Spreading of recently introduced North American sand dropseed ( <i>Sporobolus cryptandrus</i> ) threatens European native dry grassland arthropods

Abstract Invasive plants can fundamentally impact ecosystems. As arthropods play prominent roles in ecosystem functioning via their food webs, understanding how plant invasion affects arthropod communities is essential. We studied the impact of the invasive grass ( Sporobolus cryptandrus ) on arthropods (ground beetles, orthopterans, spiders and true bugs) across three habitat types in Hungary: forest steppe, open sand grassland and meadow steppe. We compared the species composition of arthropod communities and the abundance of species of conservation interest between invaded and control plots. We also identified species indicative of either control or invaded plots. Additionally, we analysed the species richness and abundance of arthropod groups along a gradient of the invader density (low, medium, high and control). We found that species composition between invaded and control plots only differed for vegetation‐dwelling true bugs and orthopterans, with several species indicative of control plots. Their species richness and/or abundance decreased with increasing Sporobolus cover, varying among habitats. Interestingly, low Sporobolus cover increased the species richness and abundance of ground beetles and the abundance of vegetation‐dwelling, primarily web‐building spiders. However, the conservation value of true bug, grasshopper and ground beetle species was reduced in invaded sites compared to control sites. We conclude that low Sporobolus cover can temporarily increase species richness and abundance of some arthropod taxa, but this effect is likely short‐lived before Sporobolus rapidly gains dominance due to its fast spreading rate. Ultimately, Sporobolus invasion can reduce arthropod diversity, particularly affecting species of high conservation value.