60 billion invertebrates lost in mega-fires

A new study conducted by La Trobe University team led by Professor Heloise Gibb reveals the alarming loss of invertebrates in Australian temperate rainforests following the catastrophic bushfires in South Eastern Australia at end of 2019 and early 2020.

The research highlights the significant impact of high severity burns, with an estimated 60 billion invertebrates lost from forest floors in rainforests alone, compared to unburnt areas.

Highlighting the importance of invertebrates, Professor Gibb said insects are a vital food source for many species.

"Iconic birds like lyrebirds, as well as lizards and small mammals heavily rely on litter invertebrates for sustenance. Furthermore, invertebrates facilitate decomposition by breaking down litter, making it easier for microbes to decompose,” Professor Gibb said.

“If invertebrates are absent, this process will be hindered, potentially leading to longer-lasting combustible litter. Most invertebrate species in these systems are undescribed and have limited ranges, making it difficult to ascertain the extent of species loss due to fire.”

Rainforests in Australia account for only 1 per cent of all forests, so total loss of invertebrates from fires across all forests could be 100 times higher. Approximately 70 per cent of invertebrates in these ecosystems remain undescribed, and their distribution is largely unknown. Therefore, estimating the impact of fires at the species level is incredibly complex.

Professor Heloise Gibb said the research focused on temperate rainforests, which typically do not experience severe burns.

"Due to the exceptionally intense nature of recent fires, many of these rainforests were severely affected. Even a year after the fires, we observed distinct changes in habitat composition, with a significant decline in litter invertebrates in the severely burnt sites,” Professor Gibb said

“The findings indicate a loss of approximately 75 per cent of invertebrate abundance in rainforests affected by severe bushfires. This loss has far-reaching implications for the persistence of species in these areas and poses a significant threat to the functioning of ecosystems in the short term. Invertebrates play a crucial role in decomposition and nutrient cycling, and their absence can disrupt these essential processes.”

The study was conducted in East Gippsland and Southern New South Wales, encompassing rainforest areas in gullies along the coast. The research team surveyed 52 sites, comparing burnt and unburnt areas to assess the effects of the bushfires on invertebrate populations.

The survey used various methods, including traps to extract insects from the litter, enabling a comprehensive examination of the invertebrate community.

Study: Rainforest litter invertebrates decimated by high severity burns during Australia's gigafires

Media: Courtney Carthy – c.carthy-oneill@latrobe.edu.au +61 487 448 734

Image: Onychophora micro invertebrate, courtesy of Dr Nicholas Porch, Senior Lecturer in Environmental Earth Science
School of Life and Environmental Sciences, Deakin University