In our final Science and Knowledge webinar for 2025, Professor Mike Letnic will share an overview of his research and findings on the topic of whether grazing by kangaroos disrupt the flow of food resources through brown food webs in arid environments.

The "brown food web" refers to the network of organisms that consume dead organic matter, which includes dead plants, animals, and waste. It is a decomposer-based food chain that contrasts with the "green food web," which is based on living plants and algae. Brown food webs are crucial for recycling nutrients, as they provide energy to a wide range of organisms like microbes, fungi, and scavengers that are a food source for other animals.

Irruption of herbivore populations due to the extirpation of predators has led to dramatic changes in ecosystem functioning worldwide. Herbivores compete with other species for their primary source of nutrition, plant biomass. Such competition is typically considered to occur between species in closely related clades and functional groups but could also occur with detritivores that consume senescent plant biomass. 

Professor Mike Letnic along with his colleagues have been investigating the idea that in ecosystems where kangaroos are not regulated by predators, their indirect impacts on dead vegetation increase with primary productivity and extend to termites that feed on senescent vegetation. They have been investigating the diets of small vertebrates and comparing dead vegetation cover and termite activity in kangaroo exclusion plots and associated grazed plots at Witchelina Nature Reserve and two other properties in arid Australia. 

Many desert vertebrates including birds, lizards and small mammals consume termites. Dead vegetation cover, termite activity and activity of termite consuming lizards tend to be greater in ungrazed than grazed plots. Their results suggest that grazing can disrupt the flow of energy to detritivores and decouple the relationship between termite activity and primary productivity. Disruption of brown food webs by herbivores could have far-reaching impacts on arid ecosystems because many organisms sit within brown food webs that are sustained by energy derived from the decomposition of senescent plant tissues.

In this webinar, Professor Mike Letnic will join host Dr Lucy Clive to share an overview of the research and findings, followed by a Q&A at the end of the presentation with an opportunity for you to submit your questions.

This webinar will be recorded and shared in the news section of our website in the days following the live broadcast.

Register here.