Assessing the vegetation history of three Southern Appalachian balds through soil organic matter analysis
The history of Southern Appalachian grassy balds has long been a topic of speculation. Two types have been identified: those completely covered by grass and those occupied by a mixed-hardwood overstory with a grassy herbaceous layer. Three areas historically known as balds were identified in the Wine Spring Ecosystem Project Area. Each is currently under a different management regime. The objective of this assessment was to determine the vegetative history of these balds through soil organic matter (SOM) analysis. Soil was collected from each horizon through the profile on the bald sites using a nearby forest for reference. The d13C values were determined for the green vegetation, litter, and soils of the bald sites and reference forests. Samples were selected for determination of phytolith and charcoal content and for 14C dating. The d13C value of plant tissues varies with photosynthetic pathway and plant type, providing a distinctive signature in SOM. Significant shifts in SOM d13C values with depth in the profile would suggest changes in site vegetation. Organic matter analysis indicated that two of the bald sites were never completely covered by grass without a woody component. The third bald may have undergone a vegetative shift in more recent times. Data also suggest that a vegetative shift may have occurred on two of the reference forest sites.