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Spartina alterniflora is a smooth cordgrass that is commonly found in marshes. Its two forms (tall and short) naturally exist along the Atlantic coast of North and South America (Adam 1990; Bertness 1985). The grass has stiff stems with long and narrow leaves. The flowering portion of the plant is spike-like and can be up to 30 cm long (Wan 2009). It inhabits salt marsh habitats which are known for their anoxic, nutrient limited, and high salinity conditions (Adam 1993). Spartina alterniflora competes with Spartina patens, Juncus gerardi, and Distichlis spicata and the delineation between species appears to be due to both physical stress and nutrient limitation (Levine 1998). S. alterniflora ameliorates the environment and allows for other species to grow and flourish, such as the algae Ascophyllum nodosum and Haleobia australis (hydroboid snails) (Gerard 1999; Canepuccia 2007). In addition to facilitating the growth of organisms indirectly as an ecosystem engineer, S. alterniflora also plays a direct role as a food source for some organisms, although Spartina usually does not experience much herbivory. One consumer of S. alterniflora is the periwinkle snail, Littoraria irrorata, which forms wounds on the leaves and facilitates fungal growth, which is then harvested (Silliman & Newell 2003). Planthoppers, Prokelsia marginata and Prokelsia dolus specialize on Spartina and are found to coexist on Spartina throughout the north east of the United States (Denno et. al. 2000). Grasshoppers are also found to graze on S. alterniflora, with species varying according to lattitude (Pennings and Silliman 2005). Additionally, wild horses appear to prefer grazing on S. alternifora over D. spicata (Furbish 1994).
S. alterniflora provides numerous ecosystem services. These include protection from storm surges, capturing sediment, and filtering pollutants (Maricle 2002; Wan 2009). It is for these reasons that S. alterniflora has been transplanted worldwide. In China, S. alterniflora has been invaluable in storm surge protection and prevention of damages, as well as in land reclamation and filtration of pollutants (Wan 2009). S. alterniflora reproduces by two main routes: clonal reproduction by the formation of underground rhizomes and sexual reproduction by flowers to form seeds (Metcalfe et al. 1986; Trilla et.al. 2009). This makes S. alterniflora a formidable invader, quickly overtaking bare mud flats when introduced to new areas. There are downsides to the spread of S. alterniflora as well. In some locations S. alterniflora outcompetes native Suaeda, a seepweed or seablite, which draws tourists for the “Red Beach” it creates (Wan 2009). This eliminated the “Red Beach” landscape, thus deteriorating levels of tourism (Wan 2009). Competition between S. alterniflora and scrubby mangrove has also been noted, with S. alterniflora being the stronger competitor (Wan 2009).
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Wan, S., P., Qin, J. Liu, and H. Zhou. 2009. The positive and negative effects of exotic Spartina alterniflora in China. Ecological Engineering. 35:444–452.