Climatic and anthropogenic influence on vegetation in southeastern China during the past 120 years inferred from speleothem
Climatic and anthropogenic influence on vegetation in southeastern China during the past 120 years inferred from speleothem
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DOI：
10.1016/j.quaint.2022.02.026
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发表时间：
2022-03
影响因子：
2.2
通讯作者：
Jiayu Lu;Haiwei Zhang;Hanying Li;Lijuan Sha;Rui Zhang;Jingyao Zhao;Youwei Li;Jian Wang;Xiyu Dong;R. Edwards;Z. Qian;Hai Cheng
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文献类型：
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作者：
Jiayu Lu;Haiwei Zhang;Hanying Li;Lijuan Sha;Rui Zhang;Jingyao Zhao;Youwei Li;Jian Wang;Xiyu Dong;R. Edwards;Z. Qian;Hai Cheng
洞穴群同位素记录已广泛应用于古气候研究的前沿。虽然洞穴群落的氧同位素(δ18O)记录仍然是最常用的水文气候指标，但洞穴群落的碳同位素(δ13C)和微量元素记录在刻画区域-局部水文气候变化方面也显示出独特的优势。本文介绍了中国东南部牛壁洞120年来的两个高分辨率(季节性-月度)和精确年代测定的洞穴δ13C记录(NB2和NB3)。我们的分析表明，水文气候引起的区域植被覆盖度的变化似乎是过去120年来洞穴δ13C值的主要控制因素。然而，在20世纪50年代末至60年代初，在Nb记录中观察到了一次较大的δ13C高漂移，这显然与中国近代史上的一次特殊的人类活动有关，即所谓的钢铁大跃进。根据δ-18O和微量元素数据推算的当地降水仍处于正常状态，我们认为这段时间内区域植被遭受的较大程度的破坏导致了观测到的较高的δ13C值。1980-2018年CE期间Nbδ13C记录的持续下降趋势可能归因于降水、温度和大气CO_2的增加所带来的植被效应的增加以及大气δ_(13)C的减少。
Speleothem isotope records have been widely used in the forefront of paleoclimate researches. Although the oxygen isotope (δ18O) records of speleothems remain the most commonly used hydroclimate proxy, the carbon isotope (δ13C) and trace element records of speleothem have also shown their unique advantages in charactering regional-local hydroclimate variations. In this study, we present two high-resolution (seasonal-monthly) and precisely dated speleothem δ13C records (NB2 and NB3) over the past 120 years from Niubi cave in Southeast China. Our analyses show that hydroclimate-induced changes in the regional vegetation coverage appear to be the primary control on the speleothem δ13C values over the past 120 years. However, during the late 1950s to early 1960s, a large high δ13C excursion is observed in the NB record, which is apparently linked to a special human activity in China's modern history, the so-called “Great Leap Forward in Iron and Steel”. We suggest that the large degree of damages to regional vegetation occurred during the time period resulted in the observed high speleothem δ13C values, as the local precipitation remained in an ordinary state inferred from δ18O and trace element data. The persistent decreasing trend in the NB δ13C record during the 1980–2018 CE may be attributed to the increased vegetation effect via increases in precipitation, temperature and atmosphere CO2, as well as the decrease of δ13C of atmospheric CO2.