Unraveling spatial heterogeneity of soil legacy phosphorus in subtropical grasslands.

Humans have profoundly altered phosphorus (P) cycling across scales. Agriculturally driven changes (e.g., excessive P-fertilization and manure addition), in particular, have resulted in pronounced P accumulations in soils, often known as "soil legacy P." These legacy P reserves serve as persistent and long-term nonpoint sources, inducing downstream eutrophication and ecosystem services degradation. While there is considerable scientific and policy interest in legacy P, its fine-scale spatial heterogeneity, underlying drivers, and scales of variance remain unclear. Here we present an extensive field sampling (150-m interval grid) and analysis of 1438 surface soils (0-15 cm) in 2020 for two typical subtropical grassland types managed for livestock production: Intensively managed (IM) and Semi-natural (SN) pastures. We ask the following questions: (1) What is the spatial variability, and are there hotspots of soil legacy P? (2) Does soil legacy P vary primarily within pastures, among pastures, or between pasture types? (3) How does soil legacy P relate to pasture management intensity, soil and geographic characteristics? and (4) What is the relationship between soil legacy P and aboveground plant tissue P concentration? Our results showed that three measurements of soil legacy P (total P, Mehlich-1, and Mehlich-3 extractable P representing labile P pools) varied substantially across the landscape. Spatial autoregressive models revealed that soil organic matter, pH, available Fe and Al, elevation, and pasture management intensity were crucial predictors for spatial patterns of soil P, although models were more reliable for predicting total P (68.9%) than labile P. Our analysis further demonstrated that total variance in soil legacy P was greater in IM than SN pastures, and intensified pasture management rescaled spatial patterns of soil legacy P. In particular, after controlling for sample size, soil P was extremely variable at small scales, with variance diminished as spatial scale increased. Our results suggest that broad pasture- or farm-level best management practices may be limited and less efficient, especially for more IM pastures. Rather, management to curtail soil legacy P and mitigate P loading and losses should be implemented at fine scales designed to target spatially distinct P hotspots across the landscape.

Simulating adaptive grazing management on soil organic carbon in the Southeast U.S.A. using MEMS 2.

Grazing lands play a significant role in global carbon (C) dynamics, holding substantial soil organic carbon (SOC) stocks. However, historical mismanagement (e.g., overgrazing and land-use change) has led to substantial SOC losses. Regenerative practices, such as adaptive multi-paddock (AMP) grazing, offer a promising avenue to improve soil health and help combat climate change by increasing SOC accrual, both in its particulate (POC) and mineral-associated (MAOC) organic C components. Because adaptive grazing patterns emerge from the combination of different levers such as frequency, intensity, and timing of grazing, studying AMP grazing management in experimental trials and representing it in models remains challenging. Existing ecosystem models lack the capacity to predict how different adaptive grazing levers affect SOC storage and its distribution between POC and MAOC and along the soil profile accurately. Therefore, they cannot adequately assist decision-makers in effectively optimizing adaptive practices based on SOC outcomes. Here, we address this critical gap by developing version 2.34 of the MEMS 2 model. This version advances the previous by incorporating perennial grass growth and grazing submodules to simulate grass green-up and dormancy, reserve organ dynamics, the influence of standing dead plant mass on new plant growth, grass and supplemental feed consumption by animals, and their feces and urine input to soil. Using data from grazing experiments in the southeastern United States and experimental SOC data from two conventional and three AMP grazing sites in Mississippi, we tested the capacity of MEMS 2.34 to simulate grass forage production, total SOC, POC, and MAOC dynamics to 1-m depth. Further, we manipulated grazing management levers, i.e., timing, intensity, and frequency, to do a sensitivity analysis of their effects on SOC dynamics in the long term. Our findings indicate that the model can represent bahiagrass forage production (BIAS = 9.51 g C m-2, RRMSE = 0.27, RMSE = 65.57 g C m-2, R2 = 0.72) and accurately captured the dynamics of SOC fractions across sites and depths (0-15 cm: RRMSE = 0.05; 15-100 cm: RRMSE = 1.08-2.07), aligning with patterns observed in the measured data. The model best captured SOC and MAOC stocks across AMP sites in the 0-15 cm layer, while POC was best predicted at-depth. Otherwise, the model tended to overestimate SOC and MAOC below 15 cm, and POC in the topsoil. Our simulations indicate that grazing frequency and intensity were key levers for enhancing SOC stocks compared to the current management baseline, with decreasing grazing intensity yielding the highest SOC after 50 years (63.7-65.9 Mg C ha-1). By enhancing our understanding of the effects of adaptive grazing management on SOC pools in the southeastern U.S., MEMS 2.34 offers a valuable tool for researchers, producers, and policymakers to make AMP grazing management decisions based on potential SOC outcomes.

Time budgets differ in horses during continuous and space-restricted rotational grazing.

Horses can become obese and develop related health issues such as laminitis from excessive grazing on high-quality pasture grass; limiting pasture intake can allow weight loss to occur. The objective of this study was to determine the effect of space-restricted rotational grazing on body weight (BW) and time budgets in horses. Eight mature geldings and mares with maintenance-only requirements were randomly assigned to either a space-restricted rotational grazing group (SRG; BW 512 ± 6 kg; n = 4) or a continuous grazing group (CG; BW 517 ± 49 kg; n = 4) for 42 d SRG horses grazed an area with dimensions to provide 80-90 % of mean digestible energy requirement for the 4 horses over a 7-d grazing period; whereas, the CG horses continuously grazed similar non-toxic endophyte-infected tall fescue pasture providing greater than maintenance requirements for the 42 d Horses in the SRG group were moved to a new area every 7 d for 6 weeks. On d 7 at 1600 h of each week, horses were brought inside, and feed was withheld overnight. At 0700 h the next day, BWs were recorded prior to turnout. Observers recorded behaviors simultaneously on SRG and CG horses every six minutes throughout the day three days per week according to an ethogram. This included 30 s scans of all horses. Proportion of grazing and standing had an inverse relationship. Proportion of grazing was affected by the treatment by time interaction, which grazing was displayed more in SRG than CG during weeks 2 and 3, and then reversed weeks 4, 5 and 6.

Pyric herbivory decreases soil denitrification despite increased nitrate availability in a temperate grassland.

Pyric herbivory, the combination of controlled burning and targeted grazing, is an effective strategy for restoring abandoned, shrub-encroached rangelands to open ecosystems. This practice may impact soil nitrogen pools by altering soil nitrification and denitrification rates, and may lead to an increase of nitrogen losses through nitrate leaching and N-gas emissions. This research, located in the south-western Pyrenees, investigated the effects of pyric herbivory on soil nitrification and denitrification potentials and mineral nitrogen content in a gorse-encroached temperate rangeland six months after the burning was implemented. The study included three treatments: high-severity burning plus grazing, low-severity burning plus grazing, and unburned and ungrazed areas (control). We measured soil nitrification and denitrification potentials (net and gross), the limitation of denitrifiers by nitrogen or organic carbon, and the abundance of nitrite- and nitrous oxide-reducing bacteria. Additional soil and vegetation data complemented these measurements. Results showed that pyric herbivory did not significantly affect nitrification potential, which was low and highly variable. However, it decreased gross denitrification potential and nitrous oxide reduction to dinitrogen in high-severely burned areas compared to the control. Denitrification rates directly correlated with microbial biomass nitrogen, soil organic carbon, soil water content and abundance of nirS-harbouring bacteria. Contrary to the expected, soil nitrate availability did not directly influence denitrification despite being highest in burned areas. Overall, the study suggests that pyric herbivory does not significantly affect mid-term nitrification rates in temperate open ecosystems, but may decrease denitrification rates in intensely burned areas. These findings highlight the importance of assessing the potential impacts of land management practices, such as pyric herbivory, on soil nutrient cycling and ecosystem functioning.

Application of remote sensing to understand the role of Galician feral horses in the biomass reduction of a shrub-grassland-dominated landscape.

Galician forests in northwestern Spain are subject to frequent wildfires with high environmental and economic costs. In addition, due to the consequences of climate change, these fires are becoming more virulent, occurring throughout the year, and taking place in populated areas, in some cases involving the loss of human life. Therefore, forest fire prevention is even more relevant than mitigating its consequences. Given the costs involved in forestry work, alternative measures to reduce fuel load and create vegetation gaps are needed. One involves grazing by an endemic species of feral horses (Equus ferus atlanticus) that feed on thicket-forming gorse (Ulex europaeus). In a 100-ha forest fenced study area stocked with 11 horses, four 50 m2 enclosed plots prevented the access of these wild animals to the vegetation, with the aim of manipulating their impact on the reduction of forest biomass. The measurement of biomass volumes is an important method that can describe the assessment of wildfire risks, unfortunately, high-resolution data collection at the regional scale is very time-consuming. The best result can be using drones (unmanned aerial vehicles - UAVs) as a method of collecting remotely sensed data at low cost. From September 2018 to November 2020, we collected information about aboveground biomass from these four enclosed plots and their surrounding areas available for horses to forage, via UAV. These data, together with environmental variables from the study site, were used as input for a fire model to assess the differences in the surface rate of spread (SROS) among grazed and ungrazed areas. Our results indicated a consistent but small reduction in the SROS between 0.55 and 3.10 m/min in the ungrazed enclosured plots in comparison to their grazed surrounding areas (which have an SROS between 15 and 25 m/min). The research showed that radar remote sensing (UAV) can be used to map forest aboveground biomass, and emphasized the importance and role of feral horses in Galicia as a prevention tool against wildfires in gorse-dominated landscapes.

The impact of grazing on biodiversity and forest succession in the Brazilian dry forest region is constrained by non-equilibrium dynamics.

The impacts of grazing on rangelands have historically been studied within the framework of the equilibrium model, which predicts significant impacts of grazing on ecosystems. However, in recent decades, studies have observed a non-equilibrium pattern, suggesting that abiotic factors play a primary role compared to grazing. These studies are primarily focused on rangelands, despite animal husbandry occurring in other biomes, such as seasonally dry tropical forests. Our study examines the influence of goat grazing on biodiversity and forest succession in the Brazilian dry forest (Caatinga). Considering its high interannual precipitation variability, we hypothesize a response that aligns with the non-equilibrium paradigm. We established a gradient of grazing intensity and history in areas at different stages of vegetation succession. A survey of tree - shrub and herbaceous species was conducted at each site and the biomass of both strata was quantified. Linear mixed models and Permanova were employed to assess differences in richness, composition, structure, and biomass among the areas. Our results suggest that grazing (history and intensity) and forest fallow age did not affect species richness, but only species composition. Low and high grazing intensity drive ecosystems toward similar compositions, which align with the non-equilibrium model predictions. Biomass in the herbaceous layer remained unaffected by grazing history, intensity, or forest fallow age, whereas woody biomass was influenced by grazing intensity in older forest fallows. Although trees in low-intensity grazing sites were significantly taller compared to those in other levels, overall, grazing did not disrupt the natural succession process. Older forest fallows exhibited greater diversity and higher basal area compared to new forest fallows, irrespective of grazing intensity. Our findings suggest that: a) grazing has minimal effects on biodiversity and biomass due to non-equilibrium dynamics, and b) with appropriate management, grazing can coexist with the conservation of the Caatinga.

Camera-trapping: wild and domestic species occurrences in three Pyrenean pastures.

Background: The co-existence between brown bears (Ursusarctos Linnaeus, 1758) and farmers in the Pyrenees has been a major concern for several decades. The bear's depredation on livestock has multiple implications for traditional practices of extensive grazing and calls for a better understanding of the various ways in which humans and non-humans interact across different territories. The present dataset stems from "The Pastoralism and Bears in the Pyrenees" research project led by the GEODE laboratory (UMR 5602 CNRS-UT2J) in partnership with the Association Dissonances. Focusing on three summer pastures as places of encounter, this project proposes to explore the definition of co-existence, based on context-dependent and constantly evolving relationships between bears and pastoralists. As part of an interdisciplinary approach combining animal geography and ecology, the spatio-temporal activity of the different species was explored using a network of 118 camera traps. New information: The 118 camera traps were installed on the three summer pastures while livestock was present in the mountains between May and October, from 2021 to 2023 and were set in a 400 m ✕ 400 m grid covering a total area of around 2,000 ha. The present dataset contains 57,928 occurrences of 22 taxon categories, including 19 identified species, two family categories (equids and mustelids) and one class category (birds). As pastoral activity is significantly present in these areas, livestock (sheep (Ovisaries Linnaeus, 1758), equids, cows (Bostaurus Linnaeus, 1758) and goats (Caprahircus Linnaeus, 1758)) account for 16,207 occurrences across the three pastures. The three main wild species captured over the three years and three pastures were the red deer (Cervuselaphus Linnaeus, 1758; 9,517 occurrences), red fox (Vulpesvulpes Linnaeus, 1758; 9,400 occurrences) and wild boar (Susscrofa Linnaeus, 1758; 4,016 occurrences).Data are aggregated at the grid scale. Nonetheless, the exact locations of each camera trap as well as the photos can be requested from us.

The interaction of genes and environment on percent of juniper in the diet of goats divergently selected for high or low juniper consumption.

Diet selection and preference by grazing animals are determined by genetic and environmental factors that interact and affect their efficacy for managing vegetation as targeted grazers and developing animals adapted to local grazing environments. The effect of the rearing environments on the consumption of juniper (Juniperus spp.) by goats that for 15 years were divergently selected for high (J+) or low (J-) percent juniper in their diet was investigated. To test the effect of rearing environment, at the end of the breeding season, pregnant does from both selection lines were grazed on either juniper-infested (JIR) or juniper-free (JFR) rangelands until their kids were weaned at about 75 days of age. Fecal samples were analyzed with fecal near-IR spectroscopy to determine the percent juniper in the diet. Fecal samples were collected from does on JIR when their offspring were 30 days of age and at weaning. Then, does that raised kids in both rearing environments grazed a common JIR pasture for a 28-day adaptation period before collecting fecal samples. After weaning, kids from both rearing environments grazed JIR for 22 days before collecting fecal samples. The J+ does always consumed more (P < 0.001) juniper than J- does, demonstrating different maternal role models for kids reared in the JIR environment. There was no effect of rearing environment (P = 0.488) or rearing environment × selection line interaction (P = 0.096) when J- and J+ does grazed a common JIR pasture. The percentage of juniper in J- kid diets (7%) was the same regardless of the rearing environment. However, the rearing environment did affect the percentage of juniper in the diet of J+ kids, resulting in a gene-environment interaction (P = 0.022). The percentage of juniper in the diet of J+ kids reared in JFR (16%) and JIR (24%) were about two and three times higher than J- kids, respectively, indicating that genetics and the rearing environment contributed about equally to the increase in the percentage of juniper in the J+ kid diets. Regardless of the rearing environment, the J+ kids had a higher percentage of juniper in their diets than J- kids (P < 0.001). Compared to males, female kids had a higher percentage of juniper in their diets (12 vs 17%, respectively; P = 0.002). The ability to select animals with specific dietary preferences holds promise for targeted grazing strategies to restore degraded rangelands, with potential applications in conservation and ecosystem management.

Regression Models for In Vivo Discrimination of the Iberian Pig Feeding Regime after Near Infrared Spectroscopy Analysis of Faeces.

The Iberian pig is a native breed of the Iberian Peninsula, which holds an international reputation due to the superior quality and the added value of its products. Different rearing practices and feeding regimes are regulated, resulting in different labelling schemes. However, there is no official analytical methodology that is standardised for certification purposes in the sector. Near Infrared Spectroscopy (NIRS) is a technology that provides information about the physicochemical composition of a sample, with several advantages that have enabled its implementation in different fields. Although it has already been successfully used for the analysis of Iberian pig's final products, samples evaluated with NIRS technology are characterised by a postmortem collection. The goal of this study was to evaluate the potential of NIRS analysis of faeces for in vivo discrimination of the Iberian pig feeding regime, using the spectral information per se for the development of modified partial least squares regressions. Faecal samples were used due to their easy collection, especially in extensive systems where pig handling is difficult. A total of 166 individual samples were collected from 12 farms, where the three different feeding regimes available in the sector were ensured. Although slight differences were detected depending on the chemometric approach, the best models obtained a classification success and a prediction accuracy of over 94% for feeding regime discrimination. The results are considered very satisfactory and suggest NIRS analysis of faeces as a promising approach for the in vivo discrimination of the Iberian pigs' diet, and its implementation during field inspections, a significative achievement for the sector.

Assessment of in vitro digestibility and post-digestion peptide release of mare milk in relation to different management systems and lactation stages.

Mare milk has a unique protein composition that makes it a preferred option for adult and infant nutrition. Several functional properties have been attributed to this milk but with little evidence yet. In fact, knowledge on mare milk composition is still limited. In particular, studies addressing the performance of mare milk proteins during human gastrointestinal digestion are scarce, which limits the understanding of mare milk nutritional quality and functionality. For this reason, the present study describes the digestibility of mare milk proteins and the release of peptides as affected by management and lactation stage, factors known to affect milk composition. Mare milk samples from 3 different farms, and collected during 6 mo of lactation (n = 54), were subjected to a static in vitro gastrointestinal model to measure peptide release and protein digestibility. In the present study, a detailed description of protein and individual amino acid behavior during the digestion process was given. For the first time, digestion of the 2 equine ß-lactoglobulin isoforms (I and II) was described individually. In addition, it was found that lactation stage and management system can significantly affect protein digestibility and peptide release during gastrointestinal digestion of mare milk. Presumably, differences in the composition of mare milk influence the protein structure and enzyme accessibility, which might have an impact on digestion behavior. Despite no specific bioactive peptides were identified, several precursors of previously described bioactive peptides were found. These findings could support the idea of mare milk as a food with added value.

Reconstructing the reflectivity of liquid surfaces from grazing incidence X-ray off-specular scattering data.

The capillary wave model of a liquid surface predicts both the X-ray specular reflection and the diffuse scattering around it. A quantitative method is presented to obtain the X-ray reflectivity (XRR) from a liquid surface through the diffuse scattering data around the specular reflection measured using a grazing incidence X-ray off-specular scattering (GIXOS) geometry at a fixed horizontal offset angle with respect to the plane of incidence. With this approach the entire Qz -dependent reflectivity profile can be obtained at a single, fixed incident angle. This permits a much faster acquisition of the profile than with conventional reflectometry, where the incident angle must be scanned point by point to obtain a Qz -dependent profile. The XRR derived from the GIXOS-measured diffuse scattering, referred to in this paper as pseudo-reflectivity, provides a larger Qz range compared with the reflectivity measured by conventional reflectometry. Transforming the GIXOS-measured diffuse scattering profile to pseudo-XRR opens up the GIXOS method to widely available specular XRR analysis software tools. Here the GIXOS-derived pseudo-XRR is compared with the XRR measured by specular reflectometry from two simple vapor-liquid interfaces at different surface tension, and from a hexadecyltri-methyl-ammonium bromide monolayer on a water surface. For the simple liquids, excellent agreement (beyond 11 orders of magnitude in signal) is found between the two methods, supporting the approach of using GIXOS-measured diffuse scattering to derive reflectivities. Pseudo-XRR obtained at different horizontal offset angles with respect to the plane of incidence yields indistinguishable results, and this supports the robustness of the GIXOS-XRR approach. The pseudo-XRR method can be extended to soft thin films on a liquid surface, and criteria are established for the applicability of the approach.

Temporal-spatial variability of grazing behaviors of yaks and the drivers of their intake on the eastern Qinghai-Tibetan Plateau.

Introduction: Grassland-livestock balance is an important principle of sustainable development of grassland livestock production and grassland ecosystem health. Grassland degradation becomes more serious at global scales and especially at the area that is sensitive to climate change and human activities. Decreases in pasture biomass and shifts in plant community composition in degraded grasslands can largely affect grazing behaviors of livestock. Up to date, however, it is unclear that whether livestock behaviors change across spatial and temporal scales and what key factors are to shape observed behavioral patterns of livestock. Methods: Here, yak behaviors including grazing, rumination and walking on the eastern Qinghai-Tibetan Plateau (QTP) were monitored by a continuous visual observation, to investigate temporal and spatial variations of grazing behavior of yaks (Bos grunniens); based on the data from public database in the past 18 years, a meta-analysis was conducted to examine the main factors that affect grazing behaviors and intake of yaks. Results: We showed that grazing behaviors of yaks differed significantly within hours, among hours of each day and among days as well as across different observation sites. Intake rate of yaks was higher in the morning than in the afternoon, but walking speed showed an inverse trend compared with intake rate. Resting, altitude, the mean annual precipitation (MAP), the mean annual temperature (MAT), forage ash, yak age and season were the main predictors for yak intake, and forage and yak individual characteristics had direct effects on grazing behaviors and intake of yaks. Discussion: The findings confirm that grazing behaviors of yaks can vary even at small temporal scales and regional scales, which is closely related to the shift in forage quality and biomass caused by environmental changes. The study suggests that multiple factors can be responsible for the variation in livestock behaviors and shifts in behavioral patterns may consequently lead to positive or negative feedback to grassland ecosystems through plant-animal interactions.

Targeted grazing reduces a widespread wetland plant invader with minimal nutrient impacts, yet native community recovery is limited.

Targeted grazing to control undesirable plant species is increasingly of interest across a diversity of ecosystems, particularly as an alternative or complement to widely used herbicides. However, there are limited comprehensive evaluations of targeted grazing that evaluate both invasive species management effectiveness and potential negative effects on the ecosystem. Phragmites australis, a tall-statured, dense perennial invasive grass from Eurasia, is a pervasive problem in wetlands across the North American continent. As with many invasive species where management has historically relied on herbicides and resistance is a growing concern, land managers seek viable alternatives that have minimal negative ecosystem impacts. Grazing has been used for millennia to manage native Phragmites in Europe. Similarly, in its invasive range within North America, small-scale studies suggest Phragmites may be suppressed by grazers. Yet, the effectiveness of grazing at large scales and its effects on broader ecosystem properties remain largely unknown. We evaluated the influence of targeted grazing on vegetation, soil nutrients, and water nutrients over two years in large plots (∼300x the size of previous studies). We also tested the effects of mowing, a treatment that can be used to facilitate grazer access to large, dense Phragmites stands. In line with our predictions, we found that cattle grazing effectively suppressed invasive Phragmites over two years. Mowing reduced litter, and moderately reduced standing dead Phragmites, both of which suppress native plant germination in this system. However, these reductions in Phragmites were not accompanied by indications of native plant community recovery, as we had optimistically predicted. Despite the potential for grazing to reduce nutrient sequestration by plants and fertilize soils, we were surprised to find no clear negative effects of grazing on nutrient mobilization to groundwater or floodwater. Taken together, our findings indicate that targeted grazing, when implemented at broad scales over short time frames, is effective at achieving invasive plant management goals without sizable nutrient impacts. However, additional steps will be needed to achieve the restoration of diverse, robust native plant communities.

Investigating the effects of climate change and anthropogenic activities on SOC storage and cumulative CO2 emissions in forest soils across altitudinal gradients using the century model.

This study investigated the impact of climate change, grazing, manure application, and liming on soil organic carbon (SOC) stock and cumulative carbon dioxide (CO2) emissions in forest soils across different altitudes. Despite similar soil texture, acidity, and salinity across elevations, SOC stock significantly increased with altitude due to cooler temperatures and higher precipitation. The highest SOC stock (97.46 t ha-1) was observed at 2000-2500 m, compared to the lowest (44.23 t ha-1) at 500-1000 m. The Century C Model accurately predicted SOC stock, with correlation and determination coefficients exceeding 0.98. A climate change scenario projecting decreased precipitation (2.15 mm per decade) and increased temperature (0.4 °C) revealed potential SOC stock losses ranging from 28.36 to 36.35 %, particularly at higher altitudes. Grazing further decreased SOC stock, with a more pronounced effect at higher elevations. However, manure application (40 t ha-1 every four years) and liming (7-10 t ha-1 every three years) had positive effects on SOC stock, again amplified at higher altitudes and with an increase in lime application rate. In scenarios combining climate change with manure application and climate change with liming, manure application and liming mitigated some negative impacts of climate change, but could not fully offset them, resulting in 1.49-5.42 % and 0.39-4.07 % decreases respectively. Simulations of cumulative CO2 emissions mirrored the distribution of SOC stock, with higher emissions observed at higher altitudes and with management practices that increased SOC stock. This study emphasizes the critical role of conserving high-altitude forest soils and implementing optimal forest management strategies to combat climate change by minimizing SOC losses.

Three years of CO2, CH4 and N2O fluxes from different sheepfolds in a semiarid steppe region, China.

To better assess greenhouse gas (GHG) emissions from livestock folds in semi-arid steppe zones and reduce uncertainties in regional and national GHG emission inventories, we measured the fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from sheepfolds under contrasting management regimes (i.e., summer sheepfolds under continuous and rotational grazing strategies and the winter sheepfold) for 3 consecutive years. Our results showed that these GHG fluxes had high intra-annual and interannual variations, emphasizing the importance of multi-year measurement for achieving temporally representative annual budgets. Sheep presence and temperature appeared to be the key factors driving CH4, CO2 and N2O fluxes from sheepfolds, e.g., higher GHG emissions usually occurred in seasons with sheep presence. However, the sheepfold type exerted a distinct influence on the temperature sensitivity of GHG fluxes, i.e., the Q10 values for GHG fluxes were generally higher in summer sheepfolds than in winter sheepfold. The annual CH4, CO2 and N2O emissions for the 3 sheepfolds were estimated to be 1.5-16.5 kg C ha-1 yr-1 (or 1.9-2.6 g C yr-1sheep-1), 8.6-16.0 t C ha-1 yr-1 (or 5.1-6.6 kg C yr-1sheep-1) and 28.3-41.9 kg N ha-1 yr-1 (or 19.0-26.8 g N yr-1sheep-1), respectively. Averaging across the 3 years, the annual net GHG emissions (CH4 + CO2 + N2O) for all sheepfolds ranged from 47 to 71 t CO2-eq ha-1 yr-1 (or 27-36 kg CO2-eq yr-1 sheep-1), of which CO2 and N2O emissions contributed the most; moreover, the annual net GHG emissions had no significant differences between sheepfold types or grazing strategies. Given that local steppe soils have a lower magnitude of soil respiration (CO2) and N2O emissions and are also net sink for atmospheric CH4, the sheepfold sites in this region are undoubtedly one of the significant hotspots for GHG emissions and could be key areas to focus mitigation action.

Transcriptome and anatomical analysis of Stipa breviflora in response to different grazing intensities in desert steppe.

Stipa breviflora is a dominant species in the desert steppe of Northern China. Grazing is the main land use pattern of grassland, which could cause a variety of adaptive evolutionary mechanisms in plant community composition as well as individual plant growth and morphological characteristics. However, very little is known about the morphological structure and transcriptional regulation response to different grazing intensities in S. breviflora. In this study, transcriptome and anatomical analyses of S. breviflora under different grazing intensities, including no grazing, moderate grazing, and heavy grazing, were performed. The anatomical analysis results showed that epidermis cells and xylems significantly thicken with grazing intensity, suggesting that grazing results in increasing lignification. Furthermore, the components of cell walls such as lignin, cellulose, hemicellulose, and pectin were all increased dramatically and significantly under both moderate and heavy grazing. Transcriptome analysis showed that the differentially expressed genes related to different grazing intensities were also engaged in plant cell wall formation and in photosynthesis and respiration. In addition, the activities of ATP synthase and Rubisco-activating enzyme increased significantly with enhanced grazing intensity and differed significantly between moderate and heavy grazing intensities. The trends in transcriptome and plant phenotype changes are consistent. Taken together, these results indicated that S. breviflora has evolved a grazing tolerance strategy under long-term grazing conditions, influencing photosynthesis and respiration in terms of its own structure and enzyme activities in the body, to maintain normal life activities under different grazing conditions.

Strategic control of the cattle tick Rhipicephlaus microplus applied to rotational and silvopastoral grazing systems in subtropical areas.

This work evaluated if strategic control based on no more than three or four annual treatments is useful to control Rhipicephalus microplus infestations on cattle when it is applied to intensive rotational grazing and silvopastoral systems with high stocking rates in subtropical areas. In the intensive rotational grazing system, three annual treatments with chemical acaricides were applied on cattle in two different schemes: between spring and early summer and from late winter and late spring. Strategic control based on three treatments with chemical acaricides from late winter to late spring plus an additional fourth treatment in summer was tested in the silvopastoral system. In the intensive rotational grazing systems, the control schemes allow to reach a significant reduction in the tick load on cattle considering a time interval from spring to autumn. However, the efficacy levels were not high enough in some specific moments, namely, the tick counts of summer and autumn (there were not significant differences between treated and control groups). The scheme evaluated in the silvopastoral grazing system yielded better results than those tested for the intensive rotational system, because significant differences in tick load between treated and control groups were observed in all post-treatment counts and when the analysis was performed for the whole study period. However, values of efficacy in the count-by-count comparison were disparate, ranging from 64.1 to 99.7. Although the efficacy values obtained in the silvopastoral system were better than those of the rotational grazing systems, the total tick load on treated cattle in autumn was not low enough (mean abundance values 25.14 and 38.14). Ticks were more evenly distributed among hosts in late summer and autumn than in spring or early summer, where few hosts carry most of the ticks. Some management strategies as intensive rotational systems or silvopastoral structures can lead to a more efficient forage use, but they imply greater tick challenge than in extensive grazing systems. In these situations, the schemes of strategic control bases on three or four annual treatments should be complemented with additional tactical treatments in late summer or autumn.

Grazing affects ecosystem traits by regulating plateau pika activities at the landscape scale.

The mechanism underlying the effects of livestock grazing on grassland ecosystem traits has been greatly discussed. However, as a common small burrowing mammal on the Tibetan Plateau grasslands, the plateau pika's (Ochotona curzoniae) influence on alpine grassland ecosystem traits has rarely been investigated, especially beyond the plot scale. In this study, we flew an unmanned aerial vehicle (UAV) over a grassland landscape under grazing and nongrazing treatments. Mounted visible spectral remote sensing, in combination with field surveys, was utilized to explore how livestock and pika grazing modify grassland ecosystem traits at the landscape scale on the Tibetan Plateau (TP). Using object-oriented classification and partial least squares regression, we retrieved the pika burrow distribution and grassland ecosystem traits. Then, the relationships among livestock grazing, pika burrowing and ecosystem traits were evaluated. The results indicated that livestock grazing reduces the alpine meadow community height by 0.13 cm and the species number by 0.25 while increasing the vegetation coverage by 9.69 % and the aboveground biomass (AGB) by 10.07 g/m2. A lower statue grassland community with greater coverage caused by livestock grazing promotes pika burrowing. Pika burrow density increases 100/ha per 1.70 % increase in vegetation coverage, a 1.87 g/m2 increase in AGB or a 0.08 m decrease in community height. Under livestock grazing, both community structure and nutrients are more strongly associated with pika burrow density. The structural equation model demonstrated that livestock grazing regulates pika burrow density by moderating structural value and subsequently affecting nutritional value. Pika burrowing activity explains 40 % of the total variation in nutritional value. Our findings revealed an intrinsic linkage between mammal activities and alpine grassland ecosystems, which can provide guidelines for grassland management through pika population control by adjusting grazing intensity on the TP.

Grazing decreases net ecosystem carbon exchange by decreasing shrub and semi-shrub biomass in a desert steppe.

Livestock grazing can strongly determine how grasslands function and their role in the carbon cycle. However, how ecosystem carbon exchange responds to grazing and the underlying mechanisms remain unclear. We measured ecosystem carbon fluxes to explore the changes in carbon exchange and their driving mechanisms under different grazing intensities (CK, control; HG, heavy grazing; LG, light grazing; MG, moderate grazing) based on a 16-year long-term grazing experimental platform in a desert steppe. We found that grazing intensity influenced aboveground biomass during the peak growing season, primarily by decreasing shrubs and semi-shrubs and perennial forbs. Furthermore, grazing decreased net ecosystem carbon exchange by decreasing aboveground biomass, especially the functional group of shrubs and semi-shrubs. At the same time, we found that belowground biomass and soil ammonium nitrogen were the driving factors of soil respiration in grazed systems. Our study indicates that shrubs and semi-shrubs are important factors in regulating ecosystem carbon exchange under grazing disturbance in the desert steppe, whereas belowground biomass and soil available nitrogen are important factors regulating soil respiration under grazing disturbance in the desert steppe; this results provide deeper insights for understanding how grazing moderates the relationships between soil nutrients, plant biomass, and ecosystem CO2 exchange, which provide a theoretical basis for further grazing management.

Livestock turnover and dynamic livestock carrying capacity are crucial factors for alpine grassland management: The Qinghai-Tibetan plateau as a case study.

Alpine grasslands are distributed widely on high-elevated ranges and plateaus from the wet tropics to polar regions, accounting for approximately 3% of the world's land area. The Qinghai-Tibetan Plateau (QTP) is the highest and largest plateau in the world, and approximately 60% of the plateau consists of alpine grassland, which is used mainly for grazing animals. Livestock structure was determined in Guinan (GN), Yushu (YS) and Maqu counties (MQ) on the QTP by interviewing 235 local pastoralists. Based on data collected from GN, the livestock carrying capacity was calculated using herbage dry matter biomass intake (LCCm) by the livestock, and the metabolizable energy yield (LCCe) and digestible crude protein (LCCp) available in pasture. The pasture area per household differed among the regions of the QTP, which was the main reason for the difference in livestock stocking rate. The householders raised the appropriate proportion of breeding females and young yaks and sheep in GN and MQ, but not in YS, to maintain a constant turnover. Most pasture in YS was used at the community level, especially in summer. The calculated carrying capacities based on metabolizable energy yield (LCCe) of the pasture and dry matter biomass (LCCm) were similar in most months except for August, when the value of LCCe was higher than LCCm. Based on the digestible protein of the pasture, the calculated livestock carrying capacity overestimated the actual carrying capacity during the herbage growing season from May to September. Appropriate practices should be taken in different regions of QTP, such as providing supplementary feed, especially protein, during the forage non-growing season. Livestock carrying capacity should be adjusted dynamically, and calculated by a number of parameters. The stocking rate should be controlled to optimize livestock production and curb or minimize grassland degradation to generate a sustainable system. This study examined the grasslands and LCC on the QTP, but the results could be applied to grasslands worldwide.