This study analyses how vegetation cover and structure have influenced the functional diversity of terrestrial snails in the Serra de Collserola over the last two decades. Using LiDAR data and vegetation indices (NDVI and EVI), combined with functional trait-based metrics and diversity indices of land snail communities from 2003 and 2023, we assessed the relationship between environmental changes and snail functional diversity. Generalized linear models (GLMs) and redundancy analysis (RDA) were used to evaluate these patterns. Results indicate a temporal trend toward denser and more homogeneous vegetation due to afforestation and agricultural abandonment. This shift has favoured functional traits associated with humid, closed habitats, while reducing traits typical of species from open environments, potentially leading to a loss of functional redundancy and ecological resilience. Although the overall relationship between vegetation complexity and functional diversity was partially confirmed, the effect varied depending on the functional index or trait considered. This research represents a novel contribution to the field of malacology, integrating remote sensing tools and functional ecology. The findings highlight the importance of considering functional diversity in conservation planning and suggest that vegetation heterogeneity plays a key role in shaping snail communities. Continued investigation into these dynamics will help develop better-informed strategies for biodiversity management in Mediterranean ecosystems

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