Peat sediments and peatland evolution process offer abundant clues into the history of vegetation and climate changes.In order to reconstruct Holocene peatland, vegetation and climate changes on eastern Tibetan Platea...Peat sediments and peatland evolution process offer abundant clues into the history of vegetation and climate changes.In order to reconstruct Holocene peatland, vegetation and climate changes on eastern Tibetan Plateau, we conducted analyses of fossil pollen, loss-on-ignition, and carbon accumulation rate on one peat core from Zoige Basin. Our results show local peatland initiated at 10.3 ka, thrived in the early-mid Holocene, and then began to degrade. Throughout the Holocene, Zoige Basin was dominated by alpine meadow. Coniferous forest on montane regions expanded for several times during 10.5–4.6ka, and then dramatically retreated. Results of peatland property, principal component analysis on fossil pollen suggested the climate maintained warm/wet during 10–5.5 ka, and became relatively cold/dry in the late Holocene. Rapid degradation of peatland, retreat of coniferous forest and climatic drought/cooling occurred at 10.2–10, 9.7–9.5, 8.7–8.5, 7.7–7.4, 6.4–6, 5.5–5.2,4.8–4.5, 4–3.6, 3.1–2.7, 1.4–1.2 and 0.8–0.6 ka. The long-term variations of Holocene climate and vegetation on eastern Tibetan Plateau could be attributed to changes in insolation-driven temperature and Asian Summer Monsoon intensity, while those rapid centennial changes were probably triggered by abrupt monsoon failures and temperature anomalies in the high northern latitudes.展开更多
In China, study on fossil Zygnemataceae has newly attracted the attention of palynologists. In our study of the bottom sediments in the East China Sea and Yellow Sea, Zygnemataeeae have for tthe first time been found ...In China, study on fossil Zygnemataceae has newly attracted the attention of palynologists. In our study of the bottom sediments in the East China Sea and Yellow Sea, Zygnemataeeae have for tthe first time been found abundant in many column sections of Late Pleistocene peat bed, often in company with fresh water algae and pollen of hydrophyte, providing a useful evidence for the paleoenvironmental research of the East China Sea and Yellow Sea of that time.展开更多
Understanding the response of ecosystems to past climate is critical for evaluating the impacts of future climate changes.A large-scale abrupt shift of vegetation in response to the Holocene gradual climate changes ha...Understanding the response of ecosystems to past climate is critical for evaluating the impacts of future climate changes.A large-scale abrupt shift of vegetation in response to the Holocene gradual climate changes has been well documented for the Sahara-Sahel ecosystem. Whether such a non-linear response is of universal significance remains to be further addressed. Here,we examine the vegetation-climate relationships in central Asia based on a compilation of 38 high-quality pollen records. The results show that the Holocene vegetation experienced two major abrupt shifts, one in the early Holocene(Shift I, establishing shift) and another in the late Holocene(Shift II, collapsing shift), while the mid-Holocene vegetation remained rather stable. The timings of these shifts in different regions are asynchronous, which are not readily linkable with any known abrupt climate shifts,but are highly correlated with the local rainfalls. These new findings suggest that the observed vegetation shifts are attributable to the threshold effects of the orbital-induced gradual climate changes. During the early Holocene, the orbital-induced precipitation increase would have first reached the threshold for vegetation "establishment" for moister areas, but significantly later for drier areas. In contrast, the orbital-induced precipitation decrease during the late Holocene would have first reached the threshold, and led to the vegetation "collapse" for drier areas, but delayed for moister areas. The well-known 4.2 kyr BP drought event and human intervention would have also helped the vegetation collapses at some sites. These interpretations are strongly supported by our surface pollen-climate analyses and ecosystem simulations. These results also imply that future climate changes may cause abrupt changes in the dry ecosystem once the threshold is reached.展开更多
A universal method of molecular dating that can be applied to all families and genera regardless of their fossil records, or lack thereof, is highly desirable. A possible method for eudicots is to use a large phylogen...A universal method of molecular dating that can be applied to all families and genera regardless of their fossil records, or lack thereof, is highly desirable. A possible method for eudicots is to use a large phylogeny calibrated using deep fossils including tricolpate pollen as a fixed （124 mya） calibration point. This method was used to calculate node ages within three species-poor disjunct basal eudicot genera, Caulophyllum, Podophyllum and Pachysandra, and sensitivity of these ages to effects such as taxon sampling were then quantified. By deleting from one to three accessions related to each genus in 112 different combinations, a confidence range describing variation due only to taxon sampling was generated. Ranges for Caulophyllum, Podophyllum and Pachysandra were 8.4-10.6, 7.6-20.0, and 17.6-25.0 mya, respectively. However, the confidence ranges calculated using bootstrapping were much wider, at 3-19, 0-32 and 11-32 mya, respectively. Furthermore, deleting 10 adjacent taxa had a large effect in Pachysandra only, indicating that undersampling effects are significant among Buxales. Changes to sampling density in neighboring clades, or to the position of the fixed fossil calibration point had small to negligible effects. Non-parametric rate smoothing was more sensitive to taxon sampling effects than was penalized likelihood. The wide range for Podophyllum, compared to the other two genera, was probably due to a high degree of rate heterogeneity within this genus. Confidence ranges calculated by this method could be narrowed by sampling more individuals within the genus of interest, and by sequencing multiple DNA regions from all species in the phylogeny.展开更多
Fossil pollen records from 45 sites across China were evaluated and synthesized to document vegetation and climate change during Marine Isotope Stage 3(MIS 3)at 60–27 ka and to understand the large-scale controls.Dur...Fossil pollen records from 45 sites across China were evaluated and synthesized to document vegetation and climate change during Marine Isotope Stage 3(MIS 3)at 60–27 ka and to understand the large-scale controls.During MIS3, vegetation type was dominantly forest in eastern China, forest steppe/meadow in the north and Tibetan Plateau, and steppe desert in northwestern arid China. We developed a semi-quantitative vegetation index to reflect change in plant abundance(by inferring the general climate conditions), with a vegetation score from 1to 3 based on the different vegetation types inferred from pollen data at individual sites at intervals of 2,000 years.The reconstructed vegetation index shows higher values during MIS 3, especially during the period 53–40 ka, than at the Last Glacial Maximum. Our results also suggest that climate on the basis of vegetation change was cooler and drier during MIS 3 than during the Holocene optimum;however, MIS 3 vegetation was probably similar to modern vegetation. The close relationship between vegetation change, insolation and Asian summer monsoon strength suggests that climate variations, probably in both temperature and precipitation, are the primary drivers of regional vegetation change. Additional well-dated, high-resolution palaeoclimate records from many locations across China will be needed to understand the vegetation change and climate forcings on millennial and centennial scales within MIS 3.展开更多
This paper deals with a new integrated method of reconstruction and forecasting of climatic changes in future. The method is based on proxy data pollen-spore analysis method, 14C analysis method, nowadays meteorologic...This paper deals with a new integrated method of reconstruction and forecasting of climatic changes in future. The method is based on proxy data pollen-spore analysis method, 14C analysis method, nowadays meteorological data, and data about of solar activity expressed in numbers of W （Wolf）. Here we present the results of investigation of sediments of the 2nd Fomich River terrace, Taymyr Peninsula, Russia. The formation of the peat bog started 10500 ± 140 years BP and continued during the entire Holocene. The pollen analysis of the sediment samples of the 2nd Fomich River terrace and the analysis of surface samples from a larch forest, typical of this region, reveals two phytochrones： both climatically preconditioned--tundra phytochrone （I1-4） and forest phytochrone （Ⅱ1-4）. The techniques of reconstruction and forecasting of basic elements of climate are presented and discussed in details.展开更多
The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia. The high species diversity of...The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia. The high species diversity of Dipterocarpaceae in SE Asian rain forests suggests its origin from SE Asia. However, its fossil history is much younger, from Oligocene, from the region. Based on the pollen fossil records from the late Cretaceous-early Paleogene sedimentary sequences of Indian subcontinent and the contemporaneous distribution of its extant taxa, evolutionary history of Dipterocarpaceae has been traced. The study suggests a West Gondwanan origin for this family. Present study also provides first evidence of Dipterocarpaceae genus Vateriopsis (endemic in Seychelles) type fossil pollen record from the late Cretaceous and early Palaeogene sedimentary sequences of western Indian margin.展开更多
The Lipovtsy flora originates mostly from the synonymous Formation exposed at the coal quarries in the Razdolnaya( Suifun) River Basin in Heilongjiang Province( China) and Primorye Region( Russia). The thorough study ...The Lipovtsy flora originates mostly from the synonymous Formation exposed at the coal quarries in the Razdolnaya( Suifun) River Basin in Heilongjiang Province( China) and Primorye Region( Russia). The thorough study of this flora has revealed its high diversity and abundance. One of the most prominent groups in the Lipovtsy flora is the ferns. Next in diversity are conifers( Miroviaceae,Taxodiaceae,Podozamitaceae,Taxaceae,Cephalotaxaceae). It was revealed the remarkable quantity of bennettitalean remains( 24 taxa). The main peculiarity of this flora is the appearance of first angiosperms( pollen,dispersed cuticle,leaves). The fine preservation of the cuticles from the coals allows us to research the taxonomical composition of peat-forming plants and clear main components of the swamp plant communities. These plants supplied the material for the accumulation of resinite coals on the territory of Razdolnaya River Basin were conifers Miroviaceae,taxodialeans,bennettites,as well as gleicheniaceous and cyatheaceous ferns.展开更多
Abstract： The present study is an attempt to apply the concept of plant and pollen indicators to habitat conditions in different soil strata at archaeological site （Lake Qarun）. It revealed a great palaeoenvironmen...Abstract： The present study is an attempt to apply the concept of plant and pollen indicators to habitat conditions in different soil strata at archaeological site （Lake Qarun）. It revealed a great palaeoenvironmental information＇s about habitat changing of Lake Qarun from a humid and wet conditions during the Hellenic Period to reed swampy early Roman, to Nile Flooding middle Roman, to mesophytic habitats Late Roman, also changing to halophytic and salt marshes with presence of Chenopodiaceae at recent time. Using indicator plants and their remains i.e. pollen grains and spores, palynological studies of different soil strata revealed that, presence of 13 pollen and spore types e.g. Lycopodium, Typhaceae type, Juncaceae, Poaceae, Cyperaceae, Caryophyllaceae, Chenopodiaceae, Nymphaeaceae, Fabaceae, Asteraceae, Tamaricaceae, Onagraceae and Lamiaceae. The data obtained were valuable in reconstruct past vegetation and habitats conditions of Lake Qarun during Helleno Roman period.展开更多
青藏高原自然环境受人类干扰相对较小,为利用古孢粉记录重建气候因子提供了可能,高原过去气候因子的重建对于预测未来气候变化趋势有重要意义.通过选取的29条高原化石孢粉记录,利用现代类比法和化石孢粉点与高原气温的函数关系,把化石...青藏高原自然环境受人类干扰相对较小,为利用古孢粉记录重建气候因子提供了可能,高原过去气候因子的重建对于预测未来气候变化趋势有重要意义.通过选取的29条高原化石孢粉记录,利用现代类比法和化石孢粉点与高原气温的函数关系,把化石孢粉点古气温转化为青藏高原古气温,重建了高原全新世1月和7月古气温序列.结果表明：对于1月和7月气温而言,全新世早期（11.5~8.5ka BP）为气温波动上升期;全新世中期（8.5~4.6 ka BP）为全新世大暖期,气温整体高于现代;全新世晚期（4.6 ka BP~至今）又可分为两个阶段,一个是4.6~2.4 ka BP,在此阶段1月和7月气温都有减小的趋势,另一个阶段则是2.4 ka BP至今,气温出现反常的趋势.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0600501)the National Natural Science Foundation of China(Grant Nos.41471169,41330105,41102221,41690113&41401228)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB03030103)
文摘Peat sediments and peatland evolution process offer abundant clues into the history of vegetation and climate changes.In order to reconstruct Holocene peatland, vegetation and climate changes on eastern Tibetan Plateau, we conducted analyses of fossil pollen, loss-on-ignition, and carbon accumulation rate on one peat core from Zoige Basin. Our results show local peatland initiated at 10.3 ka, thrived in the early-mid Holocene, and then began to degrade. Throughout the Holocene, Zoige Basin was dominated by alpine meadow. Coniferous forest on montane regions expanded for several times during 10.5–4.6ka, and then dramatically retreated. Results of peatland property, principal component analysis on fossil pollen suggested the climate maintained warm/wet during 10–5.5 ka, and became relatively cold/dry in the late Holocene. Rapid degradation of peatland, retreat of coniferous forest and climatic drought/cooling occurred at 10.2–10, 9.7–9.5, 8.7–8.5, 7.7–7.4, 6.4–6, 5.5–5.2,4.8–4.5, 4–3.6, 3.1–2.7, 1.4–1.2 and 0.8–0.6 ka. The long-term variations of Holocene climate and vegetation on eastern Tibetan Plateau could be attributed to changes in insolation-driven temperature and Asian Summer Monsoon intensity, while those rapid centennial changes were probably triggered by abrupt monsoon failures and temperature anomalies in the high northern latitudes.
文摘In China, study on fossil Zygnemataceae has newly attracted the attention of palynologists. In our study of the bottom sediments in the East China Sea and Yellow Sea, Zygnemataeeae have for tthe first time been found abundant in many column sections of Late Pleistocene peat bed, often in company with fresh water algae and pollen of hydrophyte, providing a useful evidence for the paleoenvironmental research of the East China Sea and Yellow Sea of that time.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41330105, 41690113 and 41430531)the National Key Research and Development Program of China (Grant No. 2016YFA0600501)the Chinese Academy of Sciences Strategic Priority Research Program (Grant No. XDB03030000)
文摘Understanding the response of ecosystems to past climate is critical for evaluating the impacts of future climate changes.A large-scale abrupt shift of vegetation in response to the Holocene gradual climate changes has been well documented for the Sahara-Sahel ecosystem. Whether such a non-linear response is of universal significance remains to be further addressed. Here,we examine the vegetation-climate relationships in central Asia based on a compilation of 38 high-quality pollen records. The results show that the Holocene vegetation experienced two major abrupt shifts, one in the early Holocene(Shift I, establishing shift) and another in the late Holocene(Shift II, collapsing shift), while the mid-Holocene vegetation remained rather stable. The timings of these shifts in different regions are asynchronous, which are not readily linkable with any known abrupt climate shifts,but are highly correlated with the local rainfalls. These new findings suggest that the observed vegetation shifts are attributable to the threshold effects of the orbital-induced gradual climate changes. During the early Holocene, the orbital-induced precipitation increase would have first reached the threshold for vegetation "establishment" for moister areas, but significantly later for drier areas. In contrast, the orbital-induced precipitation decrease during the late Holocene would have first reached the threshold, and led to the vegetation "collapse" for drier areas, but delayed for moister areas. The well-known 4.2 kyr BP drought event and human intervention would have also helped the vegetation collapses at some sites. These interpretations are strongly supported by our surface pollen-climate analyses and ecosystem simulations. These results also imply that future climate changes may cause abrupt changes in the dry ecosystem once the threshold is reached.
基金NERC (fellowship NE/B500658/1) for the financial support that made this work possible
文摘A universal method of molecular dating that can be applied to all families and genera regardless of their fossil records, or lack thereof, is highly desirable. A possible method for eudicots is to use a large phylogeny calibrated using deep fossils including tricolpate pollen as a fixed （124 mya） calibration point. This method was used to calculate node ages within three species-poor disjunct basal eudicot genera, Caulophyllum, Podophyllum and Pachysandra, and sensitivity of these ages to effects such as taxon sampling were then quantified. By deleting from one to three accessions related to each genus in 112 different combinations, a confidence range describing variation due only to taxon sampling was generated. Ranges for Caulophyllum, Podophyllum and Pachysandra were 8.4-10.6, 7.6-20.0, and 17.6-25.0 mya, respectively. However, the confidence ranges calculated using bootstrapping were much wider, at 3-19, 0-32 and 11-32 mya, respectively. Furthermore, deleting 10 adjacent taxa had a large effect in Pachysandra only, indicating that undersampling effects are significant among Buxales. Changes to sampling density in neighboring clades, or to the position of the fixed fossil calibration point had small to negligible effects. Non-parametric rate smoothing was more sensitive to taxon sampling effects than was penalized likelihood. The wide range for Podophyllum, compared to the other two genera, was probably due to a high degree of rate heterogeneity within this genus. Confidence ranges calculated by this method could be narrowed by sampling more individuals within the genus of interest, and by sequencing multiple DNA regions from all species in the phylogeny.
基金supported by the Hundred Talents Programme of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(41125006,41330105)Humboldt Research Fellowship for Experienced Researchers
文摘Fossil pollen records from 45 sites across China were evaluated and synthesized to document vegetation and climate change during Marine Isotope Stage 3(MIS 3)at 60–27 ka and to understand the large-scale controls.During MIS3, vegetation type was dominantly forest in eastern China, forest steppe/meadow in the north and Tibetan Plateau, and steppe desert in northwestern arid China. We developed a semi-quantitative vegetation index to reflect change in plant abundance(by inferring the general climate conditions), with a vegetation score from 1to 3 based on the different vegetation types inferred from pollen data at individual sites at intervals of 2,000 years.The reconstructed vegetation index shows higher values during MIS 3, especially during the period 53–40 ka, than at the Last Glacial Maximum. Our results also suggest that climate on the basis of vegetation change was cooler and drier during MIS 3 than during the Holocene optimum;however, MIS 3 vegetation was probably similar to modern vegetation. The close relationship between vegetation change, insolation and Asian summer monsoon strength suggests that climate variations, probably in both temperature and precipitation, are the primary drivers of regional vegetation change. Additional well-dated, high-resolution palaeoclimate records from many locations across China will be needed to understand the vegetation change and climate forcings on millennial and centennial scales within MIS 3.
文摘This paper deals with a new integrated method of reconstruction and forecasting of climatic changes in future. The method is based on proxy data pollen-spore analysis method, 14C analysis method, nowadays meteorological data, and data about of solar activity expressed in numbers of W （Wolf）. Here we present the results of investigation of sediments of the 2nd Fomich River terrace, Taymyr Peninsula, Russia. The formation of the peat bog started 10500 ± 140 years BP and continued during the entire Holocene. The pollen analysis of the sediment samples of the 2nd Fomich River terrace and the analysis of surface samples from a larch forest, typical of this region, reveals two phytochrones： both climatically preconditioned--tundra phytochrone （I1-4） and forest phytochrone （Ⅱ1-4）. The techniques of reconstruction and forecasting of basic elements of climate are presented and discussed in details.
文摘The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia. The high species diversity of Dipterocarpaceae in SE Asian rain forests suggests its origin from SE Asia. However, its fossil history is much younger, from Oligocene, from the region. Based on the pollen fossil records from the late Cretaceous-early Paleogene sedimentary sequences of Indian subcontinent and the contemporaneous distribution of its extant taxa, evolutionary history of Dipterocarpaceae has been traced. The study suggests a West Gondwanan origin for this family. Present study also provides first evidence of Dipterocarpaceae genus Vateriopsis (endemic in Seychelles) type fossil pollen record from the late Cretaceous and early Palaeogene sedimentary sequences of western Indian margin.
基金Supported by project of Russian Foundation for Basic Research(No.16-04-01411)
文摘The Lipovtsy flora originates mostly from the synonymous Formation exposed at the coal quarries in the Razdolnaya( Suifun) River Basin in Heilongjiang Province( China) and Primorye Region( Russia). The thorough study of this flora has revealed its high diversity and abundance. One of the most prominent groups in the Lipovtsy flora is the ferns. Next in diversity are conifers( Miroviaceae,Taxodiaceae,Podozamitaceae,Taxaceae,Cephalotaxaceae). It was revealed the remarkable quantity of bennettitalean remains( 24 taxa). The main peculiarity of this flora is the appearance of first angiosperms( pollen,dispersed cuticle,leaves). The fine preservation of the cuticles from the coals allows us to research the taxonomical composition of peat-forming plants and clear main components of the swamp plant communities. These plants supplied the material for the accumulation of resinite coals on the territory of Razdolnaya River Basin were conifers Miroviaceae,taxodialeans,bennettites,as well as gleicheniaceous and cyatheaceous ferns.
文摘Abstract： The present study is an attempt to apply the concept of plant and pollen indicators to habitat conditions in different soil strata at archaeological site （Lake Qarun）. It revealed a great palaeoenvironmental information＇s about habitat changing of Lake Qarun from a humid and wet conditions during the Hellenic Period to reed swampy early Roman, to Nile Flooding middle Roman, to mesophytic habitats Late Roman, also changing to halophytic and salt marshes with presence of Chenopodiaceae at recent time. Using indicator plants and their remains i.e. pollen grains and spores, palynological studies of different soil strata revealed that, presence of 13 pollen and spore types e.g. Lycopodium, Typhaceae type, Juncaceae, Poaceae, Cyperaceae, Caryophyllaceae, Chenopodiaceae, Nymphaeaceae, Fabaceae, Asteraceae, Tamaricaceae, Onagraceae and Lamiaceae. The data obtained were valuable in reconstruct past vegetation and habitats conditions of Lake Qarun during Helleno Roman period.
文摘青藏高原自然环境受人类干扰相对较小,为利用古孢粉记录重建气候因子提供了可能,高原过去气候因子的重建对于预测未来气候变化趋势有重要意义.通过选取的29条高原化石孢粉记录,利用现代类比法和化石孢粉点与高原气温的函数关系,把化石孢粉点古气温转化为青藏高原古气温,重建了高原全新世1月和7月古气温序列.结果表明：对于1月和7月气温而言,全新世早期（11.5~8.5ka BP）为气温波动上升期;全新世中期（8.5~4.6 ka BP）为全新世大暖期,气温整体高于现代;全新世晚期（4.6 ka BP~至今）又可分为两个阶段,一个是4.6~2.4 ka BP,在此阶段1月和7月气温都有减小的趋势,另一个阶段则是2.4 ka BP至今,气温出现反常的趋势.
