The Mountain ash (Eucalyptus regnans) of southern Australia is the tallest of all flowering plants, and possibly once the tallest of all plants — although the tallest specimens have all been destroyed by humans. The largest remaining specimen is 92 metres high; old records of logged trees make varied claims up to 131 metres (430 feet), though little creedence is given to these claims. Mountain ash is a straight, grey-trunked tree, smooth-barked for all but the first few metres, and is native to cool, deep soiled, mostly mountainous areas to 1000m in Victoria and Tasmania with very high rainfall of over 1200mm (47 inches) per year.

Unusually for a Eucalypt, it cannot usually recover by re-shooting after fire, and can only regenerate from seed. In the long term occasional fires (such as the naturally ignited blazes thought to occur about every 200-400 years on average) do not severely impact Mountain ash forest but, because it takes roughly twenty years for seedlings to reach sexual maturity, repeated fires in the same area can wipe stands out.

Mountain ash is valued for its timber, not so much because of any particular virtue of the timber itself (it is a heavy, fine-grained eucalyptus hardwood much like several others), but because of the sheer volume that can be harvested. Primary uses are sawlogging and woodchipping . Very few natural stands of Mountain-ash remain, but substantial areas of regrowth exist, and it is sometimes grown in plantations.

Great controversy surrounds its use: as the largest eucalypt of all it has symbolic value to conservationists, it provides essential habitat to important birds and mammals (notably the Lyrebird and the endangered Victorian state animal emblem Leadbeater's Possum), and in a land of vast, relatively arid plains, the contrasting lush fertility of Mountain-ash forest is particularly dear to nature lovers. Although the status of E. regnans as a species is secure, political opposition to logging it has grown very strong in recent years (particularly in the case of woodchipping), and the extent of future harvesting remains uncertain.

See also

• Eucalyptus
• Eucalyptus delegatensis
• Manna Gum
• Messmate Stringybark
• For other trees named Mountain Ash, see Mountain ash

References

• Forestry Tasmania The tallest Eucalyptus regnans measured as 92 m in 2000 (.pdf file)
• Association of Societies for Growing Australian Plants: Eucalyptus regnans
• Victorian Eucalypts: Eucalyptus regnans