Fire and the forest

Transcript

Fire’s been part of the Australian ecosystem for probably about 30 million years.  It’s been a long time and it’s gone hand in hand in the development of our unique fauna and flora. So our eucalypts, our acacia flora for example, basically started to spread across the continent when fire became more common.

The dry forests of Victoria are largely in foothill sort of country, so the foothills are areas where we get reasonably high rainfalls which means their fairly rich in fauna and flora in those areas. But they also get subjected to seasonal drought conditions and it is in those dry conditions that we tend to get more fires occurring. And one of those things that probably often missed is that fire creates an opportunity for regeneration of particularly the plant species but it needs to be fire with a certain pattern and distribution across the landscape.

Some fires, they’re so intense and so large, that they create a long term structural change to the environment. So large intense fires can be a part of the process but they might be one in a 100 year, one in 200 year type event, where as if they start to occur every 20 years we totally change the structure and even the species composition.

What we’ve been seeing in recent times we’re seeing an increase in the frequency of drought, but we’re also seeing increased moisture in summer but that moisture not resulting in a lot of rain and a lot of run off and a lot of soil wetting, it’s actually increasing the amount of lightening activity we get, and lightening is a natural source of ignition of bushfires. So that’s really quite important because a lot of lightening actually occurs in quite remote areas and whilst lightening fires might only start about a third of the fires they actually burn about three quarters of the area that actually burnt by wildfires.

So when we’re talking about climate change it’s not a gradual process, we actual see a very rapid transition from one state to another, so we’re starting to see more fire, more fire in remote areas, and those fires are tending to be larger because of the drought conditions we’re subjected to.

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About this Video

Kevin Tolhurst, Melbourne University, describes how Victoria’s forests have evolved with fire for millions of years.
Length: 02:23