Pollen evidence for a mid-Holocene East Asian summer monsoon maximum in northern China
Pollen evidence for a mid-Holocene East Asian summer monsoon maximum in northern China
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DOI：
10.1016/j.quascirev.2017.10.008
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发表时间：
2017-11
影响因子：
4
通讯作者：
Ruilin Wen;Jule Xiao;Jiawei Fan;Shengrui Zhang;H. Yamagata
中科院分区：
文献类型：
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作者：
Ruilin Wen;Jule Xiao;Jiawei Fan;Shengrui Zhang;H. Yamagata
东亚夏季风增强带来的强降水究竟发生在全新世早期还是全新世中期，特别是在季风边缘地区，一直存在争议。关于这个问题的相互矛盾的观点可能是由于在不同沉积层序中测量的不同气候代用物在解释时的不确定性和模糊性造成的。本文基于位于现代夏季风极限附近的大理湖的高分辨率花粉记录，详细记录了中国北方全新世植被的演化。从12000 - 8300 cal BP，沙地景观由沙漠变为开阔的榆树林和灌丛，干燥草原占主导地位的丘陵和白桦林的斑块在山区发展。8300 ~ 6000 cal BP之间，榆树林广泛分布于沙地，典型草原覆盖于丘陵，针叶林与阔叶林混交林在山地扩张。我们的花粉证据与全新世早期季风降水增加的观点相矛盾；相反，这表明东亚夏季风直到中国北部约8000 cal BP才开始增强。全新世早期的低降水可归因于北半球高纬度冰盖的残余和全球海平面相对较低的边界条件。
There is a controversy regarding whether the high precipitation delivered by an intensified East Asian summer monsoon occurred during the early Holocene, or during the middle Holocene, especially in the context of the monsoonal margin region. The conflicting views on the subject may be caused by chronological uncertainties and ambiguities in the interpretation of different climate proxies measured in different sedimentary sequences. Here, we present a detailed record of the Holocene evolution of vegetation in northern China based on a high-resolution pollen record from Dali Lake, located near the modern summer monsoon limit. From 12,000–8300 cal BP, the sandy land landscape changed from desert to open elm forest and shrubland, while dry steppe dominated the hilly lands and patches of birch forest developed in the mountains. Between 8300 and 6000 cal BP, elm forest was extensively distributed in the sandy lands, while typical steppe covered the hilly lands and mixed coniferous–broadleaved forests expanded in the mountains. Our pollen evidence contradicts the view that the monsoonal rainfall increased during the early Holocene; rather, it indicates that the East Asian summer monsoon did not become intensified until ∼8000 cal BP in northern China. The low precipitation during the early Holocene can be attributed to the boundary conditions, i.e., to the remnant high-latitude Northern Hemisphere ice sheets and the relatively low global sea level.