Search Results (691)

Understanding spatiotemporal variation in soil CO₂ flux (FCO₂) along elevational gradients is essential for predicting carbon–climate feedback in alpine ecosystems. However, how temperature- and moisture-related factors jointly regulate daily-scale FCO₂ and how their contributions vary with elevation remain unclear, particularly in the Sejila Mountains (Southeastern Tibetan Plateau). We conducted continuous in situ measurements of daily-scale FCO₂, air temperature (Ta), relative humidity (RH), soil temperature (ST, 0–10 cm), and volumetric soil water content (SW) across five elevational bands (3000–4200 m) in 2024–2025. Across both years, FCO₂ showed a unimodal seasonal cycle and a robust nonmonotonic spatial pattern, with the highest efflux at 3000 and 4200 m and peak rates exceeding 5.0 µmol CO₂ m⁻² s⁻¹. Cumulative carbon loss at 4200 m (909.90 g C m⁻²) exceeded that at mid-elevation sites. Linear mixed-effects models identified Ta as the most consistent positive predictor; the ST × SW interaction was not significant, indicating that temperature and moisture effects are largely additive at the daily scale. Piecewise regression revealed nonlinear SW thresholds (θ) in the FCO₂ response, with θ varying nonmonotonically with elevation. Multiple linear regression further showed that thermal predictors (Ta, ST) explained substantially more variance than moisture predictors (RH, SW), and the relative importance of thermal drivers increased with elevation. These results challenge the common expectation of a monotonic decline in soil respiration with elevation and suggest that, when SW remains above critical thresholds, warming may amplify soil carbon losses at high elevations on the Tibetan Plateau. Full article

Despite the essential role of soil microbial communities in driving nutrient cycling within alpine meadows, their distribution patterns along elevational gradients and their responses to environmental changes remain largely unexplored. To investigate this, soil samples were collected from five elevations (3300–4500 m) in the northeastern Qinghai–Tibet Plateau to analyze bacterial community composition and diversity, as well as their associations with soil physicochemical properties and enzyme activities. The results showed significant variation in bacterial community composition and diversity across elevations. Actinomycetota, Pseudomonadota, and Acidobacteriota were the dominant phyla at all sampling sites. Community diversity, measured by the Shannon index, generally increased with elevation, peaking at 4500 m and lowest at 3300 m. Pearson correlation analysis and redundancy analysis (RDA) indicated that soil bacterial community structure was significantly correlated with both soil nutrient factors and enzyme activities. Among these variables, total potassium, available phosphorus, catalase, and urease were strongly correlated with bacterial community differentiation. In addition, PERMANOVA results showed that elevation was the primary factor driving community variation, explaining a substantial proportion of the variation in community composition at a statistically significant level. Overall, this study highlights the distribution of bacterial communities in alpine meadow soils along an elevational gradient and their environmental associations, providing foundational data for understanding microbial community responses to environmental changes in alpine ecosystems. Full article

The Tibetan Plateau (TP) experienced significant climatic transitions and tectonic uplift during the Middle Miocene. Little is known about plant diversity changes and their relationship with climatic and tectonic processes in spite of extensive reconstructions of vegetation change over this period. Based on palynological assemblages spanning ~15–12 Ma from the Lunpola Basin, we quantitatively reconstruct the evolution of plant diversity around the Middle Miocene Climatic Transition (MMCT) in the central TP. Plant taxa richness and evenness of three groups of tree, shrub and herb, and pteridophyte are estimated using Hill numbers methods. Three distinct diversity phases are identified. From ~15 to 14.2 Ma, plant richness gradually increased while evenness decreased, possibly due to the development of vertical vegetation zones driven by the uplift of the central TP. From ~14.2 to 13.8 Ma, richness dropped sharply in response to rapid climatic deterioration in the MMCT. From ~13.8 to 12 Ma, both richness and evenness increased under fluctuations, associated with paleo-lake shrinkage and expansion of lakeside wetlands caused by persistent plateau uplift and climatic aridification. Long-term changes in plant diversity within the Lunpola Basin were influenced by global climate changes, the uplift of central TP, and regional hydrological dynamics during the Middle Miocene. Our findings provide paleoecological insights into the coevolution of TP growth, climate change, hydrological process, and biodiversity of alpine ecosystem. Full article

Protected areas play a critical role in conserving biodiversity and ecosystem services, yet their effectiveness in mitigating anthropogenic pressures, particularly in fragile alpine ecosystems like the Three-River-Source region of the Qinghai Plateau—a vital water tower for Asia—requires long-term and rigorous assessment. This study evaluates the effectiveness of the Three-River-Source Nature Reserve by analyzing spatiotemporal changes in the human footprint from 2000 to 2024. Utilizing a globally consistent human footprint dataset refined with high-resolution grazing intensity data for the Qinghai Plateau, we compared human footprint dynamics inside and outside the reserve and across its three functional zones (core, buffer, experimental). To isolate the policy effect, we employed a propensity score matching (PSM) approach to control for confounding geographical and socio-economic factors. Results indicate that while human pressure increased overall, the nature reserve was partially effective. The PSM-based comparison revealed that the increase in human footprint inside the nature reserve was lower than in matched external control areas. This effect was spatially heterogeneous and positively correlated with management intensity: it was most pronounced in the core zone, moderate in the buffer zone, and negligible in the experimental zone. The conservation outcomes showed notable improvement following policy enhancements, particularly after the national park’s formal establishment. The findings confirm the value of strict internal protection and functional zoning but highlight the challenge of intensifying peripheral pressures, underscoring the need for integrated landscape-level management strategies beyond the reserve’s boundaries to ensure long-term ecological integrity. Full article

Mountain ecosystems are susceptible to climate change, and alpine treeline ecotones (ATEs) represent one of the significant responsive indicators of climate-driven environmental change. This study examines long-term spatiotemporal dynamics of the ATE across the Eastern Slopes of the Canadian Rocky Mountains (ESCR) from 1984 to 2023, with the objective of assessing whether regional climate warming has influenced ATE extent and elevation across different aspects and watersheds. Multi-decadal Landsat imagery, ERA5-Land temperature data, and topographic variables were integrated within a Google Earth Engine (GEE) framework to map ATEs using the Alpine Treeline Ecotone Index (ATEI), a probabilistic approach designed to capture transitional vegetation zones. Temporal trends were evaluated using non-parametric statistics, correlation analyses, and watershed- and aspect-based comparisons. Results indicate that the total alpine treeline ecotone (ATE) area in the ESCR was approximately 13.3% larger in 2023 than in 1984. However, the temporal evolution of ATE extent and elevation was non-monotonic, and linear trend analyses did not detect statistically significant increasing or decreasing trends over the full study period. ATE elevation and expansion exhibited pronounced spatial heterogeneity, with greater changes occurring on north- and northwest-facing slopes and within selected watersheds. In contrast, summer (July–September) temperatures increased significantly (+2.84 °C), exceeding global land-only warming rates, and vegetation greenness (NDVI) showed a strong, statistically significant positive relationship with temperature. These findings show that while climate warming has clearly increased vegetation productivity, elevational ATE dynamics remain spatially heterogeneous and temporally non-synchronous with summer temperature trends. Full article

High-altitude mine wastelands in Southwest China present formidable challenges for ecological rehabilitation due to extreme climatic stressors and multi-element contamination. Ecological restoration is closely related to soil environment. However, the mechanism by which parent material-induced heterogeneity governs spontaneous vegetation succession is still poorly understood. We established 36 plots (216 quadrats) to investigate the soil physical and chemical properties and vegetation restoration of propylite, porphyry and siltstone in the Xifanping Copper Mine, Sichuan Province. Furthermore, fifteen metal/metalloid elements (Au, Ag, Mo, W, Cu, Pb, Zn, Hg, As, U, Se, Cr, Sn, Ti, Total Fe₂O₃), soil pollution and vegetation structure were evaluated. The study area exhibited severe composite pollution (mean Nemerow integrated pollution index = 8.09), primarily driven by Au, Ag, Mo, W, and Cu. Vegetation surveys identified 34 vascular plant species from 12 families. Propylite-derived substrates supported significantly higher species richness, Shannon–Wiener diversity, and soil organic matter than porphyry and siltstone. Redundancy analysis (RDA) identified soil organic matter (SOM) and bulk density (BD) as dominant environmental filters, with SOM explaining 14.03% of community variance (p < 0.01). Two native pioneers, Potentilla supina and Cynoglossum wallichii, were identified as specialized uranium (U) accumulators with bioconcentration factors of 13.39 and 4.49, respectively. Lithological inheritance dictates early successional trajectories by influencing edaphic structure and nutrient bioavailability. The identified U-accumulating species provide a valuable genetic resource for implementing Assisted Natural Regeneration (ANR) and developing sustainable phytoremediation strategies in contaminated alpine ecosystems. Full article

The expansion of the invasive species Pedicularis kansuensis threatens the ecological integrity of alpine wetlands, particularly in the Bayinbuluke, northwestern China. However, operational monitoring remains challenging. Conventional indices often lack specificity in heterogeneous alpine backgrounds, while deep learning models are typically too data-intensive to support consistent, multi-year mapping. To develop a rapid, reliable, and operational method for monitoring this invader, we proposed a novel, species-specific spectral index, the Pedicularis kansuensis Index (PKI), using the blue, green, and red-edge bands of high-resolution (3 m) PlanetScope imagery. The PKI constructs a robust target signal by integrating distinct spectral features derived from in situ hyperspectral measurement with a grayscale morphological opening (GrMO) refinement to suppress background noise. A comprehensive validation against seven established benchmarks indices (e.g., NDVI, RI, and ARI) demonstrated the superior performance of PKI across the central alpine wetlands of Bayinbuluke (2841 km²). It achieved the highest separability with an M-statistic of 1.36. Furthermore, the index attained an overall accuracy of 93.52% (95% CI: 92.3–94.7%), and an F1-score of 93.28% (95% CI: 92.0–94.5%), effectively minimizing confusion with co-occurring native vegetation and background. Applying this framework to a five-year time series (2021–2025) revealed a distinct cycle of outbreaks and relaxation. Specifically, the invaded area increased to 2168 ha in 2022, then decreased to 160 ha in 2025. Spatial analysis further identified stable invasion hotspots of 161.6 ha, highlighting key targets for long-term containment. Meanwhile, 94.4% of the invaded area was transient, lasting only one year (4824.7 ha). These results confirm that the PKI is a physically interpretable, accurate, and computationally efficient tool for monitoring invasive species in heterogeneous alpine environments. It facilitates timely and targeted ecosystem management. Full article

Phosphorus deficiency is a key factor limiting plant growth in desertified grasslands. Elucidating the adaptive strategies of pioneer plants that integrate root morphology and microbial interactions is crucial for understanding the natural restoration of ecosystems. This study investigated the strategies employed by Kengyilia hirsuta, a pioneer grass species in desertified grasslands, to adapt to low-phosphorus environments. By conducting sand culture experiments under varying phosphorus levels (low, optimal, and high), we focused on elucidating the synergistic adaptive mechanisms involving the root–rhizosheath system. The results showed that the rhizosheath serves as a critical micro-ecological niche for enriching arbuscular mycorrhizal fungi (AMF) and enhancing phosphatase activity. Under low-phosphorus stress, the plant strengthened root hair development and its symbiotic association with AMF, which markedly increased acid phosphatase activity and led to the highest phosphorus use efficiency. At the optimal phosphorus level, the plant developed an efficient “rhizosheath–mycorrhiza” synergistic system, characterized by high AMF colonization and spore density, facilitating optimized carbon–phosphorus exchange. Under phosphorus-sufficient conditions, the adaptive strategy transitioned towards root morphological plasticity, exemplified by increased surface area and branching. Multivariate analysis revealed that the phosphorus absorption efficiency of K. hirsuta is co-regulated by both morphological adaptation and symbiotic optimization. This study elucidates the mechanisms of nutrient stress adaptation in desertified grassland plants, providing a theoretical foundation for understanding the natural restoration processes of degraded ecosystems. Full article

Disparities in root fungal endophyte (RFE) communities are well documented among plant species, yet differences among plant functional groups (PFGs) remain unclear. Given that RFE community structure is influenced by host plant abundance and species-specific root functional traits, and that PFGs exhibit divergent relative abundances and root traits, we hypothesize that PFGs harbor unique RFE communities, potentially aligned with their functional traits. We investigated RFE communities in 45 alpine meadow species representing four PFGs (grasses, legumes, dicot forbs, and monocot forbs), using high-throughput sequencing. Ascomycota dominated all groups (>50%) except monocot forbs (38.9%). Distinct differences in the RFE community species composition were found among PFGs. In particular, the differences were significant between dicot forbs and monocot forbs, and between monocot forbs and grasses, which contradicted with conventional PFG classification that combined monocot and dicot forbs as a single PFG. Moreover, marker operational taxonomic units (OTUs) with symbiotic lifestyles were more abundant in legumes, and their functional composition differed significantly from grasses. Roots’ nitrogen concentration was the strongest predictor of RFE variation, followed by root length, biomass, and species abundance. These results emphasize the importance of integrating microbial partners into understanding plants’ functional diversity and ecosystem resilience in alpine environments. Full article

Emerging contaminants (ECs) comprise diverse pollutant classes that are increasingly detected in remote environments due to their persistence and long-range transport potential. In cold regions, atmospheric cold-trapping processes favour their accumulation in high-altitude and high-latitude snow and ice, which act as sensitive archives and secondary sources of contamination. While previous studies have addressed individual environmental compartments (e.g., snowpack, glacier ice, meltwater), focusing on specific contaminant classes, a systematic review integrating the occurrence, behaviour and impacts of major EC groups in polar and alpine snow and ice is still lacking. To fill this gap, this work synthesised current knowledge on the environmental fate of three key EC categories in the cryosphere: metals and metalloids (MMs), industrial chemicals and by-products (ICBs), and pharmaceuticals and personal care products (PPCPs). PRISMA guidelines were accurately followed for research, which was based on a Google Scholar search combining keywords on cryospheric matrices (snow, firn, ice cores), geographical regions (Arctic, Antarctic, Alps, high mountains), and contaminant classes. Of 350 records initially identified, 300 met the eligibility criteria (post-industrial snow, firn, or ice cores studies) after excluding studies focused on aerosol or meltwater-only, method-focused papers, pre-industrial datasets, urban-only investigations, and duplicates. Risk of bias was qualitatively assessed through manual screening, evaluating matrix eligibility, temporal consistency, analytical methods, detection limits, and duplicate data, with particular attention to inconsistencies in ECs classification. Strict operational definitions were therefore applied to ensure methodological coherence. Concentration data were harmonised into a standardised database, and findings were synthesised through a structured narrative supported by tabulated datasets organised by matrix and site. Overall, the evidence indicates widespread occurrence of ECs in the global cryosphere, with spatial variability linked to emission sources, long-range transport pathways, and snow physicochemical properties. Climate-change-driven alterations of snow dynamics, glacier retreat and permafrost thaw are expected to modify partitioning equilibria and enhance the secondary release of legacy and contemporary contaminants. However, significant limitations persist, including geographical gaps, variability in analytical sensitivity, lack of long-term monitoring for certain EC classes, and inconsistencies in contaminant classification frameworks. Despite these constraints, the synthesis highlights consistent emerging patterns and underscores the need to strengthen existing environmental protocols to mitigate potential risks to ecosystems and human health. Full article

Freeze–thaw cycles on the Qinghai–Tibetan Plateau inhibit microbial activity and challenge silage preservation. This paper aimed to elucidate how an indigenous, freeze–thaw-resistant Lactobacillus plantarum strain (LP160) improves oat silage quality under such stress. Oats were ensiled for 60 days under constant 20 °C (t) or freeze–thaw cycles (12 h at 20 °C/−5 °C; s) with or without LP160 inoculation. Samples after ensiling and 5-day aerobic exposure were analyzed for fermentation parameters, nutrients, microbiome, and non-targeted metabolomics using liquid chromatography–tandem mass spectrometry (LC-MS/MS). LP160 inoculation improved silage quality, as shown by the lower pH, ammoniacal nitrogen, neutral detergent fiber, acid detergent fiber contents as well as the greater amount of lactic acid. Key findings demonstrated that LP160 inoculation significantly enhanced Lactobacillus dominance, effectively curbed the growth of detrimental bacteria like Mucor, and regulated the microbial structure. During the aerobic exposure phase, the microbial community structures and successions varied under different temperature treatments. When inoculated under freeze–thaw conditions, the genus Bacillus increased, while Paenibacillus was not impeded. A total of 943 metabolites were identified, predominantly comprising amino acids, fatty acids, and the like. The expressions of metabolites with antioxidant and antibacterial properties were upregulated with LP160 inoculation. This led to the inhibition of protein hydrolysis and a reduction in ammonia–nitrogen production. The results of correlation analysis indicated that inoculating LP160 suppressed the proliferation of Mucor and enhanced the abundance of Torulaspora; meanwhile, the expression of L-palmitoylcarnitine involved in the fatty acid degradation pathway and fatty acid metabolism pathway was inhibited along with the generation of ammonia–nitrogen. Consequently, the degradation of fatty acids and proteins was restrained. The results of this paper provided new insights into the silage under freeze–thaw conditions. Full article

This study employed integrated transcriptomics and proteomics analysis to investigate the potential role of methionine (Met) in regulating the proliferation, differentiation, and lipid deposition of yak intramuscular preadipocytes (YIMA). Five Met concentrations (0, 0.05, 0.5, 5, and 50 mM) were used to establish the Met model of YIMA. The results of Bodipy, Oil Red O, EdU staining, and qPCR showed that the appropriate Met (0.05, 0.5, and 5 mM) supplementation significantly promoted the proliferation and adipogenic differentiation of YIMA, whereas excessive Met (50 mM) markedly inhibited these processes. To further evaluate the mechanism of Met on YIMA, cells supplemented with 0 mM (control, CON), 0.5 mM (moderate) and 50 mM (excessive) Met were selected for the transcriptomic and proteomic analyses. The results showed that moderate Met treatment primarily enriched pathways related to extracellular matrix–receptor interaction and the PI3K/AKT signaling pathway, while excessive Met significantly enriched processes involving abnormal methylation, DNA damage, and metabolic stress. Functional validation experiments further confirmed that Met regulates YIMA proliferation and differentiation by upregulating p-Akt protein expression and activating the PI3K/AKT pathway. These findings provide molecular insights that support improving yak meat quality and IMF content through dietary Met supplementation. Full article

Monoculture and mixed sowing are common practices for restoring degraded alpine meadow grasslands. To investigate the effects of different sowing patterns on soil bacterial community characteristics in alpine artificial grasslands, this study examined a 20-year-old established artificial grassland, systematically analyzing plant community attributes, soil physicochemical properties, and the diversity and functional structure of soil bacterial communities under various monoculture and mixed-sowing treatments. The results showed that: (1) Mixed-sowing treatments significantly improved soil physicochemical properties and plant community characteristics. The P4 (Elymus nutans + Poa pratensis + Festuca sinensis + Poa crymophila) mixed-sowing treatment notably enhanced vegetation performance and soil conditions. Compared with the monoculture P1 (Elymus nutans) treatment, aboveground biomass (AGB) and soil organic matter (SOM) content increased by 57.23% and 68.25%, respectively, indicating that perennial grass mixtures improve soil water and nutrient retention, thereby promoting plant growth. (2) Microbiome analysis revealed that mixed sowing significantly optimized the structure of rhizosphere bacterial communities. Operational Taxonomic Units (OTUs), which represent sequence-based taxonomic units and their abundance information, were most abundant in the P4 mixed-sowing treatment, reaching a total of 5685 OTUs. In terms of bacterial diversity indices, the OTU richness, Ace index, and Chao1 index in the P4 mixed-sowing treatment were 26.12%, 25.81%, and 24.34% higher, respectively, than those in the monoculture P1 treatment, with all differences being statistically significant (p < 0.05). (3) Mantel test and redundancy analysis (RDA) revealed that soil electrical conductivity (SEC) and pH were negatively correlated with bacterial diversity indices, while soil organic matter (SOM) was identified as the key environmental driver shaping bacterial community assembly. In summary, appropriate grass mixtures effectively enhance “plant–soil–microbe” interactions, leading to improved soil fertility and optimized bacterial communities, representing a viable strategy for long-term ecological restoration and sustainability of alpine artificial grassland ecosystems. The P4 treatment—comprising a four-species mixture of Elymus nutans, Poa pratensis, Poa crymophila, and Festuca sinensis—achieved the best overall performance. Full article

Understanding how plant physiological traits respond to environmental variation is essential for explaining plant performance in alpine ecosystems. Based on field sampling along an elevational transect on the Tibetan Plateau, we quantified osmotic adjustment compounds, antioxidant indicators, and plant hormones in leaves of different species to examine interspecific differences in sensitivity to temperature and precipitation to characterize patterns of physiological plasticity among alpine plants. Along the elevational gradient, declining temperature results in increasing cold stress, whereas lower elevations are associated with reduced precipitation and intensified drought stress. Temperature primarily influenced plant physiological trait expression by promoting growth-related physiological processes, while precipitation variability mainly regulated traits associated with water stress. The three dominant alpine meadow species exhibited distinct patterns of physiological plasticity: Poa litwinowiana showed coordinated regulation of growth and defense pathways, whereas Carex moorcroftii and Carex parvula displayed more conservative response strategies, with physiological regulation tending to maintain homeostasis rather than strongly activating stress responses. These interspecific differences in physiological regulation were significantly associated with variations in plant height, cover, and dominance, providing trait-level physiological insights relevant to plant performance. Full article