TABLE 2-2 



SUMMARY STATISTICS FOR ELEVATIONS OF MARSH PLANT SPECIES 



'Excludes anomalous values in some cases and observations covering less than 2 percent of transect. 

 ' 'Recommended indicator species. 



While this profile is by no means precise, it gives some insight into the expected habitat for a 

 given elevation and the tolerances various species have for flooding. For example, it establishes 

 the general lower limit of marsh for Charleston, where it is presumed that too frequent flooding 

 kills low-marsh species and transforms the marsh to unvegetated mud flats. 



The low-marsh plant Spartina alterniflora was the most dominant species, making up 69 

 percent of the composite transect. Its modal elevation was 75 cm (2.45 ft), close to today's neap 

 high tide. For Charleston, this is about 15 cm (0.5 ft) below mean high water. Figure 24 shows 

 that S. alterniflora extends beyond the limits of low marsh into both high marsh and tidal flat; 

 however, this species occurs primarily at low-marsh elevations. 



The other indicator species are generally considered to be high-marsh species. These 

 include Distichlis spicata, Borrichia frutescens, Limonium carolinianum and Salicomia virginica. 

 Spartina patens, while having been found to coexist with Distichlis spicata in Maryland and 

 North Carolina marshes (E.C. Pendleton, personal communication, December 1984), is 

 uncommon in Charleston at elevations less than 122 cm (Scott, Thebeau, and Kana 1981). The 

 apparent inconsistency in these observations may be related to the significant difference in tidal 

 range between central South Carolina and North Carolina. 



Area Estimates 



Two sources of information were available for land area estimates: United States Geological 

 Survey (USGS) 7.5-minute quadrangles and digitized computer maps prepared in an earlier EPA- 

 sponsored case study (Kana et al. 1984). Using topographic and contour maps, we estimated the 

 number of acres of each habitat in the Charleston area (see Figure 2-1). 4 



Our results were graphically determined and spot-checked by a second investigator to ensure 

 they were consistent to within ±15 percent for each measurement. Thus, the error limits for the 

 overall study area are estimated to be a maximum of ±15 percent by subenvironment. 5 



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