Spartina patens (Aiton) Muhl.

we can conclude from this work that Spartina patens is a new alien species for the Galician flora, although probably introduced a long time ago, being specially frequent – and locally very abundant – on the southwestern Galician coasts. Its preferred habitat is the upper limit of saltmarshes, becoming invasive and with a noxious effect on plant diversity of native communities when it forms very dense stands (often pure patches with 100% cover of this grass). Keeping in mind cases of S. patens introductions elsewhere (Frenkel, 1987; Frenkel & Boss, 1988; Mumford et al., 1991; Daehler & Strong, 1996), we should consider it as a threat to the biological diversity of Galician saltmarshes and take action towards eradicating the grass or at least curbing its expansion. (SanLeón et al., 1999)

We explored consequences of the invasion of non-indigenous Spartina patens to the composition of soil organic matter (SOM) and to detritivore and herbivore diets in the upper salt marsh within Corrubedo National Park, northwest Spain. We tested for the incorporation of S. patens carbon (C) into SOM and by detritivores and herbivores using stable isotope analysis, focusing primarily on detritivorous enchytraeid oligochaetes and herbivorous insects. .... The population and dietary response of enchytraeids to S. patens suggests that S. patens invasion could indirectly influence soil processes and pathways mediated by detritivore activity (e.g., soil respiration rates, nutrient retention and transformation, energy flow). The loss of food resources to insect herbivores alters local food webs. ​However, insect herbivores may move and feed on native plants elsewhere. As a result, insect populations may be less immediately impacted than soil detritivore populations by S. patens. Our study suggests that the influences of S. patens invasion extend beyond the more obvious changes in native plant abundance, to include differing responses in the cycling of organic matter between detritivore and insect herbivore food web pathways.