winter-spring while in the southern part of the range flowering is spring-summer. Ripe seeds are available during summer-autumn with a mid-February peak and little seed is retained on branches beyond April in the southern part of the distribution (Jennings, 1991). The cycle of flower and fruit development in A. melanoxylon is illustrated in Doran (1990).

Reproductive Biology

There is a hermaphrodite breeding system in this species (Cronk and Fuller, 1995). A. melanoxylon may flower from as early as 2 years (Ryan and Bell, 1989) and seeds are generally produced from about the age of five years (Dean et al., 1986). Seeds have a hard seed coat when fully ripened. A large quantity of seeds is produced but remains dormant until a disturbance event (Cronk and Fuller, 1995). There are 64,000 viable seeds/kg with an average germination rate of 75% (Doran and Turnbull, 1997). The rate of germination may be as high as 90-100% (Geldenhuys, 1986). Ground-stored seed from natural seed fall can remain viable for more than 50 years (Searle, 1996). Fire stimulates seedling germination (Cronk and Fuller, 1995; Weber, 2003) as do logging and other soil disturbance events (Geldenhuys et al., 1986). Optimum temperature for germination of A. melanoxylon seed is 25°C but germination occurs throughout the range of 15-35°C (Bell and Bellairs, 1992). Dean et al. (1986) report that the seed crops produced and hence seed density beneath trees may be a thousand times higher in South Africa than in the native Australia range and attributes the invasiveness of this species in part to this factor. Vegetative reproduction from root suckers also takes place and the tree resprouts readily when damaged (Weber, 2003).

Environmental Requirements

The principal occurrence is in the cool and warm humid climatic zones, but it is common in the warm sub-humid zone. The following data pertain to the native range, while Marcar et al. (1995) provide climatic profiles (tabulated) for the species combining information from both natural and planted occurrences. Summers are mild to warm, with mean maximum temperature of the hottest month 23-26°C and mean minimum of the coldest month 1-10°C, with 1-40 heavy frosts a year. Some of the area experiences a few light snowfalls in a year. Mean annual rainfall is 750-1500 mm, with a low to moderate variability; precipitation is mainly on 100-120 days a year, rising to 150-180 where the largest trees grow. Rainfall has a winter maximum in the southern part of the species range, an even distribution in the central part, and a summer maximum in the north. Annual rainfall may reach almost 3000 mm where it has been introduced.

The topography varies from lowland swampy areas and the lower valley slopes of hilly and mountainous areas to higher hill slopes and tablelands and even exposed mountain tops. Best growth is on slightly acidic, forest podzols and alluvia of high nutrient status, but as a smaller tree, A. melanoxylon grows on a wide range of podzols, sandy loams, kraznozems and even the residue from tin sluicing operations.

Associations

Under optimum conditions it is associated with Eucalyptus regnans, E. obliqua, E. delegatensis and E. viminalis; at higher altitudes with Nothofagus cunninghamii and N. moorei, and with one of the larger ferns, Dicksonia antarctica in cool, wet areas. In the drier and warmer areas it is associated with many species of eucalyptus, several other acacias in the understorey and in some places with Xanthorrhoea spp. Associates in the teatree swamps of Tasmania include Melaleuca ericifolia, M. squarrosa, Leptospermum lanigerum and L. scoparium, with N. cunninghamii, Atherosperma moschatum, Eucryphia lucida, Anodopetalum biglandulosum and other rain forest species in the understorey (Allen, 1992). A. melanoxylon is able to fix nitrogen and this provides the opportunity to grow on poor soils (Rutherford et al., 1986). A. nilotica forms associations with rhizobia. Studies in progress in Australia are showing some strains of rhizobia to be much more effective in stimulating growth of A. melanoxylon than others, and seedling development is poor without rhizobia.

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
-16 -43 0 1200

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -7 0
Mean annual temperature (ºC) 9 25
Mean maximum temperature of hottest month (ºC) 19 33
Mean minimum temperature of coldest month (ºC) -3 16

Rainfall

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ParameterLower limitUpper limitDescription
Dry season duration06number of consecutive months with <40 mm rainfall
Mean annual rainfall4802940mm; lower/upper limits

Rainfall Regime

Top of page Bimodal
Summer
Uniform
Winter

Soil Tolerances

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Soil drainage

  • free
  • seasonally waterlogged

Soil reaction

  • acid

Soil texture

  • heavy
  • light
  • medium

Special soil tolerances

  • saline

Notes on Natural Enemies

Top of page Allen (1992) provides a summary of herbivores and pathogens of A. melanoxylon. In natural stands, it is attacked by a wide range of insects but none is of economic consequence (Jennings, 1991). Seedlings may be defoliated by moths or grasshoppers, and larger trees attacked by wood borers, leaf eaters, psyllids and scale insects. Susceptibility to fungal diseases such as Armillaria and Phytophthora appears to be minimal. Significant pests in New Zealand are the ghost moth (Aenetus virescens) and pinhole borers (Platypus spp.) and the impact of a recently reported insect (a chrysomelid) in Auckland is being monitored. Various fungal diseases have been reported on young plants of A. melanoxylon in southern India, including Fusarium semitectum, which causes shoot dieback in two-year-old plants (Mohanan and Sharma, 1988). Whilst relatively free of significant insect attack and pathogens, A. melanoxylon is subject to a substantial number of vertebrate pests in Australia, such as wallabies and rabbits (see Allen, 1992).

Means of Movement and Dispersal

Top of page Seeds may be dispersed by water and by avian vectors (Cronk and Fuller, 1995). The seed possesses large red funicles that are thought to be attractive to birds (Dean et al., 1986). South African birds known to disperse the seeds include Knysna loerie, Tauraco corythaix and the rameron pigeon, Columba arquatrix (Geldenhuys, 1986).

Forestry practice has been to plant the tree in gaps in logged forests, thus enabling it to establish in open forest and forest edges. Most invasive events have been associated with escape from plantations as the tree is well known as a timber species. A. melanoxylon has been widely introduced outside its native Australia and is now grown in Asia, Africa, Europe, and the Americas.

Impact Summary

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CategoryImpact
Animal/plant collections None
Animal/plant products None
Biodiversity (generally) Negative
Crop production None
Environment (generally) Negative
Fisheries / aquaculture None
Forestry production Positive
Human health None
Livestock production None
Native fauna None
Native flora Negative
Rare/protected species Negative
Tourism None
Trade/international relations None
Transport/travel None

Impact

Top of page Geldenhuys (1986) reports economic conflicts of interest in relation to the management of A. melanoxylon in South Africa as its control in areas where it has spread into semi-natural disturbed ecosystems is expensive (negative impact), its value as a timber species reduces exploitation of indigenous species (positive impact), and it performs additional services when it acts as a nurse tree during the restoration of disturbed native forest.

Environmental Impact

Top of page Weber (2003) reports changes in nutrient cycling as the result of deposition of large amounts of litter. This tree uses larger supplies of water than native vegetation so large thickets may change soil moisture conditions (Rutherford et al., 1986). The estimated water use of all the A. melanoxylon in South Africa is estimated to be 21.8 million m3 per year (Anon., 2000). Geldenhuys (1986) cites research that suggests that A. melanoxylon is more prone to windfall than the dominant native forest species in South Africa, Olea capensis subsp. macrocarpa, and that increased disturbance events could promote further invasion by A. melanoxylon.

Impact: Biodiversity

Top of page The dense thickets formed by A. melanoxylon shades out vegetation, which is out competed for supplies of water and light (Weber, 2003).

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Holocarpha macradenia (Santa Cruz tarplant)NatureServe NatureServe; USA ESA listing as threatened species USA ESA listing as threatened speciesCaliforniaCompetition - monopolizing resources; Ecosystem change / habitat alterationUS Fish and Wildlife Service, 2014

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Highly adaptable to different environments
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Highly mobile locally
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Negatively impacts agriculture
  • Reduced native biodiversity
Impact mechanisms
  • Competition - monopolizing resources
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately
  • Difficult/costly to control

Uses

Top of page Open-grown specimens retain their lower branches for many years and form excellent single-row shelterbelts. A. melanoxylon grows well on some exposed sites, without attaining sawlog sizes. It also has a useful role in plantings for shade and beautification in cool to mild climates with adequate rainfall.

A. melanoxylon is recognized as an outstanding cabinet timber in Australia. Formerly exported, supplies have dwindled and the annual production of about 10,000 m³ is now used within Australia. Most timber comes from the natural forests of Tasmania where the resource is actively managed. Supplies from mainland Australia, of which Victoria contributes most (500-1000 m³), are now modest. Blackwood is prized for cabinet work, panelling, inlays, bent work and staves. Availability of large logs is limited and today the timber is mainly used for sliced veneer, especially on particleboard for cabinet work and furniture. The wood has good acoustic qualities and is suitable for violin backs. Small diameter, fast-grown logs do not develop the growth stresses of some eucalypt species and good sawn timber conversion can be expected from trees grown on 40-50-year rotations. Blackwood has good pulpwood potential giving acceptable pulp yields and paper properties favourable for fine papers (Clark et al., 1994). Air dry wood of A. melanoxylon has relatively low density. It ignites easily and burns quickly and quietly with a large flame and little smoke but does not form hot embers (Groves and Chivuya, 1989). The wood is used for fuelwood in India and Sri Lanka, although it is of poor quality for certain cooking requirements and for room heating.

The foliage is harvested for cattle fodder in the Nilgiri Hills region of India, although tests in Australia showed predicted in vivo digestibility at 45%, or below animal maintenance levels (Vercoe, 1987). It was classed as highly palatable in sheep grazing trials in Ethiopia (Kaitho et al., 1996).

Uses List

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Animal feed, fodder, forage

  • Fodder/animal feed

Environmental

  • Agroforestry
  • Revegetation
  • Shade and shelter

Fuels

  • Fuelwood

General

  • Ornamental

Materials

  • Carved material
  • Miscellaneous materials
  • Wood/timber

Wood Products

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Furniture

Veneers

Woodware

  • Turnery
  • Wood carvings

Similarities to Other Species/Conditions

Top of page A. melanoxylon may be confused with A. implexa, but the latter's phyllodes have more open, elongated phyllode reticulum and the colour and arrangement of its funicle/aril differ (Maslin and McDonald, 1996).

Prevention and Control

Top of page On Hawaii, A. melanoxylon is quarantined inside pine plantations (with control of escaping root suckers) until the extent of potential reproduction and recruitment is more fully understood (Tunison, 1991). If attempting mechanical control, due to the ability of A. melanoxylon to reproduce vegetatively from root suckers it is important to remove the roots completely (Weber, 2003). Mature specimens may be felled in combination with the application of a herbicide to the stump to restrict resprouting (Weber, 2003). Large trees may also be killed by ring barking (Geldenhuys, 1986). On Hawaii the control of root sprouts has been prioritised (Tunison, 1991). In Waikamoi Preserve in Hawaii, garlon has been used experimentally on cut stumps (Tunison, 1991).

A seed predating weevil Melanterius acaciae was tested for specificity for potential release in South Africa (Neser and Kluge, 1986) and was first released in 1985, and the Plant Protection Research Institute now releases this species for control where required (ARC, 2000), reporting that the weevils achieve more than 90% seed predation thus reducing the number of seeds that accumulate in the soil. Tunison (1991) comments that biological control is not yet required and would not be a viable control approach on Hawaii, USA.

References

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Links to Websites

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WebsiteURLComment
GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gatewayhttps://doi.org/10.5061/dryad.m93f6Data source for updated system data added to species habitat list.
Global register of Introduced and Invasive species (GRIIS)http://griis.org/Data source for updated system data added to species habitat list.

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