HR: 0800h
AN: B51D-0248    [Abstracts]
TI: Mid-Continent Expressions of Oceanic Teleconnections Evidenced in Red Pine Tree Rings
AU: * Kaplan, S W
EM: swkaplan@wisc.edu
AF: University of Wisconsin - Madison, Center for Climatic Research, 1225 West Dayton Street, Madison, WI 53706 United States
AU: Wilkins, D E
EM: dwilkins@boisestate.edu
AF: Boise State University, Department of Geosciences, 1910 University Drive , Boise, ID 83725 United States
AU: Grissino-Mayer, H D
EM: grissino@utk.edu
AF: University of Tennessee, Department of Geography, 1000 Phillip Fulmer Way, Knoxville, TN 37996 United States
AU: van de Gevel, S
EM: saskia@utk.edu
AF: University of Tennessee, Department of Geography, 1000 Phillip Fulmer Way, Knoxville, TN 37996 United States
AU: Weinert, M
EM: wien0007@umn.edu
AF: University of Minnesota, Department of Geography, 267 19th Avenue South, Minneapolis, MN 55455 United States
AB: Two stands of Red Pine ( Pinus resinosa) from Itasca State Park in northcentral Minnesota, U.S.A. were studied as part of the 2004 North American Dendroecological Fieldweek. The goal of the workshop was to evaluate the sensitivity of Pinus resinosa at its western limit to local and regional records of temperature and precipitation as well as fill a gap in the geographic network of tree-ring-climate reconstructions in the interior of North America. An unexpected finding of the research was a strong relationship between radial growth in the trees and the North Atlantic Oscillation and the Niño 3.4 indices, patterns not previously described in tree rings from the western Great Lakes region. Duplicate cores from over thirty trees were measured and crossdated to produce a stand chronology spanning 280 years (1724-2003) with an interseries correlation of 0.52 and a mean sensitivity of 0.23 based on COFECHA output. Raw measurements were standardized using a negative exponential curve to remove growth trends. Biological response functions developed with PRECON reveal that 40% of the variance in the residual chronology is explained by temperature and to a lesser degree precipitation, with warm springs (February-May) and cool summers (July) having the strongest influence on tree growth. Correlations with local station and divisional climate records support the analysis with Pinus resinosa responding most positively to warm February temperatures and cool July temperatures. Warm February-May temperatures reduce the snowpack and make moisture available to the trees in the early growing season while cool July conditions limit evaporation, again increasing moisture availability. Correlation of the Minnesota Pinus resinosa ring-width indices with values of oceanic teleconnections reveal a small but significant (r² = ~16%, p < 0.05) influence of modes of the NAO and Niño 3.4 on tree ring growth in the upper Midwest. There is an inverse relationship between February NAO and ringwidth and a positive correlation between the Niño 3.4 index in July and August of the previous growing season and radial growth in the current year. The inverse relationship between February NAO and ringwidth is interesting as a positive NAO is generally associated with warmer and wetter winter conditions in the eastern U.S. The position of Itasca State Park may be just north and west of a hinge line between the dominance of cold dry arctic air that persists over central Canada during positive phases of the NAO and the front of warm wet air advecting off of the Atlantic High and into the eastern and central U.S.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0424 Biosignatures and proxies
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
SC: Biogeosciences [B]
MN: Fall Meeting 2005