Search Results (1,004)

The functional relationship between soil permittivity and soil water content serves as the theoretical foundation for electromagnetic wave-based techniques used to determine soil moisture levels. However, the response of permittivity to changes in soil water content varies significantly across different soil types. Current models that utilize soil permittivity to estimate soil water content are often based on empirical statistical relationships specific to particular soil types. Moreover, existing physical models are hindered by an excessive number of parameters, which can be difficult to measure or calculate. This study introduces a universal model, termed the Soil Refractive Index (SRI) model, to describe the relationship between soil permittivity and soil water content. The SRI model is derived from the propagation velocity of electromagnetic waves in various soil components and the functional relationship between electromagnetic wave velocity and relative permittivity. The SRI model expresses soil water content as a linear function of the square root of the relative permittivity for any soil type with the slope and intercept as the two undetermined parameters. The slope is primarily influenced by the relative permittivity of soil water, while the intercept is mainly affected by both the slope and the soil porosity. The applicability of the SRI model is validated through tested soil samples and comparison with previously published empirical statistical models. For dielectric lossless soil, the theoretical value of the slope is calculated to be 0.126. The intercept varies across different soil types and increases linearly with soil porosity. The SRI model provides a theoretical basis for calculating soil water content using permittivity across various soil types. Full article

The Kunlun, Arjin, and Qilian mountain ranges mark the northern edge of the Qinghai–Tibet Plateau (QTP), where rapid uplift and Quaternary glacial cycles have shaped a unique cold desert ecosystem and species distribution. Despite sampling challenges, phylogeographic studies are crucial for understanding reptile populations such as the Qinghai toad-headed agama (Phrynocephalus vlangalii), a viviparous lizard with limited dispersal and multiple subspecies in the northeastern QTP. Our fieldwork identified populations of P. vlangalii on the northern slope of the Kunlun–Arjin Mountains, similar to the controversial subspecies P. v. lidskii. We analyzed 130 individuals from the northern slope of the Kunlun–Arjin–Qilian Mountains and 253 individuals from GenBank, using three mitochondrial genes and two nuclear genes to assess intraspecific differentiation and demographic history. We found high haplotype diversity and low nucleotide diversity in P. vlangalii, with phylogenetic analyses revealing six distinct clades. Clade VI, confirmed as P. v. lidskii, and Clade IV, a new genetic lineage, were identified alongside three recognized subspecies. Genetic variation was largely attributed to clade splitting, indicating significant divergence. The Mantel test indicated that geographical and environmental factors drove population differentiation. Bayesian molecular clock analysis suggested that the most recent common ancestor of P. vlangalii lived 2.55 million years ago, influenced by the Qinghai–Tibet Movement and glacial cycles. Demographic history and ecological niche modeling (ENM) indicated no population decline during the Last Glacial Maximum, supporting the glacial maximum expansion model, with ENM predicting future habitat expansion for P. vlangalii. In addition, morphological data from 13 meristic and 15 metric characters confirmed clade differences. Our findings significantly advance our understanding of P. vlangalii diversification, population dynamics and response to geological and climatic changes in the QTP. Full article

This study aimed to isolate lactic acid bacteria (LAB) with strong antioxidant activity and potential probiotic properties from yak milk and dairy products in the Qinghai–Tibet Plateau. Initial screening of the isolates was performed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay and a hydrogen peroxide tolerance test. Subsequently, the antioxidant capacity of the isolates was assessed through five distinct assays: 2,2′-azino-bis (3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging ability, superoxide anion radical scavenging ability, hydroxyl radical scavenging ability, a DPPH scavenging assay, and a reducing activity assay. The strains with the stronger antioxidant potential were then further evaluated for their probiotic properties. Whole-genome sequencing was conducted on Lactobacillus plantarum QL01. Among 1205 isolates, 9 strains exhibited potential antioxidant capabilities. Following probiotic property evaluation, QL01 was identified as a safe candidate due to its strong growth, strong adhesion ability, and resilience to acidic, bile, and simulated gastrointestinal conditions. Genome analysis revealed that most of QL01’s genes were involved in carbohydrate metabolism. Further examination of antibiotic resistance and virulence factors confirmed its safety, meanwhile genes linked to adhesion and stress responses underscored its probiotic potential. In conclusion, QL01, a strong antioxidant strain, was successfully isolated, and its probiotic potential was confirmed through comprehensive in vitro and genomic analyses. Full article

The temperature and emissivity separation (TES) algorithm is currently adopted to retrieve the land surface temperature (LST) and emissivity (LSE) from Moderate Resolution Imaging Spectroradiometer (MODIS) images (i.e., the MOD/MYD21 product). Unfortunately, the TES algorithm often yields anomalous LSE spectra for graybodies with low spectral contrast. The MODIS TES algorithm does not effectively address this issue. To overcome this limitation, refined TES algorithms, including the optimized smoothing for temperature emissivity separation (OSTES) and the temperature and emissivity separation with nonlinear constraint (TESNC), have been proposed. Although these algorithms offer theoretical improvements, their performance has not been systematically validated using real MODIS data. This study evaluates the performance of three TES algorithms (MODIS TES, OSTES, and TESNC) in retrieving LST&E from MODIS data over six lakes on the Qinghai–Tibet Plateau, which serve as representative examples of low-spectral-contrast surfaces. Three years (2018–2020) of MODIS data from six lakes on the Qinghai–Tibet Plateau were collected to retrieve LST&E using three TES algorithms. Using the quality-controlled MODIS LST product (MOD11) as a benchmark, the TESNC algorithm achieved the highest accuracy, with bias and RMSE values of 0.18 K and 0.22 K, respectively, compared with the bias and RMSE values of 0.51 K and 0.53 K for the MODIS TES algorithm and 0.58 K and 0.60 K for the OSTES algorithm, respectively. In terms of LSE, the TESNC algorithm achieved an RMSE within 0.005 for all bands, demonstrating superior accuracy over the other algorithms. Overall, the TESNC algorithm significantly improved the accuracy of LST&E retrieval from MODIS for graybodies with low spectral contrast. This study is the first to systematically evaluate refined TES algorithms using real MODIS data over graybodies. The findings provide valuable insights for improving the MODIS LST&E product and advancing the retrieval of LST&E for low-spectral-contrast surfaces. Full article

Leaf stripe disease, caused by Pyrenophora graminea, is a seed-borne fungal disease that significantly impacts hulless barley (Hordeum vulgare var. nudum) production on the Qinghai-Tibet Plateau. This study aimed to identify genetic factors conferring resistance to the leaf stripe by analyzing an F₃ population derived from a cross between the resistant landrace Teliteqingke and the susceptible landrace Dulihuang. Genetic analysis revealed that resistance in Teliteqingke was governed by two dominant genes. Using bulked segregant analysis combined with an SNP array (BSA-SNP) and RNA-seq, we identified two candidate regions on chromosomes 3H and 7H. Further analysis focused on chromosome 3H, which revealed a candidate genomic region containing seven potential disease-resistance genes. Among these, RT-qPCR experiments demonstrated significant expression induction of HORVU.MOREX.r3.3HG0232110.1 (encoding a RING/U-box superfamily protein) and HORVU.MOREX.r3.3HG0232410.1 (encoding a bZIP transcription factor) showed significant expression induction following inoculation with P. graminea. These genes are strong candidates for the resistance mechanism against leaf stripes in Teliteqingke. These results provide a foundation for functional validation of these genes and offer valuable insights for breeding disease-resistant hulless barley. Full article

Terrestrial ecosystems are vital carbon sinks that can effectively restrain the rise in CO₂ in the atmosphere. How ecosystem carbon storage (CS) in semi-arid watershed areas with slow urbanization is affected by comprehensive factors of the environment and land use, along with its temporal and spatial changes has still not been fully explored. Notably, there is a paucity of research on the temporal and spatial changes and development trends of CS in the rapid deformation belt of slopes from the eastern margin of the Qinghai–Tibet Plateau to the Loess Plateau. Taking Bailong River Basin (BRB) as an example, this study combined GeoSOS-FLUS, the InVEST model, and localized “social–economic–nature” scenario to simulate the long-term dynamic evolution of CS. The aim was to study how topographic factors and land use change, and their interactions impact carbon sinks and gradient effects in steep-slope areas, and then find out the relationship between carbon sinks and topographic factors to explore strategies to improve regional carbon sink capacity. The results showed that the following: (1) CS in BRB increased year by year, with a total increase of 558 tons (3.19%), and showed significant spatial heterogeneity, mainly due to the conversion of woodland and arable land; (2) except for land use type, the relationship between CS and topographic gradient is inverted U-shaped, showing a complex spatial response; and (3) it is estimated that by 2050, under the arable land protection and natural development scenarios, CS will decrease by 0.07% and 0.005%, respectively, encroachment on undeveloped mountain areas, while the ecological protection scenario gives priority to protecting the carbon sinks of woodland and grassland, and CS will increase by 0.37%. This study supports the implementation of targeted ecological protection measures through topographic gradient zoning, provides a reference for policy makers in similar topographic regions to effectively manage the spatial heterogeneity of CS, and helps further strengthen global and regional climate change mitigation efforts. Full article

Understanding the hydrometeorological processes of the Yarlung Tsangpo River Basin, located on the “Third Pole” Qinghai–Tibet Plateau, is crucial for effective water resource management and climate change adaptation. This study provides a comprehensive analysis of the basin’s hydrometeorological characteristics using long-term observational data from six representative stations across the upper, middle, and lower reaches. We examined trends, periodicity, variability, and correlations of key elements—precipitation, temperature, evaporation, and discharge—employing methods such as linear regression, Mann–Kendall tests, wavelet analysis, and Kendall rank correlation coefficient tests. The results indicated that precipitation and discharge exhibited non-significant upward trends, with fluctuations across decades, while temperature showed a significant increase of 0.39 °C per decade, surpassing the national and global rates. Evaporation generally decreased with increasing precipitation; however, at Lazi Station, evaporation significantly increased due to low precipitation and rising temperatures causing decreased relative humidity. Periodic analysis revealed cycles at multiple temporal scales, particularly at 2–5 years, 10 years, and over 20 years. Correlation analysis demonstrated a strong positive relationship between precipitation and discharge, and a negative correlation between evaporation and discharge. The hydrometeorological characteristics are significantly influenced by climatic factors, especially precipitation and temperature, with the warming trend potentially affecting water’s availability and distribution. These findings offer valuable insights for water resource management and highlight the need for continuous monitoring to understand hydrological responses to climatic and anthropogenic changes in this critical region. Full article

The accurate modeling of complex freeze–thaw processes and hydrothermal dynamics within the active layer is challenging. Due to the uncertainty in hydrothermal simulation, it is necessary to thoroughly investigate the parameterization schemes in land surface models. The Noah-MP was utilized in this study to conduct 23,040 ensemble experiments based on 11 physical processes, which were aimed at improving the understanding of parameterization schemes and reducing model uncertainty. Next, the impacts of uncertainty of physical processes on land surface modeling were evaluated via Natural Selection and Tukey’s test. Finally, Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was used to identify the optimal combination of parameterization schemes for improving hydrothermal simulation. The results of Tukey’s test agreed well with those of Natural Selection for most soil layers. More importantly, Tukey’s test identified more parameterization schemes with consistent model performance for both soil temperature and moisture. Results from TOPSIS showed that the determination of optimal schemes was consistent for the simulation of soil temperature and moisture in each physical process except for frozen soil permeability (INF). Further analysis showed that scheme 2 of INF yielded better simulation results than scheme 1. The improvement of the optimal scheme combination during the frozen period was more significant than that during the thawed period. Full article

Accurately extracting long-term urban and rural settlement (URS) information is crucial for studying urbanization processes and their impacts on the ecological environment. However, existing remote sensing extraction methods often rely on independent classification strategies for each period, leading to error accumulation and increased uncertainty in long-term sequence extraction. To address this, this study proposed a data/model-constrained dynamic extraction method for URS information and validated it using the Qinghai–Tibetan Plateau at five-year intervals from 1985 to 2020. The area of URS extracted by this method had a matching degree of 97.79% with the reference, with an average overall accuracy of 93.25% and a kappa of 0.89 for the 1985–2020 confusion matrix sample. The urban and rural settlement boundary (URSB) extracted by this method were more accurate than the Global Urban Boundary (GUB) dataset, particularly in spatial completeness and boundary detail. The results provide technical support for uncovering urban development patterns and their environmental impacts. Full article

As one of the countries with the most severe extreme climate disasters in the world, it is of great significance for China to scientifically understand the characteristics of extreme precipitation. The artificial neural network near-real-time dynamic infrared rainfall rate satellite precipitation data (PDIR-Now) is a global, long-term resource with diverse spatial resolutions, rich temporal scales, and broad spatiotemporal coverage, providing an important data source for the study of extreme precipitation. But its applicability and accuracy still need to be evaluated in specific applications. Based on the observation data of 824 surface meteorological stations in China, the correlation coefficient (R), relative deviation (RB), root mean square error (RMSE), and relative root mean square error (RRMSE) of quantitative statistical indicators were used to evaluate the annual maximum daily precipitation of PDIR-Now from 2000 to 2016 in this study, in order to explore the ability of PDIR-Now satellite precipitation products to monitor extreme precipitation in Chinese mainland. The results show that from the perspective of long-term series, the annual maximum daily precipitation of PDIR-Now has a good ability to monitor extreme precipitation across the country, and the R exceeds 0.6 in 65% of the years. The RMSE of different years is generally distributed between 40 and 60 mm, and in terms of time characteristics, the error of each year is relatively stable and does not fluctuate greatly with dry precipitation or abundant years. From the perspective of spatial characteristics, the distribution of RMSE is very regional, with the RMSE in the Qinghai–Tibet Plateau and Northwest China basically in the range of 0~20 mm, the Yunnan–Guizhou Plateau, the Sichuan Basin, Northeast China, and the central part of the study area in the range of 20~50 mm, and the RMSE in a few stations in the southeast coast greater than 80 mm. The RRMSE distribution of most sites is between 0 and 0.6, and the RRMSE distribution of a few sites is between 0.6 and 1.5. Generally, higher RRMSE values and larger errors are observed in the northwest and southeast coastal regions. Overall, PDIR-Now captures the regional characteristics of extreme precipitation in the study area, but it is underestimated in the wet season in humid and semi-humid regions and overestimated in the dry season in arid and semi-arid regions. Full article

Temperate glaciers in the Kangri Karpo region of the southeastern Qinghai–Tibet Plateau (QTP) have experienced significant ablation in recent decades, increasing the risk of glacier-related hazards and impacting regional water resources. However, the spatial and temporal pattern of mass loss in these glaciers remains inadequately quantified. In this study, we used ASTER L1A stereo images to construct a high-resolution elevation time series and provide a comprehensive spatial–temporal assessment of glacier elevation change from 2000 to 2024. The results indicate that almost all glaciers have experienced rapid ablation, with an average surface elevation decrease of −18.35 ± 5.13 m, corresponding to a rate of −0.76 ± 0.21 m yr⁻¹. Glaciers in the region were divided into the northern and southern basins, with average rates of −0.79 ± 0.17 m yr⁻¹ and −0.72 ± 0.13 m yr⁻¹, respectively. A notable difference in acceleration trends between the two basins was observed, with the elevation rate increasing from −0.78 ± 0.17m yr⁻¹ to −1.04 ± 0.17 m yr⁻¹ and from −0.52 ± 0.13 m yr⁻¹ to −0.92 ± 0.13 m yr⁻¹, respectively. The seasonal cycle was identified in glacier surface elevation change, with an accumulation period from November to March followed by a prolonged ablation period. The seasonal amplitude decreased with elevation, with higher elevations exhibiting longer accumulation periods and less ablation. Correlation analysis with meteorological data indicated that higher summer temperatures and increased summer rainfall intensify elevation loss, while increased spring snowfall may reduce ablation. Our analysis highlights distinct variations in glacier elevation changes across different locations, elevations, and climatic conditions in the Kangri Karpo region, providing valuable insights into glacier responses to environmental changes on the Tibetan Plateau. Full article

This study investigates the role of sea buckthorn HD-Zip genes in response to lead stress, identifying 28 genes distributed across 10 chromosomes, which are classified into four subfamilies. Each subfamily exhibits a similar gene structure and conserved protein motifs. The HD-Zip gene family is notably enriched in stress-responsive elements. Transcriptomic analysis revealed differential expression among the 28 members of the HD-Zip gene family in sea buckthorn, varying with different Pb ion concentrations. Upregulated genes were predominantly observed at stress concentrations of 1 g/kg and 5 g/kg, while downregulated genes were more prevalent at the 0.5 g/kg stress concentration. Covariance analysis indicated that large-scale gene duplication was the primary mechanism driving the expansion of the sea buckthorn HD-Zip gene family. Additionally, analysis of three-dimensional protein structures demonstrated high conservation within the HD-Zip gene, suggesting that certain sea buckthorn HD-Zip proteins may play significant regulatory roles in physiological functions. Scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS) analysis revealed that the majority of lead ions accumulated in the roots of the seedlings, with the lead concentration affecting the number, density, and function of leaf slits. These findings enhance our understanding of the complex regulatory mechanisms governing HD-Zip genes and will contribute to the genetic improvement of sea buckthorn for breeding under lead stress conditions. Full article

The unique tourism resources of the Qinghai-Tibet Plateau have created conditions for the development of ecotourism, while the existence of attractions may also have positive and negative impacts on the surrounding environment. This study defines the radiation waves that generate ecological effects as “ecological waves”, quantifies the ecological waves of attractions by buffer zone analysis of the normalized difference vegetation index (NDVI) within 20 km of 38 4A and 5A attractions on the Qinghai-Tibet Plateau in 2020, and elaborately explores the ecological effects of attractions on the surrounding environment. By combining the principle of ripple effects, it analyzes the impact of urban attractions on urban vegetation environments. The study found that attractions on the Qinghai-Tibet Plateau have a positive ecological effect on the surrounding vegetation, the positive ecological effect of suburban attractions has a distance threshold, effectively promoting vegetation greenness within a range of 6–14 km, and the ecological effect disappears beyond 14 km. In addition, applying the ripple effect model to urban attractions and city centers (Xining and Lhasa), the results indicated that among the five urban attractions in Xining, Kumbum Monastery, Qinghai Tibetan Culture Center, and Country Farming Ecological Park (with distance restrictions of 2–20 km) have significant positive ecological effects within the built-up area, while the ecological effects of Qinghai Province Museum and Qinghai-Tibetan Plateau Safari Park are not significant. The positive ecological effects of the five urban attractions in Lhasa within the built-up area are not significant, and different attractions have different distance thresholds for ecological effects. Furthermore, this study found that attractions in Qinghai have a better ecological foundation around them than attractions in Tibet, making them more suitable for the development of ecotourism. This study has opened up a new perspective on the ecological effects of attractions and provided scientific references for the development of ecological tourism in the Qinghai-Tibet Plateau. Full article

Late embryogenesis abundant (LEA) proteins are a class of proteins associated with osmotic regulation and plant tolerance to abiotic stress. However, studies on the LEA gene family in the alpine cold-tolerant herb are still limited, and the phylogenetic evolution and biological functions of its family members remain unclear. In this study, we conducted genome-wide identification, phylogenetic evolution, and abiotic stress response analyses of LEA family genes in Notopterygium species, alpine cold-tolerant medicinal herbs in the Qinghai–Tibet Plateau and adjacent regions. The gene family identification analysis showed that 23, 20, and 20 LEA genes were identified in three Notopterygium species, N. franchetii, N. incisum, and N. forrestii, respectively. All of these genes can be classified into six LEA subfamilies: LEA_1, LEA_2, LEA_5, LEA_6, DHN (Dehydrin), and SMP (seed maturation protein). The LEA proteins in the three Notopterygium species exhibited significant variations in the number of amino acids, physical and chemical properties, subcellular localization, and secondary structure characteristics, primarily demonstrating high hydrophilicity, different stability, and specific subcellular distribution patterns. Meanwhile, we found that the members of the same LEA subfamily shared similar exon–intron structures and conserved motifs. Interestingly, the chromosome distributions of LEA genes in Notopterygium species were scattered. The results of the collinearity analysis indicate that the expansion of the LEA gene family is primarily driven by gene duplication. A Ka/Ks analysis showed that paralogous gene pairs were under negative selection in Notopterygium species. A promoter cis-acting element analysis showed that most LEA genes possessed multiple cis-elements connected to plant growth and development, stress response, and plant hormone signal transduction. An expression pattern analysis demonstrated the species-specific and tissue-specific expression of NinLEAs. Experiments on abiotic stress responses indicated that the NinLEAs play a crucial role in the response to high-temperature and drought stresses in N. franchetii leaves and roots. These results provide novel insights for further understanding the functions of the LEA gene family in the alpine cold-tolerant Notopterygium species and also offer a scientific basis for in-depth research on the abiotic stress response mechanisms and stress-resistant breeding. Full article

Dioecious plants have different needs for natural resources due to sex differences, which can lead to skewed sex ratios. Clonal growth facilitates and optimizes resources of clonal plants. So, dioecious plants show inter-sex differences in clonality. However, it is unclear how the clonality varies between female and male plants when they exhibit skewed sex ratios along an altitudinal gradient. Here, we investigated the sex ratio and clonality of Hippophae tibetana populations growing at three altitudes in the alpine meadow. We founded that (i) H. tibetana growing at different altitudes mainly consisted of II and III age classes, with a significantly male-biased sex ratio observed at a low altitude, a female-biased ratio at a middle altitude, and no significant sex-bias in the population at a high altitude. (ii) The population distribution was generally random at both low and high altitudes, while clustered at middle altitudes with an increasing scale. Meanwhile, the male and female populations at a low altitude showed a negative correlation, while the male and female at a middle altitude only showed a negative correlation at a 0–0.5 m scale, and spatial independence with increasing scales. (iii) Females of H. tibetana had a strong clonal capacity than male plants at a middle altitude, while the opposite was observed at a low altitude. The number of males of H. tibetana growing at a low altitude and with higher clonal diversity were higher than females at mid altitude. Our findings will contribute to the understanding of the sexual dimorphism exhibited by dioecious plants as well as the importance of a clonal adaptation in response to environmental change. Full article