Against the backdrop of global climate change and intensified human activities, grassland soil wind erosion has emerged as a prominent issue threatening ecological security, yet the synergistic driving mechanisms involving multiple factors remain unclear. To systematically reveal the independent and interactive effects of grazing and natural factors on erosion, this study employed a global meta-analysis approach, integrating observational and experimental data from 118 studies to quantitatively assess the effects of grazing, wind speed, precipitation, temperature, and interface layer characteristics. The main results are as follows: (1) Grazing alone significantly increased wind erosion by 14%, and enhanced wind speed was the primary climatic driver, increasing erosion by 13% independently; (2) A strong synergistic effect was observed between grazing and increased wind speed, with their combined impact amplifying erosion by 29%-106%, whereas grazing exhibited an antagonistic interaction with increased precipitation and an additive effect with warming; (3) Degradation of the interface layer (vegetation and soil surface) directly increased wind erosion by 17%-21% and further amplified erosion risk when interacting synergistically with grazing and wind speed, highlighting its core regulatory role. This study is the first to clarify, on a global scale, the key mechanisms by which multiple factors synergistically exacerbate wind erosion and to elucidate the pivotal function of the interface layer in multifactorial interactions, thereby providing a critical scientific basis for developing precise grassland wind erosion prevention and control strategies based on ecological thresholds and adapted to multi-factor interactions.

Intensive grazing can threaten biodiversity and reduce the capacity of grassland ecosystems to sustain multiple ecological functions, particularly in arid regions. How grazing intensity shapes biodiversity, ecosystem multifunctionality, and their interrelationship remains poorly understood. Using a long-term grazing experiment in a desert steppe in northern China, we tested how grazing intensity (at four levels: no, light, moderate, and heavy grazing) affects above- and belowground biodiversity, ecosystem multifunctionality, and their relationship. We found that light grazing increased ecosystem multifunctionality, particularly aboveground multifunctionality. In contrast, moderate and heavy grazing reduced ecosystem multifunctionality, affecting both above- and belowground multifunctionality. For single ecosystem functions, light grazing enhanced productivity, whereas moderate and heavy grazing simultaneously suppressed productivity, carbon cycling, and nutrient supply functions. Notably, under no and light grazing conditions, ecosystem multifunctionality was primarily driven by aboveground diversity, with plant diversity playing a dominant role. In contrast, belowground diversity, especially soil bacterial diversity, became the primary driver of ecosystem multifunctionality under moderate and heavy grazing conditions. Therefore, our findings highlight that the strength and nature of the biodiversity-multifunctionality relationships are shaped by grazing intensity, and light grazing either enhanced or maintained high levels of both biodiversity and ecosystem functioning, offering a promising strategy for sustaining multifunctionality in the desert steppe.

Precipitation is a limiting factor for various system functions in desert steppe ecosystems, and its impacts on aboveground and belowground processes may diverge. To evaluate these differences, for five years, we conducted field experiments to examine the effects of four different precipitation treatments [natural precipitation (WCK), as well as a 50

Nutrient resorption represents a key adaptive strategy for plants in nutrient-poor environments. Grazing exclusion is widely used to restore degraded grasslands; its success ultimately hinges on the population dynamics of dominant species, which drive community structural changes. However, our understanding remains limited regarding how plant nutrient utilization strategies mediated by nutrient resorption regulate these critical population dynamics. A three-year consecutive study investigated the nutrient utilization strategies of dominant species (Stipa breviflora and Cleistogenes songorica) in a desert steppe of northern China across three grazing exclusion durations: long-term (17 years), short-term (5 years), and control (0 years). The results revealed that long-term grazing exclusion significantly increased soil moisture and soil available nitrogen (N) and phosphorus (P) concentrations but decreased soil temperature, indicating that the soil microenvironment is significantly altered in fenced desert steppes. Long-term grazing exclusion significantly reduced N and P concentrations in green leaves of the two species, decreasing nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE), indicating plants had reduced dependence on nutrient resorption after long-term grazing exclusion. Consequently, the reduced relative aboveground biomass of both species demonstrated a weakening of population dominance, indicating that shifts in population dynamics alter community structure in fenced desert steppes. Structural equation modeling showed that grazing exclusion indirectly decreased plant NRE and PRE through increased soil available nutrients, while directly regulating these processes via soil moisture improvement. These ecological processes ultimately decreased the species’ importance values, indicating that grazing exclusion-mediated nutrient supply restructuring reshapes ecosystem structure and function. This study reveals a shift in plant nutrient strategy in fenced desert grasslands from an internal cycling-dominated model to an external access-dominated model and provides a theoretical framework for understanding community succession in fenced grasslands from the perspectives of micro-physiological processes and macro-population dynamics.

Plant quantitative characteristics (QC, namely height, coverage, and standing crop), leaf functional traits (LFT, namely leaf area, leaf dry matter content, and specific leaf area), and CSR strategies (competitive, stress-tolerance, and ruderal strategies) represent the product of plant resource investment and allocation in specific environments. Quantifying how grazing influences these strategies is essential to understanding the mechanisms that sustain desert steppe ecosystems. Using a long-term grazing experimental platform in the desert steppe of Inner Mongolia, this study systematically examined the effects of different grazing intensities-no grazing (CK), light grazing (LG), moderate grazing (MG), and heavy grazing (HG)-on QC, LFT and CSR strategies from a spatial perspective at community level, and further explored their relationships with soil properties. Results showed that increasing grazing intensity significantly reduced leaf area and specific leaf area while increasing leaf dry matter content, indicating a shift in plant strategy from resource acquisition to resource conservation and physical defense. The plant communities were predominantly S-strategy species. Spatially, the heterogeneity of LFT were greatest under MG treatment, while QC and CSR strategies were greatest under LG treatment. The difference in spatial heterogeneity further indicates a hierarchical adaptive mechanism. Soil properties, particularly nitrogen and phosphorus, were identified as key factors driving plant ecological strategies. Grazing-induced soil nutrient limitation forces plants to trade off growth for survival strategies.

Grassland plays a key role in global ecological balance. Grazing, being the tool by which humans utilize grasslands, impacts biodiversity. Using a long-term grazing experimental platform in the desert steppe of Inner Mongolia, this study explored the relationships among grazing intensity, plant diversity, soil nutrients, and microbial diversity, and examined variations in plant and soil microbial diversity under four grazing treatments (no grazing, CK; light grazing, LG; moderate grazing, MG; heavy grazing, HG). It also investigated the correlation between soil nutrients and its diversity, indicating that plant diversity (both species and functional diversity) was the highest under LG and MG treatment. Light grazing enhanced the richness indexes of soil microbial communities (bacteria and fungi), while heavy grazing increased bacterial diversity index. Soil nutrient contents exhibited varying degrees of decline with increasing grazing intensity. Compared to the species richness index, the functional dispersion index was more sensitive to grazing intensity. Additionally, soil bacterial diversity was more responsive to grazing intensity than fungal diversity. Soil total nitrogen mediated the relationship between plant and soil microbial diversity, showing positive correlations with both the plant species richness index and the soil microbial Chao1 index. Therefore, rational regulation of grazing intensity to maintain soil nutrient balance may help mitigate desert steppe degradation and enhance the stability of grassland ecosystems.

Litter decomposition is a key process in ecosystem nutrient cycling. However, how litter quality and nutrient dynamics – particularly those of macro- and microelements – respond to long-term climate warming and nitrogen (N) deposition, and how these responses linked to ecosystem processes such as nutrient cycling and productivity, remain largely unexplored in vulnerable desert steppe ecosystems. In this study, we investigated the legacy effects of experimental warming and N addition on litter mass loss and the dynamics of macro- and microelements, based on a 15-year field experiment conducted in a desert steppe, focusing on the dominant grass species Stipa breviflora. Significant changes in litter mass remaining and nutrient release were observed during the last three years of the experiment (2018–2020). Litter mass loss reached 77.5% under warming conditions. Litter derived from the combined warming and N addition treatment showed higher decomposition rates during the initial stage. Throughout the decomposition process, litter carbon (C), nitrogen (N), and phosphorus (P) contents decreased, whereas manganese (Mn), sodium (Na), and copper (Cu) contents initially increased and then decreased. In addition, litter decomposition rates were positively correlated with C, N, and P contents, and negatively correlated with Mn, Na, and Cu contents. Our findings enhance the understanding of the legacy effects of warming and N addition on litter decomposition and nutrient dynamics, highlight the contrasting responses of macro- versus microelements, and contribute to predicting nutrient cycling and ecosystem stability in arid and semi-arid regions under future global change scenarios.

Desert steppe ecosystems are highly vulnerable to aeolian erosion due to frequent winds and grazing disturbance. However, the synergistic effects and multi-level linkages among climate change, vegetation, and wind erosion remain unclear. Based on a 20-year grazing experiment (2004-2023) and an 11-year aeolian erosion monitoring program (2013-2023), this study examined four stocking rates: non-grazing control (CK), light (LG), moderate (MG), and heavy grazing (HG). Aeolian sediment was collected using BSNE samplers, and vegetation and climate variables were monitored during growing seasons. Structural Equation Modeling (SEM) revealed a hierarchical response of aeolian sediment flux across interannual variation, stocking rate, and collection height. Two synergistic pathways were identified: "precipitation-* vegetation characteristics-* aeolian sediment flux" and "stocking rate-* vegetation characteristics-* aeolian sediment flux." Precipitation reduced sediment flux in wet years by improving vegetation; stocking rate altered vegetation and modulated sediment flux in normal years; grazing amplified wind erosion in dry years, making wind speed the dominant driver. In conclusion, wind erosion mechanisms in desert steppes vary dynamically with precipitation and grazing intensity. Grazing disturbance is not the sole cause of erosion but interacts with multi-level factors and annual climate conditions. Critically, grazing amplifies erosion during drought years, which may be a key driver of grassland degradation in arid regions.

Context: Climate change exacerbates global precipitation imbalances, with potential impacts on plant diversity in desert steppe ecosystems. Compared with meadow and typical steppes, desert steppe could be more sensitive to changing precipitation. However, experimental evidence on how changing precipitation affects plant diversity is still scarce. Based on this, we designed a study to simulate the effects of precipitation on plant diversity in the desert steppe so as to provide theoretical support for the reasonable management, sustainable development and utilization of the desert steppe. Objective: We investigated plant diversity and soil moisture under simulated precipitation to quantify and analyze the effects of precipitation on these variables in the desert steppe. Methods: We established four precipitation treatments in the desert steppe: precipitation reduced by 50 % (P1), ambient precipitation (Control, P2), precipitation increased by 50 % (P3), and precipitation increased by 100 % (P4). We monitored the plant richness, and soil moisture from 2016 to 2018, from May through October. Results and conclusions: The results showed that: (1) Soil moisture in the P4 treatment increased 127.8 % in 2018 at the 30-40 cm layer, while P3 only increased shallow soil moisture (36.5 % at 0-10 cm). (2) Reduced precipitation significantly decreased plant species richness by 59.7 % and 42.8 % in 2017 and 2018, respectively, while increased precipitation (P3 and P4) did not significantly enhance richness. (3) Species richness showed a significant positive correlation with soil moisture at 0-10 cm in P3 and P4 , the relationship between soil moisture and plant species richness is significantly influenced by precipitation treatment and soil depth. The promoting effect of shallow soil moisture on species richness is more prominent under conditions of increased precipitation. These findings demonstrate that desert steppe biodiversity is highly sensitive to reduced precipitation and shallow soil moisture depletion. Enhancing surface soil moisture retention-through water-conserving vegetation or microtopography management-could be an effective strategy to buffer biodiversity loss under increasing climatic variability.

Although numerous studies have shown that grazing gives rise to community succession from the communities or even species perspective, there is a lack of discussion about how grazing drives community assembly based on plant functional traits in a long-term experiment. We find different grazing intensities lead to temporal effects on trait-mediated multidimensional community assembly processes, including community-weighted trait mean (CWM), trait filtering, and trait distribution (divergence/convergence). CWM, trait filtering, and trait distribution of different traits transformed over the 16-year grazing experiment. Major findings include the following: (1) CWM changed rapidly under higher grazing intensity, and the removal of unsuitable traits from communities over time was accelerated with higher grazing intensity, such as higher specific leaf area (SLA), rich epidermal appendages (PAP), deep root system (RD), and growth form (shrub and subshrub) and dispersal mode (DM, e.g., insect spread) with higher scores. (2) Patterns of trait filtering strongly depended on grazing intensity and trait types, most traits, such as SLA, DM, PAP, RD, and onset of flowering (OFL), were filtered at high grazing intensity area, and effects of trait filtering in the community assembly process strengthened with grazing time. (3) Traits related to the cycling of biological matter, such as leaf area (LA), SLA, reproductive height (RH), photosynthetic (PHO), and GF more frequently diverged after long-term grazing, especially in higher grazing areas. Community assembly in intensely grazed ecosystems takes over a decade to support fundamental functions, highlighting the need for grazing intensity thresholds for sustainable grassland use.

Plant microbiome plays a vital role in plant fitness and ecosystem functioning, yet its response to global environmental change remains poorly understood. Using an 18-year field experiment, we investigated the effects of climate warming and nitrogen deposition on the diversity of leaf epiphytic and endophytic bacterial communities in two dominant plant species (Stipa breviflora and Cleistogenes songorica) of a temperate desert steppe. We found that warming and nitrogen addition increased both epiphytic and endophytic bacterial diversity, but via different mechanisms. Specifically, epiphytic diversity increased with leaf temperature and transpiration rate, whereas greater endophyte diversity was linked to higher leaf carbon and nitrogen concentrations. Structural equation modeling revealed that both epiphytic and endophytic diversity were negatively associated with plant diversity. Our results demonstrate different mechanisms driving similar responses of leaf epiphytic and endophytic bacterial diversity to global change, and point to a negative feedback loop between phyllosphere bacterial and plant diversity.

Understanding biomass allocation patterns is critical for predicting plant adaptation strategies under climate change scenarios. At present, the theory of biomass allocation (optimal allocation and equidistant allocation) is still controversial, especially in the “fragile” desert steppe, which is especially sensitive to climate change. Therefore, we set up four treatments with varying precipitation gradients [natural precipitation reduced by 50 % (W-50 %), control (WCK), natural precipitation increased by 50 % (W+50 %), and natural precipitation increased by 100 % (W+100 %)] in the desert steppe of Inner Mongolia and applied them for six years before analyzing the trade-off relationship between aboveground and below-ground biomass, verifying the distribution theory, and considering the factors affecting change in biomass distribution. Our findings revealed that the aboveground biomass increased significantly with the increase of precipitation gradient, while the below-ground biomass was significantly different between years. Desert steppe plants allocated more biomass to the below-ground and followed the optimal allocation theory, W-50 % amplified the trade-off of biomass to the belowground, W+50 % and W+100 % treatments transferred the biomass aboveground instead, which claimed that both plant diversity and soil physicochemical properties regulate biomass allocation. At W-50 % treatment, plant growth was limited by soil water content. At W+50 % and W+100 % treatments, plants were limited by soil available nutrients. The “opportunistic” strategy of annual herbs explains why biomass was re-directed to the aboveground organs. Our results emphasize desert plants can adapt to precipitation change using high variation and optimal biomass allocation.

Precipitation significantly influences the composition and structure of grassland ecosystems, particularly in arid desert steppes. Stipa breviflora, as a keystone species, plays a crucial role in maintaining the stability of the desert steppe. However, the response of S. breviflora's succession strategy to changes in precipitation within the community remains uncertain. Since 2016, this research was conducted in a desert steppe in Inner Mongolia, China, involving control precipitation (PCK), and increases of 50% (P50) and 100% (P100) in natural precipitation. We measured biomass, height and canopy cover, calculated the importance value (IV) by species, and assessed the photosynthetic parameters and leaf elemental content of S. breviflora in 2021 and 2022. Results showed that the increase of precipitation significantly reduced the IV of S. breviflora. The net photosynthetic rate, transpiration rate, stomatal conductance, aboveground biomass carbon content and aboveground biomass nitrogen of S. breviflora leaves grew considerably in experimental plots receiving more precipitation, while delta 13C value of leaves decreased significantly. Linear regression analysis and structural equation model showed that although the increase of precipitation improved the adaptability of S. breviflora functional traits and increased its IV, a higher transpiration rate significantly contributed to the decrease in its IV. Consequently, our research reveals the succession strategy of S. breviflora and provides a theoretical basis for studying the response mechanisms of desert steppe plant communities to climate change. (sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(Stipa breviflora)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic),(sic)(sic)(sic)2016(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(PCK),(sic)(sic)50% (P50)(sic)(sic)(sic)100% (P100)(sic)(sic).(sic)2021(sic)2022(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic);(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),delta C-13(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

We aimed to investigate how heavy grazing influences the population dynamics of Stipa breviflora with a specific focus on changes in density and spatial distribution. We measured Stipa breviflora density, basal diameter, and distance between plants in each quadrat and found: (1) The density of Stipa breviflora under no grazing was 56.05 % lower than that under heavy grazing(P < 0.05); (2) No significant difference was showed on the total basal area of Stipa breviflora between heavy grazing and no grazing treatments, but the average basal area of individuals heavy grazing was 51.32 % lower than no grazing (P < 0.05). (3) The euclidean distance between individuals, and the number of seedlings were both 4.04 % and 78.79 % under heavy grazing lower than no grazing, respectively. Overall, we suggest that the increased density of Stipa breviflora under heavy grazing was caused by fragmentation.

Grazing by livestock can influence the diversity and productivity of plants in an ecosystem, as well as the relationship between productivity and diversity. Furthermore, these effects or their relationship can be strongly influenced by variation in the intensity of grazing as well as external environmental conditions, such as rainfall amount. We used observations over an 18-year period in a desert steppe grassland in Inner Mongolia to evaluate how different intensities of grazing influenced productivity, diversity and the underlying mechanism of their relationship through time. Increasing intensity of grazing led to decreased species richness, primarily via the loss of subordinate and rare species, and a decrease in aboveground net primary productivity [ANPP: g m-2], primarily due to a reduction in dominant species (especially the forb species, A. frigida). We found a positive association between diversity and productivity in most experimental years (14 out of 18 years), with the slope being strongest in wetter years. This suggests that their positive relationship may be affected by precipitation. We used a random forest model to show that variation in ANPP was mainly driven by variation in dominant species, not species richness. Dominant species may be the key driver in regulating plant primary productivity in these species-poor, water-limited grassland ecosystems, and that less intense grazing may be an appropriate management regime to balance ecosystem functions and herder's income.

While grazing effects on soil organic carbon (SOC) stocks are documented, how stocking rates repartition carbon between labile and stable fractions in desert steppes remains unknown. Previous studies have focused predominantly on individual carbon pool stocks rather than on inter-component equilibrium. Here, we evaluated the results of a twenty-year controlled grazing experiment, systematically analyzing how prolonged stocking pressure alters the proportional stability of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) by disrupting the formation of POC and MAOC from plant and microbial precursors. We found that, despite maintaining stable proportions relative to total SOC, POC and MAOC sub-pools exhibited parallel declines under overgrazing. This demonstrates that SOC destabilization arises from systemic changes to carbon repartitioning rather than from isolated pool depletion. Grazing-induced shifts in plant community composition and soil structural features impaired microbial functionality and enzymatic processes, limiting the transformation of organic substrates into more stable forms of soil carbon. These findings advance desert steppe management by highlighting the importance of prioritizing component ratio stability over conventional stock-based metrics and offers actionable strategies to balance carbon sequestration.

Accurate assessments of the utilization rate of rangeland are crucial for research on carbon dynamics, biodiversity conservation, and effective grassland management. Traditionally, utilization intensity has been measured based on the number of grazing livestock, without accounting for variations in grassland productivity. The use of this conventional approach has limited applicability for large-scale monitoring purposes, especially in terms of capturing regional variability and intra-annual utilization changes. The utilization rate of the rangeland (UR) metric provides a more comprehensive view and reflects the direct impact of management practices on ecosystems. As an essential indicator of grazing intensity, UR facilitates a deeper understanding of how grazing affects ecosystem responses, supporting more effective monitoring and management of grassland. Remote sensing technology has emerged as a promising tool for generating up-to-date, large-scale UR inventories; however, the potential of remote sensing for accurate UR monitor remains underexplored, partly due to the difficulty of capturing clear signals from grassland under active grazing. This study systematically evaluated the ability of remote sensing data to monitor UR, leveraging aboveground biomass (AGB) measurements and time series data from harmonized Landsat 7/8/9 and Sentinel-2 imagery. Based on a long-term grazing experimental platform across diverse grassland types, we explored the correlation between remote sensing characteristics and UR dynamics to identify the optimal dataset for high-precision UR monitoring in different grassland environments. Our methodology involved two key steps: first, we analyzed the relationship between changes in remote sensing features and UR variations, selecting the optimal indicators for monitoring UR across different grassland types. Second, we evaluated the predictive performance of parametric models (linear mixed effect model and generalized additive model) and nonparametric models (eXtreme Gradient Boosting and support vector machine) for UR estimation. These models were chosen for their outstanding ability to deal with small-size sample scenes. Each model was assessed in terms of its accuracy, temporal stability, and spatial consistency. Among the studied models, the support vector machine algorithm achieved the highest predictive accuracy (R-2=0.90) and temporal-spatial robustness, as confirmed by K-fold cross-validation (fn(Xn)=0.70). In all grassland types, this model exhibits good stability and performs well on small samples. The model is minimally affected by differences between sampling dates and satellite data acquisition dates. Overall, the results of this study indicate that (1) the remote sensing indicators significantly correlated with UR vary across grazing platforms, with no single indicator universally suitable for all grassland types, (2) the support vector machine model can achieve high accuracy for UR estimation, and (3) the proposed UR remote sensing model exhibits strong temporal and spatial stability. This research highlights the feasibility of utilizing remote sensing data for large-scale UR monitoring, providing a scientific foundation for enhancing grassland grazing management and supporting ecological restoration efforts, such as assessing the impact of grazing on production, climate, ecosystem service, soil, and the carbon cycle.

Grazing is a primary use of natural grasslands. Grazing livestock plays a crucial role in grassland ecosystems, and livestock behavior is a key factor affecting the structure and function of grassland ecosystems. Reasonable grazing intensity can regulate livestock behavior, promoting the sustainable use of grassland resources. The desert steppe, a transitional ecosystem between grasslands and deserts, is an important and unique part of the Eurasian temperate steppe. The desert steppe plays an important role in carbon sequestration, biodiversity, animal husbandry and regional economic development. However, current research on livestock behavior in desert steppes is limited, and the effects of different grazing intensities on this behavior and diet selection are not well understood, and the rational grazing utilization intensities need to be further clarified. In this study, a long-term grazing experiment with four grazing intensities (control, 0 sheep unit hm-2 half a year-1; light grazing, 0.91 sheep units hm-2 half a year-1; medium grazing, 1.82 sheep units hm-2 half a year-1; heavy grazing, 2.71 sheep units hm-2 half a year-1) was established in the Stipa breviflora desert steppe in Nei Mongol in China. The changes in sheep behavior and diet selection under different grazing intensities were analyzed and rational grazing intensity was explored. The results show that: (1) As for sheep behavior, the foraging and traveling time were increased but lying time was decreased under moderate and heavy grazing treatments as compared with light grazing. Livestock activity and distance also significantly increased under moderate and heavy grazing. Livestock grazing behavior varied with seasons, and the feeding and traveling time of sheep was significantly longer at the end of the growing season than that at the peak of growing season. (2) With the increase in grazing intensity, the aboveground biomass of plants and the diversity of feeding components of sheep decreased significantly. The preference of the sheep for the perennial grasses Stipa breviflora and Cleistogenes songorica increased, but the selectivity of the shrub Caragana stenophylla decreased gradually. Furthermore, livestock diet selection varied with seasons, especially, the selective feeding of Stipa breviflora reached the highest at the end of the growing season. (3) Sheep's body weight gain correlated with grazing behavior. Longer foraging and traveling times resulted in higher feed intake but lower digestibility and daily weight gain. Light grazing allowed for shorter foraging and traveling times, lower feed intake, higher digestibility, and better plant resource availability, benefiting both livestock performance and grassland productivity and diversity. Therefore, the study concludes that light grazing is a reasonable intensity for achieving long-term sustainable use of the desert steppe. It contributes to the understanding of grassland grazing livestock research, provides theoretical support for optimizing grassland primary and secondary productivity, and offers crucial insights for improving desert steppe grazing management and ensuring sustainable grassland use.

Climate change is known to affect plant phenology. Yet, the sensitivity of flowering phenology in dryland regions to climate change, and the potential implications for community composition, remain largely unexplored. Here, we used an 18-year field experiment to investigate the effects of climate warming and nitrogen addition on flowering phenology of four C3 plant species and two C4 plant species, and the cascading effects on the relative abundance of C3 and C4 plants in a desert steppe. Across the past 10 years of the experiment (2013-2022), we found that warming had a greater effect on phenological shifts in C3 than in C4 plants. Warming significantly advanced the flowering time of C3 plants by 4.3 ± 0.1 days and of C4 plants by 2.8 ± 0.1 days, respectively. Warming also reduced the duration of flowering by 1.8 ± 0.1 days for C3 plants but had no effect on C4 plants, and decreased the dominance of C3 plants compared to C4 plants. Nitrogen addition extended the duration of flowering of C4 plants by 3.4 ± 0.2 days and increased their relative dominance, while decreasing the dominance of C3 plants. Structural equation models revealed that these phenological responses were largely driven by soil temperature and soil water availability. Our results demonstrate that the different phenological responses of C3 and C4 plants contribute to shifts in dominance between these plant types in temperate dryland ecosystems under global changes.