Climatic and palaeoecological changes during the mid- to Late Holocene transition in eastern China: high-resolution pollen and non-pollen palynomorph analysis at Pingwang, Yangtze coastal lowlands
Climatic and palaeoecological changes during the mid- to Late Holocene transition in eastern China: high-resolution pollen and non-pollen palynomorph analysis at Pingwang, Yangtze coastal lowlands
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DOI：
10.1016/j.quascirev.2014.06.013
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发表时间：
2014-09-01
影响因子：
4
通讯作者：
Chen, Zhongyuan
中科院分区：
文献类型：
--
作者：
Innes, James B.;Zong, Yongqiang;Chen, Zhongyuan
向全新世晚期/新冰期的过渡是一个世界性的气候恶化过程，从全新世中期的最佳热条件开始，在大约4200年前的急剧下降中达到顶峰，当时气候严重恶化，持续了两三个世纪。这一突如其来的气候事件被记录在世界各地的许多代理数据档案中，其影响根据区域天气系统和条件的反应以不同的方式表现出来，但干旱和/或寒冷温度往往大大增加。它被认为是当时几个久负盛名的人类社会突然崩溃的原因或促成了这些社会的崩溃，包括东部中国先进的新石器时代晚期农业文化。我们使用了高分辨率的花粉和非花粉孢粉形态分析，通过它对平旺植被和水文的影响来研究这种气候过渡的性质。平旺位于长江沿岸低地，没有证据表明海平面上升或重大的人类土地利用活动等复杂的环境影响，这些因素以前被认为是森林组成变化的替代原因。结果表明，森林变化有两个阶段，一个是从5500卡BP开始逐渐变化，另一个是在4200卡BP左右突然变化，亚热带森林成分的出现频率下降，取而代之的是针叶树和耐寒乔木。乔木的总花粉频率没有下降，温带森林树木的比例始终保持不变，这两个因素都排除了人类土地开垦是森林组成变化的原因。由于这些数据与从该地区其他代理档案建立的气候恶化的已知时间非常吻合，我们得出结论，气候是全新世中晚期中国东部植被变化的主要驱动因素。我们的水文结果支持这样的观点，即4200卡BP事件期间当地水位上升和气候降温的共同作用可能是长江下游社会崩溃的原因。(C)2014爱思唯尔有限公司。保留所有权利。
The transition to the Late Holocene/Neoglacial occurred as a worldwide process of climatic deterioration from the optimum thermal conditions of the mid-Holocene, culminating in an abrupt decline around 4200 cal yr ago, in a period of severe climatic deterioration that lasted for two or three centuries. This sudden climatic event has been recorded in many proxy data archives from around the world, and its effects were manifest in different ways depending on the reaction of regional weather systems and conditions, but often as greatly increased aridity and/or cold temperatures. It has been regarded as causing or contributing to the sudden collapse of several well-established human societies at that time, including advanced agricultural Late Neolithic cultures in eastern China. We have used high-resolution pollen and non-pollen palynomorph analysis to examine the nature of this climatic transition through its impacts on the vegetation and hydrology at Pingwang, a site in the Yangtze coastal lowlands which has no evidence of complicating environmental influences such as sea-level rise or significant human land-use activity, factors previously suggested as alternative reasons for changes in forest composition. Our results show two phases of forest alteration, one gradual from about 5500 cal BP and one sudden at about 4200 cal BP., in which the frequencies of subtropical forest elements fall and are replaced by those of conifers and cold-tolerant trees. Total arboreal pollen frequencies do not decline and the proportion of temperate forest trees, tolerant of a wide range of temperatures, remains unchanged throughout, both ruling out human land clearance as a cause of the change in forest composition. As these dates accord very well with the known timings of climate deterioration established from other proxy archives in the region, we conclude that climate was the main driver of vegetation change in eastern China at the mid-to Late Holocene transition. Our hydrological results support the view that a combination of rising local water level and climatic cooling during the 4200 cal BP event was the probable cause of societal collapse in the lower Yangtze valley. (C) 2014 Elsevier Ltd. All rights reserved.