Knowledge about vegetation dynamics during the last glacial and deglacial periods in southeastern North America is under-constrained owing to low site density and problematic chronologies. New pollen records from two classic sites, Anderson Pond, TN, and Jackson Pond, KY, supported by AMS 14C age models, span 25.2-13.7ka and 31.0-15.4ka, respectively. A transition from Pinus dominance to Picea dominance is recorded at Jackson Pond ca. 26.2ka, ~coincident with Heinrich Event H2. Anderson and Jackson Ponds record a transition from conifer to deciduous-tree dominance ~15.9 and 15.4ka, respectively, marking the development of no-analog vegetation characterized by moderate to high abundances of Picea, Quercus, Carya, Ulmus, Fraxinus, Ostrya/Carpinus, Cyperaceae, and Poaceae, and preceding by ~2000yr the advent of similar no-analog vegetation in glaciated terrain to the north. No-analog vegetation developed as a time-transgressive, south-to-north pattern, mediated by climatic warming. Sporormiella abundances are consistently low throughout the Jackson and Anderson Pond records, suggesting that megafaunal abundances and effects on vegetation varied regionally or possibly that the Sporormiella signal was not well-expressed at these sites. Additional records with well-constrained chronologies are necessary to assess patterns and mechanisms of vegetation dynamics during the last glacial and deglacial periods.
Bibliographical noteFunding Information:
This research was supported by National Science Foundation, Grant DEB-0716951 . Landowners Harold Gene Leonard and Allan Jackson kindly provided access to Anderson and Jackson Ponds, respectively. We appreciate the efforts of Mark Lesser, Meghan Taylor, Mike Urban, Jim Kocis, Ron Counts, and Scott Waninger in the field, and Rachel Jones, John LeValley, Danielle Reid, Robert Joyce, Reid Olson, Nancy Van Dyke, Haley Olsen, and John Bruno in the laboratory. We thank Maarten Blaauw, Simon Brewer, Jacquelyn Gill, Sally Horn, and Rachel Jones for discussion, and two anonymous reviewers for critical comments. We are particularly indebted to Jacquelyn Gill for cross-checking several samples to confirm paucity of Sporormiella spores. All pollen, macrofossil, and radiocarbon data have been deposited with the Neotoma Paleoecology Database ( www.neotomadb.org ).
Copyright 2013 Elsevier B.V., All rights reserved.
- Anderson Pond
- Glacial and deglacial periods
- Jackson Pond
- No-analog vegetation
- Pollen records
- Southeastern North America