Peat humification records from Restionaceae bogs in northern New Zealand as potential indicators of Holocene precipitation, seasonality, and ENSO
Peat humification records from Restionaceae bogs in northern New Zealand as potential indicators of Holocene precipitation, seasonality, and ENSO
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DOI：
10.1016/j.quascirev.2019.06.036
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发表时间：
2019-08
影响因子：
4
通讯作者：
R. Newnham;Z. Hazell;D. Charman;D. Lowe;A. Rees;M. Amesbury;T. Roland;Maria J. Gehrels;V. Bos;I. Jara
中科院分区：
文献类型：
--
作者：
R. Newnham;Z. Hazell;D. Charman;D. Lowe;A. Rees;M. Amesbury;T. Roland;Maria J. Gehrels;V. Bos;I. Jara
与温度重建相比，新西兰关于古降水的替代记录很少，尽管降水在当代气候变率和预测的气候影响中很重要。在这项研究中，根据泥炭腐殖化分析，获得了新西兰北部两个不同水文营养的雷氏科沼泽的中晚全新世古水位变化记录。在每个地点，分析了三个岩心的泥炭腐殖化，促进了地点内和地点间的比较。利用放射性碳测年和年代学方法建立了六个序列的年龄模型。识别出12个tephers(包括6个加密tephra)，其中4个用于精确连接两个站点，并分别定义记录的起点和终点，分别为7027 ± 170(土华Tephra)和1718 ± 10 Cal yr BP(Taupo Tephra)(2个σ-年龄范围)。我们发现，在短期时间尺度上，六种泥炭腐殖化记录之间的个体差异可能是由于当地立地因素，特别是植被和微地形的变化，或者是所分析材料的组成的变化。在所有六个记录之间观察到了更强的长期一致性，但归因于随着时间的推移缓慢的厌氧衰减，因为隐含的在全新世晚期夏季更潮湿的趋势不能被独立的气候指标所证实。尽管有这些混杂的因素，沼泽表面湿度百年尺度的变化是所有六个记录的普遍特征，在时间上有不同程度的重叠，这表明与赤道东太平洋的厄尔尼诺-南方涛动重建有很强的对应关系。这些结果表明，新西兰营养丰富的沼泽地的泥炭腐殖化记录有可能解释过去的气候变化，也表明了从一个以上的地点开发多个测年良好的剖面的重要性。
In comparison with temperature reconstructions, New Zealand proxy records for paleo-precipitation are rare, despite the importance of precipitation in contemporary climate variability and for projected climate impacts. In this study, records of mid-late Holocene palaeomoisture variation were derived for two hydrologically separate ombrotrophic Restionaceae bogs in northern New Zealand, based on peat humification analysis. At each site, three cores were analysed for peat humification, facilitating both intra- and inter-site comparisons. Age models for the six sequences were developed using radiocarbon dating and tephrochronology. Twelve tephras (including six cryptotephras) were recognised, four of which were used to precisely link the two sites and to define start and end points for the records at 7027 ± 170 (Tuhua tephra) and 1718 ± 10 cal yr BP (Taupo tephra) (2σ-age ranges), respectively. We find individual differences between the six peat humification records at short-term timescales that are presumably due to local site factors, in particular changing vegetation and microtopography, or to changes in the composition of the material analysed. Stronger longer-term coherence is observed between all six records but is attributed to slow anaerobic decay over time because the implied trend towards wetter summers in the late Holocene cannot be corroborated by independent climate proxies. Despite these confounding factors, centennial scale shifts in bog surface wetness are a pervasive feature of all six records with varying degrees of overlap in time that show strong correspondence with El Niño-Southern Oscillation reconstructions from the eastern equatorial Pacific. These results indicate the potential for peat humification records from New Zealand's ombrotrophic bogs to elucidate past climate variability and also demonstrate the importance of developing multiple well-dated profiles from more than one site.