Assessing the Vegetation History of Three Southern Appalachian Balds through Soil211 Organic Matter Analysis

摘要

The history of Southern Appalachian grassy balds has long been a topic of211u001especulation. Two types have been identified: those completely covered by grass 211u001eand those occupied by a mixed-hardwood overstory with a grassy herbaceous layer. 211u001eThese areas historically known as balds were identified in the Wine Spring 211u001eEcosystem Project Area. Each is currently under a different management regime. 211u001eThe objective of this assessment was to determine the vegetative history of these 211u001ebalds through soil organic matter (SOM) analysis. Soil was collected from each 211u001ehorizon through the profile on the bald sites using a nearby forest for 211u001ereference. The values were determined for the green vegetation, litter, and soils 211u001eof the bald sites and reference forests. Samples were selected for determination 211u001eof phytolith and charcoal content and for (sup 14)C dating. The value of plant 211u001etissues varies with photosynthetic pathway and plant type, providing a 211u001edistinctive signature in SOM. Significant shifts in SOM values with depth in the 211u001eprofile would suggest changes in site vegetation. Organic matter analysis 211u001eindicated that two of the bald sites were never completely covered by grass 211u001ewithout a woody component. The third bald may have undergone a vegetative shift 211u001ein more recent times. Data also suggest that a vegetative shift may have occurred 211u001eon two of the reference forest sites.