Hypervolume trait spaces reveal similarities but also functional differentiation across riparian, roadside and field margin habitats

•Aim: To characterize plant species pools and functional diversity of three common linear habitats—riparian corridors, roadsides and field margins—and to evaluate their potential roles in regional biodiversity conservation, particularly regarding invasive and threatened species.
•Location: Temperate landscapes in the United Kingdom, France and Spain.
•Methods: We compiled vegetation surveys and distinguished species common to multiple habitats and those restricted to a single habitat. We then compared taxonomic and functional diversity (as measured by hypervolumes) across habitats based on traits related to disturbance tolerance, ecological strategy and dispersal.
•Results: A quarter of the species pool was shared among the three habitats, and indicator‐species overlap was strongest between roadsides and field margins. Riparian corridors had the highest species richness, the greatest number of habitat specialists and the largest functional trait hypervolumes. Roadsides showed comparable richness but substantially lower functional diversity, whereas field margins supported the lowest richness. Although field margins had more disturbance‐adapted annuals, all habitats showed similar functional diversity in disturbance tolerance. In contrast, ecological strategies and resource requirements differed strongly, reflecting habitat‐specific filtering by hydrology, soil conditions and management regime. Invasive species were most frequent in riparian corridors and roadsides, tended to be large and suited to productive, disturbed environments, while threatened species were more habitat‐specific, generally small, sensitive to eutrophication and associated with frequently disturbed but nutrient‐poor sites.
•Main Conclusions: Riparian corridors emerge as hotspots of both taxonomic and functional diversity, but also as key invasion hotspots, whereas roadsides and field margins support narrower ecological strategies. The co‐occurrence of invasive and threatened species in disturbed sites within linear habitats, combined with their contrasting trait syndromes (height and nitrophily), highlights the need for coordinated management at a broader scale. Protecting vulnerable flora while limiting the spread of invasive species will require controlling nutrient inputs at the catchment scale.