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The mechanisms of the origin and dispersal of millet agriculture in northern China are poorly understood. We used plant macroremains, stable isotope compositions of human bone collagen, and pollen records from the Sitai site to reconstruct changes in subsistence strategies and their relationship with the ecological environment from the early to middle Holocene on the Inner Mongolian Plateau in northern China. Charred weed-like seeds, the bones of small mammals, eggshell fragments, together with microliths, indicate the practice of hunter-gatherer subsistence strategies during 10,500–10,200 cal yr BP. Deciduous broadleaved forest-steppe vegetation was present around the Sitai site during the early middle Holocene (8000–7000 cal yr BP). Additionally, isotopic compositions of human bones and plant remains reveal that millet agriculture and hunting-gathering appeared in the early middle Holocene. The spread of millet agriculture on the Inner Mongolian Plateau was likely favored by an increase in precipitation between 8000 and 7000 cal yr BP. The development of millet agriculture on the Inner Mongolia Plateau and the Loess Plateau was the prelude to its subsequent spread to the Tibet Plateau.

The question of what the ecology communities of the Loess Plateau looked like before the extensive anthropogenic reshaping processes of the late-Holocene has stirred a long debate. A better understanding of these human-induced changes will not only help us understand the extent of paleoeconomic practices, but also inform future conservation actions on this ecologically fragile landscape. This paper presents a systematic study of wood charcoal from a series of archaeological sites, demonstrating that woody plants and woodlands were widely distributed and geographically diverse on the Loess Plateau in response to the East Asian Monsoon. In the Guanzhong Basin, oak ( Quercus spp.) woodlands were associated with a few tropical-subtropical taxa, which changed to oak and pine ( Pinus spp.) mixed forests on the eastern plateau, while on the northern plateau coniferous woodlands were dominant. On the western Loess Plateau, oak and elm ( Ulmus spp.) woodland and spruce ( Picea spp.) forests were widespread. The charcoal results suggest that human impacts on the dominant species might have begun as early as ca. 3500 cal yr BP, with oak replaced by Prunus as the dominant taxon, including many economically significant species, such as peaches ( P. persica) and apricots ( P. armeniaca). Furthermore, the charcoal data show that due to warm and wet climatic conditions in the mid-Holocene, the distribution of tropical-subtropical taxa shifted markedly northwards into the Guanzhong and Tianshui Basins, and the central part of the eastern Loess Plateau, which became characterized by high frequencies of Bamboo.

Based on identification of fossil charcoals from 11 sites in the Hexi Corridor, we reconstruct the local vegetation community and human impact on it in the period from 4300 to 2400 cal. yr BP. More...

Understanding the features of the paleoclimate and paleoenvrionment from key areas is crucial for predicting the climate variation of the future. In this study, fossil charcoal coupled with high-accuracy accelerator mass spectrometry (AMS) 14C dating from the Guanzhong Basin is analyzed to reconstruct the paleoclimate. Here, the coexistence approach (CA) was applied, and the result showed that the mean annual temperature (MAT) was about 14.8°C, and the annual precipitation (AP) was about 831.1 mm in the Guanzhong Basin during 6200–5600 cal. a BP. Comparing the climate between the mid-Holocene and present in the Xi’an area, the MAT was about 1.1°C higher than today and the AP was about 278 mm higher than today, similar to the modern climate of the Hanzhong area in the southern Qinling Mountains.

Knowledge of the millennial abrupt monsoon failures is critical to understanding the related causes. Here, we extracted proxy indices of Indian Summer Monsoon (ISM) intensity during the early to mid-Holocene, from peat deposits at Lake Xihu, in southwestern China. There are a series of abrupt, millennial-scale episodes of ISM weakening inferred from the Lake Xihu records, which are generally synchronous with those inferred from other archives over ISM areas. An important feature is that the ISM failures inferred from the Lake Xihu proxy indices synchronize well with abrupt changes in solar activity. We argue that changes in solar activity play a primary role in producing most of these millennial ISM failures, while some other causes, including freshwater outbursts into the North Atlantic Ocean and changes in sea surface temperatures of the eastern tropical Pacific Ocean, may have also exerted influences on parts of the millennial ISM failures.

People in northern and western China were probably the first in the world to use coal as a source of energy in a consistent way. The ages cluster around 1900–2200 bc in modern day Inner Mongolia and Shanxi provinces. These are areas where near-surface coal is abundant today and woody vegetation was scant in the Bronze Age. Since coal is bulky to transport, it was probably not a cost-effective energy source in areas with abundant wood supply. The sites where coal was first used were probably occupied for a century to a few centuries at most and were associated with Bronze Age societies. The earliest age is about 3490 bc from a house site at Xiahe in Shaanxi Province; however, the coal is not securely tied to the radiocarbon ages and is assumed to have been used at this site sometime after 3490 bc. The elemental composition of modern mine and sedimentary coal in nearby archaeological contexts suggests that coal was used from local sources, and that elemental composition of coal may be a useful tool in identifying site origin of coal.

Based on published pollen data from 44 sites in the Loess Plateau and surrounding areas, we recalculate values of Picea abundance digitized from the original diagrams and construct six isopoll maps to reconstruct the distribution of spruce forest at 2000 yr intervals during the Holocene. Spruce forest gradually expanded from about 10 ka BP ago and reached its peak distribution around 8 ka BP. It retained its maximum extent between 8 ka BP and 6 ka BP, broadly covering the subalpine area and stretching to the valleys of the western Loess Plateau with high densities and even reaching the edges of the adjacent desert regions. After 6 ka BP, spruce forest began to retreat to higher elevations. This trend was accelerated after 4 ka BP. After 2 ka BP, it disappeared completely from the Loess Plateau and most of its surrounding areas. Precipitation strongly dominated by the Asian summer monsoon was the primary controlling factor in the distribution of spruce before 2 ka BP. After about 2 ka BP, the increasing intensity of human activity became the primary factor in the disappearance of spruce in the Loess Plateau, resulting in an enormous impact on the present landscape.

The emergence and rapid spread of agriculture from the early Holocene has made a great impact on the development of human societies and landscape change. Guanzhong Basin in the middle of Yellow River valley has a long continuous history of agriculture since the Neolithic. The pollen and charcoal records from Xindian in western Guanzhong Basin, together with the known distribution of archaeological sites, provide proxies to reconstruct the history of agricultural activity and landscape change. The concentration and percentage of Poaceae pollen increase from about 7700 yr BP ago and the concentration of charcoal shows the same trend. These records indicate that the ‘slash-and-burn’ cultivation for agriculture began around 7700 years ago. Between 7700 and 5500 yr BP, the evidence of cereal crops remained strong and charcoal concentration and archaeological sites increased greatly, which all indicate increased agricultural activity and the expansion of human populations. This was enhanced by the continuous development of new cultivation tools and techniques between 4700 and 3300 yr BP, especially in the Bronze Age of the pre-Zhou Dynasty. The original agricultural landscape had been settled after 3300 yr BP. Buckwheat became an important crop from around 5500 yr BP, perhaps because of increasing aridity. This is the earliest record of cultivated buckwheat in Neolithic China.

Evidence for cultivated wheat at 4650 cal. yr BP, as part of a broadening agricultural-based society (4650—4300 cal. yr BP), is presented from Xishanping in northwest China. This was established from archaeobotanical evidence and radiocarbon dating. Crops from SW Asia had therefore been adopted in China about 2500 years earlier than previously thought, and long before the `Silk Road' route was known to be used. The data show that the early infiltration and blending of agriculture involving rice, buckwheat, barley, millet and wheat occurred in this region. This raises questions as to why crops from China do not appear further westward at this time and how the blending of agricultural practices contributed to the development of Chinese civilization.