is shown in Figures 6-34 and 6-35 . This phenomenon has not occurred with the 

 sea oats plantings at Core Banks, North Carolina (Fig. 6-36), or at Padre 

 Island, Texas (Fig. 6-37). 



The rate of spread for American beachgrass has averaged about 1 meter per 

 year on the landward side of the dune and 2 meters per year on the seaward 

 slope of the dune as long as sand has been available for trapping (see Figs. 

 6-34 and 6-35). The rate of spread of sea oats is considerably less, 30 

 centimeters (1 foot) or less per year. 



Figure 6-35 shows an experiment to test the feasibility of increasing 

 the dune base by a sand fence in a grass planting. The fence was put in the 

 middle of the 30-meter-wide (100-foot) planting. Some sand was trapped while 

 the American beachgrass began its growth, but afterwards little sand was 

 trapped by this fence. The seaward edge of the dune trapped nearly all the 

 beach sand during onshore winds. The landward edge of the dune trapped the 

 sand transported by offshore winds blowing over the unvegetated area landward 

 of the dune . 



200 



30 



(m) 

 Disfonce from Bose Line 



Figure 6-34. American beachgrass dune, Ocracoke Island, North Carolina, 



6-49 



