Wattles and Bushfires
Alan Gray
I was interested in the little note regarding the flammability (or otherwise) of acacias in Issue 99 of the Acacia Study Group newsletter. I just thought I'd pass on the following as an addition to the story. We live on a 7 ha bush block about 30 km south of Hobart, in a pretty fire-prone locality and the risk of wildfires is always uppermost in our minds during summer, particularly as we lost our first home in the '67 disaster!
I was a member of the local volunteer fire brigade for some years and have seen quite a few bad fires during that time and as a botanist I was interested and careful to note and record the flammability characteristics of the bush in which we were working. A number of species of plants are clearly very hazardous, the top of the list being Eucalyptus (Myrtaceae in general!). But some seemed to be useful fire "stoppers" and thus suitable options for planting or retention (at a safe perimeter) nearer residences etc.
Some of the naturally occurring Tasmanian wattles fall well within this category, some do not, e.g. A.verniciflua. However, whereas I do not doubt that A.mearnsii is a relatively low to non-flammable species, A.dealbata (silver wattle) is also a safe option, but that is not the only reason I planted a band (copse) of this species about 30 m away and to the north-west of our house. During one rather nasty wildfire, some years ago, I observed a group of silver wattles right in the path of the fire which was being fanned by a stiff northerly wind. Embers and flaming bark 'arrows' were flying along in front of the fire but were being effectively stopped or impeded by the fairly dense wattle canopies, and falling to the ground. The crowns were not igniting but were acting as efficient ember stoppers!
"Touch wood" my silver wattle barrier has not yet been put to the test but they remain a delightful silvery grove of tall wattles that are a sheer delight in spring, and, I hope, a barrier of some effect should "that day" blow up.
Of the rather paltry list of wattles with which Tasmania has been blessed, I would also recommend A.melanoxylon, A.mucronata (sens. lat.) and A.terminalis, as well as A.mearnsii for their fire retardant properties, among other reasons.
From the newsletter of ASGAP's Acacia Study Group, March 2008.
Australian Plants online - 2008
Association of Societies for Growing Australian Plants
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