The invasive tropical tanner grass decreases diversity of the native aquatic macrophyte community at two scales in a subtropical tidal river

The tropical tanner grass, Urochloa arrecta, is one of the worst aquatic plant invaders in Brazilian freshwater ecosystems. This study aimed to compare beds macrophytes dominated and without U. arrecta Guaraguaçu River, a subtropical tidal river South Brazil, analyze effects that this invasive grass has on biodiversity native at two spatial scales. We compared macrophyte by without, considering species richness, composition, beta diversity scales variation: among-beds within-beds. expected would have lower biodiversity, thus promoting biotic homogenization. Our results confirmed our hypotheses, highlighting richness grass. Species composition differed among beds. In general, nestedness was more related variation composition. Beds had turnover higher within indicates prominent sign homogenization promoted highlights degree