Search Results (361)

Alpine shrub meadows on the Qinghai–Tibet Plateau are key warm-season pastures that support pastoral production and ecosystem stability in fragile high-elevation regions. Due to low temperatures, short growing seasons, and slow vegetation recovery, these pastures are highly sensitive to inappropriate grazing management. However, the effects of different grazing–rest time configurations on plant community composition and leaf functional traits in alpine shrub meadows remain insufficiently understood. In this study, we evaluated five grazing treatments in an alpine shrub meadow in Sunan County, central–eastern Qilian Mountains: 10 days grazing–20 days rest (T1), 15 days grazing–15 days rest (T2), 20 days grazing–10 days rest (T3), continuous grazing (CG), and grazing exclusion (CK). In the third year of treatment implementation, we measured the community diversity, species importance values, and leaf functional traits of four dominant species: Elymus nutans, Carex tibetikobresia, Oxytropis kansuensis, and Bistorta vivipara. T1 and T2 significantly increased species richness, Shannon–Wiener diversity, and Simpson diversity compared with CG and CK. NMDS and PERMANOVA further showed significant differences in overall community composition among grazing treatments. Grazing generally reduced the leaf length, leaf width, and leaf area, whereas T2 showed relatively stronger leaf recovery among grazing treatments. Specific leaf area, specific leaf weight, and leaf length–width ratio showed higher variability and calculated plasticity than leaf thickness and leaf dry matter content, suggesting that resource-acquisition and morphological traits were more responsive to grazing than conservative structural traits. The coefficient of variation of leaf traits was positively associated with the plasticity index, although this association should be interpreted cautiously because both indices were calculated from the same underlying trait dataset. Overall, under the conditions of this three-year, single-site experiment and a target moderate grazing intensity, the 15-day grazing–15-day rest regime performed best among the tested treatments. This regime may provide a practical reference for rotational grazing management in similar warm-season alpine shrub meadows, but its broader applicability requires further validation across different grassland types, grazing intensities, climatic conditions, and longer monitoring periods. Full article

To explore the distribution patterns of plant communities in southwestern Xizang and their relationships to environmental factors, this study focused on providing a theoretical basis for the conservation of biodiversity and ecological restoration of plant communities in the study area. Based on survey data from 87 sample plots in southwestern Xizang, in this study, two-way indicator species analysis (TWINSPAN) and canonical correspondence analysis (CCA) were employed for quantitative classification and ordination purposes, respectively. Additionally, the diversity of the classified community types obtained was analyzed, along with the factors influencing them. The results indicated that: a total of 295 species of vascular plants belonging to 171 genera and 61 families were recorded in the 87 sample plots; according to TWINSPAN classification, the plants in southwestern Xizang were divided into 17 associations, with the vegetation types being dominated by tussock-forming grass alpine steppes and tussock-forming Kobresia alpine meadows; CCA ordination revealed that the annual average temperature, annual precipitation, and altitude exhibited significant explanatory power; both the α- and β-diversity indices of the coniferous forest community type were the highest, indicating notable community stability; and annual average temperature and annual precipitation significantly affected plant diversity, while the altitude was negatively correlated with the above diversity indices. In summary, the temperature and precipitation were the main environmental factors influencing the composition and distribution of plant communities in southwestern Xizang. The research results could provide a theoretical basis for further investigation and conservation of plant diversity as well as ecological restoration in southwestern Xizang. Full article

The Delphinium albocoeruleum Maxim is a perennial herbaceous plant of the Ranunculaceae family, genus Delphinium. It typically grows in well-drained alpine meadows or shrublands at elevations of 2500–4000 m, which shapes the species’ unique environmental adaptation mechanism and endows it with high medicinal value. There are a few reports on the chemical constituents and biological activities of this plant. Therefore, this study focuses on the chemical constituents of the plant in order to discover structurally novel alkaloids. This paper reports on the isolation and structural characterization, using HRMS and 1D and 2D NMR, of a new alkaloid that came from the plant. Full article

Soil extracellular enzymes serve as critical drivers in the cycling of nutrients within ecosystems, and their stoichiometry can effectively reveal the metabolic resource limitations of soil microorganisms. However, extracellular enzyme activities, microbial metabolic characteristics, and their influencing factors in different grassland types in the Qilian Mountains have rarely been studied. This study focuses on alpine meadows (TJs), swampy meadows (HBs), and temperate desert grasslands (DLHs) in the Qilian Mountains. Extracellular enzyme activity and stoichiometric characteristics in the 0–30 cm soil layer were analyzed to explore the limiting factors on microbial metabolism and clarify the main driving factors affecting nutrient limitation. Compared with swampy meadows and temperate desert grasslands, alpine meadows exhibited greater extracellular enzyme activity, as revealed by the results. Statistical analysis revealed that enzyme activity exhibited a significant positive correlation with nitrate nitrogen (NO₃⁻-N), total phosphorus (TP), total potassium (TK), available potassium (AK), and dissolved organic carbon (DOC), while showing a significant negative correlation with soil moisture content (SWC) (p < 0.05). Vector analysis of soil enzymes showed that soil microorganisms in the three grassland types are limited by carbon (C) and phosphorus (P). Among them, DLH microorganisms are highly restricted by carbon, while HB microorganisms are highly restricted by phosphorus. Random forest results showed that total phosphorus (TP), available potassium (AK), nitrogen-to-phosphorus ratio (N: P), nitrate nitrogen (NO₃⁻-N), and readily oxidizable carbon (ROC) contribute significantly to vector length, while total potassium (TK), soil organic carbon (SOC), particulate organic carbon (POC), bulk density (BD), and carbon–nitrogen ratio (C: N) contribute significantly to vector angle. A partial least squares path model (PLS-PM) revealed that although microbial metabolic limitation is influenced by specific soil factors, the comprehensive effect of soil physicochemical properties is the dominant factor regulating microbial carbon and phosphorus limitation. This study provides valuable data and insights that elucidate the metabolic characteristics of soil microorganisms across different grassland types in the Qilian Mountains, thereby improving the mechanistic understanding of soil nutrient cycling and supporting evidence-based strategies for the sustainable management and conservation of these fragile ecosystems. Full article

Human disturbances, such as habitat destruction and overharvesting, are greatly harming ecosystems and causing significant declines in biodiversity. Although protected areas play a crucial role in conserving terrestrial mammals, nearly non-protected areas (N-PAs) have similar functions, harbor high biodiversity and ecosystem integrity, and deserve to be protected. To identify the conservation value of mammalian species in critical ecosystems within N-PAs, we conducted a camera-trap survey in Luolong County, Tibet, from November 2019 to June 2023, monitoring 159 sites and documenting 25 mammalian species across 28 similar or dissimilar habitats. We found this area was an integrity ecosystem with higher species richness and diversity in scrub and evergreen forests with notable occurrence of herbivores comprising musk deer, chinese serow, woolly hares and carnivores such as the common leopard, snow leopards, red foxes and stone marten. Mammalian species occurrence increased away from human activities. Different habitats and seasons influenced diversity and species interactions. Key findings include species preferences for specific habitats, such as blue sheep on southern slopes during snow, musk deer in mixed forests, and red foxes avoiding alpine meadows. Habitat type, elevation, and human disturbance significantly impacted species distribution and behavior. The study also found that snow leopard activity time negatively correlates with woolly hare, while common leopards are influenced positively by hares and negatively by brown bears. Red foxes are slightly more active near the chinese serow occurrence areas. Other predators and prey, such as eurasian lynx, gray wolves, musk deer and stone martens show specific seasonal and interspecific interactions, with some relationships explaining small portions of variation. Overall, species temporal detection events are interconnected through complex ecological interactions. These findings improve our understanding of habitat hosting for rare species and the balance of endangered prey and predator communities in N-PAs in Tibet, emphasizing their significance for conservation efforts. Full article

In plant–pre-dispersal seed predator interactions (e.g., flowerheads–flies), insect morphological differentiation is frequently driven by divergent host plants. However, wing morphological variation among flies associated with different flowerhead species has seldom been explored in natural alpine systems. In an alpine meadow of the Qinghai–Tibet Plateau, larvae of four host-associated morphological groups of Tephritis sp. cf. femoralis (1, 2, 3, 4) feed on four asteraceous species: Saussurea nigrescens (SN), Carduus nutans (CN), Leontopodium leontopodioides (LL), and Anaphalis lactea (AL). We examined the wing size and shape of these four groups using a landmark-based geometric morphometric approach. The host plants vary significantly in capitular diameter, dry weight, and depth. Within each host-associated group, female wing sizes (length, width and centroid size) were significantly larger than those of males. Wing size differed significantly among the four female and four male groups across host plants. Female ovipositor length varied in parallel with capitulum depth across the four host plants. Significant intersexual differences in wing shape were observed in SN, LL, and AL. Wing shape also varied distinctly among groups in both sexes across host plant capitula, enabling clear discrimination of host-associated groups. Linear discriminant analysis achieved high correct classification rates for both sexes, supporting clear morphological separation among host-associated groups. In conclusion, variations in wing size, wing shape and ovipositor length were associated with host traits. Overall, our study illustrates morphological differentiation correlated with host plants in flowerhead–fly pre-dispersal seed predator interactions in the alpine meadow system. Full article

To elucidate the mammalian community structure and interspecific relationships within the alpine ecosystem of the Qinghai–Tibet Plateau, this study was conducted in the Selin co National Nature Reserve for Black-necked Cranes, Tibet. Based on infrared camera monitoring data collected from June 2023 to July 2024, we analyzed mammalian species diversity and their spatial association patterns. A total of 150 infrared cameras were deployed, of which 128 were effectively retrieved, yielding 13,301 effective camera-trap days and 31,170 photographs of mammals. In total, 21 mammal species were recorded, belonging to 5 orders, 9 families, and 17 genera. The species accumulation curve approached an asymptote, indicating adequate sampling effort. Relative abundance analysis showed that Bharal (Pseudois nayaur) was the dominant species (RAI = 13.72), followed by Plateau Pika (Ochotona curzoniae) (RAI = 8.44), Moupin Pika (Ochotona thibetana) (RAI = 5.93), and Red Fox (Vulpes vulpes) (RAI = 5.50), while Snow Leopard (Panthera uncia) exhibited a moderate abundance level (RAI = 3.69). Significant differences in species diversity were observed among habitat types. Alpine meadow and meadow–desert ecotone exhibited higher diversity indices, whereas alpine desert and alpine bare rock habitats showed lower diversity. Interspecific association analysis identified 30 significant species pairs (p < 0.05), among which positive associations accounted for 93.3% and negative associations for 6.7%. The constructed association network comprised 16 nodes and 30 edges, with Chiru (Pantholops hodgsonii), Snow Leopard, and Red Fox serving as key hub species. Predator–prey pairs exhibited clear spatial coupling, while positive associations among herbivores mainly reflected shared utilization of similar habitat resources. The association structure varied across habitats, being most complex in alpine meadow, whereas no significant associations were detected in alpine desert. Overall, the mammalian community in this region is characterized by “low species richness and high endemism,” with interspecific relationships dominated by positive associations. Habitat heterogeneity plays a critical role in shaping the structure of the association network. These findings provide a scientific basis for biodiversity conservation and alpine ecosystem management on the Qinghai–Tibet Plateau. Full article

In this study a new species of Pedicularis, P. dieshanensis, is described. It is endemic to the Die Mountains, China, and grows on the alpine meadow at the edge of the fir forest at elevations of 3150–3500 m. This species is characterized by the presence of cauline leaves in trimerous or tetramerous whorls, a pinnatifid leaf margin, purple corolla, galea with a conical beak, slightly tilted to the left, and hairless filaments. The new species morphologically resembles P. cheilanthifolia and P. anas, with its leaves in trimerous or tetramerous whorls, the beaked and toothless corolla galea, bases of petioles of leaves and bracts that are not connate or cupular, flowers more than 10 mm in diameter, and a corolla tube decurved in the calyx tube. But the new species differs from P. cheilanthifolia by having a pinnatifid leaf margin, shorter galea, longer beak and hairless filaments, and it differs from P. anas by having a pinnatifid leaf margin, stable flower color and longer beak. In this paper, a detailed description of the new species including data on its habitat, ecology, phenology, and conservation status; a distribution map; a detailed illustration; field photographs; and a comparison with closely related species is provided. Full article

Satellite remote sensing-based soil moisture (SM) retrieval quantifies the spatial and temporal distributions of SM to support Earth system modeling. However, existing SM products, including satellite remote sensing, model-simulated, and land data assimilation products, are plagued by large measurement errors. The Triple Collocation (TC) method can systematically quantify these errors and generate spatially and temporally continuous SM. In this study, we analyzed SM over the Qinghai-Tibetan Plateau (QTP) using three mainstream products: The European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-interim) SM, the National Centers for Environmental Prediction Climate Forecast System version 2 (CFSv2) SM, and the China Meteorological Administration Land Data Assimilation System Version 1.0 (CLDAS-V1.0) SM. Results show that the ERA-interim contributes the largest weight to the TC-blended SM over the QTP, followed by CFSv2, while CLDAS-V1.0 makes the minimum contribution. The three products yield consistent results in the eastern and southern QTP but show significant discrepancies in the northwestern region. The TC-blended SM performs well across most land cover categories in the QTP, except Alpine swamp meadow areas. Our findings confirm that this SM blending technique effectively improves the accuracy of existing SM products, with wide application potential in future research. Full article

Although bud banks are key components of vegetation regeneration in degraded alpine meadows, their relationships with soil conditions on the Qinghai–Tibet Plateau remain insufficiently understood. In this study, we investigated bud bank composition and density, plant functional group biomass, soil physicochemical properties, and soil microbial biomass across five degradation stages of alpine meadows in a long-term controlled grazing experiment. Field sampling was conducted in mid-August 2021, and the relationships between bud bank densities, plant biomass, and soil variables were evaluated using comparative statistical analyses, redundancy analysis, and structural equation modeling. Bud bank density increased from non-degraded to moderately degraded meadows, reaching 3075 buds m⁻², but declined sharply in severely degraded meadows to 183 buds m⁻². Regarding distinct bud types, rhizome and tiller bud densities peaked in moderately degraded alpine meadows (1217 and 1750 buds m⁻², respectively), whereas dicot bud density peaked in lightly degraded meadows. Bud bank density was positively associated with higher soil moisture content and negatively associated with increased soil bulk density. Moreover, bud bank density was positively correlated with soil organic carbon, total phosphorus, ammonium nitrogen, and soil microbial biomass carbon, nitrogen, and phosphorus. Our findings indicate that soil conditions may favor the maintenance of high bud bank density in moderately degraded meadows with high soil moisture, low bulk density, and more nutrient-rich soil conditions in moderately degraded meadows. Overall, our results indicate that alpine meadow degradation influences belowground regenerative capacity through changes in soil conditions and associated shifts in bud bank dynamics. Therefore, assessments and restoration of degraded alpine meadows should consider bud bank persistence in addition to aboveground vegetation characteristics. Full article

Although grazing is a key driver of nitrogen cycling in alpine meadow soils, a systematic understanding of how different grazing intensities shape the structure and functional potential of soil nitrogen-cycling microbial communities remains lacking. In this study, soil samples were collected under five grazing intensities (no grazing, light grazing, moderate grazing, heavy grazing, and extreme grazing) and metagenomic sequencing was employed to analyze variations in nitrogen-cycling microbial communities and functional genes. The results showed that bacteria were the dominant group in nitrogen-cycling communities (relative abundance: 93.99–98.98%), with significant community differentiation across grazing intensities. Light grazing maintained relatively high microbial diversity, whereas moderate and heavy grazing led to more pronounced differences in community composition. Functional gene analysis identified 41 nitrogen-cycling-related genes, primarily involved in denitrification, nitrate reduction, and ammonia assimilation. Light grazing enhanced nitrate reduction and glutamate synthesis; moderate grazing exhibited the strongest ammonia assimilation potential; heavy grazing significantly increased denitrification activity, indicating an elevated risk of nitrogen loss; and under extreme grazing, both the number and abundance of nitrogen-cycling functional genes declined markedly, with functional composition becoming simplified. Collectively, light grazing is more conducive to maintaining the balance between soil microbial diversity and nitrogen-cycling function in alpine meadows, whereas overgrazing disrupts the equilibrium between microbial communities and nitrogen metabolism. This study provides a microbiological basis for the restoration of degraded alpine meadows and sustainable grazing management. Full article

The Source Region of the Yangtze River is a high-altitude area with extensive permafrost on the Tibetan Plateau. While temperature, precipitation, and radiation significantly affect vegetation phenology, the influence of permafrost changes remains unclear. Using the daily Long-term Seamless NOAA AVHRR NDVI Dataset of China (2003–2022), we extracted the start (SOS) and end (EOS) of the growing season in the Source Region of the Yangtze River (SRYR). Soil thawing date (SOT) was obtained from freeze–thaw state products, while active layer thickness (ALT) was estimated using the Stefan model based on MODIS land surface temperature (LST). Partial least squares regression and mediation analysis quantified the direct and indirect effects of permafrost degradation. Results show: (1) The end of the growing season (EOS) became significantly earlier in 64.33% of the region, while the start of the growing season (SOS) showed little change. (2) The effect of SOT on SOS depends on moisture conditions. Earlier SOT leads to earlier SOS in wetter areas by supplying meltwater, but delays SOS in cold–dry areas by increasing soil water loss. (3) Thicker ALT strongly promotes earlier EOS, accounting for up to 42.61% of EOS variation in cold–dry zones, because a deeper active layer potentially promotes downward movement of water, which may further lead to the potential leaching of nutrients from the shallow root zone, limiting resources for shallow-rooted plants. (4) Alpine meadows respond more strongly to permafrost changes than alpine grasslands. Overall, water loss caused by permafrost degradation may reduce the potential lengthening of the growing season under climate warming, highlighting the key role of soil water in linking permafrost and vegetation dynamics. Full article

The tanning hormone (Bursicon) is a heterodimer secreted by the insect nervous system, playing a crucial role in the process of cuticle darkening and hardening and wing expansion in insects. In this study, we knocked out the GqBurs gene using RNAi, thereby impairing the flight ability of adult males by affecting wing development, laying the groundwork for further control of the damage they cause to alpine meadows. The GqBurs gene was successfully characterized and expressed at all developmental stages of Gynaephora qinghaiensis, with higher expression in 5th instar larvae and wing primordia. In order to investigate the potential role of the Burs gene in wing development, we used RNAi technology to inhibit the expression of the GqBurs gene by in vivo injection of dsGqBurs into male adults of G. qinghaiensis, with the aim of affecting their flight ability. The silencing efficiency of the GqBurs gene was 86.12%, 97.27%, 65.61%, and 30.51% in each tissue (thorax, abdomen, wing, and wing base) 12 h after dsGqBurs injection. In addition, 12 h after injection of exogenous hormones (20E, JH, and Insulin) and a PKA inhibitor (H-89), we found that the GqBurs gene was affected by 20E, H-89, JH, and Insulin, and its overexpression and gene silencing were observed in the thorax, abdomen, wings, and wing primordia of male adults of G. qinghaiensis. These results indicate that the GqBurs gene plays a crucial role in the wing development of male adults of G. qinghaiensis. Furthermore, a decrease in GqBurs gene expression further affects the extension and expansion of the wings, thereby impacting the insect’s flight ability. Full article

Particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) are two operationally defined fractions frequently used in studies related to soil organic carbon (SOC) dynamics. However, the changes and governing mechanisms of these fractions, particularly along a restoration chronosequence, remain poorly understood. Here, we investigated changes in SOC fractions, soil properties, and microbial communities across a restoration chronosequence (1, 5, 7, 13, and 20 years) of alpine meadows using a space-for-time substitution approach on the Qinghai–Tibet Plateau. We quantified the contributions of biotic and abiotic drivers using Spearman correlation analysis, linear regression and random forest analysis. The results revealed a unimodal pattern in SOC, POC, and MAOC contents, peaking at 7, 5, and 7 years, respectively, with no further increase thereafter. Restoration duration strongly shaped microbial community structure and observed species richness, but had no significant effect on Shannon index and Pielou index. Random forest analysis identified soil water content (SWC) and total nitrogen (TN) as the primary predictors of SOC. The microbial community composition dominated the variation in POC while enzyme activity was the key driver of MAOC. Our findings highlight that soil carbon accumulation during alpine meadow restoration is a nonlinear process with a temporal threshold, and POC and MAOC are regulated by distinct biotic and abiotic mechanisms. This study provides a theoretical basis for understanding carbon sequestration mechanisms during alpine meadow restoration and developing sustainable grassland management strategies. Full article

Alpine wetlands in the Qinghai Lake Basin, located on the northeastern Qinghai–Tibetan Plateau, are ecologically important but highly vulnerable to climate change and anthropogenic disturbance. Traditional field-based surveys are labor-intensive and spatially constrained, underscoring the need for automated remote sensing approaches for large-scale wetland mapping. In this study, an object-based image analysis (OBIA) framework was developed by integrating Sentinel-2 optical imagery with Sentinel-1 synthetic aperture radar (SAR) data to classify two representative plateau wetland types: marsh meadows and inland tidal flats. Seven categories of features were evaluated, including spectral features, vegetation indices, water indices, red-edge features, topographic variables, radar backscatter, and geometric-textural metrics. The Separability and Thresholds (SEaTH) algorithm was employed for feature selection and optimization prior to classification using a Random Forest model. The results indicate that the incorporating geometric and textural features significantly improved classification performance, achieving an overall accuracy (OA) of 82.53% and a Kappa coefficient of 0.74. Moreover, the SEaTH-based feature optimization scheme yielded the best performance, with an OA of 86.24% and a Kappa coefficient of 0.79. Compared with the full feature set, this approach improved producer’s accuracy by 3.96–6.11% and increased overall accuracy by 1.48%. The proposed framework provides an effective and computationally efficient approach for mapping ecologically fragile alpine wetlands and offers valuable support for wetland conservation in the Qinghai Lake Basin. Full article