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Aeolian processes have been studied extensively at low elevations, but have been relatively little studied at high elevations. Aeolian sediments are widely distributed in the Yarlung Zangbo River basin, southern Tibetan Plateau, which is characterized by low pressure and low temperature. Here, we comprehensively analyzed the wind regime using data since 1980 from 11 meteorological stations in the study area, and examined the interaction between the near-surface wind and aeolian environment. The wind environment exhibited significant spatial and temporal variation, and mean wind speed has generally decreased on both annual and seasonal bases since 1980, at an average of 0.181 m/(s·10a). This decrease resulted from the reduced contribution of maximum wind speed, and depended strongly on variations of the frequency of sand-driving winds. The drift potential and related parameters also showed obvious spatial and temporal variation, with similar driving forces for the wind environment. The strength of the wind regime affected the formation and development of the aeolian geomorphological pattern, but with variation caused by local topography and sediment sources. The drift potential and resultant drift direction were two key parameters, as they quantify the dynamic conditions and depositional orientation of the aeolian sediments. Wind affected the spatial variation in sediment grain size, but the source material and complex topographic effects on the near-surface wind were the underlying causes for the grain size distribution of aeolian sands. These results will support efforts to control aeolian desertification in the basin and improve our understanding of aeolian processes in high-elevation environments.

The Holocene Climate Optimum (HCO) was an important interval in the development of human civilization and has been the focus of many paleoclimatic studies. However, there are significant regional differences in the timing of the HCO due to the complex response of regional climates to insolation changes, associated with internal feedbacks within the climate system. Here, we present the results of a study of magnetic and geochemical properties of loess-paleosol sequences from across mid-latitude Asia, with the aim of assessing differences in the timing of the HCO. The HCO generally occurred after ~5 ka in Tajikistan and Xinjiang; during 5–2.5 ka in the western Chinese Loess Plateau (CLP); and during ~8–2.5 ka in the central CLP. This asynchroneity reflects differences in the response of regional climates to global climate change. Specifically, the difference in timing between the central and western CLP may have been related to shifts in the position of the East Asian summer monsoon rain belt, due to the changing longitudinal position of the Western Pacific Subtropical High, together with changes in the east-west thermal gradient in the equatorial Pacific (i.e. shifts between La Nina and El Nino conditions).

Eolian sediments are widely distributed and are one of the most important geological archives of past climatic changes. For example, the degree of pedogenic development of loess is widely used as an indicator of precipitation amount. However, in the case of arid lands, characterized by drought conditions and where potential evaporation is much higher than precipitation, it is unclear whether precipitation is the sole factor dominating pedogenic development, or whether temperature is also an important factor affecting for pedogenic development. In this study, we compared variations in pedogenic development of sequences of Holocene eolian sediments in arid basins and humid high mountains in Northwest China to assess the role of precipitation and temperature in soil development. The results indicate that the variation trend of pedogenic development was similar in both arid basins and high mountains, with weak development in the early Holocene and gradually increasing development into the late Holocene. In addition, combining both temperature and moisture records reveals that the weakest soil development was in the early Holocene when the climate was warm and dry and the strongest soil development was in the late Holocene when the climate was warm and humid. Overall, our results reveal that precipitation was the dominant climatic factor controlling changes in pedogenic development in the study area.

K-feldspar pIRIR dating was used to establish a chronological framework for the KS15-05 loess section in the Yili Basin, northern Xinjiang Province, China, in arid central Asia. The reliability of the dating results was verified from the luminescence characteristics and internal checks. The chronology was used to calculate mass accumulation rates (MARs) for the section and the paleoclimatic proxies of grain size and magnetic susceptibility were also analyzed. The high dust accumulation patterns during the last glacial maximum in Yili Basin are consistent with those of the Chinese Loess Plateau (CLP). On a millennial-scale, the Bolling-Allerod (B/A) interstadial is clearly reflected in the KS15-05 section by the variation of the 2–10 μm grain-size fraction, suggesting the influence of the Westerlies which dominate the modern atmospheric circulation of the region. However, the B/A interstadial is poorly recorded in grain-size records of the CLP and this disparity may provide additional information about the nature of the transmission of climate signals from the North Atlantic region to Asia. Specifically, the zonal transmission of the B/A warm signal to the CLP may have been obscured by the cooling effect of High-latitude cold air to the north of the CLP.

Central Asia comprises a vast area of arid terrain which has an important impact on the global climate system. Although still debated, the pattern of climatic variations in central Asia is regionally distinctive and does not appear to be strongly related to changes in insolation. To understand the climatic evolution of central Asia, as well as its forcing mechanisms, it is necessary to characterize variations in the Westerlies, which have had a major influence on climate change in the region. Past variations in the Westerlies are commonly reconstructed from records of the composition, grain-size and mass accumulation rate (MAR) of loess and the eolian component of lacustrine sediments which are commonly mixed by the signal of surface atmospheric circulation. Here we present the results of grain-size analysis of a section of last glacial and Holocene loess deposits in the Tien Shan Mountains. The results indicate that the strength of the Westerlies was weakest during the last deglacial and early Holocene (16–6 ka), strongest during the mid-Holocene (6–3.1 ka), and moderate during the late Holocene (3.1–0 ka). By comparison with an independent record of humidity, we propose that the Westerlies were an important driver of moisture variations in central Asia, with strong Westerlies circulation resulting in high precipitation and vice versa during the past 16 kyr.

The East Asian summer monsoon (EASM) and East Asian winter monsoon (EAWM) are major drivers of environmental conditions in East Asia. However, due to the lack of high-resolution EAWM records, the phase relationship between the EASM and EAWM during the Holocene epoch is still debated. Here, we use magnetic and grain-size measurements from a sequence of aeolian sediments from the eastern edge of the Mu Us Desert to track the history of the EASM and EAWM from 7.5 to 2.5 ka. The results show that both the EASM and EAWM exhibit a similar long-term weakening trend during this interval. In view of the stable glacial boundary conditions and the significantly decreased rates of atmospheric CO 2 rise since the mid-Holocene, we suggest that orbitally-induced insolation was the major cause of the weakening of both the EASM and EAWM. Decreasing summer insolation and increasing winter insolation reduced the thermal contrast between the ocean and the Asian continent in both summer and winter time, resulting in the weakening of both monsoon systems during the mid- to late Holocene.

The expansion of poisonous plants can change vegetation community structures and affect grassland ecosystem service values. Stellera chamaejasme is one of the most important poisonous plants and has rapidly expanded in the arid areas of Northwest China in recent decades. The objective of this study was to elucidate the expansion process and model of an S. chamaejasme population. Therefore, we classified the S. chamaejasme population into five classes based on coverage: 31–40%, 41–50%, 51–60%, 61–70% and 71–80%. We investigated the spatial distribution patterns and the size compositions of S. chamaejasme under different coverages. The results show that the spatial distribution pattern of S. chamaejasme under low coverage (31–40%) at all study scales (0–100 cm) was random; the spatial distribution pattern translated to a clumped distribution from a random distribution at some scales, and the clumped distributions gradually became obvious, with coverage increasing from 41–50% to 61–70%; the spatial distribution tended to be random at all study scales when coverage was increased further (71–80%). However, the spatial distribution patterns were closely related to the size composition of the S. chamaejasme population. In particular, the quantity of older individuals had a significant impact on the variation of the spatial distribution patterns of S. chamaejasme. The spatial distribution pattern varied from a random distribution to a clumped distribution and then returned to a random distribution with increasing coverage (from 31–40% to 71–80%), and this may indicate that the S. chamaejasme patches experienced patch formation and extension and merged with each other.

Previous studies from the central and eastern Chinese Loess Plateau (CLP) showed that the S5-1 paleosol, which corresponding to Marine Isotope Stage (MIS) 13, was the strongest developed during the last million years, suggesting extremely strong East Asian summer monsoon (EASM). However, evidence shows that regional diversity exists in the relative intensity of the S5-1 soil formation. In this study, we first verify systematically the S5-1 soil development across the whole CLP by using numerous loess records. We then examine the spatial variation of the magnetic susceptibility of different loess-paleosol sections to identify the spatial change of the EASM intensity during MIS-13. We also compare the loess records with other monsoon records in China. Our results show that, in central CLP, S5-1 is indeed the strongest developed as suggested by previous studies, whereas in the western CLP, it is weakly developed and the S4 paleosol developed during MIS-11 is the strongest. As compared to MIS-11, the northern front of the EASM during MIS-13 didn’t penetrate into western CLP, but was located more northerly and eastward. Based on sea surface temperature records in the tropical Pacific, we suggest that the temporal and spatial abnormal variation of the EASM during MIS-13 could be related to a strong La Nina or La Nina-like climate condition. Under such condition, the Western Pacific Subtropical High (WPSH) becomes weaker and retreats more northeastward, leading to more precipitation in the mid-east region of northern China but less rainfall in the western inland.