HR: 17:30h
AN: PP14B-07    [Abstracts]
TI: Precipitation variability inferred from the annual growth and isotopic composition of tropical trees
AU: * Ballantyne, A P
EM: apb14@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708 United States
AU: Baker, P A
EM: pbaker@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708 United States
AU: Chambers, J Q
EM: jeffrey.chambers@tulane.edu
AF: Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118 United States
AU: Villalba, R
EM: ricardo@lab.cricyt.edu.ar
AF: Instituto Argentina de Nivologia, Glaciologia y Ciencias Ambientales, IANIGLA, Mendoza, CP(5500) Argentina
AB: Here we demonstrate that annual growth and isotopic ratios in tropical trees are responsive to seasonal and annual precipitation variability. We identify several regions of tropical South America characterized by significant relationships between oxygen isotopic ratios (δ ¹⁸O) in precipitation and precipitation amount (r = -0.82). Many of these regions are also sensitive to inter-annual variability in the South American Monsoon modulated by the El Niño Southern Oscillation (ENSO). The effectiveness of δ ¹⁸O and annual growth of tropical trees as a precipitation proxy is validated by high-resolution sampling of a Tachigali vermelho tree growing near Manaus, Brazil (3.1° S, 60.0° S). Growth in Tachigali spp. was highly correlated with both precipitation and cellulose δ ¹⁸O (r = 0.60) and precipitation amount was significantly correlated with δ ¹⁸O at a lag of approximately one month (r = 0.56). We also report a multi-proxy record spanning 180 years from Cedrela odorata growing in the Peruvian Amazon near Puerto Maldonado (12.6° S, 69.2° W) revealing a significant relationship between cellulose and monsoon precipitation over the region (r = -0.33). A 150-year record obtained from Polylepis tarapacana growing at Volcan Granada in Northern Argentina (22.0° S, 66.0° W) is also reported with a significant relationship between local monsoon precipitation and a regionally derived ring width index (r = 0.38). Although no significant relationship was revealed between cellulose δ ¹⁸O and precipitation in this taxa at this location, separate radii within the same tree revealed a significantly coherent δ ¹⁸O signal (r = 0.38). We compared our proxy chronologies with monsoon precipitation reanalysis data for tropical South America, which revealed key features of the South American Monsoon and their sensitivity to ENSO variability.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4920 Dendrochronology
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005