Based on high-resolution analysis to a 280-cm long sediment core obtained from the muddy area in the central Yellow Sea, we examined the provenance of muddy sediments and discussed the changing marine sedimentary envi...Based on high-resolution analysis to a 280-cm long sediment core obtained from the muddy area in the central Yellow Sea, we examined the provenance of muddy sediments and discussed the changing marine sedimentary environment since the middle Holocene. The results indicated that fine-grained sediments in the muddy area were mainly derived from the Huanghe(Yellow River) and Changjiang(Yangtze River) with considerable stepwise variations during the past 6.6 kyr. The Yellow Sea Warm Current was initiated at 6 kyr when the sea level was high together with the enhanced East Asian Winter Monsoon. These in combination established the framework of shelf circulation in the Yellow Sea that began to trap the river-derived fine-grained sediments. From 4.9 kyr to 2.8 kyr, both the Kushiro Current and East Asian Monsoon were significantly weakened, reducing the delivery of Changjiang sediments to the muddy area. As a result, the sediments were mainly originated from the Huanghe. From 2.8 kyr to 1.5 kyr the continuously weakened East Asian Winter Monsoon and enhanced Yellow Sea Warm Current entrapped more fine-grain sediments. Whereas the enhanced East Asian Winter Monsoon and the human caused increase in sediment load of the Huanghe since 1.5 kyr, and direct delivery of Huanghe sediments to the Yellow Sea during 1128–1855 AD might dominated the sedimentation in the study area. The stepwise variations of the sediment provenance and composition of the Central Yellow Sea muddy sediments are of importance to understanding the formation of muddy deposit in the central Yellow Sea and the associated variations of marine environment since the middle Holocene.展开更多
Peatlands are some of the largest carbon reservoirs in terrestrial ecosystems and play a key role in the global carbon cycle.Understanding peatland development,carbon accumulation processes,and the peatland response t...Peatlands are some of the largest carbon reservoirs in terrestrial ecosystems and play a key role in the global carbon cycle.Understanding peatland development,carbon accumulation processes,and the peatland response to varying forcing factors over different temporal and spatial scales helps reveal the underlying processes and general patterns of these ecosystems.To assess the role of climate and local conditions in peatland development,the basal samples from 23 peat cores and three well dated long peat cores were used to explore peatland initiation,lateral expansion,and carbon accumulation rate in the Baijianghe peatland located in the Changbai Mountains,Northeast China.Our results reveal that the Baijianghe peatland was initiated from forest conditions at 7.9 cal.kyr BP and then expanded laterally by paludification.The rapid expansion between 5 and4 cal.kyr BP likely resulted from high precipitation and gentle topography.The mean carbon accumulation rates of the three long peat cores were 36.3,39.1 and 48.4 g C m^(-2)yr^(-1),respectively,which are higher than rates from the northern peatlands.Both climate and local conditions have exerted an important influence on carbon accumulation rates in the Baijianghe peatland since the middle Holocene.The carbon accumulation patterns between 5 and 1.5 cal.kyr BP were probably linked to local conditions rather than climatic settings,including topography,hydrological conditions,and plant composition.The consistently decreasing carbon accumulation rate values at all locations within the BJH peatland over the last 1.5 cal.kyr BP suggests that climate is the primary control.This study highlights the varying primary controls on the process of peatland development and reveals the important role of local conditions in carbon accumulation.展开更多
High-resolution sea-level data and high-precision dating of corals in the northern South China Sea(SCS)during the Holocene provide a reference and historical background for current and future sea-level changes and a b...High-resolution sea-level data and high-precision dating of corals in the northern South China Sea(SCS)during the Holocene provide a reference and historical background for current and future sea-level changes and a basis for scientific assessment of the evolutionary trend of coral reefs in the SCS.Although sporadic studies have been performed around Hainan Island in the northern SCS,the reconstructed sea level presents different values or is controversial because the indicative meaning of the sea-level indicators were neither quantified nor uniform criteria.Here,we determined the quantitative relationship between modern living coral and sea level by measuring the top surfaces of 27 live Porites corals from the inner reef flat along the east coast of Hainan Island and assessed the accuracy of results obtained using coral as sea-level indicators.Additionally,three in situ fossil Porites corals were analyzed based on elevation measurements,digital X-ray radiography,and U-Th dating.The survey results showed that the indicative meanings for the modern live Porites corals is(146.09±8.35)cm below the mean tide level(MTL).It suggested that their upward growth limit is constrained by the sea level,and the lowest low water is the highest level of survival for the modern live Porites corals.Based on the newly defined indicative meanings,6 new sea-level index points(SLIPs)were obtained and 19 published SLIPs were recalculated.Those SLIPs indicated a relative sea level fluctuation between(227.7±9.8)cm to(154.88±9.8)cm MTL between(5393±25)cal a BP and(3390±12)cal a BP,providing evidences of the Mid-Holocene sea-level highstand in the northern SCS.Besides that,our analysis demonstrated that different sea-level histories may be produced based on different indicative meanings or criteria.The dataset of 276 coral U-Th ages indicates that coral reef development in the northern SCS comprised the initial development,boom growth,decline,and flourishing development again.A comparison with regional records indicated that synergistic effects of climatic and environmental factors were involved in the development of coral reefs in the northern SCS.Thus,the cessation of coral reef development during the Holocene in the northern SCS was probably associated with the dry and cold climate in South China,as reflected in the synchronous weakening of the ENSO and East Asian summer monsoon induced by the reduction of the 65°N summer insolation,which forced the migration of the Intertropical Convergence Zone.展开更多
For a long time,the academic community has known very little about hunter-gatherers in the steppe area of northern China in the mid-Holocene.This article reports on the Ula Usu West site in Siziwangqi Banner,Inner Mon...For a long time,the academic community has known very little about hunter-gatherers in the steppe area of northern China in the mid-Holocene.This article reports on the Ula Usu West site in Siziwangqi Banner,Inner Mongolia,including basic information about the site,animal bones,lithic artifacts and the environmental background.The age of the site is 4.8–4.4 cal.kyr BP,placing it in the Late Neolithic period.Considering integrated evidence from flotation,zooarchaeology,ZooMS analysis and lithic artifacts,the preliminary inference is that the population lived in a hunting-gathering economy.They used lithic tools represented by arrowheads to hunt mainly Antilopinae animals(e.g.,Procapra gutturosa).Pollen analysis suggests that the climate was relatively humid,providing advantageous living conditions for the population.The climate evidence is consistent with a warm event at approximately 4.7 kyr BP.A dry-cold event(4.5–4.0 kyr BP)and the gradual expansion of agriculture and breeding might have resulted in the final decline of the population.This article provides new materials for research on the“last”hunter-gatherers in the steppe area of northern China.展开更多
Climate fluctuations in the past and in the future are likely to result in population expansions,shifts,or the contraction of the ecological niche of many species,and potentially leading to the changes in their geogra...Climate fluctuations in the past and in the future are likely to result in population expansions,shifts,or the contraction of the ecological niche of many species,and potentially leading to the changes in their geographical distributions.Prediction of suitable habitats has been developed as a useful tool for the assessment of habitat suitability and resource conservation to protect wildlife.Here,we model the ancestral demographic history of the extant modern Chinese Muntjac Muntiacus reevesi populations using approximate Bayesian computation(ABC)and used the maximum entropy model to simulate the past and predict the future spatial dynamics of the species under climate oscillations.Our results indicated that the suitable habitats for the M.reevesi shifted to the Southeast and contracted during the Last Glacial Maximum,whereas they covered a broader more northern position in the Middle Holocene.The ABC analyses revealed that the modern M.reevesi populations diverged in the Middle Holocene coinciding with the significant contraction of the highly suitable habitat areas.Furthermore,our predictions suggest that the potentially suitable environment distribution for the species will expand under all future climate scenarios.These results indicated that the M.reevesi diverged in the recent time after the glacial period and simultaneously as its habitat's expanded in the Middle Holocene.Furthermore,the past and future climate fluctuation triggered the change of Chinese muntjac spatial distribution,which has great influence on the Chinese muntjac's population demographic history.展开更多
基金financially supported by National Natural Science Foundation of China (Nos.41525021 and U1606401)。
文摘Based on high-resolution analysis to a 280-cm long sediment core obtained from the muddy area in the central Yellow Sea, we examined the provenance of muddy sediments and discussed the changing marine sedimentary environment since the middle Holocene. The results indicated that fine-grained sediments in the muddy area were mainly derived from the Huanghe(Yellow River) and Changjiang(Yangtze River) with considerable stepwise variations during the past 6.6 kyr. The Yellow Sea Warm Current was initiated at 6 kyr when the sea level was high together with the enhanced East Asian Winter Monsoon. These in combination established the framework of shelf circulation in the Yellow Sea that began to trap the river-derived fine-grained sediments. From 4.9 kyr to 2.8 kyr, both the Kushiro Current and East Asian Monsoon were significantly weakened, reducing the delivery of Changjiang sediments to the muddy area. As a result, the sediments were mainly originated from the Huanghe. From 2.8 kyr to 1.5 kyr the continuously weakened East Asian Winter Monsoon and enhanced Yellow Sea Warm Current entrapped more fine-grain sediments. Whereas the enhanced East Asian Winter Monsoon and the human caused increase in sediment load of the Huanghe since 1.5 kyr, and direct delivery of Huanghe sediments to the Yellow Sea during 1128–1855 AD might dominated the sedimentation in the study area. The stepwise variations of the sediment provenance and composition of the Central Yellow Sea muddy sediments are of importance to understanding the formation of muddy deposit in the central Yellow Sea and the associated variations of marine environment since the middle Holocene.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFC0500407)the National Natural Science Foundation of China(Grant Nos.41771217 and 32071599)。
文摘Peatlands are some of the largest carbon reservoirs in terrestrial ecosystems and play a key role in the global carbon cycle.Understanding peatland development,carbon accumulation processes,and the peatland response to varying forcing factors over different temporal and spatial scales helps reveal the underlying processes and general patterns of these ecosystems.To assess the role of climate and local conditions in peatland development,the basal samples from 23 peat cores and three well dated long peat cores were used to explore peatland initiation,lateral expansion,and carbon accumulation rate in the Baijianghe peatland located in the Changbai Mountains,Northeast China.Our results reveal that the Baijianghe peatland was initiated from forest conditions at 7.9 cal.kyr BP and then expanded laterally by paludification.The rapid expansion between 5 and4 cal.kyr BP likely resulted from high precipitation and gentle topography.The mean carbon accumulation rates of the three long peat cores were 36.3,39.1 and 48.4 g C m^(-2)yr^(-1),respectively,which are higher than rates from the northern peatlands.Both climate and local conditions have exerted an important influence on carbon accumulation rates in the Baijianghe peatland since the middle Holocene.The carbon accumulation patterns between 5 and 1.5 cal.kyr BP were probably linked to local conditions rather than climatic settings,including topography,hydrological conditions,and plant composition.The consistently decreasing carbon accumulation rate values at all locations within the BJH peatland over the last 1.5 cal.kyr BP suggests that climate is the primary control.This study highlights the varying primary controls on the process of peatland development and reveals the important role of local conditions in carbon accumulation.
基金The National Natural Science Foundation of China under contract Nos 42366002 and 41702182the National Key R&D Program of China under contract No.2017YFA0603300the Guangxi Scientific Projects under contract No.2018GXNSFAA281293。
文摘High-resolution sea-level data and high-precision dating of corals in the northern South China Sea(SCS)during the Holocene provide a reference and historical background for current and future sea-level changes and a basis for scientific assessment of the evolutionary trend of coral reefs in the SCS.Although sporadic studies have been performed around Hainan Island in the northern SCS,the reconstructed sea level presents different values or is controversial because the indicative meaning of the sea-level indicators were neither quantified nor uniform criteria.Here,we determined the quantitative relationship between modern living coral and sea level by measuring the top surfaces of 27 live Porites corals from the inner reef flat along the east coast of Hainan Island and assessed the accuracy of results obtained using coral as sea-level indicators.Additionally,three in situ fossil Porites corals were analyzed based on elevation measurements,digital X-ray radiography,and U-Th dating.The survey results showed that the indicative meanings for the modern live Porites corals is(146.09±8.35)cm below the mean tide level(MTL).It suggested that their upward growth limit is constrained by the sea level,and the lowest low water is the highest level of survival for the modern live Porites corals.Based on the newly defined indicative meanings,6 new sea-level index points(SLIPs)were obtained and 19 published SLIPs were recalculated.Those SLIPs indicated a relative sea level fluctuation between(227.7±9.8)cm to(154.88±9.8)cm MTL between(5393±25)cal a BP and(3390±12)cal a BP,providing evidences of the Mid-Holocene sea-level highstand in the northern SCS.Besides that,our analysis demonstrated that different sea-level histories may be produced based on different indicative meanings or criteria.The dataset of 276 coral U-Th ages indicates that coral reef development in the northern SCS comprised the initial development,boom growth,decline,and flourishing development again.A comparison with regional records indicated that synergistic effects of climatic and environmental factors were involved in the development of coral reefs in the northern SCS.Thus,the cessation of coral reef development during the Holocene in the northern SCS was probably associated with the dry and cold climate in South China,as reflected in the synchronous weakening of the ENSO and East Asian summer monsoon induced by the reduction of the 65°N summer insolation,which forced the migration of the Intertropical Convergence Zone.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB26000000)the National Basic Research Program of China(Grant No.2015CB953800)+1 种基金the National Social Science Fund of China(Grant No.18ZDA218)the Youth Innovation Promotion Association CAS(Grant No.2018099)。
文摘For a long time,the academic community has known very little about hunter-gatherers in the steppe area of northern China in the mid-Holocene.This article reports on the Ula Usu West site in Siziwangqi Banner,Inner Mongolia,including basic information about the site,animal bones,lithic artifacts and the environmental background.The age of the site is 4.8–4.4 cal.kyr BP,placing it in the Late Neolithic period.Considering integrated evidence from flotation,zooarchaeology,ZooMS analysis and lithic artifacts,the preliminary inference is that the population lived in a hunting-gathering economy.They used lithic tools represented by arrowheads to hunt mainly Antilopinae animals(e.g.,Procapra gutturosa).Pollen analysis suggests that the climate was relatively humid,providing advantageous living conditions for the population.The climate evidence is consistent with a warm event at approximately 4.7 kyr BP.A dry-cold event(4.5–4.0 kyr BP)and the gradual expansion of agriculture and breeding might have resulted in the final decline of the population.This article provides new materials for research on the“last”hunter-gatherers in the steppe area of northern China.
基金funded by the Key Science and Technology Financing Projects of the Ministry of Education(2012)the Scientific Research and Protection Project of Black Muntjac in Qianjiangyuan National Park,Zhejiang,China(2019-2021)+1 种基金the Biodiversity Survey,Monitoring and Assessment Project of Ministry of Ecology and Environment,China(Grant No.2019HB2096001006)the National Science&Technology Fundamental Resources Investigation Program of China(Grant No.2019FY101803).
文摘Climate fluctuations in the past and in the future are likely to result in population expansions,shifts,or the contraction of the ecological niche of many species,and potentially leading to the changes in their geographical distributions.Prediction of suitable habitats has been developed as a useful tool for the assessment of habitat suitability and resource conservation to protect wildlife.Here,we model the ancestral demographic history of the extant modern Chinese Muntjac Muntiacus reevesi populations using approximate Bayesian computation(ABC)and used the maximum entropy model to simulate the past and predict the future spatial dynamics of the species under climate oscillations.Our results indicated that the suitable habitats for the M.reevesi shifted to the Southeast and contracted during the Last Glacial Maximum,whereas they covered a broader more northern position in the Middle Holocene.The ABC analyses revealed that the modern M.reevesi populations diverged in the Middle Holocene coinciding with the significant contraction of the highly suitable habitat areas.Furthermore,our predictions suggest that the potentially suitable environment distribution for the species will expand under all future climate scenarios.These results indicated that the M.reevesi diverged in the recent time after the glacial period and simultaneously as its habitat's expanded in the Middle Holocene.Furthermore,the past and future climate fluctuation triggered the change of Chinese muntjac spatial distribution,which has great influence on the Chinese muntjac's population demographic history.