For more than a century, Australia’s Strzelecki Desert has slowly grown into two halves. On one side, a landscape with sand dunes reaching 10 meters (33 feet) high scattered amidst dense vegetation filled with woody shrubs. The other, a desert with short, fat dunes and little vegetation. Now, researchers believe these changes are driven by the world’s longest fence and the animals it's meant to keep out.
The “Dingo Fence” was originally built in the 1880s to deter the spread of rabbits before renovations at the turn of the 19th century aimed to keep the continent’s wild dogs on one side and away from livestock.
Researchers compared drone images of the landscape on either side of the 5,000-kilometer-long (3,100-mile) wire mesh fence with historical aerial photos between 1948 and 1999. Among other things, they found the side without dingoes had 60 more woody shrubs per hectare and dunes measuring as much as 66 centimeters (26 inches) taller. What’s responsible for the difference?
Publishing their findings in The Journal of the Royal Study Interface, scientists believe that the lack of dingoes has created a cascading effect. Without an apex predator like dingoes, foxes and cats have thrived in the last 100 years, killing small prey species like mice and rabbits. Vegetation on this side of the fence has flourished without rodents around to the eat plant seeds.
“Taken together, these findings provide evidence that the removal of apex predators may have effects that extend to the physical structure of the landscape, and that density of woody plants might be a key factor in controlling how those effects manifest,” wrote the authors.
The removal of the keystone dingo has had effects reaching right down to the “underlying physical structure of the landscape.” Shrub growth – or “shrub encroachment” – both holds sand and sediment down and causes wind to skim over their tops, causing dunes to grow taller and more stable.
As the authors note, removing large carnivores can have “profound effects” on ecosystems, as was the case when wolves were removed from Yellowstone National Park. Specifically, the researchers note how human infrastructure can induce these trophic cascades, indirectly leading to large-scale changes in landscapes.
A similar study conducted by the University of New South Wales this year found that the fence doesn’t only affect the abundance of other animals and plants but also reduces the quality of soil. The soil is healthier in areas where dingoes are present and feeding on kangaroos, reducing the number of marsupials grazing on vegetation.
The study concludes that future restoration is plausible with the reintroduction of dingoes.