HR: 0830h
AN: C21B-0817    [PDF]
TI: Holocene Landscape Change on the Arctic Coastal Plain of Alaska: Paleoecological Evidence From Deep Organic Deposits of Erosional Landscape Remnants
AU: * Eisner, W R
EM: wendy.eisner@uc.edu
AF: University of Cincinnati, Department of Geography, Cincinnati, 0H 45221-0131 United States
AU: Bockheim, J G
EM: bockheim@facstaff.wisc.edu
AF: University of Wisconsin, Department of Soil Sciences, Madison, WI 53706-1299 United States
AU: Hinkel, K M
EM: kenneth.hinkel@uc.edu
AF: University of Cincinnati, Department of Geography, Cincinnati, 0H 45221-0131 United States
AU: Peterson, K M
EM: afkmp@uaa.alaska.edu
AF: University of Alaska Anchorage, Department of Biological Sciences, Anchorage, AK 99508 United States
AU: Nelson, F E
EM: fnelson@udel.edu
AF: University of Delaware, Department of Geography, Newark, DE 19716 United States
AU: Jones, B M
EM: jonebm@email.uc.edu
AF: University of Cincinnati, Department of Geography, Cincinnati, 0H 45221-0131 United States
AB: The dominant landscape process on the Arctic Coastal Plain of northern Alaska is the formation and drainage of thaw lakes, a process which apparently began during the early Holocene more than 10,000 years ago. The continual formation and drainage of thaw lakes accounts for approximately 75% of the modern surface expression of the Barrow Peninsula. The processes associated with the thaw lake cycle usually obliterate lacustrine or peat sediments which could otherwise be used for paleoecological reconstruction. Long-term landscape and vegetation changes are therefore imperfectly understood, despite years of intensive study. We have identified several possible erosional remnants of a former peneplain surface that predate the formation of the thaw lakes. These remnants are characterized by higher elevations, a deep organic layer with very high ice content in the upper permafrost, and a plant community somewhat atypical of the region. A sediment core was extracted from one of these sites, sectioned, and sampled for pollen, soil organic carbon, and 14C dating. The lowest level of the organic sediments represents the earliest phase of plant growth, dating to about 9.3 ka calendar years. Palynological analysis and high carbon accumulation rates during this period indicate wet and possibly warmer conditions. This is interpreted as the local response to ameliorating climate during the Holocene thermal maximum (HTM) - the interval of warmth associated with peak Holocene temperature. Coupled with results from other sites in northern Alaska, a pattern is emerging of the early Holocene characterized by mesic shrub tundra (including sedge, birch, willow, and heath vegetation) associated with high carbon accumulation rates; these rates slow after ~8 ka, and slow even more after 4.5 ka, with a net carbon loss after 3 ka.
DE: 1620 Climate dynamics (3309)
DE: 1890 Wetlands
DE: 3322 Land/atmosphere interactions
DE: 3344 Paleoclimatology
DE: 9315 Arctic region
SC: Cryosphere [C]
MN: 2003 Fall Meeting