Knowledge of the interactions among atmospheric dynamics,dust emissions and climate system is essential to understand the physical mechanisms for the dust lifecycle,their role in loess formation as well as the predict...Knowledge of the interactions among atmospheric dynamics,dust emissions and climate system is essential to understand the physical mechanisms for the dust lifecycle,their role in loess formation as well as the predictions of future dust concentration.However,these issues still remain relatively poorly known in Central Asia(CA).The extensive loess deposits on the CA pediments provide a promising archive to explore atmospheric dust dynamics and climatic conditions in the past and their association with loess formation.This study investigates the granulometric and magnetic properties of a loess section(named Osh section)in the Fergana Valley,which provides a sensitive record of atmospheric dust dynamics since 30 ka based on radiometric(AMS ^(14)C)dating.The frequency-dependent magnetic susceptibility(χfd)and the mean grain size are used to reconstruct the broadscale effective moisture and summer atmospheric dynamics pattern in CA,respectively.The results show that the precession forcing exerts a huge influence on the wind-regime variabilities in CA,but with different physical processes under the impact of the Northern Hemisphere ice sheet(NHIS)before and after 15 ka.The origin of the sedimentation rate variations in the Osh loess is also linked to the NHIS-modulated changes of the atmospheric circulation patterns.Either the strengthened westerlies or the increased surface roughness from higher vegetation cover in loess-deposition areas have significantly accelerated the loess accumulation.As a result,these complicated influence factors of sedimentation rate change in the Osh loess section,especially during the Holocene epoch,may hamper accessibility of the authentic dust emission flux and atmospheric dust concentration in CA.展开更多
Characterization of transport pathways and depositional changes in Mercury(Hg)and their connection to climatic and environmental changes on various time scales are crucial for better understanding the anthropogenic im...Characterization of transport pathways and depositional changes in Mercury(Hg)and their connection to climatic and environmental changes on various time scales are crucial for better understanding the anthropogenic impacts on the global Hg cycle in the Anthropocene epoch.In this study,we examined Hg variations recorded in a stalagmite from central China,covering the period from 25.5 to 10.9 thousand years ago.Our data show a marked increase in Hg concentrations during the late Last Glacial Maximum,which coincided with the period of highest dust deposition on the Chinese Loess Plateau.Hg concentrations were lower during Heinrich events 1 and 2 and the Younger Dryas but higher during the BùllingAllerùd and the early Holocene.We suggest that regional dust load,which enhances atmospheric dry deposition of Hg,is the primary factor influencing Hg deposition in central China on glacialinterglacial timescales.On millennial-to-centennial timescales,climate also plays a significant role.Warmer and wetter conditions increase vegetation,litterfall,and soil/rock weathering,which in turn boost mineral dissolution and soil erosion in the vadose zone.These processes collectively result in higher Hg concentrations in the stalagmite.展开更多
The current and potential impacts of global warming have generated widespread concerns about food security among all sectors of society.Central Asian countries located deep in the interior of Asia with fragile ecologi...The current and potential impacts of global warming have generated widespread concerns about food security among all sectors of society.Central Asian countries located deep in the interior of Asia with fragile ecological environments and lower agricultural technology are particularly more prone to severe threats from climate change.Based on panel data acquired in five Central Asian countries from 1990 to 2019,a C-D-C model was developed to study how climate change affects food security in the region and to predict future trends.The study found that the level of food security has generally increased for these five Central Asian countries over the past 30 years,with Kazakhstan and Tajikistan having the highest and lowest food security levels,respectively.The average annual temperature and precipitation exhibit an inverted U-shaped relationship with the region’s food security,with the most positive effect on the food security of Kazakhstan.Extremely high and low temperatures have significantly affected food security in the studied region,with Turkmenistan experiencing the most significant negative impacts.The number of frost days had no significant effect on food security.An analysis of future climate showed that the temperature and precipitation in Central Asia will continue to increase from 2030 to 2090,which will negatively impact the food security of these countries.It is recommended that the Central Asian countries enhance their understanding of climate risks,strengthen scientific climate research,and develop multiple adaptation strategies in advance.Simultaneously,they are encouraged to consolidate international cooperation,reducing greenhouse gas emissions effectively and maintaining the ability to ensure food security.展开更多
2004年上映了福克斯公司制作的科幻片《后天》(The Day After Tomorrow),主要讲述温室效应造成大洋环流异动、地球重新来到冰河纪的故事.近年来不断有证据表明,大洋环流在全球变暖背景下已经进入了一个显著变弱的阶段[1].预测这种环流...2004年上映了福克斯公司制作的科幻片《后天》(The Day After Tomorrow),主要讲述温室效应造成大洋环流异动、地球重新来到冰河纪的故事.近年来不断有证据表明,大洋环流在全球变暖背景下已经进入了一个显著变弱的阶段[1].预测这种环流减弱是否如“后天”猜测的那般,需要对过去大洋环流的变化进行重建.展开更多
Recently,Wu et al.[1]suggested an earthquake-induced landslide dam outburst flood on the eastern Tibetan Plateau at 1920BCE(3870 a BP,BP denotes year before 1950 CE)caused the Great Flood in the middle-lower Yellow Ri...Recently,Wu et al.[1]suggested an earthquake-induced landslide dam outburst flood on the eastern Tibetan Plateau at 1920BCE(3870 a BP,BP denotes year before 1950 CE)caused the Great Flood in the middle-lower Yellow River reaches,and resulted in the founding of Xia Dynasty at 3850 a BP.This age is$150–300younger than the previously estimated age of the Xia Dynasty[2].While the geological evidence of the outburst flood。展开更多
Arid Central Asia(ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean.Ecological p...Arid Central Asia(ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean.Ecological pockets and ecoclines in ACA are largely determined by local precipitation. However, little research has gone into the effects of hydroclimatic changes on trans-Eurasian cultural exchange. Here,we reconstruct precipitation changes in ACA, covering the mid-late Holocene with a U-Th dated, ~3 a resolution, multi-proxy time series of replicated stalagmites from the southeastern Fergana Valley,Kyrgyzstan. Our data reveal a 640-a megadrought between 5820 and 5180 a BP, which likely impacted cultural development in ACA and impeded the expansion of cultural traits along oasis routes. Instead,it may have diverted the earliest transcontinental exchange along the Eurasian steppe during the 5 th millennium BP. With gradually increasing precipitation after the megadrought, settlement of peoples in the oases and river valleys may have facilitated the opening of the oasis routes, ‘‘prehistoric Silk Roads", of trans-Eurasian exchange. By the 4 th millennium BP, this process may have reshaped cultures across the two continents, laying the foundation for the organized Silk Roads.展开更多
Application of X-ray fluorescence core-scanning(XRF-CS) on both marine and lake sediments has achieved remarkable results. However, its application has not been widely extended to the research on speleothems. In this ...Application of X-ray fluorescence core-scanning(XRF-CS) on both marine and lake sediments has achieved remarkable results. However, its application has not been widely extended to the research on speleothems. In this study, we measure the Sr abundance and the Sr/Ca ratios of three stalagmites(two aragonite stalagmites, one calcite stalagmite) using the state-of-the-art fourth-generation Avaatech high-resolution XRF core scanner. Through comparisons among different scan paths and among different scan resolutions, as well as comparisons with inductively coupled plasma optical emission spectrometer(ICP-OES), Itrax XRF, and Artax XRF results, we confirm that the Avaatech XRF core scanner could precisely, quickly, and nondestructively analyze the high-resolution Sr abundance of speleothems. Furthermore, we combine the stalagmite δ^(18)O records to explore the paleoclimatic significance of the measured stalagmite Sr/Ca.展开更多
Hydroclimatic variations over the eastern Central Asia are highly sensitive to changes in hemispheric-scale atmospheric circulation systems. To fully understand the long-term variability and relationship between hydro...Hydroclimatic variations over the eastern Central Asia are highly sensitive to changes in hemispheric-scale atmospheric circulation systems. To fully understand the long-term variability and relationship between hydroclimate and atmospheric circulation system, we present a high-resolution lascustrine record of late Holocene hydroclimate from Lake Sayram, Central Tianshan Mountains, China, based on the total organic carbon, total nitrogen, and carbonate contents, carbon/nitrogen ratios, and grain size. Our results reveal four periods of substantially increased precipitation at the interval of 4000–3780, 3590–3210, 2800–2160, and 890–280 cal yr BP, and one period of slightly increased precipitation from 1700–1370 cal yr BP. These wetter periods broadly coincide with those identified in other records from the mid-latitude Westerlies-dominated eastern Central Asia, including the northern Tibetan Plateau. As such, a similar hydroclimatic pattern existed over this entire region during the late Holocene. Based on a close similarity of our record with reconstruction of North Atlantic Oscillation indices and solar irradiance, we propose that decreased solar irradiance and southern migration of the entire circum-North Atlantic circulation system, particularly the main pathway of the mid-latitude Westerlies, significantly influenced hydroclimate in eastern Central Asia during the late Holocene. Finally, the inferred precipitation at Lake Sayram has increased markedly over the past 100 years, although this potential future changes in hydroclimate in Central Asia need for further investigation.展开更多
Since Homo sapiens appeared,the planet has experienced continuing environmental changes[1,2].In 2000,Crutzen and Stoermer[3]systematically analysed the global changes caused by human activity over the previous 300 yea...Since Homo sapiens appeared,the planet has experienced continuing environmental changes[1,2].In 2000,Crutzen and Stoermer[3]systematically analysed the global changes caused by human activity over the previous 300 years and suggested that the Holocene epoch ended in the 1750s and a new geological age,the Anthropocene,began.Afterwards,the Anthropocene drew a lot of attention from both scientific community and the general public.The recognition and placement of the Anthropocene/Holocene boundary has been a subject of heated debates over the past two decades.At the 35th International Geological Congress(2016;IGC),the Anthropocene Working Group(AWG)recommended the Anthropocene to be formalised with an epoch rank,with the 1950s as its lower boundary[4].展开更多
The history and mechanisms of dust storms in northern China remain unclear owing to the paucity of reliable longterm,high-resolution geological records.In this study,we reconstructed the dust storm history of the last...The history and mechanisms of dust storms in northern China remain unclear owing to the paucity of reliable longterm,high-resolution geological records.In this study,we reconstructed the dust storm history of the last~500 years in northern China,based on sedimentary coarse fraction(>63μm)of a well-dated core from Lake Daihai,Inner Mongolia.The highresolution data reveal three intervals of frequent dust storms:AD 1520–1580,AD 1610–1720,and AD 1870–2000.The dust storm events in the Lake Daihai area were broadly synchronous with those inferred from other historical or geological records and generally occurred during cold intervals.Changes in the intensity of Siberian High and the westerlies modulated by temperature variations are the likely major factors controlling dust storm dynamics.An interesting feature is that although the intensities of dust storms have been systematically increased during the recent warming period,a clear decreasing trend within this period is evident.The recent increase in average dust storm intensity may be ascribed to an increase in particle supply resulting from a rapid increase in human activity,whereas the weakening trend was likely caused by decreases in average wind speed resulting from the recent global warming.展开更多
Evaluating anthropogenic impacts on regional vegetation changes during historical time is not only important for a better understanding of the Anthropocene but also valuable in improving the vegetation-climate models....Evaluating anthropogenic impacts on regional vegetation changes during historical time is not only important for a better understanding of the Anthropocene but also valuable in improving the vegetation-climate models.In this study,we analyzed stable isotopes(δ^18O,δ^13C)and trace elements(Mg/Ca,Sr/Ca)of a stalagmite from Huangchao Cave in central Shandong,northern China.230Th and AMS14C dating results indicate the stalagmite deposited during 174BC and AD1810,with a hiatus between AD638 and 1102.Broad similarities of theδ^18O and trace elements in the stalagmite suggest they are reliable precipitation indexes.Theδ^13C of the stalagmite,a proxy of vegetation change,was generally consistent with local precipitation and temperature variations on a centennial-scale before the 15th century.It typically varied from–9.6‰to–6.3‰,indicating climate controlled C3 type vegetation during this period.However,a persistent and marked increasing trend in theδ^13C record was observed since the 15th century,resulting inδ^13C values from–7.7‰to–1.6‰in the next four centuries.This unprecedentedδ^13C change caused by vegetation deterioration cannot be explained by climate change but is fairly consistent with the dramatically increasing population and farmland in Shandong.We suggest that the increasing deforestation and reclamation in central Shandong began to affect vegetation in the mountain region of central Shandong since the 15th century and severely destroyed or even cleared the forest during the 16th–18th century.展开更多
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(Grant Nos.XDB40000000 and XDB26000000)Natural Science Foundation of China(Grant Nos.41977385 and 41572162)+1 种基金Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0101)State Key Laboratory of Loess and Quaternary Geology(Grant No.SKLLQGPY2006).
文摘Knowledge of the interactions among atmospheric dynamics,dust emissions and climate system is essential to understand the physical mechanisms for the dust lifecycle,their role in loess formation as well as the predictions of future dust concentration.However,these issues still remain relatively poorly known in Central Asia(CA).The extensive loess deposits on the CA pediments provide a promising archive to explore atmospheric dust dynamics and climatic conditions in the past and their association with loess formation.This study investigates the granulometric and magnetic properties of a loess section(named Osh section)in the Fergana Valley,which provides a sensitive record of atmospheric dust dynamics since 30 ka based on radiometric(AMS ^(14)C)dating.The frequency-dependent magnetic susceptibility(χfd)and the mean grain size are used to reconstruct the broadscale effective moisture and summer atmospheric dynamics pattern in CA,respectively.The results show that the precession forcing exerts a huge influence on the wind-regime variabilities in CA,but with different physical processes under the impact of the Northern Hemisphere ice sheet(NHIS)before and after 15 ka.The origin of the sedimentation rate variations in the Osh loess is also linked to the NHIS-modulated changes of the atmospheric circulation patterns.Either the strengthened westerlies or the increased surface roughness from higher vegetation cover in loess-deposition areas have significantly accelerated the loess accumulation.As a result,these complicated influence factors of sedimentation rate change in the Osh loess section,especially during the Holocene epoch,may hamper accessibility of the authentic dust emission flux and atmospheric dust concentration in CA.
基金supported by the National Natural Science Foundation of China(42325705 and 42230208)the Chinese Academy of Sciences(xbzg-zdsys-202217)。
文摘Characterization of transport pathways and depositional changes in Mercury(Hg)and their connection to climatic and environmental changes on various time scales are crucial for better understanding the anthropogenic impacts on the global Hg cycle in the Anthropocene epoch.In this study,we examined Hg variations recorded in a stalagmite from central China,covering the period from 25.5 to 10.9 thousand years ago.Our data show a marked increase in Hg concentrations during the late Last Glacial Maximum,which coincided with the period of highest dust deposition on the Chinese Loess Plateau.Hg concentrations were lower during Heinrich events 1 and 2 and the Younger Dryas but higher during the BùllingAllerùd and the early Holocene.We suggest that regional dust load,which enhances atmospheric dry deposition of Hg,is the primary factor influencing Hg deposition in central China on glacialinterglacial timescales.On millennial-to-centennial timescales,climate also plays a significant role.Warmer and wetter conditions increase vegetation,litterfall,and soil/rock weathering,which in turn boost mineral dissolution and soil erosion in the vadose zone.These processes collectively result in higher Hg concentrations in the stalagmite.
基金This work was supported by the Chinese Academy of Sciences(Grant No.xbzg-zdsys-202217)the Shandong Provincial Special Fund(Grant No.LSKJ202203300).
文摘The current and potential impacts of global warming have generated widespread concerns about food security among all sectors of society.Central Asian countries located deep in the interior of Asia with fragile ecological environments and lower agricultural technology are particularly more prone to severe threats from climate change.Based on panel data acquired in five Central Asian countries from 1990 to 2019,a C-D-C model was developed to study how climate change affects food security in the region and to predict future trends.The study found that the level of food security has generally increased for these five Central Asian countries over the past 30 years,with Kazakhstan and Tajikistan having the highest and lowest food security levels,respectively.The average annual temperature and precipitation exhibit an inverted U-shaped relationship with the region’s food security,with the most positive effect on the food security of Kazakhstan.Extremely high and low temperatures have significantly affected food security in the studied region,with Turkmenistan experiencing the most significant negative impacts.The number of frost days had no significant effect on food security.An analysis of future climate showed that the temperature and precipitation in Central Asia will continue to increase from 2030 to 2090,which will negatively impact the food security of these countries.It is recommended that the Central Asian countries enhance their understanding of climate risks,strengthen scientific climate research,and develop multiple adaptation strategies in advance.Simultaneously,they are encouraged to consolidate international cooperation,reducing greenhouse gas emissions effectively and maintaining the ability to ensure food security.
文摘2004年上映了福克斯公司制作的科幻片《后天》(The Day After Tomorrow),主要讲述温室效应造成大洋环流异动、地球重新来到冰河纪的故事.近年来不断有证据表明,大洋环流在全球变暖背景下已经进入了一个显著变弱的阶段[1].预测这种环流减弱是否如“后天”猜测的那般,需要对过去大洋环流的变化进行重建.
基金funded by the National Key Research and Development Program of China (2017YFA0603401)National Natural Science Foundation of China (41372192)+2 种基金Science Foundation for Distinguished Young Scholars of Shaanxi Province, ChinaYouth Innovation Promotion Association of Chinese Academy of SciencesWest Light Foundation of Chinese Academy of Sciences
文摘Recently,Wu et al.[1]suggested an earthquake-induced landslide dam outburst flood on the eastern Tibetan Plateau at 1920BCE(3870 a BP,BP denotes year before 1950 CE)caused the Great Flood in the middle-lower Yellow River reaches,and resulted in the founding of Xia Dynasty at 3850 a BP.This age is$150–300younger than the previously estimated age of the Xia Dynasty[2].While the geological evidence of the outburst flood。
基金supported by the National Key Research and Development Program of China (2018YFA0606400)he Strategic Priority Research Program of Chinese Academy of Sciences (XDB40000000)+5 种基金the 2nd Tibetan Plateau Scientific Expedition and Research (2019QZKK0101)the Youth Innovation Promotion Association of Chinese Academy of Sciences (Y201681)partly supported by the National Natural Science Foundation of China (41888101)the National Social Science Foundation of China (18ZDA172)the National Science Foundation of United States (NSF 1702816, EAR-0908792, and EAR-1211299)a part of the ‘‘Belt & Road” Project of the Institute of Earth Environment, Chinese Academy of Sciences (IEECAS)。
文摘Arid Central Asia(ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean.Ecological pockets and ecoclines in ACA are largely determined by local precipitation. However, little research has gone into the effects of hydroclimatic changes on trans-Eurasian cultural exchange. Here,we reconstruct precipitation changes in ACA, covering the mid-late Holocene with a U-Th dated, ~3 a resolution, multi-proxy time series of replicated stalagmites from the southeastern Fergana Valley,Kyrgyzstan. Our data reveal a 640-a megadrought between 5820 and 5180 a BP, which likely impacted cultural development in ACA and impeded the expansion of cultural traits along oasis routes. Instead,it may have diverted the earliest transcontinental exchange along the Eurasian steppe during the 5 th millennium BP. With gradually increasing precipitation after the megadrought, settlement of peoples in the oases and river valleys may have facilitated the opening of the oasis routes, ‘‘prehistoric Silk Roads", of trans-Eurasian exchange. By the 4 th millennium BP, this process may have reshaped cultures across the two continents, laying the foundation for the organized Silk Roads.
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFA0603401)Shaanxi Science Fund for Distinguished Young Scholars (Grant No. 2018JC-023)+2 种基金Youth Innovation Promotion Association (Grant No. 2012295)West Light Foundation of Chinese Academy of Sciencesa part of The "Belt & Road" Project of the Institute of Earth Environment, Chinese Academy of Sciences
文摘Application of X-ray fluorescence core-scanning(XRF-CS) on both marine and lake sediments has achieved remarkable results. However, its application has not been widely extended to the research on speleothems. In this study, we measure the Sr abundance and the Sr/Ca ratios of three stalagmites(two aragonite stalagmites, one calcite stalagmite) using the state-of-the-art fourth-generation Avaatech high-resolution XRF core scanner. Through comparisons among different scan paths and among different scan resolutions, as well as comparisons with inductively coupled plasma optical emission spectrometer(ICP-OES), Itrax XRF, and Artax XRF results, we confirm that the Avaatech XRF core scanner could precisely, quickly, and nondestructively analyze the high-resolution Sr abundance of speleothems. Furthermore, we combine the stalagmite δ^(18)O records to explore the paleoclimatic significance of the measured stalagmite Sr/Ca.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41672169, 41473120 & 41502171)the Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant No. 2012295)
文摘Hydroclimatic variations over the eastern Central Asia are highly sensitive to changes in hemispheric-scale atmospheric circulation systems. To fully understand the long-term variability and relationship between hydroclimate and atmospheric circulation system, we present a high-resolution lascustrine record of late Holocene hydroclimate from Lake Sayram, Central Tianshan Mountains, China, based on the total organic carbon, total nitrogen, and carbonate contents, carbon/nitrogen ratios, and grain size. Our results reveal four periods of substantially increased precipitation at the interval of 4000–3780, 3590–3210, 2800–2160, and 890–280 cal yr BP, and one period of slightly increased precipitation from 1700–1370 cal yr BP. These wetter periods broadly coincide with those identified in other records from the mid-latitude Westerlies-dominated eastern Central Asia, including the northern Tibetan Plateau. As such, a similar hydroclimatic pattern existed over this entire region during the late Holocene. Based on a close similarity of our record with reconstruction of North Atlantic Oscillation indices and solar irradiance, we propose that decreased solar irradiance and southern migration of the entire circum-North Atlantic circulation system, particularly the main pathway of the mid-latitude Westerlies, significantly influenced hydroclimate in eastern Central Asia during the late Holocene. Finally, the inferred precipitation at Lake Sayram has increased markedly over the past 100 years, although this potential future changes in hydroclimate in Central Asia need for further investigation.
基金supported by the Shaanxi Science Fund for Distinguished Young Scholars (2018JC-023)the National Natural Science Foundation of China (41842053)+1 种基金the Youth Innovation Promotion Association (2012295)International Partnership Program (132B61KYSB20170005) of Chinese Academy of Sciences
文摘Since Homo sapiens appeared,the planet has experienced continuing environmental changes[1,2].In 2000,Crutzen and Stoermer[3]systematically analysed the global changes caused by human activity over the previous 300 years and suggested that the Holocene epoch ended in the 1750s and a new geological age,the Anthropocene,began.Afterwards,the Anthropocene drew a lot of attention from both scientific community and the general public.The recognition and placement of the Anthropocene/Holocene boundary has been a subject of heated debates over the past two decades.At the 35th International Geological Congress(2016;IGC),the Anthropocene Working Group(AWG)recommended the Anthropocene to be formalised with an epoch rank,with the 1950s as its lower boundary[4].
基金supported by the National Natural Science Foundation of China(Grant No.U20A2078)the Joint NSFC-ISF Research Program(NSFC Grant No.41761144070ISF Grant No.2487/17)。
文摘The history and mechanisms of dust storms in northern China remain unclear owing to the paucity of reliable longterm,high-resolution geological records.In this study,we reconstructed the dust storm history of the last~500 years in northern China,based on sedimentary coarse fraction(>63μm)of a well-dated core from Lake Daihai,Inner Mongolia.The highresolution data reveal three intervals of frequent dust storms:AD 1520–1580,AD 1610–1720,and AD 1870–2000.The dust storm events in the Lake Daihai area were broadly synchronous with those inferred from other historical or geological records and generally occurred during cold intervals.Changes in the intensity of Siberian High and the westerlies modulated by temperature variations are the likely major factors controlling dust storm dynamics.An interesting feature is that although the intensities of dust storms have been systematically increased during the recent warming period,a clear decreasing trend within this period is evident.The recent increase in average dust storm intensity may be ascribed to an increase in particle supply resulting from a rapid increase in human activity,whereas the weakening trend was likely caused by decreases in average wind speed resulting from the recent global warming.
基金supported by the National Natural Science Foundation of China(Grant No.41991252)the Strategic Priority Research Program(Grant No.XDB40000000)+4 种基金the International Partnership Program(Grant No.132B61KYSB20170005)of Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant No.41888101)partly supported by the USA National Science Foundation(Grant Nos.0908792,1211299&1702816 to R.Lawrence EDWARDS and Hai CHENG)the 111 Program of China(Grant No.D19002)the Belt&Road Center for Climate and Environment Studies of IEECAS。
文摘Evaluating anthropogenic impacts on regional vegetation changes during historical time is not only important for a better understanding of the Anthropocene but also valuable in improving the vegetation-climate models.In this study,we analyzed stable isotopes(δ^18O,δ^13C)and trace elements(Mg/Ca,Sr/Ca)of a stalagmite from Huangchao Cave in central Shandong,northern China.230Th and AMS14C dating results indicate the stalagmite deposited during 174BC and AD1810,with a hiatus between AD638 and 1102.Broad similarities of theδ^18O and trace elements in the stalagmite suggest they are reliable precipitation indexes.Theδ^13C of the stalagmite,a proxy of vegetation change,was generally consistent with local precipitation and temperature variations on a centennial-scale before the 15th century.It typically varied from–9.6‰to–6.3‰,indicating climate controlled C3 type vegetation during this period.However,a persistent and marked increasing trend in theδ^13C record was observed since the 15th century,resulting inδ^13C values from–7.7‰to–1.6‰in the next four centuries.This unprecedentedδ^13C change caused by vegetation deterioration cannot be explained by climate change but is fairly consistent with the dramatically increasing population and farmland in Shandong.We suggest that the increasing deforestation and reclamation in central Shandong began to affect vegetation in the mountain region of central Shandong since the 15th century and severely destroyed or even cleared the forest during the 16th–18th century.
