Organic amendments (OA) enhance soil organic carbon (SOC) stocks and mitigate erosion in sloping farmlands under intense urban-agricultural pressure. However, the mechanisms underlying OA-regulated SOC redistribution and stabilization remain unclear. This study investigated the key regulatory role of OA in modulating SOC fractions and dissolved organic matter (DOM) humification in southwest China's sloping farmlands using a long-term field experiment with three treatments: chemical fertilizer only (CK), organic fertilizer (OF), and organic fertilizer combined with straw returning (OFSW). Results showed that erosion caused spatial heterogeneity in SOC fractions, with particulate organic carbon (POC) loss on upper slopes and mineral-associated organic carbon (MAOC) accumulation downslope. OA application significantly increased SOC and aggregate stability under both OF and OFSW. Specifically, POC on the upper slope under OA treatments was over 3.7 times higher than CK, while the downslope increased by 0.7-1.4 times. OF preferentially enhanced DOM humification and MAOC preservation, while OFSW more effectively retained SOC on upper slopes and increased labile POC downslope. PARAFAC modeling identified humic-like DOM enrichment linked to SOC stabilization. Partial least squares path modeling revealed OA's synergistic regulation of SOC through physical protection and chemical stabilization pathways. These findings highlight tailored OA strategies as effective for mitigating erosion-induced SOC loss and enhancing carbon sequestration in sloping agroecosystems.

ABSTRACT Understanding and quantifying the dietary composition of large carnivores is crucial for elucidating their functional roles within ecosystems including their top–down regulation of prey populations and their interactions with sympatric carnivore species. In this study, we employed DNA metabarcoding to analyze the vertebrate components of the diets of three sympatric large carnivores, snow leopard Panthera uncia, wolf Canis lupus, and brown bear Ursus arctos, with particular emphasis on assessing potential interspecific competition in the Sanjiangyuan Region (SR) of the Qinghai–Xizang Plateau. Analysis revealed 11, 16, and 17 prey species in the diets of wolves, snow leopards, and brown bears, respectively. Domestic yak (Bos grunniens) was the most frequently detected prey item in the diets of both wolves (Relative Read Abundance; RRA = 52.29%) and snow leopards (RRA = 25.42%), whereas brown bears primarily consumed plateau pikas (Ochotona curzoniae; RRA = 43.10%) and Himalayan marmots (Marmota himalayana; RRA = 19.88%). Although high dietary niche breadth overlap was observed between snow leopards and wolves (Ojk = 0.76) and between snow leopards and brown bears (Ojk = 0.79), potential interspecific competition may be mitigated through differential prey selection and varying consumption intensities. The relatively low dietary overlap between wolves and brown bears (Ojk = 0.32) implies that these two species likely coexist by partitioning trophic resources. Moreover, the substantial proportion of livestock found in the diet of these large carnivores indicates potential presence of significant human–carnivore conflict in the SR. Combined with previous findings, our results support the hypothesis that the abundance and size‐class availability of ungulate prey are key factors enabling the sympatric existence of these three apex predators.

Forest fires are key ecological disturbances that influence vegetation dynamics and soil microbial processes central to carbon and nutrient cycling. While fire frequency and severity are increasing globally, the microbial mechanisms underlying ecosystem recovery remain inadequately understood. We used high-throughput amplicon sequencing to evaluate short-term effects of low- and high-severity fires on soil microbial diversity and co-occurrence networks following fire disturbance in a temperate forest. Fire severity had no significant impact on microbial alpha-diversity, but significantly altered beta-diversity. Mantel tests indicated that soil pH and belowground biomass were the primary environmental drivers of bacterial and fungal community turnover under different fire severities. Further, network analyses revealed distinct microbial responses to fire severity: low-severity fire primarily restructured bacterial associations, whereas high-severity fire disrupted both bacterial and fungal networks. These findings suggest that microbial community structure and interactions are differentially sensitive to fire severity, with implications for soil functional resilience and ecosystem restoration strategies in fire-affected forests.

Pomegranate (Punica granatum L.), a high-value fruit crop widely cultivated in semi-arid and semi-humid regions, has driven large-scale conversion of conventional croplands into orchards in response to rising global market demand. However, the ecological impacts of this land-use change, particularly how stand age influences the composition and structure of soil nematode communities, remain poorly understood. Using a chronosequence approach, we investigated the effects of orchard establishment on soil nematode communities across different stand ages (1, 3, 5, and 10 years after establishment), with adjacent croplands serving as reference. Compared to conventional farmland, one-year-old plantations exhibited a 53.08% reduction in bacterivorous nematodes and a striking 316.73% increase in fungivorous nematodes (P < 0.05). Stand age significantly affected the Pielou evenness index, nematode channel ratio, maturity index, and basal index of the soil nematode community. Total nematode metabolic footprints, as well as enrichment footprint and structure footprint, peaked in 5-year-old orchards. Pearson correlation analysis revealed that the relative abundance of bacterial feeders and the nematode channel ratio were significantly negatively correlated with soil total phosphorus content. The maturity index was positively correlated with soil fungal biomass. NMDS ordination indicated that stand age is a primary driver of nematode community composition, while RDA analysis identified soil total phosphorus, carbon, nitrogen, fungal microbial biomass as key explanatory variables. Our results demonstrate that the age of pomegranate orchards drives significant successional shifts in soil nematode community structure and function, reflecting age-dependent ecosystem development in orchard soils. This study identifies the five-year stage as an ecological tipping point characterized by peak biological activity and optimal nutrient cycling efficiency. These insights support the design of precisely timed management interventions to prolong this productive phase, offering practical strategies for maintaining long-term soil health in orchard ecosystems.

Soil beta-1,4-glucosidase is a key enzyme involved in microbial cellulose degradation and the terrestrial carbon cycle. However, reliable determination of its potential activity is often hampered by methodological uncertainties arising from a lack of explicit knowledge regarding the standardized requirements for incubation and soil sample storage conditions across different studies. To evaluate these sources of variation, we quantified soil potential beta-1,4-glucosidase activity using a fluorometric microplate assay across three contrasting soil types (Acrisols, Luvisols, and Calcisols), three incubation temperatures (10, 20, and 30 degrees C), three incubation durations (1, 4, and 12 h), and two soil sample storage conditions (-20 degrees C and air-drying). Among the experimental treatments, incubation temperature emerged as the primary factor regulating soil potential (3-1,4-glucosidase activity, with more than a 60% increase as temperature rose from 10 to 30 degrees C. This temperature effect did not vary with incubation durations, storage conditions, or soil types. Incubation duration interacted strongly with both storage condition and soil type; likewise, the effect of storage condition was modulated by soil type. These findings challenge the universality of common methodological assumptions by demonstrating that the influence of incubation duration and storage condition is modulated by their interactive effects and respective interactions with soil type. Standardization of soil potential (3-1,4-glucosidase activity assays requires strict control of incubation temperature while adjusting incubation duration and storage condition in accordance to soil type for multi-site comparison studies. Our study provides a methodological framework that improves the reliability and comparability of soil potential (3-1,4-glucosidase activity assays, thereby enhancing their application in studies of soil carbon cycling.

Soil organic carbon (SOC) loss driven by water erosion poses a dual threat to agricultural biogeochemical cycles and global carbon balance. While soil microbial communities are known to respond to erosion, their adaptive strategies and the consequent impacts on the fate of SOC across soil profiles in various positions of eroded landscapes remain poorly understood. This study integrated observations from 0–100 cm soil profiles in the upper (eroding) and lower (depositional) slope positions in northeastern China's black soils to investigate the adaptive responses of soil microbiomes to water erosion stress and their cascading effects on SOC decomposition. Water erosion induced distinct microbial adaptive strategies across soil depths, with major changes occurring in the topsoil (0–40 cm) whereas the fate of SOC deeper in soil was unaffected. Erosion reduced SOC content in the upper slope, particularly in the 2–10 μm colloidal soil particles by 30

【Objective】Continuous monoculture in orchards can lead to soil degradation and nutrient imbalances, compromising fruit yield and sustainability. Applying organic soil conditioners can alleviate these detrimental effects. This paper presents the results of an experimental study on the combined effects of applying organic soil conditioner and hydrogen-rich water on soil nutrient fertility in a kiwifruit orchard.【Method】The experiment included six treatments: no fertilization (CK), conventional fertilization + conventional irrigation (NW), conventional fertilization + irrigation with hydrogen-rich water (NM), application of organic soil conditioner + irrigation with conventional water (BW), application of organic soil conditioner + irrigation with hydrogen-rich water (BM), and application of 50 % organic soil conditioner and 50% conventional fertilizer + irrigation with hydrogen-rich water (HBNM). During the experiment, we measured soil physicochemical properties, nutrient contents and soil fertility. The effects of the treatments on soil fertility were evaluated using the Nemerow composite index combined with analysis of key driving factors.【Result】Fertilization significantly increased soil nutrients, including total nitrogen (TN) and total phosphorus (TP), compared to CK. Among all treatments, BM achieved the highest integrated fertility index (IFI = 2.84) and the greatest increases in SOC and available nutrients; it also enhanced nutrient accumulation and biological activity in the soil. HBNM gave the lowest IFI, indicating diminished nutrient supply. The contribution of various factors to soil fertility was ranked in the order AP (available phosphorus)＞AN (available nitrogen)＞TP＞TN＞SOC (soil organic carbon)＞pH＞TK (total potassium)＞AK (available potassium). SOC was positively correlated with TN, TP, AP, and AK (P＜0.001), and negatively correlated with pH (P＜0.001), underscoring its importance in soil fertility.【Conclusion】Applying soil conditioner and hydrogen-rich water can effectively improve soil physical and chemical properties, significantly increase nutrient contents and enhance overall soil fertility. It can be used as an improved cultivation practice for sustainable kiwifruit production.

Climate warming threatens the cryosphere across cold regions, which include glaciers, permafrost, snow cover, and sea ice. Permafrost thaw has occurred in recent decades in Arctic regions, as well as in alpine regions. The potential release of a large amount of organic carbon could further accelerate global warming. Here we summarize recent progress related to the storage, source, composition, stabilization, and emission of permafrost carbon in the Arctic and Third Pole regions. By combining previous data syntheses and model estimations, we conclude that the soil organic carbon storage for the 0u2013300 cm layer of soil is approximately 985.8 u00B1 98.7 Pg C in the Northern Circumpolar permafrost regions and 23.5 u00B1 11.1 Pg C in the Qinghai-Tibet permafrost region. The projection of the ecosystem model shows that the carbon emissions from permafrost due to warming is expected to reach as high as 240 Pg C by 2100, with an average of 92 u00B1 17 Pg C. Finally, we present some priorities for permafrost carbon research, including the long-term and continuous observation of carbon dynamics, improvement of the ecosystem model to reduce uncertainties in projections, and the application of advanced techniques such as machine learning or deep learning, to achieve a more accurate assessment of the response of carbon dynamics to climatic warming in the future.

Microplastics persisting in soil can modify soil structure and nutrient status and alter biological activity, thereby influencing soil respiration. However, the mechanisms by which microplastics regulate soil respiration remain poorly understood. In this study, a field experiment was conducted in a winter wheat farmland to examine the effects of microplastic type (polypropylene and polyethylene) and particle size (13 and 500 mu m) on soil respiration and to identify the associated driving factors. Soil respiration was significantly increased by microplastics, with a greater impact observed for 13 mu m than for 500 mu m microplastics. Microplastics increased root biomass and microbial biomass carbon, whereas they reduced aboveground biomass and soil available nitrogen content. Structural equation modeling indicated that the microplastic-induced increment in soil respiration was primarily driven by root biomass. Microplastics stimulated root growth by changing soil physical structure, such as reducing bulk density, increasing soil porosity, and altering aggregate stability, thereby promoting soil respiration. Overall, this study highlights that microplastics can substantially alter belowground carbon dynamics by reshaping plant-soil-microbe interactions, and provides a scientific basis for evaluating the ecological consequences of microplastic pollution in agricultural soils.

Ecosystem multifunctionality (EMF) serves as an integrated indicator of nutrient cycling, water regulation, and productivity in agroecosystems, exhibiting high sensitivity to cover crop management. Soil biodiversity underpins essential ecosystem services essential to human well-being. However, cover cropping exerts complex effects on soil abiotic conditions and the diversity of soil microbes, nematodes, and earthworms, introducing uncertainty regarding its regulation of EMF. This study investigated how ryegrass (Lolium perenne L.) cover cropping duration influences EMF in apple orchards on the eastern Loess Plateau. Compared to clean tillage, ryegrass cover cropping significantly enhanced soil carbon, nitrogen, and phosphorus cycling functions, productivity, and overall EMF. These benefits followed a unimodal trajectory, peaking at approximately 5 years post-establishment before declining. Crucially, multitrophic biodiversity exerted a stronger influence on EMF than diversity within any single trophic level. Collectively, soil microbes, nematodes, and earthworms explained 74% of the variation in EMF, with smaller, lower-trophic organisms contributing more substantially than larger, higher-trophic organisms. Structural equation modeling identified soil organic carbon and available nitrogen, rather than soil pH, as the primary abiotic drivers of EMF under ryegrass cover cropping. Our findings demonstrate that cover cropping-induced nutrient changes cascade through soil food webs, shaping multitrophic diversity and thereby regulating EMF. These observations highlight that maintaining cover crops for approximately 5 years optimizes EMF, providing targeted guidance for sustainable apple orchard management on the eastern Loess Plateau.

ABSTRACT Vegetation restoration has been widely used to curb desertification in northern and central desert shifting sandy lands of China. However, the general pattern, variability, and drivers of its effects on soil organic carbon (SOC) remain unclear. Here, we conducted a meta‐analysis by synthesizing 332 paired observations from 32 publications to quantify the effects of vegetation restoration on SOC and to examine whether they were regulated by restoration characteristics (methods and durations) and edaphic‐climatic conditions in northern and central desert shifting sandy lands of China. Overall, vegetation restoration significantly increased SOC in shifting sandy lands at the regional scale, but the magnitude of SOC responses varied across restoration methods, restoration durations, soil depths, and desertification types. In particular, it was greatest in tree‐planted areas compared to other vegetation restoration methods, followed by shrub‐planted, herb‐sown, and enclosed areas; it displayed a positive relationship with restoration duration. We preliminarily found that SOC responses were stronger in surface soil and deep subsoil, while relatively weaker in middle soil layers. In addition, SOC was most pronounced in deserts, followed by degraded grassland, transitional zone, and desert steppe types. Random forest modeling and structural equation modeling revealed that soil sand fraction was the primary driver of SOC responses, followed by mean annual precipitation and restoration method. Soil physical properties (e.g., sand fraction, bulk density) were closely associated with SOC responses, while climate factors and restoration duration exerted indirect correlative influences on SOC responses via modifying soil physical properties. Overall, our study illuminated the divergent multidimensional responses of SOC to vegetation restoration in shifting sandy lands in northern and central Chinese desert shifting sandy lands and identified soil sand fraction and mean annual precipitation as the major regulatory factors of SOC responses. These findings can provide a fundamental basis for achieving coordinated advancement of regional desertification control and national carbon neutrality goals.

The temperature parameter of scenting process, which governs the vitality of fresh flowers and the release of floral volatiles, is still empirically determined. Here, we investigate how environmental temperature regulates osmanthus vitality and enzymatic activity to shape the aroma quality of osmanthus black tea (OBT). Results showed that the moderate-temperature (25 °C and 30 °C) exhibited superior sensory quality, accompanied by slower water loss and delayed wilting of osmanthus, which favored aroma retention during scenting. Carotenoid cleavage dioxygenase (CCD) content peaked (1268 U/g), associating with the accumulation of β-ionone (a typical floral aroma), while β-glucosidase (β-GC) activity gradually increased with rising temperature, contributing to the formation of esters such as γ-decalactone (fruity aroma). Volatile profiling revealed that 30 °C promoted the accumulation of multiple key volatile compounds (linalool, β-ionone, and γ-decalactone), resulting in the highest total volatile content and overall odor activity value (OAV). In contrast, low temperature (20 °C) maintained flower freshness but limited aroma-related enzymatic responses and volatile accumulation. High temperature (35 °C) caused rapid petal dehydration (over 73% water loss within 4 h) and premature withering, inhibiting aroma release and reducing total volatile content. Overall, these findings establish 30 °C as the optimal environmental temperature for scenting OBT and provide a flower-centric, physiologically grounded strategy for temperature control.

Abstract Northern high-latitude permafrost is facing unprecedented wildfire disturbances, driving an anomalous regional increase in annual carbon emissions (8.1 ± 2.9 TgC yr⁻¹ from 1997 to 2023) against a backdrop of declining global wildfire emissions. To elucidate these complex dynamics, this review conceptualizes the “Permafrost Critical Zone” (PCZ) and adopts a holistic Earth-system perspective to evaluate the cascading impacts of wildfires on vulnerable cryospheric landscapes. We synthesize how fire-induced organic layer combustion and surface albedo reduction destabilize the PCZ, drastically elevating ground surface temperatures by up to 7 °C and deepening the active layer by up to six times. These severe thermal shocks fundamentally rewire hydrological pathways, accelerating ground ice melt, altering supra-permafrost water storage, and amplifying surface runoff. Concurrently, wildfires abruptly reduce microbial diversity and restructure cold-adapted biological communities, initiating divergent post-fire vegetation succession trajectories. While ecological and hydrothermal recovery is essential for restoring carbon and water fluxes, the compounding effects of repeated fires under a warming climate threaten to irreversibly degrade these environments. We conclude by highlighting critical knowledge gaps and emphasizing the necessity of integrating PCZ dynamics into global models to predict impending climate tipping points and to inform long-term sustainable development strategies.

Farmland wind erosion causes significant losses of soil organic carbon (SOC) and essential nutrients, reducing soil fertility, diminishing crop yields, and causing long-term environmental degradation. Unclear relationships between nutrient losses and fertilizer compensation hinder effective soil conservation strategies. Here, we quantified the losses of SOC, nitrogen (N), and phosphorus (P) using the parameterized Wind Erosion Prediction System (WEPS) model for the North China Plain (NCP). Model validation showed a strong correlation between simulated and observed dust fluxes (R = 0.80, RMSE = 0.98 g m(-2) 30s(-1), p < 0.001), confirming its reliability in the NCP. Results indicated that approximately 0.162 t km(-2) of SOC, 0.018 t km(-2) of N, and 0.015 t km(-2) of P were lost annually, threatening soil fertility and productivity. Compensating these losses solely with fertilizers would require 0.038 t km(-2) of urea and 0.212 t km(-2) of superphosphate each year. These findings provide critical insights for policymakers and farmers in implementing sustainable land management strategies to mitigate soil degradation.

Plateaus, which host numerous glaciers, are recognized as critical reservoirs of global groundwater storage (GWS). Although GWS has been widely investigated at regional and global scales, a comprehensive assessment of GWS dynamics across global plateau regions (GPR) remains lacking. Here, GWS anomalies across GPR were reconstructed from 2002 to 2022 using GRACE and GRACE-FO observations combined with GLDAS-derived hydrological components. The reconstructed GWS was further validated against the Mascon solution and an independent GWS product, demonstrating strong consistency among different datasets. The results reveal that GWS in global plateaus has been undergoing an accelerating decline, accompanied by pronounced spatial and temporal heterogeneity in both amplitude and phase. On average, plateau regions have experienced a GWS decline of −0.213 ± 0.027 cm/yr, with the steepest reductions recorded in North America (−0.816 ± 0.061 cm/yr) and Europe (−0.579 ± 0.085 cm/yr). In contrast, major high-altitude lakes exhibit a modest increase in water storage (0.103 ± 0.03 cm/yr), thereby partially compensating for groundwater declines. Our findings provide new insights into GWS dynamics across GPR and offer scientific support for sustainable groundwater management under ongoing climate change.

Microbial extracellular enzymes are key indicators of soil biogeochemical functioning, yet their sensitivity to storage conditions remains unclear and limits cross-study comparability. We evaluated how three storage conditions (−20 °C, air-drying, and freeze-drying) affect hydrolytic and oxidative enzyme activities across forest soils spanning an acidic-to-alkaline pH gradient in China (Acrisols, Luvisols, and Calcisols). Storage at −20 °C consistently preserved higher hydrolytic activities, whereas air-drying and freeze-drying caused significant reductions across all soils. Conversely, oxidative enzymes showed soil-specific responses: -20 °C was optimal for Acrisols; both -20 °C and freeze-drying outperformed air-drying in Luvisols; while storage conditions little affected Calcisols. Multivariate analysis revealed that, although both enzyme types were influenced by key soil properties (e.g., pH, carbon, nutrients), their primary drivers differed. Hydrolytic activities were predominantly governed by storage conditions, whereas oxidative activities were mainly regulated by climatic factors (temperature and precipitation). These findings underscore the necessity of tailoring storage protocols to specific soil and enzyme types. Standardizing and explicitly reporting these conditions will improve the reproducibility of enzyme assays, providing a robust methodological foundation for future ecological research.

Agricultural residues can serve as organic amendments to enhance soil fertility and soil biodiversity. However, the relative efficacy of fresh versus dried straw clippings in modulating soil microhabitats and microarthropod communities in semi-arid regions remains inadequately quantified. Here, a field experiment (2021-2024) was conducted in a semi-arid region to investigate the effects of fresh and dried plant clippings amendments on soil microhabitats and microarthropod diversity, structure, morphology, and function, with assessments carried out during the third and fourth years after initial application. Results showed that both plant clippings amendments significantly increased soil organic matter (fresh: +22.6%; dried: +16.3%), porosity, and water storage, while reducing temperature. Fresh clippings amendment also raised soil moisture (+17.9%) and lowered pH value. Correspondingly, fresh clippings amendment increased microarthropod abundance, richness, and body size more strongly than dried clippings amendment, and increased the Abundance-based Fauna Index (FAI) by 151.7% (over four times the effect of dried amendment). Microarthropod community structure shifted toward saprophagous dominance, and exhibited lower interspecies heterogeneity under fresh clippings amendment. Redundancy and random forest analyses showed soil organic matter and microarthropod richness as the foremost predictors of FAI. Structural equation modeling further indicated that plant clippings amendments enhance FAI primarily indirectly by increasing soil organic matter and microarthropod richness. These findings demonstrate that fresh plant clipping amendment is more effective than dried amendment in improving soil microhabitats and enhancing microarthropod diversity, morphology, and function. This contributes to stabilizing the soil food web and improving fauna quality, thereby providing a scientific basis for sustainable organic management in semi-arid agricultural ecosystems.

Abstract Soil extracellular enzymes are essential regulators of biogeochemical cycles, yet the conditions under which their activities are assayed, particularly incubation temperature, remain poorly standardized. This variation among studies can introduce substantial bias and complicate cross-study comparisons. Here, we examined hydrolase and oxidase activities across different soil pH conditions, with samples separately incubated at 10, 20, and 30 °C in acidic, neutral, and alkaline forest soils. Our results showed that hydrolase activities increased with increasing incubation temperature, though the pattern differed among soil pH conditions. In acidic soil, hydrolase activities were lower at 10 °C compared to 20 and 30 °C, with little difference between 20 and 30 °C. In contrast, neutral and alkaline soils showed a continuous increase in hydrolase activities from 10 to 30 °C. When data from all soils were combined, oxidase activities displayed no overall temperature effect. However, distinct pH-specific trends emerged: in acidic and neutral soils, oxidase activities increased with incubation temperature, whereas in alkaline soils it declined at higher temperatures. Across all incubation temperatures, soil pH was the primary environmental driver of both hydrolase and oxidase activities, whereas incubation temperature itself exerted no significant influence. This strong soil pH dependence masked the temperature effect, highlighting that pre-existing soil conditions fundamentally influenced the enzymatic thermal response. We propose a decision-making framework that selects incubation temperatures based on soil pH and enzyme class to improve the accuracy and cross-study comparability of measurements of soil extracellular enzyme activities.

Mongolia has experienced increasingly extreme climate events in recent years. Most previous studies have used data from meteorological stations with uneven spatial coverage and inconsistent time series, resulting in an insufficient understanding of regional variations in extreme climate events. In particular, the characteristics of extreme climate events in the two relatively warm years of 2022 and 2023 need to be investigated. Analysis using the ERA5-Land reanalysis data revealed that the hottest day (TXx), coldest night (TNn), coldest day (TXn), extreme warm days (TX90p), summer days (SU25) and the warm spell duration indicator (WSDI) presented increasing trends, whereas the extreme cold nights (TN10p), frost days (FD0) and the cold spell duration indicator (CSDI) presented decreasing trends during 1961 to 2023 in Mongolia. Moreover, the increasing rates of the TXx, TNn, TX90p and WSDI in the permafrost regions (0.042 degrees C/year, 0.049 degrees C/year, 0.244%/year and 0.349 days/year, respectively) were greater than those in the seasonally frozen ground regions (0.031 degrees C/year, 0.044 degrees C/year, 0.223%/year and 0.312 days/year, respectively), indicating that the extreme temperature indices in the permafrost regions were more sensitive to extreme warm events. All extreme precipitation indices showed decreasing trends, with higher values in northern Mongolia, except for consecutive dry days (CDD). In 2022 and 2023, the mean annual air temperature (MAAT), TXx, TX90p, SU25 and WSDI accounted for more than 50% of the TOP_10, and CDD accounted for more than 20%, reflecting more extreme warm events and droughts. Compared with neighbouring regions, Mongolia experienced faster increases in extreme warm events and droughts. The Asian Polar Vortex Intensity Index (AAI), Atlantic Multidecadal Oscillation Index (AMO) and MAAT have the greatest impact on extreme temperature indices, and the annual total precipitation (ATP) has the greatest impact on extreme precipitation indices. These findings help study the hydrological, ecological and social impacts of extreme climate events.

Arid and semi-arid areas are facing serious water challenges, yet a comprehensive understanding of current and future water supply-demand dynamics remains limited, particularly under climate change and intensified human activities. Based on InVEST and statistical models that include various human activities, we analyzed the patterns and variations of water supply and demand on the Mongolian Plateau for the present period (2001-2020) and projected future (2021-2100). The results showed that grasslands and forests were the primary sources of water supply (77.4%), and cropland was the dominant source of water demand (97.5%), the annual water supply and demand were 238.7 m 3 /hm 2 per year and primarily due to increased precipitation and a reduction in irrigation water demand. By the end of the 21st century, water supply is projected to increase across all scenarios, ranging from 20.3% to 30.1%, while demand trends diverge: it declines by 28.9%-33.3% under SSP1-2.6, SSP37.0, and SSP5-8.5, but rebounds to near-baseline levels under SSP2-4.5. Consequently, water security may improve under SSP1-2.6 and SSP5-8.5 but may deteriorate under SSP2-4.5 and SSP3-7.0. We propose region-specific management strategies, including forest conservation, rotational grazing, irrigation optimization, and inter-basin water allocation. The spatially explicit data and findings provide a valuable foundation for