Grazing is one of the most important uses of grassland ecosystems,and different grassland types,grazing intensities,herbivore assemblages,grassland use types and climate change all influence the structure and function of grassland ecosystems. It is very important to understand the mechanisms of grazing and climate change on grassland ecosystems for their sustainable development. In order to provide a theoretical reference for the adaptive management and sustainable development of grassland ecosystems,this paper provided a systematic review of the mechanisms by which grazing affects the structure and function of grassland ecosystems,and provided an outlook on several important research directions in this theme,and future research issues as the following:(1) to improve spatial coupling analysis in grazing grassland ecosystems;(2) to focus on multifunctionality studies of grassland ecosystems;(3) to elaborate the multi-factorial nested experiments on grasslands in the context of global change;(4) to refine the mixed grazing experiments with different herbivore assemblages;(5) to standardize the methods of grassland ecological experiments.

In recent years,due to the continuous development of urban industry and the excessive use of chemical fertilizers,the lack of mineral elements and pollution in soil have seriously affected the sustainable development of agriculture. As a natural biological bacterial fertilizer,arbuscular mycorrhizal fungi (AMF) is able to effectively promote the absorption of mineral elements and improve growth conditions around plants. At the same time,in heavy metal contaminated soils,AMF can reduce the toxicity of heavy metal to plants and enhance the adaptability of plants to environmental changes. Up to now,great progress has been made in the researches on the physiological and molecular mechanism of AMF regulating the absorption of mineral elements by plants. A large number of mycorrhizal-induced genes have been identified,but a systematic and comprehensive summary is still lacking. Based on this,this paper summarized the relevant studies on AMF regulating the absorption of mineral elements in plants at home and abroad,and reviewed literature on the physiological and molecular mechanisms of AMF affecting the uptake of macroelements and trace elements by plants,and the mechanism of AMF alleviating the heavy metal toxicity to plant. According to the challenges and deficiencies of existing researches,the outlook is put forward,which aims to provide a certain scientific basis for the in-depth understanding of the mechanism of AMF affecting the absorption of mineral elements by plants and the agricultural application of biological bacterial fertilizer.

This study examines the relationship and dynamic changes between soil particle size, fractal dimension, and soil nutrients under different grazing treatments in a desert steppe region. The goal is to provide a theoretical basis for the formulation of grazing management strategies and the restoration of soil erosion in the region. The study analyzed the effects of grazing on soil particle size, fractal dimension, and nutrients using plots with four different grazing treatments and one control group, and further explored the relationship among these factors. The results showed:(1) Compared to the control group, as grazing intensity increased, the clay and silt content in the soil exhibited a declining trend, with clay content decreasing by 0.14% to 0.88% and silt content decreasing by 1.21% to 4.65%. In contrast, the sand content increased with grazing intensity, with an increase ranging from 1.07% to 5.53%. Enclosure and grazing exclusion effectively increased the fine particle content in the soil. (2) The soil fractal dimension gradually decreased with increasing grazing intensity, with the D value of the fractal dimension being highest in the control treatment and significantly lower under heavy grazing than in other grazing treatments. The fractal dimension was significantly positively correlated with soil clay and silt content ( P<0.01) and significantly negatively correlated with sand content ( P<0.01). Soil particle composition was identified as an important factor limiting the fractal dimension, which can serve as a critical indicator for assessing soil quality. In desert steppe regions, moderate grazing can effectively improve soil quality, but grazing intensity should be controlled to moderate levels or lower.

This study was conducted to evaluate the effects of different cover cropping strategies on the soil's physical and chemical properties,as well as the bacterial community structure in organic kiwifruit ( Actinidia chinensis) orchards in the Guanzhong Area. This experiment was conducted in 2021 at the Yangling Baiheng Organic Kiwi Orchard in Shaanxi Province. Three artificial cover cropping measures were tested: Lolium multiflorum+ Astragalus sinicus, Lolium multiflorum+ Glycine max, Lolium multiflorum+ Vicia villosa,with natural grass used as a control. The chemical properties and bacterial community structure of the soil in the topsoil(0~20 cm) were determined. The results showed that the organic matter of artificial grass increased by 8.8%~11.9% compared to the control,with the organic matter content of Lolium multiflorum+ Vicia villosa reaching 26.69 g·kg ^-1;The activities of soil urease,alkaline phosphatase,catalase were increased ( P<0.05),with Lolium multiflorum+ Vicia villosa having the most significant effect ( P<0.05). The bacterial beta diversity and the interaction relationship between bacterial communities in artificial cover cropping measures increased,while the abundance of metabolic functional genes in organismal systems significantly decreased( P<0.05). In summary,planting Lolium multiflorum+ Vicia villosa. and Lolium multiflorum+ Astragalus sinicus in organic kiwifruit orchards in the Guanzhong area can enhance the soil micro-ecological environment.

To uncover the effects of arbuscular mycorrhizal fungi (AMF) on reseeding species at different growth period,a microcosm experiment was carried out using Bromus inermis, Agropyron cristatum, Leymus chinensis,and Poa pratensis as test material. This experiment was set up as a factorial design containing two AMF inoculation treatments (with AMF,without AMF) and three growth period (seedling,jointing,jointing after mowing). We measured above-ground and below-ground biomass,root colonization,soil hyphal density,mycorrhizal growth response,and plant-available phosphorus. Our results showed that AMF inoculation increased the above biomass and below biomass of B. inermis and L. chinensis,compared with none inoculation. However,AMF inoculation did not affect the above biomass and below biomass of A. cristatum and P. pratensis at jointing after mowing period,compared with none inoculation. Mycorrhizal growth response (MGR) of four species was positive at each period,and the lowest MGR of A. cristatum, L. chinensis,and P. pratensis was at jointing period after mowing. From seedling to jointing period,AMF root colonization of these four species significantly increased. Soil hyphal density in B. inermis, A. cristatum,and L. chinensis reached the maximum level at jointing period after mowing. Therefore,the symbiotic relationships between AMF and plants depend on growth periods of plants and were species specific. Overall,from seedlings to adults,the abundance of AMF in roots and outside roots increased,while the response of MGR showed a decreasing trend. This indicated that AMF had a strong growth-promoting effect on plant seedlings,and this growth-promoting effect was not related to AMF abundance.

Plant-endophyte symbioses play an important role in alleviating abiotic and biotic stresses to plants. Under drought and salt stresses, endophytic bacteria can enhance the resistance of plant to the stresses by regulating plant photosynthesis, concentration of hormones, content of osmoregulatory substances, activity of antioxidant enzyme, and expression of genes to ensure a normal growth and development of plant. In recent years, plant growth-promoting bacteria (PGPB) inoculants have also been widely studied and applied. In this paper, we reviewed the diversity of endophytic bacteria, the regulation of plant genes by plant symbiotic endophytes and PGPB under drought and salt stresses, and provided a reference for the in-depth study of the molecular mechanism of endophytic bacteria to improve the tolerance of plant to drought and salt stresses.

The objective of this experiment was to explore the effect of Neolamarkia cadamba leaf essential oil (NCEO) on the fermentation quality and bacterial community of stylo ( Stylosanthes guianensis L.) and rice( Oryza sativa L.) straw silage. Based on the weight of fresh stylo and rice straw,adding the 0.5% and 1% NCEO into materials for 30 days ensiling. Vacuumed and sealed after three replicates of each treatment were packed into plastic bags (20 cm×30 cm). After 30 days of ensiling,the chemical composition and silage indexes of the samples were evaluated statistically. The results of fermentation parameter,protein fraction and bacterial community indicated that NCEO addition decreased ( P<0.05) pH value,ammonia-N content,and numbers of lactic acid bacteria and coliform bacteria both in stylo and rice straw silage. And lactic acid content and true protein proportion of rice straw silage increased ( P<0.05) with NCEO addition. Lactobacillus was the most dominant genus and increased with NCEO addition in rice straw silage. The NCEO addition also increased the relative abundance of Allorhizobium,Methylobacterium and Xanthomonas. In conclusion,the 1% NCEO addition was an effective way to improve the fermentation of stylo and rice straw silage.

Taking 1 329 core journal articles on the researches on saline-alkali soil improvement with plants from 2000 to 2022 retrieved in CNKI and Web of Science (WOS) databases as the data source,the data visualization software was used to qualitatively and quantitatively analyze the clustering,hot spots,co-occurrence,semantic network and other presence,and the current situation of plant improvement saline-alkali land at home and abroad was clarified from the perspectives of research trends,research hotspots and improvement effects of plant improvement saline-alkali land. The results show that the number of literature on saline-alkali land research is increasing year by year,and the effect of plants on improving saline-alkali land is a hot research problem. Herbaceous plants are the most commonly used plants in saline-alkali land improvement,and there are mainly 15 species of shrubs and trees. Planting plants can mainly reduce soil pH,salt content and salt ion concentration in saline-alkali land,improve soil physical characteristics,and increase soil fertility level. The improvement effect of different plants on saline-alkali land is different,and the establishment of saline-alkali plant bank as the basis for improving saline-alkali land is the focus of future research in this field,and the progress of saline-alkali land improvement is reviewed based on existing research,which has guiding significance for the subsequent ecological restoration and sustainable development of saline-alkali land.

In order to explore the suitable sowing date and cutting period for the production of triticale ( Triticosecale Wittmack) in semi-arid area of Ningxia,the main variety of forage triticale ‘Jinsicao 1’ in Ningxia was used as the research material,and three sowing dates (S) and two cutting dates (H) were set up to form a total of six treatments. The effects of different sowing dates and harvest dates on the production performance and nutritional quality of forage grass were studied,and the principal component analysis was used for comprehensive evaluation. The results showed that the plant height and leaf area of triticale increased significantly with the delay of sowing date and harvest date ( P<0.05). The hay yield and crude protein yield of triticale increased first and then decreased with the delay of sowing date. The treatment with the highest hay yield of triticale was S2H2 (9 665.74 kg·m ^-2),and the treatment with the highest crude protein yield was S ₂H ₁,reaching 881.15 kg·m ^-2. Different sowing dates and harvest dates significantly affected the nutritional quality of triticale ( P<0.05). The highest crude protein content was S ₂H ₂ (10.18 %),and the relative feeding value of S ₁H ₂ was the highest. The comprehensive ranking of principal component analysis (PCA) was S ₂H ₂ (sowing time:September 20. harvest time:filling stage),which was an ideal combination to balance the yield and nutrition of forage triticale,and could be used as a reference for sowing and harvesting of forage triticale in Ningxia rain-fed area.

Artificial grassland establishment is an effective method for managing grassland degradation in the Sanjiangyuan area. This study analyzed the availability of soil nutrients and the mechanism of carbon,nitrogen,and phosphorus cycling and balancing by examining the content of key nutrient elements and their proportional relationships in soils sown with different pasture grasses in the Sanjiangyuan area. The finds suggest that the contents of soil organic carbon,total nitrogen,and total phosphorus in the artificial grassland were significantly higher than those in the degraded grassland. Additionally,the soil nutrient improvement effect of mixed-seeded artificial grassland was better than that of single-seeded artificial grassland. Further correlation analyses revealed that soil C:N was limited by carbon and nitrogen,soil C:P was limited by carbon,and soil N:P was limited by carbon and nitrogen. In summary,the main limiting nutrient elements in the region are carbon and nitrogen. Therefore,supplementing these nutrients appropriately can improve the soil quality of artificial grassland. This study's results provide an valuable reference forsoil quality improvement in the Sanjiangyuan area through rational pasture mixing.

In order to qualitatively and quantitatively elucidate the research progress,research hot spots and development trends of ecology-livelihood research both domestically and internationally, 2 062 articles about the studies on relationship between ecology and livelihoods from 2011 to 2022 retrieved in the Web of Science (WOS) and CNKI databases were used to analyze the co-occurrence,hot spots,clustering and emergence of the literature data with the bibliometric analysis software CiteSpace. The results indicated that the number of publications on ecology-livelihood studies both domestically and internationally had increased slowly,and then rapidly,but had shown a downward trend in the past two years. International studies mainly focus on the fields of geography,sustainability and ecology,presenting a trend of interdisciplinary,diversified and refined research directions. Research hot spots mainly focus on biodiversity conservation,political ecology,ecological protection,livelihoods,impacts and influences. Domestic studies mainly focus on the fields of ecology and geographic sciences,with research hot spots mainly focused on livelihood and policy performance evaluation. The researches are oriented towards national policies and lacks innovation. Compared with studies of foreign countries,there is insufficient attention paid to biodiversity conservation,the relationship between ecosystem services and livelihood. Here we put forward proposals for future researches in this field in China to promote coordinated and sustainable development of ecology,society and economy.

AT-hook motif nuclear localized (AHL) protein, a small DNA-binding protein, is widely found in plant and plays an important part in plant growth and development, responses to adversity stress and hormone signaling. In order to comprehensively understand the structure and function of the AHL gene family of Populus euphratica, the physicochemical properties, gene structure, subcellular localization and expression characteristics under stress of the AHL family members of P. euphratica were analyzed by bioinformatics methods and qRT-PCR. It was showed by the physicochemical property analysis that there were 19 members of the AHL family, and all PeAHL proteins are basic and unstable hydrophilic proteins except for PeAHL16. It was showed by the gene structure analysis that all PeAHL members were intron deletion type genes. It was showed by the phylogenetic tree analysis that the members of the PeAHL family could be split into 8 subgroups based on gene types. It was showed by the conservative motif analysis that PeAHL genes clustered in the same branch had essentially the same motif composition and arrangement order. In the analysis of cis-acting elements, the most diverse and abundant elements within the PeAHL genes were found out in response to drought stress. It was showed by the quantitative real-time fluorescence analysis that the expression of PeAHLs was significantly induced by low temperature, high temperature, NaCl as well as PEG, and the expression of PeAHLs was highest under PEG treatment compared with the control-check. The results of this study provide a theoretical basis for the in-depth study of the AHL gene family of P. euphratica and offer a reference to a further analysis on the molecular mechanism of the involvement of PeAHL genes in response to abiotic stresses.

In order to reveal the impacts of future climate change on grassland ecosystems and their responses,this study assessed the spatiotemporal dynamics of global grassland ecosystems and their net primary productivity (NPP) in 2020-2100 based on four future climate scenarios (including SSP126,SSP245,SSP370,and SSP585) using an improved comprehensive sequential classification system (CSCS) and a segmentation model. Results showed that the global mean annual temperature (MAT) and mean annual precipitation (MAP) would exhibit an overall upward trend in all four climate scenarios. In the SSP126 and SSP245 scenarios,the global grassland area was expected to decrease by 1.94 million km ² and 1.78 million km ² by 2090 s,respectively,mainly due to the reduction of tundra and alpine steppe. In contrast,the global grassland area was expected to increase by 0.68 and 1.37 million km ² by 2090 s in the SSP370 and SSP585 scenarios,respectively,which was mainly caused by the increase in the area of the tropical savanna. Global grassland NPP showed an increasing trend in SSP126,SSP245,SSP370,and SSP585 scenarios,expecting to increase by 0.25,1.96,5.78,and 7.52 Pg DW by 2090 s,respectively. Tropical savanna would contribute the most. In the context of global warming and humidification,tropical savanna and tundra and alpine steppe grasslands would be more vulnerable to future climate change.

Grasslands are important natural resource and ecological barrier in our country. Grassland ecological restoration is an important part of China's ecological conservation, as well as an important approach to enhance the ecosystem service function and carbon sequestration potential of grassland. Extensive studies have been conducted on degraded grassland, and many effective restoration practices have been proposed. However, there is a lack of comprehensive and target-oriented summaries of these restoration practices. This study conducted a systematic review of domestic and international research on grassland ecological restoration based on bibliometric research approach. We summarized the three stages of grassland ecological restoration in China and explored a regional-classified-hierarchical ecological restoration model for grasslands under different regions, different degradation types and different degradation degrees. Additionally, we provided relevant suggestions for the future development of grassland ecological restoration in China, and aimed to provide scientific basis for the ecological restoration and sustainable management of grasslands in our country.

Melatonin is a small molecule indolamine hormone that widely exists in plants,and the studies have already clarified its synthetic pathway,catabolism and physiological functions. Melatonin can act as a signaling molecule to regulate plant circadian rhythms,seed germination,root and flower development,and also help to enhance the resistance of plants to various stresses. In this paper,the physiological functions of melatonin in regulating growth and development of herbaceous plants were summarized up,and its regulatory effects in response to abiotic and biotic stresses were particularly focused on. Additionally,functional study on melatonin in growth,development and stress resistance,as well as its application in stress resistance breeding in forage species were prospected. This review is expected to provide insight into improving the stress resistance,yield and quality enhancement of forage plants by using melatonin.

To better utilize alfalfa varieties and improve the efficiency and process of new variety selection,55 alfalfa varieties were used as materials in this study to analyze and evaluate agronomic and yield traits of alfalfa by coefficient of variation,genetic diversity index,correlation analysis,cluster analysis and principal component analysis. The results showed that the coefficients of variation of agronomic and yield traits were 6.89%~23.42%;the genetic diversity indexes 0.714 3~0.884 5 among which the highest diversity index was total leaf dry weight,while the lowest diversity index the stem-to-leaf ratio and fresh-to-dry ratio of the alfalfa varieties in second harvest. The 55 alfalfa varieties were divided into 3 main groups by cluster analysis,in which each group had obvious traits and characteristics;the varieties in group I and II need to be further mined for their excellent traits and can be utilized as complementary materials for breeding,and the varieties in group III can be directly introduced to the practical production,and can also be used as the parental materials in selection and breeding of highyield and good-quality varieties for the genetic improvement. Correlation and principal component analysis showed that number of branches,fresh-to-dry ratio,stem dry weight,leaf dry weight and plant height were the most important traits affecting the yield. The results of this study would provide a reference for the development and utilization of alfalfa varieties and the variety breeding of alfalfa in the semi-arid area.

In recent years, the Chinese government has continuously introduced policies to support oat cultivation. Encouraged by these policies and driven by market demand, the oat ( Avena sativa L.) industry has experienced new developments, characterized by:1) Increasingly refined support policies and a continually solidifying foundational status;2) Expanding planting scale and rising commercial rates of oat grass;3) Improving industry chains and the growing strength of outsourcing service organizations;4) Enhanced levels of intelligent production and significant advancements in digital management;5) Diversified planting models for the “three idle fields” (spring fallow fields, autumn fallow fields, winter fallow fields), with large-scale production becoming the norm. Despite the strong momentum of the oat industry, it faces several new challenges:insufficient innovation and utilization of oat germplasm resources;increasing constraints from arable land and water resources;a weak foundation for oat cultivation;and persistent contradictions between the supply and demand of high-quality oats. In response to the increasing national support and strong market demand for oat industry development, it is essential to first adopt a comprehensive food strategy by incorporating oats into livestock production elements and implementing integrated measures. Secondly, technology resources should be consolidated to enhance the utilization of oat germplasm resources and increase the innovation of new oat varieties. Finally, resource allocation should be optimized to address issues of limited arable land and water resources for oat cultivation, strengthen the utilization of oats in the “three idle fields”, and expand the planting area of oats.

Epichloë grass endophyte is a group of fungi that finish most their life cycle in the intercellular space of the host grasses,but do not cause obvious external symptoms on the hosts. As an important agricultural microbial resource,it can promote the growth of hosts and improve the host's resistance to adversity. In addition, some alkaloids produced by the symbionts formed by some endophytic fungi and their host,can cause herbivorous livestock be poisoned and affect the healthy development of grassland animal husbandry. This dual characteristic of grass endophyte has become a research hotspot in the field of international grass industry for the past 30 years. In this study,the nomenclature history,classification status of teleomorph and anamorph grass endophyte,classification methods and significance of grass Epichloë endophyte were reviewed. Moreover,the resources and the distribution of grass endophytic fungi found in China and the research progress about grass endophytic fungi in stress resistance breeding were also summarized. The review was prospected to provide scientific basis for mining and utilizing beneficial grass endophytic fungi resources,cultivating new varieties of excellent plants,developing modern grassland animal husbandry and taking the ecological environment construction.

Under the background of global climate and environmental change, to explore the effects of different gradients of nitrogen and phosphorus additions on plant community biomass, plant nutrient content and stoichiometric ratio of alpine meadow, this paper analyzed the responses of the total aboveground biomass, the aboveground biomass of functional groups, total nitrogen and total phosphorus content, and nitrogen and phosphorus ratio of plants to the multi-gradient nitrogen and phosphorus additions of typical alpine meadow in Menyuan County, Qinghai Province. The results showed that:the additions of nitrogen and phosphorus had a significant effect on the aboveground biomass of the community ( P<0.001);the nitrogen addition significant effects on the biomass of grasses and legumes ( P<0.001);the phosphorus addition significant effects on the biomass of grasses and sedges ( P<0.001);the interaction of nitrogen additions and phosphorus additions significant effects on aboveground biomass of legumes and sedges ( P<0.05). At the community level, nitrogen addition significantly increased the total nitrogen (TN) content of the community plants, and had a positive effect on the nitrogen to phosphorus ratio (N:P) of the community plants. Phosphorus addition significantly increased the total phosphorus (TP) content of the community plants, and had a negative effect on plant N:P ratio in community. The negative effect of plant TP on N:P was greater than the positive effect of TN on plant N:P ratio. Our study demostrated that the addition of nitrogen and phosphorus may change the composition and nutrient content of alpine meadow plant community, and the community would gradually develop to grassland;In addition, the growth of alpine meadow plants tends to be restricted by both nitrogen and phosphorus.

In order to study the alleviating effect of VitaCat ^® (GA·IAA·BR 0.136%WP) on seed germination and seedling growth of turfgrass under low temperature stress, two turfgrass species, Festuca arundinacea and Lolium perenne were used as the experiment material. The seeds were soaked into 2 500~15 000 times VitaCat ^® for 24 hours at room temperature (25℃/25℃), then their germination were observed under room temperature (25℃/25℃) and low temperature (15℃/10℃). The seedling were foliar-applied with 2 500~15 000 times VitaCat ^®, then their growth performance was observed under room temperature (25℃) and 10-day outdoor low temperature stress. The results showed that seed germination potential, seed germination rate and sprout length and root length of two turfgrass species under both low and room temperatures were significantly improved after the soaking-up in 7 500~10 000 times dilution of VitaCat ^®. The root length, root weight, as well as chlorophyll content, proline content and superoxide dismutase activity of those turfgrasses were significantly increased, and malondialdehyde content and relative electrical conductivity were significantly decreased under low temperature stress by spraying 5 000~7 500 times VitaCat ^®. From the above results, it can be concluded the seed soaking-up with 7 500~10 000 times dilution of VitaCat ^® improved the seed germination and growth of two turfgrasses. The foliar spraying of 5 000~7 500 times dilution of VitaCat ^® alleviated the injury of seedlings by low temperature stress and enhanced the cold resistance of seedlings.