Under the context of global climate change， the influence mechanism of grassland degradation on soil carbon cycling remain poorly understood. In this study， we investigated 15 paired degraded and non-degraded grassland sites on the Qinghai-Tibet Plateau， integrated microcosm incubation， metagenomics and metabolomics to assess the impacts of degradation on key carbon cycling processes， organic carbon fractions， microbial functional genes， and metabolic intermediates. The results showed that grassland degradation significantly reduced labile carbon pools， with particulate organic carbon， dissolved organic carbon， and microbial biomass carbon decreasing by 48.21%， 30.87%， and 20.21%， respectively. Meanwhile， soil organic carbon mineralization increased by 56.71%， and carbon accumulation efficiency declined by 32.51%. Degradation also led to a decrease in the diversity of carbon cycling functional genes （-2.95%， P<0.05）， while the abundance of starch-degrading genes and carbohydrate-related metabolites increased significantly （by 9.39% and 49.6%， respectively）. These changes indicated that intensified microbial carbon limitation and a shift in metabolic strategy from synthesis to decoomposition. This study elucidates the key mechanisms underlying soil carbon cycling responses to grassland degradation from a multi-factor coupling perspective， revealing that environmental factors and microbial traits jointly regulated carbon cycling， with microbial functional genes and metabolic intermediates playing a dominat role.

Soil physical structure plays a crucial role in maintaining grassland ecosystem functions and its formation is intimately linked with plant root systems. However， it remains unclear how different management practices affect soil structure and water retention throughout the profile by regulating belowground biomass （BGB）. This study compared the effects of four management practices—fencing， continuous grazing， rest grazing， and mowing—on soil physical structure （bulk density， pore distribution， aggregate composition）， water retention， and BGB in the 0-10， 10-30， 30-60， and 60-100 cm soil layers. The results showed that the response of soil structure to management was primarily concentrated in the surface layer. In the 0-10 cm layer， continuous grazing significantly reduced BGB， leading to increasing bulk density， decreasing porosity， and a reduction in macroaggregates. In contrast， rest grazing effectively mitigated soil compaction and maintained soil structure by sustaining higher BGB. Macroaggregates were the most sensitive indicator of management， with impacts extending to a depth of 60 cm. Furthermore， both pore structure and water-holding capacity were significantly and positively correlated with BGB. In conclusion， BGB is a key driver of soil structural changes， and rest grazing， by promoting root development， helps to enhance soil structural stability and water storage capacity.

Puccinellia tenuiflora is a halophyte with remarkable adaptability to the combined stress of saline and stagnant. The apoplastic barrier formed by endodermal thickening is likely crucial for this adaptation， in which the Casparian strip and suberin lamellae serve as key apoplastic barriers in endodermis for the radial transport of water and solutes. In this study， using Puccinellia tenuiflora as material， we cloned PtCASP1， a key gene involved in Casparian strip formation. Bioinformatic analysis， subcellular localization， and expression pattern analysis under saline， stagnant and combined saline-stagnant stresses were conducted. The results showed that the PtCASP1 gene was 552 bp in length， encoding 184 amino acids. It was a hydrophobic， stable protein and contained cis-acting elements responsive to gibberellin， drought stress， low temperature stress， and light response. Phylogenetic analysis indicated that PtCASP1 was closely related to those in Lolium multiflorum and Alopecurus aequalis. Immunofluorescence analysis revealed that the PtCASP1 protein exhibited dual localization in the nucleus and cell membrane. The expression level of the PtCASP1 gene in the roots of Puccinellia tenuiflora was significantly higher than that in the leaves， and it responded to saline， stagnant， and combined saline-stagnant stresses， with the highest relative expression levels at 72 hours post-treatment for all stress conditions. This study provides a reference for further investigation into the function of the Casparian strip in helping Puccinellia tenuiflora adapt to saline-stagnant combined stress.

Aldo-keto reductase （AKR） is widely present in various organisms and plays key roles in plant growth， development and stress responses. Bermudagrass （Cynodon dactylon （L.） Pers.） exhibits rapid growth and strong comprehensive stress tolerance， making it widely utilized in landscaping， turfgrass for sports fields， ecological restoration and forage production. In this study， a total of 88 members of AKR gene family were identified from the bermudagrass genome， which were clustered into 7 subfamilies and unevenly distributed across the 30 chromosomes of bermudagrass. Analysis of cis-acting elements in the promoter regions indicated that all the members contain varying numbers of light-responsive， hormone-responsive and stress-responsive elements， suggesting that this gene family may be involved in multiple growth， developmental， and stress response processes. Different AKR gene members exhibited distinct expression patterns under different salt treatment durations and in different organs. The overall expression response intensity of genes in roots was generally higher than that in leaves， with a greater number of genes being upregulated， whereas most genes in leaves were downregulated. Among them， CdAKR15， CdAKR30， CdAKR43， CdAKR48， CdAKR72， and CdAKR80 showed significant differences in expression levels under different salt stress durations. This study lays a foundation for further investigation of the response of bermudagrass AKR genes to salt stress.

Seed heteromorphism is a critical adaptive strategy for invasive plants to cope with environmental heterogeneity. To investigate the response mechanisms of heteromorphic seeds of Cenchrus spinifex， we examined germination characteristics of its two seed types （M-type： larger； P-type： smaller） under varying light （complete darkness vs. 12 h light/12 h dark） and moisture conditions （simulated by PEG gradients）. Subsequent seedling growth， biomass allocation， and phenotypic plasticity were analyzed in response to the interaction between water availability （normal， mild， and severe drought） and light intensity （high and low intensity）. The results showed that germination was unaffected by light but strongly inhibited by water stress； under severe drought， M-type seeds outperformed P-types in root length， bud length， and biomass. As seedlings， M-type plants showed higher phenotypic plasticity in morphological traits （plant height， tiller number， leaf area）， favoring increased aboveground resource investment for rapid life cycle completion， whereas P-type plants exhibited greater plasticity in biomass allocation， enhancing stress tolerance through increased root biomass proportion. In summary， the complementary germination and growth strategies of heteromorphic seeds in C. spinifex represent an effective “bet-hedging” mechanism， which is crucial for its successful invasion and spread across environmentally stressful and variable habitats.

This study investigated the physiological and molecular mechanisms underlying the cold tolerance of Caucasian clover （Trifolium ambiguum M. Bieb.）， a perennial forage known for its strong hardiness. Seedlings grown at 20℃ served as the control （CK）， and low-temperature stress （4℃） was applied for 2， 6， and 12 h. Physiological indicators were measured at each time point， and transcriptome sequencing was conducted on the control and 12 h-stressed plants. The results indicated that under 4℃， the plants enhanced their cold tolerance by significantly increasing the activities of antioxidant enzymes （peroxidase， catalase， and superoxide dismutase） and the levels of osmoregulatory substances （soluble protein， soluble sugar， and free proline）. This coordinated response effectively scavenged reactive oxygen species and mitigated membrane lipid peroxidation， as evidenced by reduced malondialdehyde accumulation. Transcriptome analysis identified 15 428 differentially expressed genes （DEGs） after 12 h of cold stress， with 8909 up-regulated and 6519 down-regulated. Key pathways were significantly activated， including the flavonoid biosynthesis pathway， where the up-regulation of pivotal upstream genes （CHS and CHI） facilitated the synthesis of antioxidant compounds such as luteolin， apigenin， and isoflavones. Concurrently， the MAPK signaling pathway was induced， highlighted by the increased expression of genes like MEKK1， suggesting that cold signals are transduced via a phosphorylation cascade. These findings provide crucial insights into the molecular basis of cold adaptation in Caucasian clover.

This study employed high-throughput transcriptome sequencing to analyze gene expression changes in Medicago truncatula under salt stress （150 mmol·L^-1 NaCl） and alkali stress （135 mmol·L^-1 NaHCO₃+15 mmol·L^-1 Na₂CO₃） at five time points： 0 h， 6 h， 12 h，24 h and 48 h. The results showed that alkali stress induced more drastic gene expression changes， with downregulated genes generally outnumbering upregulated ones. Differentially expressed genes were significantly enriched in pathways related to ABA signaling transduction， osmotic regulation， antioxidant defense， and ion homeostasis. A total of 60 genes were commonly upregulated and 16 genes were commonly downregulated under both salt and alkali stresses. The commonly upregulated genes were mainly involved in stress-resistance mechanisms such as hormone regulation and signal transduction， whereas the commonly downregulated genes covered multiple functional categories including hormone signaling and cell wall remodeling. This study elucidates key genes involved in the responses of M. truncatula to salt and alkali stresses and identifies candidate genes for salt and alkali tolerance， providing a theoretical basis for molecular breeding of alfalfa.

This study was conducted in an alfalfa field at the Luhuatai experimental site of the Institute of Plant Protection， Ningxia Academy of Agriculture and Forestry Sciences， where Beauveria bassiana and Metarhizium anisopliae were applied in alternate rows for three consecutive years. The results showed that both entomopathogenic fungi provided effective control of Odontothrips loti， with average control efficacies of 34.8% and 30.3%， respectively. Compared with the control， three years of B. bassiana application significantly improved soil physicochemical properties， with available phosphorus and soil organic carbon increasing by 67.2% and 41.7%， respectively， showing greater improvement than M. anisopliae. Soil enzyme activities were also enhanced， with increases of 36.91% in sucrase， 64.20% in alkaline phosphatase， and 31.03% in catalase. Application of M. anisopliae increased sucrase activity by 30.32% and catalase activity by 24.42% relative to the control. Compared with the soil bacterial community， soil fungal community structure was more strongly altered by the two biocontrol fungal treatments. Meanwhile， the relative abundance of beneficial taxa such as Sphingomonas increased， whereas the proportion of pathogenic fungi such as Fusarium declined. Overall， this study provides a theoretical basis and practical reference for pest biological control and the sustainable development of grassland agriculture in the Ningxia region.

To investigate the physiological regulation mechanisms of plant growth-promoting bacteria on the drought， cold， and saline-alkali stress tolerance of perennial ryegrass （Lolium perenne L.）， this study used Bacillus paralicheniformis （NCBI ID： PRJNA1402526） as the test strain. A pot inoculation experiment was conducted under three abiotic stress conditions-drought， cold， and saline-alkali stress—to analyze the effects of rhizosphere inoculation on the growth indices， physiological characteristics， and root morphology of perennial ryegrass. The results showed that inoculation with B. paralicheniformis significantly alleviated the growth inhibition caused by abiotic stresses. Compared to the non-inoculated control， the inoculated plants exhibited significantly increased plant height， above-ground and below-ground biomass， along with markedly reduced leaf relative conductivity and malondialdehyde content. Additionally， the activities of superoxide dismutase， peroxidase， and catalase， as well as the contents of proline and soluble sugars， were significantly enhanced （P<0.05）. Moreover， root system architecture was notably improved. In conclusion， inoculation with B. paralicheniformis can significantly enhance the resistance of perennial ryegrass to drought， cold， and saline-alkali stresses by synergistically strengthening its antioxidant defense capacity， osmoregulatory function， and root morphological configuration.

To investigate the effect of fertilization on the rhizosphere microorganisms of the barley-pea mixed cropping system in the Sanjiangyuan region， this study took barley （Avena sativa） and forage pea （Pisum sativum） as the research objects. A randomized block experiment including nitrogen application （A₁）， phosphorus application （A₂）， nitrogen-phosphorus combined application （A₃）， and no fertilization （CK） was set up. Soil nutrients and root morphology were measured at the milk stage， and microbial communities were analyzed using high-throughput sequencing. The results showed that under the A₂ treatment， the ratio of root volume to rhizobacteria was 11.15% and 9.49% higher than that under the CK treatment （P<0.05）； under the A₃ treatment， the root surface area was 63.37% higher than that under the CK treatment （P<0.05）. The Venn diagram results indicated that the number of soil fungi under the A₁ treatment significantly increased， accounting for 28.89%， compared to 19.12% under the CK treatment； the α diversity index and β diversity index of the A₂ treatment indicated that phosphorus fertilizer significantly increased the number of fungi in the soil， and the ecosystem tended to be stable； the fungal functional group prediction results showed that after adding nitrogen and phosphorus， the structure and quantity of soil fungi shifted towards saprophytic type. In conclusion， nitrogen and phosphorus fertilization improved the root morphology parameters and soil microbial quantity and structure， and phosphorus fertilizer was more conducive to optimizing the root morphology and microbial community structure of the artificial grassland in the Sanjiangyuan region.

To investigate the responses of soil microorganisms in alpine ecosystems under the context of increasing global nitrogen deposition， this study was conducted in an alpine meadow located in the permafrost region of Fenghuo Mountain， Qinghai Province. Five nitrogen addition levels of 0， 1， 3， 6， and 9 kg·hm^-2·a^-1 were established（denoted as N₀， N₁， N₃， N₆， and N₉， respectively）. The results showed that compared with the N₀ treatment， the N₁ and N₃ treatments significantly increased soil organic carbon content and the soil C/N ratio， whereas the N₃ treatment significantly reduced soil total nitrogen and microbial carbon content （P<0.05）. Nitrogen addition increased the relative abundances of bacterial phyla Proteobacteria and Bacteroidota but decreased the abundances of the fungal phylum Ascomycota and the archaeal phylum Thaumarchaeota. The N₆ and N₉ treatments significantly increased the Sobs and Shannon indices of bacterial communities （P<0.05）. Mantel tests indicated that soil C/N ratio and total nitrogen were key environmental factors influencing bacterial communities， while microbial carbon content， urease， sucrase， and phosphatase activities significantly affected fungal communities （P<0.05）. In summary， different microbial groups exhibited distinct responses to nitrogen addition. The diversity of bacterial community was the most sensitive to nitrogen addition， whereas fungal and archaeal communities responded more stably. This study provides a scientific basis for understanding the effects of nitrogen deposition on soil microbial communities in alpine ecosystems.

Mowing and fertilization can optimize the transfer and storage of systemic nutrients during the growing season by interfering with the physiological process of nutrient reabsorption in alfalfa. This study was to investigate the differences in nutrient reabsorption in alfalfa leaves and find the balance point of plant nutrient balance. The experiment set up five fertilization gradients （CK， F1， F2， F3， F4） under different mowing （3 times a year and 4 times a year， denoted as M1 and M2） and fertilization （P₂O₅ and K₂O ratio of 3∶5） conditions on alfalfa leaves. The carbon， nitrogen， and phosphorus contents of mature and senescent leaves were measured， and the characteristics of nitrogen and phosphorus reabsorption efficiency were analyzed. The results showed that mowing and fertilization significantly increased the nitrogen and phosphorus content in leaves （P<0.05）. The overall carbon to nitrogen ratio and carbon to phosphorus ratio in leaves showed a decreasing trend， while the nitrogen to phosphorus ratio showed a trend of first increasing and then decreasing， both of which were greater than 16. The nitrogen and phosphorus reabsorption efficiencies in leaves were 25.08%-42.79% and 29.05%-44.30%， respectively. The nitrogen and phosphorus reabsorption efficiency was significantly positively correlated with the carbon， nitrogen， and phosphorus content of new leaves. Mowing promoted nitrogen and phosphorus reabsorption， while fertilization first promoted and then inhibited it. M2F2 had the highest carbon and nitrogen content in mature leaves and nitrogen and phosphorus reabsorption efficiency in senescent leaves， making the best nutrient acquisition strategy for alfalfa.

The low germination rate of long-term stored seed of Chinese milk vetch （Astragalus sinicus L.） is an important factor limiting production， and exploring methods to promote the germination can improve their utilization and productivity. In this study， Chinese milk vetch seeds stored for 17 years and 3 years were used as materials. After soaking in distilled water （CK） and 400 mg·L^-1 gibberellin （GA₃（400）） solution， the seeds were placed in different germination substrates， including paper bed （FZ）， coconut coir （YK）， and vermiculite （ZS）， and the germination rate and seedling growth were measured . GA₃， germination substrate and the interaction between the two treatments significantly promoted the germination and seedling growth of Chinese milk vetch. Compared with CK， after soaking in GA₃， the germination rate of seeds stored for 17 years and 3 years was increased by 1.5 fold and 0.9 fold， the plant height increased by 42.6% and 72.5%， the primary root length increased by 19.1% and 45.1%， the fresh weight of aboveground increased by 12.4% and 32.3%， the fresh weight of roots increased by 7.8% and 62.8%， respectively. After soaking in GA₃， for seeds stored for 17 years and 3 years， the plant height， main root length， and root fresh weight was significantly higher under ZS than under FZ and YK. Using the membership function method to comprehensively evaluate each treatment， soaking seeds in GA₃ and planting in ZS was a suitable method to promote seed germination and seedling growth of long-term stored seed of Chinese milk vetch.

A single-factor randomized block design was used to measure the dry matter yield， dry-to-fresh ratio， crude protein content， and relative feed value of spring-sown ‘WL’ series alfalfa （Medicago sativa） varieties in the Horqin Sandy Land during the year of establishment. Multivariate analysis was employed to explore the effects of fall dormancy grade and type on the production performance. The results showed that the dry matter yield of the first and second cuttings accounted for over 60% of the total annual yield for all tested varieties， and the yield of the fourth cutting was significantly lower than that of the other cuttings （P<0.05）. ‘WL366HQ’and ‘WL349HQ’exhibited the highest total annual dry matter yield. Fall dormancy grade and type had no significant effects on dry weight or crude protein content， with negligible effect sizes， but significantly influenced relative feed value （P<0.05）. In conclusion： （1） For spring-sown alfalfa varieties in the Horqin Sandy Land， production performance during the year of establishment varied significantly among varieties and was not related to fall dormancy rating. （2） ‘WL349HQ’and ‘WL366HQ’ demonstrated the best production performance. The first and second cuttings contributed 60% of the total annual yield. Therefore， variety selection should prioritize total annual forage yield （i.e.， production performance） rather than fall dormancy rating.

To investigate the key traits influencing the seed setting rate of hulled oats （Avena sativa L.） and their regulatory pathways in the alpine habitat of northwestern Sichuan， this study utilized 27 hulled oat accessions as experimental materials. Measurements were taken for growth period， agronomic traits， photosynthetic characteristics， as well as panicle and grain traits. Multi-trait association analysis was conducted using variance analysis， correlation analysis， multiple linear regression， and path analysis. The results indicated that maturity is a key factor regulating the seed setting rate. The growth period of the tested accessions ranged from 118 to 178 d， with seed setting rates varying between 32.47% and 84.72%. The average seed setting rate of early-maturing accessions （66.93%） was significantly higher than that of late-maturing ones （56.51%， P<0.05）. Mid-maturing accessions showed the highest coefficient of variation， suggesting the existence of specific germplasms with high seed-setting potential. Traits such as panicle number， awn length， and tiller number exhibited considerable variation （CV>30%）， indicating rich genetic diversity. The seed setting rate showed a highly significant negative correlation （P<0.01） with six traits， including plant height and flag leaf length. Path analysis revealed that plant height， effective tiller number， and panicle length are key direct factors regulating the seed setting rate of hulled oats in northwestern Sichuan， primarily through the direct inhibitory effect of plant height and the direct promoting effect of effective tillers. Therefore， for this region， it is advisable to select medium-early maturing varieties with moderate plant height and a high number of effective tillers.

This study established gradient stress treatments of pH， NaCl， NaHCO₃， and Na₂CO₃ to compare the stress tolerance differences between Leymus chinensis and Elymus dahuricus. Evaluated parameters included growth indices such as seedling leaf length， root length， and fresh weight， as well as physiological indicators including chlorophyll content， relative electrical conductivity， malondialdehyde （MDA） content， superoxide anion （O₂^-·） content， antioxidant capacity， and osmoregulatory substance levels in mature leaves. A comprehensive evaluation was conducted using principal component analysis （PCA） in conjunction with the membership function value （MFV） method. The results demonstrated that alkaline salts （NaHCO₃， Na₂CO₃） exhibited significantly stronger inhibitory effects compared to neutral salt （NaCl） and high pH conditions. With increasing Na⁺ concentration and pH levels， the growth inhibition of L. chinensis was less pronounced than E. dahuricus. Additionally， L. chinensis exhibited a smaller reduction in chlorophyll content， lower increase in relative electrical conductivity and malondialdehyde （MDA） levels， less accumulation of superoxide anion radicals （O₂^-·）， and stronger antioxidant capacity compared to E. dahuricus. Additionally， L. chinensis accumulated higher levels of osmoregulation substances （soluble sugars， soluble proteins， proline）. The PCA-MFV comprehensive evaluation confirmed consistent conclusions between seedling phenotype and mature plant physiological indices， demonstrating that L. chinensis possessed significantly superior comprehensive saline-alkali tolerance compared to E. dahuricus. This research provides a theoretical foundation for vegetation selection and breeding in saline-alkali soil.

To reveal the response patterns and adaptation strategies of grassland plants in China to rainfall changes， in this study we adopted a meta-analysis to systematically analyze the effects of rainfall changes on leaf functional traits and gas exchange parameters of plants in different grasslands （meadows， typical， and desert steppes） and different functional groups. Overall， the results showed that compared with the control， under rainfall decreased conditions， the leaf area （LA， -24.80%）， specific leaf area （SLA， -6.78%）， net photosynthetic rate （P_n， -31.38%）， transpiration rate （T_r， -27.60%）， and stomatal conductance （G_s， -20.95%） were decreased significantly （P<0.05）， while the water use efficiency （WUE， 3.71%） was significantly increased. Under conditions of rainfall increase， the LA （8.07%）， P_n （24.60%）， T_r （23.94%）， G_s （26.73%） and WUE （5.75%） were increased significantly （P<0.05）， and C_i （-2.04%） was decreased significantly compared to that of the control. The results of subgroup analysis showed that desert steppe or arid areas were respectively sensitive to rainfall increase， while meadow steppe or humid areas were respectively sensitive to rainfall decrease. Under rainfall enhancement conditions， grasses or dominant species tend to adopt acquisitive strategies， while under rainfall reduction conditions， they turn to conservative strategies. This study clarifies the differentiated responses of grassland plants in northern China to rainfall changes， providing a scientific basis for predicting the stability and functional evolution of grassland ecosystems under climate change.

To elucidate the adaptive capacity of Cyperus esculentus to salt-alkali stress and clarify the synergistic effects of salt and alkali， a two-factor completely randomized design was employed using ‘Zhongyousha 1’ as the test material. Compound salt-alkali stress was imposed using six salt gradients （0， 100， 150， 200， 250， and 300 mmol·L^-1 Na⁺） and three alkali gradients （pH 7.0， 8.5， and 10.0）. Seed germination， seedling growth， leaf osmolytes， and antioxidant parameters were determined under these conditions. The results showed that germination percentage， fresh weight， and seedling length decreased significantly with increasing salt stress （P<0.05）. Notably， the lethal salt threshold under strong alkali conditions （250 mmol·L^-1） was lower than that in neutral and weak alkali environments （300 mmol·L^-1）. With intensifying stress， seedlings mitigated damage by accumulating proline， soluble sugars， and soluble proteins for osmotic adjustment， and by enhancing peroxidase and catalase activities. In conclusion， Cyperus esculentus adapted to salt-alkali stress by regulating osmotic and antioxidant capacities； however， excessive salt and alkali levels exceed its tolerance threshold， causing irreversible damage. These findings provide a scientific basis for promoting the cultivation of Cyperus esculentus in saline-alkali lands in Xinjiang.

In this study， four typical patches under the conditions of shoaly land and sloping land， including bare patches， short-term restoration patches， long-term restoration patches and healthy alpine meadow， were selected. Through plant quadrat survey， the changes of community characteristics in different types of patches during natural restoration and succession were analyzed， and their correlation with soil factors was discussed. The differences of plant community characteristics and key soil limiting factors in different types of patches were revealed. The results showed that with the restoration succession， the plant diversity of shoaly land and sloping land increased significantly， and the functional group coverage and aboveground biomass were significantly different. The quantitative characteristics， diversity， coverage of functional groups （except Fabaceae） and aboveground biomass of plant communities in shoaly land were higher than those in sloping land. Plant community indexes were positively correlated with soil water content， temperature， conductivity， organic carbon， total nitrogen， total phosphorus， nitrate nitrogen and ammonium nitrogen， and negatively correlated with pH value. Organic carbon， total phosphorus， total nitrogen and ammonium nitrogen were the key limiting factors of plant community characteristics in shoaly land， and pH， ammonium nitrogen and organic carbon were the key limiting factors of plant community characteristics in sloping land. In short， the soil conditions of the patchily degraded alpine meadow had been improved and restored， which in turn promoted the positive succession of plant communities.

Biogenic volatile organic compound （BVOC） produced and emitted by plants exhibit high chemical reactivity in the atmosphere， exerting significant influence on atmospheric chemistry and climate change. They constitute important atmospheric trace gases. To elucidate the seasonal variation patterns and driving factors of BVOC emissions in alpine meadows， this study employed a dynamic headspace sampling system coupled with GC/MS technology for in situ monitoring in alpine meadows of northwestern Yunnan from July to October 2024， concurrently recording vegetation composition and environmental factors. we detected over 130 BVOCs belonging to 11 classes， including isoprene and monoterpenes. Total BVOC emission rates exhibited pronounced seasonal variation， peaking in July [（2485.51±847.08） μg·m^-2·h^-1] and reaching a minimum in October [（206.27±166.11） μg·m^-2·h^-1]. Emissions from July to August were dominated by isoprene （nearly 100%）， while emissions from September to October exhibited greater diversity， with notable increases in green leaf volatiles， sesquiterpenes， and aldehydes. Random forest analysis indicated isoprene as the key compound distinguishing monthly emission patterns. BVOC emissions were jointly influenced by temperature， light intensity， and vegetation structure： high temperatures and strong light promoted isoprene release， whereas low temperatures and plant senescence enhanced non-light-dependent BVOC emissions. Coverage of Carex muliensis was significantly positively correlated with isoprene emissions， while co-occurring species heterogeneity and flowering period variations enhanced BVOC emission diversity. These findings would aid in our understanding of BVOC-driven atmospheric processes and climatic feedbacks within the alpine meadows of northwestern Yunnan.

Plowing and fertilization are common management practices in alpine meadows， which directly influence plant productivity and species diversity. This study established experimental plots with plowing （Dis）， nutrient addition （NPK）， and their interactive treatment （DisNPK） at the Tianzhu Alpine Grassland Ecosystem Experimental Station of Gansu Agricultural University， with natural grassland as a control （CK）. The objectives were to investigate the effects of plowing and nutrient addition on plant community structure and biomass in alpine meadows and to identify the key driving factors. By measuring soil physicochemical properties， plant biomass， and species diversity， we analyzed the relationships between soil physicochemical properties and vegetation biomass/species diversity. The results showed that all treatments significantly increased the contents of total and available soil nutrients compared to control. The NPK treatment significantly increased aboveground biomass， and the combined effect of plowing and fertilization （DisNPK） had the most significant enhancement on productivity （particularly for grasses and above-ground biomass）. The Dis and DisNPK treatments significantly reduced community diversity. Correlation analysis revealed that soil available nutrients and organic matter were positively correlated with above-ground biomass but negatively correlated with diversity indices （P<0.05）. This study demonstrates that plowing and nutrient addition can alter the community structure and productivity of the ecosystem， providing a theoretical basis for the ecological restoration of alpine meadows.

By collecting 11 forage species from the desert steppe of Siziwang Banner， Ulanqab City， Inner Mongolia， we separately determined and calculated their crude protein， ether extract， crude ash， neutral detergent fiber， acid detergent fiber， total digestible nutrients， dry matter intake， dry matter digestibility， relative feeding value， and relative forage quality. A comprehensive evaluation of the nutritional value of different forages was conducted. The study employed a combined approach utilizing the CRITIC objective weighting method and the GRA-TOPSIS comprehensive evaluation model. The results of the study showed that the three forage grasses in the grass group， in descending order of nutritional value， were Leymus chinensis > Stipa breviflora > Cleistogenes songorica； the five forage grasses in the shrub and semi-shrub group， in descending order of nutritional value， were Bassia prostrata > Krascheninnikovia ceratoides > Caragana microphylla > Artemisia frigida > Caragana stenophylla； and the three forage grasses in the weedy group， in descending order of nutritional value， were Phlomoides umbrosa > Convolvulus ammannii > Astragalus membranaceus.

Elucidating the distribution patterns and driving mechanisms of herbaceous plant diversity provides a critical scientific basis for developing ecological protection strategies. This study conducted a systematic survey of herbaceous plant communities in Yongdeng County， Lanzhou City， using a grid sampling method. We investigated four distinct habitat types-temperate steppe， temperate desert steppe， alpine meadow， and cultivated grassland-to explore the effects of topographic and soil factors on species diversity. The results indicated that： （1） A total of 356 wild herbaceous species belonging to 197 genera and 53 families were recorded. Poaceae， Asteraceae， and Fabaceae were the 3 dominant families， accounting for 38% of the total species richness. （2） The effects of topographic factors on diversity were habitat-specific. The trends of alpha-diversity indices along the elevational gradient differed significantly among grassland types， with the temperate steppe showing the most sensitive response. Species richness exhibited a significant unimodal non-linear response to slope gradient and aspect； notably， species richness peaked on shady slopes and gentle slopes due to favorable hydrothermal conditions. （3） Soil nutrients were identified as key drivers of diversity variation. Species richness was positively correlated with soil total carbon， but it showed significant negative correlations with soil total nitrogen and total phosphorus （P<0.05）. （4） Multivariate analysis further revealed that species richness was primarily driven by soil carbon content （P<0.01）. The Simpson index was significantly correlated with soil phosphorus content （P<0.01）， while the Shannon-Wiener index showed a significant co-variation with the evenness index （P<0.05）.

To investigate the effects of different grazing intensities on soil enzyme activities in a Stipa breviflora desert steppe and the driving factors， this study was based on a Stipa breviflora desert steppe and established four grazing intensity levels： no grazing （CK）， light grazing （LG）， moderate grazing （MG）， and heavy grazing （HG）. The effects of different grazing intensities on the activities of β-D-cellobiohydrolase， β-1，4-N-acetylglucosaminidase， and alkaline phosphatase were analyzed， along with species richness， aboveground net primary productivity （ANPP）， and soil pH， saturated water content， bulk density， organic carbon， available nitrogen， and available phosphorus. The results showed that with the increase of grazing intensity， the three soil enzyme activities， species richness， aboveground net primary productivity， soil organic carbon， available nitrogen， and available phosphorus all significantly decreased （P<0.05）， whereas soil bulk density was significantly increased. The Random Forest model indicated that available nitrogen and available phosphorus were the primary drivers regulating soil enzyme activities. Grazing suppresses soil enzyme activities primarily by decreasing available nutrients. This study provides a theoretical basis for the conservation and ecological restoration of desert steppes. In grassland management and utilization， measures such as controlling stocking rates and implementing seasonal grazing exclusion can be adopted.

Grassland degradation is a major driver affecting soil structure stability and carbon cycling processes； however， its underlying pathways and regulatory mechanisms under humid climatic conditions remain insufficiently quantified. In this study， a typical montane meadow in Nanshan Pasture， Hunan Province， China， was selected to investigate the characteristics of soil aggregate structure and organic carbon distribution across a degradation gradient， including non-degraded （ND）， lightly degraded （LD）， moderately degraded （MD）， and heavily degraded （HD） grasslands within the 0-30 cm soil layer. The results showed that， with increasing degradation intensity， the proportion of >5 mm macroaggregates decreased by approximately 47%， whereas the proportion of <0.25 mm microaggregates increased by approximately 168%. Meanwhile， the mean weight diameter （MWD） and geometric mean diameter （GMD） of both mechanically stable and water-stable aggregates declined by approximately 46% and 53%， respectively， accompanied by a significant increase in fractal dimension， indicating a transition of soil structure from a stable state to a fragmented state. The breakdown of macroaggregates released organic carbon， part of which was subsequently adsorbed and stabilized by microaggregates， resulting in a shift in carbon distribution from a “macroaggregate-dominated” pattern to a “microaggregate-dominated” pattern. Grassland degradation also led to a decline in total soil organic carbon and induced substantial structural reorganization of soil carbon pools， highlighting the pivotal role of soil aggregates in carbon protection and redistribution. These findings elucidate the structural mechanisms underlying carbon pool dynamics driven by grassland degradation in humid regions and provide a theoretical basis for ecological restoration and carbon sequestration management of degraded grasslands.

Grassland plants achieve species coexistence through differentiated resource utilization， which directly affects the community structure and stability. To explore the impacts of grassland utilization patterns on the coexistence mechanism of community species under the background of nitrogen deposition， four nitrogen addition levels （0，2，5，10 g·m^-2·a^-1） were set up in the moving and fenced grasslands of the Huihe River Basin in Hulun Buir， and the response patterns of plant community diversity， overall interspecific association and niche characteristics to grassland utilization patterns and nitrogen deposition were investigated. The results indicated that mowing grassland was more sensitive to nitrogen addition. Under high nitrogen conditions， species diversity significantly decreased（P<0.05）， and the overall community association weakened and turned negative. The proportion of high niche overlap decreased from 56.06% under N₂ to 31.82% under N₅， while the proportion of low overlap increased to 53.03%. The overall correlation of the fenced grassland was relatively stable； the niche breadth of Leymus chinensis and Stipa baicalensis expanded to 2.77 and 2.67 in the medium nitrogen stage， respectively， but contracted and the overlapping ratio decreased in the high nitrogen stage. Nitrogen addition reshaped interspecific relationships by altering resource availability， while the utilization method of grasslands determined the stability of the community and the ability of ecological niche adjustment； the grassland steppe community exhibited a response of low nitrogen promoting and high nitrogen inhibiting to nitrogen addition.

Basing on the livelihood vulnerability assessment framework， this study constructed a theoretical model of herders’ livelihood vulnerability. Using field survey data from 414 herder households in the pastoral areas of Inner Mongolia， the comprehensive index method was employed to evaluate their livelihood vulnerability. Furthermore， an Ordinary Least Squares （OLS） regression model was applied to analyze the impacts of herders’ climate change adaptation behaviors on their livelihood vulnerability. The results indicated a correlation between herders’ livelihood vulnerability and grassland resource endowments. Furthermore， adaptation behaviors such as purchasing forage and increasing the number of days of stall-feeding were found to exacerbate their livelihood vulnerability. Adaptation measures， such as selling weak livestock， constructing sheds， adjusting livestock composition， and well-digging， had a mitigating effect on herders’ livelihood vulnerability. The impact of grassland ecological compensation and reward policies on livelihood vulnerability exhibited a threshold effect and heterogeneity. Based on the research conclusions， the following recommendations were proposed： creating a pastoral innovation network， providing climate-adaptive technical guidance， and establishing a dynamic adjustment mechanism to formulate regionally differentiated compensation and reward standards. These measures aimed to serve as a reference for the government in formulating effective policies to alleviate herders’ livelihood vulnerability， enhance their capacity to withstand climate change shocks， and promote the sustainable development of animal husbandry.

To explore the amelioration effect of intercropping salt-tolerant forage grasses with halophytes on saline-alkali soils， a field experiment was conducted with four treatments： CK （monoculture of Echinochloa frumentacea）， T₁ （intercropping E. frumentacea with Suaeda salsa）， T₂ （intercropping E. frumentacea with Atriplex aucheri） and T₃ （intercropping E. frumentacea with Salicornia europaea）. The synergistic effects of intercropping different halophytes on soil quality and E. frumentacea yield were investigated. Compared with CK， all the intercropping treatments significantly reduced bulk density （BD）， pH and total dissolved salts （TDS） in the 0~40 cm soil layer. The largest reductions （8.84%， 7.19% and 19.86%， respectively） were observed under T₁. Soil total porosity （STP）， soil organic matter （SOM）， alkali-hydrolyzable nitrogen （AN）， available phosphorus （AP） and readily available potassium （AK） were markedly increased， with T₁ showing the greatest increments （13.38%， 26.02%， 60.01%， 26.46% and 22.13%， respectively）. Activities of soil urease （UE）， invertase （INV） and catalase （CAT） rose by 48.86 %， 45.51% and 54.11% under T₁， providing a favorable soil environment for seedling emergence and growth of E. frumentacea. Grain yields under T₁， T₂ and T₃ were significantly higher than that of CK， with increases of 55.71%， 40.01% and 20.95%， respectively. E. frumentacea yield was positively correlated with STP， soil fertility indices and enzyme activities， and negatively correlated with BD and salinity-alkalinity indicators. The soil quality index （SQI） calculated from the full dataset ranked the treatments as T₁>T₂>T₃>CK. In conclusion， intercropping E. frumentacea with S. salsa is the optimal pattern for improving saline-alkali soil quality and crop productivity， and can serve as an effective biological amelioration measure in the Ningxia Yellow River irrigation district and similar ecological regions.

This study implemented no-till reseeding of alfalfa （Medicago sativa） with irrigation （applied only in the establishment year） to restore degraded grassland in Yuyang district， Shaanxi Province. By investigating vegetation characteristics of enclosure， irrigation， the first year and the fourth year of alfalfa reseeding grasslands， the effects of restoration measures were evaluated to provide technical supports for the restoration of degraded grasslands in this region. The results showed that： （1） irrigation， as well as the first year and the fourth year of reseeding， significantly increased vegetation biomass and plant diversity compared to enclosure alone， while irrigation alone significantly increased the dry weight proportion （DWP） of annual grass and forb in the vegetation and decreased that of perennial grass， posing a potential threat to grassland ecosystem stability； （2） compared to irrigation alone， reseeding in the first year significantly increased the DWP of legume and decreased that of annual grass in the vegetation， indicating an optimized community structure； （3） as for reseeding in the fourth year， the community biomass reached 5321 kg·hm^-2， which was 5.58 and 2.63 times that of the enclose and irrigation， respectively， and there was 67.78% of the biomass contributed by the reseeded alfalfa， demonstrating high production potential while maintaining plant diversity. In conclusion， the reseeded alfalfa could be maintained in the improved grassland over the long term and reseeding alfalfa with irrigation （applied only in the establishment year） can be served as a primary measure for restoring the degraded grassland in this region.

Soil salinization restricts the development of agriculture in the Hexi Corridor. In this study， the saline-alkali soil in Guazhou County was taken as the object， and four treatments were set up as no modifier （T₀）， straw granular fertilizer （T₁）， no-tillage （T₂） and Hekang （T₃） to explore the effects of different modifiers on the growth of forage maize， soil nutrients and salt ions. The results showed that soil organic matter， available nitrogen， phosphorus， potassium， Ca²⁺，Mg²⁺， pH and total salt decreased first and then increased under different treatments. Na⁺ increased first and then decreased， K⁺ increased， Cl^-，SO₄^2- and HCO₃^- decreased. With the deepening of soil layer （0-100 cm）， pH， total salt， Na⁺，Cl^-，SO₄^2- increased， while K⁺，Ca²⁺，Mg²⁺and HCO₃^- decreased. In the 0-20 cm plough layer， T₃ had the best effect on reducing pH， total salt and HCO₃^-， and T₂ had the best effect on inhibiting Na⁺ and SO₄^2- accumulation. T₁ significantly increased the contents of soil organic matter， available nitrogen， available phosphorus and available potassium （increased by 13.76%， 29.42%， 244.59% and 11.61%， respectively）， and had the best effect on maize stem diameter， plant height and fresh grass yield （increased by 33.47%， 56.02% and 72.28%， respectively）. In summary， straw granular fertilizer （T₁） is the best choice for the improvement of saline-alkali land in this area.

The degradation of alpine grassland on the Qinghai-Tibet Plateau severely threatens regional ecological security， creating an urgent need for restoration techniques that balance rapid vegetation recovery with long-term functional enhancement. This study employed a field-controlled experiment to systematically investigate the effects of biocrust addition， non-woven fabric covering， and their combined treatment on the ecological restoration of degraded alpine grassland. Sixteen plots were established in Gangcha County， Qinghai Province， using a randomized block design. Vegetation characteristics， soil physicochemical properties， and erosion resistance were measured. The results showed that： （1） The non-woven fabric treatment rapidly restored vegetation， and significantly increased aboveground dry matter and vegetation coverage by 375.5% and 107.6%， respectively， compared to the control. （2） The biocrust treatment facilitated long-term ecological function recovery， and enhanced plant diversity and moss crust coverage by 40.4% and 863.6%， respectively. It also significantly increased soil organic matter and total nitrogen content in the crust layer by 20.8% and 13.1%. （3） The comprehensive treatment exhibited the strongest synergistic effect， reducing the soil erosion modulus by 83.1% compared to the control group. In conclusion， non-woven fabric covering is suitable for rapid vegetation recovery， biocrust addition promotes long-term soil improvement and biodiversity， and their combination offers synergistic advantages in enhancing nutrient availability and controlling soil erosion. This study provides an optimized multi-objective technical approach for restoring degraded alpine grassland.

This study aimed to investigate the interspecific nutrient competition characteristics and their effects on the productive performance of an oat （Avena sativa L.） and forage pea （Pisum sativum L.） system under different intercropping ratios in Corral lands of the Qinghai alpine region. A field experiment was conducted in Haiyan County， Qinghai Province， from 2023 to 2024， with treatments including Avena sativa∶Pisum sativum intercropping ratios of 2∶1 （O2P）， 1∶1 （OP）， and 1∶2 （OP2）， as well as monocropping oat （MO） and monocropping pea （MP） as controls. Measurements included dry matter yield， plant height， leaf area， stem-to-leaf ratio， contents and accumulations of nitrogen （N）， phosphorus （P）， and potassium （K）. The land equivalent ratio （LER） and competition rate （CR） were calculated. The results showed that： （1） The LER values under all intercropping ratios were greater than 1， with the OP treatment exhibiting the highest value， indicating that intercropping provided an advantage in land resource utilization； （2） The yield CR of oat was consistently greater than 1， demonstrating that intraspecific competition predominated， whereas the CR of pea was less than 1， indicating stronger interspecific competition； （3） Oat exhibited stronger competitive ability for N and P than pea across all intercropping ratios， while competition for K varied with the ratio-pea outperformed oat only under the OP2 ratio； （4） The OP treatment achieved the highest dry matter yield， despite oat individual leaf area being the lowest in this treatment， suggesting that the high system productivity relied primarily on interspecific functional complementarity and population synergy rather than individual morphological advantages. In conclusion， oat/pea intercropping enhances system productivity through resource complementarity and competition coordination， with the 1∶1 intercropping ratio being a suitable model for forage production in alpine Corral lands.

To investigate the effects of staged nitrogen （N） application combined with the nitrification inhibitor 3，4-dimethylpyrazole phosphate （DMPP） on nitrogen uptake， utilization， and yield of forage oat （Avena sativa L.）， a field experiment was conducted with seven N fertilizer treatments： no N application （CK）， conventional N application （105 kg·hm^-2， N₁₀₅； 210 kg·hm^-2， N₂₁₀； 300 kg·hm^-2， N₃₀₀）， reduced-staged optimized N application （168 kg·hm^-2， O₁₆₈）， and reduced-staged optimized N application combined with DMPP （O₁₆₈+D， O₁₄₄+D） The results showed that compared with conventional N application， the O₁₆₈+D treatment achieved the highest yield of 7412.13 kg·hm^-2， which was significantly higher than that of under conventional N application （P<0.05）. Compared to the N₂₁₀ treatment， the oat plant nitrogen uptake， nitrogen agronomic efficiency， and nitrogen use efficiency increased by 4.90%， 48.51%， and 6.44% in O₁₆₈+D treatment， respectively. Therefore， under the condition of Horqin aeolian sandy soil， the optimized treatment-combining reduced-staged application of N with DMPP can increase the yield and improve the N use efficiency of forage oat. These findings provide a theoretical basis for enhancing the yield of forage oat and optimizing N fertilizer application in the Horqin Sandy Land.

The expansion of Stellera chamaejasme is an important indicator of steppe degradation， which markedly alters the structure and function of steppe community. In this study， the natural typical steppe in West Ujimqin Banner， Xilingol League was selected as the research object， and the differences in community characteristics among S. chamaejasme-dominated degraded steppe （SS）， non-S. chamaejasme-dominated degraded steppe （NS） and undegraded steppe （CK） were compared. The results showed that： （1） Steppe degradation reduced community height and coverage， while the community height of SS was higher than that of NS， and the aboveground biomass of SS was significantly higher than that of CK and NS. （2） The species richness and diversity indices of NS were lower than those of SS， and a community dominated by Cleistogenes squarrosa was formed in NS. （3） There were no significant differences in the cumulative dominance of dominant families and functional groups between the two types of degraded grasslands. However， in terms of the percentage composition of functional groups， perennial graminoids （Pg） dominated in NS， while perennial forbs （Pf） accounted for the highest proportion in SS. In summary， the expansion of Stellera chamaejasme induced changes in community composition and species reduction， but it maintained community diversity and a relatively high level of aboveground biomass， indicating that the corresponding communities might be in an “alternative steady state”. Therefore， the restoration strategies for Stellera chamaejasme-dominated degraded grasslands should be distinguished from other types of degraded grasslands.

Bacterial extracellular polysaccharides （EPS） show great potential in enhancing plant stress resistance， but their mechanism of action on drought resistance in alfalfa （Medicago sativa） remains unclear. In this study， Alfalfa ‘Juneng 551’ was used as the experimental material， and seed coating technology was employed to investigate the drought resistance effect of Cp2-EPS from Erwinia persicina. Treatments included an uncoated control （CK）， a coating matrix control （T1）， and four Cp2-EPS concentration treatments （0.5， 1.0， 1.5， 2.0 g·L^-1， denoted as T2-T5）. Drought stress was applied after 21 days of seedling growth by maintaining soil relative water content at 40% for 14 days， and related physiological and growth indicators were measured. The results showed that Cp2-EPS coating significantly alleviated the growth inhibition caused by drought in alfalfa， with the 1.0 g·L^-1 （T3） treatment demonstrating the best effect. Compared with CK， the T3 treatment increased root length， shoot length， fresh weight， and dry weight by 17.87%， 17.87%， 74.53%， and 46.34%， respectively. Leaf photochemical quantum yield Y（II）， maximum photochemical efficiency of PSII， and total chlorophyll content were also significantly improved. In summary， Cp2-EPS seed coating can mitigate drought-induced oxidative damage by enhancing photosynthetic performance， and 1.0 g·L^-1 was identified as the optimal concentration. This study provides theoretical and technical references for developing eco-friendly drought-resistant coating agents and sustainable alfalfa production.