Alpine mires support distinct and vulnerable plant–pollinator networks compared to grasslands

Abstract Alpine mires are highly threatened habitats that support specialized biodiversity, yet their pollinator communities and plant–pollinator interactions remain poorly known. We compared plant and pollinator communities and their interaction networks in five alpine mires and five adjacent grasslands across the Western Italian Alps to assess differences in composition, network structure and robustness to species loss. Vegetation and pollinators, including hoverflies, bees, beetles and butterflies, were surveyed using standardized protocols. Mires supported lower plant and pollinator richness than grasslands, although 57.3% of mire plants and 47.2% of mire pollinators were recorded exclusively in this habitat. Plant and pollinator communities differed significantly between habitats, and macroplots with more similar plant communities also tended to support more similar pollinator communities. Both habitats hosted species of conservation concern, but mires were notable for several threatened hoverflies, including three Endangered Cheilosia species recorded exclusively there, whereas grasslands hosted two butterfly species listed in Annex IV of the Habitats Directive. Hoverflies showed similar richness and abundance in both habitats and dominated mire communities, whereas bees, beetles and butterflies were richer and more abundant in grasslands. Mire networks were smaller, contained fewer interactions and showed lower network-level specialization. Mire pollinator communities were less robust to the preferential loss of habitat-exclusive plants, while no habitat differences emerged under random plant-loss scenarios. These findings show that alpine mires and grasslands make complementary contributions to pollinator conservation, while small and fragmented mires support distinctive communities and interaction networks particularly vulnerable to vegetation change.