Generally, the swamp forest subcanopy consists of 

 smaller individuals of swamp blackgum and red maple, with 

 an occasional sweet bay. This stratum is not we 11 -developed, 

 except as noted where bald cypress forms the true canopy. 

 The shrub layers of the swamp forest are rather open and 

 are generally occupied by one or two species. A tall shrub 

 layer of red bay (Persea borbonia ) is locally present, 

 ranging in height from 15-20 feet. Sweet pepperbush 

 ( Clethra alnifolia ) and fetterbush ( Lyonia lucida ) are 

 usually the dominant low shrubs; bitter gallberry ( Ilex 

 glabra ) and highbush blueberry ( Vaccinium corymbosum ) 

 are scattered. Ground cover is absent except for sphag- 

 num mats. The ground surface is wet, with shallow standing 

 water present in local depressions during winter and spring. 

 Cypress knees (to 2 feet tall) and many fallen logs add to 

 the rough and hummocky surface pattern. 



Two main community types are designated in the swamp 

 forest portions of the natural area, based on the features 

 summarized in the preceding discussion. Occupying most of 

 the swamp forest sites is a community consisting of Nyssa 

 sylvatica var. biflora- mixed lowland conifers/ Per sea bor- 

 bonia/Clethra alnifolia-Lyonia lucida (Swamp black gum- 

 mixed lowland conifers/Red bay/Sweet pepperbush-fetterbush; 

 CT 1) ; bald cypress is usually present but reduced in im- 

 portance due to past cutting. The second community type 

 occurs where bald cypress is still dominant: Taxodium 

 distichum/Nyssa sylvatica var. biflora- mixed lowland con- 

 ifers/Perse^ borbonia/Clethra alnifolia-Lyonia lucida (Bald 

 cypress/Swamp black gum-mixed lowland conifers/Red bay/ 

 Sweet pepperbush-fetterbush; CT 2) . Both these community 

 types are correlated with the Pungo soil series which is 

 the predominant soil mapping unit in the Alligator River 

 natural area. 



The average height and trunk diameters of these two 

 community types varies considerably within the natural 

 area. Generally the swamp blackgum-mixed conifer (CT 1) 

 stands range from 60-75 feet in height and have average 

 dbh values of 12-18 inches. Scattered trees of 24 inches 

 dbh and higher are usually present. The baldcypress 

 dominated stands are usually taller (75-90 feet) and 

 have average dbh values of 14-20 inches, sometimes more. 

 Atlantic white cedar is widely distributed throughout the 

 natural area and is found in two distinct physiognomic 

 forms. Over much of the area is occurs as scattered 

 medium to old-growth trees either in the subcanopy or 

 canopy layers. It may reach 25%-50% relative dominance 

 on these sites. In some areas it occurs as a distinct 

 even-age monospecific community ( Chamaecyparis thyoides/ 

 mixed shrubs (Atlantic white cedar /mixed shrubs; CT 3) , 



19 



