Phytolith-occluded organic carbon （PhytOC）， which is a part of the organic carbon encapsulated during the silicification process in grassland plants， constitutes an important component of the grassland carbon sink. The sequestration of PhytOC is important for maintaining the dynamic balance of the carbon cycle within grassland ecosystems. However， the sequestration of PhytOC in grassland ecosystems has not received enough attention and remains insufficiently studied. In this study， we reviewed the current research progress on terrestrial ecosystem PhytOC， analyzed the formation and sequestration of plant PhytOC， the accumulation and stability of soil PhytOC， and the distribution and storage of PhytOC across different grassland types. We also discussed the impacts of human activities and global climate change on grassland PhytOC. Furthermore， the future research directions for PhytOC in grassland ecosystems were also proposed. An in-depth study of PhytOC in grassland ecosystems can provide a theoretical basis for accurately estimating the carbon sequestration potential of phytolith under the background of global climate change， and this could further enhance the carbon cycle model of ecosystems.

Grassland ecosystems， as one of the dominant types of terrestrial ecosystems worldwide， exhibit substantial carbon sequestration potential and play a vital regulatory role in the global carbon cycling and climate change mitigation. This article conducted a bibliometric and visualization analysis of 4，464 publications in the Web of Science Core Collection （WOS） and China National Knowledge Infrastructure （CNKI） database spanning from 1999 to 2022 by VOSviewer and CiteSpace. Current research status and development trends on carbon sequestration functions in grassland ecosystems were examined. The results revealed an increase trend in publication outputs on the carbon sequestration function of grassland ecosystems. Country distribution analysis of publications in WOS database by VOSviewer identified that China and the United States lead this research area. Institute analysis of publication by CiteSpace indicated that Chinese Academy of Sciences， the United States Department of Agriculture， and the University of the Chinese Academy of Sciences emerged as the top three in WOS database. Northwest A&F University， the University of the Chinese Academy of Sciences， and Beijing Forestry University were the most active institutes in the CNKI database. However， there is still potential for improving effective international communication and collaboration among nations and research teams. The bibliometric analysis identified three research hotspots in this field： the driving effects of climate change， human activities， and soil microbial communities on dynamics of carbon sequestration functions in grassland ecosystems；the spatiotemporal variation characteristics of soil carbon storage； and the evaluation of carbon sequestration functions in grassland ecosystems.

Elytrigia elongata is a kind of perennial forage and ecological grass with saline-alkali tolerance， high yield and good quality， which plays an important role in the improvement of saline-alkali land and ecological environment construction in coastal areas in China. However， its biotechnology system is still immature. In this study， 8 germplasm from different sources of Elytrigia elongata were used as experimental materials， tissue culture technology was used to construct the young embryo regeneration system， and excellent acceptor materials suitable for constructing genetic transformation system were screened. The results showed that on the modified induction medium （MS medium+0.5 g/L L-glutamic acid+0.5 g/L L-proline+0.3 g/L enzymatically hydrolyzed casein+30 g/L maltose+2 mg/L 2，4-D+7 g/L AGAR）， a smaller callus was formed on the third day of Elytrigia elongata germplasm culture， and differentiation occurred after 4 weeks of culture. The callus induction rate， differentiation rate， and regeneration time of young embryo of different genotypes were significantly different on the same medium. Among them， the callus induction rate of young embryos of germplasm No.4 was as high as 97.92%， the differentiation rate was 88.33%， the rooting rate was 100.00%， and the regeneration time was relatively short （56.2 d）， which could be used as an ideal chassis material for genetic transformation of Elytrigia elongata.

Heat shock transcription factor （HSF）， widely found in eukaryotes， are one of the most crucial transcriptional factors families in the plant resistance to heat stress. HSF has highly conserved DNA-binding domain （DBD）， which is involved in complex stress signal transduction and response networks. HSF， as a terminal component of the signal transduction chain， mediated the expression of target genes under abiotic stress. In response to stress， HSF is phosphorylated and ubiquitinated by upstream protein kinases or binds to heat shock elements （HSEs） through ABA signaling pathway to regulate the expression of downstream genes such as heat shock proteins （HSPs）， thereby improving plant stress resistance. In this study， the discovery， structure， classification， regulatory mechanism of HSF and its role in plant response to abiotic stress （extreme temperature， drought， high salinity， heavy metal， et al.） were reviewed， and the future research direction was expected to provide theoretical basis and gene resources for the genetic improvement of crop and forage stress resistance.

Against the backdrop of China’s “dual-carbon” strategy and the advancement of ecological civilization， scientific assessment of the ecosystem service values and the realization of ecological product value have becomeacritical approach to harmonize ecological protection and economic development. As the dominant type of grassland ecosystem in China， temperate grasslands play crucial roles in carbon sequestration， water conservation， wind erosion control， and biodiversity maintenance. This article systematically reviews the research progress and methodological framework in economic valuation of temperate grassland ecosystem services， both in China and internationally. The applicability and limitations of major models were compared， and deficiencies in current Chinese research regarding data precision， parameter localization， service coverage， and policy integration were analyzed. This review proposes that future research should focus on constructing multi-scale integrated assessment frameworks， improving model localization and data sharing mechanisms， and strengthening the integration between assessment results and policies such as ecological compensation， GEP accounting， carbon trading， etc.， thereby forming the closed-loop mechanism of “Assessment-Accounting-Compensation-Feedback”. This study aims to provide theoretical foundation and decision support for valuing temperate grassland ecosystem services and realizing the value of ecological products.

Fertilization is a key strategy for restoring degraded grasslands. To identify suitable nitrogen （N） and phosphorus （P） fertilization gradients for enhancing the productivity and soil characteristics of degraded alpine meadows， a lightly degraded alpine meadow in Dangxiong County， Xizang Autonomous Region， was selected for study. A two-factor randomized block design was employed， with four nitrogen levels （N0：0 kg N/hm²， N1：60 kg N/hm²， N2：90 kg N/hm²， N3：120 kg N/hm²） and four phosphorus levels （P0：0 kg P₂O₅/hm²， P1：30 kg P₂O₅/hm²， P2：60 kg P₂O₅/hm²， P3：90 kg P₂O₅/hm²）， resulting in 16 N-P treatments combinations， with N0P0 treatment serving as the control （CK）. Grassland productivity and soil characteristics were evaluated to determine the optimal N-P combinations. The results showed that the combined application of nitrogen and phosphorus fertilizers significantly enhanced aboveground biomass compared with the control， with the N2P2 and N2P3 treatments increasing biomass by 136.9% and 111.9%， respectively （P<0.05）. The combined application also improved soil organic carbon content， particularly in the 0-10 cm soil layer， where the N2P1 and N2P3 treatments reached 15.67 g/kg and 15.26 g/kg， respectively. Available phosphorus content was highest under N2P3 treatment in both 0-10 cm and 10-20 cm soil layers， while total nitrogen content was greatest under N3P1 treatment. Grey correlation analysis of aboveground biomass and soil characteristics （0-10 cm） indicated that N2P3 treatment provided the most favorable comprehensive improvement in productivity and soil nutrient status， followed by N3P3 treatment. Therefore， the combination of 90-120 kg/hm² nitrogen fertilizer with 90 kg/hm² phosphorus fertilizer is recommended as the optimal strategy for the restoration of degraded alpine meadows in Dangxiong County， Xizang Autonomous Region.

Overgrazing will destroy grassland， aggravate vegetation degradation， and induce soil wind erosion. In this study， wind erosion monitoring was conducted on Stipabreviflora desert steppe under different grazing intensity （CK: control， LG: light grazing， MG: moderate grazing， HG: heavy grazing）. Plant community coverage was also measured to explore the patterns of aeolian sediment flux at sand collection height of 0-120 cm aboveground and its relationship with vegetation under different grazing intensities. The results showed that during the growing season of Stipa breviflora desert steppe： (1) Under different grazing intensities， the plant community coverage from May to October demonstrated the pattern of CK>LG>MG>HG. Under the same grazing intensity， it initially increased then decreased. (2) With the increase of grazing intensity， the total aeolian sediment flux rose gradually， with the value under LG， MG and HG reaching 1.40， 1.82， and 1.95 times of that under CK， respectively. (3) There was a significant negative correlation between plant community coverage and total aeolian sediment flux across all grazing intensities （P<0.05）. (4) The functional relationship among grazing intensity （G）， plant community coverage （C）， and total aeolian sediment flux （Q） was constructed： Q=（0.003 5G²－0.020 2G－0.032 7） C+（-0.251 2G²+1.478G+2.463 6）. The goodness of fit （R²） of plant community coverage and total aeolian sediment flux in CK， LG and MG was greater than 0.9， indicating high goodness-of-fit， while R² of HG was only 0.54， which offers a more integrated solution by striking a viable balance between aeolian sediment flux reduction and herder livelihood needs.Despite ideal windbreak and sand fixation performance of the CK and LG treatments， the MG treatment integrated the requirement of grassland ecosystem multifunctional role on aeolian sediment flux bloking and livelihood needs of herdsmen. This finding provides a scientific basis for exploring ecological protection and resource utilization in desert steppe， and has important practical value for establishing a sustainable and coordinated human-land grassland management framework.

Nitrogenase is the key enzyme driving the natural nitrogen cycle， as it catalyzes the conversion of inert dinitrogen （N₂） into bioavailable ammonia （NH₃）. The most extensively studied nitrogenases， molybdenum nitrogenase （Mo-nitrogenase） and vanadium nitrogenase （V-nitrogenase）， differ significantly in their structure， catalytic properties， and environmental responses. Structurally， V-nitrogenase contains a unique δ subunit and has distinct encoding genes compared to Mo-nitrogenase. For catalytic mechanisms， Mo-nitrogenase exhibits higher specificity for N₂ reduction， whereas V-nitrogenase demonstrates broader substrate range and reduces alternative substrates such as acetylene. Furthermore， the two enzymes exhibit different sensitivity to carbon monoxide （CO）： Mo-nitrogenase is easily inhibited by CO， while V-nitrogenase can reduce CO even under high concentrations. These differences shape their functional performance in diverse environments. By systematically illustrating the structural， catalytic， and environmental differences between these nitrogenases， this study deepens the understanding of dynamic biological nitrogen fixation. The findings provide a critical theoretical basis for optimizing nitrogen management in grassland agriculture and offer guidance for the restoration of degraded ecosystems， such as grasslands， forests， and deserts.

As a fundamental component of regional water resource planning and management， reference evapotranspiration （ET₀） requires a thorough investigation into the time-lag effects and synergistic interactions of different environmental variables for a comprehensive understanding. However， the response time of ET₀ to vapor pressure deficit （VPD） and temperature and their influencing factors remains unclear. In this study， time-lag effects and their interactions for VPD， temperature （including maximum， minimum， and mean temperatures）， Normalized Difference Vegetation Index （NDVI） on ET₀ were analyzed using data from 107 meteorological sites across Inner Mongolia during 2000—2020. The results indicated： ET₀， VPD， temperature， and NDVI exhibited increasing trends over the study period. Notably， the time lag of ET₀ in response to VPD was longer compared to air temperature， particularly for minimum temperatures in high-altitude regions. ET₀ exhibited a stronger potential sensitivity to VPD compared to mean temperature， whereas the response to extreme low temperatures exceeded that to maximum temperature and VPD. an increase in NDVI was found to shorten the lag time of ET₀ in response to air temperature， whereas it prolonged the lag time of ET₀ in response to vapor pressure deficit.

In this experiment， 14 bermudagrass germplasms were used as materials. Agronomic traits （erect stem diameter， stolon diameter， stolon internode length， stolon length， branch number， reproductive branch number， leaf width， leaf length， leaf color， grass layer height， reproductive branch height， inflorescence number， inflorescence length， spikelet number， 1000-grain weight， seed length， seed width）， turf quality index （color， texture， density， uniformity， drought resistance， heat resistance ） and growth and regeneration performance indices （stolon and erect stem growth rate， regeneration rate） were evaluated. The results showed that： （1） there were significant differences among 14 germplasms， except for erect stem diameter and stolon diameter. The variation coefficient of 17 agronomic traits ranged from 7.88% to 36.28%， and the variation of leaves and stems was higher than that of inflorescence and seeds. The turf quality scores of 14 germplasms ranged from 4.97 to 6.85， among which C28， C63 and C121 had higher turf quality. From June to September， the growth rate of 14 bermudagrass erect stems was 0.08-0.31 cm/d， the growth rate of stolons was 0.16-0.43 cm/d， and the regeneration rate was 0.07-0.33 cm/d. Among them， the growth rate of germplasm C22 was the fastest， and the regeneration ability of C72 was the strongest. （2） Based on the height of grass layer， leaf length and reproductive branch height with great variability， combined with turf quality， growth and regeneration rate， the tested germplasms were divided into three categories. The first category included germplasm C72， C28 and C22， which had higher plants， wider and longer leaves， faster growth rate， and were suitable for grazing or soil and water restoration. The second category included germplasm C121 and C63， which were low in plant height， slow growth and regeneration， and suitable for turf use. The third category contained the remaining 9 germplasms with intermediate traits.

Shrub encroachment， which significantly alters structure and function of grassland ecosystems， is a critical ecological issue in China. To obtain a comprehensive and quantitative understanding of the research trends on shrub encroachment research in China， this study conducted a bibliometric analysis using CiteSpace and a meta-analysis based on published literatures on shrub encroachment in China since 1970s. Research on shrub encroachment in China had developed rapidly in recent years， with a primary focus on the drivers of shrub encroachment and its impacts on soil， vegetation， and biodiversity. Studies on shrub encroachment in China had been predominantly conducted in drylands and alpine regions. Major drivers of shrub encroachment included grazing management， climate change， habitat characteristics， and fire. Shrub encroachment was found to have a negative impact on soil quality but a positive effect on community composition， as well as the structure of vegetation and microbial communities in China. The primary management techniques for shrub encroachment included grazing exclusion， grazing management， physical removal， and prescribed burning. This study provides scientific insight into the drivers， impact， and future management strategies for shrub encroachment in Chinese grassland. In the future， it is necessary to strengthen large-scale dynamic assessments of shrub encroachment across diverse grassland types， and integrate remote sensing technology to enhance the scientificity and effectiveness of monitoring and management of encroached landscape in China.

In this study， alfalfa （Medicago sativa cv. Zhongmu No.1） was used as experimental material under mixed saline-alkali stress at concentrations of 0， 40， and 80 mmol/L （NaCl， Na2SO4， Na2CO3 and NaHCO3 molar ratios of 1∶1∶1∶1， pH 9.3）. The growth indexes， physiological indexes and the expression levels of key genes of the seedlings were measured， which provided a theoretical basis for revealing the mechanism of response to mixed saline-alkali stress. The results showed that the plant height， photosynthetic rate， effective quantum yield of PSⅡ photochemistry and the maximum quantum efficiency of PSⅡ photochemistry （Fv/Fm） in ‘Zhongmu No.1’ alfalfa seedlings were significantly inhibited with the intensification of mixed saline-alkali stress （P<0.05）. The accumulation of hydrogen peroxide， superoxide anion， and malondialdehyde gradually increased， while the activity of peroxidase， proline， and soluble sugar content all significantly increased （P<0.05）. Under 80 mmol/L mixed saline-alkali stress， the expression levels of Na+ transporter encoding genes MsSOS1， MsNHX1， and MsHKT1 were significantly induced （P<0.05）. In summary， ‘Zhongmu No.1’ alfalfa may mainly respond to mixed saline-alkali stress through the following pathways： （1） high expression of Na+ transporter genes such as MsSOS1， MsNHX1， and MsHKT1， promoting Na+ efflux， vacuolar segregation and transfer， and avoiding ion toxicity to plants caused by excessive accumulation of Na+； （2） enhance antioxidase activity and alleviate oxidative damage caused by high pH value.

Setaria viridis （L.） P. Beauv， a widely adaptable herbaceous plant distributed throughout China， possesses significant ecological and forage value. Due to its notable stress tolerance and its role as an important model plant， Setaria viridis has attracted wide interest in recent years. This article reviews research findings on the biological characteristics， genetic diversity， ecological value， and cultivar development of Setaria viridis， and offers perspectives for further research. It will provide theoretical references for the development， utilization， and breeding of new Setaria viridis varieties.

This study investigated the effects of varying soil salinity levels on the growth and salt transport capacity of Suaeda salsa （L.） Pall. S. salsa was selected as the test species， and a barrel planting experiment was conducted with six salinity treatments： 10.21 g/kg （S1）， 20.92 g/kg （S2）， 30.29 g/kg （S3）， 40.55 g/kg （S4）， 50.36 g/kg （S5）， and a control treatment （CK） with 6.20 g/kg soil salt content. Plant growth parameters and salt transport capacity were assessed at four growth stages to identify optimal salinity conditions for S. salsa cultivation and ecological restoration in saline soils. The results showed that across all growth stages， the treatment with 20.92 g/kg soil salinity （S2） resulted in the most favorable growth performance for S. salsa， as evidenced by significantly higher plant height， stem diameter， fresh weight， and dry weight compared to other treatments. Specifically， at maturity stage， these parameters increased by 29.87%， 47.75%， 33.54%， and 19.45%， respectively， in the S2 treatment compared to CK. Increased soil salinity generally promoted stem and leaf succulence throughout the adult plant， flowering， and mature stages. Across treatments， a trend of decreasing succulence was observed from the seedling stage to the mature stage. Leaf tissue exhibited the highest salt transfer amount across all treatments， followed by stem and seed. As plants progressed through the growth stages， the ash content in all treatments decreased， likely due to dilution by increasing biomass. However， salt transfer amount continuously increased， reaching a peak at the mature stage. The S2 treatment displayed the greatest salt transfer amount （4250.41 kg/hm²）. These findings suggest that a soil salinity level of 20.92 g/kg promotes optimal plant growth status and salt transfer ability in S. salsa.

In this experiment， 13 quantitative traits and 7 qualitative traits of Caucasian clover （Trifolium ambiguum Bieb.） as the maternal parent， white clover （T. repens L.） as the paternal parent， and 8 F₁ generations bred from distant hybridization between them were investigated， to study the phenotypic relative heritability and heterosis of F₁ hybrids. The results showed that the phenotypic genetic diversity of 13 quantitative traits was abundant， and the coefficient of variation of 11 traits was more than 10%. The genetic diversity index of 7 quality traits was low. The phenotypic inheritance of the F₁ was mostly positively dominant， and the highest relative heritability a₁ can reach 1.92. The relative heritability of female parent to F₁ was higher than that of male parent. The most obvious heterosis of F₁ was the number of florets and fruited florets， and the heterosis rates of 65.03% and 80.96%. Cluster analysis showed that 8 F₁ generations were close to Caucasian clover and far from white clover.

To explore the optimal legume-grass sowing ratio for synergistically improving yield and quality, a two-year field experiment with multiple mowings was conducted on the Loess Plateau. Five sowing patterns of white clover (Trifolium repens) and tall fescue (Festuca arundinacea) were evaluated, including monocultures of each species and mixtures at legume-to-grass ratios of 1:1, 1:2, and 1:3. The study aimed to assess the seasonal dynamics of forage yield and nutritional quality under different patterns and to identify the optimal strategy using a coupling coordination degree model. The results indicated that mixed sowing exhibited significant overyielding effects. Specifically, the mixtures with 1:2 and 1:3 ratios achieved the highest total yields, which were significantly increased by 23.92%-62.71% compared to monocultures (P<0.05). Regarding quality, compared with the monoculture of tall fescue, mixed sowing effectively increased crude protein content and reduced fiber content. The coupling coordination degree analysis of yield and quality demonstrated that the 1:2 legume-grass ratio is the optimal pattern for achieving synergistic development. This pattern not only achieved synchronous optimization in yield and quality but also maintained a high-level coordination state throughout the growing season. Consequently, it extends the window period for optimal utilization, making it the ideal strategy for establishing high-yielding, high-quality, and stable grasslands.

Nutrient enrichment is a key driver of plant diversity loss in grassland ecosystems. However， the specific pathways and mechanisms underlying species diversity reduction under different nutrient additions influence remain insufficiently understood. This study investigated the effects of nitrogen （N）， phosphorus （P）， and combined nitrogen and phosphorus （N+P） additions on alpine meadows located on the eastern edge of the Tibetan Plateau， using the natural community as a control. The main objective was to examine changes in species richness， biomass， and light transmission， and to elucidate the direct and indirect mechanisms contributing to species richness decline under these experimental treatments. The results showed as follows：（1） N was identified as the primary limiting nutrient for aboveground biomass. Both N and N+P additions significantly increased aboveground biomass （P<0.05）， primarily due to an increase in the biomass of grasses； （2） N and N+P additions significantly reduced species richness （P<0.05）， whereas P addition alone had no significant effect； （3） The mechanisms underlying the reduction in species richness under N and N+P treatments were consistent and involved both direct effects of nitrogen and indirect effects via increased aboveground biomass， which in turn reduced light availability.

Ecosystem services （ES） and ecological risk （ER） respectively represent the capacity of ecosystems to support human well-being and the potential for degradation under external disturbances. In recent years， the cumulative impacts of glacier retreat， permafrost degradation， and grassland deterioration have led to a decline in ES and an increase in ER on the Qinghai-Xizang Plateau. Therefore， exploring the coupling relationship between ES and ER on the Plateau is of great importance for accurately identifying ecological degradation processes， improving regional ecological resilience， and supporting effective environmental management. Based on remote sensing and statistical data from 2000 to 2020， this study evaluated important ES indicators and constructed an ER assessment framework using the InVEST model and landscape ecological risk assessment methods. The results showed that： （1） From 2000 to 2020， mean annual grassland productivity increased from 91.63 g/m² to 107.52 g/m²， while carbon storage declined from 6 571.73 Mg to 5 897.60 Mg. Water yield decreased from 122.10 mm to 86.55 mm in 2015 and rebounded to 110.71 mm in 2020. Habitat quality declined from 0.51 to 0.45， and soil conservation showed periodic fluctuations， ranging between 33 391.59 g/m² and 25 772.08 g/m². （2） The overall ER level showed a slight decline， but high-risk areas still accounted for over 19%， primarily concentrated in ecologically fragile zones such as Kekexili， the Qiangtang Plateau， and the Qaidam Basin. （3） Correlation analysis revealed significant negative correlations between ER and both grassland productivity （R² = -0.66， P < 0.05） and habitat quality （R² = -0.73， P < 0.05）. Carbon storage， water yield， and soil conservation also exhibited moderate negative correlations， suggesting that ER exerts an overall inhibitory effect on ES.

To evaluate the differences in salt tolerance among new lines of bermudagrass (Cynodon dactylon), identify key indicators for salt tolerance assessment, and thereby facilitate the breeding of new salt-tolerant cultivars, this study used 'Xinnong No. 1' bermudagrass as the control. Three new lines (C_138, C₂₂, C₆₃) were subjected to NaCl stress at concentrations of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% during both seed germination and seedling stages. Germination, growth, and physiological parameters were measured. A comprehensive evaluation of salt tolerance was conducted by integrating the entropy-weighted TOPSIS method, membership function analysis, and the Comprehensive Salt Tolerance Index (CSI). The results indicated that salt stress significantly inhibited seed germination and seedling growth of bermudagrass, with clear differential tolerance observed among the lines. C₁₃₈ demonstrated the best performance across both stages, maintaining relatively high levels of germination rate, vigor index, aboveground biomass, and leaf relative water content under salt stress. C₆₃ performed well under low to moderate salinity (≤1.0%). The entropy-weighted TOPSIS analysis revealed that germination potential and vigor index were major contributing factors during the germination stage, whereas aboveground and belowground biomass were key during the seedling stage. Based on the combined analysis of the membership function and CSI, the salt tolerance of the four bermudagrass materials was consistently ranked (from strongest to weakest) as follows: C₁₃₈, C₆₃, 'Xinnong No. 1' bermudagrass, and C_22. In summary, C₁₃₈ exhibits strong comprehensive salt tolerance and shows promise as an excellent material for saline-alkali land improvement, while C₆₃ is suitable for mildly saline environments. These findings provide a basis for the breeding and promotion of salt-tolerant bermudagrass varieties.

Sandy land ecosystems play a critical role in the global carbon cycle， with their internal carbon cycling mechanisms being key to maintaining the global carbon balance. Soil organic carbon （SOC）， as the core component of this system， not only influences the cycling and turnover rates of soil organic matter but is linked to changes in the functional state of sandy ecosystems. It serves as a key indicator for assessing the health and stability to these systems. To gain a deeper understanding of SOC and its stability characteristics in sandy lands， relevant literature from 1998 and 2024 was compiled from the Web of Science （WOS） and China National Knowledge Infrastructure （CNKI） databases for analysis. The results showed that： （1） From 1998 to 2024， the number of publications on SOC in sandy lands showed an increasing trend. Domestic research hotspots focused on "soil nutrients" and "desertification"， while international hotspots were "nitrogen"，"carbon"， and "land use". （2） SOC content， storage， and its composition in sandy lands are influenced by various factors such as land use patterns， microbial activity， vegetation types， and human activities.（3） The stability of SOC in sandy lands results from the combined effects of physical， chemical， and biological protection. Physical protection （e.g.， aggregates） provides a microenvironment for chemical protection （e.g.， mineral adsorption）， while biological protection （e.g.， microbial activity） promotes aggregate various modern technological approaches to achieve long-term， spatially networked observation. In the future， multiple modern technological means should be integrated to achieve intelligent， networked， multi-scale and three-dimensional long-term positioning observations.It is also essential to develop and apply soil carbon sequestration techniques tailored to local conditions. This will help fully reveal the influencing factors and stabilization mechanisms of SOC in sandy lands， laying the foundation for achieving sustainable carbon sequestration goals in these environments.

To clarify the impact of wind turbines on biodiversity and soil properties of grasslands， this study took a wind power area with wind turbines installed and operated for 15 years in the temperate meadow steppe of Inner Mongolia as the research area， and selected a grassland without wind turbines as the control area. The plant community， insect community， soil microorganisms， and soil physical and chemical properties in the area were investigated， and the relationships among these factors were analyzed. The results showed that compared with the grassland in the control area， the vegetation coverage， aboveground biomass， and community diversity of the grassland in the wind power area decreased significantly （P<0.05）. The number of insects in the wind power area increased significantly （P<0.05）， but the diversity of the insect community decreased significantly （P<0.05）. The number of soil fungi and community diversity in the wind power area were all significantly reduced （P<0.05）.Soil moisture content， bulk density， total nitrogen， ammonium nitrogen， alkali-hydrolyzable nitrogen， total phosphorus， and total potassium in the wind power area were all significantly reduced （P<0.05）. Correlation analysis found that there was a significant relationship between soil physicochemical properties and soil microbial communities. Overall， during the operation period of wind power stations， it will cause the degradation of grassland plant communities， the loss of soil nutrients and reduce plant diversity， and lead to a homogenization of the insect community structure.

To identify suitable forage oat cultivars and determine the optimal cutting stage for saline alkali soils in the Hetao Irrigation District, 14 domestic and foreign forage oat cultivars were evaluated. Differences in yield, forage quality, and digestibility characteristics were analyzed across different growth stages, and comprehensive screening was conducted using grey relational analysis. The results showed that plant height differed significantly among cultivars and growth stages, and all cultivars exhibited an "S" shaped growth curve. In terms of cultivar main effects, fresh forage yield and hay yield ranged from 21 451.67 to 38 916.53 kg/hm² and from 5 620.76 to 8 359.18 kg/hm², respectively. The crude protein (CP) contents of the ‘Leader’ (Souris), ‘Baler’ and ‘Baler No.2’ exceeded 10.00% of dry matter (DM) and were significantly higher than those of other varieties except ‘Yellow oat’. The neutral detergent fiber (NDF) contents of ‘Baler’, ‘Baler No.2’, and ‘Yellow oat’ was significantly lower than those of most other varieties, except ‘Leader’ (Souris). The acid detergent fiber (ADF) contents of ‘Leader’ (Souris), ‘Baler’, and ‘Baler No. 2’ were significantly lower than those of other cultivars, except ‘Yellow oat’, while acid detergent lignin (ADL) content was lowest in ‘Haymaker’, ‘Baler’, and ‘Helios’. ‘Haymaker’ had the highest ether extract (EE) content. Regarding cutting stage, hay yield and dry to fresh ratio followed the order milk stage > flowering stage > heading stage. At the flowering stage, fresh forage yield and water-soluble carbohydrate (WSC) content were highest, while CP, dNDF₃₀, dNDF₄₈, NDFD₃₀, NDFD₄₈, IVTDMD₃₀, and IVTDMD₄₈ were second only to those at the heading stage. ADL content was also significantly lower at flowering than at the milk stage. The relative feed quality (RFQ) values of ‘Haymaker’ and ‘Baler’ were significantly higher than those of all other cultivars except ‘Leader’ (Souris). Gray relational analysis showed that NDF, IVTDMD₄₈, ash, dNDF₃₀, and IVTDMD₃₀ ranked as the top five weighted indicators. Both equal weight and weighted correlation degrees ranked ‘Baler’, ‘Haymaker’, and ‘Leader’ (Souris) among the top three cultivars. In conclusion, NDF was the primary indicator for evaluating the production performance of forage oats in saline alkali soils of the Hetao Irrigation District. ‘Baler’, ‘Haymaker’, and ‘Leader’ (Souris) showed the best overall performance and were suitable for cultivation in this region. The flowering stage provided the best comprehensive production performance and was recommended at the optimal cutting stage.

Soil organic carbon （SOC）， with its critical ecological functions， is a key indicator for assessing the effectiveness of ecological restoration in grassland surface mining areas. This review focused on the effects of ecological restoration on SOC， considering vegetation， soil， and soil microbial restoration. Plant， soil， and soil microorganism all influenced SOC dynamics in grassland surface mine， with soil microorganisms likely playing the most significant role in SOC changes. Additionally， this review identified existing challenges and proposed potential strategies to address issues related to plant， soil， and microbial restoration in these areas. The review also emphasized the importance of investigating the interactive effects between plant， soil， and soil microorganisms on SOC. This review provides theoretical insights to guide the rational implementation of ecological restoration practices and support further research development， technical advancement， and application on this field.

Grassland restoration is a critical pathway toward achieving sustainable utilization and high-quality development goals for degraded ecosystems. While scientific evaluation of restoration outcomes provides essential evidence for optimizing rehabilitation strategies， current methodologies predominantly focus on pre- and post-restoration changes in individual or limited indicators （e.g.， biomass， vegetation coverage）， with insufficient attention to comprehensive multi-indicator assessments. To address this issue， this study used factor analysis to comprehensively evaluate eight restoration approaches and nine ecological restoration effect assessment indicators for degraded grasslands in Chen Barag Banner， Inner Mongolia， aiming to identify representative community assessment indicators and suitable restoration approaches. The findings demonstrated that： （1） Three critical indicators-vegetation coverage， aboveground biomass， and community species richness-were identified as representative metrics for restoration evaluation. （2） The integrated approach combining fencing with root pruning， fertilization， and sustained management practices demonstrated superior restoration effectiveness. Our comprehensive quantitative assessment methodology exhibited both scientific rigor and practical applicability. These findings provide an evidence-based framework for evaluating and managing grassland restoration initiatives in Inner Mongolia's degraded steppes and comparable ecoregions.

In order to improve the forage yield and quality of degraded alfalfa grassland in the semi-arid region of Ningxia， this study was conducted using a single-factor randomized block design to investigate the effects of different diammonium phosphate （DAP） application rates （0， 75， 150， and 225 kg/hm²） on the production performance and forage quality of alfalfa. The results showed that application of DAP significantly increased alfalfa plant height， branch number， and hay yield， while decreasing neutral and acid detergent fiber contents. Among these treatments， 150 kg/hm² fertilization treatment yielded the highest two-year average plant height （79.05 cm）， hay yield （9774.50 kg/hm²）， crude protein yield （2005.31 kg/hm²）， stem phosphorus content （0.20%）， leaf phosphorus content （0.24%）， and phosphorus uptake content （21.57 kg/hm²）. 75 kg/hm² treatment recorded the highest phosphorus use efficiency （PUE）， with a mean PUE of 8.70% across both years. Structural equation model （SEM） revealed highly significant （P<0.001） direct positive effects of plant height on phosphorus content， branch number on hay yield， and hay yield on phosphorus uptake content. The fitted equations predicted that the maximum yield potential of alfalfa was 9789.59 kg/hm² for hay yield and 2005.56 kg/hm² for crude protein when average DAP application rates were 149.54 kg/hm² and 148.55 kg/hm² over the two years. Therefore， the optimum DAP application rate for degraded alfalfa grassland in the semi-arid areas of Ningxia was 150 kg/hm².

Grazing is one of the effective strategies for managing weed dynamics in grassland ecosystems. However， the regulatory mechanisms governing forage production and weed dynamics under grazing disturbance remain poorly understood. Therefore， this study investigates the effects of grazing management on the forage productivity of Bothriochloa bladhii （Retz） S.T. Blake， a perennial grass species， and its relationship with weeds in a cultivated grassland in Lubbock County， Texas， USA. Results indicated that： （1） Grazing enhanced the sensitivity of forage productivity， fibers and CP to weeds. （2） Grazing remarkably decreased the weed coverage （61.9%-81.4%， P<0.05） and species richness （23.2%-49.9%，P<0.01）. The inhibitory effects accumulated over time. Consequently， grazing enhanced the community stability and weed competitiveness of Bothriochloabladhii. （3） Grazing increased the forage equivalent unit of Bothriochloabladhii， and improved its quality. The findings provide a theoretical basis for developing appropriate grazing and weed management strategies for integrated crop-livestock production systems.

Plant rhizosheath is the sheath-like structure tightly adhering to the root surface. The unique physical， chemical， and microbiological characteristics of the rhizosheath contribute to vital environmental and biochemical functions including rhizosphere soil aggregation， formation of soil aggregates， enhanced water and nutrient uptake， promotion of microbial colonization， and drought stress resistance. This review provides comprehensive understanding for the research status about rhizosheath in formation and the function and objectively demonstrates current research hot spot. CiteSpace software and bibliometric methods were conducted to retrieve a total of 2812 publications related to rhizosheath from January 1， 2008， to April 30， 2023 in Web of Science （WOS） Core Collection and China National Knowledge Infrastructure （CNKI） database with key words “Rhizosheath”， “Root hair”，“Root exudate”，‘Root sheath’， ‘Root secretion’， and ‘Root hair’. This review illustrates biological， chemical， and physical interactions determining rhizosheath development and plant absorption of water and nutrient from perspectives of plant rhizosheath formation and function. The review aims to provide guidance for further research on molecular genetic mechanisms of rhizosheath development and the application on crop breeding.

Monitoring and evaluation of ecosystem health in nature reserves is a prerequisite for improving the health management of the reserves. To improve the limitations of traditional field survey means， remote sensing indicators were applied in this research to carry out ecosystem health evaluation of grassland ecosystems in nine national nature reserves located in Inner Mongolia. The ecosystem health evaluation index system was constructed based on the three dimensions of vitality， organization and resilience （VOR） by selecting the ideal reference system. In addition， weights of each indicator in different grassland types were calculated by the Critic weight analysis algorithm， and the grassland ecosystem health evaluation and grading levels （excellent-good-moderate-unhealthy） in Inner Mongolia'National Nature Reserves were distinguished. Finally， differences in ecosystem health among the three main grassland types in the reserves， meadow steppe， typical steppe and wetland steppe， were compared for both 2000-2009 and 2010-2019 time periods. Results showed that： （1） All grassland ecosystems in nine National Nature Reserves in Inner Mongolia were healthy， with 22% as excellent， 44% as good， and 33% as medium. （2） Different grassland ecosystems in reserves were all at healthy levels. However， some of the grassland ecosystems in the reserves were still at a moderate level on the dimension of resilience， lower than expected. Thus， enhanced management and protection at the reserve aspect will be required. （3） The ecosystem health of the grassland ecosystems in the reserves was stable and improving in 2010-2019 period compared to 2000-2009. Evaluation indicator system and results in this study can provide important support for health management in reserves and scientific decision-making.

In this research， effects of three light modes of LED red， blue， and green light spectrum at 23.328 mol/（m²·d） DLI （conventional light with 18 h/6 h， red∶blue∶green=280∶70∶10； continuous light with 24 h/0 h， red∶blue∶green=210∶52.5∶7.5； and alternating light with three light spectra： 24 h/0 h， red∶blue∶green=525∶15； red-green light∶blue light=435∶105； green and blue light∶red light=120∶420） on yield quality， physiological activity， and nitrogen metabolism were determined in an controlled environment plant factory with artificial light. The results demonstrated the adaptability of alfalfa to continuous light. Compared with conventional lighting， healthy morphology and maintained yield were observed in alfalfa under continuous lighting， along with increased soluble sugar and starch content. However， decreases occurred in photosynthetic pigment content， stomatal conductance， and Fv/Fm， without excessive accumulating of H₂O₂ and malondialdehyde. Further data showed that the alternation of red/blue-green light promoted leaf expansion， the alternation of red/green-blue light promoted stem elongation， and the alternation of green/blue-red light shortened the flowering time. In terms of nitrogen metabolism， nitrate nitrogen content was significantly reduced under continuous and green/blue-red light alternation， while ammonium nitrogen content was significantly increased under red/green-blue light alternation. Activity of nitrate reductase was significantly reduced under red/blue-green light alternation， while red/green-blue light alternation significantly reduced nitrite reductase activity. The activity of nitrogen metabolism enzymes was inhibited by continuous and alternating lighting， whereas the content of soluble protein， free amino acids， and crude protein in alfalfa were increased. In summary， continuous lighting and alternating lighting patterns are suitable for the production of alfalfa in plant factory with artificial light.

To provide high-quality strain resources for specialized microbial fertilizer applying in arid regions， strains were isolated with characteristics of nitrogen fixation， phosphorus solubilization， plant hormones secretion， and drought tolerance from plant rhizosphere by selective medium on three plant species from arid areas. 16S rRNA identification was applied for molecular distinguish and effects of growth-promoting was tested by paper germination test. Results of this research revealed 35.1% of 37 strains isolated from three plant rhizospheres had the characteristics of phosphorus solubilization， nitrogen fixation， and plant growth-promoting. The nitrogenase activity of the strains ranged from 17.92 to 169.74 nmol C₂H₄/（h·mL）. The concentration of dissolved inorganic phosphorus ranged from 13.39 to 363.31 μg/mL， while dissolved organic phosphorus ranged from 58.69 to 99.37 μg/mL. Twelve of the strains with better nitrogen fixation and phosphorus solubilization were picked for further testing of plant hormone secretion and drought tolerance. Secreting results demonstrated that 2.86 to 27.60 μg/mL indoleacetic acid was produced by all 12 strains. Meanwhile， zeatin and abscisic acid were produced by most of the strains， with the volume of 1.75 to 7.78 μg/mL and 1.98 to 4.61 μg/mL， respectively. Five superior PGPR strains through phylogenetic analysis were identified： strain YB6 was Bacillus subtilis， HC7 was Microbacterium oxydans. Additionally， strains HL7， HC9， and HC3 were categorized under the genera Achromobacter sp.， Ochrobactrum sp.， and Phyllobacterium sp.， respectively. For the results of germination test on paper， five selected PGPR strains both improved seed germination and alleviated the inhibition of drought stress on seed growth. Notably， strains YB6 and HC9 had the most significant effect on seed germination and growth， indicating their potential as valuable microbial fertilizer resources in arid regions.

Grazing is a primary utilization of grassland ecosystems， where livestock behaviors， specifically feeding， trampling， and excrement deposition， directly or indirectly alter soil physicochemical and biological properties. These alternations， in turn， differentially affect biogeochemical processes within the grassland ecosystem. However， the mechanisms by which these behaviors influence soil greenhouse gas （GHG） emissions remain poorly understood. To address this knowledge gap， this study systematically explored the emission mechanism and key influencing factors of carbon dioxide （CO₂）， methane （CH₄）， and nitrous oxide （N₂O） in grassland soil by analyzing the interactions between major grazing behaviors and soil environmental conditions. The results showed that feeding behavior can alter vegetation biomass and regulate vegetation community structure， thereby modifying exogenous carbon inputs to influencing soil CO₂ emissions. Trampling behavior impacts soil physical structure and microenvironmental conditions， which in turn affect soil aeration and microbial activity， leading to variable effects on soil respiration and associated CH₄ and CO₂ emissions. These effects are closely dependent on grassland type and trampling intensity. In contrast， dung and urine deposition increase nitrogen input to the soil and enhance N₂O emissions， primarily by altering soil chemical properties and microbial dynamics. The characteristics of the excreta， grassland type， and environmental conditions all play important roles in regulating nutrient availability and GHG emission in pastoral systems. These findings elucidate the distinct processes and potential mechanisms through which livestock behaviors affect soil GHG emissions in grassland and provide a theoretical basis for optimizing grazing management to mitigate emissions in pastoral ecosystems.

To investigate salt tolerance in alfalfa （Medicago sativa） germplasm， 30 alfalfa accessions of diverse origins were subjected to salt stress （200 mmol/L NaCl） for 15 days. Responses were evaluated through changes in seedling morphology， photosynthetic parameters， and physiological indices compared to control plants （CK， irrigated with Hoagland nutrient solution）. The results demonstrated that NaCl treatment decreased plant height， leaf area， leaf relative water content， root activity， shoot dry weight， chlorophyll a， chlorophyll b， transpiration rate， stomatal conductance， net photosynthetic rate， intercellular CO₂ concentration， water use efficiency， catalase （CAT） activity， and potassium （K⁺） content relative to CK. Conversely， root dry weight， root-to-shoot ratio， stomatal limitation value， proline content， malondialdehyde （MDA） content， peroxidase （POD） activity， superoxide dismutase （SOD）， sodium （Na⁺） content， and the Na⁺/K⁺ ratio exhibited increases. Regression analysis identified stomatal conductance， root activity， root-to-shoot ratio， and Na⁺ content as critical indicators for salt tolerance evaluation. The clustering analysis based on the comprehensive evaluation value of the membership function shows that the 30 alfalfa accessions were classified into four distinct tolerance categories： high salt-tolerant， moderately salt-tolerant， low salt-tolerant， and salt-sensitive. Accessions 7254 and 7657 exhibited high salt tolerance.

Heat shock transcription factors （HSFs） play crucial roles in plant growth and development， as well as in responses to biotic and abiotic stresses. In this study， we identified the MruHSF gene family in Medicago ruthenica using genomic data and conducted bioinformatic analyses. The expression patterns of MruHSF gene under drought stress were comprehensively analyzed through transcriptomic data and quantitative real-time PCR （qRT-PCR）， preliminarily exploring their potential roles in drought stress responses. The results showed that 27 MruHSF family members， with encoded proteins ranging from 97 to 505 amino acids （aa）， isoelectric points （pI） between 4.64 and 8.72， and molecular weights of 10 998.3 to 55 296.45 Da. Except for three unassigned gene， the remaining MruHSF genes were distributed across eight chromosomes. Phylogenetic analysis classified them into three evolutionary clades. Conserved motif analysis revealed that all MruHSF proteins except MruHSF02， MruHSF03， and MruHSF27 contained Motifs 1， 2， and 4， which were highly conserved in M. ruthenica HSF protein. Additionally， multiple cis-acting elements related to hormone response， light response， and abiotic stress were identified in the promoter regions of MruHSF genes. Expression analysis shows that MruHSF01， MruHSF08， MruHSF13， MruHSF16， and MruHSF22 exhibited significant differential expression under drought stress， suggesting their potential roles in the drought response mechanism of M. ruthenica.

This research was conducted in the Stipa breviflora desert steppe of Siziwang Banner， Inner Mongolia. We established four stocking-rate treatments 0， 0.91， 1.82， and 2.71 sheep/（hm²·a） and plant community was categorized into five plant functional groups-perennial rhizomatous grasses， perennial forbs， perennial bunchgrasses， annual–biennial herbs， and shrubs/sub-shrubs. Quadrat sampling was used to measure plant height， cover， density， above-ground biomass， and species composition in August 2022. We calculated importance values and applied principal component analysis （PCA） to evaluate productivity-diversity coupling. Results showed that：（1） Species richness exhibited a hump-shaped response to stocking rate （22， 24， 22， and 21 species， respectively）， while morphological traits and productivity of the plant functional groups generally declined with increasing grazing pressure. （2） Importance-value analysis showed that the relative importance of perennial bunchgrasses increased from 40% to 68%， while their contribution to community productivity rose from 60% to 95%. PCA further indicated that productivity and diversity together accounted for 66.12% of the variance， which was primarily driven by this functional group.（3） A positive linear relationship was observed between species richness and productivity in the perennial forb group under no grazing， light grazing， and moderate grazing， whereas this relationship under heavy grazing was found in shrubs/sub-shrubs group. No other functional groups exhibited significant correlations. These results demonstrate that while stocking rate significantly alters plant functional group composition， species diversity alone is not a direct determinant of productivity， indicating complex interactions among disturbance， diversity， and productivity. Since perennial bunchgrasses play a crucial role in supporting productivity at higher stocking rates， grazing management strategies should prioritize the conservation and regulation of this functional group to ensure sustainable use and the ecological stability of the desert steppe.

In order to investigate the root-specific genes regulating root growth of alfalfa （Medicago sativa），transcriptome sequencing was performed to analyze differentially expressed genes （DEGs） and their functions between the aerial parts （stems and leaves） and root system of alfalfa cultivar Zhongmu No. 1. The results showed that compared to aerial parts，a total of 15258 DEGs were identified in root system，including 5095 up-regulated and 10163 down-regulated. The GO functional annotation demonstrated significant enrichment of these DEGs in cellular process，metabolic regulation，and biocatalytic activities. KEGG pathway enrichment analysis showed significant enrichment of these DEGs in pathways related to porphyrins and chlorophyll metabolism，photosynthesis-antenna protein synthesis，and carbon fixation in photosynthetic organisms. Six candidate up-regulated genes exhibiting significant differential expression were selected for real-time quantitative PCR validation. The results indicated high concordance between their expression patterns and transcriptome sequencing data.

Nitrogen deposition represents a critical driver of nitrous oxide （N₂O） emissions in global terrestrial ecosystems， with profound implications for climate change prediction. Although numerous studies have investigated soil N₂O emissions patterns in response to nitrogen addition， controversies persist regarding the regulatory mechanisms and driving factors. Through a meta-analysis intergrading the 87 global studies， we demonstrate that nitrogen addition significantly enhances soil N₂O emissions. This effect is particularly pronounced under high nitrogen application rate （>200 kg/hm² year）， in low-precipitation regions （≤400 mm annual rainfall）， and with short-term and moderate-term nitrogen application （≤3 years）. Our analysis identified nitrogen input level， mean annual precipitation， and ecosystem type as the dominant factors controlling global N₂O emissions， providing a scientific foundation for developing targeted emission mitigation strategies.

This research aims to investigate the effects of variations in precipitation on the ecological stoichiometry of soil organic carbon （SOC）， total nitrogen （TN）， and total phosphorus （TP） in desert steppes and to reveal the response of C， N， and P and their ecological stoichiometry to precipitation gradients in desert steppe ecosystems. The experiment was conducted in temperate desert steppe on the southern edge of Mu Us Desert， Yanchi County， Ningxia Hui Autonomous Region. Five precipitation levels， 33%， 66%， 100%， 133%， and 166% of natural precipitation （G1， G2， G3， G4， G5）， were simulated by rainout shelters and manual water replenishment. Variation patterns of SOC， TN， TP contents across soil layers （0-10 cm，10-20 cm， and 20-30 cm） were analyzed under different precipitation levels. The results indicate that： （1） When precipitation increased （G4）， the SOC， TN， and TP contents， and soil C∶P and N∶P ratios in 10-20 cm and 20-30 cm soils were significantly lower than in 0-10 cm soils （P<0.05）. However， the TP content did not respond significantly to precipitation changes. （2） With the increasing of soil layer depth， the correlation between the contents and ratios of SOC， TN， and TP within soil followed the order of 20-30 cm>10-20 cm>0-10 cm； （3） The variation in the SOC， TN， and TP contents was the highest in the 20-30 cm layer， followed by the 10-20 cm， and was the lowest in 0-10 cm. The variation of soil TP content was the least for all the three soil layers. In conclusion， precipitation changes have a significant impact on the ecological stoichiometry of soil carbon， nitrogen， and phosphorus， and the variation of carbon， nitrogen， and phosphorus in deep soil is greater. Deep soil （20-30 cm） is more responsive to precipitation changes than surface soil （0-20 cm）， indicating that the ecological stoichiometry of desert steppe soils is more sensitive to precipitation in deeper layers.

For the research of difference on chemical components from root exudates for alfalfa （Medicago sativa） under different growth years in northern Shanxi Province， GC-MS method was applied to analyze chemical composition and relative concentrations. Soil nutrient， soil microbial biomass carbon/nitrogen and urease were also analyzed. Results revealed that 79 types of substances were identified from the root exudates of alfalfa under different growth years， mainly including alkanes， esters， alcohols， phenols， aldehydes， etc. The types and amounts of compounds secreted by alfalfa roots in different growing years were different. 9 of the substances were contained mutually in alfalfa plants under different growth years， which were pentadecane， hexadecane， heptadecane 2， 6， 10-trimethyltetradecane， 2， 6， 10-trimethylpentadecane， heptacosane， 2， 4-bis （1，1-dimethylethyl）-phenol， 2， 2'-methylene bis-（4-methyl-6-tert-butyl） -phenol， and methyl octadecanoate. With the extension of alfalfa growth years， concentration of soil organic carbon， total nitrogen， alkali-hydrolyzed nitrogen， and available potassium followed the trend of increasing firstly and then decreasing， whereas the contents of soil microbial biomass carbon/nitrogen had an trend of increasing.

Salt stress leads to the accumulation of reactive oxygen species （ROS） in plants， causing damage to plant cells. However， the enzymatic antioxidant system is responsible for scavenging ROS in plant cells and protecting cells from ROS damage. At present， there are few functional analyses of genes related to ROS-scavenging enzymes in alfalfa （Medicago sativa） in response to salt stress. Based on the transcriptome data of roots and leaves of salt-tolerant alfalfa cultivar （GIB） and salt-sensitive cultivar （LS） under salt stress， this study identified 28 differentially expressed genes related to ROS-scavenging. Twenty-eight genes are distributed on 19 chromosomes， belonging to five gene families： MsGST， MsPOD， MsAOX， MsGRX and MsPrdx， among which MsGST （12） and MsPOD （11） families account for the largest proportion. The physicochemical properties of ROS scavenging enzyme proteins were different among the members of each gene family. There were highly similar conserved motifs in the members of the gene family. Phylogenetic analysis showed that MsGSTUs and MsPODs were located in the branches defined by Tau and AtPERs in Arabidopsis thaliana， respectively， suggesting that they had similar evolutionary processes and similar functions.Real-time fluorescence quantitative PCR analysis showed that the expression levels of MsGSTU26， MsPOD2 and MsPOD4 genes in GIB leaves under salt stress were significantly higher than those in LS， and the promoter regions of the three genes had elements （G-box and CGTCA-motif） related to adverse stress. It indicated that the MsGSTU26， MsPOD2 and MsPOD4 genes may be involved in the regulation of the adaptability of GIB and LS to salt stress.

This study investigated soil nitrogen mineralization responses to precipitation changes during the anthropogenic grassland-shrubland transition in the eastern desert steppe of Ningxia. A controlled litter-water manipulation experiment was conducted， including three litter treatments （grass， shrub， CK） and two precipitation treatments （+40% and -40%）， to assess soil nitrogen mineralization patterns under different simulated precipitation regimes. The results showed that compared with grass litter， the soil microbial biomass nitrogen in desert grassland and grassland edge soils were more sensitive to shrub litter under high precipitation conditions， and in shrubland the soil microbial biomass nitrogen was more sensitive to shrub litter under reduced precipitation （P<0.05）. Under increased precipitation， shrub litter led to an increasing trend in soil ammonium nitrogen and net ammonification rates significantly increased during the transition （P<0.05）， whereas soil microbial biomass carbon， microbial biomass nitrogen， and nitrate nitrogen along with its mineralization rate declined. Under reduced precipitation， soil nitrate nitrogen and net nitrification rates increased， and microbial biomass carbon and nitrogen in shrubland were significantly higher than those in desert steppe （P<0.05）. Throughout the transition process， the soil inorganic nitrogen and its mineralization rate were significantly affected by both litter type and precipitation （P<0.05）. Among these factors， the positive effect of increased precipitation on ammonium nitrogen was greater than that of litter， whereas nitrate nitrogen and net nitrification rate were primarily regulated by litter type （P<0.05）. In conclusion， shrub litter exerted a markedly stronger stimulatory effect on soil nitrogen mineralization than grass litter， thereby playing a dominant role in soil nitrogen cycling during grassland-shrubland transition. Specifically， under higher precipitation， shrub litter mainly enhances soil ammonification （NH{}_{\mathrm{4}}^{+} accumulation）， while under reduced precipitation， nitrogen mineralization shifted toward a nitrification-dominated pathway （NO{}_{\mathrm{3}}^{-} generation）.