Search Results (32)

The Qinghai–Xizang Plateau and its surrounding regions have experienced intense tectonic activity, resulting in complex geostress environments that cause frequent and distinctive rockburst disasters in plateau tunnel engineering. In this study, numerical simulations were conducted to investigate the distribution characteristics and patterns of tunnel rockbursts in high-altitude regions, using geostress orientation, lateral pressure coefficient, and tunnel depth as the primary independent variables. Secondary development of FLAC3D 7.00.126 was carried out using FISH language to enable the recording and visualization of tangential stress, the Russense rockburst criterion, and elastic strain energy. Based on this, the influence mechanisms of these key geostress parameters on the location, extent, and intensity of rockbursts within tunnel cross sections were analyzed. Results indicate that geostress orientation predominantly affects the location of rockbursts, with the surrounding rock in the direction of the minimum principal stress on the tunnel cross section being particularly prone to rockburst risks. The lateral pressure coefficient primarily influences the rockburst intensity and pit range within local stress concentration zones, with higher values leading to greater rockburst intensity. Notably, when structural stress is sufficiently large, rockbursts may occur even in tunnels with shallow burial depths. Tunnel depth determines the magnitude of geostress, mainly affecting the overall risk and potential extent of rockbursts within the cross section, with greater depths leading to higher rockburst intensities and a wider affected area. Full article

Activity patterns constitute a critical adaptive trait in large carnivores, enabling them to manage interspecific competition, enhance their foraging efficiency, and adapt to fluctuating environmental conditions. At the community level, elucidating the temporal activity allocation of sympatric large carnivores is essential for understanding species coexistence mechanisms. However, the activity patterns of most large carnivores remain inadequately explored. In this study, spanning a survey period from June 2014 to April 2024, we employed infrared camera technology to collect a total of 3312, 352, 240, and 79 independently validated photographs of snow leopards (Panthera uncia Schreber, 1775), wolves (Canis lupus Linnaeus, 1758), brown bears (Ursus arctos Linnaeus, 1758), and Eurasian lynx (Lynx lynx Linnaeus, 1758), respectively, across six distinct regions in the Sanjiangyuan Region (SR) and during different monitoring time periods. We utilized kernel density estimation and the coefficient of overlaps to assess diel activity pattern overlap and competitive intensities through pairwise comparisons among these four large carnivores. An analysis of the diel activity rhythm curves revealed that all four large carnivores predominantly exhibited nocturnal behavior, although their peak activity periods differed notably. Furthermore, the diel activity rhythm overlap between each pair of species showed moderate to high intensity throughout the year (0.5 ≤ Δ < 1), including during both the cold and warm seasons. Specifically, the diel activity rhythms of snow leopards and wolves, snow leopards and Eurasian lynx, and wolves and Eurasian lynx exhibited high levels of overlap annually and during the cold season (0.8 ≤ Δ < 1) but only moderate overlap during the warm season (0.5 ≤ Δ < 0.8). Our findings suggest that the diel activity rhythms of these four large carnivore species exhibited considerable overlap, potentially intensifying interspecific competition. This study advances our knowledge on the competitive and coexistence mechanisms of large carnivores in high-altitude mountainous ecosystems, offering critical data for their conservation and management. Full article

Background: Saxifraga umbellulata var. pectinata (Saxifragaceae) is recognized as a genuine medicinal material from the Qinghai–Tibet Plateau in China. This paper presents the chloroplast (cp) genome of S. umbellulata var. pectinata, marking the first report for this genus. The Tibetan medicinal plants documented in ‘Chinese Medicinal Plant Resources’ are associated with their chloroplast genomes and medicinal mechanisms. Objective: In order to resolve any potential ambiguity in conventional classifications, this study reconstructs the evolutionary position of S. umbellulata var. pectinata within the genus by comparing its chloroplast genetic information with that of other groupings. Methods: The chloroplast genome of S. umbellulata var. pectinata was sequenced using the Illumina NovaSeq 6000 platform. Subsequent sequence assembly, annotation, and characterization were performed using bioinformatics analysis. The NJ phylogenetic tree was constructed using MEGA 7.0 software. Results: The complete chloroplast genome of S. umbellulata var. pectinata is 146,549 bp in length, comprising four subregions: a large single-copy (LSC) region of 79,318 bp and a small single-copy (SSC) region of 16,390 bp, separated by a pair of inverted repeat (IR) regions each 25,421 bp long. This cp genome contains 131 genes, including 86 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The overall GC content is 38.1%. Phylogenetic analysis based on 20 cp genomes indicates that S. umbellulata var. pectinata is closely related to Saxifraga sinomontana and Saxifraga stolonifera. Full article

The temporal stability of alpine plant α-diversity remains poorly understood, constraining predictions of biodiversity dynamics. Here, this study examined spatiotemporal patterns in the temporal stability of plant α-diversity (species richness, Shannon, Simpson, and Pielou) across the Tibetan grasslands from 2000 to 2020. The temporal stability of plant α-diversity was more sensitive to changes in elevation compared to longitude and latitude. The greater the temporal stability of a plant species’ Shannon, the higher its rate of increase under the combined effects of climate change and human activities. The spatial average temporal stability of plant α-diversity declined by 8.83–16.40% across all the grasslands of the Qinghai-Xizang Plateau, while 39.34–43.77% of the region exhibited increasing trends under the combined effects of climate change and human activities. Climate change and human activities dominated 44.12–48.71% and 51.24–55.84% of grassland areas of the change of temporal stability of plant α-diversity, respectively. Radiation variability exerted some exclusive effects on the temporal stability of plant α-diversity. The relative change in plant α-diversity did not exhibit simple linear relationships with the relative change in its temporal stability. Therefore, climate change and human activities resulted in the spatial heterogenization of the temporal stability of plant α-diversity. While the overall temporal stability of plant α-diversity declined, some areas experienced local increases. Human activities drove changes in temporal stability across a broader area than climate change. In addition to climate warming and precipitation changes, attention should also be paid to the impact of radiation variability on the temporal stability of plant α-diversity. The relationships between plant α-diversity and its temporal stability were not always characterized by a trade-off or synergy. In future grassland biodiversity conservation efforts, it is essential to consider the potential influence of global dimming on the temporal stability of plant α-diversity. Simultaneously monitoring both α-diversity and its temporal stability, especially in areas where both are declining, should be a priority. Full article

Carbon (C), nitrogen (N), and phosphorus (P) act as pivotal regulators of biogeochemical cycles, steering organic matter decomposition and carbon sequestration in terrestrial ecosystems through the stoichiometric properties of photosynthetic organs. Deciphering their multi-scale spatiotemporal dynamics is central to unraveling plant nutrient strategies and their coupling mechanisms with global element cycling. In the current study, we modeled biogeochemical parameters (C/N/P contents, stoichiometry, and pools) in plant aboveground parts by using the growing mean temperature, total precipitation, total radiation, and maximum normalized difference vegetation index (NDVImax) across nine models (i.e., random forest model, generalized boosting regression model, multiple linear regression model, artificial neural network model, generalized linear regression model, conditional inference tree model, extreme gradient boosting model, support vector machine model, and recursive regression tree) in Xizang grasslands. The results showed that the random forest model had the highest predictive accuracy for nitrogen content, C:P, and N:P ratios under both grazing and fencing conditions (training R² ≥ 0.61, validation R² ≥ 0.95). Additionally, the random forest model had the highest predictive accuracy for C:N ratios under fencing conditions (training R² = 0.84, validation R² = 1.00), as well as for C pool and P content and pool under grazing conditions (training R² ≥ 0.62, validation R² ≥ 0.90). Therefore, the random forest algorithm based on climate data and/or the NDVImax demonstrated superior predictive performance in modeling these biogeochemical parameters. Full article

The Qinghai-Xizang Plateau is among the most ecologically vulnerable and responsive areas worldwide. Studying the characteristics of soil microbial communities along altitudinal gradients on plateaus and revealing the response mechanisms and vertical distribution patterns of microbial communities in alpine ecosystems is of significant academic value for assessing the ecological stability of the Qinghai-Xizang Plateau. This research examines the Lhasa River Basin by employing Illumina NovaSeq high-throughput sequencing to investigate how soil bacterial and fungal communities shift across elevation gradients in the Duilong Qu subbasin. This study also explored the key environmental drivers behind these microbial distribution patterns. The results indicate the following: (1) Key bacterial groups in the Duilong Qu Basin soil include Proteobacteria, Acidobacteria, and Actinobacteria, with Ascomycota, Mortierellomycota, and Basidiomycota as the prevalent fungal phyla. (2) Soil bacterial richness fluctuates with increasing elevation, and diversity exhibits a V-shaped distribution; fungal richness increases monotonically with elevation, whereas diversity shows no altitudinal dependence. (3) Principal coordinate analysis (PCoA) revealed that bacterial community structures exhibit separation trends across different elevations, with high intragroup consistency; fungal community structures at mid-elevations (4000–5000 m) show clustering similarity, whereas those at 3650–5000 m and 5500 m remain highly distinct from those at other elevations. (4) RDA reveals that factors such as accessible phosphorus, potassium, and organic content have a major effect on how bacterial communities are arranged. On the other hand, soil conductivity, along with available and total phosphorus levels, as well as pH, plays a key role in shaping fungal communities. (5) Functional prediction analysis suggests that soil bacteria shift from aerobic and biofilm-forming to facultatively anaerobic, stress-tolerant, and pathogenic traits with increasing elevation. Fungi are predominantly undefined saprotrophs, transitioning from ectomycorrhizal and pathogenic functions to saprotrophic functions at relatively high elevations. Full article

Background/Objectives: Saussurea obvallata (DC.) Edgew., Asteraceae, is a traditional medicinal herbnative to the Qinghai–Tibet Plateau (QTP). Pharmacological investigationshave validated its pharmacological effects in anti-tumor, anti-inflammatory, heat-clearing, detoxifying, and analgesia. S. obv is presently facing habitat fragmentation and population decline. Therefore, we analyzed its genetic and chemical diversity to provide a scientific basis for the conservation and sustainable use of S. obv. Methods: Seven populations of S. obv were sampled from Xizang, China. The genetic diversity was analyzed using inter-simple sequence repeat (ISSR) markers, and metabolites were identified by ultra-high-performance liquid chromatography-tandem-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS). Correlation analysis among genetic diversity, differential metabolites, and climatic factors were performed by R. Results: The genetic diversity among and within populations were both lowly and significantly correlated with geographical distance, showing a decreasing trend from east to west of the QTP. A total of 110 compounds were identified, including flavonoids, phenylpropanoids, lipids, fatty acids, terpenoids, alkaloids, etc. The metabolite contents among populations varied greatly and were related to environmental factors, mainly annual mean temperature and temperature fluctuation. The genetic diversity had little effect on the metabolic differences. Conclusions: These findings provided valuable baseline information for the conservation and pharmacological utilization of S. obv. Meanwhile, further research is necessary for the efficacy evaluation of anti-inflammatory, anti-tumor, radiation protection, and scar removal both in vitro and in vivo. Full article

To investigate the effects of freeze–thaw (FT) cycles on the mechanical properties of coarse-grained soil in southeastern Xizang under different moisture contents, this study focuses on coarse-grained soil from a large landslide deposit in Linzhi City, Xizang. FT cycle tests, triaxial shear tests, and numerical simulations were employed to systematically examine the comprehensive impact of varying FT cycles, moisture content, and confining pressure on the soil’s mechanical characteristics. The results show that FT cycles significantly affect the stress–strain behavior of coarse-grained soil in southeastern Xizang. The degree of strain softening increased from approximately 11.6% initially to 31.2% after 15 FT cycles, with shear strength decreasing by an average of 31.8%. Specifically, cohesion decreased by 38% to 55% after 0 to 15 FT cycles, and the internal friction angle decreased by approximately 29% to 32%. Additionally, higher moisture content led to more pronounced strain softening and strength degradation, while increased confining pressure effectively mitigated these deteriorative effects. Numerical simulation results indicated that as moisture content increased from 7.6% to 11.6%, the number of FT cycles required to reach the critical instability state decreased from approximately 150 to 106, and finally to only 15, with the maximum equivalent plastic strain increasing from 0.20 to 2.47. The findings of this study provide key mechanical parameters for understanding the formation and evolution of FT landslide disasters in southeastern Xizang and lay a scientific foundation for the assessment and long-term prevention of cold-region geological hazards. Full article

Fungi infestation as a disease has serious impacts on the cultivation of Morchella species. To investigate the effects of fungi infestation on the microbial diversity and community structure of soil when cultivating Morchella sextelata, we sampled soil samples of Morchella cultivars in the Qinghai–Xizang Platea and used metagenome sequencing technology to identify the disease fungi and analyze the differences in microbial diversity and structure between disease-infested and healthy soils. The disease fungi identified were Tricharina gilva and Peziza lohjaoensis, and the microbial diversity of T. gilva-infected soil was higher than that of healthy soil, while the diversity of P. lohjaoensis-infected soil was lower. Interestingly, whether infected with T. gilva or P. lohjaoensis, the soil microbial community was changed, and the dominant phyla and genera were different in different soil samples. When infected with P. lohjaoensis, the dominant phyla with relatively high abundances included Proteobacteria, Bacteroidetes, and Ascomycota, with average relative abundances of 44%, 18%, and 15%, respectively, and the dominant genera with high relative abundances encompassed Pseudomonadaceae, Terfezia, and Pedobacter, with average relative abundances of 8%, 9%, and 5%, respectively. Following infection with T. gilva, the dominant phyla with higher relative abundances were Proteobacteria, Acidobacteria, and Bacteroidetes, with average relative abundances of 46%, 15%, and 12%, respectively, and the dominant genera with high relative abundances included Hydrogenophaga, Sphingomonas, and Polaromonas, with average relative abundances of 9%, 3%, and 2%, respectively. Additionally, we found that lipid-metabolism-related genes were less abundant in the soil infected with P. lohjaoensis than in the other soil samples, and glycoside hydrolase diversity was lower in the soil infected with T. gilva than in other healthy soils. The results showed that the effects of different disease fungi on soil microbial communities and functional genes were different, which provided a theoretical basis for the sustainable cultivation of Morchella. Full article

Alpine grasslands are a critical component of the Qinghai–Tibet Plateau ecosystem, but their soil seed bank (SSB) patterns and driving mechanisms remain unclear under the influence of climate change and human activities. This study analyzed grazing exclusion (via fencing) and grazing effects using 12 sites in the alpine steppe (AS) and alpine desert steppe (AD) in northern Tibet to analyze the effects of fencing and grazing management, as well as hydrothermal and soil factors, on the SSB density and diversity. Linear regression models were applied to explore the relationships between the SSB density and environmental factors, while comparisons of the management modes revealed the potential impacts of fencing. The results show that fencing significantly increased the SSB density and diversity, especially in the AS, while grazing negatively impacted the SSB density and the Pielou evenness index. Hydrothermal factors strongly influenced the SSB in the AS, with the density positively correlated with precipitation and negatively with temperature, while responses in the AD were weak. Soil factors, such as the available phosphorus (SAP) and available potassium (SAK), were key to SSB formation in the AD, whereas ammonium nitrogen (NH4_N) and the pH were critical in the AS. Fencing optimized the hydrothermal conditions and nutrient availability, promoting SSB recovery, though its effects varied between the grassland types. This study provides scientific insights for alpine grassland restoration and sustainable management. Full article

The Qinghai–Xizang Plateau (QXP) is the highest plateau on Earth, with a significant quantity of iron resources that significantly contribute to regional economic development in Western China. However, the exploitation of these iron deposits on the QXP is confronted with dual challenges. The complex geography and weak infrastructure lead to inadequate transport accessibility, while the strict ecological regulations and stringent environmental protection policies further complicate resource development. This study focuses on the transport accessibility issues related to iron deposits on the QXP, aiming to assess the suitability for regional iron resource development. This study conducts a comprehensive, multidimensional analysis encompassing the spatial distribution of iron deposits, the characteristics of the transport network, and economic dynamics. Based on these analyses, an integrated suitability evaluation model is developed to assess the accessibility of iron deposits on the QXP. The results indicate that the transport accessibility of iron deposits on the QXP displays obvious spatial disparities. The deposits on the western QXP exhibit lower accessibility due to the remoteness from major economic centers and underdeveloped transport infrastructure. In contrast, the deposits on the eastern QXP, which are closer to transportation and economic centers, show greater development potential. Additionally, this study innovatively incorporates economic dynamics and ecological protection factors into the transport accessibility evaluation framework, revealing the coupling relationship between the transport conditions, economic patterns, and mineral resource development potential. It provides scientific evidence for the balancing of resource development and environmental protection in ecologically sensitive areas. The findings could contribute to optimizing the iron resource development strategies on the QXP and provide theoretical support for future regional infrastructure planning. Full article

The Qinghai-Xizang Plateau, known for its high altitude, geological history of plate collision, crustal uplift, and special ecology factors, provides an ideal environment for studying fungal biodiversity in extreme environmental conditions. Some species within the Conocybe, containing secondary metabolites such as psilocybin, phallotoxins, and amatoxins, have potential medicinal value for treating psychiatric disorders and for use in drug development. This study investigates Conocybe (Bolbitiaceae, Agaricales) on the Plateau, based on specimens collected over the past decade, using morphological and molecular phylogenetic analyses. Seven species were identified, including four new species: C. alticola, C. alticoprophila, C. versicolor, and C. yadongensis. Molecular analyses, utilizing multi-gene sequence data (ITS, nrLSU, and tef-1α), support the taxonomic position of these new species within this genus as new species. Detailed descriptions, illustrations, photographs, line drawings, and comparisons with related species are provided for the new taxa. This study enriches the species diversity of Conocybe on the Qinghai-Tibet Plateau, further enhancing our understanding of fungal biodiversity in this region. Full article

Amphibians serve as reliable indicators of ecosystem health and are the most threatened group of vertebrates. Studies on their spatial distribution pattern and threats are crucial to formulate conservation strategies. Gongga Mountains, with a peak at 7509 m a.s.l. and running latitudinally, are in the center of the Hengduan Mountains Range and at the eastern steep edge of the Qinghai–Xizang Plateau, providing heterogeneous habitats and varied niches for amphibians. In this study, we combined 83 days of field work with information from 3894 museum specimens that were collected over the past 80 years, and identified twenty amphibian species belonging to seven families and twelve genera by morphology. Of these species, seven were listed in the threatened categories of the Red List of China’s Biodiversity and thirteen were endemic to China. Ten species were found on the plateau side (western slope) and eleven species were found on the other side close to the Sichuan Basin (eastern slope). Only one species was found on both sides, indicating different community structures horizontally. The species richness was unimodal vertically and peaking at mid elevation on both sides, with the maximum number (ten vs. nine) of species occurring at 3300–3700 vs. 1700–1900 m a.s.l. and in different types of vegetation. The elevation span and body length of species distributed on both slopes did not show significant differences. These findings help to understand the horizontal and vertical distribution pattern of amphibian diversity, laying a foundation for future biogeographical and conservation research in this area. Full article

There is still a lack of high-precision and large-scale soil ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃⁻-N) and available phosphorus (AP) in alpine grasslands at least on the Qinghai–Xizang Plateau, which may limit our understanding of the sustainability of alpine grassland ecosystems (e.g., changes in soil NH₄⁺-N, NO₃⁻-N and AP can affect the sustainability of grassland productivity, which in turn may alter the sustainability of livestock development), given that nitrogen and phosphorus are important limiting factors in alpine regions. The construction of big data mining models is the key to solving the problem mentioned above. Therefore, observed soil NH₄⁺-N, NO₃⁻-N and AP at 0–10 cm and 10–20 cm, climate data (air temperature, precipitation and radiation) and/or normalized vegetation index (NDVI) data were used to model NH₄⁺-N, NO₃⁻-N and AP in alpine grasslands of Xizang under fencing and grazing conditions. Nine algorithms, including random forest algorithm (RFA), generalized boosted regression algorithm (GBRA), multiple linear regression algorithm (MLRA), support vector machine algorithm (SVMA), recursive regression tree algorithm (RRTA), artificial neural network algorithm (ANNA), generalized linear regression algorithm (GLMA), conditional inference tree algorithm (CITA), and eXtreme gradient boosting algorithm (eXGBA), were used. The RFA had the best performance among the nine algorithms. Climate data based on the RFA can explain 78–92% variation of NH₄⁺-N, NO₃⁻-N and AP under fencing conditions. Climate data and NDVI together can explain 83–93% variation of NH₄⁺-N, NO₃⁻-N and AP under grazing conditions based on the RFA. The absolute values of relative bias, linear slopes, R² and RMSE values between simulated soil NH₄⁺-N, NO₃⁻-N and AP based on RFA were ≤8.65%, ≥0.90, ≥0.91 and ≤3.37 mg kg⁻¹, respectively. Therefore, random forest algorithm can be used to model soil available nitrogen and phosphorus based on observed climate data and/or normalized difference vegetation index in Xizang’s grasslands. The random forest models constructed in this study can be used to obtain a long-term (e.g., 2000–2020) raster dataset of soil available nitrogen and phosphorus in alpine grasslands on the whole Qinghai–Tibet Plateau. The raster dataset can explain changes in grassland productivity from the perspective of nitrogen and phosphorus constraints across the Tibetan grasslands, which can provide an important basis for the sustainable development of grassland ecosystem itself and animal husbandry on the Tibetan Plateau. Full article

Hairgrass (Deschampsia caespitosa), a widely distributed grass species considered promising in the ecological restoration of degraded grassland in the Qinghai-Xizang Plateau, is likely to be subjected to frequent drought and waterlogging stress due to ongoing climate change, further aggravating the degradation of grassland in this region. However, whether it would acclimate to water stresses resulting from extreme climates remains unknown. Proline accumulation is a crucial metabolic response of plants to challenging environmental conditions. This study aims to investigate the changes in proline accumulation and key enzymes in hairgrass shoot and root tissues in response to distinct climate extremes including moderate drought, moderate waterlogging, and dry–wet variations over 28 days using a completely randomized block design. The proline accumulation, contribution of the glutamate and ornithine pathways, and key enzyme activities related to proline metabolism in shoot and root tissues were examined. The results showed that water stress led to proline accumulation in both shoot and root tissues of hairgrass, highlighting the importance of this osmoprotectant in mitigating the effects of environmental challenges. The differential accumulation of proline in shoots compared to roots suggests a strategic allocation of resources by the plant to cope with osmotic stress. Enzymatic activities related to proline metabolism, such as Δ¹-pyrroline-5-carboxylate synthetase, ornithine aminotransferase, Δ¹-pyrroline-5-carboxylate reductase, Δ¹-pyrroline-5-carboxylate dehydrogenase, and proline dehydrogenase, further emphasize the dynamic regulation of proline levels in hairgrass under water stress conditions. These findings support the potential for enhancing the stress resistance of hairgrass through the genetic manipulation of proline biosynthesis and catabolism pathways. Full article