dunes affected by overwash were completely eroded and the community response 



resembled that In comparison 1 (Fig. 35). Very few dunes were buried by ■* 



washover sand, although on a less-developed barrier beach, low dunes would be "j 



present and might be buried without erosion. Most salt marshes were buried by u 



deep deposits of sediment, and marsh vegetation did not recover. Vegetation jt 



did recover on a few areas near the edge of the washover fans, where sediment %' 

 had been reworked by the wind and tides. 



4. Species Response to Overwash Burial . .[ 



a. Introduction . Three types of sedimentation may affect plants on a 



barrier beaches: (T) burial by aeolian sand deposition in dunes during early 

 physical development; (2) burial of salt-marsh species by sand, silt, and 

 organic material carried by floodtides; and (3) burial of all plant species 

 on barrier beaches by overwash. Dune-building processes and the response of 

 the major dune species to aeolian sand deposition have been studied in detail - 



in the United States (.-toodhouse, 1978; Knutson, 1979) and in Europe (Phillips, 

 1975) to aid revegetation and stabilization programs in coastal areas. Nutri- 

 ent requirements, sand-trapping ability, and optimal planting strategies have 

 been determined for species capable of withstanding continual sand deposition 

 (Woodhouse, Seneca, and Broome, 1976). 



a 



Ammophila is one of the most studied of these dune-bulding plants; it has fe 

 reportedly grown through as much as 1.20 meters of sand accumulated in one 



growing season (Woodhouse, 1978). Rar.well (1958), in his study on British V 

 dunes, stated that while Ammophila arenaria (European beachgrass) can recover 



from at least 0.90 meter of aeolian sand burial in the course of a growing '• 



season, it probably cannot recover from an instantaneous burial of that £ 



extent. Knutson (1980) has studied northern dune-building processes on Naucet » 



Spit-Lasthain. Dunes 5 meters high and 100 meters wide were built by using snow £ 



ffincing and planting Ammophila brsviligulata over a 6-year period. In sesny § 

 cases, dune growth is not limited by the ability of the plant to grow through 

 deep sana burial, but by sand supply or the limited surface area which a plant 



has to trap windblown sand. Ammophila arenar»ia has repeatedxy h i reported u 



to grow best in areas of sand accumulation (Marshall, 1965; Tansley, 19b8; i 



Ranwell, 1975; Chapman, 197b; Huisk.es, 1979). * 



The accumulation of silt, sand, and organic r iterial in salt tsarahes has | 



been studied with relation to sea level rlsa (Ri'.rawell, 1958; Chapisaa, I960, £ 



1976; Redflt-ld, 1972). Ranwell (1975) developed a oodel to describe salt- f 



marsh sedtme. station in relation to tidal range, salt-marsh biotsass, suspended j* 

 silt levels, and elevation. Silt accumulation level is negatively correlated 

 to elevation in vegetated areas. Low marsh species experience greater, more 



consistent levels of sedimentation than higher marsh species. An accumulation S 



of as much as 20 centimeters of silt per year has be«n recorded in European | 



saarshes (Chapman, 1976) . Most major salt-sarsh grasses are able to keep pace &■ 



with sediment accumulation by vertical rhisossa extension. £■' 



I 



The response of grassland vegetation to overaash burial has been sC-sdled £ 



in North Carolina. Since overwash is cGoaaoa on 6oae of Koceh Carols.*. -»'8 | 



barrier islands, selei ion pressure has favored plant genotypes adapted to «■- 



overwash burial. Travis (1976) found that 24 speciea of flowering plots can Ja 



recover from overwash burial on the Outer Hanks of North Carolina. Godfrey ^ 

 and Godfrey (1974) used artificial burial boxes to demonstrate that Spartina 



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91 



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