receding slowly. This contradicts Kaplan et al. (1978) who claim 

 that the swamp is building to the south. Evidence for recession 

 can be seen in the unvegetated peat beneath the surface of the 

 river along the swamp border. In the vicinity of Bennett's Creek, 

 a thick peat, composed of only slightly decomposed rhizomes and 

 and roots, lies at a depth of six feet below the surface. Tussocks 

 of Carex stricta , the common grassy sedge of the swamp, stand on 

 submersed columns of interlaced rhizomes. These underwater pillars, 

 as much as 2 or 3 feet tall and each supporting a single clump of 

 sedge, have kept pace with sea level rise and could be a century 

 or two in age. 



Within the swamp, replacement of one of the major original 

 forest types, Atlantic white cedar, by other types after logging, 

 may be due to sea level rise. Earlier in this century, existing 

 stands were logged by Richmond Cedar Works and later by other 

 companies. These have been replaced largely by black gum ( Nyssa 

 sylvatica biflora ) and loblolly pine. Only single trees and very 

 small clusters of white cedar remain. Kaplan et al. (1978) found 

 that the cedar occurred on shallow peat over the tops of 

 submerged sand ridges (Fig. 14 ). It could be that these moist 

 sand ridges were occasionally dry enough in the past to support 

 the fire required for establishment of white cedar stands. 

 Examination of the swamp during the recent drought leads to the 

 impression that it is now impossible for these wet sites to ever 

 burn under the present moisture regime. It may be that a few 

 inches of sea level rise during the 60 or 70 years since the 

 last stands were established could be enough to convert the area 

 to more hydrophytic, non fire-dependent species. An interesting 

 series of vegetation changes must occur with the submergence of 

 sand flats and islands under peat. The range of forest types 

 present in the area suggest that the sequence may be as follows: 



lo High, well-drained mesic (beech-oak) or xeric (oak- 

 longleaf pine) sand ridges, with Pinus taeda around the 

 moist periphery. 



2. Less well-drained mesic (beech-oak) islands ringed 

 with Pinus taeda . 



3. Low, wet, peat-mantled sand ridges with the peripheral 

 Pinus taeda closing in over the top of the ridge as sea 

 level rises: stands of white cedar arising after drought- 

 induced fires. 



4. Site mantled with peat, with sea level too high^ to 

 permit fire. Vegetated with Pinus taeda , Nyssa sylvatica 

 biflora, red maple. 



5. Hydric site, permanently saturated, with sand ridge too 

 far beneath water table and peat to have any significant 



167 



