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Acacia mearnsis

Black wattle

Acacia mearnsii drawingOrigin

South and east Australia

Ecology

Annual rainfall: 400-1600mm.

Normal temp range: 2-26C.

Altitude range: up to 2500m.

Seasonal adaptability: 2-3 months dry season and moderate frost resistance.

Soils: well-drained, moist, valley alluvial, forest podzols, sandy loams of acid to neutral pH and low to moderate fertility. Does not do well on calcareous soils.

Light requirement: light-demanding, shade tolerant when older.

Description

Height at maturity: 6-20m.

Diameter at breast height (1.3m) at maturity: 40cm.

Form: short bole with crooked stem and low branching when open growth, straighter in plantation.

Coppicing ability: poor.

Growth: on a good site 1m/year in height and 2.5cm/year in diameter for the first 10 years.

Other: a small to medium-sized evergreen tree with dark fissures bark in older trees. Flower scluster pale yellow and globular, 10-20 clusters per stem, in leaf axis or terminal. Leaves feathery bipinnate, 8-15cm long.

Primary advantages

Nitrogen fixing, fast growth, good fuelwood and tannin source. Suitable for soil protection on poor soils.

Primary disadvantages

Fire sensitive when young, invasive, not windfirm, not suitable for alkaline soils.

Products and yields

Wood products:  fuelwood and charcoal, mine props, poles, low quality pulp. Production 10-25m3/ha/year. Wood density 0.55-0.85.

Fuelwood: 4690-7800 kcal/kg.

Other: bee forage, ornamental, tannin from bark (35-30% tannin).

Propagation

Seedlings, direct seeding, natural regeneration.

Seed treatment

Store dry, cold and airtight. Pretreatment: mechanical scarification, or immerse in boiling water then allow to cool.

Management

Pollarding on 8-10 year rotation. Coppicing is weak.

Agroforestry uses

Shelterbelts, erosion control on poor soils and steep slopes, homegardens, live fence, intercropping when young, pastoral systems, green manure, shade trees for tea.

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