PRELIMINARY CARBON STABLE ISOTOPE ANALYSIS OF MONOCOTS AND POLLEN DIVERSITY IN HOLOCENE PEAT DEPOSITS IN CONGAREE NATIONAL PARK

The Congaree National Park, located near Columbia, SC., contains the oldest floodplain forest in North America. The floodplain muckswamp contains portions of the original channel of the nearby Congaree River as well as extensive peat deposits. A three-meter long peat core was extracted from the muck swamp containing a basal date of 21,000 kyr. Previous palynological investigations have identified several major shifts in dominant plant assemblages since that time. The abundance of diatoms near the base of the core suggests initial deposition in a paleomeander of the river system where the peat finally began to accumulate in a resulting oxbow lake environment. Based on previous pollen diversity studies on these peat deposits, the dominant terrestrial ecosystems transitioned from a spruce, hemlock and herbaceous plant assemblage, through a system dominated by sweet gum, holly, hickory, elm, pine, sedges, ferns and mosses. Finally, the ecosystem was dominated by deciduous forest containing the above hardwoods and herbaceous plants with an abrupt decline in pines. These shifts in vegetation suggest several warming intervals throughout the history of the region. While much of the material in the peat core is heavily decomposed, we have extracted preserved monocot leaf and sheath material at various intervals throughout the core. Here, we present our initial record of δ¹³C analysis from the monocot and bulk peat material in an attempt to gain further insight into climate variability in the Southeastern US since the last ice age.