Spartina patens as a weed in Galician saltmarshes (NW Iberian Peninsula)

Spartina patens (Gramineae) is an American coastal grass which grows in a w ide range of coastal habitats in its native area. After it was discovered i n some Galician wetlands two years ago, we undertook a regional survey whos e preliminary results reveal that this grass is actually a rather common sp ecies in Southwestern Galicia, being present in several coastal habitats al so. Nevertheless, it is in saltmarshes where it seems to compete more succe ssfully, invading rush communities that have been traditionally harvested f or cattle bedding. In many estuaries, it tends to form dense monospecific s tands and could become a serious threat to high marsh plant diversity. In o rder to evaluate the impact of S. patens as an invasive weed in saltmarshes , we have performed a transect study, which seems to indicate that S. paten s establishes preferentially in the upper marsh (but reaching higher covera ges in the uppermost part of its altitudinal rank), where it has a signific ant negative effect on species diversity as well as on total cover of other species.