Recently, when evaluating the achievements China has made during the his- torical periods before and after reform and opening-up, Chinese President Xi Jinping pointed out, "The socialist construction conducted by the...Recently, when evaluating the achievements China has made during the his- torical periods before and after reform and opening-up, Chinese President Xi Jinping pointed out, "The socialist construction conducted by the people under the leadership of our Party is divided into two historical periods--before and after reform and opening-up. The two periods are in- terconnected, but also different from each other. However, they both essen- tially reflect the practical explorations of socialist construction conducted by the people under the leadership of the Party. Socialism with Chinese characteristics began to take shape in the new era of reform and opening- up, but it is also grounded in New China's 20-plus years of experience in building and carrying out the basic system of socialism... Although the two historical periods have huge dif- ferences in the guidelines, policies,展开更多
The diurnal temperature range(DTR) serves as a vital indicator reflecting both natural climate variability and anthropogenic climate change. This study investigates the historical and projected multitemporal DTR varia...The diurnal temperature range(DTR) serves as a vital indicator reflecting both natural climate variability and anthropogenic climate change. This study investigates the historical and projected multitemporal DTR variations over the Tibetan Plateau. It assesses 23 climate models from phase 6 of the Coupled Model Intercomparison Project(CMIP6) using CN05.1 observational data as validation, evaluating their ability to simulate DTR over the Tibetan Plateau. Then, the evolution of DTR over the Tibetan Plateau under different shared socioeconomic pathway(SSP) scenarios for the near,middle, and long term of future projection are analyzed using 11 selected robustly performing models. Key findings reveal:(1) Among the models examined, BCC-CSM2-MR, EC-Earth3, EC-Earth3-CC, EC-Earth3-Veg, EC-Earth3-Veg-LR,FGOALS-g3, FIO-ESM-2-0, GFDL-ESM4, MPI-ESM1-2-HR, MPI-ESM1-2-LR, and INM-CM5-0 exhibit superior integrated simulation capability for capturing the spatiotemporal variability of DTR over the Tibetan Plateau.(2) Projection indicates a slightly increasing trend in DTR on the Tibetan Plateau in the SSP1-2.6 scenario, and decreasing trends in the SSP2-4.5, SSP3-7.0, and SPP5-8.5 scenarios. In certain areas, such as the southeastern edge of the Tibetan Plateau, western hinterland of the Tibetan Plateau, southern Kunlun, and the Qaidam basins, the changes in DTR are relatively large.(3) Notably, the warming rate of maximum temperature under SSP2-4.5, SSP3-7.0, and SPP5-8.5 is slower compared to that of minimum temperature, and it emerges as the primary contributor to the projected decrease in DTR over the Tibetan Plateau in the future.展开更多
The spatial resolution of source data, the impact factor selection on the grid model and the size of the grid might be the main limitations of global land datasets applied on a regional scale. Quantitative studies of ...The spatial resolution of source data, the impact factor selection on the grid model and the size of the grid might be the main limitations of global land datasets applied on a regional scale. Quantitative studies of the impacts of rasterization on data accuracy can help improve data resolution and regional data accuracy. Through a case study of cropland data for Jiangsu and Anhui provinces in China, this research compared data accuracy with different data sources, rasterization methods, and grid sizes. First, we investigated the influence of different data sources on gridded data accuracy. The temporal trends of the History Database of the Global Environment (HYDE), Chinese Historical Cropland Data (CHCD), and Suwan Cropland Data (SWCD) datasets were more similar. However, differ- ent spatial resolutions of cropland source data in the CHCD and SWCD datasets revealed an average difference of 16.61% when provin- cial and county data were downscaled to a 10 x 10 km2 grid for comparison. Second, the influence of selection of the potential arable land reclamation rate and temperature factors, as well as the different processing methods for water factors, on accuracy of gridded datasets was investigated. Applying the reclamation rate of potential cropland to grid-processing increased the diversity of spatial distri- bution but resulted in only a slightly greater standard deviation, which increased by 4.05. Temperature factors only produced relative disparities within 10% and absolute disparities within 2 km2 over more than 90% of grid cells. For the different processing methods for water factors, the HYDE dataset distributed 70% more cropland in grid cells along riverbanks, at the abandoned Yellow River Estuary (located in Binhai County, Yancheng City, Jiangsu Province), and around Hongze Lake, than did the SWCD dataset. Finally, we ex- plored the influence of different grid sizes. Absolute accuracy disparities by unit area for the year 2000 were within 0.1 km2 at a 1 km2 grid size, a 25% improvement over the 10 km2 grid size. Compared to the outcomes of other similar studies, this demonstrates that some model hypotheses and grid-processing methods in international land datasets are truly incongruent with actual land reclamation proc- esses, at least in China. Combining the model-based methods with historical empirical data may be a better way to improve the accuracy of regional scale datasets. Exploring methods for the above aspects improved the accuracy of historical crop/and gridded datasets for finer regional scales.展开更多
Lop Sea,located at the east end of the Tarim Basin,Northwest China,dried up permanently,which is the terminal lake of the Tarim River.Lop Sea was considered as the lake basin of Lop Nor since Quaternary.However,the po...Lop Sea,located at the east end of the Tarim Basin,Northwest China,dried up permanently,which is the terminal lake of the Tarim River.Lop Sea was considered as the lake basin of Lop Nor since Quaternary.However,the possibility that Lop Nor was away from the Lop Sea in historical time is crucial to be discussed to interpret the proxy records in sediment profiles.To obtain a general view of the evolution of Lop Nor and Lop Sea in a historical period,several approaches were adopted in this paper.First,the Qianlong Thirteen-Row Atlas,an ancient imperial atlas of the Qing Dynasty,which was completed around 1760,indicated that the Tarim River formed a relatively large lake at its modern upstream region.Second,a Digital Elevation Model(DEM)with a 10-m spatial resolution and a relative precision of 0.42 m was derived from TanDEM-X/Terra SAR-X satellite image pairs using the interferometry method,which was verified using ICESat-GLAS laser footprints and a local DEM acquired by a drone.Finally,based on the spatial analysis of historical documents,expedition reports,sediment profiles and archaeological evidence,it can be deduced that the lacustrine deposition was discontinued in the Lop Sea.Six episodes in the evolutionary history of the drainage system in eastern Tarim Basin were summarized.The proved depositional condition variations could be used for future interpretation of proxy records in sediment.The high-accurate DEM provided a reference for the location of further fieldwork in the Lop Sea.The method proposed in this paper may be efficient for the research of inland lakes or rivers in global arid regions.展开更多
This study applies ArcGIS to analyze the spatiotemporal distribution of cultural sites in the Ill River Valley in northwestern China. It explores relationships between the sites' spatiotemporal evolutionary character...This study applies ArcGIS to analyze the spatiotemporal distribution of cultural sites in the Ill River Valley in northwestern China. It explores relationships between the sites' spatiotemporal evolutionary characteristics, human history, and the natural environment. The results indicate that the numbers and proportions of the sites, and the frequency of their oc- currence, exhibited an inverted V-shaped change trend during six historical periods. The "high in the east and low in the west" spatial distribution pattern of the first three periods shifted to the one the "high in the west and low in the east" during the latter three periods, demonstrating a change in the spatial center of gravity of human activities. The sites were mainly distributed on slopes of grades 1-5, with their proportions increasing from 75% during the Spring and Autumn Period (770 BC-476 BC)-Qin Dynasty (221 BC-207 BC) to 93.75% during the Qing Dynasty-Modern period. The concentrated distribution of site elevations shifted from grades 4-8 during the Spring and Autumn Period-Qin Dynasty, and the Western Han (206 BC-8)-Southern and Northern Dynasties (420-589), to grades 1-4 during the latter three periods. The number of sites showed a shifting trend from high-elevation mountains and hills to low-elevation plains, and from high slopes to low slopes. In particular, the sites exhibited a special "moist" evolutionary pattern of migration from middle and upstream areas to downstream areas, as opposed to the migration pattern of sites located in typical arid areas. The study also considered factors influencing the distribution and spatiotemporal evolution of cultural sites, notably, human factors and natural factors.展开更多
Social responses to climate change over human history have been widely discussed in academia over the last two decades. However, the transformation of the human–environment nexus crossing prehistoric and historic per...Social responses to climate change over human history have been widely discussed in academia over the last two decades. However, the transformation of the human–environment nexus crossing prehistoric and historic periods and the processes associated with it are not yet clearly understood. In this study, based on published works on radiocarbon dating, archaeobotany, zooarchaeology, and archaeological sites, together with a synthesis of historical documents and highresolution paleoclimatic records, we trace the extent to which human settlement patterns in the Hexi Corridor in northwestern China evolved in conjunction with climate change over the last 5,000 years. A total of 129 Neolithic, 126 Bronze Age, and 1,378 historical sites in the Hexi Corridor(n=1,633) were surveyed. Our results show that, in the Late Neolithic and Bronze Age periods(~2800–100 BC), climate change contributed to the transformation of subsistence strategies and the subsequent changes in human settlement patterns in the Hexi Corridor. The warm-humid climate in ~2800–2000 BC promoted millet agriculture and helped the Majiayao, Banshan, and Machang Cultures to flourish. The cold-dry climate in ~2000–100 BC resulted in the divergence and transformation of subsistence strategies in the Xichengyi–Qijia–Siba and Shajing–Shanma Cultures and in a shift in their settlement patterns. However, in the historical period(121 BC–AD 1911), human settlement patterns were primarily determined by geopolitics related to the alternating rule of regimes and frequent wars, especially in the Sui–Tang dynasties. We also find that trans-Eurasian cultural exchange since ~2000 BC improved social resilience to climate change in the Hexi Corridor, mediating the human–environment nexus there. Our findings may provide insights into how human societies reacted to climate change in arid and semi-arid environments over the long term.展开更多
This paper focuses on the historical transition of human being's activities and the eco-environment in the upper reaches of Minjiang River. The history is divided into 4 periods, each with its own feature. During ...This paper focuses on the historical transition of human being's activities and the eco-environment in the upper reaches of Minjiang River. The history is divided into 4 periods, each with its own feature. During the period of nomad immigration, the top-line of the subalpine forest was forced downward by the expanding subalpine meadow. During the period of farming nationality immigration, the bottom-line of middle mountain forest had moved upward forced by the needs for land or timber of the increasing population in the valley basia During the period of the early exploiting, the focus resource was the timber. The total output was limited, comparing with the later period, because of the bad accessibility. But it was large enough to impact the forest ecosystem of the deforesting area. The recent 50 years is the crucial period of economic development and eco-environment degradation. This paper points out that the impact of human being's activities for environment lies on 3 factors: 1) physical features control the location and tendency eco-environmental change; 2) population and productivity control the scale and speed of eco-environmental change; 3) regional accessibility controls the time and location of eco-environmental change.展开更多
Twenty-six sequences of grades of dryness/wetness and a combined sequence of indexes of winter temperature since A.D. 1471 in China were adopted as our data. The fluctuations of variability of precipitation and mean t...Twenty-six sequences of grades of dryness/wetness and a combined sequence of indexes of winter temperature since A.D. 1471 in China were adopted as our data. The fluctuations of variability of precipitation and mean temperature are statistically significant from analyses. It has been found that in middle latitudes of eastern China the distribution of the relation between mean temperature and interannual variability of precipitation in historical time forms a rather complex regional pattern, and the correlation coefficients are not unique in signs. But the negative correlations are dominant either in extent or in magnitude. The authors provide evidence that Little Ice Age was a time of more frequent extremes and support the idea that the climatic instability is above normal in cool periods.展开更多
Studies of the law and characteristics of population and land-use development of the Bejing-Tianjin-Tangshen region from 1153-1949 indicated that the land development process in the region is closely related with popu...Studies of the law and characteristics of population and land-use development of the Bejing-Tianjin-Tangshen region from 1153-1949 indicated that the land development process in the region is closely related with population change of the corresponding period In Jin Dynasty, population increased rapidly, in Yuan and Ming dynasties, population increased with a sustainability while from Qing Dynasty to the founding of the Republic, population increased substatially.Wasteland reclamation and cereals cultivation by garrison and farmers appeared in Jin Dyasty and reached climax in Ming Dynasty. Correlation analysis of poulation increase and cultivated area showed that they follow a linear equation which means that population increase and cultivated area expansion were at a similar rate.展开更多
The spatially explicit reconstruction of historical land-cover datasets plays an important role in studying the climatic and ecological effects of land-use and land-cover change(LUCC). Using potential natural vegeta...The spatially explicit reconstruction of historical land-cover datasets plays an important role in studying the climatic and ecological effects of land-use and land-cover change(LUCC). Using potential natural vegetation(PNV) and satellite-based land use data, we determined the possible maximum distribution extent of forest cover in the absence of human disturbance. Subsequently, topography and climate factors were selected to assess the suitability of land for cultivation. Finally, a historical forest area allocation model was devised on the basis of the suitability of land for cultivation. As a case study, we used the historical forest area allocation model to reconstruct forest cover for 1780 and 1940 in Northeast China with a 10-km resolution. To validate the model, we compared satellite-based forest cover data with our reconstruction for 2000. A one-sample t-test of absolute bias showed that the two-tailed significance was 0.12, larger than the significant level 0.05, suggesting that the model has strong ability to capture the spatial distribution of forests. In addition, we calculated the relative difference of our reconstruction at the county scale for 1780 in Northeast China. The number of counties whose relative difference ranged from-30% to 30% is 99, accounting for 74.44% of all counties. These findings demonstrated that the provincial forest area could be transformed into forest cover maps well using the model.展开更多
The rise and fall of ancient cultures and civilizations is a hotly debated topic that has generated disagreements and disputes. In this paper we summarize some case studies on the abandonment of ancient sites, the pro...The rise and fall of ancient cultures and civilizations is a hotly debated topic that has generated disagreements and disputes. In this paper we summarize some case studies on the abandonment of ancient sites, the prosperity and collapse of ancient cultures, and demographic changes, as well as the influence of environment and technology during the prehistoric and historic periods. We then suggest that the dominant influencing factors for the evolution of ancient societies vary by spatial scale.At the local scale, sudden disasters are critical factors leading to the destruction and abandonment of large settlements. On a regional scale, climatic variations(e.g., droughts or cold events lasting for decades or centuries) are important factors that induce the collapse of ancient civilizations and mass migrations, while an enduring and stable optimal climate facilitated the prosperity of ancient civilizations. On a global scale, major technological innovations and their dispersion lasting for centuries and even millennia are major catalysts for population growth and social development. Lastly, we illustrate a possible mechanism under which environmental and technological factors played a critical role in ancient human survival and social evolution on different spatial scales.展开更多
Based on historical documents and records this paper analyzes the characteristics of frequency and distribution of major disasters that took place in the history of China. The findings show that occurrences of differe...Based on historical documents and records this paper analyzes the characteristics of frequency and distribution of major disasters that took place in the history of China. The findings show that occurrences of different types of disasters varied and spatial pattern at provincial level are significantly different as well. The results also indicate that there is a strong relationship between type of disasters and spatial distribution and that the spatial pattern of losses was not the same as that of the frequency. The reasons are: (1) the haz- ard-formative environments which, to a large extent, determine the spatial pattern of the disasters are significantly different; (2) the losses caused by natural disasters were closely related to the concentration of economy and population. Number of deaths was usually large in areas where agriculture, culture and business were relatively developed. The spatial pattern of disaster losses is an evitable result of uneven economic development in the history of China.展开更多
Using modern census and environmental factor data,this study first identified the environmental factors that significantly affect the population distribution through Geodetector analysis and then constructed a populat...Using modern census and environmental factor data,this study first identified the environmental factors that significantly affect the population distribution through Geodetector analysis and then constructed a population spatial distribution model based on the random forest regression algorithm.Finally,with this model and historical population data that were examined and corrected by historians,gridded population distributions with a spatial resolution of 10 km by 10 km in the traditional cultivated region of China(TCRC,hereafter)were reconstructed for six time slices from 1776 to 1953.Using the reconstruction dataset,the spatiotemporal characteristics of the population distribution were depicted.The results showed that(1)the environmental factors that significantly affected the population density differences among counties in the TCRC mainly consisted of elevation,slope,relief amplitude,distances to the nearest prefectural and provincial capitals,distance to the nearest river and the climatology moisture index.(2)Using the census data of 1934 counties in the TCRC in 2000 and the abovementioned environmental factor data,a random forest regression algorithm-based population spatial distribution model was constructed.Its determination coefficient(R^(2))is 0.81.In 88.4%of the counties(districts),the relative errors of the model predictions were less than 50%.(3)From 1776 to 1953,the total population in the study area showed an uptrend.Prior to 1851,the population increased mainly in the Yangtze River Delta.During this period,the number of grid cells in which the population densities were greater than 500 persons per km^(2) increased from 292 to 683.From 1851 to 1953,the population increased extensively across the study area.In the North China Plain and the Pearl River Delta,the number of grid cells in which the population densities were greater than 500 persons per km^(2) increased from 36 to 88 and from 4 to 35,respectively.The spatial clustering pattern of the population distribution varied temporally.The potential reasons included the shifts in economic development hot spots,traditional beliefs,wars,famine,and immigration policies.(4)Between our reconstructions and the HYDE dataset,there are large differences in the data sources,selected environmental factors and modeling methods.As a consequence,in comparison to our reconstructions,there were fewer populations in the eastern area and more populations in the western area from 1776 to 1851 and more populations in urban areas and fewer populations in rural areas after 1851 in the HYDE dataset.展开更多
文摘Recently, when evaluating the achievements China has made during the his- torical periods before and after reform and opening-up, Chinese President Xi Jinping pointed out, "The socialist construction conducted by the people under the leadership of our Party is divided into two historical periods--before and after reform and opening-up. The two periods are in- terconnected, but also different from each other. However, they both essen- tially reflect the practical explorations of socialist construction conducted by the people under the leadership of the Party. Socialism with Chinese characteristics began to take shape in the new era of reform and opening- up, but it is also grounded in New China's 20-plus years of experience in building and carrying out the basic system of socialism... Although the two historical periods have huge dif- ferences in the guidelines, policies,
基金supported by The Second Tibetan Plateau Scientific Expedition and Research (STEP) program(Grant No. 2019QZKK0102)the National Natural Science Foundation of China (Grant No. 41975135)+1 种基金the Natural Science Foundation of Sichuan,China (Grant No. 2022NSFSC1092)funded by the China Scholarship Council。
文摘The diurnal temperature range(DTR) serves as a vital indicator reflecting both natural climate variability and anthropogenic climate change. This study investigates the historical and projected multitemporal DTR variations over the Tibetan Plateau. It assesses 23 climate models from phase 6 of the Coupled Model Intercomparison Project(CMIP6) using CN05.1 observational data as validation, evaluating their ability to simulate DTR over the Tibetan Plateau. Then, the evolution of DTR over the Tibetan Plateau under different shared socioeconomic pathway(SSP) scenarios for the near,middle, and long term of future projection are analyzed using 11 selected robustly performing models. Key findings reveal:(1) Among the models examined, BCC-CSM2-MR, EC-Earth3, EC-Earth3-CC, EC-Earth3-Veg, EC-Earth3-Veg-LR,FGOALS-g3, FIO-ESM-2-0, GFDL-ESM4, MPI-ESM1-2-HR, MPI-ESM1-2-LR, and INM-CM5-0 exhibit superior integrated simulation capability for capturing the spatiotemporal variability of DTR over the Tibetan Plateau.(2) Projection indicates a slightly increasing trend in DTR on the Tibetan Plateau in the SSP1-2.6 scenario, and decreasing trends in the SSP2-4.5, SSP3-7.0, and SPP5-8.5 scenarios. In certain areas, such as the southeastern edge of the Tibetan Plateau, western hinterland of the Tibetan Plateau, southern Kunlun, and the Qaidam basins, the changes in DTR are relatively large.(3) Notably, the warming rate of maximum temperature under SSP2-4.5, SSP3-7.0, and SPP5-8.5 is slower compared to that of minimum temperature, and it emerges as the primary contributor to the projected decrease in DTR over the Tibetan Plateau in the future.
基金Under the auspices of National Natural Science Foundation of China(No.41471156,41501207)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA05080102)Special Fund of National Science and Technology of China(No.2014FY130500)
文摘The spatial resolution of source data, the impact factor selection on the grid model and the size of the grid might be the main limitations of global land datasets applied on a regional scale. Quantitative studies of the impacts of rasterization on data accuracy can help improve data resolution and regional data accuracy. Through a case study of cropland data for Jiangsu and Anhui provinces in China, this research compared data accuracy with different data sources, rasterization methods, and grid sizes. First, we investigated the influence of different data sources on gridded data accuracy. The temporal trends of the History Database of the Global Environment (HYDE), Chinese Historical Cropland Data (CHCD), and Suwan Cropland Data (SWCD) datasets were more similar. However, differ- ent spatial resolutions of cropland source data in the CHCD and SWCD datasets revealed an average difference of 16.61% when provin- cial and county data were downscaled to a 10 x 10 km2 grid for comparison. Second, the influence of selection of the potential arable land reclamation rate and temperature factors, as well as the different processing methods for water factors, on accuracy of gridded datasets was investigated. Applying the reclamation rate of potential cropland to grid-processing increased the diversity of spatial distri- bution but resulted in only a slightly greater standard deviation, which increased by 4.05. Temperature factors only produced relative disparities within 10% and absolute disparities within 2 km2 over more than 90% of grid cells. For the different processing methods for water factors, the HYDE dataset distributed 70% more cropland in grid cells along riverbanks, at the abandoned Yellow River Estuary (located in Binhai County, Yancheng City, Jiangsu Province), and around Hongze Lake, than did the SWCD dataset. Finally, we ex- plored the influence of different grid sizes. Absolute accuracy disparities by unit area for the year 2000 were within 0.1 km2 at a 1 km2 grid size, a 25% improvement over the 10 km2 grid size. Compared to the outcomes of other similar studies, this demonstrates that some model hypotheses and grid-processing methods in international land datasets are truly incongruent with actual land reclamation proc- esses, at least in China. Combining the model-based methods with historical empirical data may be a better way to improve the accuracy of regional scale datasets. Exploring methods for the above aspects improved the accuracy of historical crop/and gridded datasets for finer regional scales.
基金supported by the National Natural Science Foundation of China(42071313,41671353,U1303285,41571363,41431174,61471358,41201346,41301394,41301464)。
文摘Lop Sea,located at the east end of the Tarim Basin,Northwest China,dried up permanently,which is the terminal lake of the Tarim River.Lop Sea was considered as the lake basin of Lop Nor since Quaternary.However,the possibility that Lop Nor was away from the Lop Sea in historical time is crucial to be discussed to interpret the proxy records in sediment profiles.To obtain a general view of the evolution of Lop Nor and Lop Sea in a historical period,several approaches were adopted in this paper.First,the Qianlong Thirteen-Row Atlas,an ancient imperial atlas of the Qing Dynasty,which was completed around 1760,indicated that the Tarim River formed a relatively large lake at its modern upstream region.Second,a Digital Elevation Model(DEM)with a 10-m spatial resolution and a relative precision of 0.42 m was derived from TanDEM-X/Terra SAR-X satellite image pairs using the interferometry method,which was verified using ICESat-GLAS laser footprints and a local DEM acquired by a drone.Finally,based on the spatial analysis of historical documents,expedition reports,sediment profiles and archaeological evidence,it can be deduced that the lacustrine deposition was discontinued in the Lop Sea.Six episodes in the evolutionary history of the drainage system in eastern Tarim Basin were summarized.The proved depositional condition variations could be used for future interpretation of proxy records in sediment.The high-accurate DEM provided a reference for the location of further fieldwork in the Lop Sea.The method proposed in this paper may be efficient for the research of inland lakes or rivers in global arid regions.
基金National Science and Technology Pillar Program, No.2012BAH48F01 Chinese Academy of Sciences Visiting Professorship for Senior International Scientists, No.2013T2Z0004+1 种基金 National Natural Science Foundation of China, No.41171165 No.41301204
文摘This study applies ArcGIS to analyze the spatiotemporal distribution of cultural sites in the Ill River Valley in northwestern China. It explores relationships between the sites' spatiotemporal evolutionary characteristics, human history, and the natural environment. The results indicate that the numbers and proportions of the sites, and the frequency of their oc- currence, exhibited an inverted V-shaped change trend during six historical periods. The "high in the east and low in the west" spatial distribution pattern of the first three periods shifted to the one the "high in the west and low in the east" during the latter three periods, demonstrating a change in the spatial center of gravity of human activities. The sites were mainly distributed on slopes of grades 1-5, with their proportions increasing from 75% during the Spring and Autumn Period (770 BC-476 BC)-Qin Dynasty (221 BC-207 BC) to 93.75% during the Qing Dynasty-Modern period. The concentrated distribution of site elevations shifted from grades 4-8 during the Spring and Autumn Period-Qin Dynasty, and the Western Han (206 BC-8)-Southern and Northern Dynasties (420-589), to grades 1-4 during the latter three periods. The number of sites showed a shifting trend from high-elevation mountains and hills to low-elevation plains, and from high slopes to low slopes. In particular, the sites exhibited a special "moist" evolutionary pattern of migration from middle and upstream areas to downstream areas, as opposed to the migration pattern of sites located in typical arid areas. The study also considered factors influencing the distribution and spatiotemporal evolution of cultural sites, notably, human factors and natural factors.
基金This study was supported by the National key R&D Program of China(Grant 2018YFA0606402)the Strategic Priority Research Program of Chinese Academy of Sciences,Pan-Third Pole,Environment Study for a Green Silk Road(Pan-TPE)(grant no.XDA20040101)+2 种基金the second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.SQ2019QZKK2201)the Improvement on Competitiveness in Hiring New Faculties Funding Scheme(4930900)Direct Grant for Research 2018/19(4052199)of the Chinese University of Hong Kong.
文摘Social responses to climate change over human history have been widely discussed in academia over the last two decades. However, the transformation of the human–environment nexus crossing prehistoric and historic periods and the processes associated with it are not yet clearly understood. In this study, based on published works on radiocarbon dating, archaeobotany, zooarchaeology, and archaeological sites, together with a synthesis of historical documents and highresolution paleoclimatic records, we trace the extent to which human settlement patterns in the Hexi Corridor in northwestern China evolved in conjunction with climate change over the last 5,000 years. A total of 129 Neolithic, 126 Bronze Age, and 1,378 historical sites in the Hexi Corridor(n=1,633) were surveyed. Our results show that, in the Late Neolithic and Bronze Age periods(~2800–100 BC), climate change contributed to the transformation of subsistence strategies and the subsequent changes in human settlement patterns in the Hexi Corridor. The warm-humid climate in ~2800–2000 BC promoted millet agriculture and helped the Majiayao, Banshan, and Machang Cultures to flourish. The cold-dry climate in ~2000–100 BC resulted in the divergence and transformation of subsistence strategies in the Xichengyi–Qijia–Siba and Shajing–Shanma Cultures and in a shift in their settlement patterns. However, in the historical period(121 BC–AD 1911), human settlement patterns were primarily determined by geopolitics related to the alternating rule of regimes and frequent wars, especially in the Sui–Tang dynasties. We also find that trans-Eurasian cultural exchange since ~2000 BC improved social resilience to climate change in the Hexi Corridor, mediating the human–environment nexus there. Our findings may provide insights into how human societies reacted to climate change in arid and semi-arid environments over the long term.
基金Supported by the Knowledge Innovative program of Chinese Academy of Sciences(KSCX1-07-03)
文摘This paper focuses on the historical transition of human being's activities and the eco-environment in the upper reaches of Minjiang River. The history is divided into 4 periods, each with its own feature. During the period of nomad immigration, the top-line of the subalpine forest was forced downward by the expanding subalpine meadow. During the period of farming nationality immigration, the bottom-line of middle mountain forest had moved upward forced by the needs for land or timber of the increasing population in the valley basia During the period of the early exploiting, the focus resource was the timber. The total output was limited, comparing with the later period, because of the bad accessibility. But it was large enough to impact the forest ecosystem of the deforesting area. The recent 50 years is the crucial period of economic development and eco-environment degradation. This paper points out that the impact of human being's activities for environment lies on 3 factors: 1) physical features control the location and tendency eco-environmental change; 2) population and productivity control the scale and speed of eco-environmental change; 3) regional accessibility controls the time and location of eco-environmental change.
文摘Twenty-six sequences of grades of dryness/wetness and a combined sequence of indexes of winter temperature since A.D. 1471 in China were adopted as our data. The fluctuations of variability of precipitation and mean temperature are statistically significant from analyses. It has been found that in middle latitudes of eastern China the distribution of the relation between mean temperature and interannual variability of precipitation in historical time forms a rather complex regional pattern, and the correlation coefficients are not unique in signs. But the negative correlations are dominant either in extent or in magnitude. The authors provide evidence that Little Ice Age was a time of more frequent extremes and support the idea that the climatic instability is above normal in cool periods.
文摘Studies of the law and characteristics of population and land-use development of the Bejing-Tianjin-Tangshen region from 1153-1949 indicated that the land development process in the region is closely related with population change of the corresponding period In Jin Dynasty, population increased rapidly, in Yuan and Ming dynasties, population increased with a sustainability while from Qing Dynasty to the founding of the Republic, population increased substatially.Wasteland reclamation and cereals cultivation by garrison and farmers appeared in Jin Dyasty and reached climax in Ming Dynasty. Correlation analysis of poulation increase and cultivated area showed that they follow a linear equation which means that population increase and cultivated area expansion were at a similar rate.
基金China Global Change Research Program,No.2010CB950901 National Natural Science Foundation of China,No.41271227
文摘The spatially explicit reconstruction of historical land-cover datasets plays an important role in studying the climatic and ecological effects of land-use and land-cover change(LUCC). Using potential natural vegetation(PNV) and satellite-based land use data, we determined the possible maximum distribution extent of forest cover in the absence of human disturbance. Subsequently, topography and climate factors were selected to assess the suitability of land for cultivation. Finally, a historical forest area allocation model was devised on the basis of the suitability of land for cultivation. As a case study, we used the historical forest area allocation model to reconstruct forest cover for 1780 and 1940 in Northeast China with a 10-km resolution. To validate the model, we compared satellite-based forest cover data with our reconstruction for 2000. A one-sample t-test of absolute bias showed that the two-tailed significance was 0.12, larger than the significant level 0.05, suggesting that the model has strong ability to capture the spatial distribution of forests. In addition, we calculated the relative difference of our reconstruction at the county scale for 1780 in Northeast China. The number of counties whose relative difference ranged from-30% to 30% is 99, accounting for 74.44% of all counties. These findings demonstrated that the provincial forest area could be transformed into forest cover maps well using the model.
基金supported by the National Natural Science Foundation of China(Grant Nos.41620104007 and 41671077)the Fundamental Research Funds for the Central Universities(Grant No.LZUJBKY-2015-k09)
文摘The rise and fall of ancient cultures and civilizations is a hotly debated topic that has generated disagreements and disputes. In this paper we summarize some case studies on the abandonment of ancient sites, the prosperity and collapse of ancient cultures, and demographic changes, as well as the influence of environment and technology during the prehistoric and historic periods. We then suggest that the dominant influencing factors for the evolution of ancient societies vary by spatial scale.At the local scale, sudden disasters are critical factors leading to the destruction and abandonment of large settlements. On a regional scale, climatic variations(e.g., droughts or cold events lasting for decades or centuries) are important factors that induce the collapse of ancient civilizations and mass migrations, while an enduring and stable optimal climate facilitated the prosperity of ancient civilizations. On a global scale, major technological innovations and their dispersion lasting for centuries and even millennia are major catalysts for population growth and social development. Lastly, we illustrate a possible mechanism under which environmental and technological factors played a critical role in ancient human survival and social evolution on different spatial scales.
基金National Technology R&D Program,No.2008BAK50B05Knowledge Innovation Program of the Chinese Academy of Sciences,No.KZCXZ-YW-Q03-08
文摘Based on historical documents and records this paper analyzes the characteristics of frequency and distribution of major disasters that took place in the history of China. The findings show that occurrences of different types of disasters varied and spatial pattern at provincial level are significantly different as well. The results also indicate that there is a strong relationship between type of disasters and spatial distribution and that the spatial pattern of losses was not the same as that of the frequency. The reasons are: (1) the haz- ard-formative environments which, to a large extent, determine the spatial pattern of the disasters are significantly different; (2) the losses caused by natural disasters were closely related to the concentration of economy and population. Number of deaths was usually large in areas where agriculture, culture and business were relatively developed. The spatial pattern of disaster losses is an evitable result of uneven economic development in the history of China.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA19040101)the National Key Research and Development Program of China(Grant No.2017YFA0603301).
文摘Using modern census and environmental factor data,this study first identified the environmental factors that significantly affect the population distribution through Geodetector analysis and then constructed a population spatial distribution model based on the random forest regression algorithm.Finally,with this model and historical population data that were examined and corrected by historians,gridded population distributions with a spatial resolution of 10 km by 10 km in the traditional cultivated region of China(TCRC,hereafter)were reconstructed for six time slices from 1776 to 1953.Using the reconstruction dataset,the spatiotemporal characteristics of the population distribution were depicted.The results showed that(1)the environmental factors that significantly affected the population density differences among counties in the TCRC mainly consisted of elevation,slope,relief amplitude,distances to the nearest prefectural and provincial capitals,distance to the nearest river and the climatology moisture index.(2)Using the census data of 1934 counties in the TCRC in 2000 and the abovementioned environmental factor data,a random forest regression algorithm-based population spatial distribution model was constructed.Its determination coefficient(R^(2))is 0.81.In 88.4%of the counties(districts),the relative errors of the model predictions were less than 50%.(3)From 1776 to 1953,the total population in the study area showed an uptrend.Prior to 1851,the population increased mainly in the Yangtze River Delta.During this period,the number of grid cells in which the population densities were greater than 500 persons per km^(2) increased from 292 to 683.From 1851 to 1953,the population increased extensively across the study area.In the North China Plain and the Pearl River Delta,the number of grid cells in which the population densities were greater than 500 persons per km^(2) increased from 36 to 88 and from 4 to 35,respectively.The spatial clustering pattern of the population distribution varied temporally.The potential reasons included the shifts in economic development hot spots,traditional beliefs,wars,famine,and immigration policies.(4)Between our reconstructions and the HYDE dataset,there are large differences in the data sources,selected environmental factors and modeling methods.As a consequence,in comparison to our reconstructions,there were fewer populations in the eastern area and more populations in the western area from 1776 to 1851 and more populations in urban areas and fewer populations in rural areas after 1851 in the HYDE dataset.