Assessing linkages among the late-glacial megafaunal collapse, novel plant communities, and fire in eastern North America using the dung fungus Sporormiella

2012 ◽  
Vol 279-280 ◽  
pp. 168
Author(s):  
Jacquelyn Gill
Nature ◽  
1993 ◽  
Vol 363 (6425) ◽  
pp. 188-188 ◽  
Author(s):  
André J. Levesque ◽  
Francis E. Mayle ◽  
Ian R. Walker ◽  
Les C. Cwynar

1980 ◽  
Vol 13 (1) ◽  
pp. 111-132 ◽  
Author(s):  
Paul A. Delcourt ◽  
Hazel R. Delcourt ◽  
Ronald C. Brister ◽  
Laurence E. Lackey

AbstractNonconnah Creek, located in the loess-mantled Blufflands along the eastern wall of the Lower Mississippi Alluvial Valley in Tennessee displays a sedimentary sequence representing the Altonian Substage through the Woodfordian Substage of the Wisconsinan Stage. The site has a biostratigraphic record for the Altonian and Farmdalian Substages that documents warm-temperate upland oak-pine forest, prairie, and bottomland forest. At 23,000 yr B.P., white spruce and larch migrated into the Nonconnah Creek watershed and along braided-stream surfaces in the Mississippi Valley as far as southeastern Louisiana. The pollen and plant-macrofossil record from Nonconnah Creek provides the first documentation of a full-glacial locality in eastern North America for beech, yellow poplar, oak, history, black walnut, and other mesic deciduous forest taxa. During the full and late glacial, the Mississippi Valley was a barrier to the migration of pine species, while the adjacent Blufflands provided a refuge for mesic deciduous forest taxa. Regional climatic amelioration, beginning about 16,500 yr B.P., is reflected by increases in pollen percentages of cooltemperate deciduous trees at Nonconnah Creek. The demise of spruce and jack pine occurred 12,500 yr B.P. between 34° and 37° N in eastern North America in response to postglacial warming.


2007 ◽  
Vol 67 (3) ◽  
pp. 502-508 ◽  
Author(s):  
Matts Lindbladh ◽  
W. Wyatt Oswald ◽  
David R. Foster ◽  
Edward K. Faison ◽  
Juzhi Hou ◽  
...  

AbstractPicea is an important taxon in late-glacial pollen records from eastern North America, but little is known about which species of Picea were present. We apply a recently developed palynological method for discriminating the three Picea species in eastern North America to three records from New England. Picea glauca was dominant at ∼ 14,500–14,000 cal yr BP, followed by a transition to Picea mariana between ∼ 14,000 and 13,500 cal yr BP. Comparison of the pollen data with hydrogen isotope data shows clearly that this transition began before the beginning of the Younger Dryas Chronozone. The ecological changes of the late-glacial interval were not a simple oscillation in the position of a single species' range, but rather major changes in vegetation structure and composition occurring during an interval of variations in several environmental factors, including climate, edaphic conditions, and atmospheric CO2 levels.


1982 ◽  
Vol 60 (8) ◽  
pp. 1352-1356 ◽  
Author(s):  
Barry G. Warner

A leafy twig fragment of Thuja occidentalis L. was isolated from sediments dating about 10 000 years before present (B.P.) from Manitoulin Island, Ont. This is the earliest known record of Thuja leaves in postglacial deposits in eastern North America. Thuja may have arrived in Ontario in association with boreal spruce forests, but was a component of early pine forests.


1996 ◽  
Vol 45 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Jim I. Mead ◽  
Frederick Grady

AbstractPikas (Ochtona)—small gnawing mammals, related to rabbits—range today throughout parts of the Northern Hemisphere, but had a wider distribution during the Pleistocene. Nine caves from northeastern North America (a region not occupied by pikas today) have Pleistocene deposits containing remains of Ochotona. We examine 526 fossil specimens (ranging in age from approximately 850,000 to 8670 yr B.P.) from five of these caves. Two morphological forms of Ochotona lived in northeastern North America during the late Pleistocene—a large species (probably O. whartoni) and a small species (probably O. princeps).Ochotona of glacial age are not necessarily indicative of talus slopes and mesic communities. O. princeps-like of the Irvingtonian of West Virginia were living with an amphibian-reptilian assemblage found in the area today, implying winters not much, if at all, colder than at present. Late glacial and postglacial change in climate south of the ice sheets in effect would have isolated Ochotona in eastern North America, where they were unable to retreat to the west or north. Whereas western pika had the option of moving up in elevation, into boreal islands, eastern forms became restricted to ever-diminishing habitats, culminating in extinction and extirpation. Radiocarbon ages imply that Ochotona lived in eastern North America during the late Pleistocene (late Rancholabrean) and into the earliest Holocene. We describe the youngest remains of Ochotona in eastern North America and the youngest for the extinct large form, O. whartoni.


2015 ◽  
Vol 80 (1) ◽  
pp. 134-145 ◽  
Author(s):  
Matthew T. Boulanger ◽  
Metin I. Eren

AbstractRecently, advocates of an “older -than- Clovis” occupation of eastern North America have suggested that bi-pointed leaf-shaped lanceolate stone bifaces provide definitive evidence of human culture on the eastern seaboard prior to the Late Glacial Maximum. This argument hinges on two suppositions : first, that points of this form are exceedingly rare in the East and second, that all known occurrences of these point forms are from landforms or depositionaI environments dating to some time before the late Pleistocene. Neither of these suppositions is supported by the archaeological record. Bi-pointed leaf shaped blades have been recoveredfrom throughout the Middle Atlantic and Northeast, where they have been repeatedly dated, either radiometrically or by association with diagnostic artifacts, to between the Late Archaic and the Early Woodland. Statistical analysis of supposed “older-than-Clovis” leaf-shaped blades demonstrates that there are no significant differences in morphology between them and unequivocally Middle Holocene leaf-shaped blades. Until such time as evidence demonstrates otherwise, there is no reason to accept that these leaf-shaped bifaces are diagnostic of a Pleistocene, much less pre-Late Glacial Maximum, occupation in eastern North America.


1968 ◽  
Vol 33 (4) ◽  
pp. 441-445 ◽  
Author(s):  
James E. Fitting

AbstractIn definitions of the postglacial readaptation in eastern North America, attempts have been made to apply a single standard to the entire area. Such definitions are inadequate since a number of environmental zones existed in the region during late glacial and early postglacial times. These consisted of a periglacial zone with a fairly high carrying capacity supporting a cold-climate hunting adaptation; a zone of closed boreal forest with a relatively low carrying capacity; and a region of broadleaf and southern forests with a relatively high carrying capacity for a mixed gathering-and-hunting base. In the southeast there is a gradual transition from formally defined Paleo-Indian to Archaic culture, although both groups, if separation is possible, had potentially the same subsistence base. In the northeast there is a low population density hiatus between two periods of higher population density.


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