HR: 14:25h
AN: GC33B-04    [Abstracts]
TI: Twentieth Century Bristlecone Pine Tree Rings Near Upper Tree Limit Wider Than in Recent Millennia
AU: * Hughes, M K
EM: mhughes@ltrr.arizona.edu
AF: Laboratory of Tree-Ring Research, W Stadium 105 The University of Arizona, Tucson, AZ 85721, United States
AU: Salzer, M W
EM: msalzer@ltrr.arizona.edu
AF: Laboratory of Tree-Ring Research, W Stadium 105 The University of Arizona, Tucson, AZ 85721, United States
AB: Unusually wide tree-rings have been observed in recent decades in bristlecone pines from widespread locations at high elevations (3100 m.a.s.l. and above) near the upper forest border in the western USA. We present an enhanced and extended dataset from such environments, and report only results based on unmodified raw ring widths. These wide rings are unique in the context of at least the last 3700 years. Sites at similar elevations, but further below the upper tree limit, do not show this increase. The implications of these observations for possible explanations of the growth increase will be discussed, in the context of environmental changes unique to recent times. These will include the possible effects of increasing atmospheric concentrations of carbon dioxide on the trees' water use efficiency, enhanced nutrient availability related to pollution, shifts in seasonal climatic patterns, and mountain climate conditions unique to the 20th and 21st centuries. Particular attention will be given to this last explanation, and in particular to the possibility of uniquely "Anthropocene" patterns of vertical change and their consequences for tree growth.
DE: 1620 Climate dynamics (0429, 3309)
DE: 1851 Plant ecology (0476)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting