It's Sad, But Burgan Is Bad!

(A note from Dianne Simmons)

Danger from Elevated Fuels

Shrubby vegetation (or elevated fuels) result in extreme fire behaviour even on days of moderate summer weather. Over the last few years, Burgan (Kunzea ericoides) seems to have become more common in the Bend of Islands.

I am concerned that in many areas with dense Burgan, there is an increasing fire risk, both to individual houses, and to vehicles (such as fire trucks) on the roads. Areas around Catani Boulevard, Ironbark, Gongflers and even Skyline Road will pose a considerable risk because of extreme fire behaviour. If your driveway or house is close to Burgan, our advice is get rid of it !!

How far is far enough ?

That is a hard question, but at least we can give some upper and lower limits to the clearance distances required. No one should have much shrubby vegetation within 30m of a house (don't worry about the trees). Information from the Hobart fires suggests that no defended houses burned down in Hobart that were more than 100m from the forest edge.

So it seems that somewhere between 30 and 100m clearance is required for house survival. If you want to survive a bushfire, then around 50m or so would seem to me to be a bare minimum, given the fire intensities likely to be generated from the dense Burgan elevated fuels. Even green Burgan burns readily.

If you don't want to clear this sort of distance, you need to be aware that you are exposing your house to considerable risk, and it may not be safe to use your house as a refuge during a fire. This is a hard decision, but I think we need to come to grips with the extreme hazard that Burgan poses in many parts of our area.

How do we get rid of it ?

The answer is simple...with great difficulty ! Once-off clearance is likely to result in rapid recolonization, and long term removal is going to be a difficult task.

It seems that other structurally similar species like Tea-Tree (Leptospermum spp) have a very different ecology to Burgan. For example, Tea-Tree is a good colonizer of bare ground (like Burgan), and then over a few decades reaches the end of its life-span, and dies back, often to be replaced with other species, and even perhaps an opening up of the vegetation. However, it seems that Burgan does not respond in this way. Once you have it, it just gets thicker. It can invade open areas as a colonizer, and also regenerate under a thick canopy of existing plants. It may be extremely difficult to replace Burgan with other more desirable species in the long run.

The best advice is to get rid of single plants to ensure that Burgan does not manage to expand to dominate and exclude other species.

References

Burrell, J.P. (1981) Invasion of coastal heaths of Victoria by Leptospermum laevigatum (J.Gaertn.) F.Muell. Australian Journal of Botany 29, 747-64.

Singer, R.J. and Burgman, M.A. (1999) The regeneration ecology of Kunzea ericoides (A.Rich.) J.Thompson at Coranderrk Reserve, Healesville. Australian Journal of Ecology 24,18-24.

Kirschbaum, S.B. and Williams, D.G. (1991) Colonization of pasture by Kunzea ericoides in the Tidbinbilla Valley, ACT, Australia. Australian Journal of Ecology 16, 79-90.

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