Trophic cascades in NSW North Coast forests

Trophic cascades in NSW North Coast forests

Honours project by Charlotte Mills and supervised by Mike Letnic.

The worldwide loss of predators has highlighted their important role as trophic regulators in ecosystems. Predators can indirectly impact upon lower levels in a food web through regulation of prey species and therefore alter plant communities in a trophic cascade. Terrestrial apex predator mediated trophic cascades are often only detected once the landscape has been visibly altered by predator removal.

The dingo initiates a trophic cascade with macropods and vegetation in arid Australia. Although dingoes are common in many environments in Australia, the indirect impacts of their activity within the forest environment have largely remained unstudied.

In this project we investigated evidence for a trophic cascade mediated by dingoes in the forests of the Great Lakes area of New South Wales. Differences in dingo control at three sites in the area generate a gradeint of dingo control. I used camera trap surveys and dung surveys to index dingo and macropod activity across this gradient, and compared vegetation structure and composition between paired plot exclosures situated in recently burnt areas. I expected that macropod activity should be greatest at sites with sustained dingo control and lowest at sites with no dingo control. Conversely, I expected that the difference in vegetation structure and composition between grazed and ungrazed plots should be greatest at the sites with sustained dingo control and least at sites with no dingo control. 

My results showed that dingo activity was lowest at the sustained baiting site and greatest at the unbaited site. Despite evidence of an impact of macropod activity on vegetation structure and a strong negative correlation between dingo activity and macropod activity, the effect of herbivores on vegetation did not scale with dingo control. 

Research Program: 
Predators
Research Themes: 
Terrestrial Ecosystems
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