AGE STRUCTURE AND POSSIBLE ORIGINS OF OLD PINUS-TAEDA STANDS IN A FLOODPLAIN FOREST

Stand structure and ages were measured in six old stands of Pinus taed a L. (loblolly pine) and one younger stand within Congaree Swamp Natio nal Monument, South Carolina. Dominant overstory species included lobl olly pine, shade intolerant hardwoods and tolerant hardwoods. All over story species except pine also occurred in the sapling layer Five of t he six old stands had two or more pine age classes. All but one indivi dual pine was less than 200 years old. According to estimates of futur e survival, current loblolly pine seedling densities in recently hurri cane-disturbed and clearcut areas are inadequate to reproduce tree den sities measured in extant old stands. Spatial distributions of mature trees suggest that pines have established in gaps as large as 0.3 ha a nd as small as a single overstory tree. No evidence of fire (scars on existing trees or charcoal in the upper 10 cm of soil) was found in an y old stand. From these results, we speculate that the old loblolly pi ne stands in Congaree Swamp resulted from small-scale agricultural act ivities, although wind storms, fires, or combinations of these may hav e played contributing roles. Because of its apparent ability to regene rate in gaps, loblolly pine will probably remain in Congaree Swamp for several centuries as small clumps and scattered individuals.