3. Vegetative Differences Between Planted Dunes and Naturally 

 Forming Dunes . 



When the area behind naturally forming foredunes is compared 

 to the planted foredunes, there is an obvious appearance of a more 

 arid environment in the unplanted natural dune area [Fig. 25) . 

 The more mesic microclimate bayward of experimental plantings is 

 believed to be due to the damming effect provided by the resultant 

 dunes. These dunes retain rainwater in the middune area, providing 

 a more favorable habitat and becoming more free of salt spray than 

 the area behind the unplanted naturally forming dune. The obvious 

 differences as reflected by the vegetation measurements are as 

 follows : 



(a) The perennial grasses (bitter panicum, seashore 

 dropseed, and sea oats) are found only occasionally 

 in and behind the unplanted dune area, but are common 

 behind the other dunes. The sea oats is increasing 

 rapidly in all but the unplanted area (Table 11). 



(b) Gulf croton is quite common on the unplanted study 

 area, but nearly absent behind the planted study areas, 

 Gulf croton is believed to be a very drought tolerant 

 species and in this case one indicative of a more 

 arid microenvironment . 



(c) Beach evening primrose and beach morning glory were 

 apparently at home in both environments. 



(d) The Fimbristylis species, HydroGotyle bonariens-is , 

 and Baoopa monnievi. all apparently require a more 

 mesic habitat; they were only found in low areas 

 behind the dunes. Their near absence (Table 11) 

 from the unplanted study area is also believed 

 indicative of relative aridity among the experimental 

 sites. 



55 



