Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Acacia saligna
(Port Jackson wattle)

Toolbox

Datasheet

Acacia saligna (Port Jackson wattle)

Summary

  • Last modified
  • 23 October 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Acacia saligna
  • Preferred Common Name
  • Port Jackson wattle
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • A. saligna, a fast-growing, drought-tolerant nitrogen-fixing tree from southwestern Western Australia has been widely planted through the world’s drylands, especially around the Mediterranean basin, for fodder,...

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report

Pictures

Top of page
PictureTitleCaptionCopyright
Tree of Acacia saligna showing shrubby habit.  Mt. Ragged, Western Australia.
TitleTree
CaptionTree of Acacia saligna showing shrubby habit. Mt. Ragged, Western Australia.
CopyrightM.W. McDonald/CSIRO FFP
Tree of Acacia saligna showing shrubby habit.  Mt. Ragged, Western Australia.
TreeTree of Acacia saligna showing shrubby habit. Mt. Ragged, Western Australia.M.W. McDonald/CSIRO FFP
Flowering branch of Acacia saligna showing shrubby habit.  Cape Riche, Western  Australia.
TitleFlower
CaptionFlowering branch of Acacia saligna showing shrubby habit. Cape Riche, Western Australia.
CopyrightM.W. McDonald/CSIRO FFP
Flowering branch of Acacia saligna showing shrubby habit.  Cape Riche, Western  Australia.
FlowerFlowering branch of Acacia saligna showing shrubby habit. Cape Riche, Western Australia.M.W. McDonald/CSIRO FFP
Seed pods of Acacia saligna showing shrubby habit.  Killcare, NSW,  Australia.
TitleSeed pods
CaptionSeed pods of Acacia saligna showing shrubby habit. Killcare, NSW, Australia.
CopyrightM.W. McDonald/CSIRO FFP
Seed pods of Acacia saligna showing shrubby habit.  Killcare, NSW,  Australia.
Seed podsSeed pods of Acacia saligna showing shrubby habit. Killcare, NSW, Australia.M.W. McDonald/CSIRO FFP

Identity

Top of page

Preferred Scientific Name

  • Acacia saligna (Labill.) H. L. Wendl.

Preferred Common Name

  • Port Jackson wattle

Other Scientific Names

  • Acacia bracteata Maiden & Blakeley
  • Acacia cyanophylla Lindl.
  • Acacia lindleyi Meissner
  • Mimosa saligna Labill.
  • Racosperma salignum (Labill.) Pedley

International Common Names

  • French: acacia blue; mimosa bleuté

Local Common Names

  • Australia: blue-leafed wattle; coojong; golden-wreath wattle; orange wattle; Port Jackson willow; weeping wattle; Western Australian golden wattle
  • Germany: Akazie, Blaublättrige; Akazie, Weiden-
  • Italy: mimosa a foglie blu

EPPO code

  • ACACY (Acacia cyanophylla)
  • ACASA (Acacia saligna)

Summary of Invasiveness

Top of page

A. saligna, a fast-growing, drought-tolerant nitrogen-fixing tree from southwestern Western Australia has been widely planted through the world’s drylands, especially around the Mediterranean basin, for fodder, fuelwood, sand stabilization, as a windbreak and as an ornamental garden or street tree. Referring to invasion of threatened Cape Floristic vegetation in South Africa, it was called “one of the worst woody invaders, a plant that has run amuck in a threatened biome, rich in endemic plant species” (Cronk and Fuller, 1995), however, a successful biocontrol programme has since largely contained the problem there. It has more recently escaped and spread invasively in parts of Cyprus, Portugal and Spain, and has naturalised and spread in southern and eastern Australia and elsewhere where introduced. It continues to be planted, especially in North Africa and West Asia, but caution is now advised as prolific seed production, ready coppicing and suckering ability, and rapid growth on even the poorest of sites make it a high risk species.

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 saligna

Notes on Taxonomy and Nomenclature

Top of page

A. saligna is a phyllodinous Australian acacia belonging to the subgenus Racosperma, commonly known as ‘wattles’ or wattle trees. Pedley (1986) proposed to raise Racosperma to genus level, a move opposed by many taxonomists, as summarised by Orchard and Maslin (2003). It is important to note that one of the old synonyms, Acacia cyanophylla is still widely but incorrectly used in parts of the introduced range to this day, although Le Houérou (2002) defends his use of the older name “known for decades” only “for reasons of convenience”.

Description

Top of page

The following description is adapted from Vercoe and McDonald (1987), Whibley and Symon (1992), Crompton (1992), Cronk and Fuller (1995) and Fox (1995). A. saligna is a dense and multi-stemmed, thornless, spreading shrub or single stemmed small tree 2-6 m tall, but up to 9 m in height where introduced. Where it has become naturalised however, it is commonly a dense bush which may be wider than the plant is high. The bark is smooth and grey to red-brown on branchlets, becoming dark grey and fissured with age. Leaves are phyllodes, dark green to blue-green with conspicuous midribs, long and narrow to lanceolate and 8-25 cm long, straight or sickle-shaped and sometimes pendulous. Phyllodes may also be prominently broader at the base. There is a solitary gland on the upper margin of the phyllode, circular or oblong, 1-2 mm in diameter. Inflorescence racemose, flower heads globular, 5-10 mm in diameter, containing 25-55 (up to 78) bright yellow, five-parted flowers. The pods are narrow, 4-6 mm wide and usually 8-12 cm long, usually contracted between the seeds and with an undulate surface. The seed is 5-6 mm long x 3-3.5 mm wide, dark brown to black and shiny, with 14,000-25,000 seeds per kg.

Plant Type

Top of page Broadleaved
Perennial
Seed propagated
Shrub
Tree
Woody

Distribution

Top of page

A. saligna is native to southwestern Western Australia, where it is very common on the poor sandy soils of the Swan Coastal Plain from Gingin southwards to Busselton and the coast (35°S), and on heavier clay soils as far north as the Murchison River (27°S). It is found from the coast (115°E) inland to about 200 km east of Esperance (122°E).

Distribution Table

Top of page

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

IndiaPresentIntroducedILDIS, 2007
-GujaratPresent Planted CABI, 2005
-HaryanaPresent Planted CABI, 2005
-Indian PunjabPresent Planted CABI, 2005
-KarnatakaPresent Planted CABI, 2005
-MaharashtraPresent Planted CABI, 2005
-RajasthanPresent Planted CABI, 2005
-Tamil NaduPresent Planted CABI, 2005
-Uttar PradeshPresent Planted CABI, 2005
IranPresentIntroduced Planted Dommergues et al., 1999
IraqPresentIntroducedILDIS, 2007
IsraelPresentIntroduced Planted ILDIS, 2007
JordanPresentIntroduced Planted ILDIS, 2007
KuwaitPresentIntroduced Planted CABI, 2005
PakistanPresentIntroduced Planted ILDIS, 2007
Saudi ArabiaPresentIntroduced Planted ILDIS, 2007
SyriaPresentIntroduced Planted Dommergues et al., 1999
TurkeyPresentIntroducedKaraca et al., 1999
YemenPresentIntroducedILDIS, 2007

Africa

AlgeriaPresentIntroduced Not invasive Planted El-Lakany, 1988
BotswanaPresentIntroduced Planted CABI, 2005
BurundiPresentIntroduced Planted CABI, 2005
ChadPresentIntroduced Planted CABI, 2005
EgyptPresentIntroduced Not invasive Planted El-Lakany, 1988
EthiopiaPresentIntroduced Invasive ILDIS, 2007; Witt and Luke, 2017
GambiaPresentIntroduced Planted CABI, 2005
KenyaPresentIntroduced Planted ILDIS, 2007
LibyaPresentIntroduced Not invasive Planted ILDIS, 2007
MauritiusPresentIntroducedILDIS, 2007
MoroccoPresentIntroduced Not invasive Planted El-Lakany, 1988
MozambiquePresentIntroducedILDIS, 2007
NamibiaPresentIntroducedILDIS, 2007
NigerPresentIntroduced Planted CABI, 2005
SenegalPresentIntroduced Planted CABI, 2005
SomaliaPresentIntroduced Planted CABI, 2005
South AfricaPresentIntroduced1833 Invasive Cronk and Fuller, 1995; ILDIS, 2007
Spain
-Canary IslandsPresentIntroducedLe Houérou, 2002
SudanPresentIntroduced Planted CABI, 2005
TanzaniaPresentIntroduced Planted ILDIS, 2007
TunisiaPresentIntroduced Not invasive Planted El-Lakany, 1988
UgandaPresentIntroducedILDIS, 2007
ZambiaPresentIntroducedILDIS, 2007

North America

MexicoPresentIntroduced Planted Dommergues et al., 1999
USALocalisedIntroducedILDIS, 2007
-CaliforniaPresentIntroducedILDIS, 2007; USDA-NRCS, 2007

South America

ArgentinaPresentIntroduced Planted ILDIS, 2007
BoliviaPresentIntroducedILDIS, 2007
ChilePresentIntroduced Invasive Planted ILDIS, 2007
PeruPresentIntroduced Planted Coates, 2005
UruguayPresentIntroduced Planted Dommergues et al., 1999

Europe

CyprusPresentIntroduced Invasive Hadjikyriakou and Hadjisterkotis, 2005; ILDIS, 2007
FrancePresentIntroducedILDIS, 2007
GreecePresentIntroducedILDIS, 2007
ItalyPresentIntroducedILDIS, 2007
PortugalPresentIntroduced Invasive Marchante and Marchante, 2005; ILDIS, 2007
SpainPresentIntroduced Invasive Sanz-Elorza et al., 2001; ILDIS, 2007

Oceania

AustraliaPresentPresent based on regional distribution.
-New South WalesPresentIntroduced Invasive Planted ILDIS, 2007
-QueenslandPresentIntroduced Invasive Planted ILDIS, 2007
-South AustraliaPresentIntroduced Planted ILDIS, 2007
-TasmaniaPresentIntroducedILDIS, 2007
-VictoriaPresentIntroduced Planted ILDIS, 2007
-Western AustraliaPresentNative Not invasive Natural ILDIS, 2007
New ZealandPresentIntroducedILDIS, 2007North Island

History of Introduction and Spread

Top of page
A. saligna has been introduced to southern and eastern Australia, and is now naturalized from South Australia and Victoria to southeast Queensland from escapes from plantings for sand mine reclamation work in northern New South Wales (Stanley and Ross, 1983). It has been widely introduced to arid and semi-arid sites with tropical, sub-tropical or Mediterranean climates throughout the world for soil conservation, for fuelwood and fodder, for tannins and gums, and as an ornamental. It is likely that there are exact records for dates of introduction, beginning with its introduction to South Africa in about 1833 (Cronk and Fuller, 1995), and ending with reforestation species trials in the 1980s and 1990s. It has naturalised in many of these countries, notably in Mediterranean basin, in South Africa and California, USA, but it is considered to be an invasive weed only in South Africa, more recently in the Mediterranean, and it is noted to be spreading rapidly in South Australia. It is one of the most invasive woody weeds in Spain (Sanz-Elorza et al., 2001). In Portugal, it invades sand dunes and is a risk in southern and central coastal regions (Marchante and Marchante, 2005). In Cyprus, it has naturalised and “is the most serious invasive species on Cyprus, threatening many natural habitats, invading forests, maquis, gangue, phrygana, marshy areas and agricultural land, becoming a serious weed” (Hadjikyriakou and Hadjisterkotis, 2005). However, in Israel, since introduction to coastal sand dunes in Israel, A. saligna recorded a mean annual increase in area of only 3% after 34 years, with a 20 year ‘arrival stage’ and 8 years of ‘establishment stage’ (Bar et al., 2004). There are also unconfirmed reports of it being an invasive species in Chile.

A. saligna is not recorded on islands in the Caribbean (Kairo et al., 2003) or Pacific (PIER, 2007), where it could clearly become invasive.

Risk of Introduction

Top of page

Being a valuable and hardy species with ornamental value, it is likely that further intentional introduction may occur. Areas particularly at risk are those where it as yet does not occur, notably potentially sensitive areas such as Caribbean, Pacific and Indian Ocean islands. It is a Declared Invader (category 2) species in South Africa (Henderson, 2001), and a weed risk assessment for South Australia produced a high risk score for A. saligna (Melland and Virtue, 2002), and thus it may be assumed that this species may also be high risk for other similar areas. Steps should then be taken to highlight the risks posed by invasion of A. saligna, also using its old but still commonly used synonym, A. cyanophylla.

Habitat

Top of page

In it native Western Australia, it grows best on deep sands and loams associated with watercourses, and in coastal dunes, more commonly in the hollows between dunes (Cronk and Fuller, 1995). It is also found on disturbed roadsides, and further inland in the wheatbelt, populations occur at the base of many of the large, granitic rock outcrops. It has spread on a variety of habitat types in South Africa including the fynbos, forest, karro and grassveld, where it has also spread to waterways and irrigation channels Africa. Its hardiness and ability to coppice rapidly after fires or from trunks has also led to widespread establishment (Stirton, 1980).

Habitat List

Top of page
CategoryHabitatPresenceStatus
Littoral
Coastal areas Present, no further details Harmful (pest or invasive)
Coastal areas Present, no further details Natural
Coastal dunes Present, no further details Harmful (pest or invasive)
Coastal dunes Present, no further details Natural
Coastal dunes Present, no further details Productive/non-natural
Terrestrial-managed
Cultivated / agricultural land Present, no further details Harmful (pest or invasive)
Cultivated / agricultural land Present, no further details Productive/non-natural
Disturbed areas Present, no further details Harmful (pest or invasive)
Disturbed areas Present, no further details Natural
Managed forests, plantations and orchards Present, no further details Harmful (pest or invasive)
Managed forests, plantations and orchards Present, no further details Productive/non-natural
Rail / roadsides Present, no further details Natural
Urban / peri-urban areas Present, no further details Productive/non-natural
Terrestrial-natural/semi-natural
Arid regions Present, no further details Harmful (pest or invasive)
Arid regions Present, no further details Natural
Arid regions Present, no further details Productive/non-natural
Deserts Present, no further details Harmful (pest or invasive)
Deserts Present, no further details Natural
Deserts Present, no further details Productive/non-natural
Natural 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)
Riverbanks Present, no further details Natural
Scrub / shrublands Present, no further details Harmful (pest or invasive)
Scrub / shrublands Present, no further details Natural
Scrub / shrublands Present, no further details Productive/non-natural
Wetlands Present, no further details Harmful (pest or invasive)

Biology and Ecology

Top of page
Genetics
 
A. saligna has a chromosome number of 2n=26 (Crompton, 1992), and is a relatively variable species in terms of habit. El-Lakany (1987; 1988) noted wide variability between trees and suggested that useful gains might be obtained through breeding. Le Houérou (2002) identified two distinct types, ‘A’ with an intricate bushy habit, long narrow phyllodes and a high leaf:stem ratio thus more suitable for forage production, whereas type ‘B’ has a more erect habit, broad phyllodes and low leaf:stem ration, suitable for firewood production.
 
Reproductive Biology
 
A. saligna reproduced almost entirely by seed and is an outcrossing species, however, it is known to produce root suckers also and a single tree may form a clump or small colony (Whibley and Symon, 1992). It produces seed in large numbers and builds up a significant seed bank, which can germinate rapidly after fire or sufficient rain. Like most legume seed, they can remain dormant in the soil for considerable periods of time. It is relatively precocious, producing seeds often in the first year or two after germination, depending on site.
 
Physiology and Phenology
 
A. saligna is relatively short-lived in cultivation (10-20 years). It grows quickly in favourable conditions, often reaching 8 m tall with a spread as great as its height in 4-5 years. It coppices well, and annual wood yields vary from 1.5-10 cubic metres/ha (National Academy of Sciences USA, 1980). In the arid zone of Tunisia and Libya, A. saligna produces fuelwood at an annual rate of up to 3500 kg dry-wood/ha on deep sandy loam alluvia receiving an average of 150 mm annual precipitation and some runoff (El-Lakany, 1987). Annual harvesting for biomass production in Egypt was found to be optimal in drip-irrigated trials where production of foliage was 12-13 t/ha in the first year and increased with age (El-Lakany, 1988). In trials in a sub-tropical area in southeast Queensland, A. saligna attained an average height of 6.2 m after only 41 months but slowed down substantially in the following year to average 6.7 m at 4.5 years (Ryan and Bell, 1989; 1991).
 
Associations
 
The tree nodulates with certain strains of Rhizobium (Roughley, 1987), and in common with many other acacias, it forms associations with VA mycorrhizal fungi (Reddell and Warren, 1987). It is efficient in fixing atmospheric nitrogen (El-Lakany, 1987), though the ability of A. saligna to fix nitrogen is greatly reduced by drought, waterlogging, shading or defoliation (Nakos, 1977).
 
Observations of A. saligna in Western Australia support the hypothesis that the extrafloral nectaries at the base of the phyllodes provide nutrients or water to ants, which in turn protect against herbivory. Most insects collected were herbivores, along with. The spatial and temporal patterns of nectary secretion (very active on new leaves and in the spring and autumn) were consistent with maximizing the protective function of ants (Majer, 1979), with 19 species of aggressive ants collected from A. saligna in the native range
 
Environmental Requirements
 
In Australia, A. saligna has its main occurrence in the warm, sub-humid and humid climatic zones, but it extends into the higher rainfall parts of the semi-arid zone. The mean maximum temperatures of the hottest month show a considerable range from about 23°C on parts of the south coast to nearly 30°C at Perth, to 32-36°C for northern and inland locations. The mean minimum of the coolest month shows a smaller range, being mainly within the limits of 4.5-9°C. Most situations on the coast are frost-free, especially from Perth northwards, but inland there is an average of 1-6 frosts per year. Where introduced, A. saligna exhibits frost sensitivity, and damage is likely to be severe if the temperature falls below –4oC. A. saligna generally grows poorly in tropical areas as compared to other acacia species, except at high altitudes.

The mean annual rainfall for the native range humid zone is 750-1000 mm, with an abrupt drop for the sub-humid zone to 450-500 mm, and as low as 280 mm in the semi-arid zone (Doran et al., 1997), but where it normally receives additional run-on water (Crompton, 1992). A. saligna occurs on many soil types, especially poor and calcareous sands, but also moderately heavy clays and on a range of podzolics. Trees are common on alkaline, infertile sandy soils (Simmons, 1981). It mainly grows on gentle undulating topography and coastal sand plains, but extends to a wide variety of situations from swampy sites and river banks to small, rocky hills (often granitic) and the slopes of the coastal ranges (Doran et al., 1997). It can tolerate waterlogging and salt winds, and altitudes from sea level to about 325 m elevation in its native range, but much higher where introduced.

Climate

Top of page
ClimateStatusDescriptionRemark
As - Tropical savanna climate with dry summer Tolerated < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Tolerated < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
B - Dry (arid and semi-arid) Preferred < 860mm precipitation annually
BS - Steppe climate Preferred > 430mm and < 860mm annual precipitation
BW - Desert climate Preferred < 430mm annual precipitation
Cf - Warm temperate climate, wet all year Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers

Latitude/Altitude Ranges

Top of page
Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
40 40

Air Temperature

Top of page
Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -4 -1
Mean annual temperature (ºC) 13 21
Mean maximum temperature of hottest month (ºC) 26 36
Mean minimum temperature of coldest month (ºC) 4 9

Rainfall

Top of page
ParameterLower limitUpper limitDescription
Dry season duration010number of consecutive months with <40 mm rainfall
Mean annual rainfall2801000mm; lower/upper limits

Rainfall Regime

Top of page Bimodal
Uniform
Winter

Soil Tolerances

Top of page

Soil drainage

  • free
  • impeded
  • seasonally waterlogged

Soil reaction

  • acid
  • alkaline
  • neutral

Soil texture

  • heavy
  • light
  • medium

Special soil tolerances

  • infertile
  • saline
  • shallow
  • sodic

Notes on Natural Enemies

Top of page
Early interest in the protection of A. saligna as a valuable dryland plantation species for fuel or fodder is now replaced by the assessment of species-specific pests and pathogens for use in controlling A. saligna as an invasive weed. For example, it was noticed that older plants are susceptible to the gall rust Uromycladium tepperianum and various gall-exploiting insects. More than 90% of A. saligna trees bear conspicuous woody galls in parts of the native range in Western Australia (van den Berg, 1978). U. tepperianum has been used successfully as a biological control agent for A. saligna in South Africa (de Selincourt, 1992) and Morris (1999) recorded a reduction in populations to 5-10% of original tree densities at eight sites after 7-8 years.

Arthropod natural enemies of A. saligna in Western Australia have been studied by van den Berg (1980a, 1980b, 1980c), and the larvae of 36 species of moths and butterflies were found, with those damaging the phyllodes being the most common. The adults or larvae of 55 species of beetles and weevils and the adults and/or nymphs of 40 species of cicadas, plant hoppers, plant lice, scale insects and bugs were also recorded, with those feeding on sap and twigs most abundant.

Other pests noted as attacking A. saligna elsewhere in the world are Scirothrips dorsalis producing 'bunchy-top' symptoms in a glasshouse in Queensland, Australia (Ashwath and Houston, 1990), Odontothrips confusus in Israel (Strassen and Halperin, 1990), the oleander scale, Aspidiotus nerii, and its predators in Turkey (Karaca et al., 1999), Lindingaspis rossi and a parasite (Habrolepis sp.) in Egypt (Swailem et al., 1980) and Icerya purchasi in Ethiopia (Getu, 1996). Termites may also cause serious problems in tropical countries (Michaelides, 1979) and rodents sometimes gnaw and damage the roots.

Means of Movement and Dispersal

Top of page
Natural Dispersal (Non-Biotic)
 
The seed is spread along rivers and watercourses (Cronk and Fuller, 1995).
 
Vector Transmission (Biotic)
 
Seeds can be spread by birds, such as doves and starlings in South Africa (Cronk and Fuller, 1995)
 
Accidental Introduction
 
It is reported that seed can be spread in sand transported for road and dam construction (Cronk and Fuller, 1995).
 
Intentional Introduction 

All long-distant movement of A. saligna has been intentional, introduced for over 150 years for protection (soil conservation, dune stabilization, erosion control), production (fuelwood, fodder, tannins) and aesthetics (as an ornamental garden and street tree).

Pathway Vectors

Top of page
VectorNotesLong DistanceLocalReferences
Soil, sand and gravelWith sand for construction Yes Cronk and Fuller, 1995
WaterAlong watercourses Yes Cronk and Fuller, 1995

Impact Summary

Top of page
CategoryImpact
Environment (generally) Positive and negative

Impact

Top of page
Economic Impact
 
A. saligna continues to be promoted as a multipurpose tree species, mostly as a source of firewood and fodder even during droughts, and, for soil conservation. By 1987, over 200,000 ha of A. saligna plantations had been planted in North Africa, and a few thousand in southeastern Spain and West Asia (Le Houérou, 2002), based on the observed positive economic impacts for resource production.
 
Social Impact
 
Valued as street and garden tree, especially in the Middle East and North Africa, A. saligna has a positive impact.
 
Environmental Impact

Impact on habitats
 
It is a major environmental weed in South Africa (ILDIS, 2007). The phyllodes have a greater nitrogen content that many native species in South Africa, thus leading to increasing nitrogen levels in the soil in invaded areas (Cronk and Fuller, 1995), and the observed increase in total soil nitrogen and soil organic matter under A. saligna and after clearance was explained by the slow decomposition of the litter (Yelenik et al., 2007). The alteration of nitrogen availability by acacias was shown to increase growth rates of the weedy grass Ehrharta calycina, suggesting that secondary invasions by nitrophilous weedy species may occur after clearing nitrogen-fixing alien species in the fynbos (Yelenik et al., 2004). The foliage has also been found to have allelopathic qualities when tested on maize and rice germination (El Baha, 2003). Tilstone et al. (1998) observed significant differences in the growth of A. saligna in different native vegetation communities in Spain, but also that there were environmental benefits from introducing fast-growing exotic trees to control the rampant soil erosion that continues in the region.
 
Impact on biodiversity

A. saligna was noted as the most troublesome invasive weed in the Cape Floritic region in South Africa (Wood and Morris, 2007), and was recorded as threatening several IUCN listed threatened species in South Africa: Chondropetalum acockii, Gladiolus aureus, Leucadendron verticillatum, Restio acockii, Serruria ciliata (Cronk and Fuller, 1995), though it may be expected that this threat has reduced since the successful biological control programme.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Fast growing
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
  • Reproduces asexually
  • Has high genetic variability
Impact outcomes
  • Ecosystem change/ habitat alteration
  • Modification of fire regime
  • Modification of hydrology
  • Modification of nutrient regime
  • Modification of successional patterns
  • Monoculture formation
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Allelopathic
  • Competition - monopolizing resources
  • Competition - shading
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately

Uses

Top of page
In southwest Western Australia, native A. saligna is a successful farm tree for reduction of water tables and mitigation of salinity, provision of shade and shelter, and reduction in farm nutrient run-off. It is well-suited to heavy saline and waterlogged clay soils where it gives fast growth, excellent survival and large crown growth (Bennett and George, 1993). A. saligna has been successfully established in Western Australia by direct sowing in regions with annual rainfall as low as 350-500 mm (Scheltema, 1992). It is also used elsewhere in Australia for rehabilitation of areas mined for coal and mineral sands (Langkamp, 1987).
 
A. saligna is a versatile hardy plant widely cultivated in North Africa, the Middle East and South America for agroforestry, wasteland utilization and soil conservation purposes (Crompton, 1992). Over 200,000 ha have been planted in North Africa as a fodder source for sheep and goats. In highland Tanzania it is grown for windbreaks, fencing and fuelwood (Kessy, 1987), and in agroforestry systems in Kenya (Droppelmann and Berliner, 2003). Studies in Western Australia have suggested that A. saligna alleys are of use in agroforestry as they encourage beneficial arthropods in cropping systems (Lyons and Majer, 1999).

The wood is used as fuel and charcoal, and A. saligna was among a group of acacias assessed as being reasonably satisfactory for this purpose by Hall (1939). The group gave a charcoal yield of 24% and had medium specific gravity and low tar yield (13.5-17%). The wood has an air dry density of about 600 kg/cubic metre (Marcar et al., 1995). A. saligna wood has been successfully processed into particleboard in Tunisia (El-Lakany, 1987), and elsewhere in the Mediterranean region it is used for vine stakes and small agricultural implements (Michaelides, 1979).
 
A. saligna phyllodes, young shoots, pods and seeds, whether fresh or dry, are protein-rich, non-toxic and palatable to both sheep and goats (Anon, 1955; Michaelides, 1979). However, the phyllodes should not be used as a sole diet for small ruminants (sheep and goats) because of low intake and negative nitrogen balance, caused mainly by high tannin content (Woodward and Reed, 1989; Degen et al., 1995), but it has potential as a supplementary fodder due to its high crude protein content. The fodder value of A. saligna for Barki sheep was evaluated and compared to alfalfa in Egypt (El-Lakany, 1988), and replacing 50% of daily dry matter intake of alfalfa by acacia foliage increased the total digestible nutrients and decreased digestible protein of feed intake, whereas feeding alfalfa alone constitutes a waste of protein, and mixing it improves feeding efficiency. It is especially valuable during the dry season when other forage is scarce, and regrowth on established bushes of A. saligna can be completely grazed-off in autumn without harming the plants. The chemical composition is: dry matter (50-55%), crude protein (12-16%), crude fibre (20-24%), crude fat (6-9%), and ash (10-12%) (El-Lakany, 1987). Analysis of phyllodes from trial plantings in southeast Queensland indicate a moderately low digestibility (36.5% predicted in vivo) but high levels of crude protein (18.3%) (Vercoe, 1989). The low Ca:P ratio of 4:1 should enable efficient use of phosphorus supplements.

Trees were planted in the past for tannin production from the bark, which contains 30% tannin (Hall and Turnbull, 1976). Damaged bark exudes copious amounts of very acidic gum, and such acid-stable gum has promise for use for pickles and other acidic foodstuffs (Michaelides, 1979). The leaves of A. saligna can be used to dye wool a lemon-yellow colour using an alum mordant (Martin, 1974). Seed has also been fed to chicks in Cyprus (Ramadan, 1957), and has been considered as a potential source of human food in Australia (McDonald et al., 2002).

A. saligna is also well known for its protective functions, being widely planted for soil conservation purposes, as a windbreak, to stabilise shifting sand dunes, and in erosion control on slopes and wind-prone areas. It has been used to reclaim old mine spoils, landfill sites and other polluted areas (e.g. Coates, 2005). It is also an attractive ornamental species, and is commonly found in gardens and as a street tree, especially in the Mediterranean basin and the Middle East.

Uses List

Top of page

Animal feed, fodder, forage

  • Fodder/animal feed
  • Forage

Environmental

  • Agroforestry
  • Amenity
  • Boundary, barrier or support
  • Erosion control or dune stabilization
  • Land reclamation
  • Ornamental
  • Revegetation
  • Shade and shelter
  • Soil conservation
  • Soil improvement
  • Windbreak

Fuels

  • Charcoal
  • Fuelwood

General

  • Ornamental

Human food and beverage

  • Emergency (famine) food

Materials

  • Dye/tanning
  • Gum/resin
  • Wood/timber

Wood Products

Top of page

Charcoal

Roundwood

  • Stakes

Wood-based materials

  • Particleboard

Similarities to Other Species/Conditions

Top of page

A. saligna is sometimes confused with A. pycnantha, but it can be generally and easily distinguished from all other commonly introduced Australian acacias from the size, shape and colour of the phyllodes, and any confusion can be resolved with the use of a simple field guide.

Gaps in Knowledge/Research Needs

Top of page

Further research may be illuminating, in understanding why A. saligna has become an invasive species in the European Mediterranean (Cyprus, Portugal and Spain) but not in North Africa or the Middle East.

References

Top of page

Anon, 1955. Acacia cyanophylla as a forage species. Rep. For. Dep. Cyprus 1954 (66)

Ashwath N, Houston K, 1990. Thrips cause bunchy top in Acacia auriculiformis. Nitrogen Fixing Tree Research Reports, 8:95-97

Bar P, Cohen O, Shoshany M, 2004. Invasion rate of the alien species Acacia saligna within coastal sand dune habitats in Israel. Israel Journal of Plant Sciences, 52(2):115-124

Bennett D, George R, 1993. Performance of tree species on the coastal plain. Department of Agriculture, unpublished report, Bunbury, Western Australia

Berg MA van den, 1978. Natural enemies of certain acacias in Australia. Proc. 2nd Nat. Weeds Conf. S. Afr., 75-82

Berg MAvan den, 1980. Natural enemies of Acacia cyclops A. Cunn. ex G. Don and Acacia saligna (Labill.) Wendl. in Western Australia. I. Lepidoptera. Phytophylactica, 12(3):165-167

Berg MAvan den, 1980. Natural enemies of Acacia cyclops A. Cunn. ex G. Don and Acacia saligna (Labill.) Wendl. in Western Australia. II. Coleoptera. Phytophylactica, 12(3):169-171

Berg MAVan Den, 1980. Natural enemies of Acacia cyclops A. Cunn. ex G. Don and Acacia saligna (Labill.) Wendl. in Western Australia. III. Hemiptera. Phytophylactica, 12(4):223-226

CABI, 2005. Forestry Compendium. Wallingford, UK: CABI

Coates W, 2005. Tree species selection for a mine tailings bioremediation project in Peru. Biomass and Bioenergy, 28(4):418-423. http://www.sciencedirect.com/science/journal/09619534

Crompton H, 1992. Acacia saligna - for dryland fodder and soil stabilization. NFT Highlights, No. 92-03:2 pp.; 10 ref

Cronk QCB, Fuller JL, 1995. Plant invaders: the threat to natural ecosystems. London, UK; Chapman & Hall Ltd, xiv + 241 pp

Degen AA, Becker K, Makkar HPS, Borowy N, 1995. Acacia saligna as a fodder tree for desert livestock and the interaction of its tannins with fibre fractions. Journal of the Science of Food and Agriculture, 68(1):65-71; 32 ref

Dommergues Y, Duhoux E, Diem HG, 1999. Les Arbres Fixateurs d'Azote: Caractéristiques Fondamentales et Ro^circumflex~le dans L'aménagement des Écosystèmes Méditerranéens et Tropicaux. Montpellier, France: CIRAD

Droppelmann K, Berliner P, 2003. Runoff agroforestry - a technique to secure the livelihood of pastoralists in the Middle East. Journal of Arid Environments, 54(3):571-577

El-Baha AM, 2003. Allelopathic effects of some multipurpose tree species on germination and growth of same tree seeds and some field crops. Alexandria Journal of Agricultural Research, 48(3):227-237

El-Lakany MH, 1987. Use of Australian acacias in north Africa. ACIAR Proceedings, Australian Centre for International Agricultural Research, No. 16, 116-117; In: Turnbull JW, ed. Australian acacias in developing countries. Proceedings of an international workshop, Gympie, Qld., Australia, 4-7 August 1986

El-Lakany MH, 1988. Experience with some Australian species as multipurpose trees in Egypt and North African countries. The international forestry conference for the Australian Bicentenary 1988. Proceedings of papers contributed and-or presented and histories of Australian forestry and forest products institutions and associations. Friday 29th April. Volume V of V. Albury-Wodonga 25th April-1st May 1988, 6 pp.; 9 ref

Fox JED, 1995. A review of the ecological characteristics of Acacia saligna (Labill) H Wendl. Mulga Research Centre Journal, 12:39-56; 5 pp. of ref

Getu E, 1996. Cottony cushion scale infestation on acacia trees. IAR Newsletter of Agricultural Research, 11(2):11

Haas J, 1993. Effect of saline irrigation on early growth of Eucalyptus gomphocephala and Acacia saligna. Environmental Conservation, 20(2):143-148, 162; 15 ref

Hadjikyriakou G, Hadjisterkotis E, 2005. The adventive plants of Cyprus with new records of invasive species. Zeitschrift für Jagdwissenschaft, 48(1):59-71

Hall N, Turnbull JW, 1976. Acacia saligna (Labill.) H. Wendl. formerly known as A. cyanophylla Lindl. [Orange wattle, blue-leafed wattle]. Australian Acacias, Division of Forest Research, CSIRO, Australia, No. 4, 2 pp.; 7 ref

Hall PE, 1939. Notes on the analyses of certain South African woods with special reference to their use as a producer gas generator fuels. Journal of the Chemical, Metallurgical and Mining Society of South Africa, 40:350-352

Henderson L, 2001. Alien weeds and invasive plants. Cape Town, South Africa: Plant Protection Research Institute, Agricultural Research Council, 300 pp

Holmes PM, 2002. Depth distribution and composition of seed-banks in alien-invaded and uninvaded fynbos vegetation. Austral Ecology, 27(1):110-120

House S, Nester M, Taylor D, King J, Hinchley D, 1998. Selecting trees for the rehabilitation of saline sites. Technical Paper 52. Queensland Department of Primary Industries

Hussain A, Gul P, 1993. Selection of suitable tree species for saline and waterlogged areas in Pakistan. In: Davidson N, Galloway R, eds. Productive use of saline land. ACIAR Proceedings 42:53-55

ILDIS, 2007. International Legume Database and Information Service. Reading, UK: School of Plant Sciences, Unversity of Reading. http://www.ildis.org/

Jones TC, Batchelor CA, Harris PJC, 1990. In vitro culture and propagation of Acacia species (A. bivenosa, A. holosericea, A. salicina, A. saligna and A. sclerosperma). International Tree Crops Journal, 6(2-3):183-192; 17 ref

Kairo M, Ali B, Cheesman O, Haysom K, Murphy S, 2003. Invasive species threats in the Caribbean region. Report to the Nature Conservancy. Curepe, Trinidad and Tobago: CAB International, 132 pp. http://www.issg.org/database/species/reference_files/Kairo%20et%20al,%202003.pdf

Karaca I, Senal D, Colkesen T, ÷zg÷kce MS, 1999. Observations on the oleander scale, Aspidiotus nerii BouchT (Hemiptera: Diaspididae) and its natural enemies on blueleaf wattle in Adana Province, Turkey. Entomologica, 33:407-412; 5 ref

Kessy BS, 1987. Growth of Australian acacias in Tanzania. ACIAR Proceedings, Australian Centre for International Agricultural Research, No. 16:123-125

Langkamp PJ, 1987. Germination of Australian native plant seed. Melbourne, Australia: Inkata Press

Le Houérou HN, 2002. Multipurpose germplasm of fodder shrubs and trees for the rehabilitation of arid and semi-arid land in the Mediterranean isoclimatic zone. A photograph catalogue. In: Options Méditerranéennes, Series B Paris, France: CIHEAM, 21-29

Lyons A, Majer J, 1999. The value of farm alleys as refugia for beneficial arthropods. Proceedings of the 7th Australasian Conference on Grassland Invertebrate Ecology., 165-176; 18 ref

Majer JD, 1979. The possible protective function of extrafloral nectaries of Acacia saligna. Annual Report 1978, Mulga Research Centre, Australia, 31-39; 9 ref

Marcar NE, Crawford DF, Leppert PL, Jovanovic T, Floyd R, Farrow R, 1995. Trees for saltland: a guide to selecting native species for Australia. Melbourne, Australia: CSIRO

Marchante E, Marchante H, 2005. No. 20, Acacia saligna (Labill.) H. L. Wendl. Plants invasoras em Portugal. Coimbra, Portugal: Project Invader, University of Coimbra. http://www1.pt/invasoras/files/20acacia_saligna.pdf

Martin V, 1974. Dyemaking with Australian Flora. Rigby: Adelaide, Australia

Maslin BR, 1974. Studies in the genus Acacia. 3: The taxonomy of A. saligna (Labill.) H. Wendl. Nuytsia, 1:332-340

McDonald MW, Maslin BR, Thomson LAJ, 2002. Domestication of wattles with edible seeds for the wheatbelt of Western Australia. Conservation Science Western Australia, 4(3):170-180

Melland RL, Virtue JG, 2002. Weed risk assessment of twenty plant species used for revegetation or farm forestry in South Australia. In: 13th Australian Weeds Conference: weeds "threats now and forever?", Sheraton Perth Hotel, Perth, Western Australia, 8-13 September 2002: papers and proceedings Victoria Park, Australia: Plant Protection Society of Western Australia Inc, 51-54

Michaelides ED, 1979. Mini-monograph on Acacia cyanophylla. Technical Consultation on Fast-Growing Plantation Broadleaved Trees for Mediterranean and Temperate Zones. Lisbon, Portugal, 16-20 October 1979. Rome, Italy: FAO

Morris MJ, 1999. The contribution of the gall-forming rust fungus Uromycladium tepperianum (Sacc.) McAlp. to the biological control of Acacia saligna (Labill.) Wendl. (Fabaceae) in South Africa. Biological control of weeds in South Africa (1990-1998)., 125-128; [^italic~African Entomology Memoir^roman~, No. 1]; 11 ref

Nakos G, 1977. Acetylene reduction (N2-fixation) by nodules of Acacia cyanophylla. Soil Biology and Biochemistry, 9(2):131-133; 12 ref

National Academy of Sciences, 1980. Firewood Crops: Shrub and Tree Species for Energy Production. Washington DC, USA; National Academy of Sciences

Orchard AE, Maslin BR, 2003. Proposal to conserve the name Acacia Mill. (Leguminosae: Mimosoideae) with a new type. Taxon, 52:362-363

Pedley L, 1986. Derivation and dispersal of Acacia (Leguminosae), with particular reference to Australia, and the recognition of Senegalia and Racosperma. Botanical Journal of the Linnean Society, 92(3):219-254; 143 ref

PIER, 2007. Pacific Islands Ecosystems at Risk. USA: Institute of Pacific Islands Forestry. http://www.hear.org/pier/index.html

Ramadan D, 1957. A note on the nutritive value of Acacia cyanophylla seeds. Emp. J. exp. Agric. 25 (97), (37-9). 2 refs

Reddell P, Warren R, 1987. Inoculation of acacias with mycorrhizal fungi: potential benefits. ACIAR Proceedings Series, Australian Centre for International Agricultural Research, No. 16:50-53

Roughley RJ, 1987. Acacias and their root-nodule bacteria. In: Turnbull JW, ed. Australian Acacias in Developing Countries. ACIAR Proceedings, 16:45-49

Roux ER, Middlemiss E, 1963. Studies in the autecology of the Australian Acacias in South Africa. I. The occurrence and distribution of Acacia cyanophylla and A. cyclops in the Cape province. South African Journal of Science, Johannesburg 59 (6), (286-94). 7 refs

Ruskin FR, Eckholm E, 1980. Firewood crops. Shrub and tree species for energy production. 1980, xi + 237 pp. Washington DC, USA: National Academy Press

Ryan PA, Bell RE, 1989. Growth, coppicing and flowering of Australian tree species in southeast Queensland, Australia. ACIAR Monograph, No. 10:49-68; [refs. at end of book]

Ryan PA, Bell RE, 1991. Australian hardwoods for fuelwood and agroforestry. Review report on ACIAR Project 8809. Gympie: Queensland Forest Service (unpublished)

Sale GN, 1948. Note on sand dune fixation in Palestine. Emp. For. Rev. 27 (1), (60-1 + 4 photos)

Sanz-Elorza M, Dana E, Sobrino E, 2001. Checklist of invasive alien plants in Spain (Iberian Peninsula and Balearic Islands). Lazaroa, 22:121-131; many ref

Scheltema M, 1992. Direct seeding of trees and shrubs. Perth, Australia: Greening Western Australia

Selincourt Kde, 1992. South Africa's other bush war. New Scientist, 133(1808):46-49

Simmons MH, 1981. Acacias of Australia. 325 pp. Melbourne, Australia: Nelson

Stanley TD, Ross EM, 1983. Flora of south-eastern Queensland. Vol. 1. Brisbane: Queensland Government, Dept of Primary Industries

Stirton CH, 1980. Plant invaders: beautiful, but dangerous. Dept. of Nature and Environmental Conservation of the Provincial Administration, Cape Town, South Africa

Strassen RZ, Halperin J, 1990. New records of Thysanoptera from Israel. Israel Journal of Entomology, 24:17-20

Swailem SM, Awadallah KT, Shaheen AA, 1980. Abundance of Lindingaspis rossi Mask. On ornamental host plants in Giza and Zagazig regions, Egypt (Hemiptera-Homoptera: Diaspididae). Bulletin of the Entomological Society of Egypt, 60:257-263

Theron JM, Laar Avan, Kunneke A, Bredenkamp BV, 2004. A preliminary assessment of utilizable biomass in invading Acacia stands on the Cape coastal plains. South African Journal of Science, 100(1/2):123-125

Tilstone GH, Pasiecznik NM, Harris PJC, Wainwright SJ, 1998. The growth of multipurpose tree species in the Almeria province of Spain and its relationship to native plant communities. International Tree Crops Journal, 9(4):247-259; 41 ref

USDA, NRCS, 2007. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Vercoe TK, 1989. Fodder value of selected Australian tree and shrub species. ACIAR Monograph, No. 10:187-192; [refs. at end of book]

Vercoe TK, McDonald MW, 1987. Seed collections of salt tolerant woody plant species in Australia. National Biotechnology Program. Australian Tree Seed Centre

Whibley DJE, Symon DE, 1992. Acacias of South Australia. Revised 2nd edn. Handbook of the flora and fauna of South Australia. Adelaide: South Australian Government Printer

Witt, A., Luke, Q., 2017. Guide to the naturalized and invasive plants of Eastern Africa, [ed. by Witt, A., Luke, Q.]. Wallingford, UK: CABI.vi + 601 pp. http://www.cabi.org/cabebooks/ebook/20173158959 doi:10.1079/9781786392145.0000

Wood AR, Morris MJ, 2007. Impact of the gall-forming rust fungus Uromycladium tepperianum on the invasive tree Acacia saligna in South Africa: 15 years of monitoring. Biological Control, 41(1):68-77. http://www.sciencedirect.com/science/journal/10499644

Woodward A, Reed JD, 1989. The influence of polyphenolics on the nutritive value of browse: a summary of research conducted at ILCA. ILCA Bulletin, No. 35:2-11; 50 ref

Yelenik SG, Stock WD, Richardson DM, 2004. Ecosystem level impacts of invasive Acacia saligna in the South African fynbos. Restoration Ecology, 12(1):44-51

Yelenik SG, Stock WD, Richardson DM, 2007. Functional group identity does not predict invader impacts: differential effects of nitrogen-fixing exotic plants on ecosystem function. Biological Invasions, 9(2):117-125. http://www.springerlink.com/content/55j27w7k41794246/?p=6a1bd53b63544519b4d28bf5c296fbd7&pi=2

Contributors

Top of page

10/01/2008 Updated by:

Nick Pasiecznik, Consultant, France

Distribution Maps

Top of page
You can pan and zoom the map
Save map