Table 8. Percentage of organic matter 

 in selected wetland and upland soils. 



Sites 



Organic matter 

 (%) 



References 



Woodwell 1958 

 Woodwell 1958 

 This study 



Long et al. 1969 

 Perkins et al. 1962 

 Perkins et al. 1962 



Some zones (see Appendix) are roughly 

 comparable in calciuR' concentrations 

 (660 ppm) to a tulip poplar forest (Shu- 

 gart et al. 1976), which is considered 

 eutrophic (Jordan and Herrera 1981). Some 

 floodplain sites (blackwater Zone IV, 

 alluvial Zone V) approach oligotrophy 

 (44-75 ppm Ca). In the study area, the 

 lowest nutrient levels occur in Zone V. 



There are marked differences in 

 organic matter concentrations among the 

 various zones. Some zones (II and black- 

 water IV) have low nutrient availability 

 due to "lock up" of nutrients in organic 

 matter. This condition occurs particularly 

 in swales and peat-forming soil types. 

 Periodic drydown is very important to 

 nutrient release from organic matter and 

 litter. When drydown is rare or aperiodic 

 (as in the specific zones above), nutri- 

 ents tend to be bound in complexes with 

 organic matter. On other sites nutrient 

 concentrations are low as a result of a 

 lack of inorganic inputs (as in remote 

 swales adjacent to the upland). In black- 

 water rivers, nutrients n:dy be complexed 



and exported as particulates or refractory 

 humic substances. 



Soil micronutrient concentrations 

 tend to be high, especially in acidic 

 sites, although this may depend on the 

 amount of inorganic input, or distance 

 from the channel (Appendix). Cobalt stor- 

 age by swamp tupelo (Eyde 1966) and the 

 high zinc demand of cultivated pecan trees 

 suggest that some floodplain vegetation 

 may accumulate or need high levels of 

 micronutrients. 



The precise relationship between 

 soils and vegetational responses in flood- 

 plains is unresolved. It is unknown, for 

 example, why the low-nutrient, low-organic 

 flats of the Oconee support a magnificent 

 willow oak stand, or why the old growth 

 diamondleaf oak on Turkey Creek has the 

 lowest organic matter of any Zone IV 

 floodplain. Equally challenging is why 

 the mineral-rich Taw Caw silty clay loam 

 of the virgin Congaree Swamp National Mon- 

 ument supports extensive Zone IV wet flats 

 with few or no large trees. 



30 



