Butterfly assemblages as indicators of wildfire disturbance in recently burnt urban ecosystems

Urban ecosystems are exposed to increasing stressors, including habitat fragmentation and climate-driven disturbances e.g., wildfires. Identifying reliable biological indicators of both short- and long-term effects of these pressures is therefore crucial for urban biodiversity monitoring and management. Butterflies are widely recognized as sensitive bioindicators, yet their responses to wildfire in urban contexts is still poorly understood. In this work, we assessed the role of butterfly assemblages as indicators of wildfire disturbance in a recently burnt urban protected area within the metropolitan area of Rome (central Italy). We sampled butterflies across 18 sites representing different habitat types (grasslands, woodlands, and wetlands) and contrasting fire conditions, integrating species abundance data, functional traits and vegetation characteristics. We combined RLQ-fourth corner analyses, generalized linear mixed models, and indicator species analysis to disentangle trait-environment relationships and species-specific responses to both recent fire events and long-term fire frequency. Wildfire emerged as a key driver shaping butterfly community structure. Species with longer flight periods, higher mobility, and polyvoltine life cycles were favoured in burnt and frequently burned sites, whereas univoltine, specialized, and conservation-relevant species were negatively influenced. Indicator species analysis identified butterflies associated with both burnt and unburnt conditions, supporting the use of assemblage composition as a sensitive indicator of post-fire habitat condition. Therefore, integrating butterfly-based indicators into urban monitoring schemes can improve the assessment of disturbance impacts and inform adaptive fire management and conservation strategies in cities facing increasing wildfire risk.