Seventy Years of Diplomatic Achievements Since the Founding of the People’s Republic of China

The birth of the People’s Republic of China 70 years ago set China’s foreign relations on a momentous and dauntless journey.Under the leadership of the Communist Party of China(CPC),China’s foreign policy in the past seven decades has been focused on promoting national rejuvenation,domestic development and reform and opening-up,on safeguarding China’s sovereignty,security and development interests,and on maintaining world peace and bolstering common development.

Scaling up impact of malaria control programmes: a tale of events in Sub-Saharan Africa and People’s Republic of China

This review aims at providing synthetic information with scientific evidence on the trends in the malaria events from 1960 to 2011,with the hope that it will help policy makers to take informed decisions on public health issues and intervention designs on malaria control towards elimination in both Sub-Sahara Africa and in the People’s Republic of China by highlighting the achievements,progress and challenges in research on moving malaria from epidemic status towards elimination.Our findings showed that since 1960,malaria control programmes in most countries have been disjointed and not harmonized.Interestingly,during the last decade,the causal factors of the unprecedented and substantial decline in malaria morbidity and mortality rates in most vulnerable groups in these endemic areas are multifaceted,including not only the spread of malaria and its related effects but also political and financial willingness,commitment and funding by governments and international donors.The benefits of scaling up the impact of malaria coverage interventions,improvement of health system approaches and sustained commitment of stakeholders are highlighted,although considerable efforts are still necessary in Sub-Sahara Africa.Furthermore,novel integrated control strategies aiming at moving malaria from epidemic status to control towards elimination,require solid research priorities both for sustainability of the most efficient existing tools and intervention coverage,and in gaining more insights in the understanding of the epidemiology,pathogenesis,vector dynamics,and socioeconomic aspects of the disease.In conclusion,political commitment and financial investment of stakeholders in sustaining the scaling up impact of malaria control interventions,networking between African and Chinese scientists,and their Western partners are urgently needed in upholding the recent gains,and in translating lessons learnt from the Chinese malaria control achievements and successes into practical interventions in malaria endemic countries in Africa and elsewhere.

The genetic variation of Angiostrongylus cantonensis in the People’s Republic of China

Background:The People’s Republic of China(P.R.China)is the presumptive home range of the rat lungworm Angiostrongylus cantonensis,a major aetiological agent of human eosinophilic meningitis.We present a study of the genetic variation of A.cantonensis in P.R.China.Our aim was to deepen the current knowledge pertaining to its origin and global spread from a molecular perspective.Methods:Adult A.cantonensis were collected in the frame of a national survey and identified based on morphological criteria.Polymerase chain reaction(PCR)was employed to amplify the target DNA sequences(cytochrome c oxidase subunit I(cox1),nicotinamide adenine dinucleotide dehydrogenase subunit 1(nad1)and internal transcribed spacer(ITS)).The PCR product of cox1 was directly submitted to sequencing,while clone sequencing was used for nad1 and ITS.The identity of the samples was verified by comparing the sequences to those of accepted A.cantonensis specimens.The specific composition of substitutions in each gene was analysed,and the genotypes were compared based on the complete cox1,nad1 and ITS genes.Results:We characterised the complete mitochondrial genes cox1 and nad1 of 130 specimens and obtained 357 nuclear sequences containing two complete ITS(ITS1 and ITS2)and 5.8S rRNA of the same samples.All specimens were genetically confirmed as A.cantonensis.Two major groups(i.e.I and II)were identified according to the phylogeny of cox1 sequences.Group I could be further categorised into six distinct clades.Almost half of the specimens(47.7%)belong to the clade Ia and 22.3%to the group II.The former was widely distributed across the study region.A variable number of repeat units in three microsatellites was observed,resulting in considerable length variation in ITS.Intragenomic variation of ITS sequences was found in a large proportion of the samples.Genotyping showed a striking difference between mitochondrial DNA and ITS.Conclusions:Our results demonstrate that A.cantonensis is the only rat lungworm species in P.R.China and shows high genetic diversity.Results of diversity and genotyping of A.cantonensis can be impacted by the sequencing strategy and biomarker.Although ITS may be a valuable marker for interspecific identification,it is not suitable for studying the intraspecific variation of A.cantonensis due to its high intragenomic variation and current challenges for direct sequencing.

Knowledge of, attitudes towards, and practice relating to schistosomiasis in two subtypes of a mountainous region of the People’s Republic of China

Background:Schistosomiasis japonica is still endemic in the People’s Republic of China(P.R.China)in five provinces of lake and marshland regions and in two provinces of mountainous regions.Studies elucidated that individual and community perception,attitudes towards schistosomiasis,and hygiene behaviors were crucial factors for preventing schistosomiasis.This study sought to assess the knowledge of,attitudes towards,and practices(KAP)relating to schistosomiasis in two subtypes of a mountainous region in Eryuan County,Yunnan Province,P.R.China.The study’s aim is to make suggestions for establishing more specific and effective control measures for disease transmission and interruption in two subtypes of a mountainous region with low-level infection rates.Methods:A cross-sectional study of 3,000 inhabitants was carried out in the Yongle(plateau basin)and Xinzhuang(plateau canyon)communities of Eryuan County,Yunnan Province in November and December 2011.Stratified cluster random sampling was undertaken using a uniform set of quantitative questionnaires administered by trained assistants.This was further supported with qualitative data from in-depth interviews(IDIs)conducted with ten farmers and ten students.All participants were examined for schistosomiasis using both a serological test(indirect hemagglutination assay[IHA])and a stool examination(Kato-Katz).Results:The total schistosomiasis knowledge rate in Yongle(83.4%)was significantly lower than that in Xinzhuang(95.5%).In both communities,among the respondents aged 15 years or below,more than one third didn’t know the name,endemic areas,and animal reservoirs of schistosomiasis.The majority of respondents in Eryuan acquired their schistosomiasis knowledge from doctors,followed by handouts and hearing from others.The infection rate was once the highest in Yongle,but is now the highest in Xinzhuang,where there are more risk factors for schistosomiasis,such as frequently grazing cattle,digging vegetables or cutting grass in the field,as well as raising cattle by free grazing.Conclusion:In short,Eryuan County’s overall knowledge rate of schistosomiasis was found to be high.Due to various dominating risk factors,different control strategies should be designed keeping in mind the two different subtypes of endemic areas for schistosomiasis in mountainous regions,namely plateau basins and plateau canyons.

Spatial-temporal analysis of pulmonary tuberculosis in the northeast of the Yunnan province,People’s Republic of China

Background:The number of pulmonary tuberculosis(PTB)cases in China ranks third in the world.A continuous increase in cases has recently been recorded in Zhaotong prefecture-level city,which is located in the northeastern part of Yunnan province.This study explored the space-time dynamics of PTB cases in Zhaotong to provide useful information that will help guide policymakers to formulate effective regional prevention and control strategies.Methods:The data on PTB cases were extracted from the nationwide tuberculosis online registration system.Time series and spatial cluster analyses were applied to detect PTB temporal trends and spatial patterns at the town level between 2011 and 2015 in Zhaotong.Three indicators of PTB treatment registration history were used:initial treatment registration rate,re-treatment registration rate,and total PTB registration rate.Results:Seasonal trends were detected with an apparent symptom onset peak during the winter season and a registration peak during the spring season.A most likely cluster and six secondary clusters were identified for the total PTB registration rate,one most likely cluster and five secondary clusters for the initial treatment registration rate,and one most likely cluster for the re-treatment registration rate.The most likely cluster of the three indicators had a similar spatial distribution and size in Zhenxiong County,which is characterised by a poor socio-economic level and the largest population in Yunnan.Conclusion:This study identified temporal and spatial distribution of PTB in a high PTB burden area using existing health data.The results of the study provide useful information on the prevailing epidemiological situation of PTB in Zhaotong and could be used to develop strategies for more effective PTB control at the town level.The cluster that overlapped the three PTB indicators falls within the geographic areas where PTB control efforts should be prioritised.

Neglected tropical diseases in the People’s Republic of China: progress towards elimination

Since the founding of the People's Republic of China in 1949,considerable progress has been made in the control and elimination of the country's initial set of 11 neglected tropical diseases.Indeed,elimination as a public health problem has been declared for lymphatic filariasis in 2007 and for trachoma in 2015.The remaining numbers of people affected by soil-transmitted helminth infection,clonorchiasis,taeniasis,and echinococcosis in 2015 were 29.1 million,6.0 million,366200,and 166100,respectively.In 2017,after more than 60 years of uninterrupted,multifaceted schistosomiasis control,has seen the number of cases dwindling from more than 10 million to 37600.Meanwhile,about 6000 dengue cases are reported,while the incidence of leishmaniasis,leprosy,and rabies are down at 600 or fewer per year.Sustained social and economic development,going hand-in-hand with improvement of water,sanitation,and hygiene provide the foundation for continued progress,while rigorous surveillance and specific public health responses will consolidate achievements and shape the elimination agenda.Targets for poverty elimination and strategic plans and intervention packages post-2020 are important opportunities for further control and elimination,when remaining challenges call for sustainable efforts.

Research gaps for three main tropical diseases in the People’s Republic of China

This scoping review analyzes the research gaps of three diseases:schistosomiasis japonica,malaria and echinococcosis.Based on available data in the P.R.China,we highlight the gaps between control capacity and prevalence levels,and between diagnostic/drug development and population need for treatment at different stages of the national control programme.After reviewing the literature from 848 original studies and consultations with experts in the field,the gaps were identified as follows.Firstly,the malaria research gaps include(i)deficiency of active testing in the public community and no appropriate technique to evaluate elimination,(ii)lack of sensitive diagnostic tools for asymptomatic patients,(iii)lack of safe drugs for mass administration.Secondly,gaps in research of schistosomiasis include(i)incongruent policy in the implementation of integrated control strategy for schistosomiasis,(ii)lack of effective tools for Oncomelania sp.snail control,(iii)lack of a more sensitive and cheaper diagnostic test for large population samples,(iv)lack of new drugs in addition to praziquantel.Thirdly,gaps in research of echinococcosis include(i)low capacity in field epidemiology studies,(ii)lack of sanitation improvement studies in epidemic areas,(iii)lack of a sensitivity test for early diagnosis,(iv)lack of more effective drugs for short-term treatment.We believe these three diseases can eventually be eliminated in China's Mainland if all the research gaps are abridged in a short period of time.

Economic cost analysis of malaria case management at the household level during the malaria elimination phase in The People’s Republic of China

Background:In China,malaria has been posing a significant economic burden on households.To evaluate malaria economic burden in terms of both direct and indirect costs has its meaning in improving the effectiveness of malaria elimination program in China.Methods:A number of study sites(eight counties in five provinces)were selected from the malaria endemic area in China,representing the different levels of malaria incidence,risk classification,economic development.A number of households with malaria cases(n=923)were surveyed during the May to December in 2012 to collect information on malaria economic burden.Descriptive statistics were used to characterize the basic profiles of selected malaria cases in terms of their gender,age group,occupation and malaria type.The malaria economic costs were evaluated by direct and indirect costs.Comparisons were carried out by using the chi-square test(or Z-test)and the Mann-Whitney U test among malaria cases with reference to local/imported malaria patients,hospitalized/out patients,and treatment hospitals.Results:The average cost of malaria per case was 1691.23 CNY(direct cost was 735.41 CNY and indirect cost was 955.82 CNY),which accounted for 11.1%of a household’s total income.The average costs per case for local and imported malaria were 1087.58 CNY and 4271.93 CNY,respectively.The average cost of a malaria patient being diagnosed and treated in a hospital at the county level or above(3975.43 CNY)was 4.23 times higher than that of malaria patient being diagnosed and treated at a village or township hospital(938.80 CNY).Conclusion:This study found that malaria has been posing a significant economic burden on households in terms of direct and indirect costs.There is a need to improve the effectiveness of interventions in order to reduce the impact costs of malaria,especially of imported infections,in order to eliminate the disease in China.

Experiencing urban forests for mitigation of negative emotions of people exposed to seasonal PM_(2.5)in Northeast China

Experiencing urban green and blue spaces(GBSs)can be a nature-based solution to improve mental well-being and cope with negative moods for people exposed to PM2.5 pollution.In this study,a total of 1257 photos were collected to recognize their posted emotions of Sina Weibo users from 38 parks in 22 cities in Northeast China in 2021,when atmospheric PM_(2.5)and landscape metrics were evaluated for GBSs of each park.Autumn and winter had heavy atmospheric PM_(2.5)pollutions in resource-dependent cities of Liaoning.Net positive emotions(happy minus sad scores)decreased in larger green spaces.The perception of blue space countered the presentation of sadness only for a limited period over four seasons.High elevation decreased the level of happiness presented in winter.Overall,this study confirms that visiting large urban green spaces at low elevations can benefit the perception of positive sentiments for people exposed to PM_(2.5)in autumn.For planning urban forests in Northeast China,more green spaces should be constructed in cities in southern Jilin province to alleviate air PM_(2.5)pollution and gain better well-being of local people.

Climate-growth relationships of Pinus tabuliformis along an altitudinal gradient on Baiyunshan Mountain,Central China

A set of standard chronologies for tree-ring width(TRW),earlywood width(EWW)and latewood width(LWW)in Pinus tabuliformis Carr.along an altitudi-nal gradient(1450,1400,and 1350 m a.s.l.)on Baiyunshan Mountain,Central China to analyze the effect of varying temperature and precipitation on growth along the gradi-ent.Correlation analyses showed that at all three altitudes and the TRW and EWW chronologies generally had signifi-cant negative correlations with mean and maximum tem-peratures in the current April and May and with minimum temperatures in the prior July and August,but significant positive correlations with precipitation in the current May.Correlations were generally significantly negative between LWW chronologies and all temperatures in the prior July and August,indicating that the prior summer temperature had a strong lag effect on the growth of P.tabuliformis that increased with altitude.The correlation with the standard-ized precipitation evapotranspiration index(SPEI)confirmed that wet conditions in the current May promoted growth of TR and EW at all altitudes.Significant altitudinal differences were also found;at 1400 m,there were significant positive correlations between EWW chronologies and SPEI in the current April and significant negative correlations between LWW chronologies and SPEI in the current September,but these correlations were not significant at 1450 m.At 1350 m,there were also significant negative correlations between the TRW and the EWW chronologies and SPEI in the prior October and the current July and between LWW chronology and SPEI in the current August,but these cor-relations were not significant at 1400 m.Moving correlation results showed a stable response of EWW in relation to the SPEI in the current May at all three altitudes and of LWW to maximum temperature in the prior July-August at 1400 m from 2002 to 2018.The EWW chronology at 1400 m and the LWW chronology at 1450 m were identified as more suitable for climate reconstruction.These results provide a strong scientific basis for forest management decisions and climate reconstructions in Central China.

The late Early-Paleozoic granitic magmatism in Northwestern Fujian, China: constraints on intraplate orogeny in the South China block

The Early Paleozoic tectono-thermal event was a significant orogenic activity during the Phanerozoic era,which had a profound impact on the early crust of the South China Block(SCB) and established the foundation for later tectonic activity.The Wuyi-Yunkai orogenic belt in Southeastern China was extensively exposed to Early Paleozoic magmatism,the genetic mechanism of which remains controversial.To shed light on this issue,detailed petrological,geochemical,and zircon U-Pb-Hf isotopic studies were carried out on two granitoids,namely the Yuntongshan pluton and the Gaoqiao pluton,identified in the central Wuyishan.Zircon U-Pb chronology of the Yuntongshan and Gaoqiao bodies yielded ages of437±4 Ma(MSWD=2.2) and 404±2 Ma(MSWD=12),respectively,indicating that they were emplaced during the Early Silurian and Early Devonian periods.These granitoids are primarily composed of biotite-granite and biotite-monzonitic-granites,with high concentrations of S_(i)O_(2)(73.59-75.91 wt%),K_(2)O+Na_(2)O(8.31-8.73wt%),and low contents of MgO,CaO,Cr,Ni.They are classified as high-K calc-alkaline and weakly metaluminous-strongly peraluminous S-type granites.These granitoids are enriched in light rare earth elements(LREEs) and large ion lithophile elements(LILEs) and depleted in heavy rare earth elements(HREEs) and high field strength elements(HFSEs) with arc affinity.The εHf(t) values of-3.3 to-15.4 with two-stage Hf model ages ranging from 2829 to 1644 Ma,combined with the presence of Neoproterozoic inherited zircons,suggest that the primary magma of these granitoids was derived from the partial melting of Neoproterozoic crust with a Paleoproterozoic crustal model age.These findings,combined with the spatio-temporal distribution of regional magmatism,reveal that the late Early-Paleozoic granitoids formed in the intraplate orogenic background originating from the subduction of the proto-Tethys Ocean and proto-Pacific Ocean around the margin of the east Gondwana supercontinent.

Effects of urbanization and forest type on species composition and diversity,forest characteristics,biomass carbon sink,and their associations in Changchun,Northeast China:implications for urban carbon stock improvement

Differences in forest attributes and carbon sequestration of each organ and layer between broadleaved and conifer forests of central and outer urban areas are not well-defined,hindering the precise management of urban forests and improvement of function.To clarify the effect of two forest types with different urbanization intensities,we determined differences in vegetation composition and diversity,structural traits,and carbon stocks of 152 plots(20 m×20 m)in urban park forests in Changchun,which had the largest green quantity and carbon density effectiveness.We found that 1.1-fold thicker and healthier trees,and 1.6-to 2.0-fold higher,healthier,denser,and more various shrubs but with sparser trees and herbs occurred in the central urban forests(p<0.05)than in the outer forests.The conifer forests exhibited 30–70%obviously higher tree aboveground carbon sequestration(including stem and leaf)and 20%bigger trees,especially in the outer forests(p<0.05).In contrast,1.1-to 1.5-fold higher branch stocks,healthier and more diverse trees were found in broadleaved forests of both the inner and outer forests(p<0.05).Plant size and dominant species had similarly important roles in carbon stock improvement,especially big-sized woody plants and Pinus tabuliformis.In addition,a higher number of deciduous or needle species positively affected the broadleaved forest of the central urban area and conifer forest of the outer urban area,respectively.These findings can be used to guide precise management and accelerate the improvement of urban carbon function in Northeast China in the future.

Microenvironmental effects on growth response of Pinus massoniana to climate at its northern boundary in the Tongbai Mountains,Central China

The Tongbai Mountains is an ecologically sensi-tive region and the northern boundary of Pinus massoniana Lamb.To analyze the effect of different microenvironments on tree growth response to climate factors,we developed standard chronologies for earlywood width(EWW),late-wood width(LWW),and total ring width(TRW)of P.massoniana at two sampling sites on slopes with different orientations,then analyzed characteristics of the chronolo-gies and their correlations with climate variables from five stations in the region and with a regional normalized differ-ence vegetation index(NDVI).Statistical results showed that the TRW/EWW/LWW chronology consistency and charac-teristics(mean sensitivity,signal to noise ratio,expressed population signal)for trees growing on the southeastern slope were much higher than for trees on the northeastern slope.Correlations indicated that temperature in current March and August has a significant positive effect on TRW/EWW/LWW formation,and the effect on the northeastern slope was weaker than on the southeastern slope.Compared to temperature,precipitation has more complicated effects on tree growth,but the effect on the northeastern slope was also generally weaker than on the southeastern slope.Step-wise linear regression analyses showed that temperature in August was the main limiting factor at the two sampling sites.Similarly,the response of tree growth on the southeast-ern slope as determined by the NDVI is better than on the northeastern slope,and the TRW/EWW/LWW chronologies for the southeastern slope explained over 50%of the total NDVI variances in June.Overall,the results indicate that the difference in the climate response of P.massoniana at two sampling sites is clearly caused by differences in the microenvironment,and such differences should be properly considered in future studies of forest dynamics and climate reconstructions.

Soil bacterial and fungal communities resilience to long-term nitrogen addition in subtropical forests in China

Atmospheric nitrogen(N)deposition is predicted to increase,especially in the subtropics.However,the responses of soil microorganisms to long-term N addition at the molecular level in N-rich subtropical forests have not been clarified.A long-term nutrient addition experiment was conducted in a subtropical evergreen old-growth forest in China.The four treatments were:control,low N(50 kg N ha^(-1)a^(-1)),high N(100 kg N ha^(-1)a^(-1)),and combined N and phosphorus(P)(100 kg N ha^(-1)a^(-1)+50 kg P ha^(-1)a^(-1)).Metagenomic sequencing characterized diversity and composition of soil microbial communities and used to construct bacterial/fungal co-occurrence networks.Nutrient-treated soils were more acidic and had higher levels of dissolved organic carbon than controls.There were no significant differences in microbial diversity and community composition across treatments.The addition of nutrients increased the abundance of copiotrophic bacteria and potentially beneficial microorganisms(e.g.,Gemmatimonadetes,Chaetomium,and Aureobasidium).Low N addition increased microbiome network connectivity.Three rare fungi were identified as module hubs under nutrient addition,indicating that low abundance fungi were more sensitive to increased nutrients.The results indicate that the overall composition of microbial communities was stable but not static to long-term N addition.Our findings provide new insights that can aid predictions of the response of soil microbial communities to long-term N addition.

Stability assessment of tree ring growth of Pinus armandii Franch in response to climate change based on slope directions at the Lubanling in the Funiu Mountains,China

Global warming will affect growth strategies and how trees will adapt.To compare the response of tree radial growth to climate warming in different slope directions,samples of Pinus armandii Franch were collected and treering chronologies developed on northern and western slopes from the Lubanling in the Funiu Mountains.Correlation analyses showed that two chronologies were mainly limited by temperatures in the previous June–August and the combination of temperatures and moisture in the current May–July.The difference of the climate response to slopes was small but not negligible.Radial growth of the LBL01 site on the northern slope was affected by the combined maximum and minimum temperatures,while that of the LBL02 site was affected by maximum temperatures.With regards to moisture,radial growth of the trees on the north slope was influenced by the relative humidity in the current May–July,while on the western slope,it was affected by the relative humidity in the previous June–August,the current May–July and the precipitation in the current May–July.With the change in climate,the effects of the main limiting factors on growth on different slopes were visible to a certain extent,but the differences in response of trees on different slopes gradually decreased,which might be caused by factors such as different slope directions and the change in diurnal temperature range.These results may provide information for forest protection and ecological construction in this region,and a scientific reference for future climate reconstruction.

Overstory functional groups indicate the legacy of land use in a secondary tropical forest in southwestern China

Anthropogenic disturbances are widespread in tropical forests and influence the species composition in the overstory.However,the impacts of historical disturbance on tropical forest overstory recovery are unclear due to a lack of disturbance data,and previous studies have focused on understory species.In this study,the purpose was to deter-mine the influence of historical disturbance on the diver-sity,composition and regeneration of overstory species in present forests.In the 20-ha Xishuangbanna tropical sea-sonal rainforest dynamics plot in southwestern China,the historical disturbance boundaries were delineated based on panchromatic photographs from 1965.Factors that drove species clustering in the overstory layer(DBH≥40 cm)were analyzed and the abundance,richness and composition of these species were compared among different tree groups based on multiple regression tree analysis.The coefficient of variation of the brightness value in historical panchro-matic photographs from 1965 was the primary driver of spe-cies clustering in the overstory layer.The abundance and richness of overstory species throughout the regeneration process were similar,but species composition was always different.Although the proportion of large-seeded and vigorous-sprouting species showed no significant differ-ence between disturbed and undisturbed forests in the tree-let layer(DBH<20 cm),the difference became significant when DBH increased.The findings highlight that historical disturbances have strong legacy effects on functional group composition in the overstory and the recovery of overstory species was multidimensional.Functional group composi-tion can better indicate the dynamics of overstory species replacement during secondary succession.

Decline in tree-ring growth of Picea mongolica and its intra-annual eco-physiological responses to drought and CO_(2) enrichment in semi-arid China

Episodes of drought-induced decline in tree growth and mortality are becoming more frequent as a result of climate warming and enhanced water stress in semi-arid areas.However,the ecophysiological mechanisms under-lying the impact of drought on tree growth remains unre-solved.In this study,earlywood and latewood tree-ring growth,δ^(13)C,andδ^(18)O chronologies of Picea mongolica from 1900 to 2013 were developed to clarify the intra-and inter-annual tree-ring growth responses to increasingly fre-quent droughts.The results indicate that annual basal area increment residuals(BAI_(res)),which removed tree age and size effects,have significantly decreased since 1960.How-ever,the decreasing trend of earlywood BAI_(res) was higher than that of latewood.Climate response analysis suggests that the dominant parameters for earlywood and latewood proxies(BAI_(res),δ^(13)C andδ^(18)O)were drought-related climate variables(Palmer drought severity index,temperature,rela-tive humidity,and vapor pressure deficit).The most signifi-cant period of earlywood and latewood proxies’responses to climate variables were focused on June-July and July-August,respectively.BAI_(res),andδ^(13)C were significantly affected by temperature and moisture conditions,whereasδ^(18)O was slightly affected.Decreasing stomatal conduct-ance due to drought outweighed the influence of increasing CO_(2) on intrinsic water use efficiency(iWUE),and ultimately led to a decline in BAI_(res).Compared to latewood,the faster decreasing BAI_(res) and smaller increasing iWUE of early-wood suggested trees were more vulnerable to water stress in the early growing season.Our study provides insights into the inter-and intra-annual mechanisms of tree-ring growth in semi-arid regions under rising CO_(2) and climate change.

Temporal changes in mixing effects on litter decay and nitrogen release in a boreal riparian forest in northeastern China

In riparian forests,litter decay provides essential energy and nutrients for both terrestrial and fluvial ecosystems.Litter mixing effects(LMEs)are crucial in regulating litter decay and nutrient dynamics,yet how LMEs change over time is unclear in riparian forests.In this study,leaf litter of three common species(Alnus sibirica Fisch.ex Turcz,Betula platyphylla Sukaczev,and Betula fruticosa Pall.)were mixed in an equal mass ratio and LMEs were measured for mass and nitrogen(N)remaining in whole litter mixtures over a 3-year period in a boreal riparian forest,northeastern China.LMEs were also assessed for component litter mass and N remaining by separating litter mixtures by species.During the decay of litter mixtures,antagonistic effects on mass and N remaining were dominant after one and two years of decay,whereas only additive effects were observed after three years.LMEs correlated negatively with functional diversity after the first and two years of decay but disappeared after three years.When sorting litter mixtures by species,non-additive LMEs on mass and N remaining decreased over incubation time.Moreover,non-additive LMEs were more frequent for litter of both B.platyphylla and B.fruticosa with lower N concentration than for A.sibirica litter with higher N concentration.These results indicate that incubation time is a key determinant of litter mixing effects during decay and highlight that late-stage litter mixture decay may be predicted from single litter decay dynamics in boreal riparian forests.

April-September minimum temperature reconstruction based on Sabina tibetica ring-width chronology in the central eastern Tibetan Plateau,China

Minimum temperatures have remarkable impacts on tree growth at high-elevation sites on the Tibetan Plateau,but the shortage of long-term and high-resolution paleoclimate records inhibits understanding of recent minimum temperature anomalies.In this study,a warm season(April–September)reconstruction is presented for the past 467 years(1550–2016)based on Sabina tibetica ring-width chronology on the Lianbaoyeze Mountain of the central eastern Tibetan Plateau.Eight warm periods and eight cold periods were identified.Long-term minimum temperature variations revealed a high degree of coherence with nearby reconstructions.Spatial correlations between our reconstruction and global sea surface temperatures suggest that warm season minimum temperature anomalies in the central eastern Tibetan Plateau were strongly influenced by large-scale ocean atmospheric circulations,such as the El Ni?o-Southern Oscillation and the Atlantic Multidecadal Oscillation.

Winter-spring minimum temperature variations inferred from tree-ringδ13C in southeastern China

Long-term temperature variations inferred from high-resolution proxies provide an important context to evaluate the intensity of current warming.However,tem-perature reconstructions in humid southeastern China are scarce and particularly lack long-term data,limiting us to obtain a complete picture of regional temperature evolution.In this study,we present a well-verified reconstruction of winter-spring(January–April)minimum temperatures over southeastern China based on stable carbon isotopic(δ^(13)C)records of tree rings from Taxus wallichiana var.mairei from 1860 to 2014.This reconstruction accounted for 56.4%of the total observed variance.Cold periods occurred during the 1860s–1910s and 1960s–1970s.Although temperatures have had an upward trend since the 1920s,most of the cold extremes were in recent decades.The El Niño-Southern Oscillation(ENSO)variance acted as a key modulator of regional winter-spring minimum temperature variability.However,teleconnections between them were a nonlinear process,i.e.,a reduced or enhanced ENSO variance may result in a weakened or intensified temperature-ENSO relationship.