While substantial nitrogen(N)input from yak urine in intensively grazed grasslands on the Qinghai-Tibetan Plateau(QTP)is well documented,the species-specific responses of dominant forage plants-particularly regarding ...While substantial nitrogen(N)input from yak urine in intensively grazed grasslands on the Qinghai-Tibetan Plateau(QTP)is well documented,the species-specific responses of dominant forage plants-particularly regarding N uptake efficiency,environmental impacts,and associated microbial dynamics-remain poorly understood.This study investigated Elymus nutans(Gramineae)and Kobresia graminifolia(Cyperaceae),two ecologically dominant species,to elucidate the divergent nitrogen transformation features under urine deposition.During the growing season,we simulated yak urine input by applying 640 mL urine per 40 cm×40 cm patch in natural grasslands.Over six weeks,we measured total plant N uptake and soil nitrous oxide(N_(2)O)emissions and evaluated soil nitrification rates through a 2-week indoor incubation experiment.To elucidate the underlying microbial mechanisms,we analysed the abundance and composition of rhizosphere ammonia-oxidizing archaea(AOA)and bacteria(AOB).Results showed that K.graminifolia exhibited significantly lower soil nitrification rates and N_(2)O emissions but higher total N uptake compared to E.nutans.Furthermore,K.graminifolia soil had lower AOB and higher AOA abundances.Specifically,the relative abundances of Nitrosophaera and Candidatus Nitrosocosmicus within AOA,as well as Nitrosovibrio and Nitrosomonas within AOB,were higher in K.graminifolia soil.These findings indicate that variations in nitrifier populations may be key drivers of differences in N uptake and N_(2)O emissions across dominant forage species.This study provides valuable insights for developing effective management strategies for intensively grazed grasslands on the QTP.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
Changes in soil organic carbon(SOC) in rangelands has been extensively investigated. Grazing in outlying rangeland areas has caused severe impacts on ecosystem functions. To reveal the effects of grazing on SOC, we ev...Changes in soil organic carbon(SOC) in rangelands has been extensively investigated. Grazing in outlying rangeland areas has caused severe impacts on ecosystem functions. To reveal the effects of grazing on SOC, we evaluated the grassland in Xilin Gol League, Inner Mongolia, China. Grazing intensity was determined by using two image sets of vegetation index with normalized differences in grazing periods(July 12 th and 28th). The range of variation in vegetation index was then used to measure the grazing intensity. The SOC storage and density were obtained by conducting experiments on field soil samples. Results showed that 1) the grazing intensity in Xilin Gol League declined gradually from west to east; by contrast, the spatial distribution of SOC density increased gradually. 2) As grazing intensity increased, the carbon storage of rangeland decreased evidently. Minimum carbon storage was observed in grasslands classified under extreme overgrazing; by comparison, maximum values were found in areas classified under light overgrazing to moderate grazing. 3) The estimated soil carbon storage was 8.48 × 10^(11) kg, and the average carbon density was 4.08 kg/m^2. Our research demonstrated that grazing intensity likely affects soil carbon. Moderate grazing is an optimum strategy to maintain carbon storage and ensure sustainable grassland utilization.展开更多
Ammonia （NH3） emission and redeposition play a major role in terrestrial nitrogen （N） cycles and can also cause environmental problems, such as changes in biodiversity, soil acidity, and eutrophication. Previous f...Ammonia （NH3） emission and redeposition play a major role in terrestrial nitrogen （N） cycles and can also cause environmental problems, such as changes in biodiversity, soil acidity, and eutrophication. Previous field grazing experiments showed inconsistent （positive, neutral, and negative） NH3 volatilization from soils in response to varying grazing intensities. However, it remains unclear whether, or to what extent, NH3 emissions from soil are affected by increasing grazing intensities in Inner Mongolian grasslands. Using a 5-year grazing experiment, we investigated the relationship between NH3 volatilization from soil and grazing pressure （0.0, 3.0, 6.0, and 9.0 sheep/hm2） from June to September of 2009 and 2010 via the vented-chamber method. The results show that soil NH3 volatilization was not significantly different at different grazing intensities in 2009, although it was higher at the highest stocking rate during 2010. There was no significant linear relationship between soil NH3 volatilization rates and soil NH4^-N, but soil NH3 volatilization rates were significantly related to soil water content and air temperature. Grazing intensities had no significant influence on soil NH3 volatilization. Soil NH3 emissions from June to Sep- tember （grazing period）, averaged over all grazing intensities, were 9.6±0.2 and 19.0±0.2 kg N/hm2 in 2009 and 2010, respectively. Moreover, linear equations describing monthly air temperature and precipitation showed a good fit to changes in soil NH3 emissions （r=0.506, P=0.014）. Overall, grazing intensities had less influence than that of climatic factors on soil NH3 emissions. Our findings provide new insights into the effects of grazing on NH3 volatili- zation from soil in Inner Mongolian grasslands, and have important implications for understanding N cycles in grassland ecosystems and for estimating soil NH3 emissions on a regional scale.展开更多
[Objective]The paper was to study the effect of different grazing intensities on vegetation characteristics of artificial pasture by plot rota-tion grazing experiment.[Method]Grazing intensity was divided into 2 treat...[Objective]The paper was to study the effect of different grazing intensities on vegetation characteristics of artificial pasture by plot rota-tion grazing experiment.[Method]Grazing intensity was divided into 2 treatments of heavy grazing and light grazing,and each treatment contained 6 plots,with randomized complete block design.A blank control was set near test plot.Ninety disease-free and healthy 2-year-old Yunling Black Goats with consistent body condition were selected and divided into 2 groups:heavy grazing(55)and light grazing(35).The goats were conduc-ted rotation grazing in 6 plots,and the average stocking rates were 12.6 and 8 goat/hm 2.The plant height,coverage,underground biomass and pasture plant nutrition of 2 treatments were measured,respectively.[Result]The cocksfoot height had significant difference with control under graz-ing conditions(P〈0.05),while the heights of ryegrass and white clover in control plot had no significant difference with that in grazing plot(P〉0.05).Grazing intensity had different effects on coverage of different plants;grazing utilization reduced the coverage of cocksfoot and ryegrass,which had little impact on coverage of white clover;viewed from the whole plant communities,the coverage in control plot was greater than that in grazing plot.The underground biomass in 0-20 cm soil depth in grazing plot accounted for about 90%;with the increase of grazing intensity,un-derground biomass was decreased.The crude protein(CP)and crude fat(EE)content of forage decreased,while acid detergent fiber(ADF)and neutral detergent fiber(NDF)increased.[Conclusion]The research provided scientific basis for determination of suitable grazing system and sus-tainable utilization of pasture resources.展开更多
Elucidating the distribution of the grazing pressure requires an understanding of the grazing activities.In this study,we analyzed the grazing behavior of yaks in Three-RiverSource Region(TRSR)and identified the main ...Elucidating the distribution of the grazing pressure requires an understanding of the grazing activities.In this study,we analyzed the grazing behavior of yaks in Three-RiverSource Region(TRSR)and identified the main factors influencing the distribution of grazing intensity(GI)using trajectory data and remote sensing datasets.Our results revealed that a semi-resident transhumance strategy is employed in this region.The average grazing time(GT)of four GPS collars over the year was 11.84 h/day(N6),11.01 h/day(N11),9.25 h/day(N18),and 11.61 h/day(N24).GT was generally higher in warm seasons(summer and autumn)than in cold seasons(spring and winter).The average daily moving speed was found to be closely related to the pasture size of different herders and the seasons.Geodetector analysis identified the distance to camp(DOC)as the most important single factor influencing the distribution of GI,explaining up to 52%of the GI variations.However,relying solely on this factor may not accurately depict the actual GI distribution.When pairwise factors interacted,the explanatory power of the model increased,ranging from 34.55%to 63.26%.Our study highlights the importance of considering multiple factors when predicting grazing intensity,as grazing activities tend to cluster near settlements,but other factors may also be influential.展开更多
The drag coefficient （Ca） and heat transfer coefficient （Ch） with the bulk transfer scheme are usually used to calculate the momentum and heat fluxes in meteorological models. The aerodynamic roughness length （z0...The drag coefficient （Ca） and heat transfer coefficient （Ch） with the bulk transfer scheme are usually used to calculate the momentum and heat fluxes in meteorological models. The aerodynamic roughness length （z0m） and thermal roughness length （z0h） are two crucial parameters for bulk transfer equations. To improve the meteorological models, the seasonal and interannual variations of Z0m, Z0h, coefficient kB-1, Cd, and Ch were investigated based on eddy covariance data over different grazed semiarid grasslands of Inner Mongolia during the growing seasons （May to September） from 2005 to 2008. For an ungrazed Leymus chinensis grassland （ungrazed since 1979）, Z0m and z0h had significant seasonal and in- terannual variations. Zorn was affected by the amount and distribution of rainfall, kB 1 exhibited a relatively negative variation compared with z0h, which indicates that the seasonal variation of z0h cannot be described by kB 1. To parameterize Zorn and z0h, the linear regressions between ln（z0m）, ln（z0h）, and the leaf area index （LAI） were performed with R2=0.71 and 0.83. The monthly average kB-1 was found to decrease linearly with LAI. The four-year averaged values of Ca and Ch were 4.5 × 10^-3 and 3.9× 10^-3, respectively. The monthly average Cd only varied by 8% while the variation of Ch was 18%, which reflects the dif- ferent impacts of dead vegetation on momentum and heat transfer at this natural grassland. Moreover, with the removal of vegetation cover, grazing intensities reduced Z0m, Z0h, Cd, and Ch.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
To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Hor...To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Horqin Sand Land, Inner Mongolia. The results showed that (1) the grazing was primary responsible for changes of the vegetation richness and diversity in the grazing grassland and that changing climate was the main reason for changes in the species richness and diversity in the grassland protected from grazing; (2) light and moderate grazing can promote restoration of the richness and the diversity in the degraded grassland, and heavy grazing could result in a decrease of the richness and diversity; (3) heavy grazing can result in significant decrease of the perennial diversity, and moderate and light grazing promotes increase of the perennial diversity; the grazing, whether heavy or moderate and light grazing, was beneficial to increase of the annual diversity; (4) heavy grazing was not beneficial to diversity of Graminean and Chenopodiaceae, and moderate and light grazing was favorable the diversity of Compositae and Chenopodiaceae; (5) the warm-humid climate was favorable to increase of the richness and the diversity, and the warm-drought climate could result in decease of the richness and the diversity; (6) increased precipitation was favorable to perennial diversity and the diversity of Graminean, Leguminosae, and Compositae, and decreased precipitation had few effects on the annual diversity and Chenopodiaceae diversity.展开更多
In order to understand the temporal changes of botanical composition in grassland ecosystem, and to clarify the relation between these changes and environmental impacts, such as climatic factors and artificial disturb...In order to understand the temporal changes of botanical composition in grassland ecosystem, and to clarify the relation between these changes and environmental impacts, such as climatic factors and artificial disturbance, a grazing trail was carried out during a 21-year period from 1974 at a sown grassland of the National Grassland Research Institute, located in Nishinasuno, the central area of Japan. The data sets of biomass for each mouth(from April to November)of the 21 year period were analyzed in this paper. The botanical composition of aboveground biomass varied greatly with both season and year. The biomass ratio of improved herbage species to invaded native plants gradually decreased each year. This may have been owing to meteorological factors, such as low air-temperature in winter, dry and hot summers, grassland management(including grazing intensity and fertilizer application), and inter-specific competition between native and introduced herbage plants.展开更多
Adipose tissue is a key factor in regulating meat quality.In this study,lipidomics was used to investigate differentially expressed lipids(DELs)associated with fat deposition and flavour in subcutaneous adipose tissue...Adipose tissue is a key factor in regulating meat quality.In this study,lipidomics was used to investigate differentially expressed lipids(DELs)associated with fat deposition and flavour in subcutaneous adipose tissue(SAT)of lambs under different grazing intensities(moderate grazing(MG)and heavy grazing(HG))with different supplementary feeding levels(No supplementary(NS),low supplementary(LS)and high supplementary(HS)).The results revealed that carcass quality and economic bennefits under moderate grazing or supplementary feeding conditions were superior to those under heavy grazing or non-supplementation regimes.Compared with MG-NS,HG-NS maintained SAT deposition through increased cardiolipin(CL)levels,but compromised lipid quality through accumulation of sphingolipids(e.g.,sphingomyelin),posing potential health concerns.Under HG conditions,supplementation unexpectedly reduced flavor precursor phospholipids such as phosphatidylglycerol.In contrast,moderate grazing provided a healthier source of lamb meat,with supplementary feeding further improving SAT deposition and flavor precursors through coordinated increases in CL and phosphatidylserine,elevated unsaturated fatty acids.These findings demonstrate that moderate grazing combined with strategic supplementation synergistically enhances meat quality and economic benefits,while revealing critical linkages between grassland utilization practices,lipidome-driven meat attributes and human dietary health.展开更多
＂Ryegrass, orchard grass, Festuca arundinacea and Trifolium repens＂ were researched in Dushan County, Guizhou Province, in order explore grass characteristics by different grazing methods in seasons. The results sho...＂Ryegrass, orchard grass, Festuca arundinacea and Trifolium repens＂ were researched in Dushan County, Guizhou Province, in order explore grass characteristics by different grazing methods in seasons. The results show that grass community height in different groups was of little differences（P0.05）; the group of moderate grazing in spring, summer and autumn dominated in grass cover; grass density showed insignificant variations among different treatment groups（P0.05） and in the groups of heavy grazing in spring and autumn and moderate grazing in summer and of moderate grazing in spring, summer and autumn, grass community density was higher compared with the other groups（P0.05）; as for above-ground biomass, the group of moderate grazing in spring and autumn and heavy grazing in summer and of moderate grazing in spring, summer and autumn dominated.展开更多
On an agrosilvopastoral farm in central Italy where Maremmana cattle graze in Turkey oak forests,we evaluated the impact of different livestock densities on stand structure,tree diversity and natural regeneration in f...On an agrosilvopastoral farm in central Italy where Maremmana cattle graze in Turkey oak forests,we evaluated the impact of different livestock densities on stand structure,tree diversity and natural regeneration in four types of grazed areas based on the grazing regime adopted:calf-grazed,high-intensity-grazed,low-intensity-grazed,ungrazed control.For each area,we set up three permanent circular plots(radius of 15 m)to survey the structural and dasometric characteristics of the overstorey,understorey,and regeneration layer.The results showed that grazing negatively affected the complexity of the forest structure and its potential to regenerate and maintain a high level of biodiversity.The differences in stand structure observed between the grazing areas were closely related to livestock density.The most sensitive components of the system were the understorey and the regeneration layers.Contrarily,the current grazing management did not affect the dominant tree structure or its composition.Our findings identified medium-term monitoring and regeneration management as the two significant aspects to consider when assessing sustainable livestock.New forests can be established by excluding graz-ing for about 20–25 years.展开更多
The continuous increase of livestock production in Inner Mongolia has caused severe degradation of the grassland ecosystems in recent years. Previous grazing experiments have shown a wide range of vegetation responses...The continuous increase of livestock production in Inner Mongolia has caused severe degradation of the grassland ecosystems in recent years. Previous grazing experiments have shown a wide range of vegetation responses between the biome types on a global scale, but there is still a lack of sufficient studies to discern the relative responses of a given biome type. We conducted a meta-analysis of vegetation coverage(VC), plant density(PD), total biomass(TB), above-ground biomass(AGB), under-ground biomass(UGB) and Shannon–Weaver Index(SI) in different grassland types in Inner Mongolia obtained under conditions of different grazing intensities and durations. The results showed that grazing decreased VC, TB, AGB, UGB, and PD significantly. Compared to the global and national average values, the negative effects of grazing to steppe biomass in Inner Mongolia were higher than that on the global scale, while less pronounced than that in China. TB of the meadow steppe in Inner Mongolia increased by 40% under moderate grazing intensity and duration because of compensatory growth. SI of the desert and meadow steppe showed negative linear relationships with the grazing intensity in Inner Mongolia. The percentage changes in AGB, PD, and SI to grazing showed quadratic relationships with the mean annual temperature of the experimental year. With increasing mean annual precipitation, the negative effects of grazing on UGB and SI first decreased and then increased, with that of VC and grazing showing a cubic relationship.展开更多
Background The savannah ecosystems of Sahel have experienced continuous and heavy grazing of livestock for centuries but still,their vegetation response to grazing pressure remains poorly understood.In this study,we a...Background The savannah ecosystems of Sahel have experienced continuous and heavy grazing of livestock for centuries but still,their vegetation response to grazing pressure remains poorly understood.In this study,we analysed the herbaceous plant dynamics,measured by species diversity,composition,cover,and biomass in response to grazing pressure in the savannah ecosystems of Sahel.In Senegal,we selected four savannah sites represented with high,moderate,light and no grazing intensity levels.Transect survey methods were used for sampling the vegetation data within each of the sites.Species richness and composition were analysed using species accumulation curve and multivariate analyses.Furthermore,we used General Linear Models and a piecewise Structural Equation Model(pSEM)to examine the relationships between grazing intensity,vegetation cover,diversity and biomass.Results The herbaceous species diversity and composition varied significantly among the different grazing intensity levels(p<0.001).The plant species composition shifted from the dominance of grass cover to the dominance of forb cover with increasing grazing pressure.Moreover,the attributes of species diversity,herbaceous biomass,and ground cover were higher on sites with low grazing than sites with high and moderate grazing intensity.Across all sites,species diversity was positively related to total biomass.The pSEM explained 37%of the variance in total biomass and revealed that grazing intensity negatively influenced total biomass both directly and indirectly through its negative influence on species diversity.Conclusions Managing grazing intensity may lead to higher plant production and higher mixed forage establishment in the dryland savannah ecosystems.This information can be used to support land management strategies and promote sustainable grazing practices that balance the needs of livestock with the conservation of ecosystem health and biodiversity.展开更多
Background Livestock production is an economically significant activity in grassland-based production systems with herbivory,a critical process in modifying plant structure and regulating biomass dynamics in these are...Background Livestock production is an economically significant activity in grassland-based production systems with herbivory,a critical process in modifying plant structure and regulating biomass dynamics in these areas.Methods A grazing simulation experiment was undertaken in a semi-arid environment in Kenya to determine the effects of clipping frequency and intensity on the morphology and productivity of Cenchrus ciliaris and Panicum maximum grass ecotypes.The ecotypes were clipped at different frequencies(every 2,4,and 12 weeks)and different intensities(5,10,and 15 cm clipping heights).The morphological responses of the grass ecotypes and biomass yields were determined.Results The grass ecotypes showed significantly(p<0.05)varied responses to cutting frequency and intensity.Morphological parameters,tillering,and biomass production were all affected by clipping frequency and intensity.The highest dry matter(DM)yields were recorded under low frequency(LF)clipping,followed by moderate frequency(MF)clipping and high frequency(HF)clipping.LF clipping in C.ciliaris ecotype Kilifi was 20%and 31%more compared to MF and HF clipping.No significant difference in yields was found by cutting the C.ciliaris ecotype Magadi at 4-and 12-week intervals,even though clipping at 2-week intervals cumulatively yielded less biomass.There was a biomass yield reduction in P.maximum ecotype Taveta of 23%and 25%for MF and HF clipping,respectively,while for ecotype Isinya,the reduction was 13%and 15%for MF and HF,respectively.Clipping intensity had a significant(p<0.05)effect on cumulative yields in C.ciliaris ecotypes,but not P.maximum.Ecotypic differences were apparent in both C.ciliaris and P.maximum ecotype DM yields.Conclusions The results in this study suggest that clipping range grass ecotypes less frequently(4-and 12-week intervals)and at 10 and 15 cm stubble heights results in higher biomass yields.Generally,LF and MF grazing and cutting strategies are advantageous for semi-arid lands.Combinations of frequent and high-intensity utilization grazing strategies should be discouraged as they are likely to lead to reduced biomass yields and negative effects both on grasses and on the environment.展开更多
Background:Feed is the most costly input for US ruminant livestock production systems,and increasing the utilization efficiency of irrigated forage systems can improve system profitability.This study assessed the prod...Background:Feed is the most costly input for US ruminant livestock production systems,and increasing the utilization efficiency of irrigated forage systems can improve system profitability.This study assessed the production,utilization,and quality of 22 intensively managed perennial grasses and legumes.Methods:Forages were cultivated as monocultures under irrigation and subjected to mob stocking or similarly frequent and intense mowing for 2 years at 6‐week intervals between May and September.Twenty‐two grasses and legumes were randomly assigned to adjacent 1.5‐m‐wide×9‐m‐long split subplots within each whole plot of eight replications,and the eight replications were grouped into four pairs,with the two replications per pair randomly assigned to defoliation either by grazing or mowing.Results:Seven mostly warm‐season grasses did not persist following the first defoliation,and accumulation for three legume species could be evaluated only twice in Year 1.For the 12 remaining forage species defoliated four times in both years,defoliation management did not affect dry matter accumulation or removal,but utilization was 10%greater under grazing than mowing(p=0.0031).Conclusions:Under 6‐week‐long rest periods,numerous irrigated cool‐season grasses and temperate legumes were tolerant of repeated mob grazing.展开更多
Aims Grasslands are the world’s most extensive terrestrial ecosystem,and are a major feed source for livestock.Meeting increasing demand for meat and other dairy products in a sustainable manner is a big challenge.At...Aims Grasslands are the world’s most extensive terrestrial ecosystem,and are a major feed source for livestock.Meeting increasing demand for meat and other dairy products in a sustainable manner is a big challenge.At a field scale,Global Positioning System and ground-based sensor technologies provide promising tools for grassland and herd management with high precision.With the growth in availability of spaceborne remote sensing data,it is therefore important to revisit the relevant methods and applications that can exploit this imagery.In this article,we have reviewed the(i)current status of grassland monitoring/observation methods and applications based on satellite remote sensing data,(ii)the technological and methodological developments to retrieve different grassland biophysical parameters and management characteristics(i.e.degradation,grazing intensity)and(iii)identified the key remaining challenges and some new upcoming trends for future development.Important Findings The retrieval of grassland biophysical parameters have evolved in recent years from classical regression analysis to more complex,efficient and robust modeling approaches,driven by satellite data,and are likely to continue to be the most robust method for deriving grassland information,however these require more high quality calibration and validation data.We found that the hypertemporal satellite data are widely used for time series generation,and particularly to overcome cloud contamination issues,but the current low spatial resolution of these instruments precludes their use for field-scale application in many countries.This trend may change with the current rise in launch of satellite constellations,such as RapidEye,Sentinel-2 and even the microsatellites such as those operated by Skybox Imaging.Microwave imagery has not been widely used for grassland applications,and a better understanding of the backscatter behaviour from different phenological stages is needed for more reliable products in cloudy regions.The development of hyperspectral satellite instrumentation and analytical methods will help for more detailed discrimination of habitat types,and the development of tools for greater end-user operation.展开更多
Aims Natural 15N abundance provides integrated information about nitrogen(N)input,transformation and output,indirectly reflecting N cycling traits within terrestrial ecosystems.However,relationships between natural 15...Aims Natural 15N abundance provides integrated information about nitrogen(N)input,transformation and output,indirectly reflecting N cycling traits within terrestrial ecosystems.However,relationships between natural 15N abundance and N cycling processes are poorly understood in China.Here,our primary objectives were to(i)examine the effects of grazing at varying levels of intensity on d15N of soils and plants in a semi-arid grassland;(ii)detect the relationships between d15N of soils and four major N cycling processes(i.e.mineralization,nitrification,denitrification and ammonia volatilization);and(iii)determine whether d15N of soils can be used as an indicator of N cycling in this semi-arid grassland.Methods The field experiment was conducted within the long-term(17-year)grazing enclosures in a semi-arid grassland in Inner Mongolia.Five grazing intensities(0.00,1.33,2.67,4.00 and 5.33 sheep ha1)were designed.d15N values of topsoils(0–10 cm),surface soils(0–2 cm)and plants were measured in 2006.Differences in d15N of soils and plants between the five grazing intensities were examined.Rates of four soil N cycling processes were measured periodically during the 2005 and 2006 growing seasons.The d15N values of topsoils were linked to the four N cycling processes to investigate their relationships.Important Findings The d15N values of topsoils(5.20–5.96&)were substantially higher than the d15N values of plants(2.51–2.93&)and surface soils(1.44–2.92&)regardless of grazing intensities.The 15N-depleted N losses during microbial decomposition of organic matter in concert with the downward movement of residual substrate over time are the possible causes of higher d15N values in topsoils than in surface soils.In addition,the d15N values of topsoils were positively correlated with the d15N values of both plants and surface soils.Grazing,especially the high-intensity grazing(5.33 sheep ha1),resulted in a significant decrease in d15N of surface soils.However,no statistically significant variations in d15N of topsoils and plants were found in response to grazing.The d15N values of topsoils exhibited significant dependence on the cumulative rates of NH3 volatilization,net nitrification and denitrification in 2005 but not in 2006.展开更多
In 1997, we conducted a vegetation survey in three semi-arid natural grasslands （steppes） with different livestock grazing intensities in Southwest Heilongjiang Province, China, The dominant grassland species was th...In 1997, we conducted a vegetation survey in three semi-arid natural grasslands （steppes） with different livestock grazing intensities in Southwest Heilongjiang Province, China, The dominant grassland species was the grass Stipa baicalensis Roshev. Grasslands with light, intermediate, and heavy grazing intensities were located 10, 5, and 2 km from a village, respectively. Villagers use the steppe to raise cattle, horses, sheep, and goats. Each of the three grasslands was surveyed by placing 100 quadrats （50 cm×50 cm） along a 50 m line transect. Each quadrat was divided into four equal areas （25 cm×25 cm; S-quadrats） and all plant species occurring in each of these smaller areas were identified and recorded. These data were summarized into frequency distributions and the percentage of S-quadrats containing a given species and the variance of each species were estimated. The power law was applied to these estimates. The power law was used to evaluate the spatial heterogeneity and frequency of occurrence for each species in the grassland community. The lightly grazed grassland exhibited high spatial heterogeneity （caused by large plant size）, the highest species diversity, and a high occurrence of S. baicalensis. In contrast, the heavily grazed grassland exhibited high spatial heterogeneity （caused by patchy populations of small plant size）, low species diversity, and a low occurrence of S. baicalensis. We judged that the heavily grazed grassland was overgrazed and exclusion of livestock from the degraded areas is necessary for recovery.展开更多
基金supported by the General Program of the National Natural Science Foundation of China(32271716)the National Key Research and Development Program(2021YFD1300504)+1 种基金the Key Projects of the Natural Science of Foundation of Gansu Province(23JRRA1023)the Starting Research Fund for the Introduction of Talent of Lanzhou University(561120205).
文摘While substantial nitrogen(N)input from yak urine in intensively grazed grasslands on the Qinghai-Tibetan Plateau(QTP)is well documented,the species-specific responses of dominant forage plants-particularly regarding N uptake efficiency,environmental impacts,and associated microbial dynamics-remain poorly understood.This study investigated Elymus nutans(Gramineae)and Kobresia graminifolia(Cyperaceae),two ecologically dominant species,to elucidate the divergent nitrogen transformation features under urine deposition.During the growing season,we simulated yak urine input by applying 640 mL urine per 40 cm×40 cm patch in natural grasslands.Over six weeks,we measured total plant N uptake and soil nitrous oxide(N_(2)O)emissions and evaluated soil nitrification rates through a 2-week indoor incubation experiment.To elucidate the underlying microbial mechanisms,we analysed the abundance and composition of rhizosphere ammonia-oxidizing archaea(AOA)and bacteria(AOB).Results showed that K.graminifolia exhibited significantly lower soil nitrification rates and N_(2)O emissions but higher total N uptake compared to E.nutans.Furthermore,K.graminifolia soil had lower AOB and higher AOA abundances.Specifically,the relative abundances of Nitrosophaera and Candidatus Nitrosocosmicus within AOA,as well as Nitrosovibrio and Nitrosomonas within AOB,were higher in K.graminifolia soil.These findings indicate that variations in nitrifier populations may be key drivers of differences in N uptake and N_(2)O emissions across dominant forage species.This study provides valuable insights for developing effective management strategies for intensively grazed grasslands on the QTP.
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National Natural Science Foundation of China,No.41671080
文摘Changes in soil organic carbon(SOC) in rangelands has been extensively investigated. Grazing in outlying rangeland areas has caused severe impacts on ecosystem functions. To reveal the effects of grazing on SOC, we evaluated the grassland in Xilin Gol League, Inner Mongolia, China. Grazing intensity was determined by using two image sets of vegetation index with normalized differences in grazing periods(July 12 th and 28th). The range of variation in vegetation index was then used to measure the grazing intensity. The SOC storage and density were obtained by conducting experiments on field soil samples. Results showed that 1) the grazing intensity in Xilin Gol League declined gradually from west to east; by contrast, the spatial distribution of SOC density increased gradually. 2) As grazing intensity increased, the carbon storage of rangeland decreased evidently. Minimum carbon storage was observed in grasslands classified under extreme overgrazing; by comparison, maximum values were found in areas classified under light overgrazing to moderate grazing. 3) The estimated soil carbon storage was 8.48 × 10^(11) kg, and the average carbon density was 4.08 kg/m^2. Our research demonstrated that grazing intensity likely affects soil carbon. Moderate grazing is an optimum strategy to maintain carbon storage and ensure sustainable grassland utilization.
基金Funding for this work came from the National Natural Science Foundation of China (30830026)the National Basic Research Program of China (2009CB825103)the Innovative Research Group Project of the National Natural Science Foundation of China (30821062)
文摘Ammonia （NH3） emission and redeposition play a major role in terrestrial nitrogen （N） cycles and can also cause environmental problems, such as changes in biodiversity, soil acidity, and eutrophication. Previous field grazing experiments showed inconsistent （positive, neutral, and negative） NH3 volatilization from soils in response to varying grazing intensities. However, it remains unclear whether, or to what extent, NH3 emissions from soil are affected by increasing grazing intensities in Inner Mongolian grasslands. Using a 5-year grazing experiment, we investigated the relationship between NH3 volatilization from soil and grazing pressure （0.0, 3.0, 6.0, and 9.0 sheep/hm2） from June to September of 2009 and 2010 via the vented-chamber method. The results show that soil NH3 volatilization was not significantly different at different grazing intensities in 2009, although it was higher at the highest stocking rate during 2010. There was no significant linear relationship between soil NH3 volatilization rates and soil NH4^-N, but soil NH3 volatilization rates were significantly related to soil water content and air temperature. Grazing intensities had no significant influence on soil NH3 volatilization. Soil NH3 emissions from June to Sep- tember （grazing period）, averaged over all grazing intensities, were 9.6±0.2 and 19.0±0.2 kg N/hm2 in 2009 and 2010, respectively. Moreover, linear equations describing monthly air temperature and precipitation showed a good fit to changes in soil NH3 emissions （r=0.506, P=0.014）. Overall, grazing intensities had less influence than that of climatic factors on soil NH3 emissions. Our findings provide new insights into the effects of grazing on NH3 volatili- zation from soil in Inner Mongolian grasslands, and have important implications for understanding N cycles in grassland ecosystems and for estimating soil NH3 emissions on a regional scale.
基金funded by Scientific Research Project of Public Service Industry"Bearing Capacity and Livestock Configuration of Pasture in Different Regions(200903060)
文摘[Objective]The paper was to study the effect of different grazing intensities on vegetation characteristics of artificial pasture by plot rota-tion grazing experiment.[Method]Grazing intensity was divided into 2 treatments of heavy grazing and light grazing,and each treatment contained 6 plots,with randomized complete block design.A blank control was set near test plot.Ninety disease-free and healthy 2-year-old Yunling Black Goats with consistent body condition were selected and divided into 2 groups:heavy grazing(55)and light grazing(35).The goats were conduc-ted rotation grazing in 6 plots,and the average stocking rates were 12.6 and 8 goat/hm 2.The plant height,coverage,underground biomass and pasture plant nutrition of 2 treatments were measured,respectively.[Result]The cocksfoot height had significant difference with control under graz-ing conditions(P〈0.05),while the heights of ryegrass and white clover in control plot had no significant difference with that in grazing plot(P〉0.05).Grazing intensity had different effects on coverage of different plants;grazing utilization reduced the coverage of cocksfoot and ryegrass,which had little impact on coverage of white clover;viewed from the whole plant communities,the coverage in control plot was greater than that in grazing plot.The underground biomass in 0-20 cm soil depth in grazing plot accounted for about 90%;with the increase of grazing intensity,un-derground biomass was decreased.The crude protein(CP)and crude fat(EE)content of forage decreased,while acid detergent fiber(ADF)and neutral detergent fiber(NDF)increased.[Conclusion]The research provided scientific basis for determination of suitable grazing system and sus-tainable utilization of pasture resources.
基金The Second Tibetan Plateau Scientific Expedition and Research,No.2019QZKK0603Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA20040201National Natural Science Foundation of China,No.41671104。
文摘Elucidating the distribution of the grazing pressure requires an understanding of the grazing activities.In this study,we analyzed the grazing behavior of yaks in Three-RiverSource Region(TRSR)and identified the main factors influencing the distribution of grazing intensity(GI)using trajectory data and remote sensing datasets.Our results revealed that a semi-resident transhumance strategy is employed in this region.The average grazing time(GT)of four GPS collars over the year was 11.84 h/day(N6),11.01 h/day(N11),9.25 h/day(N18),and 11.61 h/day(N24).GT was generally higher in warm seasons(summer and autumn)than in cold seasons(spring and winter).The average daily moving speed was found to be closely related to the pasture size of different herders and the seasons.Geodetector analysis identified the distance to camp(DOC)as the most important single factor influencing the distribution of GI,explaining up to 52%of the GI variations.However,relying solely on this factor may not accurately depict the actual GI distribution.When pairwise factors interacted,the explanatory power of the model increased,ranging from 34.55%to 63.26%.Our study highlights the importance of considering multiple factors when predicting grazing intensity,as grazing activities tend to cluster near settlements,but other factors may also be influential.
基金supported by the German Science Foundation (DFG) within the Research Group 536"MAGIM" (Matter fluxes in grasslands of Inner Mongolia as influenced by stocking rate) under Grant BE 172/7-1 in cooperation with Inner Mongolia Grassland Ecosystem Research Stationthe National Basic Research Program of China (973 Program) under Grant 2010CB951801the Strategic Priority Research Program of Chinese Academy of Sciences under Grant XDA05110102
文摘The drag coefficient （Ca） and heat transfer coefficient （Ch） with the bulk transfer scheme are usually used to calculate the momentum and heat fluxes in meteorological models. The aerodynamic roughness length （z0m） and thermal roughness length （z0h） are two crucial parameters for bulk transfer equations. To improve the meteorological models, the seasonal and interannual variations of Z0m, Z0h, coefficient kB-1, Cd, and Ch were investigated based on eddy covariance data over different grazed semiarid grasslands of Inner Mongolia during the growing seasons （May to September） from 2005 to 2008. For an ungrazed Leymus chinensis grassland （ungrazed since 1979）, Z0m and z0h had significant seasonal and in- terannual variations. Zorn was affected by the amount and distribution of rainfall, kB 1 exhibited a relatively negative variation compared with z0h, which indicates that the seasonal variation of z0h cannot be described by kB 1. To parameterize Zorn and z0h, the linear regressions between ln（z0m）, ln（z0h）, and the leaf area index （LAI） were performed with R2=0.71 and 0.83. The monthly average kB-1 was found to decrease linearly with LAI. The four-year averaged values of Ca and Ch were 4.5 × 10^-3 and 3.9× 10^-3, respectively. The monthly average Cd only varied by 8% while the variation of Ch was 18%, which reflects the dif- ferent impacts of dead vegetation on momentum and heat transfer at this natural grassland. Moreover, with the removal of vegetation cover, grazing intensities reduced Z0m, Z0h, Cd, and Ch.
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.
基金funded by one of the 973 Projects (2009CB421303)
文摘To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Horqin Sand Land, Inner Mongolia. The results showed that (1) the grazing was primary responsible for changes of the vegetation richness and diversity in the grazing grassland and that changing climate was the main reason for changes in the species richness and diversity in the grassland protected from grazing; (2) light and moderate grazing can promote restoration of the richness and the diversity in the degraded grassland, and heavy grazing could result in a decrease of the richness and diversity; (3) heavy grazing can result in significant decrease of the perennial diversity, and moderate and light grazing promotes increase of the perennial diversity; the grazing, whether heavy or moderate and light grazing, was beneficial to increase of the annual diversity; (4) heavy grazing was not beneficial to diversity of Graminean and Chenopodiaceae, and moderate and light grazing was favorable the diversity of Compositae and Chenopodiaceae; (5) the warm-humid climate was favorable to increase of the richness and the diversity, and the warm-drought climate could result in decease of the richness and the diversity; (6) increased precipitation was favorable to perennial diversity and the diversity of Graminean, Leguminosae, and Compositae, and decreased precipitation had few effects on the annual diversity and Chenopodiaceae diversity.
文摘In order to understand the temporal changes of botanical composition in grassland ecosystem, and to clarify the relation between these changes and environmental impacts, such as climatic factors and artificial disturbance, a grazing trail was carried out during a 21-year period from 1974 at a sown grassland of the National Grassland Research Institute, located in Nishinasuno, the central area of Japan. The data sets of biomass for each mouth(from April to November)of the 21 year period were analyzed in this paper. The botanical composition of aboveground biomass varied greatly with both season and year. The biomass ratio of improved herbage species to invaded native plants gradually decreased each year. This may have been owing to meteorological factors, such as low air-temperature in winter, dry and hot summers, grassland management(including grazing intensity and fertilizer application), and inter-specific competition between native and introduced herbage plants.
基金supported by the National Natural Science Foundation of China(32192463)the China Agriculture Research System(CARS-38).
文摘Adipose tissue is a key factor in regulating meat quality.In this study,lipidomics was used to investigate differentially expressed lipids(DELs)associated with fat deposition and flavour in subcutaneous adipose tissue(SAT)of lambs under different grazing intensities(moderate grazing(MG)and heavy grazing(HG))with different supplementary feeding levels(No supplementary(NS),low supplementary(LS)and high supplementary(HS)).The results revealed that carcass quality and economic bennefits under moderate grazing or supplementary feeding conditions were superior to those under heavy grazing or non-supplementation regimes.Compared with MG-NS,HG-NS maintained SAT deposition through increased cardiolipin(CL)levels,but compromised lipid quality through accumulation of sphingolipids(e.g.,sphingomyelin),posing potential health concerns.Under HG conditions,supplementation unexpectedly reduced flavor precursor phospholipids such as phosphatidylglycerol.In contrast,moderate grazing provided a healthier source of lamb meat,with supplementary feeding further improving SAT deposition and flavor precursors through coordinated increases in CL and phosphatidylserine,elevated unsaturated fatty acids.These findings demonstrate that moderate grazing combined with strategic supplementation synergistically enhances meat quality and economic benefits,while revealing critical linkages between grassland utilization practices,lipidome-driven meat attributes and human dietary health.
基金Supported by Guizhou Academy of Agricultural Sciences Foundation(2010023)Guizhou Academy of Agricultural Sciences Special Funds([2011]021)Guizhou Academy of Agricultural Sciences Foundation for the Talents([2011]01)~~
文摘＂Ryegrass, orchard grass, Festuca arundinacea and Trifolium repens＂ were researched in Dushan County, Guizhou Province, in order explore grass characteristics by different grazing methods in seasons. The results show that grass community height in different groups was of little differences（P0.05）; the group of moderate grazing in spring, summer and autumn dominated in grass cover; grass density showed insignificant variations among different treatment groups（P0.05） and in the groups of heavy grazing in spring and autumn and moderate grazing in summer and of moderate grazing in spring, summer and autumn, grass community density was higher compared with the other groups（P0.05）; as for above-ground biomass, the group of moderate grazing in spring and autumn and heavy grazing in summer and of moderate grazing in spring, summer and autumn dominated.
基金This research is related to the project GO NEWTON“Agroforestry Network in Tuscany”,financed by the Tuscany Region through the Measure 16.2 of Rural Development Plan 2014-2020 to promote agroforestry systems by spreading knowledge to farmers and promoting innovation in the Tuscan territory.
文摘On an agrosilvopastoral farm in central Italy where Maremmana cattle graze in Turkey oak forests,we evaluated the impact of different livestock densities on stand structure,tree diversity and natural regeneration in four types of grazed areas based on the grazing regime adopted:calf-grazed,high-intensity-grazed,low-intensity-grazed,ungrazed control.For each area,we set up three permanent circular plots(radius of 15 m)to survey the structural and dasometric characteristics of the overstorey,understorey,and regeneration layer.The results showed that grazing negatively affected the complexity of the forest structure and its potential to regenerate and maintain a high level of biodiversity.The differences in stand structure observed between the grazing areas were closely related to livestock density.The most sensitive components of the system were the understorey and the regeneration layers.Contrarily,the current grazing management did not affect the dominant tree structure or its composition.Our findings identified medium-term monitoring and regeneration management as the two significant aspects to consider when assessing sustainable livestock.New forests can be established by excluding graz-ing for about 20–25 years.
基金The National Key Research and Development Program of China (2017YFA0604803)。
文摘The continuous increase of livestock production in Inner Mongolia has caused severe degradation of the grassland ecosystems in recent years. Previous grazing experiments have shown a wide range of vegetation responses between the biome types on a global scale, but there is still a lack of sufficient studies to discern the relative responses of a given biome type. We conducted a meta-analysis of vegetation coverage(VC), plant density(PD), total biomass(TB), above-ground biomass(AGB), under-ground biomass(UGB) and Shannon–Weaver Index(SI) in different grassland types in Inner Mongolia obtained under conditions of different grazing intensities and durations. The results showed that grazing decreased VC, TB, AGB, UGB, and PD significantly. Compared to the global and national average values, the negative effects of grazing to steppe biomass in Inner Mongolia were higher than that on the global scale, while less pronounced than that in China. TB of the meadow steppe in Inner Mongolia increased by 40% under moderate grazing intensity and duration because of compensatory growth. SI of the desert and meadow steppe showed negative linear relationships with the grazing intensity in Inner Mongolia. The percentage changes in AGB, PD, and SI to grazing showed quadratic relationships with the mean annual temperature of the experimental year. With increasing mean annual precipitation, the negative effects of grazing on UGB and SI first decreased and then increased, with that of VC and grazing showing a cubic relationship.
基金funded by the New Zealand Government to support the objectives of the Global Research Alliance on Agricultural Greenhouse Gasesthe CaSSECS project(Carbon Sequestration and Green-house Gas Emissions in(Agro)Sylvopastoral Ecosystems in the Sahelian CILSS States)[FOOD/2019/410-169]+1 种基金Tagesson was additionally funded by the Swedish National Space Agency(SNSA 2021-001442021-00111)and FORMAS(Dnr.2021-00644).
文摘Background The savannah ecosystems of Sahel have experienced continuous and heavy grazing of livestock for centuries but still,their vegetation response to grazing pressure remains poorly understood.In this study,we analysed the herbaceous plant dynamics,measured by species diversity,composition,cover,and biomass in response to grazing pressure in the savannah ecosystems of Sahel.In Senegal,we selected four savannah sites represented with high,moderate,light and no grazing intensity levels.Transect survey methods were used for sampling the vegetation data within each of the sites.Species richness and composition were analysed using species accumulation curve and multivariate analyses.Furthermore,we used General Linear Models and a piecewise Structural Equation Model(pSEM)to examine the relationships between grazing intensity,vegetation cover,diversity and biomass.Results The herbaceous species diversity and composition varied significantly among the different grazing intensity levels(p<0.001).The plant species composition shifted from the dominance of grass cover to the dominance of forb cover with increasing grazing pressure.Moreover,the attributes of species diversity,herbaceous biomass,and ground cover were higher on sites with low grazing than sites with high and moderate grazing intensity.Across all sites,species diversity was positively related to total biomass.The pSEM explained 37%of the variance in total biomass and revealed that grazing intensity negatively influenced total biomass both directly and indirectly through its negative influence on species diversity.Conclusions Managing grazing intensity may lead to higher plant production and higher mixed forage establishment in the dryland savannah ecosystems.This information can be used to support land management strategies and promote sustainable grazing practices that balance the needs of livestock with the conservation of ecosystem health and biodiversity.
文摘Background Livestock production is an economically significant activity in grassland-based production systems with herbivory,a critical process in modifying plant structure and regulating biomass dynamics in these areas.Methods A grazing simulation experiment was undertaken in a semi-arid environment in Kenya to determine the effects of clipping frequency and intensity on the morphology and productivity of Cenchrus ciliaris and Panicum maximum grass ecotypes.The ecotypes were clipped at different frequencies(every 2,4,and 12 weeks)and different intensities(5,10,and 15 cm clipping heights).The morphological responses of the grass ecotypes and biomass yields were determined.Results The grass ecotypes showed significantly(p<0.05)varied responses to cutting frequency and intensity.Morphological parameters,tillering,and biomass production were all affected by clipping frequency and intensity.The highest dry matter(DM)yields were recorded under low frequency(LF)clipping,followed by moderate frequency(MF)clipping and high frequency(HF)clipping.LF clipping in C.ciliaris ecotype Kilifi was 20%and 31%more compared to MF and HF clipping.No significant difference in yields was found by cutting the C.ciliaris ecotype Magadi at 4-and 12-week intervals,even though clipping at 2-week intervals cumulatively yielded less biomass.There was a biomass yield reduction in P.maximum ecotype Taveta of 23%and 25%for MF and HF clipping,respectively,while for ecotype Isinya,the reduction was 13%and 15%for MF and HF,respectively.Clipping intensity had a significant(p<0.05)effect on cumulative yields in C.ciliaris ecotypes,but not P.maximum.Ecotypic differences were apparent in both C.ciliaris and P.maximum ecotype DM yields.Conclusions The results in this study suggest that clipping range grass ecotypes less frequently(4-and 12-week intervals)and at 10 and 15 cm stubble heights results in higher biomass yields.Generally,LF and MF grazing and cutting strategies are advantageous for semi-arid lands.Combinations of frequent and high-intensity utilization grazing strategies should be discouraged as they are likely to lead to reduced biomass yields and negative effects both on grasses and on the environment.
基金supported by the Utah Agricultural Experiment Station,Utah State University,and approved as journal paper number 9783approved by the Utah State University Institutional Animal Care and Use Committee as Protocol 1130.
文摘Background:Feed is the most costly input for US ruminant livestock production systems,and increasing the utilization efficiency of irrigated forage systems can improve system profitability.This study assessed the production,utilization,and quality of 22 intensively managed perennial grasses and legumes.Methods:Forages were cultivated as monocultures under irrigation and subjected to mob stocking or similarly frequent and intense mowing for 2 years at 6‐week intervals between May and September.Twenty‐two grasses and legumes were randomly assigned to adjacent 1.5‐m‐wide×9‐m‐long split subplots within each whole plot of eight replications,and the eight replications were grouped into four pairs,with the two replications per pair randomly assigned to defoliation either by grazing or mowing.Results:Seven mostly warm‐season grasses did not persist following the first defoliation,and accumulation for three legume species could be evaluated only twice in Year 1.For the 12 remaining forage species defoliated four times in both years,defoliation management did not affect dry matter accumulation or removal,but utilization was 10%greater under grazing than mowing(p=0.0031).Conclusions:Under 6‐week‐long rest periods,numerous irrigated cool‐season grasses and temperate legumes were tolerant of repeated mob grazing.
基金Teagasc Walsh Fellowship Program for funding this research.
文摘Aims Grasslands are the world’s most extensive terrestrial ecosystem,and are a major feed source for livestock.Meeting increasing demand for meat and other dairy products in a sustainable manner is a big challenge.At a field scale,Global Positioning System and ground-based sensor technologies provide promising tools for grassland and herd management with high precision.With the growth in availability of spaceborne remote sensing data,it is therefore important to revisit the relevant methods and applications that can exploit this imagery.In this article,we have reviewed the(i)current status of grassland monitoring/observation methods and applications based on satellite remote sensing data,(ii)the technological and methodological developments to retrieve different grassland biophysical parameters and management characteristics(i.e.degradation,grazing intensity)and(iii)identified the key remaining challenges and some new upcoming trends for future development.Important Findings The retrieval of grassland biophysical parameters have evolved in recent years from classical regression analysis to more complex,efficient and robust modeling approaches,driven by satellite data,and are likely to continue to be the most robust method for deriving grassland information,however these require more high quality calibration and validation data.We found that the hypertemporal satellite data are widely used for time series generation,and particularly to overcome cloud contamination issues,but the current low spatial resolution of these instruments precludes their use for field-scale application in many countries.This trend may change with the current rise in launch of satellite constellations,such as RapidEye,Sentinel-2 and even the microsatellites such as those operated by Skybox Imaging.Microwave imagery has not been widely used for grassland applications,and a better understanding of the backscatter behaviour from different phenological stages is needed for more reliable products in cloudy regions.The development of hyperspectral satellite instrumentation and analytical methods will help for more detailed discrimination of habitat types,and the development of tools for greater end-user operation.
基金State Key Basic Research and Development Program of China(2010CB833502)Chinese Academy of Sciences(KZCX2-XB2-01).
文摘Aims Natural 15N abundance provides integrated information about nitrogen(N)input,transformation and output,indirectly reflecting N cycling traits within terrestrial ecosystems.However,relationships between natural 15N abundance and N cycling processes are poorly understood in China.Here,our primary objectives were to(i)examine the effects of grazing at varying levels of intensity on d15N of soils and plants in a semi-arid grassland;(ii)detect the relationships between d15N of soils and four major N cycling processes(i.e.mineralization,nitrification,denitrification and ammonia volatilization);and(iii)determine whether d15N of soils can be used as an indicator of N cycling in this semi-arid grassland.Methods The field experiment was conducted within the long-term(17-year)grazing enclosures in a semi-arid grassland in Inner Mongolia.Five grazing intensities(0.00,1.33,2.67,4.00 and 5.33 sheep ha1)were designed.d15N values of topsoils(0–10 cm),surface soils(0–2 cm)and plants were measured in 2006.Differences in d15N of soils and plants between the five grazing intensities were examined.Rates of four soil N cycling processes were measured periodically during the 2005 and 2006 growing seasons.The d15N values of topsoils were linked to the four N cycling processes to investigate their relationships.Important Findings The d15N values of topsoils(5.20–5.96&)were substantially higher than the d15N values of plants(2.51–2.93&)and surface soils(1.44–2.92&)regardless of grazing intensities.The 15N-depleted N losses during microbial decomposition of organic matter in concert with the downward movement of residual substrate over time are the possible causes of higher d15N values in topsoils than in surface soils.In addition,the d15N values of topsoils were positively correlated with the d15N values of both plants and surface soils.Grazing,especially the high-intensity grazing(5.33 sheep ha1),resulted in a significant decrease in d15N of surface soils.However,no statistically significant variations in d15N of topsoils and plants were found in response to grazing.The d15N values of topsoils exhibited significant dependence on the cumulative rates of NH3 volatilization,net nitrification and denitrification in 2005 but not in 2006.
文摘In 1997, we conducted a vegetation survey in three semi-arid natural grasslands （steppes） with different livestock grazing intensities in Southwest Heilongjiang Province, China, The dominant grassland species was the grass Stipa baicalensis Roshev. Grasslands with light, intermediate, and heavy grazing intensities were located 10, 5, and 2 km from a village, respectively. Villagers use the steppe to raise cattle, horses, sheep, and goats. Each of the three grasslands was surveyed by placing 100 quadrats （50 cm×50 cm） along a 50 m line transect. Each quadrat was divided into four equal areas （25 cm×25 cm; S-quadrats） and all plant species occurring in each of these smaller areas were identified and recorded. These data were summarized into frequency distributions and the percentage of S-quadrats containing a given species and the variance of each species were estimated. The power law was applied to these estimates. The power law was used to evaluate the spatial heterogeneity and frequency of occurrence for each species in the grassland community. The lightly grazed grassland exhibited high spatial heterogeneity （caused by large plant size）, the highest species diversity, and a high occurrence of S. baicalensis. In contrast, the heavily grazed grassland exhibited high spatial heterogeneity （caused by patchy populations of small plant size）, low species diversity, and a low occurrence of S. baicalensis. We judged that the heavily grazed grassland was overgrazed and exclusion of livestock from the degraded areas is necessary for recovery.
