Spartina patensas a weed in Galician saltmarshes (NW Iberian Peninsula)
Spartina patens (Gramineae) is an American coastal grass which grows in a wide range of coastal habitats in its native area. After it was discovered in some Galician wetlands two years ago, we undertook a regional survey whose preliminary results reveal that this grass is actually a rather common species in Southwestern Galicia, being present in several coastal habitats also. Nevertheless, it is in saltmarshes where it seems to compete more successfully, invading rush communities that have been traditionally harvested for cattle bedding. In many estuaries, it tends to form dense monospecific stands and could become a serious threat to high marsh plant diversity. In order 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. patens establishes preferentially in the upper marsh (but reaching higher coverages in the uppermost part of its altitudinal rank), where it has a significant negative effect on species diversity as well as on total cover of other species.