The cardiovascular system at high altitude:A bibliometric and visualization analysis

BACKGROUND When exposed to high-altitude environments,the cardiovascular system undergoes various changes,the performance and mechanisms of which remain controversial.AIM To summarize the latest research advancements and hot research points in the cardiovascular system at high altitude by conducting a bibliometric and visualization analysis.METHODS The literature was systematically retrieved and filtered using the Web of Science Core Collection of Science Citation Index Expanded.A visualization analysis of the identified publications was conducted employing CiteSpace and VOSviewer.RESULTS A total of 1674 publications were included in the study,with an observed annual increase in the number of publications spanning from 1990 to 2022.The United States of America emerged as the predominant contributor,while Universidad Peruana Cayetano Heredia stood out as the institution with the highest publication output.Notably,Jean-Paul Richalet demonstrated the highest productivity among researchers focusing on the cardiovascular system at high altitude.Furthermore,Peter Bärtsch emerged as the author with the highest number of cited articles.Keyword analysis identified hypoxia,exercise,acclimatization,acute and chronic mountain sickness,pulmonary hypertension,metabolism,and echocardiography as the primary research hot research points and emerging directions in the study of the cardiovascular system at high altitude.CONCLUSION Over the past 32 years,research on the cardiovascular system in high-altitude regions has been steadily increasing.Future research in this field may focus on areas such as hypoxia adaptation,metabolism,and cardiopulmonary exercise.Strengthening interdisciplinary and multi-team collaborations will facilitate further exploration of the pathophysiological mechanisms underlying cardiovascular changes in high-altitude environments and provide a theoretical basis for standardized disease diagnosis and treatment.

Effect of dissolved-oxygen on the flotation behavior of pyrite at high altitude area

With the continuous development of mineral resources to high altitude areas,the study of sulfide ore flotation in unconventional systems has been emphasized.There is a consensus that moderate oxidation of sulfide ore is beneficial to flotation,but the specific suitable dissolved oxygen value is inconclusive,and there are few studies on sulfide ore flotation under low dissolved oxygen environment at high altitude.In this paper,we designed and assembled an atmosphere simulation flotation equipment to simulate the flotation of pyrite at high altitude by controlling the partial pressure of N_(2)/O_(2) and dissolved oxygen under atmospheric conditions.X-ray photoelectron spec-troscopy(XPS),atomic force microscope(AFM),Fourier transform infrared spectrometer(FT-IR),UV-vis spectrophotometer,zeta po-tential,and contact angle measurements were used to reveal the effects of surface oxidation and agent adsorption on pyrite at high altitude(4600 m dissolved oxygen(DO)=4.0 mg/L).The results of pure mineral flotation indicated that the high altitude and low dissolved oxy-gen environment is favorable for pyrite flotation.Contact angle measurements and XPS analysis showed that the high altitude atmosphere nslows down the oxidation of pyrite surface,facilitates S_(n)^(2-)/S^(0) production and enhances surface hydrophobicity.Electrochemical calcula-tions and zeta potential analysis showed that the influence of atmosphere on the form of pyrite adsorption is small,and the different atmo-spheric conditions are consistent with dixanthogen electrochemical adsorption,with lower Zeta potential under high altitude atmosphere and significant potential shift after sodium isobutyl xanthate(SIBX)adsorption.The results of FT-IR,UV-vis,and AFM analysis showed that SIBX adsorbed more on the surface of pyrite under high altitude atmosphere and adsorbed on the surface in a mesh structure com-posed of column/block.The results of the experimental study revealed the reasons for the easy flotation of sulfide ores at high altitude with less collector dosage,and confirmed that the combined DO-pH regulation is beneficial to achieve more efficient flotation of pyrite.

Soil Physico-Chemical Properties and Different Altitudes Affect Arbuscular Mycorrhizal Fungi Abundance and Colonization in Cacao Plantations of Cameroon

This study aims to investigate the abundance of AMF according to soil properties and altitudes in different cacao plantations of Cameroon. Physico-chemical analyses were made on soil samples collected from three agro-ecological zones. Soil samples were also used to evaluate directly the AMF abundance following the various altitudes and after trapping by sorghum plant. The results showed that soil properties, AMF spore abundances and colonization fluctuated significantly at different altitudes. The most represented texture was sandy loam. The bimodal zone presented a homogeneous texture (sandy loam) in all its localities. Cacao soil chemical characteristics showed that, the highest nitrogen rate (0.47%;p 0.05, Scott-Knott test) was recorded at Melong in a monomodal zone while Tonga in the Western highlands displayed the lowest rate (0.13%). Soil P concentration was significantly high in monomodal zones (Mbanga and Melong). Soil pH level indicated that the soil from Tonga in the Western highlands was neutral (pH = 6.67), and soils of other localities under study were acidic with the lowest (4.75) pH level recorded at Melong in a monomodal zone. In soil samples, the highest spore density (1.03 spores/g soil) was observed at Ntui in Bimodal zone, while the lowest spore density (0.26 spores/g soil) was observed at Bafang in the Western highlands. Root colonization showed that the sample from Bokito in a bimodal zone displayed the best frequency of mycorrhization (86.11%) while the sample from Bafang in the Western highlands recorded the lowest (27.11%). The PCA analysis highlighted that available phosphorus, pH and altitude all strongly correlated with AMF root colonization ability and can be used as a predictor of AMF colonization ability in cacao rhizosphere.

Overview of radar detection methods for low altitude targets in marine environments

In this paper,a comprehensive overview of radar detection methods for low-altitude targets in maritime environments is presented,focusing on the challenges posed by sea clutter and multipath scattering.The performance of the radar detection methods under sea clutter,multipath,and combined conditions is categorized and summarized,and future research directions are outlined to enhance radar detection performance for low-altitude targets in maritime environments.

The characteristics of negative corona discharge and radio interference at different altitudes based on coaxial wire-cylinder gap

The corona discharge from transmission lines in high-altitude areas is more severe than at lower altitudes. The radio interference caused thereby is a key factor to be considered when designing transmission lines. To study the influence of altitude on negative corona characteristics, an experimental platform comprising a movable small corona cage was established: experiments were conducted at four altitudes in the range of 1120-4320 m, and data on the corona current pulse and radio interference level of 0.8-mm diameter fine copper wire under different negative voltages were collected. The experimental results show that the average amplitude, repetition frequency and average current of the corona current pulse increase with increasing altitude. The dispersion of pulse amplitude increases with increase in altitude, while the randomness of the pulse interval decreases continuously. Taking the average current as an intermediate variable,the relationship between radio interference level and altitude is obtained. The result of this research has some significance for understanding the corona discharge characteristics of ultra-highvoltage lines.

Increased CO2 Levels during the First Half of Incubation at High Altitude Modifies Embryonic Development of Fertile Leghorn Breeder Eggs

The exchange of oxygen (O2) and carbon dioxide (CO2) within an incubator has a significant impact on embryonic development (ED) and hatching processes. This study examines the influence of non-ventilation (NV) conditions during the first ten days of incubation at high altitudes on Leghorn hens hatching eggs. Five hundred four hatching eggs were equally divided into three treatment groups and placed in twelve incubators (R = 4). The first group was subjected to standard ventilated conditions (V) during the setting phase. The ventilation inlet holes of the remaining incubators in the NV treatments were closed with either micropore (M) or polypropylene (P) tape, referred to as NVM and NVP groups, respectively. These two different airtight settings were intended to allow for a gradual rise in CO2 naturally generated by the embryos. Results indicate that carbon dioxide concentration gradually increased during the first half of incubation, reaching 1.42% in the NVM group and 1.20% in the NVP group, while the V condition group remained at 0.15%. From 10 days of incubation onwards, normal V conditions were restored in all incubators. The highest hatchability of fertile eggs (HFE) was shown by the NVP group (55.7%), followed by the V (52.6%) and NVM (38.6%) groups. The NVP group showed a greater yolk-free body mass (YFBM) from 10 days of incubation until the hatch basket transfer. NV conditions during the first 10 days of incubation at high altitude produced higher YFBM with gradually decreasing yolk sac mass. In comparison to the NVM and V conditions, the particular NVP condition showed a beneficial impact on the quality of hatched chicks. Sustaining NVP condition (1.2% of CO2) throughout the first half of incubation at high altitude generated the optimal environment in the incubator ensuring the best hatchability results. This study highlights how important it is for hatchery managers to recognize the influence of low O2 and high levels of CO2 on the development trajectories of Leghorn embryos during early incubation at high altitudes.

Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude analysis.In this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 m.The experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical power.The duration of the dark period and the critical charge of streamer-toleader transition were obtained at high altitude.Based on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader transition.Compared with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified model.From the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

Physicochemical composition and climate response of surface sediments at different altitudes in Motuo on the southern slope of the Himalayas

Background,aim,and scope Certain physicochemical indexes of topsoil are closely related to climatic factors including temperature,and precipitation.Understanding the relationship between modern topsoil properties and climatic factors is essential for quantitative paleoclimate reconstruction.Motuo located in the eastern Himalayas,exhibits a significant elevation gradient of over 7000 m from Nnamjagbarwa Peak(7782 m a.s.l.)to the Baxika(150 m a.s.l.).This region features a complete vertical zonation of vegetation,from alpine meadow to tropical forest,presenting an ideal place to investigate the relationships among vegetation,soil and climate conditions across altitudinal gradients.This study aims to explore the vertical variations in the physicochemical composition of topsoil and its relationship with temperature and precipitation.Materials and methods Twenty-seven topsoil samples were collected at 100 m intervals from 800 m to 3600 m a.s.l.along the southern slope of the Himalayas.Grain size,magnetic susceptibility and geochemical elements were measured to discuss the vertical variation characteristics of topsoil composition and their correlation with climatic factors.Results(1)The grain size of topsoil at different altitudes in Motuo is mainly composed of sand accounting for an averaged 53.2%,followed by silt and clay.(2)In the mixed forest zone,frequency dependent magnetic susceptibility(χfd%)shows a clear relationship with altitude,and clay is positively correlated with both altitude and climatic factors.(3)The oxides of topsoil in this area mainly consist of SiO_(2),Al_(2)O_(3) and Fe_(2)O_(3),followed by MgO,CaO,Na_(2)O and K_(2)O,with slight variations in the primary components at different altitudes.The sensitivity of elements to climate varies across different altitudes and vegetation zone,likely due to the region’s complex topography and vegetation.(4)Physical and biological weathering dominates in the broad-leaved forest zone of Motuo,while chemical weathering is more prominent in the coniferous forest zone,with the mixed forest zone falling in between.Discussion The formation of topsoil across the three vegetation zones is influenced by various factors,including parent material,vegetation,and climate.In the broad-leaved forest zone,physical weathering(precipitation,root wedging etc.)and pedogenesis dominate,resulting in finer grain size.The χ_(fd)% increases with altitude likely due to the high temperature and abundant precipitation in this zone,which facilitate the transformation of strong magnetic miners into weaker ones,particularly when the soil is oversaturated.Zirconium(Zr),primarily found in zircon,is depleted at lower altitudes by strong current erosion.Barium(Ba)is similarly reduced at low altitudes in this zone.In mixed forest zone,clay content is the lowest,indicating weaker physical weathering conditions than broad-leaved forest zone.The coarser grain size may result from the combined effects of topography and vegetation coverage.Magnetic susceptibility and organic matter show a positive correlation with altitude.Zr concentration is higher than that in the broad-leaved forest zone,likely resulting from decreased precipitation.In the coniferous zone,the clay content shows considerable fluctuations,with grain size generally becoming finer as altitude increases.This trend may be explained by intensified soil disintegration from seasonal freeze-thaw cycles.The χ_(fd)% values lack a clear trend or pattern,possibly due to soil erosion causing the migration of magnetic minerals or insufficient iron precipitation,which reduces the concentration of magnetic minerals in the soil.Additionally,a positive correlation is observed between altitude and organic matter content,with higher altitudes associated with greater organic matter accumulation.This may be attributed to lower microbial activity in colder conditions,which slows the decomposition and transformation of organic matter.Conclusions The variations in grain size,magnetic susceptibility,and geochemical elements differ across altitudes and vegetation zones,closely connected to the complex interplay of terrain,vegetation,and climate in Motuo.In the mixed forest,altitude has a significant impact onχfd%,and the clay component is particularly sensitive to changes in altitude,mean annual temperature,and precipitation.Zr shows a strong correlation with altitude and climate factors,making it a valuable indicator for assessing changes in atmospheric precipitation within specific altitude ranges.Recommendations and perspectives This study enhances our understanding of the relationships between the physicochemical properties of topsoil and climate conditions,offering valuable insights for paleoclimate reconstruction in Motuo.

China Seeks to Grab Opportunities Brought about by the Low-Altitude Economy

Since the inclusion of the low-altitude economy in the government work report during the National People’s Congress and the Chinese People’s Political Consultative Conference in March,many cities have sought to enter this area first to seize the benefits of the low-altitude economy.According to incomplete statistics,17 provinces(municipalities,autonomous regions)in China have currently written the low-altitude economy into their 2024 government work report.In addition,cities such as Shenzhen,Guangzhou,Chengdu,Suzhou,Zhuhai,and Ganzhou have also included the low-altitude economy in their government work reports.More than 20 provincial and municipal governments,represented by Shenzhen,Hefei,Guangzhou and Chengdu,have introduced also policies to support the development of the low-altitude economy and its business ecosystem.

Differential pressure difference based altitude control of a stratospheric satellite

An autonomous altitude adjustment system for a stratospheric satellite(StratoSat)platform is proposed.This platform consists of a helium balloon,a ballonet,and a two-way blower.The helium balloon generates lift to balance the platform gravity.The two-way blower inflates and deflates the ballonet to regulate the buoyancy.Altitude adjustment is achieved by tracking the differential pressure difference(DPD),and a threshold switching strategy is used to achieve blower flow control.The vertical acceleration regulation ability is decided not only by the blower flow rate,but also by the designed margin of pressure difference(MPD).Pressure difference is a slow-varying variable compared with altitude,and it is adopted as the control variable.The response speed of the actuator to disturbance can be delayed,and the overshoot caused by the large inertia of the platform is inhibited.This method can maintain a high tracking accuracy and reduce the complexity of model calculation,thus improving the robustness of controller design.

Study on Skin Care Efficacy of the Active Ingredients in Camellia Japonica Flowers at High and Low Altitudes

The active ingredients of Camellia japonica flowers(CJF)at high and low altitudes,as well as their skin care efficacy were compared.The dried red CJF at high and low altitudes were ultrasonically extracted with 70%ethanol,and these extracts were concentrated and then diluted to a constant volume.The content of total flavonoids,total polyphenols and total proteins was tested and analyzed.In addition,DPPH free radical scavenging,inhibition of the formation of advanced glycation end products,and inhibitory activity against elastase was measured to compare their skin care efficacy in anti-oxidation,anti-glycation,anti-wrinkling and firming.The results showed that,based on the dry weight of CJF,the content of total flavonoids and total proteins of the CJF at high altitude was approximately 1.5 times of the CJF at low altitude,while the content of total polyphenols was approximately 2.4 times that of the CJF at low altitude.The skin care efficacy of CJF at high altitude was significantly better than that of the CJF at low altitude.This work could provide theoretical basis for the selection and application of Camellia japonica flowers in the field of cosmetics.

Research on the distribution characteristics of explosive shock waves at different altitudes

There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes.At present,there are many studies on plain explosion shock waves,but there are few studies on the distribution characteristics of plateau explosion shock waves,and there is still a lack of complete analysis and evaluation methods.This paper compares and analyzes shock wave overpressure data at different altitudes,obtains the attenuation effect of different altitudes on the shock wave propagation process and proposes a calculation formula for shock wave overpressure considering the effect of altitude.The data analysis results show that at the same TNT equivalent and the same distance from the measuring point,the shock wave overpressure at high altitude is lower than that at low altitude.With the increase in the explosion center distance of the measuring point,the peak attenuation rate of the shock wave overpressure at high altitudes is smaller than that at low altitudes,and the peak attenuation rate of the shock wave overpressure at high altitudes gradually intensifies with increasing proportional distance.The average error between the shock wave overpressure and measured shock wave overpressure in a high-altitude environment obtained by using the above calculation formula is 11.1389%.Therefore,this method can effectively predict explosion shock wave overpressure in plateau environments and provides an effective calculation method for practical engineering tests.

Effects of altitude hypoxia on contents of TXB_2, 6-keto-PGF_(1α) and LENK and their correlations with lung injury induced by pyosepticemia

Objective: To explore the effects of altitude hypoxia on septic pulmonary injury (3080 m above sea level). Methods : A model of pyosepticemia was established by cecal ligation and puncture. Thromboxane A2 (TXA2),prostacyclin (PGI2) of the venous plasma and leucine-enkephalins (L-ENK) in the arterial walls were measured using radioiizimunoassay in 31 rabbits. Mouse morrality was observed. Results: 24 h mouse accumulative mortality (97. 1% )was greater than that of control (35%). TXB2 content was 4 times as much as in control group and 6-keto-PGF1α level was elevated too. These changes of arachidonic metabolism could be blorked by indomethacin. The contents of LENK in arterial walls of puhiionary, mesenteric and renal arteries dropped significantly in comparison with control group (P<0. 01 ). The albumin content in the bronchoalveolar lavage fluid rase significantly in comparison with control group (P<0. 01 ). Conclusion : The results demonstrate that the metabolites of cyclcoxygenase are not the major mediator of puhiionary permeability in the experiment. The alteration of TXA2 and L-ENK contents may be one of the mechanisms, by which the puhiionary artery pressure and pulmonary vascular resistance are increased during sepsis.

ANTI-HYPOXIA AND ANTI-OXIDATION EFFECTS OF AMINOPHYLLINE ON HUMAN WITH ACUTE HIGH-ALTITUDE EXPOSURE

Objective To investigate the anti-hypoxia and anti-oxidation effects of aminophylline on human with acute high- altitude exposure. Mothoda Totally 100 young male army members newly recruited from Sichuan province （400 meters above sea level） were enrolled. They were randomly divided into two groups： 50 in aminophylline group （A group） and 50 in control group （ C group）. A group and C group orally took aminophylline and placebo respectively for 10 days, 7 days before entering Lhasa （3 658 meters above sea level） by air and 3 days after it. Several parameters were measured at three time points： before drug taken, 7 days after drug taken, and 3 days after ascending high altitude. These parameters included serum levels of nitric oxide （NO）, superoxide dismutase （SOD）, catalase （CAT）, hydrogen dioxide （H2O2）, lactic acid （LA）, as well as arterial oxygen saturation （SO2）, arterial oxygen partial pressure （PaO2）, and arterial carbon dioxide partial pressure （PaCO2）. Statistical analysis was conducted to compare the difference between two groups with Stata 7.0 software system. Results There were no statistical differences between groups in hypoxia and oxidation indicators before and after drug taken in plain area. Three days after ascending high altitude, the serum levels of SOD, CAT, H202, LA, PaCO2 increased in both groups, yet to a much larger degree in C group than A group （P 〈0. 01 ） ; and NO, SO2 , PaO2 decreased more markedly in C group （ P 〈 0. 05 for NO, P 〈 0. 0001 for SO2 and PaO2 ）. Conclusion Aminophylline has significant anti-hypoxia and anti-oxidation effects at high altitude.

Genes for the high life： New genetic variants point to positive selection for high altitude hypoxia in Tibetans

People living on the high plateaus of the world have long fascinated biological anthropologists and geneticists because they live in ＂thin air＂ and epitomize an extreme of human biological adaptation.

A rat model of high altitude polycythemia rapidly established by hypobaric hypoxia exposure

Objective To investigate the effects of simple hypobaric hypoxia on parameters of hematology and blood rheology in order to establish a rat model of simulated high altitude polycythemia(HAPC) for the study of pathophysiologic mechanisms and medical prevention and treatment of HAPC.Methods Fortyeight male Wistar rats were randomly divided into three normal control groups and three hypoxia model groups.Normal control group rats were bred in normoxia conditions,and hypoxia group rats were subjected to hypoxic exposure for 8 hours per day at simulated 5 500 m high altitude in a hypobaric chamber.After hypoxic exposure for 2,4,12 weeks,one group of normal control and hypoxia model rats were killed and blood was collected,respectively.Then parameters of erythrocyte and blood rheology were examined.Results Mucous membrane of hypoxia model rats showed obviously cyanosis after 2 weeks hypoxic exposure.Hemoglobin concentration of hypoxia model rats were beyond 210 g/L after 2 weeks,4 weeks and 12 weeks hypoxia exposure and significantly increased than that of normal control rats respectively.Besides,RBC counts,hematocrit,whole blood viscosity,erythrocyte aggregation index of hypoxia model rats were all notably higher than those of normal control rats respectively.Conclusion A rat model of high altitude polycythemia can be rapidly established by hypobaric hypoxia exposure at simulated 5 500 m high altitude for 8 hours daily.

High-altitude hypoxia induces disorders of the brain- endocrine-immune network through activation of corticotropin-releasing factor and its type- 1 receptors

High-altitude hypoxia can induce physiological dysfunction and mountain sickness,but the underlying mechanism is not fully understood.Corticotrophin-releasing factor(CRF) and CRF type-1 receptors(CRFR1) are members of the CRF family and the essential controllers of the physiological activity of the hypothalamo-pituitary-adrenal(HPA) axis and modulators of endocrine and behavioral activity in response to various stressors.We have previously found that high-altitude hypoxia induces disorders of the brain-endocrine-immune network through activation of CRF and CRFR1 in the brain and periphery that include activation of the HPA axis in a time-and dose-dependent manner,impaired or improved learning and memory,and anxiety-like behavioral change.Meanwhile,hypoxia induces dysfunctions of the hypothalamo-pituitary-endocrine and immune systems,including suppression of growth and development,as well as inhibition of reproductive,metabolic and immune functions.In contrast,the small mammals that live on the Qinghai-Tibet Plateau alpine meadow display low responsiveness to extreme high-altitudehypoxia challenge,suggesting well-acclimatized genes and a physiological strategy that developed during evolution through interactions between the genes and environment.All the findings provide evidence for understanding the neuroendocrine mechanisms of hypoxia-induced physiological dysfunction.This review extends these findings.

A Strategy to Control the Turbocharger Energy of a Diesel Engine at Different Altitudes

Power deterioration is a major problem for diesel engines operating at high altitudes.This problem stems from the limited availability of turbocharger energy,which is not enough to increase the boost pressure to the required level.In this study,a control strategy is introduced in order to achieve engine power recovery at different altitudes.It is shown that as the altitude increases from 0 to 4500 m,the required boost pressure ratio increases from 2.4 to 4.3.The needed turbocharger energy should be increased accordingly by 240%,and the TCC(turbine characterization coefficient)should be adjusted within wide ranges.A 12%decrease in the TCC can lead to a rise of the intake air pressure,which can compensate the pressure decrease due to a 1000 m altitude increase.The fluctuation range of boost pressure was within 14.5 kPa for variations in altitude from 0 to 4500 m.

Characteristics of Leaf Epidermis of 22 Lilieae (Liliaceae) under Different Altitudes in China

In this study, 22 leaf samples of 22 Lilieae species were collected in six Province at 90 - 3740 m to study the variations of leaf characteristics with altitude change. The Qualitative character of leaf epidermis and two stomatal indexes, viz. stomatal area (SA), stomatal index (SI), were analyzed in laboratory. The results show that: 1) the shape of the leaf epidermis cells and the pattern of the anticlinal walls provide some useful taxonomic information to distinguish the genus, however, none of the stable traits are exclusive to a genus;2) there are significant or even very significant linear correlations between the two indexes and altitude, of which SA exhibit a negative correlation with altitude (r2 = 0.294, p = 0.009), while SI exhibit a positive correlation with altitude (r2 = -0.254, p = 0.017). As a result, the pattern of leaf cells and anticlinal walls is influenced by genetic factors, while the stomatal area and stomatal index are influenced by environmental factors. Members of the tribe Lilieae have a relatively stable elevation range, which is related to their long-term adaptation to the local environment in the structure of their leaf epidermis.

Altitude shape genetic and phenotypic variations in growth curve parameters of Larix kaempferi

To study the effects of geoclimatic variables of provenances on growth phenotypes and selected plus provenances,over 3000 trees of 22-year-old Larix kaempferi were evaluated from trials established in two climate zones for provenance selection and to explore the influence of climate variables on provenance performance.The material was replicated plantings of 84 open pollinated families from six provenances distributed in the mountains of central Japan.Provenance variation was observed in most age groups and the heritability of growth traits showed large differences.The phenotypic maximum value of height and diameter were significantly positive with altitude,and mean annual precipitation being important factors.Diameter at breast height growth was significantly negative with altitude and spring rainfall.The Ina provenance of relatively high altitudes,was well adapted to a variety of climates.Altitude might be the driving force for phenotypic and genetic variations and local adaptation.