Boysen Bjorn M M, Evans Michael N, Baker Patrick J
Department of Environmental and Primary Resources, State of Victoria, East Melbourne, Victoria, Australia.
Department of Geology and Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, United States of America.
PLoS One. 2014 Jul 25;9(7):e102336. doi: 10.1371/journal.pone.0102336. eCollection 2014.
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 (δ18O) of α-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 δ18O and local precipitation, the latter associated with ENSO activity. The results are consistent with process-based forward modeling of the oxygen isotopic composition of α-cellulose. The δ18O 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.
来自热带澳大拉西亚的长寿树木是了解厄尔尼诺-南方涛动（ENSO）内部变率的潜在信息来源，因为它们生长在一个降水变率与ENSO活动密切相关的地区。我们测量了从澳大利亚昆士兰州阿瑟顿高原采集的昆士兰贝壳杉样本中α-纤维素的年轮宽度和氧同位素组成（δ18O）。由于频繁出现类似假年轮的解剖特征，标准的年轮宽度年表内部一致性较低。然而，在对最近15年（1995 - 2010年）的生长情况进行详细检查时，我们发现δ18O与当地降水之间存在显著相关性，而当地降水与ENSO活动有关。这些结果与基于过程的α-纤维素氧同位素组成正向模型一致。δ18O记录还使我们能够确认复合记录中三个样本之一存在一个假生长轮，并确定它是2004/5雨季中期降雨异常少的结果。增量生长和同位素测量相结合可能是从澳大拉西亚陆地热带地区开发长期（150多年）ENSO重建的有力方法。
