Non-local genotypes of a resident grass species reduce invertebrate species richness

. 1. Effects of the genotypic identity of a plant can extend beyond the individual phenotype to the community. Because plant material is moved around at an increasing rate, introductions of non‐local plant genotypes that are difficult to distinguish from local ones are probably common. Even though such introductions can cause cryptic invasions, their effects on local communities remain largely unexplored. 2. Ammophila arenaria is transported and planted throughout the world for dune stabilisation. We used this grass to address the impact of the introduction of non‐local genotypes on the diversity of the local invertebrate community. We installed plants from the local population and five introduced populations from regions throughout the natural range in a common environment and identified all naturally colonising aboveground invertebrates. 3. The diversity of the entire invertebrate community, as well as that of herbivores, decreased with increasing geographical distance of the plants’ location of origin. Differences between plant populations in predator and detritivore diversity were less consistent with this pattern. Invertebrate species turnover was not related to genetic distance between populations. 4. Our study demonstrates that introduction of non‐local genotypes of a resident plant species can negatively affect the invertebrate community. This confirms the idea that caution should be exerted when selecting plant material for restoration or sand stabilisation purposes. Hitherto, explanations for the invasiveness of A. arenaria in other continents have been sought in its release from belowground pathogens. Our observation of lower shoot herbivore diversity on non‐local plants, however, may indicate a role for release from aboveground enemies.