X AXIS 



Figure 131. Ordination of 15 belts on North Beach. 



Belt D also groups with the older belts on North Beach (group II). This 

 area, which was barren sand in 1938, has developed all the major barrier com- 

 munities in only 40 years. Of particular interest is the highly diversified 

 salt marsh at belt D. Spartina aitemi flora biomass is low with many associ- 

 ates. The dunes at belt D are 6 meters high and broad as a result of rework- 

 ing of the 1938 washover. 



Belt I also generally groups with the older belts (group II). Although 

 this belt has formed within the last 50 years, it. has well-developed shrub and 

 grassland communities. Armr.ophilo. bveviligulata in the dune community has the 

 highest productivity sampled on North Beach. This dune community completely 

 overwashed in 1978. 



Group III (belts C, H, K, and Z) fall in an intermediate position between 

 the young belts (group I) and the older belts (group II). Belts G and K have 

 developed since 1952, and belt H, although initially formed in the 1930' s, was 

 partially overwashed in 1978. All three belts have a mixture of poorly and 

 well-developed dunes. Salt marshes are restricted to localized areas. Be.lt G 

 differs from all other areas because it has a very broad zone with depauperate 

 dune vegetation. This massive washover in 1952 received substantial inputs of 

 sand from overwash until the 1960's when the dune field became continuous. 

 The embryonic dunes, formed on the back barrier, rapidly deflated, resulting 

 in the senescence of Ammophila breviligulata. This belt, which was formed 

 similarly to belt D, does not appear to be developing in the same manner. 

 It is possible that at belt D, overwash continued for many years allowing 

 substantial oack dunes to form, and that rapid dune development at belt G, 



211 



