2. Other Environmental Factors . 



Salinity is a major stress on all plants growing within the intertidal 

 zone. However, the species specified for use in this report are all salt 

 tolerant. The salinity tolerance range for each species is presented in the 

 following section on planting guidelines. 



Soil type will mainly affect the planting technique and need for ferti- 

 lizer since most salt marsh plants tolerate a wide range of substrates. The 

 actual planting will be easier in loose sandy soils than in heavy plastic or 

 very compact soils. 



Strong tidal action can undermine plantings; therefore, location and 

 migration of tidal channels in the vicinity of prospective plantings should be 

 considered. 



The presence of healthy marsh patches on or near the site is an excellent 

 indicator that there are no environmental factors which are likely to limit 

 plant establishment at the site. 



IV. PLANTING GUIDELINES 



1. Selecting Plant Species. 



For erosion control projects, the intertidal zone is the most critical 

 area to be planted and stabilized. If a healthy band of intertidal marsh can 

 be established along a shore, revegetation of the slope behind it will occur 

 through natural processes. Four species of pioneer plants have demonstrated 

 potential in stabilizing the part of the intertidal zone which is in direct 

 contact with waves: smooth cordgrass (Spavtina altermiflova) along the gulf 

 and Atlantic coasts, Pacific cordgrass (Spavtina foliosa) on the Pacific coast 

 from Humboldt Bay south to Mexico, and Lyngbye's sedge (Carex Lyngbyei) and 

 tufted hairgrass (Desahampsia eaespitosa) in the Pacific Northwest. 



2. Site Preparation. 



The width of the substrate at an elevation suitable for plant establish- 

 ment will determine in part the relative effectiveness of the erosion control 

 planting. A practical minimum planting width for successful erosion control 

 is 20 feet (6.0 meters) (Knutson, et al., 1981). On the Atlantic and gulf 

 coasts, marsh plants will typically grow in the entire intertidal zone. Marsh 

 plants seldom extend below the elevation of mean tide on the southern Pacific 

 coast or below lower high water in the Pacific Northwest. Because of these 

 elevational constraints, the more gradual the shore slope, the broader the 

 potential planting width. On steeply sloping shores, there may be little area 

 suitable for planting. If the potential planting area is not 20 feet in 

 width, the shore must be sloped or backfilled to extend it. Backfilling must 

 be done enough in advance of planting to allow for settling and firming. 



Salt marsh plants rely heavily on exposure to direct sunlight and will not 

 grow in shaded areas. Therefore, any overstory of woody vegetation present at 

 a site should be cleared above the planting area and landward to a distance of 

 10 to 15 feet (3 to 5 meters). 



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