Thread by @itsnotfairman

I loathe putting up another series of depressing fire maps - but after a chat with @jmorganecology, I made these showing the extensive fires that have occurred in the Victorian Alps since 2003, which have been added to this last few days. Another thread...

This map is centred on the Hotham and Bogong High Plains area and shows the extent of major bushfires between 1970 - 2000. Fires generally occured at the lower elevations, like the 1998 Caledonia fire in the south.

In 2003, there was the large Alpine fires which burned from Canberra to halfway through the Victorian Alps. These were the largest fires in Victoria since 1939.

The Great Divide fires of 2007 were the next major fire event. There was extensive areas of forest reburned at the junction of the two fires, which caused collapse of some Alpine ash forests (see: onlinelibrary.wiley.com/doi/abs/10.111…)

The 2009 fires, aka Black Saturday, also impacted some parts of the Alps and reburned some areas of 2003 burn.

In 2013, the Harrietville fires burned into forest already burned in 2003 and 2007, resulting in some areas of forest burned three times in ten years.

In 2019, a series of later season dry lightning storms in March (nine months ago), reburning areas of 2003, 2007 and 2013 burned forest.

Which brings us to January, 2020. More fire, creating more double and triple burned forest - there's probably few other ways to describe this than as a landscape of change.

I undertook part of my PhD research in the snow gum forests of these landscapes, specifically looking at the effects of the short-interval fires between 2003, 2007 and 2013. A summary is here:
pursuit.unimelb.edu.au/articles/recur…

Visually - this is the difference between an unburned and triple burned snow gum forest. Despite being resprouters, high fire frequency increases mortality, while seeming to favour grasses. My supervisors and I began to call these 'sub-alpine savannas'.

Alpine ash forests, similarly, are unlikely to persist after two high severity fires under 15-20 years - the age regenerating stems begin to produce seed. The former Alpine ash forest below is now likely to be a future acacia shrubland.

That all being said - there is still a lot to learn from this massive natural experiment happening up in the Victorian Alps - interactions between drought, fire, and different vegetation communities - and there are a heap of excellent researchers looking into this.