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Human activity on arid lands has been related to oases evolution. The ancient Loulan, an important transportation hub of the ancient Silk Road, developed on an ancient oasis on the west bank of the lake Lop Nur in Xinjiang, China. Previous studies and historical documents suggest that the region has experienced dramatic natural environmental and human activity--related changes over time, transitioning from a particularly prosperous oasis to a depopulated zone with harsh environment after about 1500 a BP (before present, where present = AD 1950). Based on systematic radiocarbon (14C) dating for natural plant remains and archeological sites in the Loulan area, it was revealed that the region re-experienced oasis environment from 1260 to 1450 cal. AD, corresponding to the Yuan--Ming Dynasties, which is the climate transition stage from the 'Medieval Warm Period' to the 'Little Ice Age', encompassing a series of pulse-like flood events which cannot be identified from lacustrine deposition due to the limits of sampling resolution and dating. It was found that humans re-occupied the Loulan area and built canals to irrigate farmlands during the period. The more habitable hydrological conditions that resulted from these environmental changes present one major reason for the re-emergence of human activities in the Loulan area. [ABSTRACT FROM AUTHOR]

Mixed millet and rice agriculture is a unique agricultural style of China, and is distributed in a broad band between the Yangtze and Yellow River basin. However, the development of this style during the Neolithic-Bronze Age has not been comprehensively clarified, owing to limited archaeobotanical data and imprecise chronology for most of the regions. Here, the Central Plain, a location where mixed agriculture may have first appeared, was selected as the area for research. Phytolith and macrofossil analyses from the Zhuzhai site, together with the accelerator mass spectrometer (AMS) radiocarbon dating of samples, reveal information about the temporal changes of mixed agriculture as well as the domestication and cultivation of crops in this region. The results indicate that mixed millet and rice agriculture formed in the Central Plain about 8000 years ago. Common millet was the principal crop in the Peiligang and Yangshao periods, with the domestication process beginning in the Peiligang period and continuing up to the Shang period, at which time it was replaced by foxtail millet. Foxtail millet may have gone through a significant degree of domestication by ca. 6000 cal. BC, but its domestication process was still unclear. Rice had appeared since the Peiligang period, but its proportions were always low. Rice assigned to the Peiligang and Yangshao Cultures was the domesticated japonica, and its cultivation was always performed in dry field systems through the Neolithic-Bronze time. Within the subsistence economy, mixed agriculture was a minor component during the Peiligang period, but has been dominant since the Yangshao period. [ABSTRACT FROM AUTHOR]

This study presents the first direct evidence of millet cultivation in Neolithic southeast coastal China. Macroscopic plant remains and phytoliths, together with direct accelerator mass spectrometry (AMS) radiocarbon dates on crops, have shown that both foxtail millet and broomcorn millet were cultivated with rice in the Huangguashan and Pingfengshan sites in Fujian province around 4000-3500 cal. BP. Ratios of different parts of crop remains revealed that crop processing activities such as dehusking and sieving were conducted within the site and thus demonstrated the local production of these crops. The new data, especially the discovery of foxtail millet and broomcorn millet, have greatly changed the current knowledge about the ancient distribution of millet in South China and have now identified southeast China among the potential source-region of Neolithic crops transported overseas to Taiwan and Island Southeast Asia. This study further draws a potential dispersal route of Austronesian languages and people from southern China through Taiwan throughout Southeast Asia. [ABSTRACT FROM AUTHOR]

Compared with the monistic structure of crop agriculture in Southwest Asia and Mesoamerica, agriculture in ancient China reflects the characteristics of a dualistic structure with millet in the north and rice in the south. It is argued that the rice and millet farming modes were mutually exchanged during their development and formed a vast region of mixed farming. However, the time and place of its origin, the routes of dissemination, and the development patterns and possible influence factors of mixed farming remain unclear. This study systematically collected information from 804 sites with millet and rice records and detailed floatation results from 78 mixed farming sites in prehistoric China. Three north-south communication corridors are identified between the upper, middle and lower Yellow and Yangtze River Valleys that began around 5500 BP, 8400 BP and 4600 BP, respectively. Cultural communication accompanied by human migration and the unique natural environment of loess and East Asia monsoons facilitated the interaction between millet and rice farming through these corridors. As a comprehensive reflection of the interaction between millet and rice farming, the crop structure of the four core mixed farming regions is in a continual process of adjustment, with the selection of foxtail millet in the southward spread of millet agriculture and temperate Oryza japonica in the northern spread of rice agriculture. [ABSTRACT FROM AUTHOR]

Fossil pollen from Nam Co and modern pollen from altitudinal vegetation belts around the lake are investigated to reveal alpine vegetation succession in response to climate changes during the Holocene in the central Tibetan Plateau. The discriminant analysis on 37 topsoil samples shows that pollen samples from alpine steppe at lower elevations (<4800 m) and alpine meadow on upper slopes (4800–5200 m) can be distinguished by their pollen assemblages. Samples from alpine steppe contain more Artemisia (25.1%) and Poaceae pollen (11.5%), whereas those from alpine meadow are dominated by Cyperaceae pollen (>60%). Our result indicates that the pollen ratio of Artemisia to Cyperaceae (A/Cy) can be used as an indicator of the vertical shift of vegetation belts and temperature changes in the central Tibetan Plateau as suggested by previous studies. A history of the vertical shift of vegetation belts on the northern slope of Nyainqentanglha Mountains and climate changes since 8.4 kyr BP are thus recovered by 198 fossil pollen assemblages from a 332 cm core of Nam Co. Paleovegetation reconstructed from fossil pollen assemblages through discriminant analysis shows a general downward shift of altitudinal vegetation belts, suggesting a decline in the temperature trend since 8.4 kyr BP. This result is consistent with the reduction of A/Cy ratios. The fossil pollen record also reveals warm and wet climate during the early to mid Holocene, and cold and dry conditions during the late Holocene in the Nam Co area. A comparison of Holocene climatic reconstructions across the Plateau indicates that termination of maximum moisture at around 6–5.5 kyr BP in our record is associated with the southeastward retreat of the Southwest Monsoon. [ABSTRACT FROM AUTHOR]