HR: 0800h
AN: PP11A-1429    [Abstracts]
TI: Shifting Tree Growth-Climate Relationships in Subalpine Conifers of the Northern Rocky Mountains, U.S.A.
AU: * Kipfmueller, K F
EM: kurt@umn.edu
AF: Department of Geography, University of Minnesota, 414 Social Sciences Building 267-19th Avenue SOuth, Minneapolis, MN 55455 United States
AB: The relationship between temperature, precipitation, and radial tree growth were examined for whitebark pine (Pinus albicaulis Englem.) and subalpine larch (Larix lyallii Parl.) collected from three upper treeline sites in Idaho and Montana. Correlation analysis and response functions were used to compare seasonal temperature and precipitation with radial growth indices for three periods: the full instrumental record (1901-1998), an early period (1901-1949), and a late period (1950-1998). Over the full instrumental record the strongest relationship between the climate variables and growth occurred during the summer months, with strong positive associations occurring between growth and temperature and negative associations with precipitation. The correlation between radial growth and summer temperature was strongest during the early period of the record and weakened in both species during the late period. The weakening was more pronounced in whitebark pine than in subalpine larch. During the later period, spring temperature and precipitation were more strongly related to growth and may have reduced growth sensitivity to summer temperatures, representing a shift in limiting factors. This shift in sensitivity to climate may be due in part to decadal fluctuations in snowpack conditions in this region, perhaps modified by the phase of the Pacific Decadal Oscillation. An additional hypothesis of increasing growing season temperature during the late 20th century is also explored as a potential mechanism resulting in reduced sensitivity to climate during the later period
DE: 0429 Climate dynamics (1620)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005