PROFILES THROUGH MAJOR PEAT BOG 

 E3 HUMIC POCOSIN PEAT 

 g FIBROUS WHITE CEDAR PEAT 

 E3 PEATV SAND AND SAND 



05 



1 MILE 



r OFT 



2 



4 



-6 



'-8 



Figure 22. Substrate cross section through a pocosin formerly dominated by Atlantic white cedar (Croatan 

 National Forest, North Carolina) (modified from Otte 1981). 



The soil temperature regimes in which 

 cedars grow are Frigid (Maine); Mesic (New 

 Hampshire to Delaware and Maryland) ; and Thermic 

 (Virginia to Florida and Mississippi). 



Appendix C lists the criteria of the USDA Soil 

 Conservation Service for hydric soils and for distin- 

 guishing organic from mineral soils. A complete list 

 of hydric soils in "Hydric Soils of the United States" 

 (USDA CS 1985a) includes information on the 

 temperature regime; drainage class; depth and 

 months of high water table; and frequency, duration, 

 and months of flooding. Soil unit maps suitable for 

 field work are prepared at the county level and may 

 be obtained from state Agricultural Experiment Sta- 

 tions, local offices of the Soil Conservation Service, 

 the Extension Service, and Soil and Water Conserva- 

 tion Districts. 



Cedar histosols are high in organic content, 

 cation exchange capacity, water holding capacity 

 and water content per unit volume, and low in ash 

 content, bulk density, hydraulic conductivity, and 

 available nutrients. Cedar peat is a rich red-brown. 

 Aspects of the relevant characteristics of organic 

 soils are discussed by Gorham (1 987) ; Hemond et al. 

 (1987); Ingram and One (1981); Leighty and Buol 

 (1983); Otte (1981); Richardson et al. (1978). 



4.4 PRODUCTION AND DECOMPOSITION 



Day (1987) reviewed all research until 1984 

 on organic production and decay in Atlantic white 

 cedar wetlands. This work was done primarily by 

 Day and his colleagues (e.g., Dabel and Day 1977; 

 Day 1982; Gomez and Day 1982) on a mixed 

 Chamaecyparis/re6 maple/black gum site in the Vir- 

 ginia section of the Great Dismal Swamp. 



The total aboveground biomass, fine root bio- 

 mass, and aboveground net primary productivity 

 for the four different Dismal Swamp forest commu- 

 nities measured all exhibited intermediate values 

 for swamps in general ( for comparative data, see 

 Day, unpubl.). The annual foliage turnover (litter- 

 fall/biomass) for Chamaecyparis is 35%, a typical 

 conifer value. The relatively large litter mass, slow 

 decomposition rate of both cedar needles and total 

 litter, and high concentration of tannins (4.19%) and 

 lignins (19.94%) in cedar foliage correlate well with 

 the observed accumulation of peat in cedar wetlands 

 (Day 1 987 and unpubl.) (Both lignins and tannins are 

 believed to inhibit decay [Melillo et al. 1 982; Cameron 

 and LaPoint 1978].) 



4.5 SOIL AND PLANT TISSUE CHEMISTRY 



Whighamand Richardson (1988), in a recent 

 study of the chemistry of a minerotrophic Maryland 

 cedar wetland bordering a tidal creek, found cedar 

 leaf tissue to be significantly higher in Ca, Al, Pb and 

 Sr - and poorer in N and P - than other plants as- 

 sociated with it (Table 5). These differences indicate 

 differential uptake and exclusion mechanisms in 

 Chamaecyparis metabolism. Whigham and 

 Richardson (1988) and Bandleand Day (1985) found 

 that soil of cedar-dominated wetlands has higher Ca, 

 Mg, Al, and Fe levels, and lower P content than sur- 

 rounding wetlands; Whigham and Richardson ob- 

 served that Atlantic white cedar sites are R K, and 

 possibly N limited. 



Richardson (1985) showed that in acid wet- 

 land soils, available P levels are apparently controlled 

 by extractable Al and Fe. The suite of cations thus far 

 found in cedar soils is consonant with this view 

 (Whigham and Richardson 1988). 



33 



