δ18O in the Tropical Conifer Agathis robusta Records ENSO-Related Precipitation VariationsReportar como inadecuado




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Long-lived trees from tropical Australasia are a potential source of information about internal variability of the El Niño-Southern Oscillation ENSO, because they occur in a region where precipitation variability is closely associated with ENSO activity. We measured tree-ring width and oxygen isotopic composition O of -cellulose from Agathis robusta Queensland Kauri samples collected in the Atherton Tablelands, Queensland, Australia. Standard ring-width chronologies yielded low internal consistency due to the frequent presence of false ring-like anatomical features. However, in a detailed examination of the most recent 15 years of growth 1995–2010, we found significant correlation between O and local precipitation, the latter associated with ENSO activity. The results are consistent with process-based forward modeling of the oxygen isotopic composition of -cellulose. The O record also enabled us to confirm the presence of a false growth ring in one of the three samples in the composite record, and to determine that it occurred as a consequence of anomalously low rainfall in the middle of the 2004-5 rainy season. The combination of incremental growth and isotopic measures may be a powerful approach to development of long-term 150+ year ENSO reconstructions from the terrestrial tropics of Australasia.



Autor: Bjorn M. M. Boysen, Michael N. Evans , Patrick J. Baker

Fuente: http://plos.srce.hr/



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