Dead river red gums line a dry creek west of Mildura, Australia. Photo: Gillis Horner

By Dale Nimmo, David Lindenmayer, John Woinarski, Ralph Mac Nally, Shaun Cunningham
2 May 2016

(The Conversation) – Media reports around the world have brought the mass coral bleaching of Australia’s Great Barrier Reef into people’s offices and homes.

With 93% of individual reefs showing bleaching, the devastation among researchers, celebrities and the public is palpable.

Unfortunately, mass coral bleaching is just one example of a far broader problem. Although it represents a rapid and extensive example of ecosystem degradation, coral bleaching is not surprising: it is consistent with many changes that are occurring now across Australia’s natural environments.

The degradation and death of forests

Forest dieback is increasingly common across Australia from the high country and the floodplains to the savannahs.

Our iconic trees – including the world’s tallest flowering plant, the Mountain Ash, and the most widely distributed eucalypt, the River Red Gum – are among the hardest hit.

A stark example is the floodplain forests of the Murray-Darling Basin. Reduced rainfall and water extraction for human needs have deprived River Red Gums of the flooding integral to their existence. The consequence is that 79% of forests on the Murray River have dieback. Tree graveyards are a common sight.

Recent extreme weather combined with recurring wildfire and intensified logging has increased mortality rates of large, old Mountain Ash trees by an order of magnitude. This has created a crisis for the animals that depend on them, including the critically endangered Leadbeater’s Possum.

The plight of these forests foreshadows the fate of others (such as Western Australia’s Jarrah forests) under a drying climate.

The decline of south-eastern Australia’s frogs

Australia’s record-breaking Millennium Drought hit frog communities very hard. They have not recovered since.

It was hoped that the heavy rainfalls from late 2010 to early 2012 (the “Big Wet”) would help the frogs “bounce back”, given their capacity to lay large numbers of eggs under suitable conditions.

Modest improvements at the time of the Big Wet were undone with a return to dry conditions. These pushed the frogs back to the dire levels seen during the peak of the drought.

Species whose calls will be familiar to many Australians — the “crick-crick” of the common froglet, the “plonk-bonk” of the pobblebonk — saw very little post-drought recovery. [more]

Great Barrier Reef bleaching is just one symptom of ecosystem collapse across Australia



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