Dingo effects on the ecosystem visible from space

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The impact of removing dingoes from the landscape on the environment is visible from space, a new UNSW study in Sydney shows.

The study, recently published in Landscape ecology, combines 32-year-old satellite imagery with field research on both sides of the Dingo fence in the Strzelecki desert.

The researchers found that the vegetation inside the fence – that is, the area without dingoes – had poorer long-term growth than the vegetation in the areas with dingoes.

“Dingoes indirectly affect vegetation by controlling the number of kangaroos and small mammals,” says Professor Mike Letnic, a senior study author and researcher at the UNSW Center for Ecosystem Science.

“Once the dingoes are removed, the number of kangaroos increases, which can lead to overgrazing. This has further effects on the entire ecosystem.”

The Dingo fence, which stretches to parts of Queensland, NSW and South Australia, was erected in the 1880s to keep the dingoes away from livestock. With a length of 5,600 kilometers, it is one of the longest buildings in the world.

So far, most ding research has been site-based or conducted using drone images. But NASA’s Landsat program of the United States Geological Survey – which has been capturing continuous images of the area since 1988 – has made it possible to analyze the landscape.

“The differences in grazing pressure on each side of the fence were so pronounced that they could be seen from space,” says prof. Letnic.

Satellite images were processed and analyzed by Dr. Adrian Fisher, a remote measurement specialist at UNSW Science and lead author of the study. He says that the response of vegetation to rain is one of the key differences between areas with and without dingoes.

“Vegetation grows only after rain, which is sporadic in the desert,” says Dr. Fisher.

“Although the rains caused vegetation to grow on both sides of the fence, we found that vegetation in dinghy-free areas did not grow as much – nor did it cover as much land – as areas outside the fence.”

Domino effect

Apex predators play an important role in maintaining ecosystem biodiversity.

Removal from the area can cause a domino effect for the rest of the ecosystem – a process called the trophic cascade.

For example, an increase in the kangaroo population can lead to overgrazing, which in turn reduces vegetation and impairs soil quality. Less vegetation can interfere with the survival of smaller animals, such as critically endangered lowland strays.

Vegetation changes caused by dingo removal have also been shown to alter the shaping of the desert landscape by altering wind flow and sand movement.

“Removing the tops of predators can have far-reaching effects on ecosystems that manifest over very large areas,” says Prof. Letnic. “These effects have often gone unnoticed because large predators have long since been removed from many places.

“The Australian dingo fence – which represents a sharp division between the dingo and non-dingo areas – is a rare opportunity to spot the indirect role of the top predator.”

A rugged, dry landscape

Satellite images traditionally only look at the vegetation of photosynthesis – that is, plants, trees and grass that are visibly green.

But the researchers used the model to factorize green vegetation, such as shrubs, dry grass, twigs, branches and leaf litter.

“Vegetation that does not perform photosynthesis has a different spectrum of reflection than vegetation of photosynthesis,” says Dr. Fisher.

“Using a satellite image and a calibrated scientific model, we were able to estimate the non-green vegetation cover – which is especially important when studying a desert landscape.” The model was developed by the Joint Remote Sensing Research Program, a collaborative group that includes UNSW.

Although there are other factors that contribute to differences in vegetation – for example, different rain patterns and land use – satellite imagery and site analysis have shown that dingoes play a central role.

“There were clear differences in the landscape on both sides of the dingo fence,” says Dr. Fisher. “Dingoes may not be the whole explanation, but it’s a key part of it.”

Exploiting satellite intelligence

Satellite imaging technology is a powerful tool for assessing the large role of not only dingoes, but also all kinds of changes in the environment.

In 2019, researchers from UNSW Engineering used powerful satellite radar imaging technology to map severe floods in near real time – intelligence that could help emergency services make tactical decisions during extreme weather events.

Dr. Fisher hopes that the next use of Landsat’s paintings – which is available for free download – will study how different amounts of vegetation can affect the frequency of shrubs.

“Our research is an example of how satellite technology can be used in extensive environmental research,” says Dr. Fisher.

“With more than three decades of data, this technology has opened up so many research opportunities.”

A study of the Dingo fence shows that the extinction of the dingo leads to poorer soil

More information:
Adrian G. Fisher et al., Remote sensing of trophic cascades: multi-time land images reveal vegetation changes caused by the removal of a peak predator, Landscape ecology (2021). DOI: 10.1007 / s10980-021-01206-w

Provided by the University of New South Wales

Citation: Dingo effects on the ecosystem visible from space (2021, 23 February) retrieved 23 February 2021 from https://phys.org/news/2021-02-dingo-effects-ecosystem-visible-space.html

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