Linking taxonomic diversity and ecological traits of geometrid moths and plants in coastal dunes: Insights from a Mediterranean LTER site

Geometrid moths are widely regarded as effective bioindicators due to their sensitivity to changes in local plant communities, their preference for woody habitats and their limited dispersal capabilities. We analyzed geometrid moths and vascular plants diversity patterns inside a monitoring site that is a node of the European Long-Term Ecosystem Research network (eLTER IT20), placed on the central Italy Adriatic dune coast including a well-preserved Mediterranean system. Moth and plant communities were sampled in two distinct dune zones (the shifting dunes and the fixed dunes) in three replicates. Geometrids were collected using traps equipped with UV LEDs. Vegetation surveys were conducted using plots with a stratified random design. For both geometrids and plants, we investigated differences between dune zones in species richness, species abundance distribution and trait characteristics. To assess variation and covariation within and between geometrid and plant traits, we applied a Two-block Partial Least Squares (2B-PLS) analysis. Finally, we assessed the congruence between geometrids and plants in species composition and abundance variations between zones. The two groups responded in similar ways to the dune zonation. Trait associations identified through 2B-PLS revealed a distinct ecological differentiation driven by dune zonation, with coordinated trait patterns between moths and plants. Significant cross-taxon correlations in community similarity were found when species abundance patterns were considered. Our findings emphasize the importance of preserving diverse dune zones as distinct habitats that support unique geometrid moth communities and their potential role as bioindicators of coastal habitat conservation status.