Effects of a megafire vary with fire severity and forest type: The impact of Australia's ‘Black Summer’ fires on the superb lyrebird (Menura novaehollandiae), an iconic forest species

Abstract

Megafires, predicted to become more frequent with a changing climate, pose a global challenge for conservation. Initial assessments of the 2019/20 megafires of Australia's ‘Black Summer’ highlighted widespread, severe impacts for many species. Post-fire empirical investigations are critical to evaluate the distribution and conservation status of species. We investigated the impacts of megafire on the southern superb lyrebird (Menura novaehollandiae victoriae), a functionally important ecosystem engineer in forest ecosystems. We quantified the extent of lyrebird habitat burned at differing levels of severity, and how this varied among forest types. One-year post-fire, we carried out field surveys at 226 sites, stratified by forest type and fire severity, to assess the impact on lyrebirds. In total, 41.5 % (~2.1 million ha) of habitat was burned at differing levels of severity. Habitats of higher predicted quality were disproportionately affected. At one-year post-fire, lyrebirds were strongly affected by fire severity: their occurrence, as indicated by foraging activity, was greatly reduced in forests burned at high and low severity, but patchily burned forest differed little from unburned forest. Notably, foraging was almost completely absent from all sites that experienced high severity fire, except in rainforest. Rainforests (<1 % of distribution) have the greatest post-fire value for lyrebirds; they serve as local refuges for recolonization and are a priority for restoration efforts. Importantly, impacts of megafires are not uniform but vary greatly in relation to fire severity and forest type. Such knowledge is essential for long-term conservation of species of concern, including the identification and protection of refuges.