differences between these communities relate to their physiognomy, 

 which is a reflection of the biomass of one or two key dominants in 

 each community, not the presence of any unique plant assemblages. 



The planted bitter panicum community had one of the most depauperate 

 floras of any of the community types and its biomass (5.6 grams per 

 square meter) was the lowest measured in this study (Table 9), This 

 community appears to have been a generally unsuccessful planting 

 experiment. 



The sandgrass-buttonweed and the spurge-sandgrass communities differ 

 in the relatively high biomass of the former (68.7 grams per square 

 meter) and the low biomass of the latter (11.8 grams). The species 

 composition of the two communities agrees for six out of the seven 

 species sampled. The major differences between them however was quan- 

 titative (Tables 6 and 12) . Euphorbia polygonifol'ia (frequency 75 

 percent) was the most frequent species in the spurge-sandgrass community 

 while it ranked next to last (6.7 percent) in the sandgrass-buttonweed 

 community. Tviplasis purpurea and D. teres were, however, well dis- 

 tributed in both types. Whether these two types are separable into two 

 distinct communities is open to argument. Woodard (1974) has indicated 

 that the sandgrass community was experimentally fertilized. This could 

 be the reason for the measured biomass differences. All six communities 

 repeatedly occur near each other on all axes of the ordination, and two 

 probably belong to a continuation of types which show local variation 

 due to environmental or historical variability. 



It is felt, however, that for an intensive study on a relatively 

 small area such as the Duck Field Research Facility it is better to 

 draw out differences which might seem minor than to lose detail in 

 overgeneralization. For this reason, each of the 11 defined communities 

 has been kept separate. 



The results of these studies have raised many interesting questions. 

 Our observations suggest that the successional theories of Wells (1928 

 and 1938) be closely examined and perhaps reformulated. Questions have 

 also been raised as to the future development of each of the delimited 

 communities. Which species are likely to increase in importance, and 

 which will decline? Especially interesting is the future of the 

 planted and the sound-side disturbed communities. 



76 



