Journal of Oceanology and Limnology https://doi.org/10.1007/s00343-019-7243-9 Vegetation and climate history of Anggertu Lake in the Tengger Desert over the last millennium* DUAN Futao (段阜涛), AN Chengbang (安成邦) ** , ZHAO Yongtao (赵永涛), WANG Wei (王伟), CAO Zhihong (曹志宏), ZHOU Aifeng (周爱峰) College of Earth Environmental Sciences, MOE Key Laboratory of Western China’s Environmental Systems, Lanzhou University, Lanzhou 730000, China Received Aug. 22, 2017; accepted in principle Oct. 26, 2017; accepted for publication Dec. 26, 2017 © Chinese Society for Oceanology and Limnology, Science Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Reconstructing climate change of the last millennium is important to understand the current relationship between human-social activities and natural environmental changes. Pollen assemblages, loss-on-ignition (LOI org at 550°C), and grain size data collected from sediment core AGE15A from the center of Anggertu lake (eastern Tengger Desert, Inner Mongolia) were used to reconstruct the regional vegetation and climate history of the last millennium. Desert or steppe desert, dominated by Artemisia and Amaranthaceae, expanded around this region during the period of 988–1437 AD indicating a generally dry climate condition with two short humid periods (1003–1082 AD and 1388–1437 AD). These two wet periods were characterized by relatively high vegetation cover and bioproductivity, as reflected by high pollen concentrations and LOI org values. Increases in steppe and meadow vegetation communities (Poaceae, Cyperaceae) and vegetation cover during 1437–2015 AD suggest a wetting trend, which was also deduced from a gradual trend towards fine grains and higher lake biological productivity as reflected by LOI org values. An unstable lacustrine environment was identified via frequent fluctuations in pollen concentration and grain size after 1842 AD. This study also recorded a relatively dry Medieval Warm Period (MWP, 1082– 1388 AD) and a wet Little Ice Age (LIA, 1437–1842 AD). Increased Amaranthaceae and high abundance of Poaceae may be related to overgrazing and agricultural activities that took place during those time periods. The evolution of vegetation in the lake region was influenced by climate change and human activities. These results could provide more fundamental support for studies of the environmental evolution of the Tengger Desert. Keyword: Anggertu Lake; Tengger Desert; lacustrine record; vegetation; climate changes; the last millennium 1 INTRODUCTION Studying the last millennium of climate change can help us to understand the current relationship between human-social activities and natural environmental changes. In particular, the Medieval Warm Period (MWP) and Little Ice Age (LIA) are abrupt climatic events with global signatures during the last millennium (Mann et al., 2009). There are distinct temperature discrepancies between these two intervals (PAGES 2k Consortium, 2013), and they significantly influenced on human civilization and dynastic changes over the last millennium (Zhang et al., 2008a; Kennett et al., 2012). However, moisture conditions at various locations during these two climatic events remain controversial and require further study. Numerous recent studies have reconstructed the climate changes of the last millennium in different regions in China based on multi-proxy (e.g., tree-rings, ice cores, lake sediments, and historical documents) approaches. For example, reconstruction of climate changes on the northeastern Tibetan Plateau from various types of paleoclimatic archives (Yao et al., 1991; Mosley- Thompson et al., 1993; Zhang et al., 2004b; Yang et * Supported by the National Natural Science Foundation of China (No. 41372180) ** Corresponding author: cban@lzu.edu.cn