Fighting the flames: site-specific effects determine species richness of Australian frogs after fire

ContextFire has played an integral role in regulating patterns of biodiversity for millions of years. However, anthropogenic disturbance and climate change has altered fire activity - driving increases in both fire severity and scale. The effect fire now has on the persistence of biodiversity is poorly known, especially for frogs. Studies examining frog responses to fire usually have small sample sizes, focus upon small geographic areas and are based on low-severity fires, which can mean results are not applicable to high-severity fires, such as those expected under future climate change.AimsOur aims were to examine (1) persistence of frog species, measured by species richness, up to 18 months post-fire, and (2) the effects of varying fire severity on frog species richness and recovery, where we expected higher fire severity to lead to lower species richness after fire.MethodsUsing large-scale citizen science data from the Australian Museum's FrogID project, coupled with remotely sensed fire data, we present a spatially and taxonomically broad analysis examining post-fire recovery responses for Australian frog species after the 2019/2020 'Black Summer' bushfires.Key resultsWe reveal no overall decrease in the species richness of Australian frogs both in the short- and long-term post-fire. Furthermore, species richness did not decline with increasing fire severity. Instead, species richness and its response to fire was highly site-specific.ConclusionsWe provide evidence that widespread and common Australian frog species have persisted post-fire in most sites and concluded that this is potentially due to their ability to shelter from fire adequately and/or La Nina-driven high rainfall offering conditions conducive to breeding activity and persistence.ImplicationsWe show how citizen science provides critical data for conservation, especially in response to unprecedented disturbance events, such as the 2019/2020 megafires. Our research also highlights the need for ongoing and targeted scientific monitoring, especially for less common or threatened species. Through citizen-science and remotely sensed data, we found no overall decrease in species richness of frogs after the 2019/2020 megafires, or with increased fire severity. Our results instead provide evidence that species richness and its response to fire is site-specific, and we explore possible explanations for this, while emphasising the need to monitor threatened and less-common frog species. Photograph by Jodi Rowley.