NORTHERN BLACK WATTLE

Description

This tree is native to the savannas of Papua New Guinea and tropical northern Australia. It has been widely introduced in Fiji, India, Indonesia, Java, Malaysia, Niger, Nigeria, Philippines, Tanzania, Thailand, the Soloman Islands, Uganda, and Zanzibar. A low to medium-sized fast growing deciduous or evergreen tree with bright yellow flowers. The tree can reach a height of 8-30 m (26-100 ft) and a trunk diameter of up to 60 cm (24 in). The tree fixes nitrogen and regenerates rapidly. This acacia has the ability to live for up to 20 years on soil contaminated with uranium spoils.

Uses

As a tree, it is useful for fuel wood, as an ornamental and as a shade tree. The wood is used in making farm tools and furniture. The tannin from A. auriculiformis is used in tanning leather and to redden it as it is exposed to sunlight. It is utilized to reclaim mining lands, rehabilitate eroded soils, for reforestation and for shade as an ornamental.

Cultivation

•  Elevation: 0-600 m (0-2000 ft)
•  Soil: tolerates soil that is compacted, unstable, alkaline, acidic, waterlogged or dry
•  Rainfall: can survive a dry season of 120-240 days
•  Germination: best if soaked for 24 hours before planting
•  Latitudinal range: 7-20°S It occurs naturally in coastal lowlands, in closed forests along streams, in low open forests and savannas, adjacent to mangroves, or behind beaches. It can grow on step slopes. Branches break easily in storm winds and the tree is not very fire resistant

Harvesting and Seed Production

Northern Black Wattle can grow to 20 m (65 ft) in a ten year rotation. Seeds can be stored for 18 months if kept from exposure to air. Trees copice poorly. When trees are felled, there is usually a swarm of seedlings, so cutover stands regenerate readily. Optimum annual wood production is 10-20 m³/ha.

Pests and Diseases

To date, there have not been reported serious pests or diseases in A auriculiformis. In nurseries and young stands in Indonesia there has been found: a fungal disease caused by Uromyces digitatus that affects growth, root rot by Ganoderma lucidum and G. applanatum, and powdery mildew caused by Sphaeroteca spp. In India there have been problems with a weevil Hypomeces squamosus and in Australia with borers and termites which damage the lumber. Zanzibar has reported some insect and nematode damage to seedlings.