High Grazing Research Articles

A Global Synthesis of the Effects of Livestock Activity on Hydrological Processes

The livestock sector supports billions of people worldwide, yet when poorly managed, can have substantial negative effects on soils and ecosystem functions. Despite numerous studies and reviews of the effects of livestock activity on hydrological functions, a global synthesis of their effects on different biotic (vegetation, herbivore type) and abiotic (climate, soil, spatial scales) factors remains elusive. This makes it difficult to provide ecologically based advice on how best to manage grazing to minimise environmental damage and maximise hydrological functions. We used a global meta-analysis to examine the effects of livestock activity on hydrological inflows (infiltration, soil moisture), and outflows (runoff, sediment) using a dataset compiled from 3044 contrasts of grazed and ungrazed data from 129 publications between 1935 and 2020. Overall, we found that livestock activity increased sediment production (+ 52 ± 19.8%; mean ± 95% CI), reduced infiltration (− 25 ± 5.2%), but had no significant effect on either runoff (+ 27 ± 29.6%) or soil moisture (− 5 ± 5.9%). These impacts varied markedly among herbivore types and intensity, with greatest reductions in infiltration at high and low grazing contrasts, and more pronounced negative effects of grazing when sheep and cattle grazed together than either alone. The impact of livestock activity also varied with climatic region, soil texture, and the interaction between aridity and plant cover. Our study demonstrates the nuanced effects of livestock activity, with herbivore type and intensity, and environmental context modifying the hydrological outcomes. Livestock grazing is unlikely to result in positive environmental outcomes for infiltration and sediment production.

Sheep grazing impacts on soil methanotrophs and their activity in typical steppe in the Loess Plateau China

Soil methanotrophs are the only biological sink for atmospheric methane (CH4). The activity and the diversity of methanotrophic communities in grassland soils can be impacted by animal grazing. In this study, soils were collected from a 17-year running grazing intensity trial in a typical steppe in the Loess Plateau, China to examine the responses of CH4 oxidation rate and active methanotroph composition and abundance to different levels of sheep grazing. Soils were collected from summer grazed pastures at no (0 sheep ha−1), low (2.67 sheep ha−1), moderate (5.33 sheep ha−1) and high (8.67 sheep ha−1) levels of grazing. We found that all soils were able to oxidize atmospheric and high concentration (10%) CH4 through soil methanotrophs. Compared to ungrazed soils, the atmospheric CH4 oxidation rate and methanotroph abundance were higher in low and high grazed soils but lower in moderately grazed soils. Across all soils, the in-situ methanotroph community was dominated by upland soil cluster gamma methanotrophs and potentially contributed to the atmospheric concentration CH4 oxidation. Soil methanotroph community responses to the high 13CH4 concentration revealed an increase in methanotroph abundance and a transition of the active methanotroph community to traditional Type I (Methylocaldum and Methylobacter) and Type II (Methylocystis) methanotrophs. Methylocaldum responses to the high CH4 concentration were greater in highly grazed soil than in ungrazed soil. The activity of Methylobacter and Methylocystis under high CH4 concentrations was reduced by high grazing intensity. This study provides evidence that recent intensifications of animal grazing can result in particular community assembly of microbial methane oxidizers responsible for CH4 sink capabilities of grassland soils.

Additional floristic study of planktonic and seaweed-associated diatoms in Chuuk, Micronesia

AbstractThe present study enhances knowledge of the biodiversity of diatoms in Chuuk, Micronesia following our 2018 study on the seaweed-associated diatoms. We collected planktonic samples of diatoms from five sites of reef flats using a 20 μm mesh net, and two samples of seaweeds with epiphytes by hand from an islet on the barrier reef. In addition, the seaweed-associated diatoms from our 2018 study were analysed using scanning electron microscopy. A total of 109 diatom taxa are documented in the present study. Of these, 70 species were from net samples, and 39 species from the seaweed-associated diatoms. Thirty-one species are newly recorded from Micronesian waters. Most taxa are benthic or tychoplanktonic; euplanktonic diatoms were rare. The occurrence of benthic diatoms from the water column might be related to the Chuuk environmental conditions which include shallow water, strong light intensity and high grazing pressure, to which benthic diatoms seem to be able to better adapt than planktonic diatoms.

Browsing herbivores improve the state and functioning of savannas: A model assessment of alternative land-use strategies.

Changing climatic conditions and unsustainable land use are major threats to savannas worldwide. Historically, many African savannas were used intensively for livestock grazing, which contributed to widespread patterns of bush encroachment across savanna systems. To reverse bush encroachment, it has been proposed to change the cattle‐dominated land use to one dominated by comparatively specialized browsers and usually native herbivores. However, the consequences for ecosystem properties and processes remain largely unclear. We used the ecohydrological, spatially explicit model EcoHyD to assess the impacts of two contrasting, herbivore land‐use strategies on a Namibian savanna: grazer‐ versus browser‐dominated herbivore communities. We varied the densities of grazers and browsers and determined the resulting composition and diversity of the plant community, total vegetation cover, soil moisture, and water use by plants. Our results showed that plant types that are less palatable to herbivores were best adapted to grazing or browsing animals in all simulated densities. Also, plant types that had a competitive advantage under limited water availability were among the dominant ones irrespective of land‐use scenario. Overall, the results were in line with our expectations: under high grazer densities, we found heavy bush encroachment and the loss of the perennial grass matrix. Importantly, regardless of the density of browsers, grass cover and plant functional diversity were significantly higher in browsing scenarios. Browsing herbivores increased grass cover, and the higher total cover in turn improved water uptake by plants overall. We concluded that, in contrast to grazing‐dominated land‐use strategies, land‐use strategies dominated by browsing herbivores, even at high herbivore densities, sustain diverse vegetation communities with high cover of perennial grasses, resulting in lower erosion risk and bolstering ecosystem services.

Relative Impact of Climate Change and Grazing on NDVI Changes in Grassland in the Mt. Qomolangma Nature Reserve and Adjacent Regions during 2000–2018

As the roof of the world, the Mt. Qomolangma National Nature Reserve and adjacent regions have a fragile environment and are very sensitive to global climate change. Based on the MODIS and SPOT remote sensing data during 2000–2018, we aimed to explore the change trend and driving factors of grassland in this area under the dual influence of climate change and human activities. Here, temperature and precipitation data were enrolled as the main indicators of climate change, while the number of livestock at the end of the year was regarded as the key indicator of grazing. The results showed that: (1) during 2000–2018, the grassland NDVI reflected an overall increasing trend, and the impact of precipitation was more significant than those of temperature and grazing at both pixel and county levels; (2) probably due to the large population and high grazing intensity, the grassland NDVI in Tingri County was controlled by both precipitation and grazing. In general, precipitation exerts a greater impact on the NDVI changes since this region is characterized by arid and semiarid climates. In some areas, vegetation growth is simultaneously affected by both grazing and climate factors due to the relatively greater pressure of grazing. In the context of future warming, control of the number of tourists for Mt. Qomolangma, as well as that of livestock in Tingri County, will help improve sustainability development and to reduce the adverse effects of grassland degradation.

Positive effects of low grazing intensity on East African bee assemblages mediated by increases in floral resources

Livestock grazing is widespread and increasing in the African grasslands, with largely unknown consequences for bee pollinators. Here we assessed the direct and indirect impacts of livestock grazing intensity on bee assemblages in East African grasslands and tested if the effect of grazing intensity on bee assemblages depends on temperature. We collected data on 24 study sites representing three different levels of livestock grazing intensity in northern Tanzania. Ordinary linear models and path analysis were used to test the effect of grazing and temperature on floral resources and bee diversity. Non-metric multidimensional scaling (NMDS) and permutational MANOVA were used to analyze changes in bee community composition and bee-visited plant community with grazing intensity and temperature. We found that moderate livestock grazing slightly increased bee species richness while high grazing intensity led to a strong decline. Further, bee species richness was highest at moderate temperatures and significantly lower in colder and very hot environments. Path analysis results showed that the effect of livestock grazing and environmental temperature on bee species richness is mediated by a positive effect of moderate grazing on floral resource richness. Livestock grazing led to a significant change in the species composition of bee communities, this effect was stronger in environments with very high temperatures. Our study reveals that bee communities of the African savannah zone may benefit from low levels of livestock grazing as this proliferates the growth of flowering plant species. However, livestock grazing at high intensity will cause significant species losses and turnover of bee species communities; effects which may increase with climatic warming.

Analysis of Technical, Allocative and Economic Efficiencies of Vitamin A Cassava Farmers with Other Improved Cassava Farmers in Benue State, Nigeria.

Purpose: Despite that cassava is important economically and nutritionally, a gap exists between its demand and supply. Consequently, analysis of technical, allocative and economic efficiencies of Vitamin A Cassava (VAC) farmers with other improved cassava (OIC) farmers in Benue State, Nigeria was conducted.
 Methodology: A five- stage sampling technique was employed to select 120 farmers in the study area. Primary data were obtained using structured questionnaire and interview methods to seek information on socio-economic characteristics of farmers, inputs, outputs, and constraints to cassava production. The data were analyzed using descriptive statistics, stochastic frontier production function and cost function.
 Findings: The result revealed that profitability alone is not the only determinant for cassava cultivation, other factors were adequate finance, farmland, planting material, labour, nutrition and market. Five major determinants of cassava production were farm size, family labour, stem, herbicide and hired labour. Education, farming experience, gender and extension contacts significantly influenced farm -specific profit inefficiencies. OIC farmers showed higher allocative efficiency (0.78) than VAC farmers (0.75) and lower economic mean efficiency (0.66) than VAC farmers (0.76). The VAC farms were more profitable than OIC farms with gross margin of ₦181,120 and ₦105,620 per hectare of land, return on investment (1.68 and 0.86). The mean efficiencies of both practices were significant(p<05). The OIC and VAC farmers were operating at the second level of production frontier with return to scale of less than unity (0.457 and 0.448). Constraints identified are inadequate finance, expensive stems, inadequate extension agents’ visit, low market demand, high labour cost and grazing of farmland by herders.
 Unique contribution to theory, practice, and policy: Vitamin A Cassava and other improved cassava were smallholder farmers who were technologically inspired to transform inputs into output to earn income, food for households and poverty alleviation, and to achieve these, they need to improve on technical, allocative and economic efficiencies of production. It is recommended that cassava farmers develop saving culture and enter contract farming, multiply cassava stems, employ labour-saving technologies, government to create ready markets and encourage herders to establish ranches to prevent incursion of roaming cattle herds into farms.

Disturbance Induced Changes in Diversity of Medicinal Plants in a Dry Tropical Forest of India

Due to overexploitation for forest resources, many important medicinal plants are disappearing from the tropical dry forest (TDF) regions. The present study is aimed to investigate the diversity of medicinal plants exposed to different levels of anthropogenic disturbance in TDFs. For this study, we selected six forest regions, covering a radius of 25 km, and exposed to variable intensity of disturbances, in the form of illegal logging, cattle grazing and fire. Based on the intensity of three disturbances, we categorized the study sites as low (LDS) and high (HDS) disturbed sites, and analyzed differences in soil properties and vegetation parameters in the two disturbance categories. We recorded tree density, tree species richness and herbaceous species richness in 100 m2 quadrats at the selected regions. Results exhibited significantly greater soil organic C (LDS, 4.6%; HDS, 0.9%; P < 0.001), water holding capacity (LDS, 47.4%; HDS, 33.6%; P < 0.001), and sand content (LDS, 53.7%; HDS, 48.3%; P < 0.001) across LDS, whereas significantly higher bulk density (LDS, 1.30 gcm–3; HDS, 1.34 gcm–3; P < 0.05) and gravel content (LDS, 14.6%; HDS, 20.0%; P < 0.001) across HDS. We found considerable shift in relationships between vegetation parameters under the two disturbance regimes. The results indicated that many of the important medicinal plants (e.g., Adina cordifolia, Bauhinia vahlii, Holarrhena antidysenterica, Asparagus racemosus, Curculigo orchioides, Hemidesmus indicus, etc.) which are potential constituents of several ayurvedic preparations as well as of traditional medical systems are lacking from the HDS, either due to direct impact of disturbances or indirectly due to disturbance induced changes in soil properties. For instance, the high grazing pressure increased soil compaction, leading to increase in bulk density and decline in water holding capacity of soil. We suggest that forest managers take into consideration the presence of anthropogenic disturbances in their management and conservation efforts of medicinal plants in TDFs.

Effect of Grazing Exclusion and Rotational Grazing on Soil Aggregate Stability in Typical Grasslands in Inner Mongolia, China

Soil aggregate is extremely important for soil health and sustainable land management. Overgrazing has caused serious degeneration of grassland in the past decades and how to restore the degraded soil through grazing management is urgently needed. In this research, we investigated effects of long-term grazing exclusion and short-term rotational grazing with different grazing intensities on aggregate stability in the upper 10 cm of soil at two grazing sites in Xilinhot, Inner Mongolia. Treatments included long-term (34 years) exclusion, moderate-term (21 years) exclusion, and continuous grazing at adjacent reference plots. In addition, effects of rotational grazing under different grazing intensity [i.e., no grazing (0 days/month), light grazing (3 days/month), moderate grazing (6 days/month) and high grazing (12 days/month)] were investigated after 5 years. Stability of aggregate fractions were determined using wet sieving. Our results showed that the stable aggregates fraction were significantly increased under grazing exclusion for both fine (0.25–1 mm) and coarse (1–2 mm) size fractions. At the rotational grazing site, stability of fine aggregates was significantly enhanced under grazing compared with no grazing, while there was little influence on stability of coarse aggregates. Our results showed that grazing exclusion significantly increased soil aggregate stability and the peak appeared in moderate-term exclusion, meanwhile, rotational grazing had little influence on aggregate stability. We suggest that rotational grazing rather than long-term grazing exclusion is a better way for soil aggregate stability and soil health, and current grazing prohibition policies may need to be adjusted.

Excessive livestock grazing overrides the positive effects of trees on infiltration capacity and modifies preferential flow in dry miombo woodlands

AbstractThe increase in livestock grazing in African drylands such as miombo woodlands threatens land productivity and ecosystem functioning. Trees have positive effects on soil hydraulic properties, but few studies have looked at grazing intensity and hydrological functioning in different land uses. Therefore, we conducted a biophysical survey in Morogoro Rural District, Tanzania, where we identified four main land uses and land cover types, that is, Forest reserve, open‐access forest, cropland under fallow, and active cropland. We assessed grazing intensity, measured infiltration capacity, and conducted dye tracer experiments to assess the degree of preferential flow in 64 plots. We also tested the effect of grazing exclusion on infiltration capacity in 12‐year‐old fenced plots. Our results show that irrespective of land use or cover type, soil bulk density increased by 10% from low to high grazing intensity, whereas infiltration capacity and soil organic carbon decreased by 55% and 28%, respectively. We found a positive relationship between infiltration capacity and tree basal area in plots with lowest grazing intensities. However, at higher grazing, the infiltration capacity remained low independently of the basal area. Preferential flow in deeper soils was six‐times higher in areas with no grazing, indicating higher deep soil and groundwater recharge potential at low grazing intensities. We conclude that the negative impacts on soil hydrological functioning of excessive livestock grazing override the positive effect of trees, but restricting grazing can reverse the impact.

Linking and Sharing Technology: Partnerships for Data Innovations for Management of Agricultural Big Data

Combining data into a centralized, searchable, and linked platform will provide a data exploration platform to agricultural stakeholders and researchers for better agricultural decision making, thus fully utilizing existing data and preventing redundant research. Such a data repository requires readiness to share data, knowledge, and skillsets and working with Big Data infrastructures. With the adoption of new technologies and increased data collection, agricultural workforces need to update their knowledge, skills, and abilities. The partnerships for data innovation (PDI) effort integrates agricultural data by efficiently capturing them from field, lab, and greenhouse studies using a variety of sensors, tools, and apps and provides a quick visualization and summary of statistics for real-time decision making. This paper aims to evaluate and provide examples of case studies currently using PDI and use its long-term continental US database (18 locations and 24 years) to test the cover crop and grazing effects on soil organic carbon (SOC) storage. The results show that legume and rye (Secale cereale L.) cover crops increased SOC storage by 36% and 50%, respectively, compared with oat (Avena sativa L.) and rye mixtures and low and high grazing intensities improving the upper SOC by 69–72% compared with a medium grazing intensity. This was likely due to legumes providing a more favorable substrate for SOC formation and high grazing intensity systems having continuous manure deposition. Overall, PDI can be used to democratize data regionally and nationally and therefore can address large-scale research questions aimed at addressing agricultural grand challenges.

Environmental Conditions and Grazing Exerted Effects on Arbuscular Mycorrhizal in Plants at Southern Patagonia Rangelands

Arbuscular mycorrhizal (AM) fungi play a major role in maintaining ecosystem functions. AM fungi are found in most ecosystems including rangelands currently under increasing pressures from human activities. Southern Patagonia (Argentina) is a semiarid region influenced by extensive livestock production in rangelands. There is a lack of information about the environmental conditions and functionality of AM fungi in plant species of Patagonia ecosystems associated with livestock grazing. We assessed how soil properties, climatic conditions, and grazing intensities influence the response of AM fungi colonization. We studied most palatable and representative plant species (Poa dusenii, Rytidosperma virescens, Festuca gracillima, Nardophylum bryoides, Mulguraea tridens, and Carex argentina) growing in main ecological areas of Southern Patagonia. Most of the studied plant species (except C. argentina) presented AM symbiosis. AM colonization showed a negative relationship with soil organic carbon and nitrogen and a positive relationship with soil bulk density and pH. Results suggest that plants promoted a higher root AM colonization when soil nutrients and water availability (rainfall) are limiting. Sheep stocking rates had a differential impact depending on the ecological areas and plant life forms. High grazing decreased the AM colonization in the ecological areas with palatable plant dominance, suggesting that the impacts of grazing could lead to further negative effects on the ecosystem. Moderate grazing allows to maintain higher AM colonization, which would probably benefit the aboveground production of palatable plant and, consequently, to herbivores, particularly in degraded rangelands like Patagonian steppes. This study improves the knowledge of AM association in Patagonian semiarid rangelands by increasing our understanding of the impacts of grazing on belowground ecology. This information becomes relevant for grazing sustainable management, which may contribute to food security.

Comments on “Spatial Utilization and Microhabitat Selection of the Snow Leopard (Panthera uncia) under Different Livestock Grazing Intensities”

Abstract Large expanses of snow leopard habitat overlap with extensively used areas for livestock grazing. A fundamental question for conservationists is to determine whether livestock production can be reconciled with the conservation of rare and threatened large carnivores. Therefore, numerous studies focus on the relationship between carnivore densities and space use and environmental, anthropogenic, and topographic variables. Using snow leopard sign surveys in areas with high and low grazing disturbance, Hong et al. posit that livestock grazing directly impacts fine-scale habitat selection by snow leopards. The authors recommend controlling livestock grazing to help restore habitat complexity and alpine environment diversity. However, the approach by which Hong et al. have reached this conclusion is inadequate and is based on a methodology that fails to address the research question appropriately. We argue that 1) identification of a biologically relevant scale of study is the first essential step toward inferring carnivore–habitat relationships, 2) the authors draw inconsistent conclusions from their data on sign densities in high and low grazing disturbance areas, 3) ideally, the snow leopard–livestock relationship needs to be examined across a gradient of livestock grazing intensities and at multiple spatial scales, and 4) it is inappropriate to draw conclusions for landscape/regional scales from a study conducted at a finer and undefined scale. We suggest that future studies should clearly define the scale of the study, identify appropriate habitat variables of interest, and use meaningful measurement instruments to serve as proxies for variables of interest.

Decision support tools for grass-based fodder management on Walloon dairy farms: current adoption and perspectives

Description of the subject. Many decision support tools (DSTs) have been developed to help dairy farmers optimally manage the high variability in the quality and availability of grass-based fodder, but their adoption rate remains low. Objectives. The objective was to characterize and understand the adoption rate of DSTs related to using grass-based fodder. Methodology. A sample of 61 Walloon (Belgium) dairy farmers responded to an online survey concerning their current use of 23 DSTs related to using grass-based fodder either directly (pasture or grassland) or indirectly (feeding or techno-economic), as well as barriers to and incentives for adopting them, their current interest in DSTs, and satisfaction with the guidance on using these DSTs. Results. Pasture management DSTs were used the least, even though farmers were the most interested in them. Farmers used simple indicators rather than software or automated tools. Farmers indicated that DSTs were too expensive and time consuming, even if they could ultimately save them time and money. Continuing education is lacking. Four types of users were identified who influence the use of DSTs: high user no grazing (H-NG), high user traditional or technical grazing (H-T/TG), low user traditional grazing (L-TG), and moderate user organic (M-ORG). Conclusions. Communicating with end-users during each step of DST development would help (1) identify the specific needs of a diverse set of dairy farmers and (2) develop DSTs that better correspond to their practices. More long-term guidance is required to inform farmers about existing DSTs and to transfer the knowledge required to use them.

Veränderungen der Laufkäferzönose auf einer Wasserbüffelweide im NSG „Freiburger Rieselfeld“

Ground beetles were studied in 2018 and 2020 in a water buffalo pasture of just under 5 ha established in 2018 in the nature reserve „Freiburger Rieselfeld”. In each of the two years there were four trap series and five trapping periods. A total of 75 species were detected, including six species that are endangered at federal and/or state level, three vulnerable species and eight near threatened species. Of particular note were the detections of Harpalus cupreus in both years and Syntomus obscuroguttatus in the second survey year, for which only very few records of occurrences exist. Between 2018 and 2020, specialized wetland species within the pasture declined as a result of the dry-hot years, while the populations of characteristic species of dry-warm open habitats increased. As a result of thinning of the woody stands within the pasture, typical forest species declined. The most significant declines, however, were in specialized seed predators, which no longer found grass seeds in the area due to the relatively high grazing intensity.

短期牦牛放牧强度对川西北高原高寒草甸土壤细菌群落的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 短期牦牛放牧强度对川西北高原高寒草甸土壤细菌群落的影响 DOI: 10.5846/stxb202011273042 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（42001055）；中央引导地方-自由探索项目（20ZYZYTS0020）；西南民族大学中央高校基本科研业务费专项（2020NQN27）和研究生创新型科研项目（CX2020SZ22） Effects of short-term yak grazing intensity on soil bacterial communities in an alpine meadow of the Northwest Sichuan Plateau Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:气候变化和人类干扰使青藏高原的草地退化日趋严重，特别是过度放牧导致的草地退化现象尤为突出；然而，牦牛作为青藏高原分布广且数量多的重要家畜，其不同放牧强度对高寒草甸土壤理化性质与细菌群落的影响仍不明晰。在川西北高原典型高寒草甸开展牦牛放牧强度试验，设置了对照组（禁牧）、轻度放牧（1头牦牛/hm2）、中度放牧（2头牦牛/hm2）和重度放牧（3头牦牛/hm2）4个放牧强度，每个强度设置3个重复。两年放牧实验后的结果表明：短期的重度放牧导致土壤有效磷显著增加，而其它土壤性质在各放牧强度变化不显著；随着放牧强度的增加，土壤细菌α多样性呈先增加后减少的趋势，其主要原因是牦牛活动为细菌的生长繁殖提供了有利的营养条件，但由于放牧的持续时间较短，变化不显著；就优势菌而言，土壤绿弯菌门中存在光合自养细菌，在重度放牧下显著高于对照组，其它各菌门在不同放牧强度下无显著差异；土壤氮与硝化螺旋菌门呈正相关，速效磷与酸杆菌门也呈显著正相关，均说明放牧强度对土壤细菌类群的影响是通过土壤性质间接实现的。本实验通过研究不同牦牛放牧强度下的土壤细菌群落结构，为放牧策略的制定提供了基础数据支持，为草地退化的防治提供理论依据。 Abstract:As an important part of China, the Qinghai-Tibetan Plateau plays a vital role in the balance of global ecosystems. Climate change and human activities have led to grassland degradation on the Qinghai-Tibetan Plateau, especially overgrazing-induced grassland degradation. However, as one of the most dominated livestock on the Qinghai-Tibetan Plateau, the effects of different yak grazing intensities on soil physicochemical properties and microbial communities and structures still remain unclear. To address yak grazing effect on soil bacterial communities, we conducted a yak grazing intensity experiment in a typical alpine meadow of the Northwest Sichuan Plateau. According to local investigations and previous experiment, we set four grazing intensities, including control group (no grazing), light grazing (1 yak/hm2), moderate grazing (2 yak/hm2), and heavy grazing (3 yak/hm2). After two years of grazing experiments, we found that heavy grazing significantly increased soil available phosphorus and short term grazing reduced the bulk density in the 0-10cm soils, while other soil properties showed no responses to different grazing intensities. The possible reason may be that the effect of grazing on soil physicochemical properties was long-term, and the short-term grazing intensity of yak was difficult to change soil properties. The α diversity of soil bacteria increased firstly and then decreased with the increasing grazing intensity, but the changes were not statistically significant due to the short duration of grazing experiment. On the one hand, yak grazing could provide available nutrients for the growth of bacteria through dung and urine. On the other hand, high grazing intensity changed the root distribution and root exudates of plants, and increased ultraviolet radiation reduced the diversity of bacteria. In terms of the dominant bacteria, the Chloroflexi was significantly higher under no-grazing than that under heavy grazing, which has photosynthetic autotrophic bacteria. In contrast, other phylum had no significant differences among grazing intensities. With the increase of grazing intensity, the relative abundance of Actinobacteri and Firmicutes increased firstly and then decreased, while Acidobacteria and Gemmatimonadetes showed reverse trends. The β diversity of soil bacteria showed that grazing intensity had no significant effect on bacterial community structure. Soil total nitrogen is positively correlated with Nitrospira. There was a significantly negative correlation between soil total phosphorus and Acidobacteria, but soil available phosphorus was also significantly positive related to Acidobacteria, indicating that grazing intensity indirectly affect soil bacteria may be through changing soil properties. This study provides basic data to grazing managements and a theoretical basis to the restoration of degraded grasslands. 参考文献 相似文献 引证文献

Overutilization of Pastures by Livestock

Soil degradation caused by overgrazing is a worldwide problem. The degradation of an overutilized area occurs mainly where animals prefer to spend extra time because of the attractants that are around gateways, water sources, along fences or farm buildings. High grazing pressure decreases plant density which results in changes of the botanical composition of a pasture. The effect that grazing has on a plant depends on the timing, frequency and intensity of grazing and its opportunity to regrow. Overgrazing adversely effects soil properties, which results in reduced infiltration, accelerated runoff and soil erosion. Evidence has been corroborated with high bulk density values, high dry mechanical resistance and low structural stability. The degradation of the landscape may be a short-term phenomenon and recovery is possible after grazing pressures have been greatly reduced. Management practices have been used successfully to improve grazing distribution. These practices include water development, placement of salt and supplements, fertilizer application, fencing, burning, and the planting of special forages which can be used to enhance grazing by livestock in underutilized areas.The authors carried out their grazing experiment on the Hortobágy. The effects of overutilization by livestock on soil properties and vegetation on certain areas of grassland are presented in this paper.

Initial soil conditions outweigh management in a cool-season dairy farm's carbon sequestration potential

Pastures and rangelands are a dominant portion of global agricultural land and have the potential to sequester carbon (C) in soils, mitigating climate change. Management intensive grazing (MIG), or high density grazing with rotations through paddocks with long rest periods, has been highlighted as a method of enhancing soil C in pastures by increasing forage production. However, few studies have examined the soil C storage potential of pastures under MIG in the northeastern United States, where the dairy industry comprises a large portion of agricultural use and the regional agricultural economy. Here we present a 12-year study conducted in this region using a combination of field data and the denitrification and decomposition (DNDCv9.5) model to analyze changes in soil C and nitrogen (N) over time, and the climate impacts as they relate to soil carbon dioxide (CO2) and nitrous oxide (N2O) fluxes. Field measurements showed: (1) increases in soil C in grazed fields under MIG (P = 0.03) with no significant increase in hayed fields (P = 0.55); and (2) that the change in soil C was negatively correlated to initial soil C content (P = 0.006). Modeled simulations also showed fields that started with relatively less soil C had significant gains in C over the course of the study, with no significant change in fields with higher initial levels of soil C. Sensitivity analyses showed the physiochemical status of soils (i.e., soil C and clay content) had greater influence over C storage than the intensity of grazing. More extensive grazing methods showed very little change in soil C storage or CO2 and N2O fluxes with modeled continuous grazing trending towards declines in soil C. Our study highlights the importance of considering both initial system conditions as well as management when analyzing the potential for long-term soil C storage.

Benefits of Short-Duration, High-Stocking Rate Opportunistic Grazing on Arid Rangelands During Favorable Conditions

The aim of this study was to assess the impact of short grazing periods with high-stocking density on vegetation during weather conditions favorable to plant growth. Continuous grazing is widely practiced in Tunisian arid rangelands and across most drylands and deserts of the Middle East and North Africa. In the early 1990s, the Tunisian government combined a variety of incentives and restrictions on rangeland grazing practices and initiated a national strategy for rangeland improvement. The strategy emphasizes grazing exclusion for three consecutive years, a practice known locally as gdel. At the end of this period, grazing is allowed with no restrictions or with some guidelines. However, these regulations created discontent among pastoral communities, mainly when local rainfall conditions result in a considerable quantity of green biomass. High stocking-density grazing for a short period would help satisfy pastoralist concerns and achieve the government’s strategic goal. This study was implemented in three arid rangeland types of southern Tunisia that have been under restricted grazing for 2 years. Each area in the study was grazed for short periods in late May (about 7 days) with a flock of 150 head of sheep. Measurements of vegetation cover, forage productivity, density, and species richness were taken before and after grazing. Our results suggest that perennial vegetation is more stable under grazing than annual vegetation. The presence of annual species would enhance rangeland vegetation cover and diversity and at the same time offers an opportunity for livestock to select a high-quality diet rich in protein. Opportunistic grazing, applied to heterogeneous rangelands in late spring and the beginning of the annual temperature increase, encouraged animals to select annual plants due to their higher palatability, higher digestibility, and water content rather than heavily grazing perennial species. Perennial biomass materials that die and do not fall through rapid biological decay tended to decline with increased period of placement, resulting in further oxidation to CO2 which affects photosynthetic performance negatively and may eventually cause plant death. Trampling from high-density stocking enhances the litterfall rates and removes the oxidized plant material. These findings may contribute to strategies for addressing the extreme climatic variations that threaten rangeland and livestock sustainability.

Grazing influences biomass production and protein content of alpine meadows

Alpine grasslands are essential for carbon sequestration and food supply for domestic and wild herbivores inhabiting mountainous areas worldwide. These biomes, however, are alternatively threatened by the abandonment of agricultural and livestock practices leading to a fast-growing shrubification process while other mountain grasslands are suffering from the impacts of overgrazing. The functioning of alpine meadow ecosystems is primarily driven by climatic conditions, land-use legacies and grazing. However, although it is critically important, the role of large herbivores on the aboveground biomass and protein content of palatable plants is poorly understood for most alpine meadows. In this work, we explore the effects of grazing on grassland vegetation at two different spatial and temporal scales in the Eastern Pyrenees, Spain. Remote sensing was used to assess the effect of high and moderate grazing (HG and MG respectively) on grass biomass using the leaf area index (LAI) at the meso-scale (patches between 2.3 and 38.7 ha). We also explored the impact of null (NG), overgrazing (MO, mimicked overgrazing) and high (HG) grazing intensities at local scale setting eighteen 1 m2 exclusion boxes in six meadows (three boxes each) commonly used by domestic and wild ungulates. Historical satellite data showed that LAI values are greater in high than in low grazed areas (HG, mean = 0.66, LG, mean = 0.55). Along the same lines, high and moderate grazing pressures improved biomass production at the local-scale (HG, mean = 590.3 g/m2, MO, mean = 389.3 g/m2 and NG, mean = 110.8 g/m2). Crude protein content reached higher values under MO pressure than under HG pressure. Our results confirm that grazing intensity exerts significant changes on the above-ground biomass production and the protein content of plants consumed by domestic (cattle and horses) and wild ungulates (Southern Chamois, Rupicapra pyrenaica). We can conclude that ungulates sustain biomass and nutritive values of grass exerting a negligible effect on biomass and protein content of woody vegetation. Our results will inform management guidelines to support profitable grazing activities and promote conservation of the open landscapes in the alpine ecosystems under the current global change scenario.