Of particular interest to this study is the vegetation of the 

 backshore and the foredune fores lope, and the natural succession 

 of plants from a barren, hurricane-planed backshore to a continuous, 

 mature foredune ridge. Sea purslane {Sesuvium povtulaaastvum') , 

 one of the first species to re-appear on the denuded backshore, 

 is vegetatively dispersed by wave and wind action. Clumps of sea 

 purslane trap sand, forming small dunes which rise only a few 

 feet above the beach surface. Beach morning glory [Ipomoea 

 stolonifeva) , railroad vine, gulf croton, sea oats, saltmeadow 

 cordgrass, bitter panicum, and seashore dropseed are early colon- 

 izers (Dahl, et al . , 1975). 



Rhizomatic growth and tillering of these grasses, especially 

 sea oats and bitter panicum, are stimulated by the accumulation 

 of fresh sand continually blown inland from the shore. Windblown 

 sand is trapped by exposed grass blades and eventually stabilized 

 by the root and rhizome system. Fed by fresh beach sand blowing 

 inland, the unconnected hummock dunes of sea oats, bitter panicum, 

 saltmeadow cordgrass, and seashore dropseed continue growing and 

 eventually interconnect, forming a dune ridge. New hummock dunes 

 begin forming shoreward, and in this manner, the foredune grows 

 toward the gulf. This shoreward growth eventually eliminates 

 fresh sand accumulation on the rear of the dune ridge, and affords 

 additional protection from wind and salt spray. Less salt-tolerant 

 species and species not adapted to growing in accumulating sand 

 then become established; e.g., seacoast bluestem, gulfdune 

 paspalum, broom groundsel {Senecio rn-ddelU-i) , and beach ground- 

 cherry (Dahl, et al., 1975). 



The time scale for these sequences is dependent on the 

 intervals between storms, the severity of previous storm damage, 

 the proximity of undamaged colonizing species, and the precipitation 

 cycle. The area containing the present study plots was barren 

 in 1937, but by 1948 a vegetated foredune ridge had appeared with 

 a vegetated plain to the west. By 1967, after Hurricanes Carla 

 and Beulah, the dune ridge was absent, and the area was again barren 

 with a field of active sand dunes migrating west. 



III. METHODS: EXPERIMENTAL PLOTS 



1 . Experimental Plots . 



A summary of the experimental plots is given in Table 1 which 

 corresponds with the study site map in Figure 3. These experimental 

 plots and an unplanted naturally forming dune area are also included 

 in Appendix A which shows exact measurements referenced to two 

 surveyed base lines (east and west). 



