Slow, cool burns will reduce fuel loads

Maurie Killeen
Maurie Killeen


I AM writing in response to letters to the editor regarding bushfire prevention.

Discussion of climate change needs to be separate to the discussions of bushfires, and the mention of "doubts over current prescribed burns policy" is worthy of further comment.

First, we have to stop burning large areas, and classing them as eco and fuel reduction burns - which they are not.

Large, hot fires - whether they are wildfires or "managed" fuel reduction fires - promote accelerated growth for more frequent fires.

Our forests have been changed by management policy of 30-plus years of fire treatment, with an occurrence of mainly extreme and wild bushfire as well as large hot prescribed burns.

There has been a small number of moderate wildfire and cool prescribed burns, and large areas of forest with no fire treatment for many years.

Many of the hot fires developed into crown fires, letting the direct sunlight in to strike the seeds and a new forest of eucalypts would shoot up and grow.

Then the canopy would finally restore and grow over, blocking the direct sunlight leaving this mass of new forest with nowhere to go.

The new forest becomes stunted and bushy, forming a third layer of high loads of leaf and twig fuel.

The forest then has high concentration of dry leaf fuel on the forest floor from the previous burnt crown, and now the middle layer up to four times the fuel load of the original forest.

This third layer makes a violent stepping stone to activate a crown fire from even a docile fire on a mild day, resulting in most bushfires and prescribed burns in the past 30 years ending up as part or all crown fires.

The indigenous-managed forest of days gone by had a closed canopy and low vegetation bushes of one metre or less on the forest floor, forming two levels of fuel, not three levels.

Diaries of the early European explorers all speak of a clean forest floor and "park-like" when they travelled through the forests, and commenting the indigenous didn't burn the rivers and swamps.

The policy needs to be changed to introduce a modern indigenous management fire regime.

There is a need to have more one vehicle width or rake hoe tracks kept open to many small patches to burn out within a day.

This way a fuel reduction burn is not given a chance to build up to a hot fire.

Small cool burns produce very little smoke.

The prescription for these small burns would need to be revised to have clearance to be lit whenever the hour suits.

After a concerted effort for say, 10 years, a mosaic of lots of cool burned small patches is created all at different times, resulting in flora and fauna having a huge chance to survive.

Then we would be ready to operate as the indigenous burns were managed and some of those lightning strikes could be left to burn out. Also the thrill of a statement by arsonists would diminish.

In some areas after a few cool burns are carried out it should get to the stage the vegetation will slow its growth considerably, and very little or any burning would not be needed for a long time.

Regarding the alpine forests, there was a view that the indigenous managers didn't burn them, but burnt the lower forest which was a buffer to protect the alpine forest.