Classification of the genus Acacia (in the wider sense) has been subject to considerable debate. It is generally agreed that there are valid reasons for breaking it up into several distinct genera, but there has been disagreement over the way this should be done. As of 2017, it is widely (but not completely) accepted that the section that includes the majority of the Australian species (including this one) should retain the name Acacia, whilst other sections of the genus should be transferred to the genera Acaciella, Mariosousa, Senegalia and Vachellia[].
Closely related to Acacia auriculiformis, often forming hybrids with it in the wild[].

Common Name:

General Information

Acacia mangium is a fast-growing evergreen tree with a dense, spreading crown; it can grow from 25 - 35 metres tall[]. The bole is usually straight, often fluted near the base, free of branches for up to half its height and up to 60cm in diameter[, ]. Although it produces leaves as a seedling, llike most members of the genus the mature plant does not have true leaves but has leaf-like flattened stems called phyllodes[].
The tree is harvested from the wild for its wood, which is used locally and also traded. It is valued for its rapid growth and ability to grow on poor soils, and has been planted throughout the humid tropics and is a major plantation species in Asia[, ]. The tree is also grown as an ornamental in some areas[].

Known Hazards

The seed of many Acacia species, including this one, is edible and highly nutritious, and can be eaten safely as a fairly major part of the diet. Not all species are edible, however, and some can contain moderate levels of toxins[]. Especially when harvesting from the wild, especial care should be taken to ensure correct identification of any plants harvested for food[].
Especially in times of drought, many Acacia species can concentrate high levels of the toxin Hydrogen cyanide in their foliage, making them dangerous for herbivores to eat.

Botanical References

Range

Australia - Queensland, north to Papua New Guinea and Indonesia.

Habitat

Primary and secondary forest, savannah, regrowth of woodland and savannah, open grassland, poorly drained flood plains, behind mangroves in seasonal swamps, sometimes dominant; at elevations up to 195 metres[, ].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	25.00 m
Growth Rate	Fast
Pollinators	Insects
Self-fertile	Yes
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

A plant of the warm humid tropics, it is found at elevations up to 800 metres in areas where the mean annual rainfall is in the range of 1,500 - 3,000mm[]. It can tolerate a mean annual rainfall of 1,000 - 4,500 mm[]. Although it survives long dry seasons, growth is greatly reduced[]. Plants do not tolerate frost[].
Succeeds in a wide variety of soil types, usually being found in acid soils of medium-to-low fertility[]. Prefers a well-drained soil, but succeeds in poorly drained conditions[, ]. Prefers a pH in the range 4.5 - 6.5, soils with a high pH are not tolerated[, ]. Requires a sunny position[].
Widely planted in the humid tropics, it has escaped from cultivation in many areas and is viewed as a possible threat to local ecosystems[].
A fast-growing tree, in some plantations it can increase in height by 1.5 - 5 metres per year for each of the first 3 years, before the rate of growth decreases[]. In other plantations annual height increases of 1 - 2 metres and 1 - 3 cm of diameter growth per year are more usually obtained[].
Trees can reach a height of 23 metres, with a bole 23cm in diameter, within 9 years from seed[].
The tree flowers precociously, and viable seed can be harvested 24 months after planting[]. From the onset of flower buds to pod maturity is about 6 - 7 months[].
Regeneration through coppicing or pollarding is poor[].
A short-lived tree, usually dying after 30 - 50 years[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

The germinating seeds can be cooked and eaten as a vegetable[].

Medicinal

The bark of all Acacia species contains greater or lesser quantities of tannins and are astringent. Astringents are often used medicinally - taken internally, for example. they are used in the treatment of diarrhoea and dysentery, and can also be helpful in cases of internal bleeding. Applied externally, often as a wash, they are used to treat wounds and other skin problems, haemorrhoids, perspiring feet, some eye problems, as a mouth wash etc[, ].
Many Acacia trees also yield greater or lesser quantities of a gum from the trunk and stems. This is sometimes taken internally in the treatment of diarrhoea and haemorrhoids[].

Agroforestry Uses:

The tree is planted primarily for site rehabilitation[]. Its quick growth and dense shade make it an effective tool in reforesting Imperata grass swards and reducing fire risk[]. Its ability to grow well on infertile soils, especially those low in phosphorus, make it a favourite for rehabilitation of mine spoils and eroded sites[].
Seedlings and cuttings are planted as initial shade for cocoa in the nurseries or on-farm. Because of its nitrogen-fixing abilities, it is also used in rehabilitating old cocoa farms or on improved fallows intended for cocoa cultivation[].

Other Uses

The tree has high tannin content (18-39%), justifying commercial exploitation of tannins[]. Bark harvested for its tannins should only be taken from mature stems, and only when the sap is rising at the beginning of the growing season - which is when the tannin content is highest and the bark is most easily removed from the wood[].

The heartwood is yellow-brown, sometimes with olive-brown streaks; it is clearly demarcated from the cream-coloured sapwood. The texture is medium; the grain straight. The wood is light in weight; hard to soft; of low durability being susceptible to dry wood borers and termites and moderately susceptible to fungi. It seasons rapidly but with a high risk of distortion and checking; once dried it is stable in service. The wood works well with ordinary tools; nailing and screwing are poor; gluing is best carried out with phenol resins. It is suitable for construction, boat building, furniture and cabinet making, particleboard, plywood, veneer and fenceposts[, , ].
The tree is widely grown to provide pulp for the paper industry[]. The pulp is readily bleached to high brightness levels and is excellent for papermaking. The neutral sulphite semi-chemical pulping of Acacia mangium gives yields of 61 - 75%[].
The wood is used for fuel[]. With a calorific value of 4,800-4,900 kcal/kg, the tree provides good quality charcoal and is suitable for the manufacture of charcoal briquettes and artificial carbon[].

Propagation

Seed - pre-treatment is necessary to break the hard seed coat. To encourage uniform germination, seed should be scarified either by submerging in boiled water that is allowed to cool for 24 hours, or by soaking in sulphuric acid for 10-30 minutes followed by soaking in cool water for 24 hours[]. The visibly swollen seeds should be sown immediately[]. Germination, which is normally around 60 - 80&, usually starts after one day and continues for 10 - 15 days[]. Young seedlings are potted up when large enough to handle, and can be planted out when 25cm tall, usually after about 16 weeks[].
The seed can retain its viability for several years when stored at room temperature in a dark place in a sealed container[].
Air-layering.
Single-node stem cuttings 4 - 5 cm long and 0.5 - 1.5 cm in diameter, leaving 0.5 - 1 phyllodes[]. The application of indole-butyric acid or rooting powder enables 65-75% rooting; rooting is reported to be slow[].
Grafting

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