Seedling Establishment of Spartina alterniflora and Spartina patens on Dredged Materials in Texas

Effects of fertilizer, elevation, and tidal inundation on seedling establishment of Spartina alterniflora and Spartina patens were tested at a wave-protected sandy dredged material site, Galveston Bay, Texas. No seedlings that grew from sown seeds became established at elevations below 36 cm (msl) while the greatest number established in the upper tier. Seedlings of S. alterniflora were more numerous than S. patens in the upper and middle tiers. Naturally occurring seedlings of S. alterniflora, which apparently germinated from seeds produced on transplants in adjacent plots, established at all elevations of the site during winter. The average time of tidal inundation at a particular elevation was less during winter than spring. Thus, establishment of plants by seed at low intertidal elevations appears feasible only during low seasonal winter tides and with S. alterniflora. Fertilizers did not enhance growth, and high concentrations of fertilizer caused stress to some S. alterniflora seedlings