Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauracea...Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauraceae and to analyse their relationships to current climate and past climate change.Methods:We used ensembles of small models(ESMs)to map the current distributions of 353 Lauraceae species in China and calculatedβ_(sor)and itsβ_(sim)andβ_(sne)components.We tested the relationship betweenβ_(sor),β_(sne)andβ_(sim)with current climate and past climate change related predictors using a series of simultaneous autoregressive(SAR_(err))models.Results:Spatial distribution ofβ_(sor)of Lauraceae is positively correlated with latitude,showing an inverse rela-tionship to the latitudinalα-diversity(species richness)gradient.Highβ_(sor)occurs at the boundaries of the warm temperate and subtropical zones and at the Qinghai-Tibet Plateau due to highβ_(sne).The optimized SAR_(err)model explainsβ_(sor)andβ_(sne)well,but notβ_(sim).Current mean annual temperature determinesβ_(sor)andβ_(sne)of Lauraceae more than anomalies and velocities of temperature or precipitation since the Last Glacial Maximum.Conclusions:Current low temperatures and high climatic heterogeneity are the main factors explaining the high multi-siteβ-diversity of Lauraceae.In contrast to analyses of theβ-diversity of entire species assemblages,studies of single plant families can provide complementary insights into the drivers ofβ-diversity of evolutionarily more narrowly defined entities.展开更多
In dendroclimatology,tree ring chronology is ordinarily established to reveal the fluctuation law of climate change on the interannual,interdecadal,and centennial scales.However,since traditional dendrochronology can ...In dendroclimatology,tree ring chronology is ordinarily established to reveal the fluctuation law of climate change on the interannual,interdecadal,and centennial scales.However,since traditional dendrochronology can only use one variable(tree ring width)to reflect environmentally related information,this causes the richer information recorded in the tree rings to be discarded.In this study,we examined the potential of hyperspectral chronological indices(shortened as“hyperspectral index/indices”)with samples collected in Shennongjia woodland in central China.The correlation analysis of the tree ring series on different samples indicated that hyperspectral indices outperform the traditional width index in chronology statistics including Signal-to-noise Ratio(SNR)and Expressed Population Signal(EPS).The reliability test shows that hyperspectral chronologies have more periods reaching the threshold of EPS or Subsample Signal Strength(SSS)>0.85,which means that hyperspectral chronologies provide more reliable periods for accurate climate reconstruction.Based on this,chronologies built by the three dendroclimatic indices were used to reconstruct the average temperature changes in Shennongjia over the last 103 years.The reconstruction results indicate that in our study area,the traditional width index model failed the split-sample calibration test and exhibited a low reconstruction accuracy,while the hyperspectral index model has a higher explained variance of 46.4%(p<0.01),compared to the width index(21.4%)and the grayscale index(38.3%).Our research results show that hyperspectral indices have greater potential for climate reconstruction in regions with lower susceptibility to climate stress.This is attributed to their ability to effectively extract subtle climate signals from the spectral variations on the surface of tree rings.Such ring spectral changes may be caused by complex and currently unknown responses of the trees to the climate.展开更多
The Coupled Model Intercomparison Project （CMIP） is an international community-based infrastructure that supports climate model intercomparison, climate variability, climate prediction, and climate projection. Impro...The Coupled Model Intercomparison Project （CMIP） is an international community-based infrastructure that supports climate model intercomparison, climate variability, climate prediction, and climate projection. Improving the performance of climate models over East Asia and the western North Pacific has been a challenge for the climate-modeling community. In this paper, we provide a synthesis robustness analysis of the climate models participating in CMIP-Phase 5 （CMIP5）. The strengths and weaknesses of the CMIP5 models are assessed from the perspective of climate mean state, interannual variability, past climate change during the mid-Pliocene （MP） and the last millennium, and climate projection. The added values of regional climate models relative to the driving global climate models are also assessed. Although an encouraging increase in credibility and an improvement in the simulation of mean states, interannual variability, and past climate changes are visible in the progression from CMIP3 to CMIPS, some previously noticed biases such as the ridge position of the western North Pacific subtropical high and the associated rainfall bias are still evident in CMIP5 models. Weaknesses are also evident in simulations of the interannual amplitude, such as El Nino- Southern Oscillation （ENSO）-monsoon relationships. Coupled models generally show better results than standalone atmospheric models in simulating both mean states and interannual variability. Multi-model intercomparison indicates significant uncertainties in the future projection of climate change, although precipitation increases consistently across models constrained by the Clausius-Clapeyron relation. Regional ocean-atmosphere coupled models are recommended for the dynamical downscaling of climate change oroiections over the East Asia-western North Pacific domain.展开更多
The occurrence of bumper or poor grain harvests in ancient China plays an important role in explaining how past climate changes affected the economy.Because of the lack of long-term continuous and high-resolution quan...The occurrence of bumper or poor grain harvests in ancient China plays an important role in explaining how past climate changes affected the economy.Because of the lack of long-term continuous and high-resolution quantitative data for reconstructing the series of grain harvests in ancient China,understanding of the impacts and mechanisms involved in climate change is limited.This study presents a method designed for reconstructing grain harvest series by quantifying grain output levels based on the descriptions in historical documents.The method involves setting the grain output level for each year based on very specific meanings of different words,calculating a yield index based on the structure of each level and assessing grain yields(bumper or poor harvests)every 10 years.First,1636 records related to grain yields(including crop yields,food security,agricultural disasters,grain prices,grain storage and people's livelihoods)for each year were retrieved from history books called the Twenty-Four Histories.Second,using this method,a 10-year resolution graded grain harvest series from the Western Han Dynasty to the Five Dynasties(206 BC–960 AD)is reconstructed.Finally,the relationship between the variations in temperature and precipitation and the fluctuation of grain yields is examined.The results show that from the Western Han Dynasty to the Five Dynasties,bumper,average and poor harvest decades accounted for 33.3%,39.3%and 27.4%of the 1,166-year period,respectively.The grain yields during 206 BC–960 AD can be divided into three stages:a period of bumper harvests during 206–51 BC,poor harvests during 50 BC–590 AD and bumper harvests during 591–960 AD.Bumper harvest decades typically experienced a warm climate with normal or high levels of precipitation,while poor harvest decades had a cold and dry climate.A positive correlation was found between temperature and grain yield because a warm climate allows a full use of resources.The observed relationship between precipitation and grain yield indicated that both flooding and droughts cause poor harvests,which confirms that agricultural production in the monsoon climate of eastern China is greatly impacted by conditions of limited heat and extreme precipitation.展开更多
This paper gives a definition of earth system model and shows three development phases of it, including physical climate system model, earth climate system model, and earth system model, based on an inves- tigation of...This paper gives a definition of earth system model and shows three development phases of it, including physical climate system model, earth climate system model, and earth system model, based on an inves- tigation of climate system models in the world. It provides an expatiation on the strategic significance of future development of earth system model, an introduction of some representative scientific research plans on development of earth system model home and abroad, and a review of its status and trends based on the models of the fourth assessment report （AR4） ofthe Intergovernmental Panel on Climate Change （IPCC）. Some suggestions on future development of earth system model in China are given, which are expected to be helpful to advance the development.展开更多
基金This work was financially supported by the National Key Research and Development Program of China(Grant No.2016YFC0502101)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.SQ2019QZKK1603)a Visiting Scholarship funded by the China Scholarship Council(Grant No.202004910612).
文摘Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauraceae and to analyse their relationships to current climate and past climate change.Methods:We used ensembles of small models(ESMs)to map the current distributions of 353 Lauraceae species in China and calculatedβ_(sor)and itsβ_(sim)andβ_(sne)components.We tested the relationship betweenβ_(sor),β_(sne)andβ_(sim)with current climate and past climate change related predictors using a series of simultaneous autoregressive(SAR_(err))models.Results:Spatial distribution ofβ_(sor)of Lauraceae is positively correlated with latitude,showing an inverse rela-tionship to the latitudinalα-diversity(species richness)gradient.Highβ_(sor)occurs at the boundaries of the warm temperate and subtropical zones and at the Qinghai-Tibet Plateau due to highβ_(sne).The optimized SAR_(err)model explainsβ_(sor)andβ_(sne)well,but notβ_(sim).Current mean annual temperature determinesβ_(sor)andβ_(sne)of Lauraceae more than anomalies and velocities of temperature or precipitation since the Last Glacial Maximum.Conclusions:Current low temperatures and high climatic heterogeneity are the main factors explaining the high multi-siteβ-diversity of Lauraceae.In contrast to analyses of theβ-diversity of entire species assemblages,studies of single plant families can provide complementary insights into the drivers ofβ-diversity of evolutionarily more narrowly defined entities.
基金supported by the National Natural Science Foundation of China(NSFC)Projects[grant numbers 42271476 and 41771227]Key Technology Projects of the Hubei Provincial Company of the China National Tobacco Corporation(grant number 027Y2021-020 and 027Y2022-006)Young Scholar of Wuhan University 351 Talent Program[grant number 202017].
文摘In dendroclimatology,tree ring chronology is ordinarily established to reveal the fluctuation law of climate change on the interannual,interdecadal,and centennial scales.However,since traditional dendrochronology can only use one variable(tree ring width)to reflect environmentally related information,this causes the richer information recorded in the tree rings to be discarded.In this study,we examined the potential of hyperspectral chronological indices(shortened as“hyperspectral index/indices”)with samples collected in Shennongjia woodland in central China.The correlation analysis of the tree ring series on different samples indicated that hyperspectral indices outperform the traditional width index in chronology statistics including Signal-to-noise Ratio(SNR)and Expressed Population Signal(EPS).The reliability test shows that hyperspectral chronologies have more periods reaching the threshold of EPS or Subsample Signal Strength(SSS)>0.85,which means that hyperspectral chronologies provide more reliable periods for accurate climate reconstruction.Based on this,chronologies built by the three dendroclimatic indices were used to reconstruct the average temperature changes in Shennongjia over the last 103 years.The reconstruction results indicate that in our study area,the traditional width index model failed the split-sample calibration test and exhibited a low reconstruction accuracy,while the hyperspectral index model has a higher explained variance of 46.4%(p<0.01),compared to the width index(21.4%)and the grayscale index(38.3%).Our research results show that hyperspectral indices have greater potential for climate reconstruction in regions with lower susceptibility to climate stress.This is attributed to their ability to effectively extract subtle climate signals from the spectral variations on the surface of tree rings.Such ring spectral changes may be caused by complex and currently unknown responses of the trees to the climate.
基金This work is jointly supported by the National Natural Science Foundation of China （41420104006 and 41330423）, and by the R＆D Special Fund for Public Welfare Industry （Meteorology） （GYHY201506012）.
文摘The Coupled Model Intercomparison Project （CMIP） is an international community-based infrastructure that supports climate model intercomparison, climate variability, climate prediction, and climate projection. Improving the performance of climate models over East Asia and the western North Pacific has been a challenge for the climate-modeling community. In this paper, we provide a synthesis robustness analysis of the climate models participating in CMIP-Phase 5 （CMIP5）. The strengths and weaknesses of the CMIP5 models are assessed from the perspective of climate mean state, interannual variability, past climate change during the mid-Pliocene （MP） and the last millennium, and climate projection. The added values of regional climate models relative to the driving global climate models are also assessed. Although an encouraging increase in credibility and an improvement in the simulation of mean states, interannual variability, and past climate changes are visible in the progression from CMIP3 to CMIPS, some previously noticed biases such as the ridge position of the western North Pacific subtropical high and the associated rainfall bias are still evident in CMIP5 models. Weaknesses are also evident in simulations of the interannual amplitude, such as El Nino- Southern Oscillation （ENSO）-monsoon relationships. Coupled models generally show better results than standalone atmospheric models in simulating both mean states and interannual variability. Multi-model intercomparison indicates significant uncertainties in the future projection of climate change, although precipitation increases consistently across models constrained by the Clausius-Clapeyron relation. Regional ocean-atmosphere coupled models are recommended for the dynamical downscaling of climate change oroiections over the East Asia-western North Pacific domain.
基金supported by the Major State Basic Research Development Program of China (973 Program) (Grant No. 2010CB950103)National Natural Science Foundation of China (Grant No. 41071127)Strategic Project of Science and Technology of the Chinese Academy of Sciences (Grant No. XDA05080102)
文摘The occurrence of bumper or poor grain harvests in ancient China plays an important role in explaining how past climate changes affected the economy.Because of the lack of long-term continuous and high-resolution quantitative data for reconstructing the series of grain harvests in ancient China,understanding of the impacts and mechanisms involved in climate change is limited.This study presents a method designed for reconstructing grain harvest series by quantifying grain output levels based on the descriptions in historical documents.The method involves setting the grain output level for each year based on very specific meanings of different words,calculating a yield index based on the structure of each level and assessing grain yields(bumper or poor harvests)every 10 years.First,1636 records related to grain yields(including crop yields,food security,agricultural disasters,grain prices,grain storage and people's livelihoods)for each year were retrieved from history books called the Twenty-Four Histories.Second,using this method,a 10-year resolution graded grain harvest series from the Western Han Dynasty to the Five Dynasties(206 BC–960 AD)is reconstructed.Finally,the relationship between the variations in temperature and precipitation and the fluctuation of grain yields is examined.The results show that from the Western Han Dynasty to the Five Dynasties,bumper,average and poor harvest decades accounted for 33.3%,39.3%and 27.4%of the 1,166-year period,respectively.The grain yields during 206 BC–960 AD can be divided into three stages:a period of bumper harvests during 206–51 BC,poor harvests during 50 BC–590 AD and bumper harvests during 591–960 AD.Bumper harvest decades typically experienced a warm climate with normal or high levels of precipitation,while poor harvest decades had a cold and dry climate.A positive correlation was found between temperature and grain yield because a warm climate allows a full use of resources.The observed relationship between precipitation and grain yield indicated that both flooding and droughts cause poor harvests,which confirms that agricultural production in the monsoon climate of eastern China is greatly impacted by conditions of limited heat and extreme precipitation.
基金Supported jointly by the National Basic Research Program of China 973 Program under Grant No.2005CB321703the NSFC Innovation Research Group Fund under Grant No.40821092.
文摘This paper gives a definition of earth system model and shows three development phases of it, including physical climate system model, earth climate system model, and earth system model, based on an inves- tigation of climate system models in the world. It provides an expatiation on the strategic significance of future development of earth system model, an introduction of some representative scientific research plans on development of earth system model home and abroad, and a review of its status and trends based on the models of the fourth assessment report （AR4） ofthe Intergovernmental Panel on Climate Change （IPCC）. Some suggestions on future development of earth system model in China are given, which are expected to be helpful to advance the development.
