Establishment of most grassland species was not more suppressed by invasive Sporobolus cryptandrus litter than by native grass litter

Abstract Sporobolus cryptandrus , a North American C4 grass, has recently invaded European sandy grasslands, particularly in Central Europe (Hungary), where it threatens native plant communities. As allelopathy has been documented for other Sporobolus species, we tested whether litter from S. cryptandru s has a different effect on the germination and seedling emergence of native grassland species compared to native grass litter. We examined nine native grassland species and S. cryptandrus under three treatments: no litter (control), native litter and S. cryptandru s litter. We hypothesized the followings: (i) Litter addition can hinder germination compared to no-litter control because litter imposes physicochemical barriers. (ii) Following the Novel Weapons Hypothesis, Sporobolus litter may exert a stronger negative effect on native species than native grass litter. (iii) Litter effects are likely species-specific due to interspecific differences in traits and sensitivity to microenvironmental changes. Litter presence did not have a consistent negative effect across species, Sporobolus litter negatively affected germination only in Bromus tectorum . For most other species, the effects of native and Sporobolus litter were highly similar, suggesting that Sporobolus litter did not introduce physicochemical characteristics sufficiently different from native litter to produce distinct effects on native species. However, the suppression of B. tectorum germination by Sporobolus litter may indicate potential allelopathic effects. These findings suggest species-specific litter effects and highlight that Sporobolus litter could offer novel insights for managing B. tectorum , a problematic invader in North America. Future research should explore the long-term effects of Sporobolus litter in guiding restoration actions and invasive species management.