Eucalyptus regnans
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 Known as "El Grande", about 80 metres, was the most massive, though not tallest, Eucalyptus regnans. Accidentally killed, 2002, by loggers burning-off after felling old-growth forest around it.
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| Eucalyptus regnans F.Muell. |
Eucalyptus regnans, known variously by the common names Mountain Ash, Victorian Ash, Tasmanian Oak or Stringy Gum, is a species of Eucalyptus native to southeastern Australia, in Tasmania and Victoria.
It is an evergreen treethe tallest of the eucalypts, growing to 70-90 m, with a straight, grey trunk, smooth-barked except for the rough basal 5-15 metres. The leaves are falcate (sickle-shaped) to lanceolate, 9-14 cm long and 1.5-2.5 cm broad, with a long acuminate apex and smooth margin, green to grey-green with a reddish petiole. The flowers are produced in clusters of 9-15 together, each flower about 1 cm diameter with a ring of numerous white stamens. The fruit is a capsule 5-9 mm long and 4-7 mm broad.
It occurs in cool, deep soiled, mostly mountainous areas to 1000 m altitude with high rainfall of over 1200 mm per year. They grow very quickly, at more than a metre a year, and can reach 65 metres in 50 years. They can live for about 400 years. The fallen logs continue supporting a rich variety of life for centuries more on the forest floor.
Unusually for a eucalypt, it tends not to recover by re-shooting after fire, and regenerates mainly from seed. Severe fires can kill all the trees in a forest, prompting a massive release of seed to take advantage of the nutrients in the ash bed. Seedling densities of up to 2.5 million per hectare have been recorded after a major fire. Competition and natural thinning eventually reduces the mature tree density to about 30 to 40 individuals per hectare. Because it takes roughly 20 years for seedlings to reach sexual maturity, repeated fires in the same area can cause local extinctions.
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[edit] Tallest specimens
Eucalyptus regnans is the tallest of all flowering plants, and possibly once the tallest of all plants. The tallest measured specimen is officially taken as 114.3 metres. The tree, Cornthwaite Tree or Thorpdale Tree, was first measured by theodolite in 1880. Next year it was felled and then measured by tape and there was close agreement. (Ken J. Simpfendorfer. "Big Trees in Victoria"). The stump commemorated with an insignificant plaque that exists today. The tree was about 1 metre shorter than the world's current tallest living tree, a Coast Redwood, 115.55 metres. The tallest specimens encountered by early European settlers are now dead as a result of bushfires, logging and advanced age. The tallest measured living specimen, Icarus Dream, was rediscovered in Tasmania in January, 2005 and is 97 metres high (Tasmanian Giant Trees Consultative Committee, ref. 1). It was first measured by surveyors at 98.8 metres in 1962 but the documentation had been lost. 15 living trees in Tasmania have been reliably measured in excess of 90 metres (Tasmanian Giant Trees Consultative Committee, ref. 3). Few living specimens in Victoria exceed 90 metres; old records of logged trees make varied claims of extreme heights, but these are difficult to verify today. The famous Ferguson Tree, a specimen in Victoria that fell after a bushfire, was measured by tape by a government surveyor, William Ferguson, on 21 February 1872, at 133 metres (436 feet), though this figure is not now generally accepted. Its crown had broken off and the diameter of the trunk at that point was still one metre, leading to claims that when it was intact the tree would have exceeded 150 metres (500 feet); this however presupposes that the break occurred in a hitherto undamaged tree. A more realistic scenario is of a shorter tree with several episodes of breakage and regrowth building up a stout stem without at any time attaining the claimed height.
[edit] Uses
Eucalyptus regnans is valued for its timber, and has been harvested in very large quantities. Primary uses are sawlogging and woodchipping. It was a major source of newsprint in the 20th century. Much of the present woodchip harvest is exported to Japan. While the area of natural stands with large old trees is rapidly decreasing, substantial areas of regrowth exist and it is increasingly grown in plantations, the long, straight, fast growing trunks being much more commercially valuable than the old growth timber. It is a medium weight (about 680 kg/m3) timber and rather coarse (stringy) in texture. Gum veins are common. The wood is easy to work and the grain is straight with long, clear sections and almost no knots. The wood works reasonably well for steam-bending. Primary uses for sawn wood are furniture, flooring (where its very pale blonde colour is highly prized), panelling, veneer, plywood, window frames, general construction. The wood has sometimes been used for wood wool and cooperage. However, the wood needs steam reconditioning for high value applications, due to a tendency to collapse on drying. This wood is highly regarded by builders, furniture makers and architects. [1]
[edit] Conservation
Great controversy surrounds the logging of old-growth Eucalyptus regnans in its natural range in both Victoria and Tasmania. Aside from its symbolic significance as the largest eucalypt of all, Eucalyptus regnans has value to conservationists in provides essential habitat to important birds and mammals (notably the Wedge tailed eagle, the Lyrebird and the endangered Victorian state animal emblem Leadbeater's Possum). In a land of vast, arid plains and desert, the contrasting lush fertility of mountain-ash forest is particularly dear to nature lovers.
Although its status as a species is secure, old-growth forests of Eucalyptus regnans are particularly susceptible to destruction by fire. For this reason stands of very old and very tall trees exist only in pockets. Very few such stands of trees fall within those areas that have been listed as National Park or World Heritage Environments. Most lie within areas controlled by state forestry management authorities and their heritage value is balanced against the commercial value of harvesting and then planting fast-growing and more productive timber crops on these comparatively well-watered areas.
Political opposition to the logging of old-growth forests by the process known as clearfelling has grown very strong in recent years (particularly in the case of woodchipping), and the extent of future harvesting remains uncertain. This is controversial, because the nature of its re-growth habit requires open space, and an ash layer[2]. Studies conducted in the Twentieth Century suggest that clearfelling is essential to the successful germination and growth of seedlings[3]. This clearfell process can lead to spectacular and uniform regrowth if managed appropriately. However this method has often been used to justify the unreasonable exploitation of a lucrative resource in certain areas. The clearfell process was however unavailable until the arrival of white settlers (indigenous people practiced a mozaic burn system that kept the forest open but didn't remove or clearfell large amounts of timber[4]) and the usual method of regrowth was through intense bushfire that catastrophically destroyed the forest allowing the regrowth process.
[edit] See also
- Eucalyptus delegatensis
- Manna Gum
- For other trees named Mountain Ash, see Mountain ash
[edit] References
- Tasmanian Giant Trees Consultative Committee New Tallest Tree for Tasmania 2005
- Forestry Tasmania The tallest Eucalyptus regnans measured as 92 m in 2000 (.pdf file)
- Tasmanian Giant Trees Consultative Committee Tasmania's Ten Tallest Giants 2006
- Association of Societies for Growing Australian Plants: Eucalyptus regnans
- Victorian Eucalypts: Eucalyptus regnans
- International Society of Arboriculture, Australia Chapter: Australia's Biggest, Tallest and Oldest Trees
- "Wood in Australia" by Keith R Bootle
[edit] Gallery
 The Styx River in Tasmania runs through a forest of Eucalyptus regnans, Myrtle and tree ferns. |
 "The Big Tree" see above, is about 15 metres around the base. |
 Clearfelled old-growth forest of Eucalyptus regnans near the Styx Valley in southern Tasmania |
 One of the remaining very tall Mountain Ash by a logging road. A number of trees of extreme size have been recorded by Forestry Tasmania as worthy of preservation. |
 The stump of one of the largest Eucalyptus regnans to be logged in Tasmania. |
 Mountain Ash Logs. Older trees are often hollow and are only suitable for woodchip. |
 The efficient harvesting of Eucalyptus regnans for replacement with Pinus radiata. |
 High grade woodchip for the papermills of Japan is exported from Burnie |
