Low-altitude Regions Research Articles

Application of a Modified Ecological Quality Monitoring Method in the Southeastern Hilly Region of China

The southeastern hilly region of China is ecologically significant but highly vulnerable to climate change and human activities. This study developed a Modified Remote Sensing Ecological Index (MRSEI) using satellite imagery and Human Footprint data to assess ecological quality across 14 cities surrounding the Wuyi Mountains. We applied Sen’s slope analysis, the Mann–Kendall test, and spatial autocorrelation to evaluate spatiotemporal ecological changes from 2000 to 2020, and used partial correlation analysis to explore the drivers of these changes. The main findings are as follows: (1) Ecological quality generally improved over the study period, with significant year-to-year fluctuations. The eastern region, characterized by higher altitudes, consistently exhibited better ecological quality than the western region. The area of low-quality ecological zones significantly decreased, while Ji’an, Ganzhou, Heyuan, and Meizhou saw the most notable improvements. In contrast, urban areas experienced a marked decline in ecological quality. (2) The region is undergoing warming and wetting trends. Increased precipitation, especially in the western and northern regions, improved ecological quality, except in urban areas, where it heightened flood risks. Rising temperatures had mixed effects: they enhanced ecological quality in high-altitude areas (~516 m) but negatively impacted low-altitude regions (~262 m) due to intensified heat stress. (3) Although industrial restructuring reduced environmental pressure, rapid population growth and urban expansion created new ecological challenges. This study provides an innovative method for the ecological monitoring of hilly regions, effectively integrating human activity and climatic factors into ecological assessments. The findings offer valuable insights for sustainable development and ecological management in similar sensitive regions.

Improving mechanization conditions or encouraging non-grain crop production? Strategies for mitigating farmland abandonment in China’s mountainous areas

Food security is a critical global issue, requiring that the challenges of farmland abandonment be addressed. As a vital component of agricultural production in China, farmland use is affected by mechanization conditions and the crop cultivation decisions of rural households. With the decreasing economic viability of farmland in China’s mountainous areas, the effects of mechanization conditions and non-grain crop production on farmland abandonment remain controversial. This study developed a theoretical framework and used unique survey data from 2400 rural households in China’s mountainous areas to analyze the relationship between mechanization conditions, non-grain crop production, and farmland abandonment using multiple models, heterogeneity analysis, and factual characteristics analysis. These findings demonstrate that improving mechanization conditions and encouraging non-grain crop production could mitigate farmland abandonment. Non-grain crop production could mitigate abandonment through increasing agricultural labor input, and improving mechanization conditions could inhibit non-grain crop production. Additionally, improving mechanization conditions had a more significant effect on households with higher education level and lower incomes, while encouraging non-grain crop production showed an opposite trend. Both measures had greater effect in the western and low-altitude regions. Therefore, to protect farmland and ensure food security in mountainous areas, it is necessary to continue land consolidation appropriately, actively encourage non-grain crop production, and comprehensively balance the demands of different management objectives.

Spatiotemporal prediction of alpine wetlands under multi-climate scenarios in the west of Sichuan, China.

The alpine wetlands in western Sichuan are distributed along the eastern section of the Qinghai-Tibet Plateau (QTP), where the ecological environment is fragile and highly sensitive to global climate change. These wetlands are already experiencing severe ecological and environmental issues, such as drought, retrogressive succession, and desertification. However, due to the limitations of computational models, previous studies have been unable to adequately understand the spatiotemporal change trends of these alpine wetlands. We employed a large sample and composite supervised classification algorithms to classify alpine wetlands and generate wetland maps, based on the Google Earth Engine cloud computing platform. The thematic maps were then grid-sampled for predictive modeling of future wetland changes. Four species distribution models (SDMs), BIOCLIM, DOMAIN, MAXENT, and GARP were innovatively introduced. Using the WorldClim dataset as environmental variables, we predicted the future distribution of wetlands in western Sichuan under multiple climate scenarios. The Kappa coefficients for Landsat 8 and Sentinel 2 were 0.89 and 0.91, respectively. Among the four SDMs, MAXENT achieved a higher accuracy (α = 91.6%) for the actual wetland compared to the thematic overlay analysis. The area under the curve (AUC) of the MAXENT model simulations for wetland spatial distribution were all greater than 0.80. This suggests that incorporating the SDM model into land change simulations has high generalizability and significant advantages on a large scale. Furthermore, simulation results reveal that between 2021 and 2100 years, with increasing emission concentrations, highly suitable areas for wetland development exhibit significant spatial differentiation. In particular, wetland areas in high-altitude regions are expected to increase, while low-altitude regions will markedly shrink. The changes in the future spatial distribution of wetlands show a high level of consistency with historical climate changes, with warming being the main driving force behind the spatiotemporal changes in alpine wetlands in western Sichuan, especially evident in the central high-altitude and northern low-altitude areas.

Metagenomics and selective culture reveal the major transfer and prevalence of antibiotic resistance genes in Tibetan Plateau animals

The Tibetan Plateau, despite being the highest and least populated plateau on the Earth, harbors antibiotic-resistant bacteria (ARBs) as well as antibiotic resistance genes (ARGs) in its pristine environment and animals. There is, however, limited knowledge regarding antibiotic resistance in Tibetan Plateau animals. Here, fecal samples of grazing yaks and intestinal content samples of wild rats were collected at altitudes of 2920m and 4360m and subjected to selective culture, PCR, and metagenomic sequencing. The results revealed a higher antibiotic resistance rate in low-altitude regions than in high-altitude regions. The simultaneous presence of bacteria exhibiting different antibiotic resistance phenotypes across multiple samples suggests the potential emergence of multidrug-resistant strains within the animal gut microbiota. Pseudomonas spp. and Escherichia coli were the predominant ARBs. In contrast to low-altitude regions with frequent human activities, ARG dissemination in the Tibetan Plateau did not show a significant correlation with mobile genetic elements. ARGs in high-altitude regions relied more on vertical gene transmission. This study expands our knowledge of antibiotic resistance in grazing and wild animals inhabiting the Tibetan Plateau, thereby highlighting the potential threat posed by antibiotic resistance in this region.

DDIT4 promotes erythroid differentiation and coordinates with SIPA1 to regulate erythroid proliferation in bone marrow of high altitude erythrocytosis

Erythrocytosis moderately enhances the oxygen-carrying capacity of the blood and is considered a characteristic response of individuals adapting from low-altitude regions to high-altitude regions. Nevertheless, erythrocytosis can also turn excessive and result in maladaptive syndromes, such as high altitude polycythemia (HAPC). The increased differentiation or proliferation of erythroid cells in the bone marrow may be a crucial factor leading to accumulation of peripheral erythroid cells. However, the mechanism of erythroid regulation within the bone marrow of high-altitude erythrocytosis remains insufficiently systematically observed. We utilized single-cell transcription sequencing to characterize bone marrow cells following chronic hypoxic exposure and found that bone marrow erythrocytosis is associated with the accumulation of Baso-E, Poly-E, and Ortho-E cells at the terminal stage of erythroid lineage differentiation. Through analysis of differential gene expression and localization in differentiated cells within the erythroid lineage, we confirmed that DDIT4 expression was localized in advanced differentiated erythroblast including Baso-E, Poly-E and Ortho-E, its expression was significantly enhanced by hypoxia exposure. We demonstrated that overexpression of DDIT4 could promote K562 cell differentiation, and through the IP pull-down interaction protein profile, we found that DDIT4 might participate in regulating the cell cycle by interacting with SIPA1 to promote the proliferation of erythroid cells and may be involved in HAPC.

Comparison of Three Remote Sensing Indices in Revealing the Vegetation Growth Dynamics in Nepal from 2000 to 2020

Remote sensing indices have been widely used to monitor the vegetation growth dynamics induced by climate change and human activities, and yet the consistency of the vegetation dynamics revealed by different remote sensing indices in mountains is unclear. Using Nepal as a case study, this study explored the spatial-termporal consistencies of the three widely-used remote sensing indices （i.e., normalized difference vegetation index （NDVI）, leaf area index （LAI）, and net primary production （NPP）） in quantifying the vegetation growth dynamics in mountainous regions. The results indicated that the spatial distributions of the multi-year mean estimates varied greatly by remote sensing index, especially in the low-altitude regions. The maximum NDVI, LAI, and NPP occurred in the low, medium, and high mountain regions, respectively. Although all three indices showed an overall increasing tendency from a long-term perspective, the area percentage of the lands with a significant trend was obviously larger in NDVI （82%） than that in NPP （58%） and LAI （56%）. In addition, the land area percentages with vegetation growth enhancement decreased gradually by the rise of altitude for both the NDVI and LAI indices but decreased after an increase for the NPP index. Only 9.6% of the lands showed consistent long-term trends （with the same change directions and significant levels） in the three indices on a per-pixel basis. Our findings highlight the large uncertainties of remote sensing indices in monitoring vegetation growth dynamics in mountainous areas, and the importance of developing reinforced remote sensing products in future efforts.

Impacts of elevated anthropogenic emissions on physicochemical characteristics of black-carbon-containing particles over the Tibetan Plateau

Abstract. Black carbon (BC) in the Tibetan Plateau (TP) region has distinct climate effects that strongly depend on its mixing state. The aging processes of BC in the TP are subject to emissions from various regions, resulting in considerable variability of its mixing state and physicochemical properties. However, the mechanism and magnitude of this effect are not yet clear. In this study, field observations on physicochemical properties of BC-containing particles (PMBC) were conducted in the northeast (Xihai) and southeast (Lulang) regions of the TP to investigate the impacts of transported emissions from lower-altitude areas on BC characteristics in the TP. Large spatial discrepancies were found in the chemical composition of PMBC. Both sites showed higher concentrations of PMBC when they were affected by transported air masses outside the TP but with diverse chemical composition. Source apportionment for organic aerosol (OA) suggested that primary OA in the northeastern TP was attributed to hydrocarbon OA (HOA) from anthropogenic emissions, while it was dominated by biomass burning OA (BBOA) in the southeastern TP. Regarding secondary aerosol, a marked enhancement in nitrate fraction was observed on aged BC coating in Xihai when the air masses were brought by updrafts and easterly winds from lower-altitude areas. With the development of boundary layer, the enhanced turbulent mixing promoted the elevation of anthropogenic pollutants. In contrast to Xihai, the thickly coated BC in Lulang was mainly caused by elevation and transportation of biomass burning plumes from south Asia, showing a large contribution of secondary organic aerosol (SOA). The distinct transported emissions lead to substantial variations of both chemical composition and light absorption ability of BC across the TP. The thicker coating and higher mass absorption cross-section (MAC) of PMBC in air masses elevated from lower-altitude regions reveal the promoted BC aging processes and their impacts on the mixing state and light absorption of BC in the TP. These findings emphasize the vulnerability of plateau regions to influences of elevated emissions, leading to significant changes in BC concentration, mixing states and light absorption across the TP, all of which need to be considered in the evaluation of BC radiative effects for the TP region.

Estimating the dynamics and driving factors of gross primary productivity over the Chinese Loess Plateau by the modified vegetation photosynthesis model

Gross primary productivity (GPP) is a key parameter in research on the global carbon cycle and changes. Understanding the spatiotemporal dynamics and influencing factors of GPP on the Loess Plateau (LP) helps identify the health status of ecosystems, thereby enabling the implementation of effective conservation and restoration measures. In this study, we used a modified vegetation photosynthesis model (VPM) to simulate a long-term series of GPP in the LP from 2001 to 2022, and the impacts of different land-use patterns and meteorological factors on GPP were investigated using a transition matrix, linear regression, and partial correlation analyses. The findings suggested that the modified simulation yielded a more reliable performance (coefficient of determination (R2) = 0.89, root mean square error (RMSE) = 143.47 gC·m−2·yr−1) and was suitable for further research endeavors. (1) The GPP on the LP significantly increased by 232.65 TgC from 2001 to 2022. The southeastern region contributed more than the northwestern region, and the GPP exhibited higher multi-year averages and growth rates below 1000 m elevation. (2) Forests in the southeastern region of the LP, characterized by a heightened growth rate, will influence future spatial variations in GPP increases across the LP. Despite the decline in grassland and cultivated land areas, substantial land coverage has significantly contributed to the overall GPP growth. Urbanization encroaching on cultivated land has emerged as a key contributor to the decline in GPP in low-altitude regions. (3) Air temperature was the main physical driving force for GPP change in the LP. Additionally, the GPP in forested regions exhibited a negative correlation with rainfall, whereas the GPP in areas undergoing the return of cropland to forest–grassland and cropland reclamation correlated negatively with solar radiation. (4) The attribution analysis indicated that the surge in vegetation GPP on the LP was collectively driven by human activities and meteorological changes, with human activities dominating these changes by 61.41 %. This study deepens the understanding of terrestrial ecology in semi-humid regions and provides scientific insights for implementing ecological governance strategies in the LP.

Geographic distribution and impacts of climate change on the suitable habitats of two alpine Rhododendron in Southwest China

Mountains of Southwest China (MSC) serve as a prominent geographical distribution center for Rhododendron delavayi and Rhododendron irroratum (Ericaceae). These mountains are currently experiencing an unparalleled warming trend, which poses severe challenges to the survival of these keystone alpine Rhododendron species. However, the geographical distribution responses of these species to climate change remain incompletely understood and are often overlooked. Here, we constructed ensemble models (EMs) using ten models of five algorithms to calibrate ecological niche models and predict suitable habitat areas for the two Rhododendron species across four climate emission scenarios over three distinct periods. Our analysis indicated the higher importance of elevation than temperature and precipitation in shaping the spatial distribution of the two alpine Rhododendron species. The current suitable habitats of R. delavayi and R. irroratum have areas spanning 14.85 × 104 and 11.01 × 104 km2, respectively, which are mostly distributed in the western and central regions of MSC. The suitable habitat of R. delavayi is projected to decrease by 15.09–75.31 %, but the potential habitat of R. irroratum is expected to shrink by12.71 % to 76.8 % in different future climate scenarios. The suitable habitats of these species may become confined in a “summit trap” within relatively low-altitude regions, whereas habitats distributed at high altitudes may serve as “biological refuges.” The future distribution of the two alpine Rhododendron species will shift to high altitudes in westward and northward regions, with substantial thermal and hydrothermal changes as the primary drivers of habitat alteration and migration patterns. The losses or benefits for species under climate warming depend on their ecological niches and geographical location, which provide a geographical guidance for the long-term conservation and sustainable use of species and essential insights into the spatial conservation assessment of alpine plant groups in biodiversity hotspots in the future.

Relationship between Urban Forest Fragmentation and Urban Shrinkage in China Differentiated by Moisture and Altitude

Forest fragmentation and urban shrinkage have become the focus of attention in global ecological conservation, with the goal of achieving sustainable development. However, few studies have been concerned with urban forest patterns in shrinking cities. It is necessary to explore whether the loss of the population will mitigate urban forest degradation. Thus, in this study, 195 shrinking cities were identified based on demographic datasets to characterize the spatiotemporal patterns of urban forests in China against a depopulation background. To illustrate the explicit spatial evolution of urban forests in shrinking cities in China, in this study, we reclassified land-use products and determined the annual spatial variations from 2000 to 2022 using area-weighted centroids and landscape pattern indexes. The effects of different climatic and topographical conditions on the spatiotemporal variations in the urban forest patterns against population shrinkage were discussed. The results demonstrated that the forest coverage rate in the shrinking cities of China increased from 40.05 to 40.47% with a generally southwestern orientation, and the most frequent decrease appeared from 2010 to 2015. Except for the temperate humid and sub-humid Northeast China, with plains and hills, all geographical sub-regions of the shrinking cities exhibited growing urban forests. Relatively stable movement direction dynamics and dramatic area changes in climatic sub-regions with large forest coverage were observed. The urban forest centroids of shrinking cities at a lower elevation exhibited more fluctuating changes in direction. The urban forests in the shrinking cities of China were slightly fragmented, and this weakened condition was identified via the decelerating fragmentation. The urban forests of the shrinking cities in the warm-temperate, humid, and sub-humid North China and basin regions exhibited the most pattern variations. Therefore, it is emphasized that the monitoring of policy implementation is essential due to the time lag of national policies in shrinking cities, especially within humid and low-altitude regions. This research concludes that the mitigation of urban deforestation in the shrinking cities of China is greatly varied according to moisture and altitude and sheds light on the effects of the population density from a new perspective, providing support for urban forest management and improvements in the quality of residents’ lives.

Relationship between serum iron, zinc, calcium, and HIF-1a-comparative analysis of 2 regions and 4 ethnic groups in China.

Altitude illness has serious effects on individuals who are not adequately acclimatized to high-altitude areas and may even lead to death. However, the individualized mechanisms of onset and preventive measures are not fully elucidated at present, especially the relationship between altitude illness and elements, which requires further in-depth research. Fresh serum samples were collected from individuals who underwent health examinations at the two hospitals in Xining and Sanya between November 2021 and December 2021. The blood zinc (Zn), iron (Fe), and calcium (Ca) concentrations, as well as hypoxia-inducible factor 1-alpha (HIF-1α) concentrations, were measured. This study conducted effective sample size estimation, repeated experiments, and used GraphPad Prism 9.0 and IBM SPSS version 19.0 software for comparative analysis of differences in the expression of elements and HIF-1α among different ethnic groups, altitudes, and concentration groups. Linear regression and multiple linear regression were employed to explore the relationships among elements and their correlation with HIF-1α. This study included a total of 400 participants. The results from the repeated measurements indicated that the consistency of the laboratory test results was satisfactory. In terms of altitude differences, except for Fe (p = 0.767), which did not show significant variance between low and high altitude regions, Zn, Ca, and HIF-1α elements all exhibited notable differences between these areas (p < 0.0001, p = 0.004, and p < 0.0001). When grouping by the concentrations of elements and HIF-1α, the results revealed significant variations in the distribution of zinc among different levels of iron and HIF-1α (p < 0.05). The outcomes of the linear regression analysis demonstrated that calcium and zinc, iron and HIF-1α, calcium and HIF-1α, and zinc and HIF-1α displayed substantial overall explanatory power across different subgroups (p < 0.05). Finally, the results of the multiple linear regression analysis indicated that within the high-altitude population, the Li ethnic group in Sanya, and the Han ethnic group in Sanya, the multiple linear regression model with HIF-1αas the dependent variable and elements as the independent variables exhibited noteworthy overall explanatory power (p < 0.05). The levels of typical elements and HIF-1α in the blood differ among various altitudes and ethnic groups, and these distinctions may be linked to the occurrence and progression of high-altitude illness.

Effect of cold arid high-altitude environment on bioactive phytochemical compounds of organically grown Brassicaceae vegetables for nutri-health security in mountainous regions

High-altitude (HA) environment presents immense physiological adversities for humans that have been overcome by supplementing bio-active phytochemicals from functional foods that support and accelerate acclimatization under these extreme environmental conditions. Several agricultural interventions have been investigated to enhance the phytochemical content in vegetables however; these studies have been limited to low-altitude (LA) regions only. In view of an existing knowledge gap, current work is designed to compare the phytochemical compositions of HA and LA-grown Brassicaceae vegetables (cabbage, cauliflower, knol-khol, and radish) using organic treatments via farm yard manure (FYM) and Azotobacter. The open field study was conducted as a two-factorial randomized block design. The first factor was treatment (T1-FYM, T2-Azotobacter, T3-FYM + Azotobacter, and T4-control) while the second was locations (HA and LA). Among all these treatments, the application of treatment T3 in HA-grown cabbage showed the highest total phenolic content (TPC; 9.56 μg/mg), total flavonoids content (TFC; 14.48 μg/mg), and antioxidant potential using 2,2-diphenyl-1-picrylhydrazyl (DPPH; 85.97%) and ferric reducing antioxidant power (FRAP; 30.77 μg/mg) compared to LA grown samples. Reverse Phase high performance liquid chromatography (RP-HPLC) analysis showed that treatment T3 at HA led to significantly high kaempferol (0.92 μg/mg) and sulforaphane (8.94 μg/mg) contents in cabbage whereas, indole-3-carbinol (1.31 μg/mg) was higher in HA grown cauliflower. The present study provides scientific evidence for the enrichment of health-promoting phytochemical compounds in Brassicaceae vegetables grown with T3 treatment specifically at HA.

Asociación entre el empleo informal y los casos positivos de COVID-19 en el Perú

Objectives: To identify the association between the number of informal employees and the number of positive COVID-19 cases in Peru. Methods: Data from the Peruvian National Institute of Statistics and Informatics and the National COVID-19 database were used. Bivariate linear regression and multivariate logistic regression were performed to evaluate the number of informal employees, population density, and altitude in relation to the number of COVID-19 positive cases. Results: Bivariate analysis showed that the number of informal employees was significantly associated with the number of COVID-19 positive cases in both high and low altitude regions (p&lt;0.001). In the multivariate analysis, it was found that the number of informal employees (p&lt;0.001), population density (p=0.02), and altitude (p&lt;0.001) were associated with the number of COVID-19 positive cases. Conclusions: Informal employees are common in low- and middle-income countries where there is no social security and they are economically dependent on daily wages. Their situation worsened due to social mobility restrictions, forcing them to continue working and, consequently, becoming quickly infected, further contributing as a contagion focus.

Phenotypic Characterization and Yield Screening of Quinoa Germplasms in Diverse Low-Altitude Regions: A Preliminary Study

In this study, 300 quinoa accessions were systematically screened for adaptation to low-altitude areas using seventeen traits. The experiment was conducted in Taigu District, Jinzhong City, Shanxi Province, in 2021, at an altitude of 791 m. Out of the 300 genotypes, 107 were able to produce flowers and fruit, with yields ranging from 538 to 5132 kg ha−1 and with 1000-grain weights between 1.19 g and 2.37 g. These 107 quinoa genotypes were categorized into four groups based on grain yield: below 1500, 1500–2250, 2250–3000, and above 3000 kg ha−1. These groups consisted of 33, 33, 24, and 17 genotypes, respectively. This study found that the 1000-grain weight ranged from 1.19 g to 2.37 g, with an average of 1.72 g, 1.72 g, 1.83 g, and 1.92 g for the respective yield levels. Among the 107 genotypes, 25 had a 1000-grain weight exceeding 2 g, and 13 of these genotypes also had yields exceeding 2250 kg ha−1. The growth period of quinoa genotypes in the low-altitude area was approximately 138–142 days, with longer growth periods associated with higher yield levels. JQ-00084 is the only genotype with a yield &gt; 3000 kg ha−1 and meets all the growth criteria, including a 1000-grain weight exceeding 2 g and a flowering-to-maturity period of over 80 days. Meanwhile, JQ-00315, JQ-00521, JQ-1029, and JQ-02405 fulfilled at least four criteria. These results highlight the importance of germplasm screening for low altitudes, and a large set of germplasms could be screened using the above criteria of phenology, growth, and yield traits.

Male yaks adapt to heat stress with enhancement of immunomodulation, anti-oxidation, and blood oxygen delivery

Yaks adapt to extremely low temperatures, but they are more susceptible to heat stress (HS). The adaptive mechanisms with crucial plasma protein markers regulating the response to HS remain elusive. In this study, data-independent acquisition proteomics were used to evaluate the thermal adaptability under chronic HS and thermal-neutral conditions. As a result, yaks increased body temperatures and respiratory rates in response to HS. Eight differential proteins mainly related to vasodilatation were decreased by HS, but another four proteins associated with blood oxygen delivery were presented at higher levels. Complement and coagulation cascades pathway was activated by HS, and more proteins were upregulated to protect against inflammation and oxidative stress by higher levels of antioxidant proteins. It is likely that yaks react to HS with enhancement of immunomodulation, anti-oxidation, and blood oxygen delivery, which is conducive to taking appropriate environment and nutrition management strategies to get healthy and high-performing yaks in low-altitude regions during summer.

Pangenome and multi-tissue gene atlas provide new insights into the domestication and highland adaptation of yaks

BackgroundThe genetic diversity of yak, a key domestic animal on the Qinghai-Tibetan Plateau (QTP), is a vital resource for domestication and breeding efforts. This study presents the first yak pangenome obtained through the de novo assembly of 16 yak genomes.ResultsWe discovered 290 Mb of nonreference sequences and 504 new genes. Our pangenome-wide presence and absence variation (PAV) analysis revealed 5,120 PAV-related genes, highlighting a wide range of variety-specific genes and genes with varying frequencies across yak populations. Principal component analysis (PCA) based on binary gene PAV data classified yaks into three new groups: wild, domestic, and Jinchuan. Moreover, we proposed a ‘two-haplotype genomic hybridization model’ for understanding the hybridization patterns among breeds by integrating gene frequency, heterozygosity, and gene PAV data. A gene PAV-GWAS identified a novel gene (BosGru3G009179) that may be associated with the multirib trait in Jinchuan yaks. Furthermore, an integrated transcriptome and pangenome analysis highlighted the significant differences in the expression of core genes and the mutational burden of differentially expressed genes between yaks from high and low altitudes. Transcriptome analysis across multiple species revealed that yaks have the most unique differentially expressed mRNAs and lncRNAs (between high- and low-altitude regions), especially in the heart and lungs, when comparing high- and low-altitude adaptations.ConclusionsThe yak pangenome offers a comprehensive resource and new insights for functional genomic studies, supporting future biological research and breeding strategies.

Myopia prevalence and ocular biometry in children and adolescents at different altitudes: a cross-sectional study in Chongqing and Tibet, China

ObjectiveTo investigate the differences in myopia prevalence and ocular biometry in children and adolescents in Chongqing and Tibet, China.DesignCross-sectional study.SettingThe study included children and adolescents aged 6–18 years in Chongqing,...

CO2 enrichment accelerates alpine plant growth via increasing water-use efficiency

Phenological changes in global vegetation are often attributed to climate warming. However, climate warming and elevated atmospheric CO2 concentration (eCO2) are two co-occurring global change factors, and how eCO2 would affect vegetation phenology has received less attention. The partial pressure of atmospheric CO2 on the Tibetan Plateau (TP) is lower than that in regions of lower altitudes. Consequently, the growth and phenology of alpine plants in this region could be more sensitive to eCO2, but this hypothesis is not yet supported by empirical evidence. Here we explored the effect of eCO2 on plant phenology (including phenophases of green-up, budding, and flowering) through a 5-year field manipulation experiment in a high-altitude (4600 m above sea level) alpine grassland on the TP. Our results showed that eCO2 significantly advanced the spring phenology of an early-flowering species (Kobresia pygmaea), while it had no impact on the phenology of two mid-flowering species (Potentilla saundersiana and Potentilla cuneata). Compared to other low-altitude regions, plant phenology on the TP underwent greater alterations under eCO2, which supports our hypothesis that the growth of high-altitude plants is more sensitive to eCO2. Furthermore, we found that eCO2 significantly reduced the overlapping of flowering between contrasting plant species, mainly due to the phenological advancement of the K. pygmaea induced by eCO2. The observed advancement of the spring phenology in K. pygmaea under eCO2 was associated with increasing ecosystem water-use efficiency (WUE), thereby advancing its subsequent phenological development, such as budding and flowering. Our findings provide experimental evidence that atmospheric CO2 enrichment can accelerate plant growth processes in high-altitude regions, and suggest that large-scale model simulations should consider the effects of elevated atmospheric CO2 concentration on plant growth and phenology.

Cardioprotective effects of high-altitude adaptation in cardiac surgical patients: a retrospective cohort study with propensity score matching.

The cardioprotective effect of remote ischemia preconditioning in clinical studies is inconsistent with experimental results. Adaptation to high-altitude hypoxia has been reported to be cardioprotective in animal experiments. However, the clinical significance of the cardioprotective effect of high-altitude adaptation has not been demonstrated. A retrospective cohort study with propensity score matching was designed to compare the outcomes of cardiac surgery between highlanders and lowlanders in a tertiary teaching hospital. The data of adult cardiac surgical patients from January 2013 to December 2022, were collected for analysis. Patients with cardiopulmonary bypass and cardioplegia were divided into a low-altitude group (<1,500 m) and a high-altitude group (≥1,500 m) based on the altitude of their place of residence. Of 3,020 patients, the majority (87.5%) permanently lived in low-altitude regions [495 (435, 688) m], and there were 379 patients (12.5%) in the high-altitude group [2,552 (1,862, 3,478) m]. The 377 highlander patients were matched with lowlander patients at a ratio of 1:1. The high-altitude group exhibited a 44.5% reduction in the incidence of major adverse cardiovascular events (MACEs) compared with the low-altitude group (6.6% vs. 11.9%, P = 0.017). The patients in the moderate high-altitude subgroup (2,500-3,500 m) had the lowest incidence (5.6%) of MACEs among the subgroups. The level of creatinine kinase muscle-brain isoenzymes on the first postoperative morning was lower in the high-altitude group than in the low-altitude group (66.5 [47.9, 89.0] U/L vs. 69.5 [49.3, 96.8] U/L, P = 0.003). High-altitude adaptation exhibits clinically significant cardioprotection in cardiac surgical patients.

Seeding alpine grasses in low altitude region increases global warming potential during early seedling growth

Introduction of alpine grasses to low altitude regions has long been a crucial strategy for enriching germplasm diversity, cultivating and acclimating high-quality species, enhancing ecosystem resilience and adaptability, as well as facilitating ecosystem restoration. However, there is an urgent need to investigate the impacts of planting Gramineae seeds on greenhouse gas (GHG) emissions, particularly during the critical stage of early plant growth. In this study, four species of grass seeds (Stipa breviflora, Poa pratensis, Achnatherum splendens, Elymus nutans) were collected from 19 high-altitude regions surrounding the Qinghai-Tibet Plateau and sown at low-altitude. Measurements of GHG emissions at early seedling growth in the mesocosm experiment using static chamber method showed a strong increase in the cumulative emissions of CO2 (5.71%–9.19%) and N2O (11.36%–13.64%) (p < 0.05), as well as an elevated CH4 uptake (2.75%–5.50%) in sites where the four grass species were introduced, compared to bare soil. Consequently, there was a substantial rise in global warming potential (13.87%–16.33%) (p < 0.05) at grass-introduced sites. Redundancy analysis showed that seed traits, plant biomass, and seedling emergence percentage were the main driving biotic factors of three GHGs fluxes. Our study unveils the potential risk of escalating GHG emissions induced by introducing high altitude grasses to low altitude bare soil, elucidating the mechanism through linking seed traits with seedling establishment and environmental feedback. Furthermore, this offers a new perspective for assessing the impact of grass introduction on ecological environment of introduced site.