We studied a soil seed bank in the Stipa breviflora desert steppe under three grassland management systems, namely continuous grazing, rotational grazing, and no grazing, from 1999 until 2007. The germinable seed bank...We studied a soil seed bank in the Stipa breviflora desert steppe under three grassland management systems, namely continuous grazing, rotational grazing, and no grazing, from 1999 until 2007. The germinable seed bank species in rotational, continuous and no gazing were 11, 9 and 8 species, respectively. Rotational grazing increased the number of seed bank plant species and perenni- al grasses. The density of germinal soil seed bank was significantly higher in the enclosed area （19,533.33 seeds/m2） than those in rotational （3,233.33 seeds/mz） and continuous grazing areas （2,553.60 seeds/m2）. The vertical distribution of the soil seed bank had a similar trend： 75.06%-83.19% of the seeds are distributed in the top 0-5 cm soil layer, 14.16%-21.68% in the 5-10 cm lay- er, and 2.65%-4.95% in the 10-15 cm layer, which varied between the grazing treatments. Density of the soil seed bank was sig- nificantly higher in the enclosed area, and there was no significant difference between rotational and continuous grazing. The Margalef and Shannon-Wiener indices for the soil seed bank were higher for rotational grazing treatment than for continuous grazing. The Sorensen＇s similarity index for the soil seed bank between the enclosed and rotational grazing areas reached 0.857.展开更多
This study investigated the effects of various grazing systems, including continuous grazing, rotational grazing, and no-grazing systems, on the community biomass in the Stipa breviflora Griseb desert grassland during...This study investigated the effects of various grazing systems, including continuous grazing, rotational grazing, and no-grazing systems, on the community biomass in the Stipa breviflora Griseb desert grassland during the grazing seasons in 2005, 2006, and 2007, based on study sites established in 1999. We found that the seasonal dynamics of the aboveground biomass were quite similar among the three treatments, which reached peak values in period from August to September during each study year. The continuous grazing system reduced the aboveground biomass from 2005 to 2007 under drought conditions, and the rotational grazing and no-grazing systems maintained more aboveground biomass than the continuous grazing system did. The belowground biomass declined with the increase of soil depth among the three treatments, and in the surface 20-cm soil layer it accounted for more than 60% of the total biomass. The belowground biomass was found to be highly correlated with soil depth under rotational grazing. The total belowground biomass within the 0--100-cm soil layer for rotational grazing was sig- nificantly higher than for continuous grazing and no-grazing, and had 15,775 kg/ha more biomass. Our results demonstrate that conservative rotational grazing can alleviate grassland deterioration by reserving more aboveground and belowground biomass than the continuous grazing system does.展开更多
Forage plantain(Plantago lanceolata L.)has emerged as a valuable agronomic species within grazing systems in New Zealand.The release of two cultivars in New Zealand in the mid‐1990s led to on‐farm use and research.S...Forage plantain(Plantago lanceolata L.)has emerged as a valuable agronomic species within grazing systems in New Zealand.The release of two cultivars in New Zealand in the mid‐1990s led to on‐farm use and research.Subsequent identification of the potential of plantain for reducing nitrogen losses from intensive grazing systems led to an expansion of research and extension over the last decade.This review summarises key aspects of the agronomic use of modern forage plantain from mainly New Zealand‐based research,including environmental tolerance,forage productivity,feed quality,cultivar development,weed and pest management,grazing management and measurement of herbage mass.The agronomic advantages of including modern plantain cultivars in pastures include seasonal growth complementarity with grasses and clovers,greater summer‐drought resilience and improved forage quality.On‐farm use of plantain in New Zealand has grown to about 20%of new pastures over three decades,a modest level which can be attributed to unmet farmer expectations of plantain persistence as a substantive contributor to perennial grass‐based swards and the limitations for controlling dicot weeds.These are key areas of future research priority,along with the potential for complementarity with forage grasses other than perennial ryegrass.展开更多
Global grassland degradation necessitates the identification of sustainable grazing management strategies.In semi-arid regions,grazing exclusion(GE),cold-season grazing(CG),and free grazing(FG)represent common practic...Global grassland degradation necessitates the identification of sustainable grazing management strategies.In semi-arid regions,grazing exclusion(GE),cold-season grazing(CG),and free grazing(FG)represent common practices in grassland ecosystems,yet the long-term ecological consequences of these patterns on plant community structure and soil aggregate stability remain inadequately elucidated.In this study,we evaluated the effects of GE,CG,and FG on soil organic carbon,soil water content,soil bulk density,soil aggregates,and vegetation indicators in Xilamuren steppe,a semi-arid grassland in northern China through field sampling and laboratory analyses in 2024.Our findings revealed that,compared to CG and FG,GE significantly enhanced aboveground and belowground biomass,species diversity,and soil physical-chemical properties in the 0–30 cm layer.The dominant plant species in GE and CG sites were Stipa krylovii,Leymus chinensis,and Agropyron cristatum,whereas Stipa krylovii,Artemisia frigida,and Leymus chinensis were predominant in FG site.Different grazing patterns led to distinct soil aggregate distributions,with>2.00 and<0.25 mm aggregates exhibiting the highest content in different soil layers depending on the grazing patterns.All grazing management strategies significantly improved soil aggregate stability,with the overall stability following the order:GE>CG>FG.Furthermore,random forest modeling identified plant species diversity,plant growth traits,and grazing patterns as the primary determinants of soil aggregate stability.Collectively,these results offer valuable insights into the sustainable management and ecological restoration of semi-arid grasslands under different grazing pressures.展开更多
The connection between climatic factors and grazing is essential for maintaining ecosystem function and vegetation productivity.This study examined the impact of grazing intensity on vegetation across a broad climatic...The connection between climatic factors and grazing is essential for maintaining ecosystem function and vegetation productivity.This study examined the impact of grazing intensity on vegetation across a broad climatic gradient spanning the Espinal,Argentine Low Monte,and Patagonian Steppe ecoregions of Argentina.The research was carried out at eight sampling sites with radial grazing gradients generated around artificial water sources(piospheres),exhibiting two contrasting response patterns of vegetation to grazing pressure.One of the response patterns shows a typical vegetation response to grazing that the vegetation productivity increases with the distance to the water sources(decreasing grazing intensity).The second pattern is found in drier regions,where vegetation presents an inverse productivity response that vegetation productivity is higher near water sources(high grazing intensity)due to increased shrub cover.Vegetation productivity was measured using the Normalized Difference Vegetation Index(NDVI).Vegetation patch structure and cover were determined for each site with high,medium,and low grazing intensities.Results indicated that shrub cover is the primary driver of vegetation productivity,showing contrasting responses to grazing intensity between the two identified patterns.While NDVI proved to be a reliable proxy for shrub cover and total vegetation cover(R2>0.70),it failed to reflect grass cover dynamics.Furthermore,mean annual temperature was more strongly correlated with vegetation cover changes,while grazing intensity significantly altered vegetation patch structure and soil cover distribution.Specifically,in drier regions,high grazing intensity led to larger patches while,in wetter regions,it led to smaller patches(fragmentation).Shrubs,with their deeper roots and drought tolerance,were less preferred and more resistant to grazing in arid environments and thrived under grazing pressure in these arid conditions.Our results underscored the need for adaptive management strategies in grazing systems.Traditional approaches may require significant adjustments,as the efficacy of management hinges on the interplay of specific climatic conditions and the varied responses of vegetation.Furthermore,effective conservation efforts should prioritize the recognition and protection of shrubs given their critical contribution to ecosystem function and biodiversity.Ultimately,this research provides a valuable framework to understand the complex dynamics between grazing and vegetation in arid and semi-arid environments,highlighting that sustainable grazing practices should be tailored to account for both climatic variables and the unique characteristics of different plant communities.展开更多
The alpine grassland vegetation on the Qinghai-Tibet Plateau is composed of plant patches in varied sizes.It remains uncertain whether vegetation recovery following grazing exclusion(GE)in degraded grasslands is drive...The alpine grassland vegetation on the Qinghai-Tibet Plateau is composed of plant patches in varied sizes.It remains uncertain whether vegetation recovery following grazing exclusion(GE)in degraded grasslands is driven by increases in patches number(NP),patch size(PS),or both.We based our predictions on two hypotheses:GE intensifies plant competition,and facilitation prevails near patches while competition prevails in interpatch spaces.We predicted that the NP would remain stable or decrease and PS would increase under GE treatment.To evaluate these predictions,we conducted a study in six lightly degraded alpine grasslands under free grazing(FG)conditions in Bangor County,Xizang Autonomous Region,China,with corresponding GE treatments using transects in 2017 and 2018.Results revealed that four sites in 2017 and five sites in 2018 had reduced NP and increased PS,with probabilities of 0.033(2017)and 0.004(2018),respectively,and a joint probability of 0.0001 under the null hypothesis that GE does not affect NP or PS.The NP reduction was solely due to the decrease in small patch sizes.An increase in PS was common across species,and a predominant tendency for NP reduction was observed among species across the sites.The overall changes in NP and PS were primarily driven by the three most abundant species(contributing more than 60%in both years),rather than by shifts in floristic composition.Our findings highlight that vegetation recovery in Bangor alpine steppes following GE relies solely on the expansion of existing patches rather than the recruitment of new ones in interpatch gaps.We recommend prioritizing growth-promoting measures,such as nutrient or water management,over seed addition when assisting with GE for restoring lightly degraded grasslands.展开更多
Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF...Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF septum liner and its impedance model on the Beihang Grazing Flow Duct(BGFD)setup,over a wide frequency range under grazing flows up to 0.5 Mach number and Sound Pressure Level(SPL)up to 150 dB,typically encountered in aeroengine nacelles.Several specimens varying in the numbers,types,and depths of septa among units are designed,fabricated,and measured.Their impedances and Transmission Losses(TL)are obtained using the mirror-based multimodal straightforward method and the mode decomposition technique,respectively.Generally,the model predictions show good agreement with the educed impedances in all cases,and such liners with a large-porosity facesheet exhibit low acoustic nonlinearities in the presence of high SPL,especially under high-velocity grazing flows.Moreover,a MDOF liner we delicately designed,compared with a conventional broadband three-layer perforated liner as the reference,is close to the resonant state at more frequencies and thus has higher and wider measured TL spectra almost from 1 kHz up to 10 kHz at studied Mach numbers,under the premise of saving 22.7 mm in the thickness.These show that,the MDOF septum liner,if well designed,can achieve an ultra-broadband efficient sound attenuation using more limited spaces in complex aeroacoustic environments.展开更多
Grazing bifurcation of a relative rotation system with backlash non-smooth characteristic is studied along with the change of the external excitation in this paper. Considering the oil film, backlash, time-varying sti...Grazing bifurcation of a relative rotation system with backlash non-smooth characteristic is studied along with the change of the external excitation in this paper. Considering the oil film, backlash, time-varying stiffness and time-varying error, the dynamical equation of a relative rotation system with a backlash non-smooth characteristic is deduced by applying the elastic hydrodynamic lubrication（EHL） and the Grubin theories. In the process of relative rotation, the occurrence of backlash will lead to the change of dynamic behaviors of the system, and the system will transform from the meshing state to the impact state. Thus, the zero-time discontinuous mapping（ZDM） and the Poincare mapping are deduced to analyze the local dynamic characteristics of the system before as well as after the moment that the backlash appears（i.e.,the grazing state）. Meanwhile, the grazing bifurcation mechanism is analyzed theoretically by applying the impact and Floquet theories. Numerical simulations are also given, which confirm the analytical results.展开更多
To understand the effects of grazing activities and climate change on sandy grassland ecosystems in northem China, a livestock field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land...To understand the effects of grazing activities and climate change on sandy grassland ecosystems in northem China, a livestock field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land, Inner Mongolia. The results showed that sustained heavy grazing resulted in serious degradation of the vegetation; moderate grazing can maintain vegetation stabilization; and light grazing can promote rapid restoration of degraded vegetation. The livestock productivity was the highest in the moderate grazing grassland, and sustained heavy grazing resulted in rapid decrease of the livestock productivity. Heavy grazing can cause a retrogressive succession of grassland vegetation, whereas moderate and light grazing may promote progressive succession of plant species. The effects of changing climate on succession processes were not significant in the short term; a warm-humid climate is favorable to restoration of degraded vegetation, whereas a sustained warm-drought climate may result in degradation of grassland vegetation. Heavy livestock grazing should be stopped for the sustainable use of grassland; the proper grazing intensity for sandy grassland is two to three sheep or sheep equivalents per hectare in Inner Mongolia.展开更多
Background Bermudagrass(Cynodon spp.)is one of the most common perennial warm-season forages grown in the Southeastern United States.The incorporation of alfalfa(Medicago sativa)into bermudagrass pastures could serve ...Background Bermudagrass(Cynodon spp.)is one of the most common perennial warm-season forages grown in the Southeastern United States.The incorporation of alfalfa(Medicago sativa)into bermudagrass pastures could serve as an alternative source of nitrogen(N)while also improving the nutritive value of the forage base.Methods A 2-year grazing evaluation arranged in a randomized complete block design was conducted from May to September 2018(Year 1)and May–August 2019(Year 2)in Tifton,GA,USA.The objective was to compare the production of alfalfa–bermudagrass mixed pastures(BGA)with bermudagrass monoculture pastures with(BGN)or without(BG)the application of synthetic nitrogen on forage production and stocker cattle performance.Results Differences were observed for average daily gain(p=0.10),gain per hectare(p=0.02)and stocking rate(p=0.01),in that BGA was greatest compared to BGN and BG,which did not differ from each other.Furthermore,BGA had increased forage crude protein(p=0.01)and total digestible nutrients(p=0.01)compared to BGN and BG.Finally,BGA provided the greatest economic return per hectare compared to BG or BGN.Conclusions These data illustrate improved animal performance and forage nutritive value using alfalfa–bermudagrass systems and offer a viable option for producers seeking alternatives to synthetic N sources for bermudagrass pastures in the Southeastern United States.展开更多
Integrated crop-livestock system (ICLS) is an alternative that can help in intensifying food production while benefiting the environment. However, the assessments of the impacts of ICLS on the soil and economic benefi...Integrated crop-livestock system (ICLS) is an alternative that can help in intensifying food production while benefiting the environment. However, the assessments of the impacts of ICLS on the soil and economic benefits relative to specific environments in South Dakota are still lacking. This study was to assess the effects of ICLS on soil health and economic benefits under a corn (Zea mays L.)-soybean (Glycine max L.)-rye (Secale cereale L.) rotation in South Dakota. Cover crops blends were planted after the rye crop, and grazing treatments (with and without) were applied after the cover crops establishment in 2015-2016. Data from this study indicate that most soil properties are not negatively impacted by grazing. However, the grazing increased soil bulk density (BD) and decreased soil organic carbon (SOC) and soil water retention (SWR) compared with the ungrazing. The effect of grazing on corn yield was not significant. The cover crops did not impact the pH, electrical conductivity (EC), total nitrogen (TN), β-glucosidase, acid hydrolysis carbon fraction, microbial biomass carbon, and SWR, but impacted the SOC, hot/cold water carbon fraction, BD, infiltration rate (qs) in some phases and depths. The effects of different cover crop blends on corn yield were not as strong. The economic analysis showed that implementing ICLS increased the profit of the farm by $17.23 ac−1 in the first year and $43.61 ac−1 in the second year. These findings indicate that ICLS practices with proper management benefit soil health and producer income.展开更多
Fencing for grazing exclusion is regarded as a traditional and effective method for the natural restoration of degraded alpine steppe,and it effectively promotes plant growth and enhances soil carbon stocks.Arbuscular...Fencing for grazing exclusion is regarded as a traditional and effective method for the natural restoration of degraded alpine steppe,and it effectively promotes plant growth and enhances soil carbon stocks.Arbuscular mycorrhizal fungi(AMF)are essential microorganisms in grassland that play a major role in plant-derived C translocation into the soil.However,the effects of fencing on AMF communities and their contributions to soil carbon sequestration are still unclear.In this study,alpine steppe areas with three different fencing durations(free grazing,medium-term fencing for 5-6 years and long-term fencing for more than 10 years)in the northern Tibetan Plateau were selected to explore the effects of grazing exclusion on AMF communities and their roles in soil carbon sequestration.The results showed that medium-and long-term fencing significantly increased both plant aboveground biomass and soil organic carbon(SOC)content.The AMF community composition varied significantly during different fencing durations,with a dramatic increase in the relative abundance of Glomus but a significant reduction in the relative abundance of Diversispora with longer fencing time.Medium-term fencing significantly increased AMF richness and the ShannonWiener index.Meanwhile,fencing significantly increased hyphal length density(HLD),glomalin-related soil protein(GRSP)and the proportion of macroaggregates(250-2,000μm),all of which contribute positively to SOC.Structural equation modeling revealed that fencing time positively influenced HLD and the AMF community composition,subsequently affecting T-GRSP,which was tightly correlated with SOC.Our findings suggest the potentially important contribution of AMF to SOC sequestration,so more attention should be paid to AMF during alpine steppe fencing,particularly for enhancing the efficiency of degraded grassland restoration efforts.展开更多
Invasive species are increasingly spreading,particularly in rangeland ecosystems.It is essential to evaluate the effectiveness of different methods for controlling invasive plants in these ecosystems.This study aimed ...Invasive species are increasingly spreading,particularly in rangeland ecosystems.It is essential to evaluate the effectiveness of different methods for controlling invasive plants in these ecosystems.This study aimed to investigate the effects of three strategies-21-year grazing exclusion(21-YES),mowing-grazing in rotation in alternate years(MGRS),and moderate grazing(MGS)-on the change in cover,density,and biomass of Leucanthemum vulgare Lam.(Ox-eye Daisy=OED)and the plant community.To accomplish this,three sites selected for each treatment.In 2021,270 vegetation plots were sampled using a random systematic method.Subsequently,we recorded the density and canopy cover of all growth forms(forbs,grasses,and ferns),the OED biomass,and the ground cover.The results indicated that MGS reduced OED density,OED canopy,and OED biomass.Furthermore,this strategy demonstrated the highest density and canopy cover of the plant community(including total,forbs,grasses,and ferns).Additionally,the strongest correlation was observed between the total canopy and the OED density(R2=-0.91,-0.95,-0.94 in 21-YES,MGRS,and MGS,respectively),as well as between the total canopy and the OED canopy(R2=-0.51,-0.98,-0.97 in 21-YES,MGRS,and MGS,respectively).The MGS led to an increase in diversity indices.In general,the grazing strategy has proven to be effective in controlling the spread of invasive OED and has also resulted in an increase in canopy cover,density,and diversity indices of the plant community.The study highlights the importance of ongoing management efforts to control invasive species,with moderate grazing potentially serving as a more practical,culturally accepted,and costeffective short-term control strategy for widespread rangeland weed infestations.展开更多
Climate and grazing have a significant effect on vegetation structure and soil organic carbon(SOC)distribution,particularly in mountain ecosystems that are highly susceptible to climate change.However,we lack a system...Climate and grazing have a significant effect on vegetation structure and soil organic carbon(SOC)distribution,particularly in mountain ecosystems that are highly susceptible to climate change.However,we lack a systematic understanding of how vegetation structure reacts to long-term grazing disturbances,as well as the processes that influence SOC distribution.This study uses multiple sets of data spanning 20 years from a typical alpine grassland in the Qilian Mountains to investigate the effects of climate and grazing on various root-type grasses as well as the mechanisms that drive SOC distribution.We found that grazing increases the biomass of annual,biennial and perennial taproots while decreasing that of perennial rhizomes.We also found that various root-type grasses have different responses to climate and grazing.Multiple factors jointly control the variation of SOC content(SOCc),and the variation of SOC stock(SOCs)is mainly explained by the interaction between climate and grazing years.Climate and grazing can directly or indirectly affect SOCc through vegetation,and SOCs are mainly dominated by the direct effects of grazing years and grazing gradients.Grazing gradients and root-type grass biomass have a significant effect on SOC,with little effect from climate factors.Therefore,long-term grazing may affect the root-type grass and further affect SOC distribution through differences in nutrient acquisition ability and reproductive pathways.These findings provide important guidance for regulating soil carbon sequestration potential by varying the proportion of different root-type grass in the community via sowing,livestock configuration,or grazing time.展开更多
Natural grazing land plays a crucial role in extensive ruminant livestock systems,especially in semi-arid tropical regions such as East Nusa Tenggara(ENT),Indonesia.The availability and quality of forage during the dr...Natural grazing land plays a crucial role in extensive ruminant livestock systems,especially in semi-arid tropical regions such as East Nusa Tenggara(ENT),Indonesia.The availability and quality of forage during the dry season present significant challenges.This study aimed to identify variations in grass species composition and fluctuations in forage nutritional content in natural grazing lands of ENT during the dry season(July–October 2024).Sampling was conducted in four sub-districts:two representing lowland zones and two representing highland zones.In each sub-district,four grazing fields were selected,and ten plots were sampled per grazing field,totaling 160 sampling plots.Species identification and nutrient analysis included crude protein,crude fiber,energy content,and proteinenergy ratio.Statistical analyses using ANOVA and Tukey’s multiple comparison test were performed to evaluate significant differences in nutritional parameters across months and zones.Dominant species identified were Themeda arguens,Heteropogon contortus,Brachiaria decumbens,Ischaemum timorense,Cynodon dactylon,and Pennisetum clandestinum.Results showed significant monthly fluctuations in crude protein and fiber contents(p<0.05),with protein levels decreasing from July(9.31±2.66%)to October(7.53±3.10%).Energy content and protein-energy ratio also varied significantly across the dry season.A monthly shift in dominant grass species composition was observed,influenced by environmental conditions and species adaptability.The protein-energy ratio of forage remained below optimal levels throughout the dry season,potentially limiting livestock productivity.These findings provide important scientific insights for developing climate-resilient feeding strategies and support policy formulation for sustainable tropical livestock farming in semi-arid regions.展开更多
Understanding livestock performance in typical steppe ecosystems is essential for optimizing grassland-livestock interactions and minimizing environmental impact.To assess the effects of different stocking rates on th...Understanding livestock performance in typical steppe ecosystems is essential for optimizing grassland-livestock interactions and minimizing environmental impact.To assess the effects of different stocking rates on the growth performance,energy and nitrogen utilization,methane(CH_(4))emissions,and grazing behavior of Tan sheep,a 2-year grazing experiment in the typical steppe was conducted.The grazing area was divided into 9 paddocks,each 0.5 ha,with 3 spatial replicates for each stocking rate treatment(4,8,and 13 sheep per paddock),corresponding to 2.7,5.3,and 8.7 sheep ha^(–1).The results showed that the neutral detergent fiber(NDF)and acid detergent fiber(ADF)contents of herbage varied between grazing years(P<0.05),with a positive correlation between stocking rate and crude fiber content in the herbage(P<0.05).Dry matter intake(DMI)decreased with increasing stocking rate(P<0.05),and the average daily gain(ADG)was highest at 2.7 sheep ha^(–1)(P<0.05).Compared to 2.7 and 8.7 sheep ha^(–1),the5.3 sheep ha^(–1)treatment exhibited the lowest nutrient digestibility for dry matter,nitrogen,and ether extract(P<0.05).Fecal nitrogen was lowest at 8.7 sheep ha^(–1)(P<0.05),while retained nitrogen as a proportion of nitrogen intake was highest.Digestive energy(DE),metabolic energy(ME),and the ratios of DE to gross energy(GE)and ME to GE were highest at 8.7 sheep ha^(–1)(P<0.05).In contrast,CH_4 emissions,CH_4 per DMI,and CH_(4)E as a proportion of GE were highest at 2.7 sheep ha^(–1)(P<0.05).Stocking rate and grazing year did not significantly affect rumen fermentation parameters,including volatile fatty acids,acetate,propionate,and the acetate/propionate ratio.At 8.7sheep ha^(–1),daily grazing time and inter-individual distance increased,while time allocated to grazing,walking,and ruminating/resting decreased as stocking rates increased(P<0.05).This study highlights the importance of adjusting stocking rates based on the nutritional value of forage and grazing year to optimize grazing management.展开更多
Grazing management significantly influences greenhouse gas(GHG)emissions and the global warming potential(GWP)in grasslands.Yet,a limited understanding of the impact of grazing and grazing exclusion on GHG emis-sions ...Grazing management significantly influences greenhouse gas(GHG)emissions and the global warming potential(GWP)in grasslands.Yet,a limited understanding of the impact of grazing and grazing exclusion on GHG emis-sions and GWP in grasslands hinders progress towards grassland ecosystem sustainability and GHG mitigation.We conducted a global meta-analysis of 75 published studies to investigate the effects of grazing and grazing exclusion on methane(CH_(4)),carbon dioxide(CO_(2)),nitrous oxide(N_(2 )O),and GWP.Our results revealed that grazing and grazing exclusion significantly increased the CO_(2) and CH4 emissions,respectively.The responses of GHG emissions and GWP to grazing were regulated by grazing intensity and elevation.We also found that light grazing significantly decreased GWP but heavy grazing increased GWP.Reducing grazing intensity was a simple and effective method through stocking rate adjustment,which promised a large GHG mitigation poten-tial.Our results demonstrated that GHG emissions increased with elevation under grassland grazing,implying that irrational grazing in high-elevation grasslands promoted GHG emissions.In comparison with grazing,only long-term grazing exclusion reduced the GWP,and CH4 emissions enhanced with grazing exclusion duration.However,long-term grazing exclusion may shift economic demand and grazing burden to other areas.Overall,we suggested that regulating the grazing intensity,rather than grazing exclusion,was an effective way to re-duce GHG emissions.Our study contributed to the enhancement of sustainable grazing management practices for GHG balance and GWP in global grasslands,and offered a global picture for understanding the changes in GHG emissions and GWP under different grazing management regimes.展开更多
Microzoopiankton community composition in the north of South China Sea was investigated during autumn （between September and October）, 2004. Dilution technique using chlorophyll a （Chl a） was employed to estimate ...Microzoopiankton community composition in the north of South China Sea was investigated during autumn （between September and October）, 2004. Dilution technique using chlorophyll a （Chl a） was employed to estimate grazing rates and grazing pressure. The results showed that Polymenophorea Oligotrichida was the dominant group with 16 species, and there were 4 species in Oligotrichina and 11 species in Tintinnina. The ciliates abundance ranged from 9 to 102 ind/m^3, instantaneous growth rates of phytoplankton （k） varied from 0.03 / d to 2.13 / d. Grazing rates of microzooplankton（g） ranged between 0.01 / d and 1.06 / d. The grazing pressure on initial phytoplankton stock （Pi） and primary production （Pp） was 0.089 % - 65.23 % and 33.63 % - 86.04 %, respectively. The grazing of microzooplankton was mainly limited by ciliates abundance. Results of grazing pressure on primary production indicated that microzooplankton played an improtant role in transmitting primary production in the north of South China Sea.展开更多
[Objective] This study was conducted to explore the mechanism of physi- ological adaptation of Agropyron cristatum under grazing pressure, and to provide a theoretical basis for the protection and rational utilization...[Objective] This study was conducted to explore the mechanism of physi- ological adaptation of Agropyron cristatum under grazing pressure, and to provide a theoretical basis for the protection and rational utilization of forage resources, breeding and introduction of high-quality forage materials. [Method] The mature leaves of upper parts of A. cristatum plants in grazed and non-grazed areas were collected at tillering （late May）, heading （late June）, flowering （late July） and seed maturity （late August） stages for determination of superoxide dismutase （SOD）, peroxidase （POD） activities and malondialdehyde （MDA） content. [Result] The MDA content of grazing population was higher than that of non-grazing population throughout the whole growth period of A. cristatum. The SOD activity was significantly increased from heading to flowering stage but was rapidly reduced at seed maturity stage, with no significant difference between grazing and non-grazing populations of A. cristatum. The POD activity kept increasing from heading stage, and it was higher of grazing population than that of non-grazing population. [Conclusion] The MDA content in leaves of A. cristatum was increased under grazing pressure, leading to increased membrane lipid oxidation; POD played an important role in removal of the free radicals those accumulated in A. cristatum under grazing pressure.展开更多
By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazi...By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazing pressure. How- ever, the contents of free glycine （Gly） and proline （Pro） were very sensitive to grazing. Glycine content in grazing population was higher than that in non-grazing population at flowering stage; the content of free proline in non-grazing population was higher than that in grazing population at tillering, heading and especially flower- ing stage; the content of free proline under grazing pressure at maturity stage was higher than that of non-grazing population.展开更多
基金Demonstration of Grass Digital Monitoring,Control and Decision-making Techniques (2008GB23260400)Recovery of Degraded Vegetation in Inner Mongolia and Directed Economic Plants Industrial Growing Base,the Research of Forage Yield Remote Sensing Estimation and Carrying Capacity in Hulunbeir Grassland,the National high Technology Research and Development Program of China(2006AA10Z241)+1 种基金National Science and Technology Support Program (2006BAC01A12,2006BAD16B05-2)Modern Agricultural Technology System of Special Funding
文摘We studied a soil seed bank in the Stipa breviflora desert steppe under three grassland management systems, namely continuous grazing, rotational grazing, and no grazing, from 1999 until 2007. The germinable seed bank species in rotational, continuous and no gazing were 11, 9 and 8 species, respectively. Rotational grazing increased the number of seed bank plant species and perenni- al grasses. The density of germinal soil seed bank was significantly higher in the enclosed area （19,533.33 seeds/m2） than those in rotational （3,233.33 seeds/mz） and continuous grazing areas （2,553.60 seeds/m2）. The vertical distribution of the soil seed bank had a similar trend： 75.06%-83.19% of the seeds are distributed in the top 0-5 cm soil layer, 14.16%-21.68% in the 5-10 cm lay- er, and 2.65%-4.95% in the 10-15 cm layer, which varied between the grazing treatments. Density of the soil seed bank was sig- nificantly higher in the enclosed area, and there was no significant difference between rotational and continuous grazing. The Margalef and Shannon-Wiener indices for the soil seed bank were higher for rotational grazing treatment than for continuous grazing. The Sorensen＇s similarity index for the soil seed bank between the enclosed and rotational grazing areas reached 0.857.
基金funded by basic special funding from the central public welfare scientific research institutes (No.202-21)public sector projects in the Ministry of Agriculture(Nos. 201003019,201003061)scientific and technological innovation and incentive funds of Inner Mongolia autonomous region and major state basic research development program of China (973 Program) (2010CB833502)
文摘This study investigated the effects of various grazing systems, including continuous grazing, rotational grazing, and no-grazing systems, on the community biomass in the Stipa breviflora Griseb desert grassland during the grazing seasons in 2005, 2006, and 2007, based on study sites established in 1999. We found that the seasonal dynamics of the aboveground biomass were quite similar among the three treatments, which reached peak values in period from August to September during each study year. The continuous grazing system reduced the aboveground biomass from 2005 to 2007 under drought conditions, and the rotational grazing and no-grazing systems maintained more aboveground biomass than the continuous grazing system did. The belowground biomass declined with the increase of soil depth among the three treatments, and in the surface 20-cm soil layer it accounted for more than 60% of the total biomass. The belowground biomass was found to be highly correlated with soil depth under rotational grazing. The total belowground biomass within the 0--100-cm soil layer for rotational grazing was sig- nificantly higher than for continuous grazing and no-grazing, and had 15,775 kg/ha more biomass. Our results demonstrate that conservative rotational grazing can alleviate grassland deterioration by reserving more aboveground and belowground biomass than the continuous grazing system does.
基金DairyNZ,Grant/Award Number:Plantain Potency and Practice ProgrammeMinistry for Primary Industries,Grant/Award Number:SFFF Partnership Agreement 19047。
文摘Forage plantain(Plantago lanceolata L.)has emerged as a valuable agronomic species within grazing systems in New Zealand.The release of two cultivars in New Zealand in the mid‐1990s led to on‐farm use and research.Subsequent identification of the potential of plantain for reducing nitrogen losses from intensive grazing systems led to an expansion of research and extension over the last decade.This review summarises key aspects of the agronomic use of modern forage plantain from mainly New Zealand‐based research,including environmental tolerance,forage productivity,feed quality,cultivar development,weed and pest management,grazing management and measurement of herbage mass.The agronomic advantages of including modern plantain cultivars in pastures include seasonal growth complementarity with grasses and clovers,greater summer‐drought resilience and improved forage quality.On‐farm use of plantain in New Zealand has grown to about 20%of new pastures over three decades,a modest level which can be attributed to unmet farmer expectations of plantain persistence as a substantive contributor to perennial grass‐based swards and the limitations for controlling dicot weeds.These are key areas of future research priority,along with the potential for complementarity with forage grasses other than perennial ryegrass.
基金supported by the National Key Research and Development Program of China(2024YFF1306305)the Inner Mongolia Autonomous Region Natural Science Foundation Project(2025QN03106)+1 种基金the Research Start-up Project for the Introduction of High-level and Outstanding Doctoral Talent at Inner Mongolia Agricultural University(NDYB2024-42)the National Natural Science Foundation of China(42201012).
文摘Global grassland degradation necessitates the identification of sustainable grazing management strategies.In semi-arid regions,grazing exclusion(GE),cold-season grazing(CG),and free grazing(FG)represent common practices in grassland ecosystems,yet the long-term ecological consequences of these patterns on plant community structure and soil aggregate stability remain inadequately elucidated.In this study,we evaluated the effects of GE,CG,and FG on soil organic carbon,soil water content,soil bulk density,soil aggregates,and vegetation indicators in Xilamuren steppe,a semi-arid grassland in northern China through field sampling and laboratory analyses in 2024.Our findings revealed that,compared to CG and FG,GE significantly enhanced aboveground and belowground biomass,species diversity,and soil physical-chemical properties in the 0–30 cm layer.The dominant plant species in GE and CG sites were Stipa krylovii,Leymus chinensis,and Agropyron cristatum,whereas Stipa krylovii,Artemisia frigida,and Leymus chinensis were predominant in FG site.Different grazing patterns led to distinct soil aggregate distributions,with>2.00 and<0.25 mm aggregates exhibiting the highest content in different soil layers depending on the grazing patterns.All grazing management strategies significantly improved soil aggregate stability,with the overall stability following the order:GE>CG>FG.Furthermore,random forest modeling identified plant species diversity,plant growth traits,and grazing patterns as the primary determinants of soil aggregate stability.Collectively,these results offer valuable insights into the sustainable management and ecological restoration of semi-arid grasslands under different grazing pressures.
基金supported by the Universidad Nacional de Río Negro(PI-UNRN 40C-1088)the Consejo Nacional de Investigaciones Científicas y Técnicas(PIP-CONICET 2023-402).
文摘The connection between climatic factors and grazing is essential for maintaining ecosystem function and vegetation productivity.This study examined the impact of grazing intensity on vegetation across a broad climatic gradient spanning the Espinal,Argentine Low Monte,and Patagonian Steppe ecoregions of Argentina.The research was carried out at eight sampling sites with radial grazing gradients generated around artificial water sources(piospheres),exhibiting two contrasting response patterns of vegetation to grazing pressure.One of the response patterns shows a typical vegetation response to grazing that the vegetation productivity increases with the distance to the water sources(decreasing grazing intensity).The second pattern is found in drier regions,where vegetation presents an inverse productivity response that vegetation productivity is higher near water sources(high grazing intensity)due to increased shrub cover.Vegetation productivity was measured using the Normalized Difference Vegetation Index(NDVI).Vegetation patch structure and cover were determined for each site with high,medium,and low grazing intensities.Results indicated that shrub cover is the primary driver of vegetation productivity,showing contrasting responses to grazing intensity between the two identified patterns.While NDVI proved to be a reliable proxy for shrub cover and total vegetation cover(R2>0.70),it failed to reflect grass cover dynamics.Furthermore,mean annual temperature was more strongly correlated with vegetation cover changes,while grazing intensity significantly altered vegetation patch structure and soil cover distribution.Specifically,in drier regions,high grazing intensity led to larger patches while,in wetter regions,it led to smaller patches(fragmentation).Shrubs,with their deeper roots and drought tolerance,were less preferred and more resistant to grazing in arid environments and thrived under grazing pressure in these arid conditions.Our results underscored the need for adaptive management strategies in grazing systems.Traditional approaches may require significant adjustments,as the efficacy of management hinges on the interplay of specific climatic conditions and the varied responses of vegetation.Furthermore,effective conservation efforts should prioritize the recognition and protection of shrubs given their critical contribution to ecosystem function and biodiversity.Ultimately,this research provides a valuable framework to understand the complex dynamics between grazing and vegetation in arid and semi-arid environments,highlighting that sustainable grazing practices should be tailored to account for both climatic variables and the unique characteristics of different plant communities.
基金financially supported by the Science and Technology Bureau of Ali Prefecture,project named“Assessing the Carbon Sequestration and Carbon Sink Enhancement Potential of Natural Ecosystems in Ali Region(QYXTZX-AL2022-05)”。
文摘The alpine grassland vegetation on the Qinghai-Tibet Plateau is composed of plant patches in varied sizes.It remains uncertain whether vegetation recovery following grazing exclusion(GE)in degraded grasslands is driven by increases in patches number(NP),patch size(PS),or both.We based our predictions on two hypotheses:GE intensifies plant competition,and facilitation prevails near patches while competition prevails in interpatch spaces.We predicted that the NP would remain stable or decrease and PS would increase under GE treatment.To evaluate these predictions,we conducted a study in six lightly degraded alpine grasslands under free grazing(FG)conditions in Bangor County,Xizang Autonomous Region,China,with corresponding GE treatments using transects in 2017 and 2018.Results revealed that four sites in 2017 and five sites in 2018 had reduced NP and increased PS,with probabilities of 0.033(2017)and 0.004(2018),respectively,and a joint probability of 0.0001 under the null hypothesis that GE does not affect NP or PS.The NP reduction was solely due to the decrease in small patch sizes.An increase in PS was common across species,and a predominant tendency for NP reduction was observed among species across the sites.The overall changes in NP and PS were primarily driven by the three most abundant species(contributing more than 60%in both years),rather than by shifts in floristic composition.Our findings highlight that vegetation recovery in Bangor alpine steppes following GE relies solely on the expansion of existing patches rather than the recruitment of new ones in interpatch gaps.We recommend prioritizing growth-promoting measures,such as nutrient or water management,over seed addition when assisting with GE for restoring lightly degraded grasslands.
基金co-supported by the National Natural Science Foundation of China(No.52206039)the Taihang Laboratory of China(No.A2053)+1 种基金the Aeronautical Science Foundation of China(No.20240011051001)the National Key R&D Program of China(No.2021YFB3703900)。
文摘Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF septum liner and its impedance model on the Beihang Grazing Flow Duct(BGFD)setup,over a wide frequency range under grazing flows up to 0.5 Mach number and Sound Pressure Level(SPL)up to 150 dB,typically encountered in aeroengine nacelles.Several specimens varying in the numbers,types,and depths of septa among units are designed,fabricated,and measured.Their impedances and Transmission Losses(TL)are obtained using the mirror-based multimodal straightforward method and the mode decomposition technique,respectively.Generally,the model predictions show good agreement with the educed impedances in all cases,and such liners with a large-porosity facesheet exhibit low acoustic nonlinearities in the presence of high SPL,especially under high-velocity grazing flows.Moreover,a MDOF liner we delicately designed,compared with a conventional broadband three-layer perforated liner as the reference,is close to the resonant state at more frequencies and thus has higher and wider measured TL spectra almost from 1 kHz up to 10 kHz at studied Mach numbers,under the premise of saving 22.7 mm in the thickness.These show that,the MDOF septum liner,if well designed,can achieve an ultra-broadband efficient sound attenuation using more limited spaces in complex aeroacoustic environments.
基金Project supported by the National Natural Science Foundation of China(Grant No.61104040)the Natural Science Foundation of Hebei Province,China(Grant No.E2012203090)the University Innovation Team of Hebei Province Leading Talent Cultivation Project,China(Grant No.LJRC013)
文摘Grazing bifurcation of a relative rotation system with backlash non-smooth characteristic is studied along with the change of the external excitation in this paper. Considering the oil film, backlash, time-varying stiffness and time-varying error, the dynamical equation of a relative rotation system with a backlash non-smooth characteristic is deduced by applying the elastic hydrodynamic lubrication（EHL） and the Grubin theories. In the process of relative rotation, the occurrence of backlash will lead to the change of dynamic behaviors of the system, and the system will transform from the meshing state to the impact state. Thus, the zero-time discontinuous mapping（ZDM） and the Poincare mapping are deduced to analyze the local dynamic characteristics of the system before as well as after the moment that the backlash appears（i.e.,the grazing state）. Meanwhile, the grazing bifurcation mechanism is analyzed theoretically by applying the impact and Floquet theories. Numerical simulations are also given, which confirm the analytical results.
基金funded by a Chinese National Key Project for Basic Scientific Research (2009CB421303)a Chinese National Fund Project (30972422)
文摘To understand the effects of grazing activities and climate change on sandy grassland ecosystems in northem China, a livestock field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land, Inner Mongolia. The results showed that sustained heavy grazing resulted in serious degradation of the vegetation; moderate grazing can maintain vegetation stabilization; and light grazing can promote rapid restoration of degraded vegetation. The livestock productivity was the highest in the moderate grazing grassland, and sustained heavy grazing resulted in rapid decrease of the livestock productivity. Heavy grazing can cause a retrogressive succession of grassland vegetation, whereas moderate and light grazing may promote progressive succession of plant species. The effects of changing climate on succession processes were not significant in the short term; a warm-humid climate is favorable to restoration of degraded vegetation, whereas a sustained warm-drought climate may result in degradation of grassland vegetation. Heavy livestock grazing should be stopped for the sustainable use of grassland; the proper grazing intensity for sandy grassland is two to three sheep or sheep equivalents per hectare in Inner Mongolia.
文摘Background Bermudagrass(Cynodon spp.)is one of the most common perennial warm-season forages grown in the Southeastern United States.The incorporation of alfalfa(Medicago sativa)into bermudagrass pastures could serve as an alternative source of nitrogen(N)while also improving the nutritive value of the forage base.Methods A 2-year grazing evaluation arranged in a randomized complete block design was conducted from May to September 2018(Year 1)and May–August 2019(Year 2)in Tifton,GA,USA.The objective was to compare the production of alfalfa–bermudagrass mixed pastures(BGA)with bermudagrass monoculture pastures with(BGN)or without(BG)the application of synthetic nitrogen on forage production and stocker cattle performance.Results Differences were observed for average daily gain(p=0.10),gain per hectare(p=0.02)and stocking rate(p=0.01),in that BGA was greatest compared to BGN and BG,which did not differ from each other.Furthermore,BGA had increased forage crude protein(p=0.01)and total digestible nutrients(p=0.01)compared to BGN and BG.Finally,BGA provided the greatest economic return per hectare compared to BG or BGN.Conclusions These data illustrate improved animal performance and forage nutritive value using alfalfa–bermudagrass systems and offer a viable option for producers seeking alternatives to synthetic N sources for bermudagrass pastures in the Southeastern United States.
文摘Integrated crop-livestock system (ICLS) is an alternative that can help in intensifying food production while benefiting the environment. However, the assessments of the impacts of ICLS on the soil and economic benefits relative to specific environments in South Dakota are still lacking. This study was to assess the effects of ICLS on soil health and economic benefits under a corn (Zea mays L.)-soybean (Glycine max L.)-rye (Secale cereale L.) rotation in South Dakota. Cover crops blends were planted after the rye crop, and grazing treatments (with and without) were applied after the cover crops establishment in 2015-2016. Data from this study indicate that most soil properties are not negatively impacted by grazing. However, the grazing increased soil bulk density (BD) and decreased soil organic carbon (SOC) and soil water retention (SWR) compared with the ungrazing. The effect of grazing on corn yield was not significant. The cover crops did not impact the pH, electrical conductivity (EC), total nitrogen (TN), β-glucosidase, acid hydrolysis carbon fraction, microbial biomass carbon, and SWR, but impacted the SOC, hot/cold water carbon fraction, BD, infiltration rate (qs) in some phases and depths. The effects of different cover crop blends on corn yield were not as strong. The economic analysis showed that implementing ICLS increased the profit of the farm by $17.23 ac−1 in the first year and $43.61 ac−1 in the second year. These findings indicate that ICLS practices with proper management benefit soil health and producer income.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program,China(2019QZKK0304)the National Natural Science Foundation of China(31800380 and 31761123001-1)。
文摘Fencing for grazing exclusion is regarded as a traditional and effective method for the natural restoration of degraded alpine steppe,and it effectively promotes plant growth and enhances soil carbon stocks.Arbuscular mycorrhizal fungi(AMF)are essential microorganisms in grassland that play a major role in plant-derived C translocation into the soil.However,the effects of fencing on AMF communities and their contributions to soil carbon sequestration are still unclear.In this study,alpine steppe areas with three different fencing durations(free grazing,medium-term fencing for 5-6 years and long-term fencing for more than 10 years)in the northern Tibetan Plateau were selected to explore the effects of grazing exclusion on AMF communities and their roles in soil carbon sequestration.The results showed that medium-and long-term fencing significantly increased both plant aboveground biomass and soil organic carbon(SOC)content.The AMF community composition varied significantly during different fencing durations,with a dramatic increase in the relative abundance of Glomus but a significant reduction in the relative abundance of Diversispora with longer fencing time.Medium-term fencing significantly increased AMF richness and the ShannonWiener index.Meanwhile,fencing significantly increased hyphal length density(HLD),glomalin-related soil protein(GRSP)and the proportion of macroaggregates(250-2,000μm),all of which contribute positively to SOC.Structural equation modeling revealed that fencing time positively influenced HLD and the AMF community composition,subsequently affecting T-GRSP,which was tightly correlated with SOC.Our findings suggest the potentially important contribution of AMF to SOC sequestration,so more attention should be paid to AMF during alpine steppe fencing,particularly for enhancing the efficiency of degraded grassland restoration efforts.
基金the University of Mohaghegh Ardabili,Department of Natural Resources,Iran for financial support。
文摘Invasive species are increasingly spreading,particularly in rangeland ecosystems.It is essential to evaluate the effectiveness of different methods for controlling invasive plants in these ecosystems.This study aimed to investigate the effects of three strategies-21-year grazing exclusion(21-YES),mowing-grazing in rotation in alternate years(MGRS),and moderate grazing(MGS)-on the change in cover,density,and biomass of Leucanthemum vulgare Lam.(Ox-eye Daisy=OED)and the plant community.To accomplish this,three sites selected for each treatment.In 2021,270 vegetation plots were sampled using a random systematic method.Subsequently,we recorded the density and canopy cover of all growth forms(forbs,grasses,and ferns),the OED biomass,and the ground cover.The results indicated that MGS reduced OED density,OED canopy,and OED biomass.Furthermore,this strategy demonstrated the highest density and canopy cover of the plant community(including total,forbs,grasses,and ferns).Additionally,the strongest correlation was observed between the total canopy and the OED density(R2=-0.91,-0.95,-0.94 in 21-YES,MGRS,and MGS,respectively),as well as between the total canopy and the OED canopy(R2=-0.51,-0.98,-0.97 in 21-YES,MGRS,and MGS,respectively).The MGS led to an increase in diversity indices.In general,the grazing strategy has proven to be effective in controlling the spread of invasive OED and has also resulted in an increase in canopy cover,density,and diversity indices of the plant community.The study highlights the importance of ongoing management efforts to control invasive species,with moderate grazing potentially serving as a more practical,culturally accepted,and costeffective short-term control strategy for widespread rangeland weed infestations.
基金funded by the China National Natural Science Foundation(32161143028)National Science and Technology Assistance(KY202002011)the Innovative Research Team of the Ministry of Education(IRT_17R50).
文摘Climate and grazing have a significant effect on vegetation structure and soil organic carbon(SOC)distribution,particularly in mountain ecosystems that are highly susceptible to climate change.However,we lack a systematic understanding of how vegetation structure reacts to long-term grazing disturbances,as well as the processes that influence SOC distribution.This study uses multiple sets of data spanning 20 years from a typical alpine grassland in the Qilian Mountains to investigate the effects of climate and grazing on various root-type grasses as well as the mechanisms that drive SOC distribution.We found that grazing increases the biomass of annual,biennial and perennial taproots while decreasing that of perennial rhizomes.We also found that various root-type grasses have different responses to climate and grazing.Multiple factors jointly control the variation of SOC content(SOCc),and the variation of SOC stock(SOCs)is mainly explained by the interaction between climate and grazing years.Climate and grazing can directly or indirectly affect SOCc through vegetation,and SOCs are mainly dominated by the direct effects of grazing years and grazing gradients.Grazing gradients and root-type grass biomass have a significant effect on SOC,with little effect from climate factors.Therefore,long-term grazing may affect the root-type grass and further affect SOC distribution through differences in nutrient acquisition ability and reproductive pathways.These findings provide important guidance for regulating soil carbon sequestration potential by varying the proportion of different root-type grass in the community via sowing,livestock configuration,or grazing time.
基金supported by the Ministry of Education,Culture,Research,and Technology of the Republic of Indonesia through the Directorate of Research,Technology,and Community Service under the Primary Contract Number:073/E5/PG.02.00.PL/2024 and the Secondary Contract Number:432/UN15.22/SP2H/PL/2024.
文摘Natural grazing land plays a crucial role in extensive ruminant livestock systems,especially in semi-arid tropical regions such as East Nusa Tenggara(ENT),Indonesia.The availability and quality of forage during the dry season present significant challenges.This study aimed to identify variations in grass species composition and fluctuations in forage nutritional content in natural grazing lands of ENT during the dry season(July–October 2024).Sampling was conducted in four sub-districts:two representing lowland zones and two representing highland zones.In each sub-district,four grazing fields were selected,and ten plots were sampled per grazing field,totaling 160 sampling plots.Species identification and nutrient analysis included crude protein,crude fiber,energy content,and proteinenergy ratio.Statistical analyses using ANOVA and Tukey’s multiple comparison test were performed to evaluate significant differences in nutritional parameters across months and zones.Dominant species identified were Themeda arguens,Heteropogon contortus,Brachiaria decumbens,Ischaemum timorense,Cynodon dactylon,and Pennisetum clandestinum.Results showed significant monthly fluctuations in crude protein and fiber contents(p<0.05),with protein levels decreasing from July(9.31±2.66%)to October(7.53±3.10%).Energy content and protein-energy ratio also varied significantly across the dry season.A monthly shift in dominant grass species composition was observed,influenced by environmental conditions and species adaptability.The protein-energy ratio of forage remained below optimal levels throughout the dry season,potentially limiting livestock productivity.These findings provide important scientific insights for developing climate-resilient feeding strategies and support policy formulation for sustainable tropical livestock farming in semi-arid regions.
基金supported by the National Natural Science Foundation of China(32161143028)the Key Technology of Grassland Ecological Civilization Demonstration Area in Ningxia Hui Autonomous Region,China(20210239)the Northwest Shelterbelt Construction Bureau of the National Forestry and Grassland Administration,China。
文摘Understanding livestock performance in typical steppe ecosystems is essential for optimizing grassland-livestock interactions and minimizing environmental impact.To assess the effects of different stocking rates on the growth performance,energy and nitrogen utilization,methane(CH_(4))emissions,and grazing behavior of Tan sheep,a 2-year grazing experiment in the typical steppe was conducted.The grazing area was divided into 9 paddocks,each 0.5 ha,with 3 spatial replicates for each stocking rate treatment(4,8,and 13 sheep per paddock),corresponding to 2.7,5.3,and 8.7 sheep ha^(–1).The results showed that the neutral detergent fiber(NDF)and acid detergent fiber(ADF)contents of herbage varied between grazing years(P<0.05),with a positive correlation between stocking rate and crude fiber content in the herbage(P<0.05).Dry matter intake(DMI)decreased with increasing stocking rate(P<0.05),and the average daily gain(ADG)was highest at 2.7 sheep ha^(–1)(P<0.05).Compared to 2.7 and 8.7 sheep ha^(–1),the5.3 sheep ha^(–1)treatment exhibited the lowest nutrient digestibility for dry matter,nitrogen,and ether extract(P<0.05).Fecal nitrogen was lowest at 8.7 sheep ha^(–1)(P<0.05),while retained nitrogen as a proportion of nitrogen intake was highest.Digestive energy(DE),metabolic energy(ME),and the ratios of DE to gross energy(GE)and ME to GE were highest at 8.7 sheep ha^(–1)(P<0.05).In contrast,CH_4 emissions,CH_4 per DMI,and CH_(4)E as a proportion of GE were highest at 2.7 sheep ha^(–1)(P<0.05).Stocking rate and grazing year did not significantly affect rumen fermentation parameters,including volatile fatty acids,acetate,propionate,and the acetate/propionate ratio.At 8.7sheep ha^(–1),daily grazing time and inter-individual distance increased,while time allocated to grazing,walking,and ruminating/resting decreased as stocking rates increased(P<0.05).This study highlights the importance of adjusting stocking rates based on the nutritional value of forage and grazing year to optimize grazing management.
基金supported by National Natural Science Foundation of China(Grant No.72394401).
文摘Grazing management significantly influences greenhouse gas(GHG)emissions and the global warming potential(GWP)in grasslands.Yet,a limited understanding of the impact of grazing and grazing exclusion on GHG emis-sions and GWP in grasslands hinders progress towards grassland ecosystem sustainability and GHG mitigation.We conducted a global meta-analysis of 75 published studies to investigate the effects of grazing and grazing exclusion on methane(CH_(4)),carbon dioxide(CO_(2)),nitrous oxide(N_(2 )O),and GWP.Our results revealed that grazing and grazing exclusion significantly increased the CO_(2) and CH4 emissions,respectively.The responses of GHG emissions and GWP to grazing were regulated by grazing intensity and elevation.We also found that light grazing significantly decreased GWP but heavy grazing increased GWP.Reducing grazing intensity was a simple and effective method through stocking rate adjustment,which promised a large GHG mitigation poten-tial.Our results demonstrated that GHG emissions increased with elevation under grassland grazing,implying that irrational grazing in high-elevation grasslands promoted GHG emissions.In comparison with grazing,only long-term grazing exclusion reduced the GWP,and CH4 emissions enhanced with grazing exclusion duration.However,long-term grazing exclusion may shift economic demand and grazing burden to other areas.Overall,we suggested that regulating the grazing intensity,rather than grazing exclusion,was an effective way to re-duce GHG emissions.Our study contributed to the enhancement of sustainable grazing management practices for GHG balance and GWP in global grasslands,and offered a global picture for understanding the changes in GHG emissions and GWP under different grazing management regimes.
文摘Microzoopiankton community composition in the north of South China Sea was investigated during autumn （between September and October）, 2004. Dilution technique using chlorophyll a （Chl a） was employed to estimate grazing rates and grazing pressure. The results showed that Polymenophorea Oligotrichida was the dominant group with 16 species, and there were 4 species in Oligotrichina and 11 species in Tintinnina. The ciliates abundance ranged from 9 to 102 ind/m^3, instantaneous growth rates of phytoplankton （k） varied from 0.03 / d to 2.13 / d. Grazing rates of microzooplankton（g） ranged between 0.01 / d and 1.06 / d. The grazing pressure on initial phytoplankton stock （Pi） and primary production （Pp） was 0.089 % - 65.23 % and 33.63 % - 86.04 %, respectively. The grazing of microzooplankton was mainly limited by ciliates abundance. Results of grazing pressure on primary production indicated that microzooplankton played an improtant role in transmitting primary production in the north of South China Sea.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201003023)~~
文摘[Objective] This study was conducted to explore the mechanism of physi- ological adaptation of Agropyron cristatum under grazing pressure, and to provide a theoretical basis for the protection and rational utilization of forage resources, breeding and introduction of high-quality forage materials. [Method] The mature leaves of upper parts of A. cristatum plants in grazed and non-grazed areas were collected at tillering （late May）, heading （late June）, flowering （late July） and seed maturity （late August） stages for determination of superoxide dismutase （SOD）, peroxidase （POD） activities and malondialdehyde （MDA） content. [Result] The MDA content of grazing population was higher than that of non-grazing population throughout the whole growth period of A. cristatum. The SOD activity was significantly increased from heading to flowering stage but was rapidly reduced at seed maturity stage, with no significant difference between grazing and non-grazing populations of A. cristatum. The POD activity kept increasing from heading stage, and it was higher of grazing population than that of non-grazing population. [Conclusion] The MDA content in leaves of A. cristatum was increased under grazing pressure, leading to increased membrane lipid oxidation; POD played an important role in removal of the free radicals those accumulated in A. cristatum under grazing pressure.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201003023)~~
文摘By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazing pressure. How- ever, the contents of free glycine （Gly） and proline （Pro） were very sensitive to grazing. Glycine content in grazing population was higher than that in non-grazing population at flowering stage; the content of free proline in non-grazing population was higher than that in grazing population at tillering, heading and especially flower- ing stage; the content of free proline under grazing pressure at maturity stage was higher than that of non-grazing population.
