A 26-year stable isotope record of humidity and El Nino-enhanced precipitation in the spines of saguaro cactus, Carnegiea gigantea

English, Nathan B., Dettman, David L., and Williams, David G. (2010) A 26-year stable isotope record of humidity and El Nino-enhanced precipitation in the spines of saguaro cactus, Carnegiea gigantea. Palaeogeography, Palaeoclimatology, Palaeoecology, 293 (1-2). pp. 108-119.

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Seasonal and annual variations of rainfall and humidity are recorded in the carbon and oxygen stable isotope ratios of sequentially grown spines found on the columnar cactus, Carnegiea gigantea. A 26-year long composite δ^18 O and δ^13 C isotope record from the spines of five saguaro cacti was created using bomb radiocarbon and semi-annual variations in δ^13 C. Once dating errors in the composite record are corrected, mean annual spine δ^18 O is negatively correlated (P<0.001) with total annual precipitation (TAP) from November through October and positively correlated (P<0.01) with mean annual nighttime vapor pressure deficit (VPD). Year-to-year decreases (>2 parts per thousand) in the maximum annual spine δ^18 O are positively correlated (P<0.01) with the Southern Oscillation Index (SOI). We attribute these decreases to enhanced winter rainfall associated with the El Nino phase of the El Nino-Southern Oscillation. Minimum annual δ^13 C is negatively correlated with TAP (P<0.05) and mean nighttime VPD (P<0.05). These results bolster proposed mechanistic models of isotopic variation in the spines of columnar cactus and demonstrate how isotopic spine series may be used as climate proxies in regions of the Americas where trees suitable for traditional or isotopic dendrochonology are absent.

Item ID: 19191
Item Type: Article (Research - C1)
ISSN: 1872-616X
Keywords: stable isotopes; radiocarbon; dendrochronology; acanthochronology; terrestrial climate proxies; El Nino; cactus; Saguaro; Carnegiea gigantea
Date Deposited: 22 Dec 2011 00:04
FoR Codes: 04 EARTH SCIENCES > 0402 Geochemistry > 040203 Isotope Geochemistry @ 51%
04 EARTH SCIENCES > 0401 Atmospheric Sciences > 040104 Climate Change Processes @ 24%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050199 Ecological Applications not elsewhere classified @ 25%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960510 Ecosystem Assessment and Management of Sparseland, Permanent Grassland and Arid Zone Environments @ 50%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 50%
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