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Bendoc, Vic.

Errinundra, Vic.  

Ben Lomond, NSW

Natural populations

Acacia dealbata comprises two subspecies [1,2,3]:

Subsp. dealbata is commonly a large shrub or medium-sized tree with an erect main stem 6–15 m tall, but attains heights of 25–28 m in the far south of its range in Tasmania and Victoria. Subsp. subalpina is a smaller plant, up to 3 m tall.

Flowering and seeds

Flowering occurs mainly during August to October but can extend from July to November [1,2,3,4]. From flowering it takes about 5-6 months for seed pods to mature, which is mainly during December to February. Seeds remain viable in the ground for many years. There are about 50 viable seeds per gram [4]. Nicking or boiling the seeds in water for a minute at 100°C is required to induce germination. The seeds start to germinate in about 6 days if grown at 25°C [4].

Cultivation and uses

This is a fast growing, cold tolerant species has been used to control soil erosion, hillside stabilisation, gully erosion control and in windbreaks [2,3]. It is best suited to cultivation in moderate to high rainfall areas of temperate Australia. This species increases nitrogen levels in the soil due to the fixation of atmospheric nitrogen by its roots and via breakdown of its leaf litter fall. Provenance variation in growth performance, insect resistance and frost tolerance is considerable [3]. The wood of this species is used for pulpwood in Tasmania and has good gluing properties, which makes it amenable for wood composite products [1]. The bark yields 16-36% tannin, while the gum produced from wounds in the bark has potential as a gum arabic substitute [3]. This gum is also an important source of winter carbohydrate for arboreal petaurid marsupials [2]. Acacia dealbata is grown in southern Europe where it is known as 'mimosa' and is used commercially in the cut flower trade. In France, the flowers are used as a fixative in high grade perfume production. It has become a weed in numerous areas where it has been grown.

Key descriptors for subsp. dealbata :
Climate parameters
Mean annual rainfall: 500-1600 mm
Rainfall distribution pattern: summer, uniform or winter
Mean annual temperature: 5-17 °C
Mean max. temperature of the hottest month: 16-30 °C
Mean min. temperature of the coldest month: -3-7 °C
Frosts per year: up to 20 or greater than 20
Frost intensity: light to moderate (0 to -5°C) or heavy (greater than -5°C)
Altitude: 5-1000 metres
Tolerance of climate extremes
Drought: known to be drought sensitive
Fire: killed by damaging fire does not regenerate foliage
Frost: tolerates frosts in the 0° to -5°C range or tolerates heavy frosts colder than -5°C
Soil factors

Texture: clay loam, heavy clay (greater than 50% clay), light to medium clay (35-50% clay) or loam, sandy loam, sandy clay loam
Soil pH reaction: acidic (less than 6.5) or neutral (6.5-7.5)
Soil depth: moderate to deep (30-100 cm or greater)
Drainage: well-drained
Salinity: non-saline
Tolerance of adverse soils
Extremes in pH: acidity
Extremes in texture: clayey
Salinity: nil - sensitive to saline soils
Soil waterlogging tolerance: nil - sensitive to waterlogged soils
Biological traits under cultivation

Habit: tree 5-10 m tall or sometimes a tree 10-20 m tall, usually produces a clear trunk
Longevity: short-lived less than 15 years (but sometimes longer)
Growth rate: fast
Coppicing ability: nil or negligible
Erosion control potential: excellent for clayey sites or excellent for sandy sites
Growth rate: fast
Root system: moderate to deep, shallow and spreading, fixes nitrogen via root symbiot
Wood density: low (less than 600 kg/cubic metre) or mod. to high (greater than 600 kg/cubic metre)
Carbon sequestration potential: moderate
Uses
Specialty products: pollen has value in apiculture, high tannin content in bark, foliage, fruits have potential for floriculture or produces oils used in perfumery
Urban use: good as an ornamental or amenity plant
Wood products: pulpwood (wood chips for paper pulp), panelling or speciality timber for quality furniture, medium density fibreboard, oriented strand board, plywood, wood veneer or laminated veneer lumber or wood wool/wood cement
Potentially undesirable attributes
Fire sensitivity: killed by severe fires (seeder)
Growth habit: mod. to strong propensity to root sucker or shallow roots may outcompete adjacent plants
Weediness: listed at least once as a declared weed species or high potential based on its biology

Key descriptors for subsp. subalpina:
Climate parameters
Mean annual rainfall: 600-700 mm
Rainfall distribution pattern: uniform or winter
Mean annual temperature: 5-18 °C
Mean max. temperature of the hottest month: 23-25 °C
Mean min. temperature of the coldest month: -6-0 °C
Frosts per year: up to 20 or greater than 20
Frost intensity: heavy (greater than -6°C)
Altitude: 1000-1550 metres
Tolerance of climate extremes
Drought: known to be drought sensitive
Fire: killed by damaging fire does not regenerate foliage
Frost: tolerates frosts in the 0° to -5°C range or tolerates heavy frosts colder than -5°C
Soil factors

Texture: clay loam, heavy clay (greater than 50% clay), light to medium clay (35-50% clay) or loam, sandy loam, sandy clay loam
Soil pH reaction: acidic (less than 6.5) or neutral (6.5-7.5)
Soil depth: skeletal to shallow (less than 30 cm) or moderate to deep (30-100 cm or greater)
Drainage: well-drained
Salinity: non-saline
Tolerance of adverse soils
Extremes in pH highly acidic
Extremes in texture very clayey
Salinity nil - sensitive to saline soils
Soil waterlogging tolerance nil - sensitive to waterlogged soils
Biological traits under cultivation

Habit: shrub less than 2 m tall, multi-stemmed from or near ground level
Longevity short-lived less than 15 years
Growth rate fast
Coppicing ability nil or negligible
Erosion control potential excellent for clayey sites or excellent for sandy sites
Root system: moderate to deep, shallow and spreading, fixes nitrogen via root symbiot
Wood density low (less than 600 kg/cubic metre) or mod. to high (greater than 600 kg/cubic metre)
Carbon sequestration potential: moderate
Uses
Specialty products: pollen has value in apiculture; foliage, fruits have potential for floriculture
Urban use: good as an ornamental or amenity plant
Potentially undesirable attributes
Fire sensitivity: killed by severe fires (seeder)
Growth habit: mod. to strong propensity to root sucker or shallow roots may outcompete adjacent plants
Weediness: high potential based on its biology

Key descriptors for the Corangamite provenance:

Climate parameters
Mean annual rainfall 800-900 mm
Rainfall distribution pattern uniform or winter
Frosts: frost free or more or less frost free
Frost intensity: frost free
Mean annual temperature 10-16 °C
Mean max. temperature of the hottest month 20-21 °C
Mean min. temperature of the coldest month 7-8 °C
Altitude: 0-50 metres
Tolerance of climate extremes
Drought: known to be drought sensitive
Fire killed by damaging fire does not regenerate foliage
Frost tolerates frosts in the 0° to -5°C range
Wind tolerates salt-laden coastal winds
Soil factors

Texture: clay loam, loam, sandy loam, sandy clay loam or sand
Soil pH reaction: alkaline (greater than 7.5)
Soil depth: skeletal to shallow (less than 30 cm) or moderate to deep (30-100 cm or greater)
Drainage: well-drained
Salinity: slightly to moderately saline
Tolerance of adverse soils
Extremes in pH: highly alkaline
Extremes in texture: very sandy
Salinity: nil - sensitive to saline soils or slight (2-4 dS m-1)
Soil waterlogging tolerance: nil - sensitive to waterlogged soils
Biological traits under cultivation

Habit: usually produces a clear trunk
Longevity: short-lived less than 15 years
Growth rate: fast
Coppicing ability: nil or negligible
Erosion control potential: excellent for clayey sites or excellent for sandy sites
Windbreak potential: tolerates salty coastal winds
Root system: fixes nitrogen via root symbiot
Wood density: low (less than 600 kg/cubic metre) or mod. to high (greater than 600 kg/cubic metre)
Carbon sequestration potential: moderate
Uses

Specialty products apiculture: pollen has value or foliage, fruits have potential for floriculture
Urban use: good as an ornamental or amenity plant
Wood products: pulpwood (wood chips for paper pulp), panelling or speciality timber for quality furniture, wood composites
Potentially undesirable attributes
Fire sensitivity: killed by severe fires (seeder)
Growth habit: mod. to strong propensity to root sucker or shallow roots may outcompete adjacent plants
Weediness: listed at least once as a declared weed species, high potential based on its biology

References

[1] Boland DJ, Brooker MIH, Chippendale GM, Hall N, Hyland BPM, Johnson RD, Kleinig DA, McDonald MW, Turner JD (2006) Forest Trees of Australia. CSIRO Publishing, Collingwood.

[2] Maslin BR, McDonald MW (2004) AcaciaSearch-evaluation of Acacia as a woody crop option for southern Australia. Rural Industries Research Development Corporation Publication No. 03/017, Canberra.

[3] Doran JC, Turnbull JW (eds.) (1997) Australian Trees and Shrubs: species for land rehabilitation and farm planting in the tropics. Australian Centre for International Agricultural Research, Canberra [ACIAR books online: http://www.aciar.gov.au/publication/MN024]

[4] Gunn BV (2001) Australian Tree Seed Centre Operations Manual. Internal Publication, CSIRO Australian Tree Seed Centre, ACT. [Online at http://www.ensisjv.com/Portals/0/atsc-opmanualcomplete.pdf  Accessed March 2008]

Internet links

ABRS Species Bank: http://www.environment.gov.au/cgi-bin/species-bank/sbank-treatment2.pl?id=10832

Charles Sturt University's Virtual Herbarium: http://www.csu.edu.au/herbarium/acacdeal.html 

PlantNET National Herbarium of New South Wales: subsp. dealbata: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=in&name=Acacia~dealbata+subsp.~dealbata; subsp. alpina: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=in&name=Acacia~dealbata+subsp.~subalpina

Wikipedia: http://en.wikipedia.org/wiki/Acacia_dealbata

World Wide Wattle: http://www.worldwidewattle.com/speciesgallery/species-intro.php?id=17858 andhttp://www.worldwidewattle.com/infogallery/utilisation/acaciasearch/pdf/dealbata.pdf

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