Ironbark After fire

Red Ironbark

Common name Ironbark/ Mugga Ironbark/ Tricarpa
Botanical name Eucalyptus sideroxylon; Eucalyptus tricarpa
Family Myrtaceae
Natural range East coast Australia
Mature height to 20m
Form Upright with bushy crown
Likes Water-logging, frost, poor soils
Dislikes Not much
Where to plant Great flowering feature tree
Known for Rough bark and tough timber

Iron by name; iron by nature

If you were ever wondering how durable a piece of Red ironbark might be in comparison to other timbers, you need only look at the ‘Force’ rating used to categorise wooden beams.

How hard is Red Ironbark?

Radiata Pine, i.e (from plantations) used in conventional house framing has a rating of F7. The ‘F’ stands for ‘force’, and the number refers to the amount of stress – measured in mega pascals – that timber will withstand before it bends too much. So, where Radiata Pine is around F7 and Shining Gum (Eucalyptus nitens) is around F17, freshly-cut defect-free Red Ironbark is rated an impressive F27. This hardness and strength only increases as it dries. It is for this reason that Ironbark beams in old farmhouses and sheds, many decades after they were installed can be viewed almost intact – they’re pretty much bombproof.

How is Ironbark timber harvested?

How fast does Red Ironbark grow? Not fast enough to be used as a plantation timber. These days most Ironbark timber available for sale is either reclaimed from old buildings or harvested from a regrowth forest. A well-managed regrowth forest can be a ready supply of timber to the building market, but it is not as sustainable as plantation timber.

That iconic bark

Ironbark is named for its dark-coloured, fissured bark, which is not shed annually like many other species of Eucalyptus. Instead, the dead bark accumulates on the trees, becoming rough and hard as it is impregnated with kino (red gum) – a dark red tree sap exuded by the tree.

Fire resistant

This bark is also extremely resistant to fire, protecting the living tissue within the trunk. In some cases, if leaves and shoots are burnt off, the protective bark helps to insulate epicormic buds which allow the tree to reshoot.

Identifying different species

If you are trying to tell the difference between E. sideroxylon and E. tricarpa, there are a few ID tricks to keep in mind. Tricarpa often has lighter coloured grey bark, but the main point is to count the number of flower buds. There are always three on tricarpa (hence the name!), whereas sideroxylon will have either seven or nine buds on a stem.

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