BACKGROUND Appropriate care for individuals who attempt suicide and are admitted to the emergency department(ED)can prevent future suicidal behavior.It is vital to understand their sociodemographic characteristics and...BACKGROUND Appropriate care for individuals who attempt suicide and are admitted to the emergency department(ED)can prevent future suicidal behavior.It is vital to understand their sociodemographic characteristics and the effects of targeted psychological care.AIM To analyze sociodemographic characteristics of suicide attempters treated in the ED and evaluate the efficacy of psychological care.METHODS Data from 239 suicide attempters treated in the ED of the Central Hospital of Enshi Tujia and Miao Autonomous Prefecture(Hubei Province,China)between January 2021 and February 2025 were divided into 2:Control(n=108)and psychological care(n=131).The demographic characteristics and effects of the psychological care were analyzed.RESULTS The mean(±SD)age of the 239 patients[114 male(47.7%),125 female(52.3%)]was 26.25±9.3 years,of whom 122(45.2%)were single,117(48.9%)were married,and 106(44.4%)had secondary education.Thirty-eight(15.9%)patients had suicidal intent,with a mean of 1.26±0.59 suicide attempts each.Twenty-two(9.21%)patients had a family history of suicide,while 8(3.34%)had a family history of suicide attempt(s).Before intervention,mean Suicidal Intent Scale scores in the psychological nursing and control groups were 21.57±5.28 and 19.86±5.92,respectively(P>0.05).After 1 month of nursing intervention,the respective scores were 10.09±1.11 and 16.48±0.87(P<0.001);and the re-suicide rates were 11.45%(15/131)and 24.07%(26/108)(P<0.001).CONCLUSION Psychological care significantly reduces suicide risk;EDs should provide comprehensive mental health care.展开更多
Atrial fibrillation(AF)/atrial flutter(AFL)is the most common sustained cardiac arrhythmia.The known risk factors for developing AF/AFL include age,structural heart disease,hypertension,diabetes mellitus,or hyperthyro...Atrial fibrillation(AF)/atrial flutter(AFL)is the most common sustained cardiac arrhythmia.The known risk factors for developing AF/AFL include age,structural heart disease,hypertension,diabetes mellitus,or hyperthyroidism.This study aims to attribute the trends in AF/AFL-related mortalities over the past two decades 1999-2020 concerning race and sex and disparity among them.To the best of our knowledge,this is the first study that estimates the trends and mortality due to AF/AFL from 1999-2020 in older adults in the United States.In this 21-year analysis of mortality data,we found a constant increase in mortality rates due to AF/AFL in older adults.From 1999 to 2020,the overall mortality in older adults aged 65 and above,regardless of sex and race,is found to be almost doubled i.e.about a 50.2%increase in the number of deaths due to AF/AFL.Furthermore,other confounding risk factors such has obesity,prior myocardial infarction,inflammation,hypertension,birth weight,diabetes mellitus,hyperthyroidism,hormone replacement therapy in menopausal women increases the risk in the occurrence or recurrent occurrence of AF.展开更多
Preserving genetic diversity is crucial for the long-term survival of wild plant species,yet many remain at risk of genetic erosion due to small population sizes and habitat fragmentation.Here,we present a comparative...Preserving genetic diversity is crucial for the long-term survival of wild plant species,yet many remain at risk of genetic erosion due to small population sizes and habitat fragmentation.Here,we present a comparative genomic study of the critically endangered Oreocharis esquirolii(Gesneriaceae)and its widespread congener O.maximowiczii.We assembled and annotated chromosome-level reference genomes for both species and generated whole-genome resequencing data from 28 O.esquirolii and 79 O.maximowiczii individuals.Our analyses reveal substantially lower genetic diversity and higher inbreeding in O.esquirolii,despite its overall reduced mutational burden.Notably,O.esquirolii exhibits an elevated proportion of strongly deleterious mutations relative to O.maximowiczii,suggesting that limited opportunities for purging have allowed these variants to accumulate.These contrasting genomic profileslikely reflectdivergent demographic histories,with O.esquirolii having experienced severe bottlenecks and protracted population decline.Collectively,our findingshighlight the critically endangered status of O.esquirolii,characterized by diminished genetic diversity,pronounced inbreeding,and reduced ability to eliminate deleterious alleles.This study provides valuable genomic resources for the Gesneriaceae family and underscores the urgent need for targeted conservation measures,including habitat protection and ex situ preservation efforts,to mitigate the extinction risk facing O.esquirolii and potentially other threatened congeners.展开更多
Cropland abandonment has been a widespread phenomenon in mountainous areas due to the increasing number of natural disasters and the massive migration of rural labor in the process of rapid urbanization.Land transfer ...Cropland abandonment has been a widespread phenomenon in mountainous areas due to the increasing number of natural disasters and the massive migration of rural labor in the process of rapid urbanization.Land transfer is a crucial prerequisite for ensuring food security and fostering rural revitalization.How to promote land transfer in mountainous areas remains a challenging but important task.Nevertheless,there is a dearth of research examining land transfers among farm households that specifically address mountainous regions,and the influence of grassroots governance and geographic location has not been thoroughly elucidated within this particular context.Based on 895household samples collected in Dabie Mountainous Area in China,this study employs binary and ordinal logistic regression models to provide a more comprehensive analysis on land transfers among rural households and the determinants,including the decision to transfer land,the existence of land transfer rents,the channel of land transfer,the duration of the transfer,the pre-transfer cultivation situation,and the level of satisfaction with the land transfer rent.The findings reveal that grassroots governance,geographic location,livelihood capital,and demographic factors significantly influence land transfers among rural households.Specifically,villagers'public participation positively affects land transfer participation(β=0.235,p<0.05),while the operation of village rules and regulations negatively impacts it(β=-0.296,p<0.05).Village cadre satisfaction positively influences both land transfer rent(β=0.274,p<0.05)and rent satisfaction(β=0.303,p<0.05).Improved civil relations in the village correlate with lower land transfer rent(β=-0.511,p<0.05),while a better social atmosphere is associated with higher satisfaction with transfer rent(β=0.575,p<0.01).Households at higher elevations tend to prefer government-mediated land transfers with longer durations.The distances to the township and county centers have contrasting effects on land transfer rent,but their impacts on participation in land transfer,choice of transfer channel,and duration are consistent.The study also found that different types of livelihood capital,as well as the demographic characteristics of households,significantly affect various aspects of land transfer.These empirical findings can inform policymaking to promote more efficient land transfers in mountainous region.展开更多
BACKGROUND Ovarian carcinoma has the highest mortality rate among all gynecological cancers.Several reproductive and hormonal risk factors,including early menarche,late menopause,limited use of oral contraceptives,and...BACKGROUND Ovarian carcinoma has the highest mortality rate among all gynecological cancers.Several reproductive and hormonal risk factors,including early menarche,late menopause,limited use of oral contraceptives,and a low pregnancy rate,have been identified as contributors to the increased susceptibility to ovarian cancer.Advancements in cancer therapy over the past century,including the emergence of precision oncology,underscore the importance of early detection and tailored interventions,factors particularly critical in ovarian cancer,where late-stage diagnosis remains a persistent barrier to survival.This challenge is compounded by the lack of a universally endorsed screening program,resulting in late-stage identification and widespread metastasis.AIM To evaluate demographic differences in ovarian cancer-related mortality from 1999 to 2020 among adult females aged≥25 years within the United States.METHODS Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database was used to collect de-identified death certificate data for malignant neoplasm of the ovaries related deaths in female adults aged 25 years and older from the year 1999 to 2020.Crude mortality rates and age-adjusted mortality rates(AAMRs)per 100000 people were calculated.Join point regression program was used to assess annual percent changes in mortality trends,with statistical significance set at P value<0.05.RESULTS Between 1999 and 2020,337619 deaths due to ovarian cancer occurred among United States females aged 25 to>85.The AAMR decreased from 14.62 in 1999 to 10.15 in 2020,with significant declines across various demographics.The AAMRs were highest among non-Hispanic White women,i.e.,13.53.Based on region,they were the highest in the Northeast(13.06)and Midwest(12.94).The steepest decline was observed in metropolitan areas as compared to nonmetropolitan ones.The study highlights significant progress in reducing ovarian cancer mortality across age,race/ethnicity,and geographic regions during this period.CONCLUSION The mortality trends for ovarian carcinoma patients showed an overall decrease,with the highest mortality rates observed among older individuals(65 to>85 years)and non-Hispanic Whites.These disparities underscore the need for equitable healthcare access and targeted policy interventions.展开更多
Hu sheep is an indigenous breed from the Taihu Lake Plain in China,known for its high fertility.Although Hu sheep belong to the Mongolian group,their demographic history and genetic architecture remain inconclusive.He...Hu sheep is an indigenous breed from the Taihu Lake Plain in China,known for its high fertility.Although Hu sheep belong to the Mongolian group,their demographic history and genetic architecture remain inconclusive.Here,we analyze 697 sheep genomes from representatives of Mongolian sheep breeds.Our study suggests that the ancestral Hu sheep first separated from the Mongolian group approximately 3000 years ago.As Hu sheep migrated from the north and flourished in the Taihu Lake Plain around 1000 years ago,they developed a unique genetic foundation and phenotypic characteristics,which are evident in the genomic footprints of selective sweeps and structural variation landscape.Genes associated with reproductive traits(BMPR1B and TDRD10)and horn phenotype(RXFP2)exhibit notable selective sweeps in the genome of Hu sheep.A genome-wide association analysis reveals that structural variations at LOC101110773,MAST2,and ZNF385B may significantly impact polledness,teat number,and early growth in Hu sheep,respectively.Our study offers insights into the evolutionary history of Hu sheep and may serve as a valuable genetic resource to enhance the understanding of complex traits in Hu sheep.展开更多
This study examines how demographic factors shape engagement with virtual cultural communities and awareness of emerging economic models.Using survey data from 202 participants,descriptive statistics,independent sampl...This study examines how demographic factors shape engagement with virtual cultural communities and awareness of emerging economic models.Using survey data from 202 participants,descriptive statistics,independent samples t-tests,and One-way Analysis of Variance(ANOVA)with Least Significant Difference(LSD)post-hoc analyses revealed significant influences of age,education,and occupation.No significant gender differences were found.Individuals aged 26-45 demonstrated higher virtual community participation(F=3.439,p=0.01)and emerging model awareness(F=2.834,p=0.026)than younger cohorts(18-25 years and below).Respondents with postgraduate education exhibited superior understanding of emerging economic models(F=3.296,p=0.022)and their nexus with cultural values(F=6.196,p<0.001)compared to those with lower educational attainment.Significant occupational variations existed in virtual participation(F=4.001,p=0.008)and economic model awareness(F=5.611,p=0.001),with enterprise employees and civil servants scoring higher than students and freelancers.These findings underscore the critical roles of life stage,educational investment,and professional context in shaping digital cultural behaviors and economic cognition,offering valuable insights for platform design,educational strategies,and policy development in the digital cultural economy.展开更多
Climate change is expected to alter the popu-lation dynamics of pioneer tree species and their planned use in sustainable forest management,but we have a lim-ited understanding of how their demographic rates change in...Climate change is expected to alter the popu-lation dynamics of pioneer tree species and their planned use in sustainable forest management,but we have a lim-ited understanding of how their demographic rates change in response to climate changes during ecological restora-tion.Based on 12 years of demographic data for a pioneer tree species(Pinus massoniana)censused in three plots that correspond to three stages of ecological restoration in south-eastern China.We built integral projection models(IPMs)to assess vital rates(survival,growth,reproduction)and population growth in each plot,then evaluated demographic changes to simulated changes in seasonal mean temperature and precipitation in the current and previous census period.The plot representing the medium restoration stage had the highest population growth rate(λ=0.983).Mean population survival probability increased with ecological restoration,and reproduction probability was significantly suppressed at the high restoration stage.Survival is always the most important vital rate forλ,and climate affectsλprimarily via survival at each restoration stage.The current spring tem-perature was the most critical climate variable forλin the low and medium restoration stages,and previous summer temperature was most critical in the high restoration stage.Simulated warming leads to a decrease in the stochastic population growth rate(λ_(s))of P.massoniana in every stage.These findings suggest that during ecological restoration,P.massoniana responds to habitat change via modified demo-graphic performance,thus altering its response to climate change.Despite diverse responses to climate change,the persistence of P.massoniana populations is facing a wide-spread threat of warming states at each restoration stages.展开更多
A great discovery made by H. von Foerster, P. M. Mora and L. W. Amiot was published in a 1960 issue of “Science”. The authors showed that existing data for calculating the Earth’s population in the new era (from 1 ...A great discovery made by H. von Foerster, P. M. Mora and L. W. Amiot was published in a 1960 issue of “Science”. The authors showed that existing data for calculating the Earth’s population in the new era (from 1 to 1958) could be described with incredibly high proximity by a hyperbolic function with the point of singularity on 13 November 2026. Thus, empirical regularity of the rise of the human population was established, which was marked by explosive demographic growth in the 20<sup>th</sup> century when during only one century it almost quadrupled: from 1.656 billion in 1900 to 6.144 billion in 2000. Nowadays, the world population has already overcome 7.8 billion people. Immediately after 1960, an active search for phenomenological models began to explain the mechanism of the hyperbolic population growth and the following demographic transition designed to stabilize its population. A significant role in explaining the mechanism of the hyperbolic growth of the world population was played by S. Kuznets (1960) and E. Boserup (1965), who found out that the rates of technological progress historically increased in proportion to the Earth’s population. It meant that the growth of the population led to raising the level of life-supporting technologies, and the latter in its turn enlarged the carrying capacity of the Earth, making it possible for the world population to expand. Proceeding from the information imperative, we have developed the model of the demographic dynamics for the 21<sup>st</sup> century for the first time. The model shows that with the development and spread of Intelligent Machines (IM), the number of the world population reaching a certain maximum will then irreversibly decline. Human depopulation will largely touch upon the most developed countries, where IM is used intensively nowadays. Until a certain moment in time, this depopulation in developed countries will be compensated by the explosive growth of the population in African countries located south of the Sahara. Calculations in our model reveal that the peak of the human population of 8.52 billion people will be reached in 2050, then it will irreversibly go down to 7.9 billion people by 2100, if developed countries do not take timely effective measures to overcome the process of information depopulation.展开更多
Given the great strides that China＇s education sector has made in recent decades, it can be expected that the overall workforce quality of exiting China＇s labor market in coming one or two decades will be relatively...Given the great strides that China＇s education sector has made in recent decades, it can be expected that the overall workforce quality of exiting China＇s labor market in coming one or two decades will be relatively low, while the overall quality of workforce newly entering into China＇s labor market will be high. As the new, bettereducated generation takes over, China＇s workforce quality will be vastly improved. This in turn will promote economic growth. We refer to economic growth arising from improved workforce quality as qualitative demographic dividend. Using the computable general equilibrium （CGE） model, this paper investigates the relationship between workforce quality improvements and economic growth. According to the model＇s results, an improvement in workforce quality will raise the economic growth rate by about two percentage points per annum between 2016 and 2020 and by 10 percentage points cumulatively by 2020. In other words, GDP will be 1.1 times the level of baseline GDP by 2020 due to the improved education levels. Given different production functions across sectors, the improvement of workforce quality will affect different sectors in different ways. On the whole, the improvement of workforce quality is more favorable to the development of capital-intensive sectors and sectors with rapid technology progress. According to this paper, considering the improvement of workforce quality, we cannot conclude that China＇s potential economic growth rate has already begun to decline. Despite diminishing conventional quantitative demographic dividends, China ＂s qualitative demographic dividends will keep rising. Qualitative demographic dividends will further push forward China＇s industrial restructuring and the strategic transition of industrial competitiveness from quantitative to qualitative and from an extensive to an intensive pattern of development.展开更多
[Objective] The aim was to analyze the phenomenon of employment diffi- culty and labor shortage, and to reveal the influencing factors of employment difli- culty and labor shortage. [Method] On the basis of the econom...[Objective] The aim was to analyze the phenomenon of employment diffi- culty and labor shortage, and to reveal the influencing factors of employment difli- culty and labor shortage. [Method] On the basis of the economic principle of popu- lation dividend, the use of human resources and natural resource constraints The IS-LM model describes these two states. [Results] The resource constraints have a ＂squeeze＂ effect on the demographic dividend, and employment pressure is shown in terms of the population opportunity window; the labor market segmentation, the ir- rational industrial structure, the backward curriculum and employment concept are the main factors affecting employment and labor shortage. [Conclusion] The way to solve this dilemma must be removed from the division of labor market, the adjust- ment of industrial structure, the setting of university specialty, the change of em- ployment concept of university graduates as well as the improvement of the quality of labor.展开更多
This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the ...This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the direction of demographic transition and whether or not it has finished. Apart from establishing new theories of demographic transition and the trasition of demographic structure, this paper differentiates the concepts of ＂relative surplus population＂ and ＂relative suitable population,＂ and ＂relative insufficient population＂ and identifies key demographic differences along the way. In doing so, this paper argues that China＇s demographic strueture is undergoing a process of rebalancing.展开更多
Worldwide, the incidence of birth defects in low-income countries is 6.42%, while in middle-income and high-income countries it is 5.57% and 4.72%, respectively;approximately 303, 000 newborns die from birth defects e...Worldwide, the incidence of birth defects in low-income countries is 6.42%, while in middle-income and high-income countries it is 5.57% and 4.72%, respectively;approximately 303, 000 newborns die from birth defects each year. In China, the incidence of birth defects is about 5.6%, and around 8.14 million people have congenital disabilities, accounting for 9.6% of total disabled people[1]. Birth defect remains a major clinical and public health challenge because of its high fatality rate and protracted and severe sequela.展开更多
With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how ...With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how it responds to demographic dynamics,particularly in emerging economies like China.Using the two-stage Quadratic Almost Demand System(QUAIDS)model,this study empirically examines the impact of demographic dynamics on food consumption and its environmental outcomes based on the provincial data from 2000 to 2020 in China.Under various scenarios,according to changes in demographics,we extend our analysis to project the long-term trend of food consumption and its environmental impacts,including greenhouse gas(GHG)emissions,water footprint(WF),and land appropriation(LA).The results reveal that an increase in the proportion of senior people significantly decreases the consumption of grain and livestock meat and increases the consumption of poultry,egg,and aquatic products,particularly for urban residents.Moreover,an increase in the proportion of males in the population leads to higher consumption of poultry and aquatic products.Correspondingly,in the current scenario of an increased aging population and sex ratio,it is anticipated that GHG emissions,WF,and LA are likely to decrease by 1.37,2.52,and 3.56%,respectively.More importantly,in the scenario adhering to the standards of nutritional intake according to the Dietary Guidelines for Chinese Residents in 2022,GHG emissions,WF,and LA in urban areas would increase by 12.78,20.94,and 18.32%,respectively.Our findings suggest that changing demographics should be considered when designing policies to mitigate the diet-environment-health trilemma and achieve sustainable food consumption.展开更多
To identify the determinant of the occurrence of IUD expulsion Materials & Methods Based on 25 733 IUD uses from the Chinese Two per Thousand Fertility Survey data, this study examines the patterns and differe...To identify the determinant of the occurrence of IUD expulsion Materials & Methods Based on 25 733 IUD uses from the Chinese Two per Thousand Fertility Survey data, this study examines the patterns and differentials of IUD expulsion rate by characteristics of women, and identifies the socio demographic determinants of IUD expulsion. A Life Table method was used to calculate the cumulative expulsion rate and a random effects discrete time survival model was employed to assess the impact of potential determinants simultaneously on the risk of expelling an IUD. Results Three major findings are observed in this study. First, IUD expulsion was the second main reason, after pregnancy during IUD use, for IUD discontinuation during the first four years of IUD insertion; the expulsion rates were 6.4%, 9.1%, 10.8 %, and 12.0% at 12, 24, 36 and 48 months, respectively. Second, there was a clustering of IUD expulsion: some women experienced repeated IUD expulsions. Third, some socio demographic characteristics and fertility history were associated with the occurrence of IUD expulsion. In particular, the expulsion rate was high among young women, among those with two or more children and among those living in rural areas. Conclusion The above mentioned factors shoald be addressed in order to decrease the IUD expulsion rate and enhance the reprocluctive he alth of women.展开更多
The objective of social development is to construct a harmonious society.In China,the key to a harmonious society is the happiness of more than 900 million farmers living in the rural areas.This study aimed to measure...The objective of social development is to construct a harmonious society.In China,the key to a harmonious society is the happiness of more than 900 million farmers living in the rural areas.This study aimed to measure rural residents' subjective well-being(SWB) through the day reconstruction method,as well as to analyze SWB's influencing factors through a variety of statistical methods.The results showed that the average U index was 12.79%,indicating that respondents were unhappy 12.79% of the time.Twenty-seven percent of the population had a U index greater than 0,with the average value being 47%,indicating that these people were unhappy 47% of the time.The study also found that SWB varied according to the characteristics of the respondents.Logistic regression analysis showed that social and demographic factors,including age,education,county,household size,generation number,per capita income,migration status and social networking,which significantly affected rural residents' SWB.The size of the impact varied with the different factors.展开更多
Drawn on the data collected by surveying 1 340 urban households from six cities in China, this paper estimates the impacts of demographic structure and population aging on household meat consumption, by jointly consid...Drawn on the data collected by surveying 1 340 urban households from six cities in China, this paper estimates the impacts of demographic structure and population aging on household meat consumption, by jointly considering meat consumed at home and away from home. Based on the trajectories of population, a simple simulation on meat demand trend in China is conducted subsequently. The results suggest： 1） Meat consumed away from home averagely accounts for near 30% of household total meat consumption in terms of quantity, so that its omission likely leads to a significant underestimate of total meat consumption and misunderstanding the driving forces; 2） population aging significantly and negatively affects per capita meat consumption, suggesting that the expected meat demand in China without considering population aging will be overestimated. The findings from this study have important implications for better understanding the relative issues on China＇s meat consumption under the situation of population aging.展开更多
Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China...Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China were selected as samples in this study using a multistage cluster random sampling method.The basic information questionnaire and Constitution in Chinese Medicine Questionnaire(Elderly Edition)were used.Descriptive statistical analysis,chi-squared tests,and binary logistic regression analysis were used.Results: The single balanced constitution(BC)accounted for 23.9%.The results of the major TCM constitution types showed that BC(43.2%)accounted for the largest proportion and unbalanced constitutions ranged from 0.9%to 15.7%.East China region(odds ratio[OR]=2.097;95%confidence interval[CI],1.912 to 2.301),married status(OR=1.341;95%CI,1.235 to 1.457),and managers(OR=1.254;95%CI,1.044 to 1.505)were significantly associated with BC.Age>70 years was associated with qi-deficiency constitution and blood stasis constitution(BSC).Female sex was significantly associated with yang-deficiency constitution(OR=1.646;95%CI,1.52 to 1.782).Southwest region was significantly associated with phlegm-dampness constitution(OR=1.809;95%CI,1.569 to 2.086).North China region was significantly associated with inherited special constitution(OR=2.521;95%CI,1.569 to 4.05).South China region(OR=2.741;95%CI,1.997 to 1.3.763),Central China region(OR=8.889;95%CI,6.676 to 11.835),senior middle school education(OR=2.442;95%CI,1.932 to 3.088),and managers(OR=1.804;95%CI,1.21 to 2.69)were significantly associated with BSC.Conclusions: This study defined the distribution characteristics and demographic factors of TCM constitution in the elderly population.Adjusting and improving unbalanced constitutions,which are correlated with diseases,can help promote healthy aging through the scientific management of these demographic factors.展开更多
Background:The first three censuses of the 50-ha plot at Barro Colorado Island spanned an unusually harsh dry season during the 1983 El Nitro.By the early 1990s,we had documented increases in tree mortality,tree growt...Background:The first three censuses of the 50-ha plot at Barro Colorado Island spanned an unusually harsh dry season during the 1983 El Nitro.By the early 1990s,we had documented increases in tree mortality,tree growth,and large population fluctuations of many species during the 1982-1985 census interval.At the time,we asserted that increasing drought frequency would greatly affect the forest.With the benefit of five more censuses at Barro Colorado from 1995-2015,we can now put the 1980 conditions in a longer perspective and test the hypothesis that increasing droughtiness has continued to change the forest.Methods:A 50-ha forest plot on Barro Colorado Island was censused eight times,in 1982 and every five years since 1985.All free-standing woody stems were measured,mapped,and identified in each census.Results:1)The period 1982-1992 included several extreme dry seasons,not just 1983,but since then there have been few such droughts.2)Dbh growth declined from a peak in the early 1980s to its lowest in the early 1990s.From 1995-2015 it increased slightly,but not returning to the initial peak.Nearly every species and all dbh categories followed the same pattern.3)The elevated stand-wide mortality rate of large trees during the 1982-1985 drought has not returned,and most individual species showed the same pattern of elevated mortality in the 1980s followed by low and fairly stable mortality after 1990.4)Sapling mortality declined after 198,5,but rose again in the late-90s,so the 1980s drought period no longer looks unusual.Mortality of individual species'saplings fluctuated erratically,including cases where mortality during the drought was lower than after.5)Population sizes of individual species fluctuated in all possible directions.Some species declined precipitously during the drought,then recovered,but others did not recover.Other species increased in abundance during the drought.Conclusions"Droughts of the 1980s elevated tree growth and mortality at Barro Colorado,but since 1990,demographic rates have remained lower,paralleling a moderate climate with few severe droughts after 1990.Moisture-demanding species suffered during the drought,but many have since recovered.We do not know how often such drought periods recur.Moreover,many species'abundances fluctuated over 35 years with no known cause.展开更多
文摘BACKGROUND Appropriate care for individuals who attempt suicide and are admitted to the emergency department(ED)can prevent future suicidal behavior.It is vital to understand their sociodemographic characteristics and the effects of targeted psychological care.AIM To analyze sociodemographic characteristics of suicide attempters treated in the ED and evaluate the efficacy of psychological care.METHODS Data from 239 suicide attempters treated in the ED of the Central Hospital of Enshi Tujia and Miao Autonomous Prefecture(Hubei Province,China)between January 2021 and February 2025 were divided into 2:Control(n=108)and psychological care(n=131).The demographic characteristics and effects of the psychological care were analyzed.RESULTS The mean(±SD)age of the 239 patients[114 male(47.7%),125 female(52.3%)]was 26.25±9.3 years,of whom 122(45.2%)were single,117(48.9%)were married,and 106(44.4%)had secondary education.Thirty-eight(15.9%)patients had suicidal intent,with a mean of 1.26±0.59 suicide attempts each.Twenty-two(9.21%)patients had a family history of suicide,while 8(3.34%)had a family history of suicide attempt(s).Before intervention,mean Suicidal Intent Scale scores in the psychological nursing and control groups were 21.57±5.28 and 19.86±5.92,respectively(P>0.05).After 1 month of nursing intervention,the respective scores were 10.09±1.11 and 16.48±0.87(P<0.001);and the re-suicide rates were 11.45%(15/131)and 24.07%(26/108)(P<0.001).CONCLUSION Psychological care significantly reduces suicide risk;EDs should provide comprehensive mental health care.
文摘Atrial fibrillation(AF)/atrial flutter(AFL)is the most common sustained cardiac arrhythmia.The known risk factors for developing AF/AFL include age,structural heart disease,hypertension,diabetes mellitus,or hyperthyroidism.This study aims to attribute the trends in AF/AFL-related mortalities over the past two decades 1999-2020 concerning race and sex and disparity among them.To the best of our knowledge,this is the first study that estimates the trends and mortality due to AF/AFL from 1999-2020 in older adults in the United States.In this 21-year analysis of mortality data,we found a constant increase in mortality rates due to AF/AFL in older adults.From 1999 to 2020,the overall mortality in older adults aged 65 and above,regardless of sex and race,is found to be almost doubled i.e.about a 50.2%increase in the number of deaths due to AF/AFL.Furthermore,other confounding risk factors such has obesity,prior myocardial infarction,inflammation,hypertension,birth weight,diabetes mellitus,hyperthyroidism,hormone replacement therapy in menopausal women increases the risk in the occurrence or recurrent occurrence of AF.
基金supported by National Key R&D Program of China(2024YFF1307400)Guangdong S&T Program(2022B1111230001).
文摘Preserving genetic diversity is crucial for the long-term survival of wild plant species,yet many remain at risk of genetic erosion due to small population sizes and habitat fragmentation.Here,we present a comparative genomic study of the critically endangered Oreocharis esquirolii(Gesneriaceae)and its widespread congener O.maximowiczii.We assembled and annotated chromosome-level reference genomes for both species and generated whole-genome resequencing data from 28 O.esquirolii and 79 O.maximowiczii individuals.Our analyses reveal substantially lower genetic diversity and higher inbreeding in O.esquirolii,despite its overall reduced mutational burden.Notably,O.esquirolii exhibits an elevated proportion of strongly deleterious mutations relative to O.maximowiczii,suggesting that limited opportunities for purging have allowed these variants to accumulate.These contrasting genomic profileslikely reflectdivergent demographic histories,with O.esquirolii having experienced severe bottlenecks and protracted population decline.Collectively,our findingshighlight the critically endangered status of O.esquirolii,characterized by diminished genetic diversity,pronounced inbreeding,and reduced ability to eliminate deleterious alleles.This study provides valuable genomic resources for the Gesneriaceae family and underscores the urgent need for targeted conservation measures,including habitat protection and ex situ preservation efforts,to mitigate the extinction risk facing O.esquirolii and potentially other threatened congeners.
基金supported by the National Natural Science Foundation of China(Grant Nos.42371315,41901213)the Humanities and Social Sciences General Research Program of the Ministry of Education(Grant No.23YJC790141)。
文摘Cropland abandonment has been a widespread phenomenon in mountainous areas due to the increasing number of natural disasters and the massive migration of rural labor in the process of rapid urbanization.Land transfer is a crucial prerequisite for ensuring food security and fostering rural revitalization.How to promote land transfer in mountainous areas remains a challenging but important task.Nevertheless,there is a dearth of research examining land transfers among farm households that specifically address mountainous regions,and the influence of grassroots governance and geographic location has not been thoroughly elucidated within this particular context.Based on 895household samples collected in Dabie Mountainous Area in China,this study employs binary and ordinal logistic regression models to provide a more comprehensive analysis on land transfers among rural households and the determinants,including the decision to transfer land,the existence of land transfer rents,the channel of land transfer,the duration of the transfer,the pre-transfer cultivation situation,and the level of satisfaction with the land transfer rent.The findings reveal that grassroots governance,geographic location,livelihood capital,and demographic factors significantly influence land transfers among rural households.Specifically,villagers'public participation positively affects land transfer participation(β=0.235,p<0.05),while the operation of village rules and regulations negatively impacts it(β=-0.296,p<0.05).Village cadre satisfaction positively influences both land transfer rent(β=0.274,p<0.05)and rent satisfaction(β=0.303,p<0.05).Improved civil relations in the village correlate with lower land transfer rent(β=-0.511,p<0.05),while a better social atmosphere is associated with higher satisfaction with transfer rent(β=0.575,p<0.01).Households at higher elevations tend to prefer government-mediated land transfers with longer durations.The distances to the township and county centers have contrasting effects on land transfer rent,but their impacts on participation in land transfer,choice of transfer channel,and duration are consistent.The study also found that different types of livelihood capital,as well as the demographic characteristics of households,significantly affect various aspects of land transfer.These empirical findings can inform policymaking to promote more efficient land transfers in mountainous region.
文摘BACKGROUND Ovarian carcinoma has the highest mortality rate among all gynecological cancers.Several reproductive and hormonal risk factors,including early menarche,late menopause,limited use of oral contraceptives,and a low pregnancy rate,have been identified as contributors to the increased susceptibility to ovarian cancer.Advancements in cancer therapy over the past century,including the emergence of precision oncology,underscore the importance of early detection and tailored interventions,factors particularly critical in ovarian cancer,where late-stage diagnosis remains a persistent barrier to survival.This challenge is compounded by the lack of a universally endorsed screening program,resulting in late-stage identification and widespread metastasis.AIM To evaluate demographic differences in ovarian cancer-related mortality from 1999 to 2020 among adult females aged≥25 years within the United States.METHODS Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database was used to collect de-identified death certificate data for malignant neoplasm of the ovaries related deaths in female adults aged 25 years and older from the year 1999 to 2020.Crude mortality rates and age-adjusted mortality rates(AAMRs)per 100000 people were calculated.Join point regression program was used to assess annual percent changes in mortality trends,with statistical significance set at P value<0.05.RESULTS Between 1999 and 2020,337619 deaths due to ovarian cancer occurred among United States females aged 25 to>85.The AAMR decreased from 14.62 in 1999 to 10.15 in 2020,with significant declines across various demographics.The AAMRs were highest among non-Hispanic White women,i.e.,13.53.Based on region,they were the highest in the Northeast(13.06)and Midwest(12.94).The steepest decline was observed in metropolitan areas as compared to nonmetropolitan ones.The study highlights significant progress in reducing ovarian cancer mortality across age,race/ethnicity,and geographic regions during this period.CONCLUSION The mortality trends for ovarian carcinoma patients showed an overall decrease,with the highest mortality rates observed among older individuals(65 to>85 years)and non-Hispanic Whites.These disparities underscore the need for equitable healthcare access and targeted policy interventions.
基金supported by grants from the Zhejiang Science and Technology Department Project(2023C04004)Zhejiang Science and Technology Major Program on Agricultural New Variety Breeding(2021C02068-6)+2 种基金Department of Science Technology of Huzhou City(2023GZ33)Zhejiang Team Technology Ambassador Project(Tongxiang)the National Natural Science Foundation of China(32172724).
文摘Hu sheep is an indigenous breed from the Taihu Lake Plain in China,known for its high fertility.Although Hu sheep belong to the Mongolian group,their demographic history and genetic architecture remain inconclusive.Here,we analyze 697 sheep genomes from representatives of Mongolian sheep breeds.Our study suggests that the ancestral Hu sheep first separated from the Mongolian group approximately 3000 years ago.As Hu sheep migrated from the north and flourished in the Taihu Lake Plain around 1000 years ago,they developed a unique genetic foundation and phenotypic characteristics,which are evident in the genomic footprints of selective sweeps and structural variation landscape.Genes associated with reproductive traits(BMPR1B and TDRD10)and horn phenotype(RXFP2)exhibit notable selective sweeps in the genome of Hu sheep.A genome-wide association analysis reveals that structural variations at LOC101110773,MAST2,and ZNF385B may significantly impact polledness,teat number,and early growth in Hu sheep,respectively.Our study offers insights into the evolutionary history of Hu sheep and may serve as a valuable genetic resource to enhance the understanding of complex traits in Hu sheep.
文摘This study examines how demographic factors shape engagement with virtual cultural communities and awareness of emerging economic models.Using survey data from 202 participants,descriptive statistics,independent samples t-tests,and One-way Analysis of Variance(ANOVA)with Least Significant Difference(LSD)post-hoc analyses revealed significant influences of age,education,and occupation.No significant gender differences were found.Individuals aged 26-45 demonstrated higher virtual community participation(F=3.439,p=0.01)and emerging model awareness(F=2.834,p=0.026)than younger cohorts(18-25 years and below).Respondents with postgraduate education exhibited superior understanding of emerging economic models(F=3.296,p=0.022)and their nexus with cultural values(F=6.196,p<0.001)compared to those with lower educational attainment.Significant occupational variations existed in virtual participation(F=4.001,p=0.008)and economic model awareness(F=5.611,p=0.001),with enterprise employees and civil servants scoring higher than students and freelancers.These findings underscore the critical roles of life stage,educational investment,and professional context in shaping digital cultural behaviors and economic cognition,offering valuable insights for platform design,educational strategies,and policy development in the digital cultural economy.
基金supported by the National Natural Science Foundation of China(grant no.31971638)the Public Welfare Project of Fujian Science and Technology Department(grant no.2024R1002001).
文摘Climate change is expected to alter the popu-lation dynamics of pioneer tree species and their planned use in sustainable forest management,but we have a lim-ited understanding of how their demographic rates change in response to climate changes during ecological restora-tion.Based on 12 years of demographic data for a pioneer tree species(Pinus massoniana)censused in three plots that correspond to three stages of ecological restoration in south-eastern China.We built integral projection models(IPMs)to assess vital rates(survival,growth,reproduction)and population growth in each plot,then evaluated demographic changes to simulated changes in seasonal mean temperature and precipitation in the current and previous census period.The plot representing the medium restoration stage had the highest population growth rate(λ=0.983).Mean population survival probability increased with ecological restoration,and reproduction probability was significantly suppressed at the high restoration stage.Survival is always the most important vital rate forλ,and climate affectsλprimarily via survival at each restoration stage.The current spring tem-perature was the most critical climate variable forλin the low and medium restoration stages,and previous summer temperature was most critical in the high restoration stage.Simulated warming leads to a decrease in the stochastic population growth rate(λ_(s))of P.massoniana in every stage.These findings suggest that during ecological restoration,P.massoniana responds to habitat change via modified demo-graphic performance,thus altering its response to climate change.Despite diverse responses to climate change,the persistence of P.massoniana populations is facing a wide-spread threat of warming states at each restoration stages.
文摘A great discovery made by H. von Foerster, P. M. Mora and L. W. Amiot was published in a 1960 issue of “Science”. The authors showed that existing data for calculating the Earth’s population in the new era (from 1 to 1958) could be described with incredibly high proximity by a hyperbolic function with the point of singularity on 13 November 2026. Thus, empirical regularity of the rise of the human population was established, which was marked by explosive demographic growth in the 20<sup>th</sup> century when during only one century it almost quadrupled: from 1.656 billion in 1900 to 6.144 billion in 2000. Nowadays, the world population has already overcome 7.8 billion people. Immediately after 1960, an active search for phenomenological models began to explain the mechanism of the hyperbolic population growth and the following demographic transition designed to stabilize its population. A significant role in explaining the mechanism of the hyperbolic growth of the world population was played by S. Kuznets (1960) and E. Boserup (1965), who found out that the rates of technological progress historically increased in proportion to the Earth’s population. It meant that the growth of the population led to raising the level of life-supporting technologies, and the latter in its turn enlarged the carrying capacity of the Earth, making it possible for the world population to expand. Proceeding from the information imperative, we have developed the model of the demographic dynamics for the 21<sup>st</sup> century for the first time. The model shows that with the development and spread of Intelligent Machines (IM), the number of the world population reaching a certain maximum will then irreversibly decline. Human depopulation will largely touch upon the most developed countries, where IM is used intensively nowadays. Until a certain moment in time, this depopulation in developed countries will be compensated by the explosive growth of the population in African countries located south of the Sahara. Calculations in our model reveal that the peak of the human population of 8.52 billion people will be reached in 2050, then it will irreversibly go down to 7.9 billion people by 2100, if developed countries do not take timely effective measures to overcome the process of information depopulation.
文摘Given the great strides that China＇s education sector has made in recent decades, it can be expected that the overall workforce quality of exiting China＇s labor market in coming one or two decades will be relatively low, while the overall quality of workforce newly entering into China＇s labor market will be high. As the new, bettereducated generation takes over, China＇s workforce quality will be vastly improved. This in turn will promote economic growth. We refer to economic growth arising from improved workforce quality as qualitative demographic dividend. Using the computable general equilibrium （CGE） model, this paper investigates the relationship between workforce quality improvements and economic growth. According to the model＇s results, an improvement in workforce quality will raise the economic growth rate by about two percentage points per annum between 2016 and 2020 and by 10 percentage points cumulatively by 2020. In other words, GDP will be 1.1 times the level of baseline GDP by 2020 due to the improved education levels. Given different production functions across sectors, the improvement of workforce quality will affect different sectors in different ways. On the whole, the improvement of workforce quality is more favorable to the development of capital-intensive sectors and sectors with rapid technology progress. According to this paper, considering the improvement of workforce quality, we cannot conclude that China＇s potential economic growth rate has already begun to decline. Despite diminishing conventional quantitative demographic dividends, China ＂s qualitative demographic dividends will keep rising. Qualitative demographic dividends will further push forward China＇s industrial restructuring and the strategic transition of industrial competitiveness from quantitative to qualitative and from an extensive to an intensive pattern of development.
基金Supported by the National Social Science Fund of China(13XSH017)~~
文摘[Objective] The aim was to analyze the phenomenon of employment diffi- culty and labor shortage, and to reveal the influencing factors of employment difli- culty and labor shortage. [Method] On the basis of the economic principle of popu- lation dividend, the use of human resources and natural resource constraints The IS-LM model describes these two states. [Results] The resource constraints have a ＂squeeze＂ effect on the demographic dividend, and employment pressure is shown in terms of the population opportunity window; the labor market segmentation, the ir- rational industrial structure, the backward curriculum and employment concept are the main factors affecting employment and labor shortage. [Conclusion] The way to solve this dilemma must be removed from the division of labor market, the adjust- ment of industrial structure, the setting of university specialty, the change of em- ployment concept of university graduates as well as the improvement of the quality of labor.
文摘This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the direction of demographic transition and whether or not it has finished. Apart from establishing new theories of demographic transition and the trasition of demographic structure, this paper differentiates the concepts of ＂relative surplus population＂ and ＂relative suitable population,＂ and ＂relative insufficient population＂ and identifies key demographic differences along the way. In doing so, this paper argues that China＇s demographic strueture is undergoing a process of rebalancing.
基金supported by the National Natural Science Foundation of China [No.81172680]
文摘Worldwide, the incidence of birth defects in low-income countries is 6.42%, while in middle-income and high-income countries it is 5.57% and 4.72%, respectively;approximately 303, 000 newborns die from birth defects each year. In China, the incidence of birth defects is about 5.6%, and around 8.14 million people have congenital disabilities, accounting for 9.6% of total disabled people[1]. Birth defect remains a major clinical and public health challenge because of its high fatality rate and protracted and severe sequela.
基金This work was supported by the Qinchuangyuan Project of Shaanxi Province,China(QCYRCXM-2022-145)the Major Project of the Key Research Base of Humanities and Social Sciences of the Ministry of Education,China(22JJD790052)+1 种基金the Chinese Universities Scientific Fund(Z1010422003)the National Natural Science Foundation of China(72373117).
文摘With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how it responds to demographic dynamics,particularly in emerging economies like China.Using the two-stage Quadratic Almost Demand System(QUAIDS)model,this study empirically examines the impact of demographic dynamics on food consumption and its environmental outcomes based on the provincial data from 2000 to 2020 in China.Under various scenarios,according to changes in demographics,we extend our analysis to project the long-term trend of food consumption and its environmental impacts,including greenhouse gas(GHG)emissions,water footprint(WF),and land appropriation(LA).The results reveal that an increase in the proportion of senior people significantly decreases the consumption of grain and livestock meat and increases the consumption of poultry,egg,and aquatic products,particularly for urban residents.Moreover,an increase in the proportion of males in the population leads to higher consumption of poultry and aquatic products.Correspondingly,in the current scenario of an increased aging population and sex ratio,it is anticipated that GHG emissions,WF,and LA are likely to decrease by 1.37,2.52,and 3.56%,respectively.More importantly,in the scenario adhering to the standards of nutritional intake according to the Dietary Guidelines for Chinese Residents in 2022,GHG emissions,WF,and LA in urban areas would increase by 12.78,20.94,and 18.32%,respectively.Our findings suggest that changing demographics should be considered when designing policies to mitigate the diet-environment-health trilemma and achieve sustainable food consumption.
文摘To identify the determinant of the occurrence of IUD expulsion Materials & Methods Based on 25 733 IUD uses from the Chinese Two per Thousand Fertility Survey data, this study examines the patterns and differentials of IUD expulsion rate by characteristics of women, and identifies the socio demographic determinants of IUD expulsion. A Life Table method was used to calculate the cumulative expulsion rate and a random effects discrete time survival model was employed to assess the impact of potential determinants simultaneously on the risk of expelling an IUD. Results Three major findings are observed in this study. First, IUD expulsion was the second main reason, after pregnancy during IUD use, for IUD discontinuation during the first four years of IUD insertion; the expulsion rates were 6.4%, 9.1%, 10.8 %, and 12.0% at 12, 24, 36 and 48 months, respectively. Second, there was a clustering of IUD expulsion: some women experienced repeated IUD expulsions. Third, some socio demographic characteristics and fertility history were associated with the occurrence of IUD expulsion. In particular, the expulsion rate was high among young women, among those with two or more children and among those living in rural areas. Conclusion The above mentioned factors shoald be addressed in order to decrease the IUD expulsion rate and enhance the reprocluctive he alth of women.
基金supported by Independent Inovation Foundation of Shandong Univercity,IIFSDU
文摘The objective of social development is to construct a harmonious society.In China,the key to a harmonious society is the happiness of more than 900 million farmers living in the rural areas.This study aimed to measure rural residents' subjective well-being(SWB) through the day reconstruction method,as well as to analyze SWB's influencing factors through a variety of statistical methods.The results showed that the average U index was 12.79%,indicating that respondents were unhappy 12.79% of the time.Twenty-seven percent of the population had a U index greater than 0,with the average value being 47%,indicating that these people were unhappy 47% of the time.The study also found that SWB varied according to the characteristics of the respondents.Logistic regression analysis showed that social and demographic factors,including age,education,county,household size,generation number,per capita income,migration status and social networking,which significantly affected rural residents' SWB.The size of the impact varied with the different factors.
基金financial support from the National Natural Science Foundation of China(71273009)pUSDA,Economic Research Service,Cooperative Agreement(58-3000-7-0060)+2 种基金USDA,the Agricultural Food Research Initiative of the National Institute of Food and Agriculture(2010-65400-20489)USDA,Foreign Agricultural Service,th Emerging Markets Program Grant(2010-72)Chinese Universities Scientific Fund(2014RC017)
文摘Drawn on the data collected by surveying 1 340 urban households from six cities in China, this paper estimates the impacts of demographic structure and population aging on household meat consumption, by jointly considering meat consumed at home and away from home. Based on the trajectories of population, a simple simulation on meat demand trend in China is conducted subsequently. The results suggest： 1） Meat consumed away from home averagely accounts for near 30% of household total meat consumption in terms of quantity, so that its omission likely leads to a significant underestimate of total meat consumption and misunderstanding the driving forces; 2） population aging significantly and negatively affects per capita meat consumption, suggesting that the expected meat demand in China without considering population aging will be overestimated. The findings from this study have important implications for better understanding the relative issues on China＇s meat consumption under the situation of population aging.
基金supported by the National Key R&D Program of China(2020YFC2003102).
文摘Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China were selected as samples in this study using a multistage cluster random sampling method.The basic information questionnaire and Constitution in Chinese Medicine Questionnaire(Elderly Edition)were used.Descriptive statistical analysis,chi-squared tests,and binary logistic regression analysis were used.Results: The single balanced constitution(BC)accounted for 23.9%.The results of the major TCM constitution types showed that BC(43.2%)accounted for the largest proportion and unbalanced constitutions ranged from 0.9%to 15.7%.East China region(odds ratio[OR]=2.097;95%confidence interval[CI],1.912 to 2.301),married status(OR=1.341;95%CI,1.235 to 1.457),and managers(OR=1.254;95%CI,1.044 to 1.505)were significantly associated with BC.Age>70 years was associated with qi-deficiency constitution and blood stasis constitution(BSC).Female sex was significantly associated with yang-deficiency constitution(OR=1.646;95%CI,1.52 to 1.782).Southwest region was significantly associated with phlegm-dampness constitution(OR=1.809;95%CI,1.569 to 2.086).North China region was significantly associated with inherited special constitution(OR=2.521;95%CI,1.569 to 4.05).South China region(OR=2.741;95%CI,1.997 to 1.3.763),Central China region(OR=8.889;95%CI,6.676 to 11.835),senior middle school education(OR=2.442;95%CI,1.932 to 3.088),and managers(OR=1.804;95%CI,1.21 to 2.69)were significantly associated with BSC.Conclusions: This study defined the distribution characteristics and demographic factors of TCM constitution in the elderly population.Adjusting and improving unbalanced constitutions,which are correlated with diseases,can help promote healthy aging through the scientific management of these demographic factors.
基金support of the U.S.National Science Foundation (awards 8206992,8906869,9405933,9909947,0948585 to S.P.Hubbell)the John D.and Catherine D.McArthur Foundationthe Smithsonian Tropical Research Institute
文摘Background:The first three censuses of the 50-ha plot at Barro Colorado Island spanned an unusually harsh dry season during the 1983 El Nitro.By the early 1990s,we had documented increases in tree mortality,tree growth,and large population fluctuations of many species during the 1982-1985 census interval.At the time,we asserted that increasing drought frequency would greatly affect the forest.With the benefit of five more censuses at Barro Colorado from 1995-2015,we can now put the 1980 conditions in a longer perspective and test the hypothesis that increasing droughtiness has continued to change the forest.Methods:A 50-ha forest plot on Barro Colorado Island was censused eight times,in 1982 and every five years since 1985.All free-standing woody stems were measured,mapped,and identified in each census.Results:1)The period 1982-1992 included several extreme dry seasons,not just 1983,but since then there have been few such droughts.2)Dbh growth declined from a peak in the early 1980s to its lowest in the early 1990s.From 1995-2015 it increased slightly,but not returning to the initial peak.Nearly every species and all dbh categories followed the same pattern.3)The elevated stand-wide mortality rate of large trees during the 1982-1985 drought has not returned,and most individual species showed the same pattern of elevated mortality in the 1980s followed by low and fairly stable mortality after 1990.4)Sapling mortality declined after 198,5,but rose again in the late-90s,so the 1980s drought period no longer looks unusual.Mortality of individual species'saplings fluctuated erratically,including cases where mortality during the drought was lower than after.5)Population sizes of individual species fluctuated in all possible directions.Some species declined precipitously during the drought,then recovered,but others did not recover.Other species increased in abundance during the drought.Conclusions"Droughts of the 1980s elevated tree growth and mortality at Barro Colorado,but since 1990,demographic rates have remained lower,paralleling a moderate climate with few severe droughts after 1990.Moisture-demanding species suffered during the drought,but many have since recovered.We do not know how often such drought periods recur.Moreover,many species'abundances fluctuated over 35 years with no known cause.
