Dingoes help outback balance
Satellite imagery shows the effect of removing dingoes from the landscape.
The study pairs 32 years’ worth of satellite imagery with site-based field research on both sides of the Dingo Fence in the Strzelecki Desert.
The researchers found that vegetation inside the fence – that is, areas without dingoes – had poorer long-term growth than vegetation in areas with dingoes.
“Dingoes indirectly affect vegetation by controlling numbers of kangaroos and small mammals,” says Professor Mike Letnic, senior author of the study and researcher at UNSW’s Centre for Ecosystem Science.
“When dingoes are removed, kangaroo numbers increase, which can lead to overgrazing. This has follow-on effects to the entire ecosystem.”
The Dingo Fence, which spans across parts of Queensland, NSW and South Australia, was erected in the 1880s to keep dingoes away from livestock. At 5,600 kilometres long, it is one of the longest structures in the world.
Up until now, most dingo research has been site-based or conducted using drone imagery. But NASA and United States Geological Survey’s Landsat program – which has been taking continuous images of the area since 1988 – has made landscape-wide analysis possible.
“The differences in grazing pressure on each side of the fence were so pronounced they could be seen from space,” says Professor Letnic.
The satellite images were processed and analysed by Dr Adrian Fisher, a remote sensing specialist at UNSW Science and lead author of the study. He says the vegetation’s response to rainfall is one of the key differences between areas with, and without, dingoes.
“Vegetation only grows after rainfall, which is sporadic in the desert,” says Dr Fisher.
“While rainfall caused vegetation to grow on both sides of the fence, we found that vegetation in areas without dingoes didn’t grow as much – or cover as much land – as areas outside the fence.”
Apex predators play an important role in maintaining the biodiversity of an ecosystem.
Removing them from an area can trigger a domino effect for the rest of the ecosystem – a process called trophic cascade.
For example, an increase in kangaroo populations can lead to overgrazing, which in turn reduces vegetation and damages the quality of the soil. Less vegetation can hinder the survival of smaller animals, like the critically endangered Plains Wanderer.
Changes to vegetation triggered by the removal of dingoes have also been shown to reshape the desert landscape by altering wind flow and sand movement.
“The removal of apex predators can have far-reaching effects on ecosystems that manifest across very large areas,” says Professor Letnic.
“These effects have often gone unnoticed because large predators were removed from many places a long time ago.
“The Australian dingo fence – which is a sharp divide between dingo and non-dingo areas – is a rare opportunity to observe the indirect role of an apex predator.”