alterm'flora , Spartina patens , mixed herbaceous, Myrica-Ilex - Quercus 

 shrubs, Persea-Ilex-Quercus shrubs and the maritime live oak forest. 

 Also characteristic of the coastal area are the estuarine Juncus 

 roemerianus and Spartina -Distich! is-Sal icornia communities as well 

 as the dune grass Uniola paniculata . 



The structure of the spider populations was determined for each of 

 these communities with the exception of the forest climax. The 

 investigation was carried out at Beaufort, N. C, during 1951 and 

 1952. A total of 139 species of spiders belonging to 24 families were 

 collected in the maritime communities. Each community was found to display 

 a distinct population structure of spiders characterized both by the 

 presence of certain species and by the relative density which each exhibits. 



Sampling in ten different stands of Spartina alterniflora and in 

 one stand over a two-year period indicates that the population structure 

 of spiders living in this community exhibit a constancy not only in 

 space but also in time. Thus, the abstract Spartina alterniflora 

 community supports an abstract spider population that is essentially 

 the same as that in any one concrete stand. 



The three estuarine intertidal communities that occur in distinct 

 zones support closely related spider populations, but the structure that 

 each exhibits is sharply different. The dune community of Uniola is 

 the most xeric of the maritime communities. This environment is reflected 

 in the xeric species of spiders that the community supports, many 

 of which are also characteristic species of the dry sand beach drift 

 lines. 



The zonation and succession of maritime vegetation produce a zonation 

 and succession of spiders beginning in the intertidal communities 

 and ending in the maritime forest. This succession, in general, 

 is characterized by an increasing number of species and population 

 density with proximity to the maritime climax. This may, in turn, be 

 correlated with the increase in stratification of the intracommunity 

 environment and the greater number of ecological niches afforded by 

 the vegetation. (G.S.) 



Keywords: spiders, marshes, community structure. North Carolina 



V-D-10 



Smalley, A.E. 1959. The role of two invertebrate populations, Littorina 

 irrorata and Orchelimum fidicinium , in the energy flow of a salt marsh 

 ecosystem. Ph.D. Thesis. University of Georgia. 135 pp. (Diss. 

 Abstr. 20:2979-8). 



Energy relationships of three components of a salt marsh on the 

 Georgia coast were studied: (1) Spartina alterniflora , the only 

 higher plant occurring on the marsh, (2) Littorina irrorata , a snail 



259 



