Agricultural adaptations to topography and climate changes in Central China during the mid- to late-Holocene

The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Xin Jia ◽  
Haiming Li ◽  
Harry F Lee ◽  
Zhen Liu ◽  
Yong Lu ◽  
...  

The development of pre-historic agriculture and its determining factors have been extensively investigated in recent years. Based on the identification of charred seeds and radiocarbon dating, we found that foxtail millet-based agriculture dominated Neixiang County in Central China during the mid-late-Holocene. There were three different farming patterns in the Nanyang Basin, including rice cultivation in the plains, foxtail millet cultivation in the pediment plains, and broomcorn millet cultivation in the valleys. In addition, during the Neolithic-Bronze Age, the distribution of human settlements with rice cultivation matched with the climate pattern at 31.0–36.5° N in China. The emergence of rice cultivation had been facilitated by a significant increase in East Asian summer monsoon and increased precipitation in Central China since 8500 BP and gradually flourished during the Peiligang (8500–7000 BP) and Yangshao (7000–4500 BP) Period, corresponding to a relatively warm and wet climate. However, the average latitude of the human settlements with rice cultivation shifted southward to 33.29° N during the Longshan Period (4500–4000 BP) due to the cold climate brought by the “4.2 ka event.” Afterward, rice cultivation was basically not constrained by climate change, probably owing to the improved farming methods in the Bronze Age.

2021 ◽  
Vol 9 ◽  
Author(s):  
Yaping Li ◽  
Junna Zhang ◽  
Xiaohu Zhang ◽  
Haitao Zhao

In northern China, the Yangshao cultural period (5000–3000 BC) was a critical timespan in the establishment of agricultural economies and the emergence of social complexity. We present the results of archeobotanical analysis from 58 soil samples collected from 12 recently investigated sites located in the Luoyang Basin, and recovered 5290 carbonized plant remains from 9 sites dating to the Late Yangshao period. We compared our novel dataset with previous archeobotanical date, compiling a total of 196 samples from 58 sites in central and western Henan Province. During the Early Yangshao period (5000–4200 BC), a nascent, extensive agricultural economy based primarily on broomcorn millet, with lesser foxtail millet and rice, was developing in small settlements (<0.2 km2) in the loess tablelands and valleys of western Henan province. However, the population pressure—rather than environmental degradation—drove the “foxtail millet-broomcorn millet substitution” during the Middle Yangshao period (4200–3500BC). The intensive agriculture based mainly on foxtail millet facilitated the development of social complexity in the region, as demonstrated by the emergence of size-graded agricultural settlements of medium (0.2–0.6 km2) and large (> 0.6 km2) scale. Notably, millets tend to be less ubiquitous in these larger settlements compared to smaller ones, with differences in millet ubiquity between sites increasing over time. The local surface hydrology influenced by paleoclimatic changes prompted the spread of agriculture from higher loess tablelands and valleys during the early Yangshao period into more marginal loess tablelands and plains by the Middle and Late Yangshao periods. Rice cultivation is concentrated in valley areas and appears to have been closely tied to environments with better hydrothermal conditions. Our research shows that climatic conditions during the Holocene fostered the development of agriculture during the Yangshao Culture period and that the distribution of settlements throughout this time was influenced by highly localized geomorphologic environments delimiting the distribution of crops. The rise of agriculture promoted the formation of complex and stratified economies in the Yangshao Culture period and it was the intensification and elaboration of these new economic and social systems that led to later transformation in agricultural structures and settlement sizes.


The Holocene ◽  
2020 ◽  
Vol 30 (9) ◽  
pp. 1254-1265 ◽  
Author(s):  
Lucie Juřičková ◽  
Petr Šída ◽  
Jitka Horáčková ◽  
Vojen Ložek ◽  
Petr Pokorný

We studied the transformation of a middle-to-late Holocene forested ecosystem using the highly indicative remains of land snails. The study areas were sandstone landscapes of northern Bohemia (Czech Republic) that provide extremely rich terrestrial fossil records. As far as we know, nowhere else in the world does such a type of sedimentary environment provide Holocene records of snail shells. Currently, these sandstone landscapes are covered by low productivity coniferous forests with very low species pools. In sharp contrast, in the middle Holocene, they were dominated by species-rich productive woodland communities. Such ecosystems were then supported by a favourable warm and wet climate and by nutrient-rich, calcareous substrata formed of late Pleistocene aeolian dust (loess). A radical transformation of this temporal ecological equilibrium began in the third millennium BC. Over the next millennia, the species-rich canopy forest mollusc assemblages almost completely disappeared, together with calciphilous rock dwellers. The main driving force of this transformation was gradual soil leaching that resulted in the loss of calcium carbonate and principal nutrients (like P and N) and subsequent ecosystem retrogression. Synergistically with this background trend, the unstable climatic regime of the late Holocene, along with long-term anthropogenic pressure that peaked for the first time during the late Bronze Age, accelerated the transformation.


2021 ◽  
Vol 9 ◽  
Author(s):  
Xueyun Ma ◽  
Zhifu Wei ◽  
Yongli Wang ◽  
Gen Wang ◽  
Ting Zhang ◽  
...  

Hydroclimate evolution history and changes in the Tibetan Plateau play significant roles in depicting paleoclimate and evaluating climatic conditions in the coming future. However, the interaction of the westerlies and the Asian monsoon complicates our understanding of the mechanism of climate variation over the Tibetan Plateau. In this study, we assessed the paleoclimate of Hurleg Lake, which was previously located in the convergence area of the East Asian monsoon and westerly wind. We first reconstructed the climatic conditions based on fined-grained authigenic carbonate δ18O (δ18Ocarb), plant-derived proxies of C/N, and n-alkane-derived δ13C31. In the Hurleg Lake, δ18Ocarb was controlled by δ18O changes of the lake water and evaporation. The climate evolution since ∼16.1 cal kyr BP can be classified into three stages. The Lateglacial (16.1–11.0 cal kyr BP) was characterized by a warm-wet climate in the beginning, followed by a cold-dry climate since 12.0 cal kyr BP. Typical warm and cold phases occurred during 14.8–12.0 cal kyr BP and 12.0–11.1 cal kyr BP, which may correspond to the Bølling/Allerød (B/A) and Younger Dryas periods, respectively. The early to mid-Holocene was generally characterized by a warm-wet climate; however, notable cold-dry intervals occurred at ∼8.3 cal kyr BP. The Late Holocene (after 4.8 cal kyr BP) displayed a significantly cold-wet climate. Finally, we examined the possible mechanisms responsible for the climate variability in the study area. The results showed that the long-term warm trend in the Lateglacial and colder trend after early Holocene was controlled by insolation. The Asian summer monsoon and the westerlies played a significant role in determining moisture sources during the Lateglacial. The East Asian monsoon contributed greatly to the moisture variation from the early to mid-Holocene, whereas the westerly winds dominated during the late Holocene. Combined, our findings highlight the complex changes in hydroclimate conditions since the last glacial in the Tibetan Plateau and provide crucial implications for comprehending the hydroclimate pattern in the transition zone of westerlies and Asian monsoon.


2020 ◽  
Vol 95 ◽  
pp. 84-96
Author(s):  
Gang Xu ◽  
Jian Liu ◽  
Marcello Gugliotta ◽  
Yoshiki Saito ◽  
Lilei Chen ◽  
...  

AbstractThis paper presents geochemical and grain-size records since the early Holocene in core ECS0702 with a fine chronology frame obtained from the Yangtze River subaqueous delta front. Since ~9500 cal yr BP, the proxy records of chemical weathering from the Yangtze River basin generally exhibit a Holocene optimum in the early Holocene, a weak East Asian summer monsoon (EASM) period during the middle Holocene, and a relatively strong EASM period in the late Holocene. The ~8.2 and ~4.4 cal ka BP cooling events are recorded in core ECS0702. The flooding events reconstructed by the grain-size parameters since the early Holocene suggest that the floods mainly occurred during strong EASM periods and the Yangtze River mouth sandbar caused by the floods mainly formed in the early and late Holocene. The Yangtze River-mouth sandbars since the early Holocene shifted from north to south, affected by tidal currents and the Coriolis force, and more importantly, controlled by the EASM. Our results are of great significance for enriching both the record of Holocene climate change in the Yangtze River basin and knowledge about the formation and evolution progress of the deltas located in monsoon regions.


2021 ◽  
Vol 13 (9) ◽  
pp. 4848
Author(s):  
Liwei Wu ◽  
Xinling Li ◽  
Qinghai Xu ◽  
Manyue Li ◽  
Qiufeng Zheng ◽  
...  

The East Asian monsoon system is an important part of global atmospheric circulation; however, records of the East Asian monsoon from different regions exhibit different evolutionary rhythms. Here, we show a high-resolution record of grain size and pollen data from a lacustrine sediment core of Dajiuhu Lake in Shennongjia, Hubei Province, China, in order to reconstruct the paleovegetation and paleoeclimate evolution of the Dajiuhu Basin since the late Middle Pleistocene (~237.9 ka to the present). The results show that grain size and pollen record of the core DJH-2 are consistent with the δ18O record of stalagmites from Sanbao Cave in the same area, which is closely related to the changes of insolation at the precessional (~20-kyr) scale in the Northern Hemisphere. This is different from the records of the Asian summer monsoon recorded in the Loess Plateau of North China, which exhibited dominant 100-kyr change cyclicities. We suggest that the difference between paleoclimatic records from North and South China is closely related to the east–west-oriented mountain ranges of the Qinling Mountains in central China that blocked weakened East Asia summer monsoons across the mountains during glacial periods.


2021 ◽  
Vol 558 ◽  
pp. 116758
Author(s):  
Yanjun Cai ◽  
Xing Cheng ◽  
Le Ma ◽  
Ruixue Mao ◽  
Sebastian F.M. Breitenbach ◽  
...  

The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Valentí Rull ◽  
Núria Cañellas-Boltà ◽  
Teresa Vegas-Vilarrúbia

Palynological analysis of the last ca. 4300 cal year BP using a sediment core taken from high mountain (ca. 1900 m elevation) Lake Sant Maurici sediments (southern-central Pyrenees) showed remarkable vegetation constancy during the Bronze Age and the Middle Ages. Records of the Iron Age and the Roman period were missing due to a major sedimentary gap. During the studied periods, the vegetation around the lake was largely dominated by pine ( Pinus) forests with birch ( Betula), oak ( Quercus) and hazel ( Corylus) trees, as is the case today. The composition of these forests and the abundance of their components remained quite stable, despite the occurrence of temperature and moisture shifts. The degree of human disturbance, notably that of pastoralism and cereal cultivation by scattered and temporary settlements, was very low and had little or no effect on the dominant forests. This situation contrasts with most high-elevation (subalpine and alpine) environments of the central Pyrenees that were massively anthropized during the Middle Ages. Further research should be aimed at finding sediments corresponding to the Iron Age and the Roman period to verify whether the vegetation constancy can be extended throughout the Late-Holocene. Past records of this type may allow the estimation of natural and anthropogenic thresholds for irreversible forest changes, which would be useful for conservation purposes.


The Holocene ◽  
2016 ◽  
Vol 26 (12) ◽  
pp. 1924-1938 ◽  
Author(s):  
Yuji Ishii ◽  
Kazuaki Hori ◽  
Arata Momohara ◽  
Toshimichi Nakanishi ◽  
Wan Hong

This study investigated the influence of sea-level and climate changes on the decreased fluvial aggradation and subsequent widespread peat initiation in the middle to late-Holocene in the Ishikari lowland, which is a coastal floodplain formed in response to the postglacial sea-level change. By introducing a new approach to separately evaluate the rates of organic and clastic sediment input, we demonstrated that the peat began to form when the fluvial sedimentation rate was significantly decreased (less than 0.6 mm/yr), while plant macrofossil analysis suggested that lowering of water level is also important to the peat initiation. Such changes in sedimentary environment may be associated with the abrupt abandonment of crevasse splays. The concentrated ages of the peat initiation around 5600–5000, 4600–4300, and 4100–3600 cal. BP suggest that an allogenic control promoted the abandonment of crevasse splays, and different onset ages can be explained by different fluvial responses of the Ishikari River and its tributaries. The abandonment of crevasse splays could result from sea-level fall or decreased precipitation. While submillennial sea-level fluctuations coincident with the peat initiation have not been reported in coastal lowlands of Japan, the close comparison of the onset ages and decreased precipitation recorded in a stalagmite from China, which represents the strength of the East Asian summer monsoon (EASM), suggests that decrease in precipitation led to the abandonment of crevasse splays. Our results may indicate that similar fluvial responses might be common in other coastal floodplains affected by the EASM.


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