The northeastern Qinghai‐Tibet Plateau is strongly influenced by the East Asian summer monsoon (EASM), the Indian summer monsoon (ISM) and the westerlies. However, how these various circulation systems interacted in the region during the Holocene, and the nature of the associated environmental impacts, are unclear and even controversial. Here we present a high‐resolution pollen record from Caodalian Lake since 7.9 ka (1 ka = 1,000 cal yr BP), which is used to reconstruct the regional vegetation history and climatic changes. In addition, we use a novel procedure for pollen‐based quantitative paleoclimatic reconstruction to characterize the evolution of precipitation at Caodalian Lake and nearby Qinghai Lake. The results suggest that mean annual precipitation (P_ann) is the most significant factor controlling the fossil pollen record at both sites, and the P_ann reconstructions are well correlated with each other (r = 0.72, p < 0.001). A synthesis of the P_ann records from the two sites indicates that the precipitation in the region began to increase before 10 ka, reached a maximum during 10–5 ka, and gradually decreased thereafter. We propose that the pattern of precipitation evolution in the Qinghai Lake basin resulted from the combined effects of the ISM and EASM, with a precipitation maximum of 10–7 ka for the ISM and 7–5 ka for the EASM; both systems contributed to the regional precipitation maximum during 10–5 ka. Our well‐dated and unambiguous P_ann record also provides the opportunity to reconcile paleoenvironmental reconstructions derived from different paleoenvironmental proxies from the Qinghai Lake basin.

中文翻译：

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青藏高原东北部的植被历史和降水变化：曹达莲湖花粉记录达7900年

东北青藏高原受到东亚夏季风（EASM），印度夏季风（ISM）和西风的强烈影响。然而，这些全新的循环系统在全新世期间如何在该地区相互作用，以及相关环境影响的性质尚不清楚，甚至是有争议的。在这里，我们介绍了自7.9 ka（1 ka = 1,000 cal yr BP）以来高大莲湖的高分辨率花粉记录，该记录用于重建区域植被历史和气候变化。此外，我们使用一种基于花粉的定量古气候重建的新方法来表征高大连湖和附近青海湖的降水演变。结果表明平均年降水量（P _ann）是控制两个站点上化石花粉记录的最重要因素，并且P _ann重建彼此之间具有很好的相关性（r  = 0.72，p  <0.001）。来自这两个地点的P _ann记录的综合表明，该地区的降水在10 ka之前开始增加，在10-5 ka期间达到最大值，然后逐渐减少。我们认为，青海湖流域降水演变的模式是由ISM和EASM共同作用造成的，ISM的最大降水量为10-7 ka，而EASM的最大降水量为7-5 ka。这两个系统都导致了10-5 ka期间的区域最大降水量。我们的历史_{悠久，模棱两可} 记录还为调和来自青海湖流域不同古环境代理的古环境重建提供了机会。