Ecological Risk Screening Summary - Chilean needle grass (Nassella neesiana) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.

Nassella neesiana is a grass native to parts of South America. N. neesiana has the ability to produce seeds through both asexual and sexual mechanisms. This species is used to support livestock as it can withstand heavy grazing. Little peer reviewed information is available on N. neesiana despite its spread and suspected impacts in some grassland environments. However, there is enough information to classify its History of Invasiveness as “high” and the available information is scientifically credible. N. neesiana lowers native biodiversity and may reduce the soil water content for other species when compared to native species. Climate matching indicated the contiguous United States has a high climate match. The areas of highest match were in the south and along the Pacific Coast. The certainty of assessment is medium due to most of the impact information coming from grey literature. The overall risk assessment category is High.