Grazing Management Strategies Research Articles

Defoliation decreases soil aggregate stability by reducing plant carbon inputs and changing soil microbial communities

Soil aggregation and its stability are fundamental in ensuring soil function and ecosystem service provision, which can be greatly altered by ungulate disturbance, particularly the indirect effects from biomass removal by defoliation and direct effects from hoof trampling, but the mechanisms underlying the effect of defoliation and trampling on soil aggregation remains largely unexplored. Here, we conducted a 3-year manipulative experiment to investigate the effects of defoliation and trampling of ungulates and their interaction on soil aggregate stability in a semiarid grassland of Inner Mongolia, China. We found that defoliation rather than trampling dominantly affected soil aggregate stability. Defoliation disintegrated macroaggregates, reducing aggregate stability (-5 %), mainly attributed to the direct influence of a decline in plant inputs (aboveground biomass: −32 %) and the indirect effects of soil microbial biomass (-5 %). Moreover, compared to no defoliation plots, defoliation significantly decreased soil fungal diversity and altered fungal communities, particularly decreasing the relative abundance of Glomeraceae fungal taxa favorable to the formation of soil aggregates. Trampling only slightly attenuates the involvement of microorganisms (indirectly, −7 %) in aggregate formation by increasing soil compaction (directly, −4 %), and the positive effects from accelerating litter-derived C inputs due to trampling disturbance may counteract these limited negative effects. Our results highlight the negative effect of biomass removal by ungulates on soil aggregation, and suggest that the role of plant inputs and soil microbial properties on soil function and their correlation with soil aggregate stability needs to be explored under a diversity of grazing management strategies to refine management to improve soil conservation, C persistence and restore grasslands.

The LTAR-integrated grazing land common experiment at the Texas Gulf.

Extreme weather and climate events have become more frequent and directly affect the ecological structure and function of integrated grazing lands. While the Great Plains have experienced a long history of regular disturbances from drought and floods, grazing, and fires, the increased frequency and magnitude of these disturbances can reduce ecological resilience, largely depending on management practices. Alternative strategies designed to adaptively manage grazing land resources based on the ecology of the system should increase the resistance and resilience to disturbances when compared to prevailing practices. Determining the ecologic and economic value of alternative strategies will require long-term evaluations across large spatial scales. The Long-Term Agroecosystem Research Network has been established to evaluate the differences between alternative and prevailing practices among 18 strategically located sites and across decadal time scales throughout the continental United States. A key integrated grazing land site within this network is the Texas Gulf located at the Riesel Watersheds in the Blackland Prairie of Central Texas. At this study site, the differences between alternative and prevailing grazing management strategies are now being evaluated. The alternative strategy was designed using a combination of knowledge of the site and species ecology with modern-day tools and technologies. Alternatively, the prevailing practice implements a conventional year-round continuous grazing system with heavy reliance on hay and supplemental protein during winter. Results will provide grazing land managers with economically viable adaptive management choices for increasing ecological resilience following extreme and frequent disturbance events.

Impacts of grazing management strategies on forage canopy structure in multi-species pastures during the wet-dry transition period

The condition of pastures during the wet-dry transition period reduces livestock production since there is an increase in dead material and a reduction in green tissues. This study evaluated the influence of grazing management strategies on the structure of the forage canopy during the wet-dry transition period. The pastures were composed of Aruana guineagrass (Megathyrsus maximum Syn. Panicum maximum cv. Aruana) and three legumes: Macrotyloma (Macrotyloma axillare), Calopo (Calopogoinum mucunoides), and Stylo (Stylosanthes macrocephala + Stylosanthes capitata). The treatments corresponded to four forage canopy heights (15, 30, 45, and 60 cm), and the grazing management strategies involved steady or variable stocking rates with sheep. The experiment was conducted in a randomized complete block design with four replications totaling 16 experimental units (paddocks). The masses of grass leaf blades and stems were higher at heights of 45 and 60 cm (P = 0.002), while the proportion of dead material was smaller in these than in the short pastures (15 and 30 cm) (P = 0.0497). There was an increase in the proportion of dead material over the dry-water transition period. The presence of grass and legume leaves was higher in the upper stratum of tall pastures (45 and 60 cm) and the proportion of legumes did not differ between grazing management strategies (P > 0.05). These strategies were represented by canopy heights of 45 to 60 cm and showed more leaf mass, less dead material, and better pasture structure, so these parameters can be used during the wet-dry transition period.

Forage plants in grasslands with different topographies affect yak foraging preferences on the eastern Tibetan plateau.

Diet selection, a core problem of foraging behavior, is a nutritional adaptation strategy formed in the long-term natural selection process by grazing herbivores and is significant for the sustainable management of grassland. Studies have mainly focused on the impacts of the individual and whole community spatial characteristics and herbivore body status on herbivore foraging behavior; thus, the response and mechanism of forage plants in different terrains to the diet selection of grazing herbivores remains unclear. Therefore, in this study, forage plants (gramineae, cyperaceae, legume, forbs, edible shrubs, and community) in different topographies (terrace, riparian zones, shady slope, half shady slope, half sunny slope, sunny slope) on the eastern Tibetan plateau were selected to study changes in nutrient and mineral content characteristics of forage plants, as well as the difference in feeding bias of yaks for forage plants in different terrains by using an indoor cafeteria trial. A structural equation model was used to illustrate the impact of the forage plants in different terrains on the feeding bias of yak. The multi-criterion decision model TOPSIS showed that the nutritional value of gramineae was highest for the shaded slope, and that of cyperaceae and leguminosae was the highest for the terraces. The nutrient value of forbs and the whole community was highest for the sunny slope. Dry matter intake by yaks of leguminosae, forbs, and the whole plant community was significantly higher for terraces than for grasslands with other topographies, and all were significantly lower in riparian zones. Yak forage preference of leguminosae, forbs, and the whole community was the highest for the terrace and the lowest for the riparian zones. Structural equation modeling showed that for functional groups, the interactions between topography and functional groups were the drivers influencing yak forage preferences. Our study highlights the propensity of yaks to forage for plants in areas with different topographies. These results have provided a scientific basis for understanding the relationship between herbivores and plants in grasslands and for formulating scientific grazing management strategies, which are of considerable importance for sustainable grassland livestock husbandry.

7 Environmental sustainability of livestock systems in the southeastern U.S.: Opportunities and research gaps

Abstract According to the Environmental Protection Agency (EPA), enteric methane (CH4) was the second largest source of greenhouse gas emissions from agriculture in 2021 behind nitrous oxide emissions from soil management. Cattle production in the southeastern U.S. represent a significant source of enteric CH4. In 2021, 31.5% of all cattle derived enteric CH4 arose from the southeastern U.S., representing 43.3% of cow-calf, 27.4% of stocker, 23.1% of feedlot, and 12.1% of dairy derived enteric CH4, according to the EPA. Previous work has demonstrated that reducing CH4 emissions represents the most promising means to limit climate change in the short-term, due to the short atmospheric lifespan of CH4. As such, developing enteric CH4 mitigation strategies for southeastern cattle producers is imperative. Enteric CH4 mitigation strategies can be grouped into diet formulations (e.g., lipid additions; feeding more grains; protein source and inclusion), feed management (e.g., grain and forage processing; grazing management; forage species), rumen manipulations [e.g., feed additives (ionophores or inhibitors); secondary plant compounds (tannins, essential oils, saponins)], and breeding strategies (e.g., selecting for low CH4 emitters; selecting for low residual feed intake). Of these options, the direct CH4 inhibitors appear to be the most promising. The largest source of enteric CH4 from the southeastern U.S. is from cow-calf production, representing 71.6% of the total. Furthermore, a 13.6% reduction in enteric CH4 from the southeastern cow-calf herd would offset more emissions than a 100% reduction in the southeastern dairy, stocker, or feedlot sectors. Despite the large gains in emission reductions that could be achieved by focusing on enteric CH4 mitigation strategies from southeastern pastoral systems, there has been relatively little research efforts in this area. For example, there has yet to be any investigation into the mitigation potential of CH4 inhibitors when fed to grazing cattle. This is especially important, because the mitigation potential of inhibitors is likely much greater for grazing than for confined fed cattle. Additionally, there are limited and aging research into grazing management strategies effects on enteric CH4 emissions. There also exists a gap-in-knowledge of how common (e.g., supplementation) or changes in management (e.g., selecting for smaller mature cow sizes) practices could potentially influence enteric CH4 emissions. Future research is still needed to further develop enteric CH4 mitigation strategies, with efforts needed in grazing systems, especially for the southeastern U.S.

SustAinimal Grazing Living Lab – a survey of grazing management on dairy farms in northern Sweden

ABSTRACT A survey was conducted on 302 Sweden dairy farms (response rate 98%) to identify grazing and grassland management strategies and main challenges to grazing in northern Sweden. The most common grazing strategy on all dairy farms was continuous grazing (59%) followed by rotational grazing (45%), while organic dairy farms preferentially adopted rotational grazing (69%). The main challenges reported in grazing dairy cows on temporary grasslands on conventional farms were trampling damage and seasonal variations in grass growth, while for organic dairy farmers, the primary challenge was weed control. Only a few farms had grazing on semi-natural grasslands. Future sustainable grazing should focus on optimising grazing strategy in relation to on-farm grazing locations and nutrient supply for high-yielding dairy cows.

Impact of livestock grazing management on carbon stocks: a case study in sparse elm woodlands of semi-arid lands.

Livestock grazing is a widespread practice in human activities worldwide. However, the effects of livestock grazing management on vegetation carbon storage have not been thoroughly evaluated. In this study, we used the system dynamic approach to simulate the effects of different livestock grazing management strategies on carbon stock in sparse elm woodlands. The livestock grazing management strategies included rotational grazing every 5 years (RG5), prohibited grazing (PG), seasonal prohibited grazing (SPG), and continuous grazing (CG). We evaluated the carbon sequestration rate in vegetation using logistical models. The results showed that the carbon stock of elm trees in sparse woodlands was 5-15 M g ha-1. The values of the carbon sequestration rate were 0.15, 0.13, 0.13, and 0.09 Mg C ha-1 year-1 in RG5, PG, CG, and SPG management, respectively. This indicates that rotational grazing management might be the optimal choice for improving vegetation carbon accumulation in sparse woodlands. This study contributes to decision-making on how to choose livestock grazing management to maintain higher carbon storage.

Grazing reduced greenhouse gas fluxes in Inner Mongolia grasslands: A meta-analysis

Grazing exerts a significant influence on greenhouse gases (GHGs) fluxes within temperate grasslands. While previous studies have explored the impact of varying grazing intensities on GHGs fluxes in meadow steppe, typical steppe, and desert steppe, there remains a knowledge gap regarding how grazing intensities affect GHGs fluxes across different grassland types and seasonal variations. In this study, we conducted a meta-analysis of Inner Mongolia grasslands involving 38 published reports and aggregating 143, 160, and 118 records for the CO2, CH4, and N2O, respectively. Our results demonstrated that grazing reduced annual mean CO2 emission, CH4 uptake, and N2O emission by 15.29%, 10.56%, and 24.73%, respectively (P < 0.05). Specifically, during the freeze-thaw period, grazing induced a decrease of 28.06% and 58.41% in CH4 uptake and N2O emissions, respectively, compared to ungrazed treatments (P < 0.05). Further dissecting the impact, we found that grazing reduced CO2 emissions in desert steppe, typical steppe, and meadow steppe by 20.28%, 15.54%, and 11.79%, respectively. In addition, grazing decreased CH4 uptake in typical steppe by 15.14% and decreased N2O emission in typical steppe, meadow steppe, and sown pasture by 20.25%, 24.18%, 52.91%, respectively. Crucially, the alteration in plant biomass due to grazing-induced changes underlying drivers that govern the responses of GHGs fluxes. These results furnish compelling evidence that grazing, particularly in non-growing season, holds the potential to mitigate grassland GHGs fluxes in temperate grasslands. Our results can deepen the understanding of the grazing effects on GHGs and offer valuable insights for refining grazing management strategies in pastoral regions.

Effect of grazing management strategies on the vegetation parameters and soil nutrients in alpine Kobresia pygmaea meadow on the northeastern Qinghai–Tibetan Plateau

Understanding the impact of grazing management strategies on alpine meadow is of fundamental importance for grassland conservation. However, the vegetation and soil properties in response to the different grazing management strategies implemented on Kobresia pygmaea meadow remains elusive. In this study, a medium-term field experiment with three grazing management strategies (free grazing, FG; no grazing, NG; and reduced grazing, RG) was conducted. The results revealed that the total aboveground biomass (AGB), vegetation cover and litter biomass increased significantly under NG treatment, whereas the total belowground biomass (BGB) decreased significantly in NG plot. Furthermore, the responses of plant functional groups to different grazing management strategies were varied. The AGB of grass increased remarkably under NG treatment compared to FG plot, whereas there were no obvious change in AGB of the sedge, legume, and forb groups. The concentrations of the soil available phosphorus (AP) and ammonia nitrogen (NH4+-N) of RG and FG were considerably different at the 0–5 cm soil layers. In contrast, the soil C:N ratios in all soil layers were similar among the three grazing management strategies. It is worth noting that the soil AP concentration was positively correlated with the total AGB. More importantly, the results supported the functional equilibrium hypothesis for AGB versus BGB, which is based on the unique biological characteristics of K. pygmaea meadow. Our study provides valuable insights into the response of alpine meadow to grazing management strategies and can thus provide guidance for designing management strategies for degraded alpine meadow.

Assessing regeneration strategies for sustaining intensively used Chilgoza pine-dominated community forests in Afghanistan

Income from Chilgoza pine (Pinus gerardiana) nut harvests, grazing, and the collection of firewood support forest communities within Afghanistan's Eastern Forest Complex. Persistent instability, frequent incidence of armed conflict, limited capacity of Indigenous communities, and inaccessibility to scientific expertise on forest regeneration limit options for addressing forest degradation. Representatives from forest communities in 16 districts in Khost, Paktia, and Paktika Provinces were surveyed to assess community user perceptions of Chilgoza pine regeneration status, forest protection, and acceptability of potential regeneration strategies (rotational stand harvesting, group seed tree protection, individual seed tree protection, partial cone harvesting, and integrated method). Human activity management, primarily via fine systems and forest guards, was widely reported and was regarded as important in managed forests. Respondents who reported current implementation of regeneration methods were more likely to regard natural regeneration as important and most regarding natural regeneration as very important reported the use of partial cone crop harvest as the prevailing regeneration method. Among proposed strategies, partial cone harvesting was the most frequently chosen option where regeneration was regarded as very or somewhat important. In light of the previously reported decline of forests under prevailing management practices, these results indicate a general awareness of regeneration as a forest management issue but also a significant gap among forest users in identifying the limitations of partial cone crop harvesting without additional protection for seedlings, as a potential remedy. We offer integrated rotational harvesting and grazing management strategies as a means to promote sound silviculture practices and provide a next step for community-based forest management to sustain Chilgoza pine. The context of this work in a region where tribal politics has limited outsider input allows it to serve as a model to address natural resource management issues in similar conflict-prone settings.

Canopy height impact on legume mass and Megathyrsus maximus tiller dynamics in mixed pastures

ABSTRACT The use of grazing management strategies can influence canopy structure and the permanence of legumes. The objective of this work was to evaluate the determination of forage canopy heights as a grazing management strategy regarding herbage mass composition and tiller population dynamics in multispecies pastures comprising Megathyrsus maximus cv. Aruana and the legumes Macrotyloma axillare, Calopogonium mucunoides and Stylosanthes spp. Four treatments, defined by canopy heights of 15, 30, 45 and 60 cm, were evaluated in a randomised block design with four replications. The evaluations were performed under continuous stocking with sheep. Taller pastures (45 and 60 cm) contained greater (P < 0.05) total herbage mass of Aruana leaves and stems and also higher mass of legumes than smaller pastures (15 and 30 cm). The grass tiller population density was different between heights (P < 0.05) of 2.71, 2.02, 1.97 and 1.47 tillers/m2 for heights of 15, 30, 45 and 60 cm, respectively. The tiller appearance rate was highest in tall pastures (P < 0.05) and the lowest rate and stability index were found in 15 cm pastures. Aruana guineagrass and forage legumes can be managed in the height range of 30–60 cm under continuous stocking.

Enabling Regenerative Agriculture Using Remote Sensing and Machine Learning

The emergence of cloud computing, big data analytics, and machine learning has catalysed the use of remote sensing technologies to enable more timely management of sustainability indicators, given the uncertainty of future climate conditions. Here, we examine the potential of “regenerative agriculture”, as an adaptive grazing management strategy to minimise bare ground exposure while improving pasture productivity. High-intensity sheep grazing treatments were conducted in small fields (less than 1 ha) for short durations (typically less than 1 day). Paddocks were subsequently spelled to allow pasture biomass recovery (treatments comprising 3, 6, 9, 12, and 15 months), with each compared with controls characterised by lighter stocking rates for longer periods (2000 DSE/ha). Pastures were composed of wallaby grass (Austrodanthonia species), kangaroo grass (Themeda triandra), Phalaris (Phalaris aquatica), and cocksfoot (Dactylis glomerata), and were destructively sampled to estimate total standing dry matter (TSDM), standing green biomass, standing dry biomass and trampled biomass. We invoked a machine learning model forced with Sentinel-2 imagery to quantify TSDM, standing green and dry biomass. Faced with La Nina conditions, regenerative grazing did not significantly impact pasture productivity, with all treatments showing similar TSDM, green biomass and recovery. However, regenerative treatments significantly impacted litterfall and trampled material, with high-intensity grazing treatments trampling more biomass, increasing litter, enhancing surface organic matter and decomposition rates thereof. Pasture digestibility and sward uniformity were greatest for treatments with minimal spelling (3 months), whereas both standing senescent and trampled material were greater for the 15-month spelling treatment. TSDM prognostics from machine learning were lower than measured TSDM, although predictions from the machine learning approach closely matched observed spatiotemporal variability within and across treatments. The root mean square error between the measured and modelled TSDM was 903 kg DM/ha, which was less than the variability measured in the field. We conclude that regenerative grazing with short recovery periods (3–6 months) was more conducive to increasing pasture production under high rainfall conditions, and we speculate that – in this environment - high-intensity grazing with 3-month spelling is likely to improve soil organic carbon through increased litterfall and trampling. Our study paves the way for using machine learning with satellite imagery to quantify pasture biomass at small scales, enabling the management of pastures within small fields from afar.

Effects of grazing management and concentrate supplementation on intake and milk production of dairy cows grazing orchardgrass

In pasture-based dairy systems, grazing management strategies have focused mainly on achieving a high herbage harvest per hectare, whereas strategies oriented to maximizing the intake rate of herbage have been recently explored. The objectives of the study were (i) to evaluate the herbage nutritional value, intake and milk production per animal and per hectare of mid-lactation Holstein dairy cows grazing orchardgrass (Dactylis glomerata) in response to grazing management strategies that prioritize either herbage harvest per hectare or herbage intake rate, and (ii) to assess whether concentrate supplementation affects this response. The experiment was conducted in Uruguay using twenty-four mid-lactation Holstein dairy cows grazing orchardgrass under rotational stocking over an 81-day period. The experimental design was a randomized complete block with a 2 × 2 factorial arrangement consisting of two grazing management strategies [i.e. “high intake rate” (HIR) with pre- and post-grazing sward target heights of 21 and 13 cm, respectively, vs. “high herbage harvest per hectare” (HHH) with a pre-grazing target of 3.5–4 leaves per tiller and a post-grazing target of minimum leaf area corresponding to sward heights between 7 and 11 cm] in combination with concentrate supplementation levels of 0 (CS0) or 4 (CS4) kg of dry matter/cow per day. Sward height, number of leaves, herbage morphological and chemical composition, body weight (BW), body condition score (BCS), feed intake, and milk production per cow and per hectare were measured. Statistical analyses were performed using linear mixed models. Compared to cows under HHH, cows under HIR grazed herbage with greater nutritional value and achieved a greater feed intake and greater milk production per cow (P < 0.05), regardless of concentrate supplementation level. Conversely, under HHH milk production per hectare was marginally greater (P < 0.10) and milk solids production per hectare was greater (P < 0.05). Yet, cows under HHH lost BCS when were managed without supplementation (P < 0.05). In conclusion, HIR grazing management is an effective option for grazing dairy production systems that seek to maximize individual productivity of high-producing cows. On the other hand, HHH grazing strategies remain relevant to dairy farm businesses in which profit is driven by production per hectare. Yet, high producing dairy cows under this strategy are likely to lose BCS if not supplemented.

109 Invited Talk: Grazing Management and Stocking Strategy Decisions for Pasture-Beef Systems: Experimental Confirmation vs Testimonials and Perceptions

Abstract The primary objectives of forage-based livestock grazing systems are to enhance sustainability of pastures and cattle production, and to maintain economic stability in the presence of changes in input costs and returns. Grazing management strategies and implementation vary for adapted forages according to vegetational-hardiness zones, livestock production objectives, and manager preferences for grazing systems, stocking rates, and stocking methods. Stocking methods are strategies or techniques to manipulate grazing animals in space and time and may be considered as variations of continuous or rotational stocking. In many stocking method discussions, the debates are often focused on experimental confirmational data vs testimonials and perceptions. Acceptable methodology and statistical analyses of grazing experimentation on continuous vs rotational stocking provides repeated measures of forage nutritive value, forage mass, grazing intensity, and stocking rate on gain per animal, gain per unit land area. Additional measurements may include effects on forage stand maintenance and soil nutrient analyses-status. Recent adaptations of mob stocking and intensive rotational grazing via popular press and consultants have received acclaims for methods to enhance ecosystem services, soil health, and other non-experimentally documented attributes. Managers may adopt these testimonials of stocking methods of 60 days or more deferment based on their perception of protecting and enhancing the environment rather than logic of seeking experimental evidence. However, when given a choice of forage available for consumption, cattle select more than 80% of their diet as leaves. Thus, with respect to average daily gain per animal (ADG), only a small percentage of pasture studies have shown an advantage for rotational stocking. The lack of ADG was attributed to reduced nutritive value of forage available for selection during the residence time. Selecting management and stocking strategies for optimum utilization for forage produced, individual animal performance, and overall gain per unit land area has led to flexible grazing systems. These grazing systems may not be “hardcore rotationally, time-scheduled stocked,” but they do involve multiple pastures with strategies to incorporate movement of cattle based on current paddock forage status and forage mass estimates for desired animal performance. Grazing management strategies control the degree of intensity of beef cattle production based on level of economic risk and desired-expected environmental stewardship goals. Of all the strategies that management may adopt for grazing, the primary factor that controls resultant sustainability of pastures is that of grazing intensity as measured by stocking rate or forage height-density. Implementing revised or new management strategies requires attention to detail and the use of data-results-recommendations from comparative experiments conducted by a recognized source without conflict of interest in the method promoted.

Forage intake and nitrogen metabolism of beef cattle grazing palisadegrass‐calopo mixed pasture managed using canopy light interception

AbstractTo define the best grazing management strategy, it is important to assess animals' responses to variations in the structure and composition of tropical forages. This 2‐year study evaluated animal response to Marandu palisadegrass (Urochloa brizantha)‐calopo (Calopogonium mucunoides) mixed pastures managed under rotational grazing. Treatments consisted of three defoliation frequencies defined by rest periods interrupted at 90% (90LI), 95% (95LI) and 100% (100LI) of photosynthetically active radiation interception (LI). The stubble post‐grazing height target was 15 cm. Statistical difference was declared at p &lt; .10. The 100LI had lowest crude protein (CP) and in vitro dry matter digestibility (IVDDM) for the Marandu palisadegrass (p = &lt;.001 both) and calopo (p = .003 and p = .067, respectively). Also, the OM digestibility decreased 7.0% in the 100LI condition than 90LI and 95LI treatment (p = .005). There was no difference in forage, grass, and legume intakes between the treatments (p &gt; .10). The 100LI treatment decreased CP intake from grass in 33.3% (p = &lt;.001) compared to other treatments. Greatest production of microbial N (p = .093) occurred with the 90LI treatment. The CP/digestible organic matter (DOM) ratio, urinary N excretion and retained N were lowest in the 100LI treatment (p = &lt;.001, p = .007 and p = .014, respectively). The recommendation for grazing between 90 and 95% of LI is recommended because of greater CP intake and N utilization for the animals and improved the nutritive value of Marandu palisadegrass and calopo mixed pastures.

Effects of grazing and precipitation addition induced by functional groups on the relationship between aboveground biomass and species richness of a typical steppe

Several studies have explored the influence of grazing or precipitation addition (PA), two important components of human activities and global climate change on the structure and function of communities. However, the response of communities to a combination of grazing and PA remains largely unexplored. We investigated the impact of grazing and PA on the relationship between aboveground biomass (AGB) and species richness (SR) of communities in three-year field experiments conducted in a typical steppe in the Loess Plateau, using a split-plot design with grazing as the main-plot factor and PA as the split-plot factor. AGB and SR have response threshold value to PA, which was decreased by grazing for AGB, but increased for SR. This indicates that implementing grazing management strategies is conducive to strengthening the protection of biodiversity in arid and semi-arid grasslands. Grazing promoted the AGB-SR coupling of the community by increasing the SR of medium drought tolerance (MD), low drought tolerance, and grazing tolerant functional groups. Grazing also accelerated the AGB-SR decoupling of the community by changing the AGB of high drought tolerance, MD, high grazing tolerance, and medium grazing tolerance functional groups. PA mediated changes in MD and SR of both drought and grazing tolerant functional groups and AGB of low grazing tolerance promoted the coupling of AGB-SR of the community. The Two-dimension functional groups classification method reflects the changes of AGB and SR in communities more reasonable than the division of single-factor functional groups.

A Geospatial Modelling Approach to Understand the Spatio-Temporal Impacts of Grazing on Soil Susceptibility to Erosion

Grazing management to reduce soil erosion is paramount for preserving and enhancing grassland health under pastoral livestock production systems. However, as the focus of these production systems is to increase productivity, the inclusion of the soil and its complexity in grazing management has been usually neglected. Detailed consideration of the soil spatio-temporal susceptibility to erosion may be best approached with simulation modelling. To understand and explore the spatio-temporal impact of grazing strategies on soil surface erosion, this work used a geospatial model approach in a high-country pastoral livestock production system in New Zealand as a case study. We modelled 45 scenarios characterized by different stock densities and occupation periods applied for each season of the year and for different livestock types: sheep, beef, and deer, producing a total of 540 scenarios. In addition, we included scenarios to represent ungrazed pastures for each season and the current grazing management of the case study station as the baseline for comparisons (resulting in a total of 545 scenarios). Spatio-temporal variation of natural soil superficial erosion from ungrazed pastures appears to be more relevant than the impact of manipulating grazing intensity and indicates that paddocks in our study area have different capacities to support grazing which also changes during seasons. Increases in occupation period seem more detrimental to soil erosion compared to increases in stock density, and cattle are the most detrimental stock type compared to sheep and deer. Our results suggest that grassland health can be enhanced in LUMGS by applying context-adjusted grazing management strategies according to the station spatio-temporal heterogeneity and susceptibility to erosion.

Grazing reduces plant sexual reproduction but increases asexual reproduction: A global meta-analysis

Grazing affects grasslands worldwide. However, the global patterns and general mechanisms of how grazing affects plant reproductive traits are poorly understood, especially in the context of different climates and grazing duration. We conducted a meta-analysis of 114 independent grazing studies worldwide that measured plant reproductive traits in grasslands. The results showed that the number of tillers of plant increased under grazing. Grazing did not affect the number of reproductive branches of forbs, but significantly reduced the number of reproductive branches of grasses. Grazing increased the number of vegetative branches of all plants and reduced the proportion of reproductive branches. Grazing significantly reduced the number of flowers in forbs. Seed yield in the two plant functional groups was reduced compared with no-grazing.Under grazing, the sexual reproduction of grasses decreased much more substantially than that of forbs. This may be due to biomass allocation pattern of grasses under grazing (i.e., belowground versus aboveground). Under grazing, plants tended to adopt rapid, low-input asexual reproduction rather than long-term, high-risk sexual reproduction. This study represents the first large-scale evaluation of plant reproductive trait responses under grazing and demonstrates that grazing inhibits sexual reproduction and promotes asexual reproduction. The effect of grazing on plant sexual reproduction was influenced by grazing intensity, mean annual precipitation, and grazing duration. These results will assist in the development of sustainable grazing management strategies to improve the balance between human welfare and grassland ecosystem health.

Effects of Livestock Exclusion on Stream Habitat and Aquatic Biota: A Review and Recommendations for Implementation and Monitoring

AbstractTo inform riparian restoration, research, and monitoring and to provide management recommendations, we reviewed published studies evaluating the physical and biological effectiveness of livestock exclusion and grazing reduction on various metrics in riparian and aquatic areas. We identified 95 North American studies that reported the effects of livestock grazing reduction on physical habitat (channel morphology, mesohabitats, substrate, and bank stability), biological assemblages (riparian vegetation, macroinvertebrates, fish, and birds), and water quality metrics (temperature, nitrates, phosphorus, and turbidity). Most studies reported that methods to reduce or exclude livestock decreased channel width, width‐to‐depth ratio, bank erosion, soil bulk density, bare ground, water temperature, nitrogen, and phosphorus and increased riparian vegetation (cover, height, productivity, biomass, and abundance), riparian bird abundance, and young‐of‐the‐year fishes. Results for channel depth, instream substrate, mesohabitats, water depth, juvenile and adult fishes, and macroinvertebrates showed no consistent response to exclusion. Project success was influenced by the time since exclusion; whether there was complete exclusion or continued grazing; and local climate, geology, and soils. Apart from bank erosion and stability, most of the physical and biological metrics took more than a decade to respond to livestock exclusion. However, coupling exclusion with planting and other restoration measures decreased the recovery time. Complete exclusion of livestock produced more consistent improvements in riparian condition and other metrics than rest–rotation or other grazing management strategies. Understanding how physical and biological metrics respond to livestock exclusion will require (1) focused, long‐term studies using before–after or before–after, control–impact designs; and (2) monitoring of metrics that most consistently respond to exclusion. Ultimately, the design of exclusions should be driven by local climate, geology, biophysical conditions, and management history. Our results highlight the need for watershed‐scale approaches to excluding livestock from broad areas and the need for implementation monitoring to ensure that fencing and other exclusion measures continue to exclude livestock and produce the desired responses.

Grazing management and stocking strategy decisions for pasture-based beef systems: experimental confirmation vs. testimonials and perceptions

Abstract Grazing management and stocking strategy decisions involve the manipulation of grazing intensity, grazing frequency, and timing of grazing to meet specific objectives for pasture sustainability and economic livestock production. Although there are numerous stocking systems used by stakeholders, these methods may be broadly categorized as either continuous or some form of rotational stocking. In approximately 30 published experiments comparing continuous vs. rotational stocking, there was no difference in liveweight gain per animal between stocking methods in 66% of studies. There was no difference in gain per hectare between methods in 69% of studies, although for gain per hectare the choice of fixed or variable stocking rate methodology affected the proportion (92% for fixed; 50% for variable). Despite these experimental results showing limited instances of difference between rotational and continuous stocking, rotational strategies (e.g., “mob stocking” or “regenerative grazing”) have received what appears to be unmerited acclaim for use for livestock production. Many proposed “mob stocking” or “regenerative grazing” systems are based on philosophies similar to high intensity-low frequency stocking, including provision for &amp;gt;60 d of rest period from grazing. In addition, grazing management practitioners and stakeholders have voiced and proposed major positive benefits from rotational stocking, “mob stocking”, or “regenerative grazing” for soil health attributes, carbon sequestration, and ecosystem services, without experimental evidence. The perceptions and testimonials supporting undefined stocking systems and methods have potential to mislead practitioners and result in economic disservices. Thus, we suggest that scientists, extension-industry professionals, and producers seek replicated experimental data as the basis for predicting outcomes of grazing decisions.