Saturday, 24 March 2012

Megafauna Collapse led to Mega Vegetation Changes

On 23rd March 2012 Rachel Sullivan via ABC Science Online posted the article in this hyperlink (titled the same as what we've titled this blog post) highlighting the change that occurred in the vegetation in Australia post the extinction of most of our endemic mega-fauna: Reading Rachel's article inspired us to track down the original report in the Science journal. Here's a link to the Science Magazine website ( From there we found that the actual name of the full original report is titled "The Aftermath of Megafaunal Extinction: Ecosystem Transformation in Pleistocene Australia".

Given the significance of this report to what we believed to already be the case in terms of human impact on the Australian landscape we paid the USD 15.00 and downloaded the full report. Here's a copy of the unedited Extract from this report: "Giant vertebrates dominated many Pleistocene ecosystems. Many were herbivores, and their sudden extinction in prehistory could have had large ecological impacts. We used a high-resolution 130,000-year environmental record to help resolve the cause and reconstruct the ecological consequences of extinction of Australia’s megafauna. Our results suggest that human arrival rather than climate caused megafaunal extinction, which then triggered replacement of mixed rainforest by sclerophyll vegetation through a combination of direct effects on vegetation of relaxed herbivore pressure and increased fire in the landscape. This ecosystem shift was as large as any effect of climate change over the last glacial cycle, and indicates the magnitude of changes that may have followed megafaunal extinction elsewhere in the world."

The research and writings of well known Australian environmental scientist Tim Flannery bring to light that some 95 % of Australia's native megafauna is now extinct post human occupation and that most of these were herbivores (plant eaters). Page 119 of his book 'Future Eaters' has a table showing 48 extinct species including: 
  • Tree feller, marsupial rhino, large and small species of diprotodons
  • 5 species of wombats, giant rat kangaroo, and the marsupial lion
  • 7 species of giant short-faced kangaroos
  • 8 species of kangaroos
  • Dwarfed marsupials and monotremes
  • Various birds and reptiles
On Page 112 of the same book he lists some of the extinct predators as:
  • Gigantic goanna - Megalania - 200+ to 1000+ kg and measuring up to 7 metres long
  • Land crocodile - Quinkana - 200 kg+ and up to 3 metres long
  • 100 kg python - Wonambi - reaching 6 metres long with a 30 cm diameter
  • Several extinct crocodiles
It is basic human nature for survival and quality of life reasons that we rid or exclude critters in the environment that are a threat to our existence or comfort. Thus in our view blaming Aboriginal people for the extinction of the megafauna species is not appropriate. It's just the way of things. What the research does support is many of the principles espoused in the Holistic Management material developed by Alan Savory et. al. and the important role large herbivores play in restoring and maintaining land and soil health.

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