Eucalyptus regnans has several common names including Mountain Ash, Stringy Gum, Victorian Ash, Swamp Gum and Tasmanian Oak. Builders, furniture makers and architects all hold the mountain ash in high esteem.
It is one of the tallest tree species in the world and the tallest hardwood species. It can reach a height of 100 metres with a girth exceeding 15 metres at the base. The lowest branches are usually 30 metres above the ground. It is a fast grower and may grow a metre per annum. Some have been known to reach 65 metres in 50 years. The average lifespan is 400 years.
It is native to the cool mountain forests of south-eastern Australia, including Tasmania. Areas such as these have an annual rainfall of around over 1200mm. It likes deep, fertile soil and thrives on sheltered mountain slopes and in protected gullies.
The lower part of the trunk has persistent fibrous bark while further up the trunk the bark sheds into long ribbons to reveal a smooth whitish or grey-green surface. The adult leaves are sickle- to lance-shaped, from 9 to 14cm long and 1.5 to 2.5cm wide and the crown is narrow and open. It produces clusters of small, white flowers in summer. After flowering, woody capsules appear.
E.regnans propagates by seed. Because of the canopy in an established forest, there is insufficient light for successful germination and growth of young plants. Heat from bushfires causes the woody capsules to release the seeds. A major fire results in a huge release of seed and a high density of seedlings. This density reaches more viable levels through competition and natural thinning.
The mountain ash is an evergreen tree and has long been prized for its hard, durable timber. During the 20th century, it was a major source of newsprint. Woodchipping and sawn timber have also been important products from the mountain ash. It is now grown in plantations where its long, straight trunks plus speed of growth has made it commercially valuable. The timber is rather coarse in texture, easy to work with a long, straight grain. Its pale blonde colour is highly valued for flooring. It is also used for panelling, plywood for packing cases, veneer, window frames, furniture and general construction work.
In its native areas, the mountain ash has high importance in providing habitat for birds and mammals. Several species of acacia are commonly found under the canopy. Smaller trees, shrubs and tree ferns form the next layer (up to 15 metres). Forest grasses, bracken and shade- and damp-loving plants are found on the forest floor. Such varied and dense layers of vegetation provide all manner of food for many species of birds and animals.
In Tasmania, the majority of old growth E.regnans forests have been felled and clearfelling continues.
With its great height and girth, the mountain ash is certainly one of the forest’s giants.