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Northeast China played an irreplaceable role in population migrations and cultural exchanges in East Asia during the Paleolithic. This paper collected 182 archaeological sites to analyse the characteristics of spatial-temporal variations of Paleolithic human activities in Northeast China, and explored the driving mechanisms behind these variations in combination with the paleoenvironmental and archaeological studies. During the Lower Paleolithic, constrained by the relatively cold-dry climate and blocked by the Songnen paleo-lake basin, the population was sparse and distributed only near 40° N at the southern end of Northeast China. Upon entering the Middle Paleolithic, as humans developed greater tolerance to cold climates and adopted more sophisticated survival strategies with the application of small lithic tools, their numbers increased and geographical distribution expanded northward to 45° N at the central region of Northeast China. The Upper Paleolithic saw a considerable increase in population and expansion across almost all of Northeast China except for the eastern Inner Mongolia Plateau. We speculated that 50 ka and 30 ka BP were two key points, both of which may be associated with a significant increase in the frequency of migrations and communications among humans, and the widespread popularity of highly mobile microblade technology, respectively. In addition, the environmental analysis of archaeological sites revealed a continuous spread of Paleolithic humans to areas with higher elevations, steeper slopes, and lower temperatures. Meanwhile, they were becoming less reliant on water resources and were more widely conducting activities in open-air areas, showing that the environmental adaptability had been continuously improving over time. This study can provide a reference for the reconstruction of the migration history of early humans in East Asia, and is also of great significance for a comprehensive understanding of the evolutionary process of early human-environment interactions. [ABSTRACT FROM AUTHOR]

The northern edge of the East Asian monsoon region is also a transition zone of temperate continental and monsoon climate, which is a sensitive zone of global climate and ecological environment change. It is an urgent problem to find out the long-term climate change rules of this region. Using 101 tree core samples obtained from 54 trees, a 343-year tree-ring width chronology of the Platycladus orientalis (L.) Franco (1673–2016) in the Wula Mountains, Inner Mongolia, China was established. The analysis shows that the radial growth of P. orientalis is closely related to hydrothermal conditions, the average minimum temperature and relative humidity are the main factors that determine the growth of P. orientalis. Based on the strong correlation between the tree-ring indices and the annual average minimum temperature (r = −0.870, p < 0.001), we reconstructed an average annual minimum temperature series from 1673 to 2016 using a linear regression equation, and the reconstructed equation can explain 75.724% of the variance, respectively. According to the data from the past 343 years, the changes in the annual average minimum temperature series had the cycles of 58.6-, 7.7-, 3.4-, 3.1-, 2.2-, and 2.1-years; the series showed three warm periods (1824–1830, 1909–1922, and 1986–2011) and 4 cold periods (1703–1712, 1731–1738, 1754–1763, and 1937–1951). The low temperature periods recorded in the reconstructed series for the 17th and 18th centuries are consistent with the Little Ice Age that occurred in the northern hemisphere, and the heating rate significantly increased at the end of the 20th century. In addition, the cold and warm periods recorded by the reconstruction result is basically consistent with the extreme climate events recorded in the historical documents of the region and the reconstruction results in other regions. In this paper, the world's first chronology of P. orientalis tree ring width was established. A historical sequence of annual average minimum temperature of 343 years was reconstructed in a typical region of the East Asian monsoon climate. It fills in the blank of reconstruction sequence and variation characteristics of mean minimum temperature in the northern edge of East Asian monsoon and transition zone of temperate continental and monsoon climate in recent four centuries. [ABSTRACT FROM AUTHOR]

Abstract There are ten ephemeral tributaries of the Yellow River in the Inner Mongolia of China. As their catchments are covered by loose materials and are dominated by an intense interaction between wind and water erosion, these tributaries have had a high sediment yield and alluvial fans have been formed at the confluences of the tributaries with the Yellow River. However, there is a lack of understanding in the deposition model of the alluvial fans and the roles of fluvial and aeolian processes in sediment accumulation. In this paper, we used Ground Penetrating Radar (100 MHz) and sediment cores to investigate the sediments in channels and alluvial fans of four out of the ten tributaries. Radar reflection profiles of sedimentary strata are dominated by horizontal or sub-horizontal layers with a large scale, showing that the fluvial deposition on the alluvial fans has been dominated by a vertical accretion pattern. The reflection features like reflection free, inclined reflections, discontinuous, undulate, chaotic, sinuous reflections and channel fill exist to a lesser extent. A few GPR profiles send signs of intense erosion, and the one near the apex of an alluvial fan reveals that erosion had been active likely during the early Holocene and the channel position should be relatively fixed. The information extracted from this profile and the widely exposed late Pleistocene strata in the upper parts of the alluvial fans according to the geological map of the study area indicates that sediment accumulation has been slow in the upper alluvial fans since the early Holocene. The sediment cores indicate that sedimentary strata under the alluvial fans are mainly composed by sand and silt deposited in a fluvial environment and rarely reworked by wind actions. Also according to the core data, the sediment deposits in the west fans were coarser than those in the east fans, likely suggesting that the hydrodynamic force of the western tributaries was stronger than that of the east ones. The hydrodynamic environment of the tributaries was usually unstable historically and hyperconcentrated flows might occur with a higher frequency in one of the tributaries in history. [ABSTRACT FROM AUTHOR]

Studies of the East Asian Neolithic have been conducted for more than a century and many attempts have been made to interpret the functions of prehistoric pottery, particularly the earliest ceramics. The unsophisticated pottery discovered in the Weijiawopu site opens a window for the study of early ceramic function. We conducted plant residue analyses of ceramics from the Weijiawopu Neolithic site; the largest Hongshan Culture settlement in Inner Mongolia, China. The site is thought to belong to the early to middle period of the Hongshan Culture, approximately 6500-5500 cal BP. Based on evidence from starch grains, we identified four main plant resources: 1) cereal grains; 2) Dioscorea plant tubers; 3) beans; and 4) nuts. None of the individual starch grains exhibit surface damage, indicating they did not undergo extensive processing such as grinding or cooking. Hence, we conclude that the pottery samples analyzed derive from food storage containers, indicating one major function of early pottery at the site. Furthermore, wild plants are thought to have been an essential part of the Weijiawopu people's subsistence base, suggesting a mixed economic pattern based upon both domestication activities and hunting-gathering-foraging lifeways. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a spatially and temporally improved reconstruction of mean summer (June–August) temperature derived from tree-ring width data of Dahurian larch (Larix gmelinii Rupr.) from the northern Great Xing''an Mountains, Northeast China. Three new chronologies were added to the original 2011 reconstruction, and the reconstruction extended back to AD 1715. The reconstruction was generated using a simple linear regression method, verified by independent meteorological data, and accounts for 47.0% of the actual temperature variance during the common period (1957–2008). The reconstruction captures decadal and century-scale regional temperature variability, such as cold decades (1940s, 1930s, 1790s, 1950s and 1850s), warm decades (2000s, 1870s, 1750s, 1980s and 1840s), a cold half-century (ca. 1750–1799), and a warm half-century (ca. 1900–1949). It also reveals slightly higher frequency of cold years (20.4%) than warm years (18.0%), and a recent warming trend. Compared to the original 2011 reconstruction, this reconstruction has lower inter-annual temperature variability, high explained variance and high representativeness of regional climate. The reconstruction also correlates with the East Asian Monsoon and the Pacific Ocean signals, and indicates the feasibility of using tree rings from high latitude Northeast China to reconstruct summer temperature in permafrost forest environments. [Copyright &y& Elsevier]