Byron Flora and Fauna Study 1999 - Byron Shire Council

A GREENPRINT FOR A SUSTAINABLE FUTURE
Giant Ironwood (Choricarpia subargentea FAMILY MYRTACEAE)
Introduction. Giant Ironwood has a disjunct distribution, being found in NSW only on Mt Chincogan, and otherwise
from Boonah to Imbil in Queensland (Floyd 1989). Its rarity, and isolated occurrence on one of the Shire’s best known
landmarks, suggests a special significance for Giant Ironwood. No Recovery Plan has been prepared.
Conservation status. Giant Ironwood is listed on Schedule 1 (Endangered) of the TSC Act, 1995 and has a ROTAP code
of 3RC- (Briggs and Leigh 1996).
Habit. Tree with smooth brown bark, usually forming dense thickets on the margin of dry rainforest. Leaves are opposite,
glossy on the upper surface and silvery under (Harden 1991).
Flowers. Cream with numerous stamens (Harden 1991). Flowering period is April (Floyd 1989). No information about
its pollination is available.
Fruit. The fruit are clustered in dry globular heads (Harden 1991). The fruit ripens possibly in October (Floyd 1989).
Seeds are presumed to be wind-dispersed.
Habitat. In marginal regrowth of dry rainforest forming dense thickets with Backhousia sciadophora and occasional Guioa
semiglauca (Floyd 1989). Plants known on Mt Chincogan are clumps apparently grown from coppice shoots following
clearing, and surrounded by pasture.
Distribution. Found in NSW only on Mt Chincogan, and from Boonah to Imbil in Queensland (Floyd 1989).
Regeneration and horticulture. Giant Ironwood can be propagated from the tiny seed which should be lightly covered
with propagation mix, or cuttings (Jones 1986). Trees will grow in sun or shade, like an abundance of water, and are
hardy to moderate frosts. They are moderately fast-growing.
Economic and cultural significance. The tree is cut for timber (Jones1986), but is far too rare to be used in New South
Wales. Otherwise, no particular uses or significance are known beyond the aesthetic and ecological values of all native
rainforest trees.
Abundance and reservation. Confined in NSW and the Shire to Mt Chincogan. Giant Ironwood was first located on the
mid slope of the southern spur of the mountain in 1986. Further trees were recorded during the current surveys on the
southwest facing slope. Most plants are clumped, arising from coppice shoots. The clumps occur isolated in cleared
paddocks, or with remnant vegetation in gullies (southwest slope). 10-20 clumps of trees are known. No plants are
reserved in New South Wales. Giant Ironwood is also rare in Queensland, and the adequacy of its representation in
reserves is unknown (Briggs & Leigh 1996).
Threats and amelioration. In NSW the number of individuals is so low that chance events could threaten Giant Ironwood.
Natural expansion of the species is unlikely since the population is so small and isolated, and the regrowth in the immediate
vicinity is weed infested and exposed. The general area where it grows is grazed and exposed to the risk of fire from
flammable eucalypt plantations established downslope. To improve the conservation status of Giant Ironwood, the health
of the population and its regeneration potential should be enhanced by weed management, grazing exclusion, fire protection
and replanting of surrounding habitat. As Giant Ironwood grows in association with other threatened species
(Austromyrtus fragrantissima and Randia moorei) on the southwestern slope of Mt Chincogan, there are pressing reasons to
rehabilitate this area in particular. The dry rainforest which is apparently the preferred habitat of Giant Ironwood is rare
in the Shire.
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