range occur in North Carolina estuaries where tidal fluctuations are 

 dominated by wind direction and velocity and where salinities are low. 

 At our Snow's Cut experimental site the salinity ranges from 7 to 10 parts 

 per thousand. Under this low salinity, freshwater plants have become 

 mixed with the S. alterniflora from about half way in the intertidal zone 

 upward. In completely freshwater, plant species adapted to freshwater 

 would probably become dominant. 



In several North Carolina estuaries the range of periodic tides is 

 quite low because of few, narrow inlets and the large area of the estua- 

 ries. In such estuaries, surface fluctuations are greatly affected by 

 wind direction and velocity, and consequently, changes in surface levels 

 occur irregularly. This complicates the relationship between tide range 

 and the elevation zone occupied by S. alterniflora. In many locations, 

 S. alterniflora occurs as a narrow fringe at the water's edge. When 

 planning marsh restoration, it is best to take elevation readings of the 

 upper and lower limits of nearby natural marshes and plan to plant within 

 this zone. In preparing a site, the area available for planting can be 

 increased by making the slope as gentle as practicable without ponding 

 of water. The more gentle the slope the larger the area which will be 

 alternately flooded and drained. 



b. Substrate Texture . Several substrate-related factors affect 

 propagation of S. alterniflora. Texture of the substrate as it affects 

 bearing capacity is an important practical consideration. Substrates 

 with high proportions of silt and clay are not suitable for conventional 

 planting equipment. The Straits test site is the only place where this 

 problem was found. Most of the dredged material in North Carolina 

 estuaries is composed mostly of sand, and consequently has excellent 

 physical properties. Additional opportunities to experiment with propa- 

 gation methods on finer textured materials will be welcome. 



Sandy substrates are not without limitations. Sandy materials are 

 inherently less fertile than silt and clay since fewer mineral nutrients 

 are adsorbed. Experiments with fertilizers have produced increased 

 growth through applications of nitrogen and phosphorus at locations where 

 the substrate is sandy, such as Drum Inlet and Ocracoke Island. An 

 exception is the Snow's Cut location where the substrate is sand, but 

 nutrients are apparently supplied by the large amount of silt and clay 

 sediments carried by the Cape Fear River and deposited in the marsh on each 

 tidal cycle. At Ocracoke and Drum Inlet little deposition of fine materials 

 has been observed. 



c. Salt Damage . Another substrate-related factor is salinity. 

 Although S. alterniflora is exceptionally well adapted to growth and sur- 

 vival under saline conditions, it can suffer serious salt damage. This 

 damage we observed in several instances during the field studies. All 

 observations were in the Pamlico and Core Sound region on sites subject 



to wind setup. Salt damage may occur in such areas any time that extended 

 periods of low water coincide with periods of warm, clear weather. Under 

 these conditions surface salinities build up rapidly and can be particularly 



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