Asynchronous postfire recovery dynamics between epilithic lichens and vascular plants in Mediterranean ecosystems

Wildfire has been a recurring natural disturbance within the Mediterranean Basin, leading to the evolution of adaptive traits in some plant species that enable them to survive or have high resilience fires. This study investigates the short-term resilience of vascular plants and epilithic lichens in Sardinia, Italy, following a Mediterranean megafire in 2021, focusing on taxonomic and functional diversity. Using a stratified random sampling method, 59 plots (40 burnt and 19 control) were analysed in two years post-fire, examining species richness and functional traits in vascular plant and lichen communities. Results indicate a significant asynchrony in resilience: lichen diversity and species abundance were severely compromised, whereas vascular plants showed a high degree of taxonomic and functional recovery. Lichen α-diversity was positively correlated with rockiness and negatively correlated with fire intensity, indicating that substrate availability is a critical resilience factor. Although vascular plants have recovered well, the lag in lichen resilience highlights a functional imbalance in the ecosystem. Although some lichen species may exhibit fire adaptation, our research demonstrates that the short-term resilience of the epilithic lichen communities we examined was markedly low. The study supports the need for cross-taxon approaches to ecosystem restoration and highlights the importance of considering a variety of taxonomic groups when assessing post-fire resilience.