From plants to vertebrates: Vegetation-derived ecological indicator values reveal habitat drivers of a micro-endemic alpine salamander

Understanding the ecological requirements of endangered species is key to developing effective conservation strategies. Vegetation-derived ecological indicator values (EIVs) are widely used to summarise environmental gradients shaping ecosystem properties, but their application to vertebrate ecology and especially to micro-endemic species, remains limited. Because plant communities integrate long-term abiotic conditions, values derived from vegetation composition may provide meaningful indicators of habitat characteristics, relevant to animals responding to the same gradients. Here, we evaluate whether EIVs explain spatial variation in abundance and detectability of the Golden Alpine salamander (Salamandra atra aurorae), a strictly terrestrial and micro-endemic amphibian of high conservation concern restricted to a small sector of the Italian Alps. We surveyed salamanders in 30 forest plots, each visited during eight sampling sessions, and analyzed the repeated count data using a Bayesian negative binomial N-mixture model to explicitly account for imperfect detection. Vascular plant composition was characterised using community-weighted mean of EIVs based on values provided by Landolt, which are vegetation-derived ecological indices reflecting species' realised environmental preferences along major abiotic gradients on Alpine region. Salamander abundance was strongly and positively associated with soil aeration EIV, while temperature EIV showed a consistent negative effect, indicating a preference for cool and well-structured forest-floor conditions. Humus EIV had a positive but weaker effect, suggesting an indirect influence mediated by forest-floor complexity. Overall, our results demonstrate that EIVs can effectively link forest ecosystem properties to animal abundance, supporting their use in conservation-oriented monitoring programs.