The purpose of this study is to correlate demography and socio-economic aspects at Irrigated Smallholder Agricultural Enterprises and their association with the Cultivation of Maize in order to determine its positive ...The purpose of this study is to correlate demography and socio-economic aspects at Irrigated Smallholder Agricultural Enterprises and their association with the Cultivation of Maize in order to determine its positive impacts at irrigated smallholders’ agricultural entrepreneurs’ household. Chi-square test was used as descriptive analysis method. The Fischer Exact tests were employed to test demography (gender, age, education, and income) in winter and summer production season of irrigated smallholder agricultural enterprises and their association with the cultivation of selected field crop (i.e. maize). The results show that gender results were not being statistically significant, as measured by the Phi measure of effect size, φ = 0.149, p = 0.011, and φ = 0.05, p = 0.392 in summer. As far as age is concern, it appears to be a statistically significant association between cultivating maize and age in winter, φ = 0.046, p = 0.730 in winter and φ = 0.172, p = 0.013. Education winter result not being statistically significant, the effect size showed a weak association, as measured by the Phi measure of effect size, φ = 0.112, p = 0.305 and φ = 0.035, p = 0.948 in summer. Income result not being statistically significant, as measured by the Phi measure of effect size, φ = 0.049, p = 0.399 and φ = 0.081, p = 0.166 in summer. In conclusion, the study shows that the development of best management practices must be based on a comprehensive analysis of the livelihoods and irrigated smallholder agricultural enterprise farming styles of participating irrigated smallholder agricultural entrepreneurs.展开更多
The attack by the Islamist group Hamas against Israel on October 7,2023,and the immediate Israeli offensive in the Gaza Strip,with the thousands of deaths and the devastation that we are witnessing daily in one of the...The attack by the Islamist group Hamas against Israel on October 7,2023,and the immediate Israeli offensive in the Gaza Strip,with the thousands of deaths and the devastation that we are witnessing daily in one of the most densely populated areas of the world,have pushed further away the prospect of a solution of coexistence between Israelis and Palestinians through the establishment of two peoples-two states,a solution that is viewed favorably in non-holy Palestinian and Israeli circles by many Western countries and by the Holy See.To complicate the socio-political picture,we recall that in the last decades,in the territories occupied by Israel in the West Bank,there has been an incessant work of human settlements and the construction of roads and infrastructures,facilitated by Israel’s rapid population growth.According to many analysts,in order to dominate the Palestinians,Israel is now implementing a real system of apartheid that is spreading from the occupied territories to the Palestinian Arab citizens of Israel.Based on the available data,which are not always reliable for political and organizational reasons of the existing statistical systems,this study attempts to grasp the strategic role that differential demography has had and continues to have in this complex conflictual reality.展开更多
We sampled twenty populations of the vulnera- ble endemic shrub or tree, Arbutus pavarii Pampan., at different elevations and aspects within the A1-Akhdar mountainous region of Libya. Our sampling sites were at elevat...We sampled twenty populations of the vulnera- ble endemic shrub or tree, Arbutus pavarii Pampan., at different elevations and aspects within the A1-Akhdar mountainous region of Libya. Our sampling sites were at elevations ranging from 285 to 738 m above sea level, and several different habitats： vallies （locally known as wadis）, north- and south-facing slopes, and mountaintops. All individuals within each quadrat were studied. Population size and structure, and plant functional traits were assessed. None of the populations had a stable distribution of size classes. Some consisted mostly of small plants, with little or no fruit production; others consisted only of mid-sized and large plants, with high fruit production, but no juvenile recruitment. There was a significant increase in percent cover with increasing elevation; reproductive output （the number of fruits per branch and total number of fruits per individual） also generally increased with elevation. In some of these populations the lack of recruitment, and in others the failure to produce fruit, together constituted serious demographic threats. In light of these results, recommen- dations are made for conservation of this vulnerable endemic species.展开更多
Habitat transformation is identified as major threat to biodiversity loss globally,affecting threatened raptors.Changes in land use can alter the abundance and distribution of birds of prey by affecting habitat availa...Habitat transformation is identified as major threat to biodiversity loss globally,affecting threatened raptors.Changes in land use can alter the abundance and distribution of birds of prey by affecting habitat availability and quality.In this study,we used multivariate analyses to investigate the effect of habitat alteration on the demography of a declining Eastern Imperial Eagle(Aqufla heliaca),making assumptions for future population trajectories.We used the Generalized Linear Mixed Models with Poisson distribution and Log link function,searching a relationship between the demographic parameters and the landscape structure and possible effects of fragmentation.In our study area,habitat change affected dramatically permanent grasslands,shrinking their availability.As we expected,the share of grasslands in eagles’territories significantly affected occupancy rate,but not productivity and breeding frequency.We found that occupancy rate decreased significantly,while productivity and breeding frequency showed no trend.Modeling the effect of habitat alteration on Eastern Imperial Eagle demography,we found out that territory quality was a more powerful factor driving the response of a top predator to the alteration of favorite foraging habitats.Only the habitat quality in source territories had a significant positive effect on eagle productivity.We found that simple rules to predict adverse agricultural impact on territory abandonment or breeding productivity of a top predator were not reliable.Our results could be used for planning conservation of other large territorial raptors,facing the same type of threat.展开更多
Background: Documenting the entire lifetime of long-lived organisms requires splicing together short-term observations. Matrix demography provides a tool to calculate lifetime statistics, but large samples from juveni...Background: Documenting the entire lifetime of long-lived organisms requires splicing together short-term observations. Matrix demography provides a tool to calculate lifetime statistics, but large samples from juvenile to adult are needed, and few such studies have been done in tropical trees because high species diversity limits sample sizes. The 50-ha plot at Barro Colorado in Panama was designed to provide large samples, and with 30years of censuses, accurate population matrices can be constructed.Methods: In 31 abundant species, I divided all individuals≥1 cm dbh into 4 or 5 size class in each of seven censuses. Movements of stems between size classes over two censuses are termed transitions, and I constructed complete transition matrices for each species. From the matrices, I derived analytic solutions for lifetime demographic statistics. Expected adult lifespan from the sapling stage was the key statistic.Results: Expected adult lifespan from the sapling stage varied 100-fold over the 31 species, from 0.5 to 50 years,and maturation time varied from 19 to nearly 200 years. Species with the highest growth rates also had high death rates, and theoretical calculations of reproductive lifespan show that the fast-growing pioneer species have short expected adult lifespans relative to the average slow-growing, shade-tolerant species. Within the slowgrowth category, however, there was high variation in expected adult lifespan, and several shade-tolerant species under-performed the pioneers in terms of adult lifespan.Conclusions: Analytical solutions from population matrices allow theoretical analyses that integrate short-term growth records into lifespans of tropical trees. The analyses suggest that pioneer species must reproduce more successfully than shade-tolerant species to persist in the Barro Colorado forest. My next goal is to incorporate seed production and germination into lifetime matrix demography to test this hypothesis.展开更多
In the context of historical Palestine, the Palestinian and Jewish demography are deeply embedded （Goldsheider, 1991; Freidlander, 2002）. The growth and structure of the populations are one of the most important too...In the context of historical Palestine, the Palestinian and Jewish demography are deeply embedded （Goldsheider, 1991; Freidlander, 2002）. The growth and structure of the populations are one of the most important tools for the control of the territory （Dahlan, 1989）. Jewish immigration was and is still considered as the single most important mean for the conquest of the land （Courbage, 2005）. Yet this is only a partial truth （Fargues, 2000）. Fertility, especially when it is natural at its peak or still very high is also a very significant asset, which is likely to reverse internal equilibrium among the different forces shaping the two societies （Courbage ＆ Todd, 2011; Ettinger, 2011）. Hence, Jews and Palestinians have embarked since decades into a demographic competition （Faraoune, personal communication, December 19, 1992; Anson ＆ Avinoam, 1996）, with this extraordinary result, that in a matter of a century （1948-2048） this small piece of land will have undergone the highest population growth on earth, equivalent to sub Saharan Africa （Faitelson, 2008; Courbage ＆ Fargues, 1997）. It is likely output is not less important to define the future nature of historical Palestine： one or two states （Baskin, 2005; Courbage, 2008）？ And if the two states solution is in effect, what kind of states would it be？ After presenting the recent trends of Palestinian demography in the context of historical Palestine since the first intifada and the aftermath of the second intifada, this essay will focus on future developments, i.e. the likely population dynamics of the Palestinian territory from 2011 until 2048, and of its different components, namely fertility. Palestinian population growth during the next four decades will be compared to that of the future Israeli population and the policy components of this differential population growth will be evaluated both in the context of historical Palestine and in the context of the Jewish State in its 1948 borders （Jews and Palestinians of 1948）. The most serious demographic challenges, （which are not those of an overall ＂equilibrium＂ between Palestinian and Jewish populations as very often claimed）, are very precisely delineated in the ground. These are, first, the question of the peopling of the settlements （Be-Tselem, 2002）. their population is likely to explode from 560,000 settlers now to 1.7 million in 2048, thanks to their extremely high fertility, low mortality, high immigration and ＂population momentum＂ （Central Bureau of Statistics, 2013; Courbage, 2006）. From 18% of the overall population of the West Bank they could reach 29% in 2048, a clear defiance to the possibility of statehood in Palestine. Besides, statehood in Palestine is also threatened by the fact that East-Jerusalem, the likely capital of the Palestinian state is also threatened by the expansionist demography of the Jewish settlers, both in the so-called ＂neighborhoods＂, those settlements close to Jerusalem but which are according to international law an integral part of the West Bank （annexed by Israel in 1967）, and inside the Old city. In Jerusalem, besides Jewish immigration to the neighborhoods from the densely and poor areas of West Jerusalem, fertility trends have now been reversed to advantage of the Jews as compared to the Palestinians in the Holy city （Della Pergola, 2001）. This presentation will deal also with the population trends of the Palestinian population from now on until 2048 （Dalen ＆ Petersen, 2004; Courbage, 1999）. Under the impact of a higher fertility, and a population momentum clearly to its benefit, the population of Gaza （all Palestinians） could approach the Palestinian population of the West Bank： 4.0 in Gaza, 4.3 in the WB （Clarens, 2011）. Yet, the slight majority in the West Bank comes from the Palestinians in Jerusalem, whose political status is still vague. A larger share of the Palestinian population living in the Gaza strip rather than in the West bank is probably not devoid of political implications. For the policy makers it is not easy to run against demographic trends, especially when they are largely guided and decided by the other State which shares the same land. Yet, it is of utmost importance to be fully aware of the likely evolution of the demographic landscape in Palestine and to prepare the demographic but mostly non-demographic policy measures to counterbalance their effects.展开更多
Demography plays a fundamental role in shaping the landscape of human resources.The interdependent relationship between these two fields is observable in the workforce composition,labor market trends,talent management...Demography plays a fundamental role in shaping the landscape of human resources.The interdependent relationship between these two fields is observable in the workforce composition,labor market trends,talent management strategies and on learning.Changes perceived in demographic changes are shaping and transforming human resources management.In an era marked by demographic shifts,technological advancements,and evolving work preferences,organizations are facing the need to understand and adapt to the changing demographics to effectively manage their human resources.This article explores how demography influences human resource(HR)with a special highlight on the management of multigenerational workforce.展开更多
Temperate rainforests have historically been considered highly vulnerable to disturbance.Climate change,which is expected to increase the intensity,frequency,and impacts of disturbance events,is consequently a signifi...Temperate rainforests have historically been considered highly vulnerable to disturbance.Climate change,which is expected to increase the intensity,frequency,and impacts of disturbance events,is consequently a significant threat to their long-term persistence.However,data describing the long-term response of temperate rainforests to disturbance is rare.In the cool temperate rainforests of northern New South Wales,Australia,Nothofagus moorei is considered especially vulnerable to climate change due to a decreasing number of mature individuals,limited remaining suitable habitat,and low rates of sexual regeneration.In this study,we used over 50 years of empirical data from silvicultural experiments with multiple thinning intensities to characterise the demographic responses(i.e.,growth,mortality,and recruitment)of cool temperate rainforest species,including N.moorei,to disturbance over time.Cool temperate rainforest species showed resilience to disturbance,predominantly through their widespread ability to basally coppice.Nothofagus moorei,in particular,demonstrated higher rates of successful sexual and vegetative recruitment and grew faster in response to higher intensities of disturbance,in comparison to very low rates of recruitment pre-disturbance.These results challenge successional models that position rainforests as disturbance-sensitive ecosystems and identify N.moorei as a species that requires large-scale disturbance to successfully regenerate.Management regimes that actively exclude disturbance from these forests risk the local loss of disturbance-dependent rainforest species such as N.moorei.展开更多
Background The full lifespan of long-lived trees includes a seedling phase,during which a seed germinates and grows to a size large enough to be measured in forest inventories.Seedling populations are usually studied ...Background The full lifespan of long-lived trees includes a seedling phase,during which a seed germinates and grows to a size large enough to be measured in forest inventories.Seedling populations are usually studied separately from adult trees,and the seedling lifespan,from seed to sapling,is poorly known.In the 50-ha Barro Colorado forest plot,we started intensive censuses of seeds and seedlings in 1994 in order to merge seedling and adult demography and document complete lifespans.Methods In 17 species abundant in seedling censuses,we subdivided populations into six size classes from seed to 1cm dbh,including seeds plus five seedling stages.The smallest seedling class was subdivided by age.Censuses in two consecutive years provided transition matrices describing the probability that a seedling in one stage moved to another one year later.For each species,we averaged the transition matrix across 25 censuses and used it to project the seedling lifespan,from seed until 1cm dbh or death.Results The predicted mean survival rate of seeds to 1cm dbh varied 1000-fold across species,from 2.9×10^(−6)to 4.4×10^(−3);the median was 2.0×10^(−4).The seedling lifespan,or the average time it takes a seed to grow to 1cm dbh,varied across species from 5.1 to 53.1 years,with a median of 20.3 years.In the median species,the 10%fastest-growing seeds would reach 1cm dbh in 9.0 years,and the slowest 10%in 34.6 years.Conclusions Combining seedling results with our previous study of lifespan after 1cm dbh,we estimate that the focal species have full lifespans varying from 41 years in a gap-demanding pioneer to 320 years in one shade-tolerant species.Lifetime demography can contribute precise survival rates and lifespans to forestry models.展开更多
Studies on the effect of temperature on the development of the water chestnut beetle, Galerucella birmanica Jacoby were carried out in the laboratory at seven different temperatures： 16 ℃, 19 ℃, 22 ℃, 25 ℃, 28 ℃...Studies on the effect of temperature on the development of the water chestnut beetle, Galerucella birmanica Jacoby were carried out in the laboratory at seven different temperatures： 16 ℃, 19 ℃, 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃. The developmental time decreased with increase in temperature. The developmental time at 16 ℃, 19℃, 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃ was 96.60, 80.68, 58.96, 43.48, 35.03, 30.08 and 28.02 days for the period from egg hatching to adult emergence, respectively. The developmental threshold estimated for a generation by linear regression was 10.36℃. The fecundity per female at 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃ was 102.3, 134.5, 141.2, 130.1 and 116.2 eggs, respectively. Oviposition period ranged from 15.6 days at 22 ℃ to 8.6 days at 34 ℃. Hatchability of eggs was highest at 31 ℃ with 76.9% and lowest at 34 ℃ with 57.1%. The highest generation survival rate was 65.3% at 31 ℃, and the intrinsic rate of natural increase （rm） for G. birmanica was the highest at 34 ℃.展开更多
Reproduction and population parameters of vegetable leafminer, Liriomyza sativae Blanchard were measured on cucumber （Cucumis sativus L.） at seven constant temperatures （10, 15, 20, 25, 30, 35 and 40℃）. No eggs w...Reproduction and population parameters of vegetable leafminer, Liriomyza sativae Blanchard were measured on cucumber （Cucumis sativus L.） at seven constant temperatures （10, 15, 20, 25, 30, 35 and 40℃）. No eggs were found at 10℃ and flies died after exposure to 40℃. The significantly highest intrinsic rate of natural increase （rm）, net reproductive rate （R0） and finite rate of increase （λ） ofL. sativae were obtained at 25℃ as 0.196, 52.452, and 1.216, respectively. The above-mentioned parameters decreased at 15℃ and 135℃ and this reduction at 35℃ was strong. Doubling time （DT） varied significantly with temperature. The shortest doubling time was obtained at 25℃. Mean generation time （T） decreased significantly with increasing temperature between 15℃ and 35℃. Percentage of immature ages in the stable age distribution was more than 95% at all temperatures. Female longevity was greater than male at all temperatures. Liriomyza sativae lived for a long time at 15℃, whereas at 35℃ had lower survival rates. The effect of temperature on reproduction, especially the intrinsic rate of increase of L. sativae would be useful for predicting its longterm population fluctuation over several generations.展开更多
In this paper we build the multi-state evolution equation of family population to describe the women’s marital statuses, fertility statuses, parity statuses, the number of surviving children statuses, family marker s...In this paper we build the multi-state evolution equation of family population to describe the women’s marital statuses, fertility statuses, parity statuses, the number of surviving children statuses, family marker statuses, etc. and the women statuses dynamic transition between different statuses is computed from age-specific transition probabilities. Also we build some family demography indexes.This work is supported by the Management Decision & Information System Research Laboratory.展开更多
Although entrepreneurial orientation has been identified as a key facilitator of a firm＇s innovative behaviors, its antecedents, especially the determinant role of the business leader, have yet to be explored. Drawin...Although entrepreneurial orientation has been identified as a key facilitator of a firm＇s innovative behaviors, its antecedents, especially the determinant role of the business leader, have yet to be explored. Drawing on strategic leadership theory, which posits the role of CEO in determining a firm＇s strategic direction, we examined the influence of CEO demography, specifically age, tenure, and education, on a firm＇s entrepreneurial orientation. Based on a sample of 231 Chinese firms, we found firms with a CEO who was younger, higher educated, and with a shorter tenure on the job had a greater extent of entrepreneurial orientation. Moreover, the firm＇s competitive environment moderated these relationships.展开更多
The main goal of this research is to assess the impact of race, age at diagnosis, sex, and phenotype on the incidence and survivability of acute lymphocytic leukemia (ALL) among patients in the United States. By takin...The main goal of this research is to assess the impact of race, age at diagnosis, sex, and phenotype on the incidence and survivability of acute lymphocytic leukemia (ALL) among patients in the United States. By taking these factors into account, the study aims to explore how existing cancer registry data can aid in the early detection and effective treatment of ALL in patients. Our hypothesis was that statistically significant correlations exist between race, age at which patients were diagnosed, sex, and phenotype of the ALL patients, and their rate of incidence and survivability data were evaluated using SEER*Stat statistical software from National Cancer Institute. Analysis of the incidence data revealed that a higher prevalence of ALL was among the Caucasian population. The majority of ALL cases (59%) occurred in patients aged between 0 to 19 years at the time of diagnosis, and 56% of the affected individuals were male. The B-cell phenotype was predominantly associated with ALL cases (73%). When analyzing survivability data, it was observed that the 5-year survival rates slightly exceeded the 10-year survival rates for the respective demographics. Survivability rates of African Americans patients were the lowest compared to Caucasian, Asian, Pacific Islanders, Alaskan Native, Native Americans and others. Survivability rates progressively decreased for older patients. Moreover, this study investigated the typical treatment methods applied to ALL patients, mainly comprising chemotherapy, with occasional supplementation of radiation therapy as required. The study demonstrated the considerable efficacy of chemotherapy in enhancing patients’ chances of survival, while those who remained untreated faced a less favorable prognosis from the disease. Although a significant amount of data and information exists, this study can help doctors in the future by diagnosing patients with certain characteristics. It will further assist the health care professionals in screening potential patients and early detection of cases. This could also save the lives of elderly patients who have a higher mortality rate from this disease.展开更多
Celiac disease(CD) is one of the most common diseases,resulting from both environmental(gluten) and genetic factors [human leukocyte antigen(HLA) and nonHLA genes].The prevalence of CD has been estimated to approximat...Celiac disease(CD) is one of the most common diseases,resulting from both environmental(gluten) and genetic factors [human leukocyte antigen(HLA) and nonHLA genes].The prevalence of CD has been estimated to approximate 0.5%-1% in different parts of the world.However,the population with diabetes,autoimmune disorder or relatives of CD individuals have even higher risk for the development of CD,at least in part,because of shared HLA typing.Gliadin gains access to the basal surface of the epithelium,and interact directly with the immune system,via both trans-and para-cellular routes.From a diagnostic perspective,symptoms may be viewed as either "typical" or "atypical".In both positive serological screening results suggestive of CD,should lead to small bowel biopsy followed by a favourable clinical and serological response to the gluten-free diet(GFD) to confirm the diagnosis.Positive anti-tissue transglutaminase antibody or antiendomysial antibody during the clinical course helps to confirm the diagnosis of CD because of their over 99% specificities when small bowel villous atrophy is present on biopsy.Currently,the only treatment available for CD individuals is a strict life-long GFD.A greater understanding of the pathogenesis of CD allows alternative future CD treatments to hydrolyse toxic gliadin peptide,prevent toxic gliadin peptide absorption,blockage of selective deamidation of specific glutamine residues by tissue,restore immune tolerance towards gluten,modulation of immune response to dietary gliadin,and restoration of intestinal architecture.展开更多
This study compared the diagnostic efficacy of transrectal ultrasound(TRUS)-guided prostate biopsy(TRBx)and transperineal prostate biopsy(TPBx)in patients with suspected prostate cancer(PCa).We enrolled 2962 men who u...This study compared the diagnostic efficacy of transrectal ultrasound(TRUS)-guided prostate biopsy(TRBx)and transperineal prostate biopsy(TPBx)in patients with suspected prostate cancer(PCa).We enrolled 2962 men who underwent transrectal(n=1216)or transperineal(n=1746)systematic 12-core prostate biopsy.Clinical data including age,prostate-specific antigen(PSA)level,and prostate volume(PV)were recorded.To minimize confounding,we performed propensity score-matching analysis?We measured and compared PCa detection rates between TRBx and TPBx,which were stratified by clinical characteristics and Gleason scores.The effects of clinical characteristics on PCa detection rate were assessed by logistic regression.For all patients,TPBx detected a higher proportion of clinically significant PCa(P<0.001).Logistic regression analyses illustrated that PV had a smaller impact on PCa detection rate of TPBx compared with TRBx.Propensity score-matching analysis showed that the detection rates in TRBx were higher than those in TPBx for patients aged≥80 years(80.4%vs 56.5%,P=0.004)and with PSA level 20.1-100.0 ng ml^-1(80.8%vs 69.1%,P=0.040).In conclusion,TPBx was associated with a higher detection rate of clinically significant PCa than TRBx was;however,because of the high detection rate at certain ages and PSA levels,biopsy approaches should be optimized according to patents'clinical characteristics.展开更多
Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations.In this study,we used double digest restriction-siteassociated DNA...Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations.In this study,we used double digest restriction-siteassociated DNA sequencing(ddRAD)technology to assess the genetic diversity,genetic structure and demographic history of the three extant populations of R.meddianum.Analysis of SNPs indicated that R.meddianum populations have a high genetic diversity(p?0.0772±0.0024,HE?0.0742±0.002).Both FST values(0.1582e0.2388)and AMOVA showed a moderate genetic differentiation among the R.meddianum populations.Meanwhile,STRUCTURE,PCoA and NJ trees indicated that the R.meddianum samples were clustered into three distinct genetic groups.Using the stairway plot,we found that R.meddianum underwent a population bottleneck about 70,000 years ago.Furthermore,demographic models of R.meddianum and its relative,Rhododendron cyanocarpum,revealed that these species diverged about 3.05(2.21e5.03)million years ago.This divergence may have been caused by environmental changes that occurred after the late Pliocene,e.g.,the Asian winter monsoon intensified,leading to a drier climate.Based on these findings,we recommend that R.meddianum be conserved through in situ,ex situ approaches and that its seeds be collected for germplasm.展开更多
Background: Tree demography is an essential indicator of various forest ecosystem services, and understanding its changes is critical for the sustainable management of forests. During the past four decades, China impl...Background: Tree demography is an essential indicator of various forest ecosystem services, and understanding its changes is critical for the sustainable management of forests. During the past four decades, China implemented unprecedented forest restoration projects, which altered tree demography by increasing the number of trees and introducing new species. However, it remains unclear how species composition has changed in China in response to the past forest restoration and demographical processes.Methods: We applied Forest Stability Index(FSI) and the relative change of FSI(%FSI) to describe the population dynamics of tree species and structure in China since 1998, using field-survey data collected from over 200,000plot-records from the 6th to 9th National Forest Inventories(NFIs).Results: The overall populations of both natural and planted forests have grown rapidly from 1998 to 2018, while the range of changes in the relative tree density was more variable for natural forests(ranging from-8.53% to42.46%) than for planted forests(ranging from-1.01% to 13.31%). The populations declined only in some of the tree species, including Betula platyphylla, Ulmus pumila, and Robinia pseudoacacia. In contrast, the populations of trees in the largest size-class either remained stable or expanded.Conclusions: Tree density of China?s forests(both natural and planted forests) generally expanded and the overall populations increased in most size classes, with greater increases occurred in planted forests. In contrasting to the global decline trends of large diameter trees, here we found no apparent decline for trees in the largest size-class in China, highlighting China?s success in improving forest health and forest adaptations to climate change. We advocate for more studies to reveal the mechanisms of the changes in tree demography, which will help to improve forest ecosystem services such as the carbon sequestration capacity.展开更多
Recent advances in high-throughput sequencing technologies have revolutionized the field of population genetics. Data now routinely contain genomic level polymorphism information, and the low cost of DNA sequencing en...Recent advances in high-throughput sequencing technologies have revolutionized the field of population genetics. Data now routinely contain genomic level polymorphism information, and the low cost of DNA sequencing enables researchers to investigate tens of thousands of subjects at a time. This provides an unprecedented opportunity to address fundamental evolutionary questions, while posing challenges on traditional population genetic theories and methods. This review provides an overview of the recent methodological developments in the field of population genetics, specifically methods used to infer ancient population history and investigate natural selection using large-sample, large-scale genetic data. Several open questions are also discussed at the end of the review.展开更多
文摘The purpose of this study is to correlate demography and socio-economic aspects at Irrigated Smallholder Agricultural Enterprises and their association with the Cultivation of Maize in order to determine its positive impacts at irrigated smallholders’ agricultural entrepreneurs’ household. Chi-square test was used as descriptive analysis method. The Fischer Exact tests were employed to test demography (gender, age, education, and income) in winter and summer production season of irrigated smallholder agricultural enterprises and their association with the cultivation of selected field crop (i.e. maize). The results show that gender results were not being statistically significant, as measured by the Phi measure of effect size, φ = 0.149, p = 0.011, and φ = 0.05, p = 0.392 in summer. As far as age is concern, it appears to be a statistically significant association between cultivating maize and age in winter, φ = 0.046, p = 0.730 in winter and φ = 0.172, p = 0.013. Education winter result not being statistically significant, the effect size showed a weak association, as measured by the Phi measure of effect size, φ = 0.112, p = 0.305 and φ = 0.035, p = 0.948 in summer. Income result not being statistically significant, as measured by the Phi measure of effect size, φ = 0.049, p = 0.399 and φ = 0.081, p = 0.166 in summer. In conclusion, the study shows that the development of best management practices must be based on a comprehensive analysis of the livelihoods and irrigated smallholder agricultural enterprise farming styles of participating irrigated smallholder agricultural entrepreneurs.
文摘The attack by the Islamist group Hamas against Israel on October 7,2023,and the immediate Israeli offensive in the Gaza Strip,with the thousands of deaths and the devastation that we are witnessing daily in one of the most densely populated areas of the world,have pushed further away the prospect of a solution of coexistence between Israelis and Palestinians through the establishment of two peoples-two states,a solution that is viewed favorably in non-holy Palestinian and Israeli circles by many Western countries and by the Holy See.To complicate the socio-political picture,we recall that in the last decades,in the territories occupied by Israel in the West Bank,there has been an incessant work of human settlements and the construction of roads and infrastructures,facilitated by Israel’s rapid population growth.According to many analysts,in order to dominate the Palestinians,Israel is now implementing a real system of apartheid that is spreading from the occupied territories to the Palestinian Arab citizens of Israel.Based on the available data,which are not always reliable for political and organizational reasons of the existing statistical systems,this study attempts to grasp the strategic role that differential demography has had and continues to have in this complex conflictual reality.
文摘We sampled twenty populations of the vulnera- ble endemic shrub or tree, Arbutus pavarii Pampan., at different elevations and aspects within the A1-Akhdar mountainous region of Libya. Our sampling sites were at elevations ranging from 285 to 738 m above sea level, and several different habitats： vallies （locally known as wadis）, north- and south-facing slopes, and mountaintops. All individuals within each quadrat were studied. Population size and structure, and plant functional traits were assessed. None of the populations had a stable distribution of size classes. Some consisted mostly of small plants, with little or no fruit production; others consisted only of mid-sized and large plants, with high fruit production, but no juvenile recruitment. There was a significant increase in percent cover with increasing elevation; reproductive output （the number of fruits per branch and total number of fruits per individual） also generally increased with elevation. In some of these populations the lack of recruitment, and in others the failure to produce fruit, together constituted serious demographic threats. In light of these results, recommen- dations are made for conservation of this vulnerable endemic species.
基金funded by the LIFE Program of the European Union under the project’Restoration and sustainable management of Imperial Eagle’s foraging habitats in key Natura 2000 sites in Bulgaria’LIFE14 NAT/BG/001119。
文摘Habitat transformation is identified as major threat to biodiversity loss globally,affecting threatened raptors.Changes in land use can alter the abundance and distribution of birds of prey by affecting habitat availability and quality.In this study,we used multivariate analyses to investigate the effect of habitat alteration on the demography of a declining Eastern Imperial Eagle(Aqufla heliaca),making assumptions for future population trajectories.We used the Generalized Linear Mixed Models with Poisson distribution and Log link function,searching a relationship between the demographic parameters and the landscape structure and possible effects of fragmentation.In our study area,habitat change affected dramatically permanent grasslands,shrinking their availability.As we expected,the share of grasslands in eagles’territories significantly affected occupancy rate,but not productivity and breeding frequency.We found that occupancy rate decreased significantly,while productivity and breeding frequency showed no trend.Modeling the effect of habitat alteration on Eastern Imperial Eagle demography,we found out that territory quality was a more powerful factor driving the response of a top predator to the alteration of favorite foraging habitats.Only the habitat quality in source territories had a significant positive effect on eagle productivity.We found that simple rules to predict adverse agricultural impact on territory abandonment or breeding productivity of a top predator were not reliable.Our results could be used for planning conservation of other large territorial raptors,facing the same type of threat.
基金Numerous grants from National Science Foundation (US), the Smithsonian Institution, the Mac Arthur Foundation, and Earthwatch supported census work in the Barro Colorado 50-ha plotThe Center for Forest Science at the Morton Arboretum provided support for the author while writing
文摘Background: Documenting the entire lifetime of long-lived organisms requires splicing together short-term observations. Matrix demography provides a tool to calculate lifetime statistics, but large samples from juvenile to adult are needed, and few such studies have been done in tropical trees because high species diversity limits sample sizes. The 50-ha plot at Barro Colorado in Panama was designed to provide large samples, and with 30years of censuses, accurate population matrices can be constructed.Methods: In 31 abundant species, I divided all individuals≥1 cm dbh into 4 or 5 size class in each of seven censuses. Movements of stems between size classes over two censuses are termed transitions, and I constructed complete transition matrices for each species. From the matrices, I derived analytic solutions for lifetime demographic statistics. Expected adult lifespan from the sapling stage was the key statistic.Results: Expected adult lifespan from the sapling stage varied 100-fold over the 31 species, from 0.5 to 50 years,and maturation time varied from 19 to nearly 200 years. Species with the highest growth rates also had high death rates, and theoretical calculations of reproductive lifespan show that the fast-growing pioneer species have short expected adult lifespans relative to the average slow-growing, shade-tolerant species. Within the slowgrowth category, however, there was high variation in expected adult lifespan, and several shade-tolerant species under-performed the pioneers in terms of adult lifespan.Conclusions: Analytical solutions from population matrices allow theoretical analyses that integrate short-term growth records into lifespans of tropical trees. The analyses suggest that pioneer species must reproduce more successfully than shade-tolerant species to persist in the Barro Colorado forest. My next goal is to incorporate seed production and germination into lifetime matrix demography to test this hypothesis.
文摘In the context of historical Palestine, the Palestinian and Jewish demography are deeply embedded （Goldsheider, 1991; Freidlander, 2002）. The growth and structure of the populations are one of the most important tools for the control of the territory （Dahlan, 1989）. Jewish immigration was and is still considered as the single most important mean for the conquest of the land （Courbage, 2005）. Yet this is only a partial truth （Fargues, 2000）. Fertility, especially when it is natural at its peak or still very high is also a very significant asset, which is likely to reverse internal equilibrium among the different forces shaping the two societies （Courbage ＆ Todd, 2011; Ettinger, 2011）. Hence, Jews and Palestinians have embarked since decades into a demographic competition （Faraoune, personal communication, December 19, 1992; Anson ＆ Avinoam, 1996）, with this extraordinary result, that in a matter of a century （1948-2048） this small piece of land will have undergone the highest population growth on earth, equivalent to sub Saharan Africa （Faitelson, 2008; Courbage ＆ Fargues, 1997）. It is likely output is not less important to define the future nature of historical Palestine： one or two states （Baskin, 2005; Courbage, 2008）？ And if the two states solution is in effect, what kind of states would it be？ After presenting the recent trends of Palestinian demography in the context of historical Palestine since the first intifada and the aftermath of the second intifada, this essay will focus on future developments, i.e. the likely population dynamics of the Palestinian territory from 2011 until 2048, and of its different components, namely fertility. Palestinian population growth during the next four decades will be compared to that of the future Israeli population and the policy components of this differential population growth will be evaluated both in the context of historical Palestine and in the context of the Jewish State in its 1948 borders （Jews and Palestinians of 1948）. The most serious demographic challenges, （which are not those of an overall ＂equilibrium＂ between Palestinian and Jewish populations as very often claimed）, are very precisely delineated in the ground. These are, first, the question of the peopling of the settlements （Be-Tselem, 2002）. their population is likely to explode from 560,000 settlers now to 1.7 million in 2048, thanks to their extremely high fertility, low mortality, high immigration and ＂population momentum＂ （Central Bureau of Statistics, 2013; Courbage, 2006）. From 18% of the overall population of the West Bank they could reach 29% in 2048, a clear defiance to the possibility of statehood in Palestine. Besides, statehood in Palestine is also threatened by the fact that East-Jerusalem, the likely capital of the Palestinian state is also threatened by the expansionist demography of the Jewish settlers, both in the so-called ＂neighborhoods＂, those settlements close to Jerusalem but which are according to international law an integral part of the West Bank （annexed by Israel in 1967）, and inside the Old city. In Jerusalem, besides Jewish immigration to the neighborhoods from the densely and poor areas of West Jerusalem, fertility trends have now been reversed to advantage of the Jews as compared to the Palestinians in the Holy city （Della Pergola, 2001）. This presentation will deal also with the population trends of the Palestinian population from now on until 2048 （Dalen ＆ Petersen, 2004; Courbage, 1999）. Under the impact of a higher fertility, and a population momentum clearly to its benefit, the population of Gaza （all Palestinians） could approach the Palestinian population of the West Bank： 4.0 in Gaza, 4.3 in the WB （Clarens, 2011）. Yet, the slight majority in the West Bank comes from the Palestinians in Jerusalem, whose political status is still vague. A larger share of the Palestinian population living in the Gaza strip rather than in the West bank is probably not devoid of political implications. For the policy makers it is not easy to run against demographic trends, especially when they are largely guided and decided by the other State which shares the same land. Yet, it is of utmost importance to be fully aware of the likely evolution of the demographic landscape in Palestine and to prepare the demographic but mostly non-demographic policy measures to counterbalance their effects.
文摘Demography plays a fundamental role in shaping the landscape of human resources.The interdependent relationship between these two fields is observable in the workforce composition,labor market trends,talent management strategies and on learning.Changes perceived in demographic changes are shaping and transforming human resources management.In an era marked by demographic shifts,technological advancements,and evolving work preferences,organizations are facing the need to understand and adapt to the changing demographics to effectively manage their human resources.This article explores how demography influences human resource(HR)with a special highlight on the management of multigenerational workforce.
基金supported by the Bushfire and Natural Hazards Cooperative Research Centre and New South Wales National Parks and Wildlife Service.
文摘Temperate rainforests have historically been considered highly vulnerable to disturbance.Climate change,which is expected to increase the intensity,frequency,and impacts of disturbance events,is consequently a significant threat to their long-term persistence.However,data describing the long-term response of temperate rainforests to disturbance is rare.In the cool temperate rainforests of northern New South Wales,Australia,Nothofagus moorei is considered especially vulnerable to climate change due to a decreasing number of mature individuals,limited remaining suitable habitat,and low rates of sexual regeneration.In this study,we used over 50 years of empirical data from silvicultural experiments with multiple thinning intensities to characterise the demographic responses(i.e.,growth,mortality,and recruitment)of cool temperate rainforest species,including N.moorei,to disturbance over time.Cool temperate rainforest species showed resilience to disturbance,predominantly through their widespread ability to basally coppice.Nothofagus moorei,in particular,demonstrated higher rates of successful sexual and vegetative recruitment and grew faster in response to higher intensities of disturbance,in comparison to very low rates of recruitment pre-disturbance.These results challenge successional models that position rainforests as disturbance-sensitive ecosystems and identify N.moorei as a species that requires large-scale disturbance to successfully regenerate.Management regimes that actively exclude disturbance from these forests risk the local loss of disturbance-dependent rainforest species such as N.moorei.
基金funded by the Environmental Seed Arrival and Interspecific Associations in Seedling Sciences Program of the Smithsonian Institutionthe National Science Foundation (DEB-0075102,DEB-0823728,DEB-0640386,DEB-1242622,DEB-1464389)the Andrew Mellon Foundation,The Ohio State University,and Yale University
文摘Background The full lifespan of long-lived trees includes a seedling phase,during which a seed germinates and grows to a size large enough to be measured in forest inventories.Seedling populations are usually studied separately from adult trees,and the seedling lifespan,from seed to sapling,is poorly known.In the 50-ha Barro Colorado forest plot,we started intensive censuses of seeds and seedlings in 1994 in order to merge seedling and adult demography and document complete lifespans.Methods In 17 species abundant in seedling censuses,we subdivided populations into six size classes from seed to 1cm dbh,including seeds plus five seedling stages.The smallest seedling class was subdivided by age.Censuses in two consecutive years provided transition matrices describing the probability that a seedling in one stage moved to another one year later.For each species,we averaged the transition matrix across 25 censuses and used it to project the seedling lifespan,from seed until 1cm dbh or death.Results The predicted mean survival rate of seeds to 1cm dbh varied 1000-fold across species,from 2.9×10^(−6)to 4.4×10^(−3);the median was 2.0×10^(−4).The seedling lifespan,or the average time it takes a seed to grow to 1cm dbh,varied across species from 5.1 to 53.1 years,with a median of 20.3 years.In the median species,the 10%fastest-growing seeds would reach 1cm dbh in 9.0 years,and the slowest 10%in 34.6 years.Conclusions Combining seedling results with our previous study of lifespan after 1cm dbh,we estimate that the focal species have full lifespans varying from 41 years in a gap-demanding pioneer to 320 years in one shade-tolerant species.Lifetime demography can contribute precise survival rates and lifespans to forestry models.
文摘Studies on the effect of temperature on the development of the water chestnut beetle, Galerucella birmanica Jacoby were carried out in the laboratory at seven different temperatures： 16 ℃, 19 ℃, 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃. The developmental time decreased with increase in temperature. The developmental time at 16 ℃, 19℃, 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃ was 96.60, 80.68, 58.96, 43.48, 35.03, 30.08 and 28.02 days for the period from egg hatching to adult emergence, respectively. The developmental threshold estimated for a generation by linear regression was 10.36℃. The fecundity per female at 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃ was 102.3, 134.5, 141.2, 130.1 and 116.2 eggs, respectively. Oviposition period ranged from 15.6 days at 22 ℃ to 8.6 days at 34 ℃. Hatchability of eggs was highest at 31 ℃ with 76.9% and lowest at 34 ℃ with 57.1%. The highest generation survival rate was 65.3% at 31 ℃, and the intrinsic rate of natural increase （rm） for G. birmanica was the highest at 34 ℃.
文摘Reproduction and population parameters of vegetable leafminer, Liriomyza sativae Blanchard were measured on cucumber （Cucumis sativus L.） at seven constant temperatures （10, 15, 20, 25, 30, 35 and 40℃）. No eggs were found at 10℃ and flies died after exposure to 40℃. The significantly highest intrinsic rate of natural increase （rm）, net reproductive rate （R0） and finite rate of increase （λ） ofL. sativae were obtained at 25℃ as 0.196, 52.452, and 1.216, respectively. The above-mentioned parameters decreased at 15℃ and 135℃ and this reduction at 35℃ was strong. Doubling time （DT） varied significantly with temperature. The shortest doubling time was obtained at 25℃. Mean generation time （T） decreased significantly with increasing temperature between 15℃ and 35℃. Percentage of immature ages in the stable age distribution was more than 95% at all temperatures. Female longevity was greater than male at all temperatures. Liriomyza sativae lived for a long time at 15℃, whereas at 35℃ had lower survival rates. The effect of temperature on reproduction, especially the intrinsic rate of increase of L. sativae would be useful for predicting its longterm population fluctuation over several generations.
文摘In this paper we build the multi-state evolution equation of family population to describe the women’s marital statuses, fertility statuses, parity statuses, the number of surviving children statuses, family marker statuses, etc. and the women statuses dynamic transition between different statuses is computed from age-specific transition probabilities. Also we build some family demography indexes.This work is supported by the Management Decision & Information System Research Laboratory.
基金Acknowledgements We appreciate the financial support from the Faculty Research Grant of Hong Kong Baptist University （FRG2/10-11/064）. The study is also supported by two research grants from the National Natural Science Foundation of China （No. 70902050 and No. 71272186）, two research grants from the Chinese Ministry of Education of China （No. 09YJC630132 and No. 201190）.
文摘Although entrepreneurial orientation has been identified as a key facilitator of a firm＇s innovative behaviors, its antecedents, especially the determinant role of the business leader, have yet to be explored. Drawing on strategic leadership theory, which posits the role of CEO in determining a firm＇s strategic direction, we examined the influence of CEO demography, specifically age, tenure, and education, on a firm＇s entrepreneurial orientation. Based on a sample of 231 Chinese firms, we found firms with a CEO who was younger, higher educated, and with a shorter tenure on the job had a greater extent of entrepreneurial orientation. Moreover, the firm＇s competitive environment moderated these relationships.
文摘The main goal of this research is to assess the impact of race, age at diagnosis, sex, and phenotype on the incidence and survivability of acute lymphocytic leukemia (ALL) among patients in the United States. By taking these factors into account, the study aims to explore how existing cancer registry data can aid in the early detection and effective treatment of ALL in patients. Our hypothesis was that statistically significant correlations exist between race, age at which patients were diagnosed, sex, and phenotype of the ALL patients, and their rate of incidence and survivability data were evaluated using SEER*Stat statistical software from National Cancer Institute. Analysis of the incidence data revealed that a higher prevalence of ALL was among the Caucasian population. The majority of ALL cases (59%) occurred in patients aged between 0 to 19 years at the time of diagnosis, and 56% of the affected individuals were male. The B-cell phenotype was predominantly associated with ALL cases (73%). When analyzing survivability data, it was observed that the 5-year survival rates slightly exceeded the 10-year survival rates for the respective demographics. Survivability rates of African Americans patients were the lowest compared to Caucasian, Asian, Pacific Islanders, Alaskan Native, Native Americans and others. Survivability rates progressively decreased for older patients. Moreover, this study investigated the typical treatment methods applied to ALL patients, mainly comprising chemotherapy, with occasional supplementation of radiation therapy as required. The study demonstrated the considerable efficacy of chemotherapy in enhancing patients’ chances of survival, while those who remained untreated faced a less favorable prognosis from the disease. Although a significant amount of data and information exists, this study can help doctors in the future by diagnosing patients with certain characteristics. It will further assist the health care professionals in screening potential patients and early detection of cases. This could also save the lives of elderly patients who have a higher mortality rate from this disease.
文摘Celiac disease(CD) is one of the most common diseases,resulting from both environmental(gluten) and genetic factors [human leukocyte antigen(HLA) and nonHLA genes].The prevalence of CD has been estimated to approximate 0.5%-1% in different parts of the world.However,the population with diabetes,autoimmune disorder or relatives of CD individuals have even higher risk for the development of CD,at least in part,because of shared HLA typing.Gliadin gains access to the basal surface of the epithelium,and interact directly with the immune system,via both trans-and para-cellular routes.From a diagnostic perspective,symptoms may be viewed as either "typical" or "atypical".In both positive serological screening results suggestive of CD,should lead to small bowel biopsy followed by a favourable clinical and serological response to the gluten-free diet(GFD) to confirm the diagnosis.Positive anti-tissue transglutaminase antibody or antiendomysial antibody during the clinical course helps to confirm the diagnosis of CD because of their over 99% specificities when small bowel villous atrophy is present on biopsy.Currently,the only treatment available for CD individuals is a strict life-long GFD.A greater understanding of the pathogenesis of CD allows alternative future CD treatments to hydrolyse toxic gliadin peptide,prevent toxic gliadin peptide absorption,blockage of selective deamidation of specific glutamine residues by tissue,restore immune tolerance towards gluten,modulation of immune response to dietary gliadin,and restoration of intestinal architecture.
基金This study was supported by the National Natural Science Foundation of China(No.81570682,No.81772746,and No.81870516)the grants from Shanghai Municipal Health Bureau(No.2013ZYJB0102).
文摘This study compared the diagnostic efficacy of transrectal ultrasound(TRUS)-guided prostate biopsy(TRBx)and transperineal prostate biopsy(TPBx)in patients with suspected prostate cancer(PCa).We enrolled 2962 men who underwent transrectal(n=1216)or transperineal(n=1746)systematic 12-core prostate biopsy.Clinical data including age,prostate-specific antigen(PSA)level,and prostate volume(PV)were recorded.To minimize confounding,we performed propensity score-matching analysis?We measured and compared PCa detection rates between TRBx and TPBx,which were stratified by clinical characteristics and Gleason scores.The effects of clinical characteristics on PCa detection rate were assessed by logistic regression.For all patients,TPBx detected a higher proportion of clinically significant PCa(P<0.001).Logistic regression analyses illustrated that PV had a smaller impact on PCa detection rate of TPBx compared with TRBx.Propensity score-matching analysis showed that the detection rates in TRBx were higher than those in TPBx for patients aged≥80 years(80.4%vs 56.5%,P=0.004)and with PSA level 20.1-100.0 ng ml^-1(80.8%vs 69.1%,P=0.040).In conclusion,TPBx was associated with a higher detection rate of clinically significant PCa than TRBx was;however,because of the high detection rate at certain ages and PSA levels,biopsy approaches should be optimized according to patents'clinical characteristics.
基金supported by the Fundamental Research Funds for the Central Non-profit Research Institution of the Chinese Academy of Forestry(Grant No.CAFYBB2019ZB007)the Biodiversity Survey and Assessment Project of the Ministry of Ecology and Environment,China(Grant No.2019HJ2096001006)+2 种基金the Ten Thousand Talent Program of Yunnan Province(Grant No.YNWRQNBJ-2019-010YNWR-QNBJ-2018-174)the Young and Middle-aged Academic and Technical Leader Reserve Talent Project of Yunnan Province(Grant No.2018HB066).
文摘Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations.In this study,we used double digest restriction-siteassociated DNA sequencing(ddRAD)technology to assess the genetic diversity,genetic structure and demographic history of the three extant populations of R.meddianum.Analysis of SNPs indicated that R.meddianum populations have a high genetic diversity(p?0.0772±0.0024,HE?0.0742±0.002).Both FST values(0.1582e0.2388)and AMOVA showed a moderate genetic differentiation among the R.meddianum populations.Meanwhile,STRUCTURE,PCoA and NJ trees indicated that the R.meddianum samples were clustered into three distinct genetic groups.Using the stairway plot,we found that R.meddianum underwent a population bottleneck about 70,000 years ago.Furthermore,demographic models of R.meddianum and its relative,Rhododendron cyanocarpum,revealed that these species diverged about 3.05(2.21e5.03)million years ago.This divergence may have been caused by environmental changes that occurred after the late Pliocene,e.g.,the Asian winter monsoon intensified,leading to a drier climate.Based on these findings,we recommend that R.meddianum be conserved through in situ,ex situ approaches and that its seeds be collected for germplasm.
基金supported by China National Science Foundation(No.32001166)the National Key Research and Development Program of China(No.2021YFD2200405)+1 种基金the Startup Foundation for Introducing Talent of NUIST(Nos.2019r059 and 003080)support from the Jiangsu Distinguished Professor program of the People’s Government of Jiangsu Province。
文摘Background: Tree demography is an essential indicator of various forest ecosystem services, and understanding its changes is critical for the sustainable management of forests. During the past four decades, China implemented unprecedented forest restoration projects, which altered tree demography by increasing the number of trees and introducing new species. However, it remains unclear how species composition has changed in China in response to the past forest restoration and demographical processes.Methods: We applied Forest Stability Index(FSI) and the relative change of FSI(%FSI) to describe the population dynamics of tree species and structure in China since 1998, using field-survey data collected from over 200,000plot-records from the 6th to 9th National Forest Inventories(NFIs).Results: The overall populations of both natural and planted forests have grown rapidly from 1998 to 2018, while the range of changes in the relative tree density was more variable for natural forests(ranging from-8.53% to42.46%) than for planted forests(ranging from-1.01% to 13.31%). The populations declined only in some of the tree species, including Betula platyphylla, Ulmus pumila, and Robinia pseudoacacia. In contrast, the populations of trees in the largest size-class either remained stable or expanded.Conclusions: Tree density of China?s forests(both natural and planted forests) generally expanded and the overall populations increased in most size classes, with greater increases occurred in planted forests. In contrasting to the global decline trends of large diameter trees, here we found no apparent decline for trees in the largest size-class in China, highlighting China?s success in improving forest health and forest adaptations to climate change. We advocate for more studies to reveal the mechanisms of the changes in tree demography, which will help to improve forest ecosystem services such as the carbon sequestration capacity.
文摘Recent advances in high-throughput sequencing technologies have revolutionized the field of population genetics. Data now routinely contain genomic level polymorphism information, and the low cost of DNA sequencing enables researchers to investigate tens of thousands of subjects at a time. This provides an unprecedented opportunity to address fundamental evolutionary questions, while posing challenges on traditional population genetic theories and methods. This review provides an overview of the recent methodological developments in the field of population genetics, specifically methods used to infer ancient population history and investigate natural selection using large-sample, large-scale genetic data. Several open questions are also discussed at the end of the review.
