To elucidate the initial effects of nitrogen deposition on soil organic carbon （SOC） and its stability in alpine meadows， we conducted a field nitrogen addition experiment in the eastern Qilian Mountains. Aboveground biomass， soil physicochemical properties， enzyme activities， and SOC fractions were measured， and their key drivers were identified using variance partitioning. Nitrogen addition significantly increased aboveground biomass but reduced cellulase and β-glucosidase activities （P<0.05）. Particulate organic carbon （POC） content and proportion decreased markedly， whereas easily oxidizable organic carbon （EOC） and mineral-associated organic carbon （MAOC） increased significantly （P<0.05）. POC dynamics were mainly regulated by total phosphorus and carbon-acquiring enzymes， MAOC was closely associated with aboveground biomass， pH， and β-glucosidase， while EOC was primarily driven by available phosphorus and cellulase. Overall， microbial biomass carbon （17%） and dissolved organic carbon （14.1%） primarily explained short-term SOC variations. In summary， nitrogen addition enhanced soil carbon pool stability by promoting plant carbon inputs， modulating enzyme activities， and reshaping the distribution of SOC fractions. These findings reveal the pathways through which nitrogen deposition stabilizes SOC in alpine meadows， providing critical insights into carbon cycling processes and the carbon sequestration potential of fragile ecosystems under nitrogen enrichment.

WRKY transcription factors are widely involved in plant growth and development and play important roles in biotic and abiotic stress responses. In this study we cloned the EnWRKY26 gene from Elymus nutans Griseb ‘Ba Qing’ and conducted bioinformatics analysis， subcellular localization analysis， gene expression profiling， and transcription factor activity validation. The results indicated that EnWRKY26 was 996 bp in length， encoding 331 amino acids， with a molecular weight of 35 501.70 Da. The theoretical isoelectric point of the EnWRKY26 protein was 9.49， with an instability index of 53.78 and an average hydrophobicity of -0.652， indicating that it was an unstable hydrophilic protein. The entire protein sequence lacks transmembrane domains， and its secondary structure is predominantly composed of random coils. EnWRKY26 is most closely related to TraseCS7B02G418600 and TraseCS7D02G497700 in terms of phylogenetic relationship. Subcellular localization analysis revealed that EnWRKY26 was localized in the nucleus. Transcription factor activity validation confirmed that it possesses transcriptional activation activity. Under salt stress treatment， the relative expression level of EnWRKY26 showed an increasing trend. This study provides a theoretical basis for an in-depth understanding of the molecular mechanism by which EnWRKY26 regulates the response of Elymus nutans to salt stress.

In order to explore the response of sagebrush deserts grassland community structure and biomass component allocation pattern of Seriphidium borotalense to degradation under different degradation degrees， the plant community characteristics， plant community diversity index， species diversity characteristics， and modular biomass allocation patterns of S. borotalense desert grassland in undegraded （UD）， lightly degraded （LD）， moderately degraded （MD）， and highly degraded （HD） areas were measured and analyzed. It was found that with the increase of degradation degree， the community height， coverage and aboveground biomass decreased significantly， and the density increased significantly （P<0.05）. The Patrick index did not change， and the other diversity indexes decreased significantly. The height， coverage and aboveground biomass of S. borotalense decreased significantly （P<0.05）， and the density reached the maximum at LD， but no S. borotalense was found at HD. The distribution of stem and leaf components such as plant height， stem length and leaf weight decreased significantly （P<0.05）， and the distribution of root components such as root weight， root diameter and root weight ratio reached the maximum at LD. Redundancy analysis showed that community coverage was the most critical environmental factor driving the component allocation pattern of S. borotalensei. To sum up， S. borotalense responded to grassland degradation by optimizing the component allocation pattern， and the optimization threshold was between LD and MD.

Saline-alkali land is widely distributed worldwide， and it is of great significance to screen for germplasm resources of saline-alkali resistant Bromus inermis for improving saline-alkali land In this study 100 Bromus inermis germplasm resources were selected as the reseat objects. During the seedling stage， 200 mmol·L^-1 NaHCO₃ solution was used for stress treatment， and 14 traits including plant height， root length， seedling fresh weight/dry weight， root fresh weight/dry weight were measured. Multiple statistical methods such as correlation analysis， principal component analysis， membership function analysis， and cluster analysis were used to comprehensively evaluate the alkali tolerance of different smooth brome germplasm resources. The results showed that there were varying degrees of variation in the alkali tolerance coefficients of 14 personality traits， ranging from 39.52% to 74.83%. Relative conductivity was negatively correlated with 13 indicators including plant height， root length， and seedling fresh weight. Using principal component analysis， 14 traits were classified into 3 components， with a cumulative contribution rate of 73.719%. Plant height， stem thickness， fresh weight of aboveground parts， dry weight of aboveground parts， survival rate， root surface area， root volume， and relative conductivity can be used as the main evaluation indicators for alkali tolerance at the seedling stage of smooth brome. Cluster analysis grouped 100 rootless barley seeds into three categories， including 16 alkali tolerant materials， 63 medium resistant materials， and 22 alkali sensitive materials. The results provide excellent germplasm materials for the screening of alkali tolerance indicators and the breeding of new varieties of smooth brome.

Grazing is a key human disturbance affecting the structure and function of desert steppe ecosystem. Most of the current studies focus on the response of species or functional groups at a single level， and there is a lack of systematic analysis of the changing patterns of the correlation between the two with the change of disturbance gradient. In this study， Stipa breviflora desert steppe in Inner Mongolia was taken as the object， and four stocking rate gradients were set up. By measuring the characteristics of plant populations and dividing functional groups， the relationship between dominant species （Stipa breviflora， Cleistogenes songorica， Artemisia frigida） and functional groups （life form， photosynthetic type， root type） was analyzed by grey correlation degree. The results showed that： （1） The dominant species had different responses to grazing. Stipa breviflora and Cleistogenes songorica had strong grazing tolerance， and Artemisia frigida decreased significantly with the increase of stocking rate. （2） Perennial grass （PG） was always dominant in the community， C₄ functional group performed the best under moderate grazing， and the axis root system （ARS） was sensitive to grazing. （3） Grazing intensity regulated the association pattern of dominant species and functional groups： the two were the most closely related under light grazing （LG）， the dominant species contributed the most under moderate grazing （MG）， and heavy grazing （HG） led to the weakening of functional group association and community simplification. This study revealed the dynamic response of dominant species and functional groups to grazing， and provided a scientific basis for grassland management in arid areas.

To investigate the short-term effects of biogas slurry fertilizer on the physicochemical properties of degraded grassland soil， this study investigated moderately degraded grasslands in Zhenglan Banner， Xilingol League. Four treatments were established： blank control （CK）， water control （W₀）， 50% diluted concentration of biogas slurry fertiliser （BS_50%）， and full concentration of biogas slurry fertiliser （BS_100%）. The application rate was 300 m³·ha^-1. The contents of nitrogen （N）， phosphorus pentoxide （P₂O₅） and potassium oxide （K₂O） in the biogas slurry are 0.11%， 0.07% and 0.09% respectively. Soil samples from 0~15 cm and 15~30 cm soil layers were collected to analyze their physical and chemical property indexes. The results showed that compared with CK， both BS_50% and BS_100% treatments significantly improved soil physical structure， with decreasing soil bulk density and increasing soil porosity. Applying biogas slurry fertilizer markedly enhanced soil physical and chemical properties and microbial activity. The contents of soil total nitrogen， available phosphorus and available potassium increased significantly by 14.50%-25.86%， 66.87%-204.06% and 30.26%-193.91%， respectively， while the contents of soil microbial biomass carbon and microbial biomass nitrogen increased significantly by 11.04%-18.39% and 12.47%-28.34%， respectively. This study revealed the short-term effects of biogas slurry fertilizer on the physicochemical properties of degraded grassland soils. It provides fundamental scientific evidence for restoring degraded grasslands and enhancing soil fertility， while also offering reference support for the resource utilization of biogas slurry fertilizer and the sustainable management of grassland ecosystems.

This study focued on alfalfa fields in the Loess hilly region as research objects， with four experimental treatments were established： no fertilization （CK）， nitrogen fertilizer alone （T1）， phosphorus fertilizer alone （T2）， and combined nitrogen-phosphorus fertilization （T3）. By examining the ecological stoichiometry of soil-microbe-extracellular enzyme systems under nitrogen and phosphorus addition， this research explored the characteristics of soil nutrient limitations and the feedback mechanisms of microbial communities to metabolic constraints. The results showed that fertilization significantly decreased soil carbon to phosphorus ratio， microbial biomass carbon to phosphorus ratio （MBC∶MBP）， microbial biomass nitrogen to phosphorus ratio （MBN∶MBP）， and enzymatic stoichiometric carbon to nitrogen ratio （EEA_C∶N）. In contrast， soil nutrient content， microbial biomass， extracellular enzyme activities， and enzymatic stoichiometric nitrogen to phosphorus ratio （EEA_N∶P） were significantly increased. Enzyme vector modeling and vector analysis indicated that long-term alfalfa cultivation led to varying degrees of carbon and phosphorus limitation in soil microorganisms. Nitrogen and phosphorus addition alleviated the microbial phosphorus limitation and increased microbial carbon use efficiency （CUE）. In conclusion， appropriate supplementation of nitrogen and phosphorus fertilizers is recommended for soils under long-term alfalfa cultivation in the Loess hill region， to mitigate nutrient limitations on soil microorganisms.

The experiment was designed to investigate the effects of the composite bacterial agent composed of Lactobacillus plantarum， Bacillus subtilis and Aspergillus niger and its compounding with molasses or cellulase on the silage quality and microbial diversity of corn straw. A single-factor randomized design was adopted with four treatments： control group （CK）， composite fungicide group （BC）， composite fungus with molasses group （FT）， and composite fungus with cellulase group （FX）. Each group was replicated three times， and after 30-day fermentation at room temperature， the samples were opened and sampled to determine their nutrient composition， fermentation quality and microbial diversity. The results showed that compared with the CK group， the crude protein （CP） and crude ash （Ash） contents in BC， FT and FX groups increased significantly， while the neutral detergent fiber （NDF） and acid detergent fiber （ADF） contents decreased significantly. The FX group had the highest contents of ammonia nitrogen （NH₃-N， 9.13%DM） and acetic acid （AA， 1.95%DM）. The Entropy Weight-TOPSIS evaluation indicated that the FX group had the best quality with a relative closeness degree （C_i） of 0.510. Microbial diversity analysis showed that BC， FT and FX groups significantly reduced community richness and diversity. At the phylum level， the dominant phylum in all groups was Bacillota， with the highest relative abundance in the FX group， followed by Pseudomonadota with the highest abundance in the CK group. At the genus level， the dominant genera in the CK group were mainly Lentilactobacillus， Sporolactobacillus， Clostridium， and Lactiplantibacillus， while the BC， FT and FX groups were dominated by Lentilactobacillus. In conclusion， the composite bacterial agent significantly improved the silage quality of corn stover and altered its microbial community structure， with the FX group （bacteria enzyme synergism） showing the best silage effect.

Taking the grassland in the upper reaches of the Yellow River Basin as the research object， based on multi-source data from 2000 to 2023， the degradation problem was analyzed from the dual perspectives of “grassland coverage type transformation + degradation evaluation index system”， and the CA-Markov model was used to predict the future degradation pattern. The results showed that： （1） The grassland is mainly composed of medium coverage grassland. Over the past 23 years， the total area of grassland has decreased by 2201.60 km²， and the coverage conversion has fluctuated greatly， showing obvious spatial differentiation characteristics. （2） The proportion of un-degradation grassland has decreased from 59.77% to 54.62%， showed an overall “one decrease and three increases” degradation feature. Spatially， it presented a pattern of “low in the southwest and high in the northeast”， and the area of regions with increased degradation grades was larger than that of regions with decreased grades. （3） By 2030， the proportion of un-degradation grassland will further decline， while the proportions of mild， moderate and severe degradation grassland will increase， and the degradation trend will continue to intensify. The research can provide a scientific basis for regional grassland protection and management.

To screen plant growth-promoting rhizobacteria （PGPR） that are capable of stably colonizing the rhizosphere of Stipa purpurea， four PGPR strains previously isolated from this alpine grass were evaluated. Rifampicin-resistant derivatives were generated to monitor root-zone colonization dynamics， and the effects of bacterial inoculation on seed germination， seedling morphology， and physiological indices were assessed under the culture of 15℃， 20℃， and 25℃. Serratia proteamaculans GD-1-1 and Paenarthrobacter nitroguajacolicus YD-2-4 established stable populations in the S. purpurea rhizosphere， and the colonization amounts were 1.22×10⁸ and 0.06×10⁸ CFU·g^-1 at 20 d， respectively. Dilutions of YD-2-4 （1×10¹ and 1×10² CFU·mL^-1） significantly enhanced germination and seedling growth across 15℃-25℃， concurrently increasing antioxidant enzyme activities and lowering malondialdehyde content. In contrast， the stimulatory effect of GD-1-1 （1×10² and 1×10³ CFU·mL^-1） declined with temperature and disappeared at 15℃. These results indicated that YD-2-4 possessed robust colonization ability and broad temperature adaptability， making it an excellent candidate for the development of microbial inoculants for alpine grasslands.