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Biome reconstruction on the Tibetan Plateau since the last glacial maximum using a machine learning method

Science China Earth Sciences 2022年第3期65卷 518-535页

作者： Feng QIN Yan ZHAO Xianyong CAO Key Laboratory ofLand Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Alpine Paleoecology and Human Adaptation(ALPHA)Group State Key Laboratory of Tibetan Plateau Earth System Science(LATPES)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Historical biome changes on the Tibetan Plateau provide important information that improves our understanding of the alpine vegetation responses to climate ***,a comprehensively quantitative reconstruction of the historical Tibetan Plateau biomes is not possible due to the lack of quantitative methods that enable appropriate classification of alpine biomes based on proxy data such as fossil pollen *** this study,a pollen-based biome classification model was developed by applying a random forest algorithm(a supervised machine learning method)based on modern pollen assemblages on and around the Tibetan Plateau,and its robustness was assessed by comparing its results with the predictions of the biomisation *** results indicated that modern biome distributions reconstructed using the random forest model based on modern pollen data generally concurred with the observed zonal *** random forest model had a significantly higher accuracy than the biomisation method,indicating the former is a more suitable tool for reconstructing alpine biome changes on the Tibetan *** random forest model was then applied to reconstruct the Tibetan Plateau biome changes from 22 ka BP to the present based on 51 fossil pollen *** reconstructed biome distribution changes on the Tibetan Plateau generally corresponded to global climate changes and Asian monsoon *** the last glacial maximum,the Tibetan Plateau was mainly desert with subtropical forests distributed in the *** the last deglaciation,the alpine steppe began expanding and gradually became zonal vegetation in the central and eastern *** meadow occupied the eastern and southeastern areas of the Tibetan Plateau since the early Holocene,and the forest-meadow-steppe-desert pattern running southeast to northwest on the Tibetan Plateau was established *** the mid-Holocene,subtropical forests extended north,which reflected the“optimum”***

关键词： Biome reconstruction Random forest algorithm Biomisation method Pollen data last glacial maximum Tibetan Plateau

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Ecological and hydrologic evolution history in the sensitive zone of both East Asian summer monsoon and Westerly since the last glacial maximum

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Journal of Mountain Science 2023年第5期20卷 1266-1281页

作者： LI Yu PENG Si-min Key Laboratory of Western China’s Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesCenter for Hydrologic Cycle and Water Resources in Arid RegionLanzhou UniversityLanzhou 730000China

The Qilian Mountains,located in the northeastern Qinghai-Tibet Plateau,is a sensitive zone of both East Asian summer monsoon(EASM)and westerly winds(WW).The evolution history and driving mechanism of the ecosystem and hydrologic cycle in this region on long-term timescales have not yet been *** this study,we comprehensively study the hydrologic and ecological evolution history in the sensitive zone since the last glacial maximum(LGM)by integrating surface sediments,paleoclimate records,TraCE-21ka transient simulations,and PMIP3-CMIP5 multi-model *** show that hydrologic and ecological proxies from surface sediments are significantly different from west to east and mainly divided into three sections:the monsoonaffected region in the eastern Qilian Mountains,the intersection region in the central Qilian Mountains,and the westerly-affected region in the western Qilian ***,paleo-ecological and paleohydrologic reconstructions from the surroundings uncover a synchronous climate evolution that the EASM mainly controls the eastern Qilian Mountains and penetrates the central Qilian Mountains in monsoon intensity maximum,while the WW dominates the central and western Qilian Mountains on both glacial-interglacial and millennial *** simulation results further bear out the glacial humid climate in the central and western Qilian Mountains caused by the enhanced WW,and the humidity maximum in the eastern Qilian Mountains controlled by the strong mid-Holocene *** general,east-west differences in climate pattern and response for the EASM and the WW are integrally stable on both short-term and long-term timescales.

关键词： EastAsian summer monsoon Westerly winds last glacial maximum Ecological and hydrologic evolution history Qilian Mountains

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The Southern Annular Mode(SAM) in PMIP2 Simulations of the last glacial maximum

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Advances in Atmospheric Sciences 2014年第4期31卷 863-878页

作者： Seong-Joong KIM L Junmei Baek-Min KIM Korea Polar Research Institute KORDI Chinese Academy of Meteorological Sciences

The increasing trend of the Southern Annular Mode （SAM） in recent decades has influenced climate change in the Southem Hemisphere （SH）.How the SAM will respond increased greenhouse gas concentrations in the future remains *** the variability of the SAM in the past under a colder climate such as during the last glacial maximum （LGM） might provide some understanding of the response of the SAM under a future warmer *** analyzed the changes in the SAM during the LGM in comparison to pre-industrial （PI） simulations using five coupled ocean-atmosphere models （CCSM,FGOALS,IPSL,MIROC,HadCM） from the second phase of the Paleoclimate Modelling Intercomparison Project （PMIP2）.In CCSM,MIROC,IPSL,and FGOALS,the variability of the simulated SAM appears to be reduced in the LGM compared to the PI simulations,with a decrease in the standard deviation of the SAM ***,four out of the five models suggest a weaker SAM amplitude in the LGM consistent with a weaker SH polar vortex and westerly winds found in some proxy records and model *** weakening of the SAM in the LGM was associated with an increase in the vertical propagation of Rossby waves in southern high latitudes.

关键词： Southern Annular Mode last glacial maximum PMIP2 Southern Hemisphere westerly winds

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The PMIP3 Simulated Climate Changes over Arid Central Asia during the Mid-Holocene and last glacial maximum

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Acta Geologica Sinica(English Edition) 2020年第3期94卷 725-742页

作者： XU Hongna WANG Tao WANG Huijun MIAO Jiapeng CHEN Jianhui CHEN Shengqian Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China Climate Change Research Center Chinese Academy of SciencesBeijing 100029China Nansen-Zhu International Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Key Laboratory of Meteorological Disaster Nanjing University of Information Science and TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100029China Key Laboratory of Western China's Environmental Systems College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China

In this study, the climate changes over Arid Central Asia(ACA) during the mid-Holocene(approximately 6,000 calendar years ago, MH) and the last glacial maximum(approximately 21,000 calendar years ago, LGM) were investigated using multimodel simulations derived from the Paleoclimate Modelling Intercomparison Project Phase 3(PMIP3). During the MH, the multimodel median(MMM) shows that in the core region of ACA, the regionally averaged annual surface air temperature(SAT) decreases by 0.13°C and annual precipitation decreases by 3.45%, compared with the preindustrial(PI) climate. The MMM of the SAT increases by 1.67/0.13°C in summer/autumn, whereas it decreases by 1.23/1.11°C in spring/winter. The amplitude of the seasonal cycles of the SAT increases over ACA due to different MH orbital parameters. For precipitation, the regionally averaged MMM decreases by 5.77%/5.69%/0.39%/5.24% in spring/summer/autumn/winter, respectively. Based on the analysis of the aridity index(AI), compared with the PI, a drier climate appears in southern Central Asia and western Xinjiang due to decreasing precipitation. During the LGM, the MMM shows that the regionally averaged SAT decreases by 5.04/4.36/4.70/5.12/5.88°C and precipitation decreases by 27.78%/28.16%/31.56%/27.74%/23.29% annually and in the spring, summer, autumn, and winter, respectively. Robust drying occurs throughout almost the whole core area. Decreasing precipitation plays a dominant role in shaping the drier conditions, whereas strong cooling plays a secondary but opposite role. In response to the LGM external forcings, over Central Asia and Xinjiang, the seasonal cycle of precipitation has a smaller amplitude compared with that under the PI climate. In the model-data comparison, the simulated MH moisture changes over ACA are to some extent consistent with the reconstructions, further confirming that drier conditions occurred during that period than during the PI.

关键词： PMIP3 climate changes Arid Central Asia mid-Holocene last glacial maximum

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A Matrilineal Genetic Legacy from the last glacial maximum Confers Susceptibility to Schizophrenia in Han Chinese

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Journal of Genetics and Genomics 2014年第7期41卷 397-407页

作者： Wen Zhang Jinsong Tang A-Mei Zhang Min-Sheng Peng Hai-Bing Xie Liwen Tan Lin Xu Ya-Ping Zhang Xiaogang Chen Yong-Gang Yao Key Laboratory of Animal Models and Human Disease Mechanisms Kunming Institute of ZoologyChinese Academy of Sciences The Institute of Mental Health the Second Xiangya HospitalCentral South University State Key Laboratory of Genetic Resources and Evolution Kunming Institute of ZoologyChinese Academy of Sciences National Technology Institute of Psychiatry Key Laboratory of Psychiatry and Mental Health of Hunan ProvinceCentral South University

Mitochondrial dysfunction has been widely reported in schizophrenia patients. To dissect the matrilineal structure of Han Chinese with or without schizophrenia and to decipher the maternal influence and evolutionary history of schizophrenia, a total of 1212 schizophrenia patients and 1005 matched healthy controls, all of Han Chinese origin, were recruited in Hunan Province, China. We classified haplogroup for each individual based on mitochondrial DNA （mtDNA） sequence variations and compared the haplogroup distribution pattern between cases and controls. Haplogroup B5a presented a higher frequency in cases than in controls （P = 0.02, OR = 1.67, 95% CI = [1.09, 2.56]）, and this result could be confirmed by permutation analysis. Age estimation of haplogroup B5a in cases revealed a much younger age than that of controls, which was coincident with the Northern Hemisphere deglaciation at the end of the last glacial maximum. Analysis of complete mtDNA in five patients belonging to haplogroup B5a showed that this background effect might be caused by haplogroup- defining variants m.8584G〉A and m.10398A〉G. Our results showed that matrilineal risk factor for schizophrenia had an ancient origin and might acquire a predisposing effect on schizophrenia due to the environment change and/or orchestration with other nuclear genetic factors appeared recently in human evolutionary history.

关键词： mtDNA haplogroup Schizophrenia Association last glacial maximum Evolutionary medicine

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Artemisia pollen-indicated steppe distribution in southern China during the last glacial maximum

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Journal of Palaeogeography 2013年第3期2卷 297-305页

作者： Liu Hongyan Liu Kan Wei Fangling Department of Ecology and Ministry of Education Key Laboratory of Earth Surface Processes College of Urban and Environmental SciencesPeking University

The last glacial maximum (LGM) was the coldest period during the previous 20,000 *** have been different points of views on steppe distribution during the LGM period in southern China,partly due to the different interpretations of Artemisia *** make a reliable interpretation of the pollen fossil Artemisia,the modern distribution of Artemisia species and the relationship of pollen with climate and vegetation over a large spatial scale in China was thoroughly *** about Artemisia species and pollen distributions used in this paper were collected from published works completed by other researchers as well as *** southern limit of steppe vegetation during the LGM period was interpreted from the published contour map of Artemisia pollen percentages during the *** species in China are mostly distributed either in the horizontally distributed steppe regions or in the vertically distributed desert-steppe in the desert region,which indicates a cold and dry *** steppe is a distribution center of Artemisia *** of Artemisia in surface pollen assemblages are lower in both the desert and the temperate *** high Artemisia species cover nor high percentages of Artemisia pollen were found in the coast areas of ***-five percent of Artemisia pollen in sediments might indicate a local occurrence of steppe *** of Artemisia pollen in the subtropical and tropical forest are less than 10%.A close relationship between Artemisia pollen and temperate steppe in China is *** southern edge of the steppe vegetation during the LGM might be along the middle reach of the Yangtze *** results support the hypothesis that the isolated high fraction of Artemisia pollen along the northern edge of the South China Sea was transported from a large source area.

关键词： pollen steppe Artemisia last glacial maximum LGM South China Sea

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The terrestrial NPP simulations in China since last glacial maximum

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Science Bulletin 2005年第18期 108-113页

作者： HE Yong1, DAN Li2, DONG Wenjie1,2, JI Jinjun3,2 & QIN Dahe1 1. National Climate Center, China Meteorological Administration, Bei-jing 100081, China 2. Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 3. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

Based on Atmosphere-Vegetation Interaction Model (AVIM), the magnitude and spatial distribution of terrestrial net primary productivity (NPP) in China is simu-lated during three different geological eras, last glacial maximum (LGM), Mid-Holocene (MH) and the present. The simulation shows that the glacial-interglacial variation of East Asian summer monsoon in China is the key factor af-fecting the NPP change. During the three eras, mean NPPs are 208 g/m2·a, 409 g/m2·a, and 355 g/m2·a. The total NPPs are 2.05 Pg/a, 3.89 Pg/a and 3.33 Pg/a, respectively. The ter-restrial NPP in China during warm-humid climate is larger than that during cold-arid eras, and the correlation analysis between NPP and climate factors suggests that temperature is the primary factor affecting the terrestrial NPP during 21 kaBP (LGM), and for 6 kaBP (MH) and the present the pri-mary factor is precipitation.

关键词： last glacial maximum Mid-Holocene NPP East-Asian monsoon climate change.

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Chinese Loess Plateau vegetation since the last glacial maximum and its implications for vegetation restoration

Chinese Loess Plateau vegetation since the Last Glacial Maxi...

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中国科学院地质与地球物理研究所2013年度（第13届）...

作者： Wenying Jiang Yufen Cheng Xiaoxiao Yang Shiling Yang Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of Sciences School of Earth Sciences and Resources China University of Geosciences

*** has been investing heavily in afforestation programmes to control soil erosion on the vast Chinese Loess Plateau(CLP).This massive afforestation has led to a considerable increase in forest and a decrease in dust-storm activity in some ***,there have also been some negative outcomes,including low tree survival rate,increased soil erosion, exacerbated water shortages and deep soil *** important explanation for these is the use of inappropriate species because of a lack of knowledge of the natural vegetation in the area,which has been largely destroyed by human activities. *** vegetation in the most recent warm period(the early-mid-Holocene) can serve as an analogue for the ongoing greening programme,particularly under the global warming scenario. In this study,the natural vegetation of the CLP since the last glacial maximum (LGM) was reconstructed from pollen analyses of six loess sections. *** results show that herbs were dominant both in the cold-dry LGM and the warmhumid *** the LGM,vegetation in the north-western CLP mainly consisted of Artemisia,Echinops-type,Taraxacum-type and Chenopodiaceae,and vegetation in the south-eastern CLP was characterized by the same types but with a slightly higher incidence of *** the early-mid-Holocene,vegetation was more diverse, with Poaceae,Artemisia,Echinops-type and Chenopodiaceae dominant in the north-west,and Pinus,Corylus,Poaceae,Artemisia and Selaginella sinensis dominant in the south-east. *** and *** ecological restoration of herbs should be considered a priority, although trees and shrubs have been prioritized *** balance environmental conservation and farm-income support objectives,we suggest planting Corylus,Juglans and *** in the south-eastern Chinese Loess Plateau(CLP) because of their edible value or medicinal *** the considerable prevalence of Selaginella sinensis and the Asteraceae f

关键词： arid and semi-arid climate herb Holocene last glacial maximum loess natural vegetation pollen records

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Warming-induced northwestward migration of the East Asian monsoon rain belt from the last glacial maximum to the mid-Holocene

Warming-induced northwestward migration of the East Asian mo...

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中国科学院地质与地球物理研究所2015年度（第15届）...

作者： Shiling Yang Zhongli Ding Yangyang Li Xu Wang Wenying Jiang Xiaofang Huang Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences

glacial–interglacial changes in the distribution of C/C vegetation on the Chinese Loess Plateau have been related to East Asian summer monsoon intensity and position, and could provide insights into future changes caused by global warming. Here, we present δC records of bulk organic matter since the last glacial maximum(LGM) from 21 loess sections across the Loess Plateau. The δC values(range: –25‰ to –16‰) increased gradually both from the LGM to the mid-Holocene in each section and from northwest to southeast in each time interval. During the LGM, C biomass increased from40% in the southeast. The spatial pattern of C biomass in both the LGM and the mid-Holocene closely resembles that of modern warm-season precipitation, and thus can serve as a robust analog for the contemporary East Asian summer monsoon rain belt. Using the 10–20% isolines for C biomass in the cold LGM as a reference, we derived a minimum 300-km northwestward migration of the monsoon rain belt for the warm Holocene. Our results strongly support the prediction that Earth’s thermal equator will move northward in a warmer world. The southward displacement of the monsoon rain belt and the drying trend observed during the last few decades in northern China will soon reverse as global warming continues.

关键词： C4 plants loess East Asian summer monsoon last glacial maximum Holocene

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Southern Annular Mode（SAM）for the last glacial maximum Derived from PMIP2 Coupled Model Simulations

Southern Annular Mode（SAM）for the Last Glacial Maximum Der...

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第八次全国动力气象学术会议

作者： Seong-Joong Kim Junmei Lü Baek-Min Kim Korea Polar Research Institute KORDI Chinese Academy of Meteorological Sciences

＜正＞The increasing trend of the Southern Annular Mode（SAM） in recent decades has influenced the climate change in the southern *** will the SAM respond to the increase of greenhouse gases in the future still remains *** the variability of the SAM in the past under colder climate such as the last glacial maximum （LGM） helps understand the response of the SAM for the future warm *** analyzed

关键词： Southern Annular Mode last glacial maximum PMIP2 SH westerly winds

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