areas with a tidal amplitude of less than 2.0 meters. In the northern Pacific 

 coast (Fig. 1) most of the intertidal zone lacks marsh vegetation because of 

 the influence of large tidal ranges and the absence of suitable adapted 

 species. Marshes are rarely found below the elevation of mean lower high 

 water (MLHW) in this region. 



Even when plants can be established throughout much of the intertidal 

 zones, as is the case on many of the Atlantic coast marshes, the potential 

 width (landward to seaward) of a particular planting depends on the tidal 

 amplitude and shore slope. Broader marshes can be established coincident with 

 greater tidal ranges and more gradual sloping shorelines. 



d. Sediment Supply. Rapidly prograding salt marshes normally occur only 

 in the presence of an abundant sediment supply. However, healthy salt and 

 brackish marshes are found under a very wide range of sediment conditions. 

 Removal of some sediment from a marsh shoreline is usually inevitable during 

 storm periods. For such areas to remain stable this lost material must be 

 recaptured from time to time, e.g., at regular intervals, between storm 

 events, or seasonally as the result of wind-driven or tidal currents. Sedi- 

 ments may move in suspension or as bedload. There are no guidelines at 

 present for evaluating the sediment supply of prospective planting sites. 



e. Summary . 



(1) Soil Type . Salt marsh plants are tolerant to a wide variety of 

 soil types. However, soil type often dictates the choice of planting and 

 fertilization procedures that will be necessary. 



(a) Cohesive Sediments (Clays). Cohesive sediments provide a 

 stable planting surface and are low in nutrients if highly weathered and are 

 more difficult to plant than loose sandy substrates. 



(b) Sandy Sediments . Sandy sediments may provide an unstable 

 planting surface if subject to high wave activity, are low in nutrients, and 

 are easy to plant if not compacted. 



(2) Salinity . Suitable plants may be found which can be established 

 in salinities up to about sea strength (35 parts per thousand). 



(3) Oxygen-Aeration . Most marsh species are adapted to anaerobic 

 conditions . 



(4) Exposure to Direct Sunlight . The overstory of woody vegetation, 

 if present, should be cleared above the planting area and to a distance of 3 

 to 5 meters landward. 



(5) Shore Width Available for Planting . A practical minimum planting 

 width for erosion control planting is about 6.0 meters. 



(6) Sediment Supply . The sediment supply is beneficial to marsh 

 stability but difficult to quantify. 



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