| Detecting changes in ENSO frequency through the last glacial period |
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We are using both glacial and modern wood samples to identify El Niño Southern Oscillation (ENSO) events throughout the life history of individual trees, and by doing so, increase our understanding of the climate-biotic relationship which has likely changed between these time periods. This study addresses both the causes and responses to climate variability by comparing locations (S. California and New Zealand) and time periods (glacial ~40 KYA, and modern) that have starkly contrasting climates and developmental histories. Using the a-cellulose from individual tree rings, we can measure the stable isotopic signature of d18O to detect the occurrence of ENSO events as recorded in tree-rings. Changes in a-cellulose d18O reflect environmental changes in the source-water (including timing of rainfall) and humidity experienced by the tree for both modern and glacial wood. |
| Juniper samples recovered from the La Brea tar pits, Page Museum, LA |
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Our paleo tree samples originate from two locations. Our Juniperus samples come from the Rancho La Brea Tarpits at the Page Museum of Natural History. Our southern hemisphere samples come from the North Island of New Zealand. The Kauri wood was graciously provided to us by Ancientwood, Ltd. Ancient specimens from both locations are highly preserved in their original organic state, providing us with the opportunity to conduct high-resolution tree-ring analyses and stable isotope measurements. This project permits us to conduct powerful quantitative coupling between ENSO detection (with d18O), growth analysis (tree ring width), and physiological functioning (with d13C) within a given tree ring. |
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