Widespread resilience of animal species, functional diversity, and predator-prey networks to an unprecedented gigafire

Climate change is altering fire regimes globally, leading to an increased
incidence of large and severe wildfires, including gigafires
(>100,000 ha), that homogenise landscapes. Despite this, our
understanding of how large, severe wildfires affect biodiversity at the
landscape scale remains limited. We investigated the impact of a gigafire
that occurred during the unprecedented 2019–20 Australian ‘Black Summer’
on terrestrial fauna. We selected 24 study landscapes, each 3.142 km2 in
size, that represented a gradient in the extent of high severity fire,
unburnt vegetation, and the diversity of fire severity classes
(‘pyrodiversity’). We used wildlife cameras to survey biodiversity across
each landscape, and quantified species activity, community and functional
diversity, and predator-prey network metrics. We used Bayesian mixed
effects models to assess the influence of fire-induced landscape
properties on these measures. Most native species showed resilience to the
2019–20 wildfires, displaying few relationships with fire-induced
properties of landscapes, including the extent of high severity fire,
unburnt vegetation, or pyrodiversity. Community and functional diversity,
and measures of predator-prey networks, were also largely unaffected by
fire-induced landscape properties, although landscapes with a greater
proportion of high-severity fire had higher abundance and richness of
introduced animal species. Synthesis and applications. Despite prevailing
narratives of widespread ecological destruction following the 2019-20
wildfires, our findings suggest widespread resilience, potentially
facilitated by evolutionary adaptations of animals to fire. Interventions
aimed at helping such species recover may not be necessary and could
instead focus on the subset of species that are vulnerable to severe fire.
While mixed-severity fires are often advocated to promote biodiversity
through pyrodiversity, our results suggest that such management efforts
might not be necessary in our study region. Given that severe fire favours
introduced animal species, invasive species management should focus on
large, severely burnt areas.