Acacia mearnsii

Native range: Tas, Vic, ACT, NSW Height: 3-10 m Width: 2-4 m Flowering: Late spring Fruiting: Early summer Light: Semi-shade to full sun Growth rate: Fast Soils: Clay, clay loam and sandy soils Drought tolerance: Moderate Landscape position: Hillsides, creek margins Rainfall range: 700 – 1000 mm Benefits: Black Wattle (Acacia mearnsii) is a short-lived, fast-growing native evergreen small tree, with highly divided feathery, dark green leaves and pale-yellow flowers. Black Wattle fixes nitrogen through a mutual association with Rhizobium bacterium which cause nitrogen fixing nodules to develop on the roots. Its fast growth rate and capacity to increase soil nitrogen levels make it a good mid-level species in shelterbelts. It can be used as a nurse plant by interplanting with slower growing Acacia species or eucalypts. It can be planted in woodlots and in agroforestry. Its fast growth rate and short lifespan make it a useful high turnover timber species. Black wattle is valuable for wildlife habitat. Native insects use the flowers and birds feed on seeds and insects that feed on the nitrogen-rich leaves. It one of the host plants for the Imperial Hairstreak Butterfly (Jalmenus evagoras), which is unusual in having a mutualism with ants which guard the caterpillars and pupae in return for sugar. It is a good addition to gardens and parklands for quick cover, as a nurse tree and as wildlife habitat. In forestry across the globe, A. mearnsii is a chief source of paper pulp, chipboard production and poles. The tannin-rich bark is used as a dyes and adhesives, and the wood fibres used to produce the fabric rayon. Acacia mearnsii is a major forestry species worldwide, especially in South Africa and Brazil, but not in Australia, perhaps due to lacally adapted insect pests. The timber is fine grained, light brown to pinkish brown in colour and will polish to a lustre. It is excellent firewood, burning very hot and producing good coals and charcoal. Drawbacks: Will survive in dry sites but prefers moister sites, especially for wood production. Can get gall infestations and wood boring beetles that produces frass and gum. Uses: Ornamental and landscaping use in parklands and gardens Shelterbelts Habitat for native biodiversity Specialty timber used in cabinetry and fine craft items Timber for firewood Charcoal Propagation: From seed. Weed risk: Low Future climate risks:  Slow growth during extended dry years and heatwaves. Branch dieback, limb drop and death of trees in dry, exposed sites. Increase of disease and insect attack die to uneven climate. References AVH (2022). The Australasian Virtual Herbarium, Council of Heads of Australasian Herbaria –https://avh.chah.org.au Biorich plantations – mimicking nature to integrate conservation & production – https://tinyurl.com/46azfd39 Black wattle for farm forestry – https://tinyurl.com/yhrkt8nv https://shorturl.at/gtT28 PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney – https://shorturl.at/glGV4 The Wood Database – https://shorturl.at/aBIN6