Post-fire habitat relationships for birds differ among ecosystems

Abstract

Knowledge of how factors such as climate, plant regeneration traits and fire characteristics influence the rate and pattern of post-fire habitat change is crucial for strategic fire management and biodiversity conservation in fire-affected areas. Yet knowledge of when and where these factors are in play, and how species-habitat relationships differ among ecosystems, is limited. We modelled the responses of 43 bird species to habitat attributes, sampled along a 79-year post-fire chronosequence in three eucalypt-dominated ecosystems characterised by tree species with either basal or epicormic regeneration traits. In each ecosystem, birds responded to habitat attributes known to be related to time since fire, but the most important attributes differed among ecosystems. In foothill forests and heathy woodlands, in which eucalypts resprout epicormically, species responded most strongly to midstorey attributes and not the tree layer. In mallee woodlands, in which high-severity fires are ‘stand-replacing’ and eucalypts resprout basally, species responded most strongly to canopy tree size. Regeneration traits profoundly influence how rapidly the tree layer, important habitat for birds, is restored – within several years with epicormic resprouting, or over decades with basal resprouting. Notably, most species (~60%) that occurred in more than one of the ecosystems studied responded to different habitat attributes in each. Species' relationships with post-fire habitat are not necessarily transferable between ecosystems. In ecosystems that experience stand-replacement, time since fire is a useful habitat surrogate; but in ecosystems where trees remain standing after disturbance, time since fire is a more useful surrogate for some species (mid-storey-foragers) than others (canopy-foragers).