Pub Date : 2024-03-16DOI: 10.1177/09596836241236348
Letian He, Guoke Chen, Yishi Yang, Jianing He, Elizabeth Berger
The natural environment of the Gansu-Qinghai region in northwest China exhibits spatial variation, resulting in distinct adaptive strategies among populations in different geographical areas. In this study, we analyzed the diachronic trend and regional variations in caries prevalence among 10 different middle and late-Holocene groups by examining dental caries data to explore the correlation between different adaptation strategies and caries frequency. Frequency data was used to compare dental caries between populations, and the Chi-square test was employed to detect statistical differences. A multidisciplinary approach was employed to investigate the relationship between these changes and the adaptive strategies adopted by the populations in this region. The result shows that there was a gradual increase in caries prevalence over time in eastern Gansu, which corresponded with development of millet farming and social hierarchy. In the Hexi Corridor, caries prevalence exhibited fluctuations attributable to climate variability, human migration, and regime change. The research proposes that changes in adaptive strategies due to various social and environmental factors are reflected in human teeth, while also presenting a novel endeavor of aggregating a large, multisite bioarchaeological dataset in order to investigate the interactions between Holocene populations and palaeoenvironments in northwest China.
{"title":"Carious lesions as evidence for different adaptation strategies during the middle-late Holocene in the Gansu region, northwest China","authors":"Letian He, Guoke Chen, Yishi Yang, Jianing He, Elizabeth Berger","doi":"10.1177/09596836241236348","DOIUrl":"https://doi.org/10.1177/09596836241236348","url":null,"abstract":"The natural environment of the Gansu-Qinghai region in northwest China exhibits spatial variation, resulting in distinct adaptive strategies among populations in different geographical areas. In this study, we analyzed the diachronic trend and regional variations in caries prevalence among 10 different middle and late-Holocene groups by examining dental caries data to explore the correlation between different adaptation strategies and caries frequency. Frequency data was used to compare dental caries between populations, and the Chi-square test was employed to detect statistical differences. A multidisciplinary approach was employed to investigate the relationship between these changes and the adaptive strategies adopted by the populations in this region. The result shows that there was a gradual increase in caries prevalence over time in eastern Gansu, which corresponded with development of millet farming and social hierarchy. In the Hexi Corridor, caries prevalence exhibited fluctuations attributable to climate variability, human migration, and regime change. The research proposes that changes in adaptive strategies due to various social and environmental factors are reflected in human teeth, while also presenting a novel endeavor of aggregating a large, multisite bioarchaeological dataset in order to investigate the interactions between Holocene populations and palaeoenvironments in northwest China.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"69 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140151776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-16DOI: 10.1177/09596836241236320
Kai Nils Nitzsche, Naoto F Ishikawa, Toshihiro Yoshimura, Hiroto Kajita, Hodaka Kawahata, Nanako O Ogawa, Hisami Suga, Naohiko Ohkouchi
Polycyclic aromatic hydrocarbons (PAHs) are produced by incomplete combustion of biomass and fossil fuel, yet PAHs have been rarely analyzed in coastal sediment cores as a tracer for human activities before industrialization. The aim of this study was to assess if the historical trend of PAHs can be related to past human activities. To this end, we have determined the concentrations of PAHs in a 9 m-long sediment core from Osaka Bay, which records history of the last 2400 years. The concentration of PAHs before the beginning of the 17th century CE, the beginning of the peaceful Edo period, was consistently low (<100 ng g−1) and mainly comprised of smoke-derived PAHs reflecting the natural background. A relative higher abundance of 4−6 ring PAHs from the early 17th century CE and a higher PAH concentration from the early 18th century CE until approximately 1800 CE agreed with a population increase, Cu smelting activities and increasing combustion of charcoal. The constant PAH concentration until the late 19th century CE overlapped with a decline in the population in the Osaka area. An increasing PAH concentration from the late 19th century CE marked the beginning of industrialization in the Modern age. The peak in PAH concentration in 1945 CE was likely caused by burning of wooden structures due to air raids on Osaka City. A second peak around 1980 CE indicated the introduction of cleaner energies. We conclude that PAHs in coastal sediment cores can be used to reconstruct past human activities.
{"title":"Historical trend of polycyclic aromatic hydrocarbons in a sediment core from Osaka Bay during the Meghalayan","authors":"Kai Nils Nitzsche, Naoto F Ishikawa, Toshihiro Yoshimura, Hiroto Kajita, Hodaka Kawahata, Nanako O Ogawa, Hisami Suga, Naohiko Ohkouchi","doi":"10.1177/09596836241236320","DOIUrl":"https://doi.org/10.1177/09596836241236320","url":null,"abstract":"Polycyclic aromatic hydrocarbons (PAHs) are produced by incomplete combustion of biomass and fossil fuel, yet PAHs have been rarely analyzed in coastal sediment cores as a tracer for human activities before industrialization. The aim of this study was to assess if the historical trend of PAHs can be related to past human activities. To this end, we have determined the concentrations of PAHs in a 9 m-long sediment core from Osaka Bay, which records history of the last 2400 years. The concentration of PAHs before the beginning of the 17th century CE, the beginning of the peaceful Edo period, was consistently low (<100 ng g<jats:sup>−1</jats:sup>) and mainly comprised of smoke-derived PAHs reflecting the natural background. A relative higher abundance of 4−6 ring PAHs from the early 17th century CE and a higher PAH concentration from the early 18th century CE until approximately 1800 CE agreed with a population increase, Cu smelting activities and increasing combustion of charcoal. The constant PAH concentration until the late 19th century CE overlapped with a decline in the population in the Osaka area. An increasing PAH concentration from the late 19th century CE marked the beginning of industrialization in the Modern age. The peak in PAH concentration in 1945 CE was likely caused by burning of wooden structures due to air raids on Osaka City. A second peak around 1980 CE indicated the introduction of cleaner energies. We conclude that PAHs in coastal sediment cores can be used to reconstruct past human activities.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140151599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-16DOI: 10.1177/09596836241236324
Laura Lopera-Congote, Michael M. McGlue, Karlyn S Westover, Kevin Yeager, Laura Streib, Jeffery R Stone
Over the past several decades, increasing climate instability in the Sierra Nevada, California, expressed primarily as reduced winter precipitation and higher temperatures, has led to more frequent drought. High-altitude lakes in this region have been characterized as pristine ecosystems, but growing evidence suggests that they are responding acutely to climate change. To address this, we analyzed the diatom assemblages of two 210Pb dated sediment cores (Gull and June Lakes) from the eastern Sierra Nevada with the aim of assessing their sensitivity to and timing of responses to climate change at the end of the neoglacial (~1450 CE to ~1850 CE) and identifying how climate drivers can impact diatom communities. The nutrient cycles of both lakes have been disrupted by changes in thermal stratification, driven by increasing temperatures, as interpreted from the shift from a Stephanodiscus corruscus dominated ecosystem to a Stephanodiscus minutulus dominance. In this case, the June Lake (the deeper lake) diatom assemblage shifted from an assemblage representative of well mixed conditions to one representative of a stratified system before Gull Lake as a response to increasing temperatures and a strengthened thermocline. We relate the asynchronous change in the thermocline stability to basin morphology, where the deeper lake with a deeper thermocline is more sensitive to increasing temperatures. Further, generalized additive models (GAMs) allowed us to identify the onset of ecological change in both lakes, pointing to the termination of the Little Ice Age (LIA; ~1850 CE), revealing an acute response to changing climate.
{"title":"Detecting climate-driven ecological changes in high-altitude lakes in the Sierra Nevada, California","authors":"Laura Lopera-Congote, Michael M. McGlue, Karlyn S Westover, Kevin Yeager, Laura Streib, Jeffery R Stone","doi":"10.1177/09596836241236324","DOIUrl":"https://doi.org/10.1177/09596836241236324","url":null,"abstract":"Over the past several decades, increasing climate instability in the Sierra Nevada, California, expressed primarily as reduced winter precipitation and higher temperatures, has led to more frequent drought. High-altitude lakes in this region have been characterized as pristine ecosystems, but growing evidence suggests that they are responding acutely to climate change. To address this, we analyzed the diatom assemblages of two <jats:sup>210</jats:sup>Pb dated sediment cores (Gull and June Lakes) from the eastern Sierra Nevada with the aim of assessing their sensitivity to and timing of responses to climate change at the end of the neoglacial (~1450 CE to ~1850 CE) and identifying how climate drivers can impact diatom communities. The nutrient cycles of both lakes have been disrupted by changes in thermal stratification, driven by increasing temperatures, as interpreted from the shift from a Stephanodiscus corruscus dominated ecosystem to a Stephanodiscus minutulus dominance. In this case, the June Lake (the deeper lake) diatom assemblage shifted from an assemblage representative of well mixed conditions to one representative of a stratified system before Gull Lake as a response to increasing temperatures and a strengthened thermocline. We relate the asynchronous change in the thermocline stability to basin morphology, where the deeper lake with a deeper thermocline is more sensitive to increasing temperatures. Further, generalized additive models (GAMs) allowed us to identify the onset of ecological change in both lakes, pointing to the termination of the Little Ice Age (LIA; ~1850 CE), revealing an acute response to changing climate.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140156255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-15DOI: 10.1177/09596836241236349
Pablo E Ortiz, J Pablo Jayat, Agustina Novillo, Vanessa Torres-Carro, Franck Barbière
Based on a diverse Late-Holocene (1889–1743 cal yrs BP) small mammal assemblage (14 species, 204 individuals) resulting from the trophic activity of owls, we reconstruct the paleoenvironmental conditions of Las Chacritas area, Catamarca Province, northwestern Argentina. Twenty modern and one additional Late-Holocene samples from the region were used as comparative parameters in the paleoenvironmental reconstruction. Through direct comparison with a present-day assemblage from Las Chacritas, and using Nonmetric Multidimensional Scaling, spatial and temporal beta diversity (employing the Sorensen dissimilarity index), and the temporal beta diversity index (TBI) including all the small mammal samples, we quantitatively reconstruct the relationships among modern and Late-Holocene assemblages. Direct comparison showed significant differences, with relative abundances changing markedly over time, with several species of the Late-Holocene assemblage absent in the modern sample whereas many species frequent in the modern community absent in the Late-Holocene. NMDS analysis associated the Late-Holocene assemblage with modern samples of western drier environments. Beta diversity was low for presence-absence and moderate for abundance data, with higher contribution of turnover than nestedness, although for abundance data the proportion of nestedness was higher. TBI showed high variation among both Holocene sites and their present-day counterparts, whereas species gains dominated in modern samples. Our results suggest that the habitats surrounding Las Chacritas have modified markedly since the Late-Holocene. Presence of species today frequent in arid environments and absence of forest-dwelling species suggest that open, dry and relatively rocky habitats characterized this area in that interval.
{"title":"Late-Holocene environmental conditions revealed by a small mammal assemblage in mountain areas of Northwestern Argentina","authors":"Pablo E Ortiz, J Pablo Jayat, Agustina Novillo, Vanessa Torres-Carro, Franck Barbière","doi":"10.1177/09596836241236349","DOIUrl":"https://doi.org/10.1177/09596836241236349","url":null,"abstract":"Based on a diverse Late-Holocene (1889–1743 cal yrs BP) small mammal assemblage (14 species, 204 individuals) resulting from the trophic activity of owls, we reconstruct the paleoenvironmental conditions of Las Chacritas area, Catamarca Province, northwestern Argentina. Twenty modern and one additional Late-Holocene samples from the region were used as comparative parameters in the paleoenvironmental reconstruction. Through direct comparison with a present-day assemblage from Las Chacritas, and using Nonmetric Multidimensional Scaling, spatial and temporal beta diversity (employing the Sorensen dissimilarity index), and the temporal beta diversity index (TBI) including all the small mammal samples, we quantitatively reconstruct the relationships among modern and Late-Holocene assemblages. Direct comparison showed significant differences, with relative abundances changing markedly over time, with several species of the Late-Holocene assemblage absent in the modern sample whereas many species frequent in the modern community absent in the Late-Holocene. NMDS analysis associated the Late-Holocene assemblage with modern samples of western drier environments. Beta diversity was low for presence-absence and moderate for abundance data, with higher contribution of turnover than nestedness, although for abundance data the proportion of nestedness was higher. TBI showed high variation among both Holocene sites and their present-day counterparts, whereas species gains dominated in modern samples. Our results suggest that the habitats surrounding Las Chacritas have modified markedly since the Late-Holocene. Presence of species today frequent in arid environments and absence of forest-dwelling species suggest that open, dry and relatively rocky habitats characterized this area in that interval.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"133 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140151597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-15DOI: 10.1177/09596836241236347
GS Joju, Anish Kumar Warrier, BS Mahesh, AS Yamuna Sali, Cheryl A Noronha-D’Mello, K Balakrishna, Rahul Mohan
We present a high-resolution record of environmental changes during the Mid-Late Holocene obtained from a lake sediment core covering the past 4.87 cal kyr BP in the Schirmacher Oasis, East Antarctica. The magnetic signal of Lake L6 was found to be primarily controlled by catchment-derived ferrimagnetic minerals. The period between 4.87 and 3.35 cal kyr BP is marked by several episodes of cold and warm conditions. Warm and wet conditions prevailed in the region from 3.35 to 2.43 cal kyr BP. Magnetic susceptibility values remained generally low indicating the pedogenic formation of fine magnetic grains. The high values of the chemical weathering indices reflected the warm and wet conditions conducive to chemical weathering. A transition to cold and dry conditions was observed at around 2.43 cal kyr BP, representing the Neoglacial cooling, with high values of magnetic concentration-dependent parameters. Following the Neoglacial period, a return to warm and wet conditions was observed at 1.63 cal kyr BP, coeval with the Medieval Climate Anomaly. Our record shows a Late-Holocene cooling marked by a sudden increase in magnetic susceptibility values, which could represent the Little Ice Age, followed by a shift to warmer conditions near the core top.
我们从南极洲东部施尔马赫绿洲（Schirmacher Oasis）的一个湖泊沉积物岩芯中获得了全新世中晚期环境变化的高分辨率记录，该记录涵盖了公元前 4.87 千年的时间。研究发现，L6 湖的磁信号主要受集水区铁磁矿物的控制。公元前 4.87 至公元前 3.35 千年期间出现了几次冷暖交替的情况。公元前 3.35 至公元前 2.43 年期间，该地区普遍温暖潮湿。磁感应强度值总体保持在较低水平，这表明细小磁性颗粒是由泥土形成的。化学风化指数值较高，反映了温暖潮湿的条件有利于化学风化。在大约 2.43 cal kyr BP 时，观察到向寒冷干燥条件的过渡，这代表了新冰期的冷却，磁浓度相关参数值较高。在新冰期之后，于公元前 1.63 千年恢复到温暖湿润的条件，与中世纪气候异常同时出现。我们的记录显示，晚全新世的降温以磁感应强度值的突然增加为标志，这可能代表了小冰河时期，随后在岩心顶部附近的条件转为温暖。
{"title":"A high-resolution record of Mid- to Late-Holocene environmental changes from a land-locked lake in Schirmacher Oasis, East Antarctica","authors":"GS Joju, Anish Kumar Warrier, BS Mahesh, AS Yamuna Sali, Cheryl A Noronha-D’Mello, K Balakrishna, Rahul Mohan","doi":"10.1177/09596836241236347","DOIUrl":"https://doi.org/10.1177/09596836241236347","url":null,"abstract":"We present a high-resolution record of environmental changes during the Mid-Late Holocene obtained from a lake sediment core covering the past 4.87 cal kyr BP in the Schirmacher Oasis, East Antarctica. The magnetic signal of Lake L6 was found to be primarily controlled by catchment-derived ferrimagnetic minerals. The period between 4.87 and 3.35 cal kyr BP is marked by several episodes of cold and warm conditions. Warm and wet conditions prevailed in the region from 3.35 to 2.43 cal kyr BP. Magnetic susceptibility values remained generally low indicating the pedogenic formation of fine magnetic grains. The high values of the chemical weathering indices reflected the warm and wet conditions conducive to chemical weathering. A transition to cold and dry conditions was observed at around 2.43 cal kyr BP, representing the Neoglacial cooling, with high values of magnetic concentration-dependent parameters. Following the Neoglacial period, a return to warm and wet conditions was observed at 1.63 cal kyr BP, coeval with the Medieval Climate Anomaly. Our record shows a Late-Holocene cooling marked by a sudden increase in magnetic susceptibility values, which could represent the Little Ice Age, followed by a shift to warmer conditions near the core top.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140151605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-15DOI: 10.1177/09596836241236340
Gina E Hannon, Richard HW Bradshaw, Richard C Chiverrell, Jens Peter Skovsgaard
Pollen, plant macrofossils and charcoal analyses were used to study tree diversity, fire history and forest disturbance over the past c. 3500 years at three forest remnant sites in Vendsyssel, northern Denmark. All locations had a more diverse tree composition in the past including abundant Alnus, Betula, Corylus, Pinus, Quercus, Salix, Tilia and Ulmus. The changes in tree diversity through time can be attributed to a combination of factors including climate change, burning linked to shifting cultivation, grazing and felling. The balance between arboreal and non-arboreal pollen was already being influenced by human activities in the late Bronze Age c. 3000 years ago. The high pollen abundance values recorded for Tilia pre-2000 years ago are exceptional as compared to later periods at these sites. At one location, the transition from Tilia to Fagus indicated that Tilia prevailed until c. 1300 years ago. Subsequent periods of forest clearance, with charcoal and cereal cultivation, initially including Hordeum and subsequently also Secale, were recorded. There was pollen evidence for grazing followed by shrub regeneration including Calluna, Erica, Juniperus and herbaceous taxa, and following that, a forest recovery of mainly Fagus, Picea and Pinus. This recovery is also recorded in historical forest records from 1880 CE onwards, emphasising the dominant role of plantation schemes. Results are placed in a wider framework of other sites in Denmark and southern Scandinavia, which have also documented a reduction of tree diversity and forest cover over the same period. The evidence from the long-term record is used to draw conclusions to assist forest restoration programmes.
{"title":"The history of Fagus sylvatica at its northern limit in Vendsyssel, Denmark","authors":"Gina E Hannon, Richard HW Bradshaw, Richard C Chiverrell, Jens Peter Skovsgaard","doi":"10.1177/09596836241236340","DOIUrl":"https://doi.org/10.1177/09596836241236340","url":null,"abstract":"Pollen, plant macrofossils and charcoal analyses were used to study tree diversity, fire history and forest disturbance over the past c. 3500 years at three forest remnant sites in Vendsyssel, northern Denmark. All locations had a more diverse tree composition in the past including abundant Alnus, Betula, Corylus, Pinus, Quercus, Salix, Tilia and Ulmus. The changes in tree diversity through time can be attributed to a combination of factors including climate change, burning linked to shifting cultivation, grazing and felling. The balance between arboreal and non-arboreal pollen was already being influenced by human activities in the late Bronze Age c. 3000 years ago. The high pollen abundance values recorded for Tilia pre-2000 years ago are exceptional as compared to later periods at these sites. At one location, the transition from Tilia to Fagus indicated that Tilia prevailed until c. 1300 years ago. Subsequent periods of forest clearance, with charcoal and cereal cultivation, initially including Hordeum and subsequently also Secale, were recorded. There was pollen evidence for grazing followed by shrub regeneration including Calluna, Erica, Juniperus and herbaceous taxa, and following that, a forest recovery of mainly Fagus, Picea and Pinus. This recovery is also recorded in historical forest records from 1880 CE onwards, emphasising the dominant role of plantation schemes. Results are placed in a wider framework of other sites in Denmark and southern Scandinavia, which have also documented a reduction of tree diversity and forest cover over the same period. The evidence from the long-term record is used to draw conclusions to assist forest restoration programmes.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"134 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140151774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The interactions of the different monsoon systems across Southeast Asia create extreme climate phenomena. Central Vietnam, located near the centre of this transitional region, has encountered numerous effects. As a result, its sediments from lakes or speleothems are valuable archives for interpreting past climate variability. However, there is still a lack of high-resolution paleoenvironmental and palaeoclimatic reconstructions during the Holocene in Vietnam. Our study presents a paleoenvironmental diatom-based record of sediment cores collected from Biển Hồ maar lake (14°03′N, 108°00′E) in the Central Highlands of Vietnam covering nearly the entire Holocene. Based on changes in diatom assemblages in the sediment sequence, we identified two periods of the Early Holocene (~11,700–7800 cal BP) and the Mid- to Late-Holocene (~7800–360 cal BP), which mark a remarkable shift in the environment around Biển Hồ. Alternations of key diatom species during the Early Holocene indicate intensity variations between water-mixing and thermal stratification mechanisms in meso-eutrophic conditions. During the Mid- to Late-Holocene, the complete dominance of Aulacoseira granulata var. granulata implies year-round destratification and intense mixing of the lake water column in a permanently eutrophic environment. Its morphological variability reveals intervals of dry environmental conditions driven by pronounced droughts across the Asian continent.
东南亚不同季风系统的相互作用造成了极端气候现象。越南中部位于这一过渡区域的中心附近，受到了许多影响。因此，其湖泊或岩浆沉积物是解读过去气候变异性的宝贵档案。然而，越南全新世期间仍然缺乏高分辨率的古环境和古气候重建。我们的研究展示了从越南中部高原碧沦湖（北纬 14°03′，东经 108°00′）采集的沉积岩芯中获得的基于硅藻的古环境记录，几乎涵盖了整个全新世。根据沉积序列中硅藻群的变化，我们确定了全新世早期（约公元前11700-7800年）和全新世中晚期（约公元前7800-360年）两个时期，这两个时期标志着碧洱海周围环境的显著变化。全新世早期主要硅藻物种的变化表明，在中富营养化条件下，混水机制和热分层机制之间的强度变化。在全新世中期至晚期，颗粒硅藻（Aulacoseira granulata var. granulata）完全占据主导地位，这意味着在长期富营养化的环境中，湖泊水体全年都在去分层和剧烈混合。它的形态变化揭示了整个亚洲大陆明显干旱所导致的干旱环境条件的间歇期。
{"title":"Diatom-based indications of an environmental regime shift and droughts associated with seasonal monsoons during the Holocene in Biển Hồ maar lake, the Central Highlands, Vietnam","authors":"Hoàn Đào-Trung, Yu Fukumoto, Dương Nguyễn-Thùy, Thành Đinh-Xuân, Thái Nguyễn-Đình, Ingmar Unkel, Hướng Nguyễn-Văn","doi":"10.1177/09596836241236342","DOIUrl":"https://doi.org/10.1177/09596836241236342","url":null,"abstract":"The interactions of the different monsoon systems across Southeast Asia create extreme climate phenomena. Central Vietnam, located near the centre of this transitional region, has encountered numerous effects. As a result, its sediments from lakes or speleothems are valuable archives for interpreting past climate variability. However, there is still a lack of high-resolution paleoenvironmental and palaeoclimatic reconstructions during the Holocene in Vietnam. Our study presents a paleoenvironmental diatom-based record of sediment cores collected from Biển Hồ maar lake (14°03′N, 108°00′E) in the Central Highlands of Vietnam covering nearly the entire Holocene. Based on changes in diatom assemblages in the sediment sequence, we identified two periods of the Early Holocene (~11,700–7800 cal BP) and the Mid- to Late-Holocene (~7800–360 cal BP), which mark a remarkable shift in the environment around Biển Hồ. Alternations of key diatom species during the Early Holocene indicate intensity variations between water-mixing and thermal stratification mechanisms in meso-eutrophic conditions. During the Mid- to Late-Holocene, the complete dominance of Aulacoseira granulata var. granulata implies year-round destratification and intense mixing of the lake water column in a permanently eutrophic environment. Its morphological variability reveals intervals of dry environmental conditions driven by pronounced droughts across the Asian continent.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"133 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140151603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-12DOI: 10.1177/09596836241236326
Marc-Antoine Leclerc, Martin Simard, Olivier Blarquez, Hubert Morin
Characterizing disturbance regimes over long time scales is paramount for describing and identifying their variability. The most important biotic disturbance in the eastern Canadian boreal forest is the defoliation caused by the eastern spruce budworm, a moth of the insect order Lepidoptera. Lepidopteran scales have recently been used to reconstruct spruce budworm population fluctuations throughout the Holocene. However, this novel proxy has yet to be compared to an independent proxy. This study aimed to determine whether lepidopteran scales found in the surface sediments of boreal lakes tracked large spruce budworm populations, that is, outbreaks, using yearly aerial surveys (1967–present) of spruce budworm defoliation as an independent proxy. Scales were extracted (1 cm resolution) from the top 20 cm of 210Pb-dated sediment cores recovered from nine lakes. To identify significant abundance peaks of scales in the time series, we removed background noise using a modified version of CharAnalysis. A 100-year smoothing window width combined with a 60th percentile threshold yielded the highest true positive and true negative occurrences, and the lowest false positive and false negative occurrences, with values of 0.69 and 0.70 for Cohen’s Kappa and Matthews correlation coefficient, respectively. Our findings demonstrate that lepidopteran scales are a suitable proxy for identifying spruce budworm outbreaks in the sediment record enabling the reconstruction of budworm and other lepidopteran species outbreak dynamics at millennial timescales.
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Endorheic river basins and their terminal lakes are highly sensitive to climate change and human activities. Based on chemical and pollen indicators, lake level, and erosion/accumulation rates of rivers, we explore the phasing of the evolution of the river system in the Hexi Corridor during the Holocene. The results suggest that climate change dominated the evolution of the river system during the early-Mid-Holocene. Entering the historical period, humans began to have an impact on runoff, water resources, and lake evolution, and since 1000 BP, anthropogenic perturbations recorded by regional proxies increased and humans dominated the migrations of river . In addition, we discuss the widespread erosion of rivers in the global endorheic zone and the impact of human activities in this context and found the timing of human influence on river evolution is not the same in different regions.
{"title":"The evolution of river systems under the influence of climate change and human activities in the endorheic zones during the Holocene","authors":"Mingjun Gao, Yu Li, Zhansen Zhang, Junjie Duan, Yaxin Xue, Simin Peng, Hao Shang, Shiyu Liu","doi":"10.1177/09596836241236344","DOIUrl":"https://doi.org/10.1177/09596836241236344","url":null,"abstract":"Endorheic river basins and their terminal lakes are highly sensitive to climate change and human activities. Based on chemical and pollen indicators, lake level, and erosion/accumulation rates of rivers, we explore the phasing of the evolution of the river system in the Hexi Corridor during the Holocene. The results suggest that climate change dominated the evolution of the river system during the early-Mid-Holocene. Entering the historical period, humans began to have an impact on runoff, water resources, and lake evolution, and since 1000 BP, anthropogenic perturbations recorded by regional proxies increased and humans dominated the migrations of river . In addition, we discuss the widespread erosion of rivers in the global endorheic zone and the impact of human activities in this context and found the timing of human influence on river evolution is not the same in different regions.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140126986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-29DOI: 10.1177/09596836241231446
Carlos R Belotti López de Medina
This paper presents an exploratory study on the taxonomic diversity of pre-Hispanic archaeofaunas in the South-Central Andes (SCA; western South America) from the Pleistocene-Holocene boundary to the Late-Holocene. The SCA is a complex of diverse environments and has undergone distinct climate events for the last 13,000 years, such as the occurrence of warmer and drier conditions in the Middle-Holocene. The South-Central Andean area was part of the larger Andes interaction area, which was a primary center for animal and plant domestication and the emergence of agro-pastoralist economies. Since subsistence was key to these processes, the SCA provides a relevant case study on the interactions among environment, foodways and sociocultural evolution. Taxonomic diversity was used here as a proxy for diet breadth. A total of 268 archaeofaunal assemblages were sampled from the zooarchaeological literature. Reviewed variables included the cultural chronology and spatial coordinates of the assemblages, as well as the presence and abundance of taxa at the family rank. Taxonomic diversity covered two dimensions: composition (families present in each assemblage) and structure (quantitative relationships among taxa), which was measured through richness (NTAXA), ubiquity and relative abundance (NISP based rank-order). Despite the uneven distribution of samples, the analyses revealed the following trends: (1) a moderate relationship between NTAXA and distance from coastline for most of the Holocene; (2) a potential decrease in assemblage richness for coastal ecoregions during the Late-Holocene; and (3) a generalized increase in the relative abundance of Camelidae.
{"title":"Diet breadth and biodiversity in the pre-hispanic South-Central Andes (Western South America) during the Holocene: An exploratory analysis and review","authors":"Carlos R Belotti López de Medina","doi":"10.1177/09596836241231446","DOIUrl":"https://doi.org/10.1177/09596836241231446","url":null,"abstract":"This paper presents an exploratory study on the taxonomic diversity of pre-Hispanic archaeofaunas in the South-Central Andes (SCA; western South America) from the Pleistocene-Holocene boundary to the Late-Holocene. The SCA is a complex of diverse environments and has undergone distinct climate events for the last 13,000 years, such as the occurrence of warmer and drier conditions in the Middle-Holocene. The South-Central Andean area was part of the larger Andes interaction area, which was a primary center for animal and plant domestication and the emergence of agro-pastoralist economies. Since subsistence was key to these processes, the SCA provides a relevant case study on the interactions among environment, foodways and sociocultural evolution. Taxonomic diversity was used here as a proxy for diet breadth. A total of 268 archaeofaunal assemblages were sampled from the zooarchaeological literature. Reviewed variables included the cultural chronology and spatial coordinates of the assemblages, as well as the presence and abundance of taxa at the family rank. Taxonomic diversity covered two dimensions: composition (families present in each assemblage) and structure (quantitative relationships among taxa), which was measured through richness (NTAXA), ubiquity and relative abundance (NISP based rank-order). Despite the uneven distribution of samples, the analyses revealed the following trends: (1) a moderate relationship between NTAXA and distance from coastline for most of the Holocene; (2) a potential decrease in assemblage richness for coastal ecoregions during the Late-Holocene; and (3) a generalized increase in the relative abundance of Camelidae.","PeriodicalId":517388,"journal":{"name":"The Holocene","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140007705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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