Grazing Exclusion Research Articles

The quality and quantity of SOM determines the mineralization of recently added labile C and priming of native SOM in grazed grasslands

Continuous and pulsed inputs of labile organic carbon (LOC) into soil are common. However, because soil microbial responses to LOC input are rapid, the relative contributions of respiration derived from LOC to total microbial respiration and their influencing factors remain elusive. Furthermore, although numerous studies have explored the priming effect (PE) of soil organic matter (SOM) mineralization induced by LOC addition, few studies have focused on its short-term effects. There are some indications that the response of soil microbes to LOC input depends on the microbial demand of nutrients, especially C and N. Therefore, variations in soil C and N characteristics may further influence microbial response processes to LOC inputs and the decomposition of LOC and SOM, but a comprehensive understanding of this is lacking. To address this gap, 13C-labeled glucose was added to six temperate grassland soils with different C/N ratios (9.98–12.0), which were collected from areas with different grazing exclusion durations and at different soil depths. The microbial respiration was measured at 9-min intervals across a 105-h period. We found that soil microbes responded rapidly to LOC input, and microbial biomass controlled by soil organic C (SOC) and C/N was the most important factor directly influencing the intensity of the microbial response to LOC input. Grazing and deeper soil layers decreased the respiration derived from LOC and their relative contribution to total respiration, mainly attributed to variations in soil C/N and fungal/bacterial ratio (Fu/Ba). LOC addition stimulated SOM decomposition in all soils and increased respiration of SOM by 11.3–92.4 mg C/g SOC, equivalent to 18.7–266.1 % priming. Grazing and increased soil depth resulted in a greater PE and soil C loss, with soil C/N and SOC content being the most important regulators. Overall, this study revealed the important influence of LOC on soil C fluxes and highlighted the important role of SOM quality and quantity in regulating grassland soil C cycling.

Responses of Vegetation, Soil, and Microbes and Carbon and Nitrogen Pools to Semiarid Grassland Land-Use Patterns in Duolun, Inner Mongolia, China

Previous studies have observed that increased precipitation positively affects primary production in semiarid grasslands in Inner Mongolia, while soil carbon (C) and nitrogen (N) strongly influence how ecosystems respond to precipitation as well as anthropogenic disturbances under different management strategies. Therefore, in this study, we investigated the storage of organic C and N in four grassland sites with similar flora and landforms but with different grazing intensities to characterize how the storage and concentrations of C and N respond to relief from grazing pressure and precipitation. The concentrations of soil organic carbon (SOC), soil total nitrogen (STN), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN), as well as the contents of soil bacteria and fungi in the 0–50 cm soil layers, were measured. The results showed that SOC, STN, MBC, and MBN storage varied greatly among the four grassland sites (p < 0.05), with all decreasing significantly with grassland degradation and increasing greatly with the exclusion of grazing, i.e., the establishment of natural grassland (NG). More than 90% of C and 95% of N stored in the soil were lost due to heavy grazing, but the losses were smaller in other nutrient pools (including the aboveground biomass, litter, and roots). Interestingly, the proportion of the particle size fractions (clay, silt, and sand) had a stronger effect on limiting the soil and microbial nutrient pools compared to precipitation. The limited range of C and N storage found in these grassland soils indicated that enclosed fencing was a valuable management tool with a high potential to sequester C in the top meter of the soil, showing a stronger effect than precipitation. This study provides a theoretical basis for improving grassland recovery in semiarid areas that have been heavily grazed.

Effects of grazing exclusion on vegetation community characteristics over 22 years in the Zoige alpine meadows from China

The grazing exclusion is a core policy implement applied by governments to rehabilitate degraded grasslands in China. However, the effects of grazing exclusion on species diversity, interspecific association, and niche overlap values changes in the Zoige alpine meadows are still unclear. The purpose of the paper aims to answer the following questions: (1) How do species diversity, interspecific association, and niche overlap values changes in grazed sites with time? (2) When is the optimal exclusion in the Zoige alpine meadows? Based on the method of space-for-time substitution, we investigated the amount of plant species in seven grazing exclusions established separately in 1996, 2007, 2009, 2011, 2012, 2016, and 2017 (representing seven succession stages of 22, 11, 9, 7, 6, 2, and 1 years after grazing exclusion, respectively), compared with free grazing. Aboveground plant biomass remarkably increased with time under short-term fencing, but no differences were found under long-term fencing. As for underground plant biomass, it obviously increased with time under short-term fencing, but significantly decrease under long-term fencing. Moreover, plant species richness firstly decreased and then increased with time under short-term fencing, while it significantly decrease under long-term fencing. The analysis of variance test showed that all species pairs in short-term fencing have a positive correlation, while negative correlation in long-term fencing. The niche breadth values of total species ranged from 0 to 0.75. These results indicated that short-term fencing for less than two years is beneficial to vegetation recovery in the Zoige alpine meadows.

Linking ecosystem service benefit and grazing prohibition intensity can better optimize fence layout in northern Tibet

AbstractThere is an urgent need to link grazing exclusion policy and the resulting benefits for fence layout management. However, policy implementation intensity and benefits are rarely considered together. Here, combining the changes in the rate of the livestock and fenced area, we constructed a grazing prohibition intensity (GPI) index that reflected the intensity of policy implementation. We also quantified ecosystem service benefits (ESBs), including net primary productivity (NPP) and soil conservation by the different models. Then, a new perspective in combination with ESBs and GPI was used to assess whether a fence layout is appropriate using the four–quadrant model and how to optimize a potentially unreasonable fence layout based on seven drivers. We found that the NPP and soil conservation service notably increased by 59% and 87%, respectively, in the total fenced area, after the implementation of the grazing exclusion program. The high values of ESBs and GPI were concentrated in the eastern and central‐eastern regions of the northern Tibet, respectively. Moreover, the potentially unreasonable fence layout accounted for 10% of the total fenced area, and was focused on meadow areas with a high human footprint. The area proportion of reasonable fence layout coupling ESBs and GPI increased by 20% compared with ESBs individually. Finally, an optimal potential unreasonable fence layout might reduce the mismatch between the ESB and GPI by considering countermeasures such as attention to the potential unreasonable fence layout, setting a target for supplying carbon sinks and soil and water conservation quantities and reducing the human footprint. Our study indicates the necessity of linking ESBs and GPI for fence layout management.

Influence of grazing on the activity pattern and temporal niche of two dominant rodent species in Alxa desert

Grazing by large herbivores can potentially affect interspecific interactions between small herbivores by reducing the ecological fitness of animals. Desert rodents are important components in desert ecosystems and indicators of environmental change. Grazing reduces food resources, but rodents can decrease interspecific niche overlap by adaptive behavior. However, the key factors driving rodent behavioral activities and coexistence in the Alxa desert remains unstudied. We monitored population density and behavioral activities of Midday gerbil (Meriones meridianus) and northern three-toed jerboa (Dipus sagitta) in a grazing exclusion experiment in Alxa desert, Inner Mongolia, China, in 2017. We assessed the relationship between environmental factors (such as plant height, density, coverage, rainfall and temperature) and the behavioral activities of two coexisting rodent species. The results showed that: (1) In summer, grazing significantly reduced the activity time of gerbil and jerboa compared to that in grazing exclusion areas (gerbil: F = 5.98, p < 0.05, η2 = 0.22; jerboa: F = 8.57, p < 0.01, η2 = 0.28). Grazing reduced the temporal niche overlap with an obvious shifting of activity peaks between two species. (2) Grazing exclusion enhanced the temporal niche overlap between the two rodent species due to greater food availability which relieved inter-specific competition in each season. (3) Grazing strengthened the sensitivity of rodents to environmental changes in all seasons. These results indicated that grazing affected competition between the rodent species by altering vegetation conditions, which in turn affected the temporal niche and activity patterns of rodents.

物种多样性和功能性状驱动高寒草原地上生物量对长期禁牧的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 物种多样性和功能性状驱动高寒草原地上生物量对长期禁牧的响应 DOI: 10.5846/stxb202203070549 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院战略性先导科技专项(A类)(XDA26020201-2);青海省自然科学基金项目(2019-ZJ-910) Diversity of species and functional traits drive jointly responses of aboveground biomass to long-term grazing exclusion at alpine steppe 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:围封对草地生物多样性和初级生产力的影响是草地生态学研究的热点问题之一。基于2013-2021年在青藏高原东北部紫花针茅(Stipa purpurea)高寒草原围栏内外植物群落长期调查数据,从物种多样性、功能性状的角度解析了高寒草原地上生物量对长期围封的生态响应过程。结果表明:(1) 围封处理对高寒草原物种多样性的负效应具有强烈的时间依赖性。围封处理显著提高地上生物量,但也显著降低了生物量稳定性和异步性,意味着高寒草原稳定的、可持续的生态系统服务功能被长期围封处理削弱。(2) 植物功能性状对长期围封处理表现出差异性响应模式;与叶绿素性状相比,叶形态性状对长期围封处理表现出更强的敏感性。(3) 物种多样性和功能性状与地上生物量之间均存在显著相关关系,并且物种多样性的影响被功能性状调控进而对地上生物量发挥间接效应,群落加权性状和功能分异度共同对草地生物量发挥直接的主导效应。研究结果证明了植物功能性状通过介导物种多样性与其共同驱动高寒草原地上生物量对长期围封的响应。因此,在未来草地管理过程中,同步研究植物物种和功能属性对于全面揭示生态系统的响应机制至关重要。 Abstract:Responses of biodiversity and productivity at grassland to fencing have been a hotspot in grassland ecology for a long period. In this study, long-term field investigation along inside and outside of the fence at Stipa purpurea alpine steppe in northeastern of the Qinghai-Tibetan Plateau from 2013 to 2021 was used to elucidate ecological responses processes of aboveground biomass of alpine steppe to long-term fencing from perspectives of species diversity and plant functional traits. The main results showed as follows: (1) the negative effects of fencing treatment on species diversity presented strong time-dependence, and the aboveground biomass increased but both stability and asynchrony of biomass decreased after experiencing long-term fencing, suggesting that potential of stable and sustainable provision of eco-services were eroded by the fencing treatment; (2) Responses of plant functional traits to long period fencing were different. Specifically, the sensitivity to the fencing was stronger in morphological trait than that in chlorophyll traits; (3) The significant relationships between the biomass and species, functional traits diversity were also detected, and effects of species diversity regulated by functional traits played indirect roles to aboveground biomass, specially community-weighted traits and functional divergence index jointly played directly dominant effects on biomass. The study demonstrates that plant functional traits through mediating species diversity drive jointly responses of aboveground biomass to long-term grazing exclusion at alpine steppe. Therefore, evaluating the plant species and functional trait factors simultaneously would be all-important for revealing comprehensively ecosystem responses to environmental perturbations at grassland managements in the future. 参考文献 相似文献 引证文献

Short-Term Effect of Grazing Exclusion and Uncontrolled Grazing on Species Abundance, Dry Matter Yield and Nutritive Value in an Invaded Area by <i>Euryops floribundus</i> in the Eastern Cape, South Africa

Short-Term Effect of Grazing Exclusion and Uncontrolled Grazing on Species Abundance, Dry Matter Yield and Nutritive Value in an Invaded Area by <i>Euryops floribundus</i> in the Eastern Cape, South Africa

Response of soil microbial compositional and functional heterogeneity to grazing exclusion in alpine shrub and meadows in the Qinghai-Tibet Plateau.

Soil microorganisms found in shrub-meadow ecosystems are highly heterogeneous and extremely sensitive to grazing, but changes in microbial compositional and functional heterogeneity during grazing exclusion (GE) have been largely overlooked compared to community diversity. We collected soil samples from heavily grazed plots (6.0 sheep/ha) and GE plots (matrix and patch areas in both), and used a combination of next-generation sequencing, vegetation features, and the associated soil property data to investigate the effect of GE on the composition and function of microbial communities (bacteria fungi, and archaea) in 0-10 cm soils. Regarding community composition, the proportions of species in bacteria, fungi, and archaea were 97.3, 2.3, and 0.4%, respectively. GE significantly affected the species diversity of fungi and archaea but not that of bacteria. GE decreased the heterogeneity of bacteria (2.9% in matrix and 6.2% in patch) and archaea (31.1% in matrix and 19.7% in patch) but increased that of fungi by 1.4% in patch. Regarding community function, enzyme diversity and heterogeneity were increased by 10.4 and 9.4%, respectively, in patch after 6 years of fencing, exemplifying a high level of microbial functional redundancy. The Kyoto Encyclopedia of Genes and Genome pathways-cell growth and death, translation, digestive system, and nucleotide metabolism-were functional biomarkers (linear discriminant analysis effect size method) in matrix-non-grazed plots, whereas lipid metabolism, xenobiotics biodegradation and metabolism, and metabolism of terpenoids and polyketides, cell motility, cancer: overview, endocrine system, and membrane transport were biomarkers in patch-non-grazed plots. Additionally, GE improved the capacity for fatty acid metabolism but decreased the abundance of methane-producing archaea by 42.9%. Redundancy analysis revealed that the factors that affected microbial composition the most were soil aggregates, soil moisture, and the number of plant species, whereas those that affected microbial function the most were soil available phosphorus, soil temperature, and shrub canopy diameter. Our results quantified soil microbial heterogeneity, emphasizing the different responses of the composition and function of bacteria, fungi, and archaea to GE in alpine shrubs and meadows.

Effects of a decade of grazing exclusion on three Wyoming big sagebrush community types

Livestock grazing is the most extensive land use in Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis [Beetle & A. Young] S.L. Welsh) steppe and its effects on plant community characteristics have been greatly debated. However, most of the studies used to support grazing removal evaluated the impacts of excluding historic grazing, rather than the impacts of excluding moderate contemporary grazing (40–50% utilization, altering season of use) which has vastly different effects on plant communities. Thus, to understand the effects of removing contemporary grazing, we compared contemporary grazed areas to long-term (+10 yrs.) grazing exclusion areas in three common Wyoming big sagebrush community types: intact, degraded, and exotic annual grass-dominated types. Plant community characteristics (cover, density, diversity, richness, dissimilarity) were measured in 2020 and 2021 in five grazed and grazing excluded areas within each community type. Most plant community characteristics were not influenced by grazing exclusion, suggesting that the removal of contemporary grazing has little effect on Wyoming big sagebrush plant communities. The effect of grazing exclusion on Sandberg bluegrass (Poa secunda J. Presl) abundance and litter cover varied among community types, suggesting that grazing exclusion effects slightly varied among community types. In contrast, most plant community characteristics varied among community types and between years, suggesting that grazing management plans need to account for the spatial and temporal variability among Wyoming big sagebrush communities. Furthermore, our results suggest that contemporary grazing exclusion has negligible effects compared to contemporary grazing on plant communities, and that exclusion of contemporary grazing (passive restoration) does not promote the recovery of degraded and annual grass invaded plant communities.

Long-term grazing exclusion affects the population genetics and functional traits of Artemisia frigida in Mongolia

Steppes have a long history of grazing, which has affected vegetation and ecosystem functioning to varying degrees depending on local environmental and climatic conditions. While the effects of grazing on plant species' diversity and composition are well documented, effects on plants' functional traits and genetic structures are far less widely studied. Similarly, the effects of climate/land-use interactions on plants’ functional traits or genetic structure have rarely been investigated.We conducted a study on the largest representative example of the Palearctic steppe biome, in Mongolia, using long-term grazing exclusion along a broad climatic gradient. We investigated the influence of grazing on the population genetics and functional traits of the prominent shrub species Artemisia frigida. A total of 187 individuals were sampled from eight locations along the Trans-Mongolian Railway and in the Hustai National Park. Comparisons were made between enclosed (ungrazed) and open (grazed) sites and analyzed using ten microsatellite loci.Grazing had a significant positive effect on genetic diversity but no effect on population genetic differentiation. Climatic and soil variables strongly influenced population genetic structure, with soil nutrient availability being positively associated with genetic diversity. Grazing significantly influenced functional traits (plant height, specific leaf area), however, no relationship was found between genetic diversity and plant functional traits. Overall, given that ungrazed A. frigida populations showed lower genetic diversity, a moderate level of grazing is likely to be beneficial for the species, which may also help stabilize ecosystem functioning in steppes more broadly.

Responses of carbon dynamics to grazing exclusion in natural alpine grassland ecosystems on the QingZang Plateau.

In the context of "Carbon Emissions Peak" and "Carbon Neutrality", grazing exclusion (GE) has been applied widely to rehabilitate degraded grasslands and increase carbon sequestration. However, on the QingZang Plateau (QZP), the impacts of GE on the carbon dynamics of alpine grasslands are poorly understood, particularly at a regional scale. To fill this knowledge gap, we evaluated the responses of carbon sequestration to GE in different alpine grasslands across QZP by using meta-analysis. The effects of GE on ecosystem carbon fractions were dependent on GE duration, grassland types and climate factors. Specifically, our results indicated that GE had more obviously positive effects on carbon stock across the alpine meadow than the alpine steppe. However, when considering different GE duration, the longer duration of GE was more effective for increasing ecosystem carbon sequestration (R 2 = 0.52, P<0.0001) in the alpine steppe. Our results further demonstrated that annual mean precipitation (AMP) and temperature (AMT) began to dominate ecosystem carbon sequestration after three years of GE duration across the alpine meadow; and AMP was an important climate factor limiting ecosystem carbon sequestration (R 2 = 0.34, P<0.01) in the alpine steppe. In terms of plant carbon fraction, GE generated continuous positive effect (P<0.05) on aboveground biomass with the increased GE duration in the alpine meadow, while this positive effect disappeared after the 8th year of GE duration. And no positive effects were found on belowground biomass in the 11th year in alpine steppe. For soil organic carbon (SOC), there existed periodic fluctuations (increased and then decreased) on SOC in response to GE. For microbial biomass carbon, there were no obvious trends in response to GE duration. In general, we highlighted that the responses of different carbon fractions (plant-soil-microbe) to GE were non-uniform at spatial and temporal scales, thereby we should adopt different carbon management practices for sustainable development of different grasslands.

How Seasonal Grazing Exclusion Affects Grassland Productivity and Plant Community Diversity

The Sanjiang Plain is famous for its concentrated distribution of natural wet grasslands. These wet grasslands are an important source of seasonal pasture or hay in the area. However, changes in community structure and ecosystem function have already occurred in wet grasslands because of overgrazing and climate change, resulting in severe grassland degradation. Exploring a reasonable grazing management strategy is crucial for improving grassland species diversity, increasing grassland productivity, and maintaining sustainable grassland utilization. We investigated the effects of five grazing management (GM) strategies (no grazing through the growing season (CK), spring grazing exclusion (Spr-GE), summer grazing exclusion (Sum-GE)), autumn grazing exclusion (Aut-GE), and grazing through the growing season (G)) on the productivity, community composition and structure of wet grasslands in the Sanjiang Plain under three grazing intensities (GI) (light (L), moderate (M), and heavy (H)). Results showed that Spr-GE and Sum-GE were beneficial in increasing total aboveground biomass (AGB), but decreased plant community diversity in Spr-GE due to increased intraspecies and interspecies competition. The exclusion of different seasonal grazings changed the composition of plant communities. At the level of functional groups and dominant species, Spr-GE had a significant effect on most functional groups and dominant species’ characteristics, while Aut-GE had little effect on most functional groups and dominant species’ characteristics. However, different functional groups and dominant species had different responses to seasonal grazing exclusion. In addition, under M, there were significantly improved grassland total AGB and PF AGB. The results indicated that Spr-GE with M may be an effective livestock-management strategy to protect grassland vegetation and community diversity, as well as to restore degraded grassland.

Grazing and light modify Silene latifolia responses to nutrients and future climate

Altered climate, nutrient enrichment and changes in grazing patterns are important environmental and biotic changes in temperate grassland systems. Singly and in concert these factors can influence plant performance and traits, with consequences for species competitive ability, and thus for species coexistence, community composition and diversity. However, we lack experimental tests of the mechanisms, such as competition for light, driving plant performance and traits under nutrient enrichment, grazer exclusion and future climate. We used transplants of Silene latifolia, a widespread grassland forb in Europe, to study plant responses to interactions among climate, nutrients, grazing and light. We recorded transplant biomass, height, specific leaf area (SLA) and foliar carbon to nitrogen ratio (C:N) in full-factorial combinations of future climate treatment, fertilization, grazer exclusion and light addition via LED-lamps. Future climate and fertilization together increased transplant height but only in unlighted plots. Light addition increased SLA in ambient climate, and decreased C:N in unfertilized plots. Further, transplants had higher biomass in future climatic conditions when protected from grazers. In general, grazing had a strong negative effect on all measured variables regardless of added nutrients and light. Our results show that competition for light may lead to taller individuals and interacts with climate and nutrients to affect traits related to resource-use. Furthermore, our study suggests grazing may counteract the benefits of future climate on the biomass of species such as Silene latifolia. Consequently, grazers and light may be important modulators of individual plant performance and traits under nutrient enrichment and future climatic conditions.

Effect of grazing exclusion on emission of greenhouse gases and soil organic carbon turnover in alpine shrub meadow

Grazing exclusion (GE) is a management option used widely to restore degraded grassland and improve grassland ecosystems. However, the impacts of GE on soil properties and greenhouse gas emissions of alpine shrub meadow are still unclear, especially long-term GE of more than ten years. To fill part of this gap, we examined the effects of long-term GE of alpine shrub meadow on soil nutrients, soil properties, greenhouse gas emissions (CO2 and CH4) and soil organic carbon (SOC) turnover. When compared to grazed grassland (GG), long-term GE resulted in: 1) greater SOC, nitrogen (N), and phosphorous (P) content, especially in the 20–30 cm soil layer; 2) greater soil C:N, C:P and N:P ratios in the 20–30 cm depth; 3) greater soil CO2, but lesser CH4 emission during the growing season; and 4) much faster SOC turnover time (0–30 cm). GE of more than ten years can increase grassland C reserves and improve the C sequestration capacity of the ecosystem. Results from this study can have important implications in developing future grassland management policies on soil nutrient balances, restoration of degraded grassland and controlling shrub expansion.

Changes in Richness and Species Composition after Five Years of Grazing Exclusion in an Endemic Pasture of Northern Mexico

A well-managed grazing system improves the productivity and health, and it is important to promote sustainability. We analyzed the impact of grazing on the Sierra de Zapalinamé protected area in north Mexico. Our hypothesis was that grazing modifies species composition, richness, and nutrients after grazing exclusion for five years. In this area, eight plots were excluded from grazing, and species richness, evenness, and plant functional types for five years were monitored. This monitoring was also carried out on eight control plots adjacent to the excluded plots. Soil samples were collected from each plot in the fifth year of exclusion for nutrient content analysis. Grazing discriminated plant species composition after five years between excluded and control plots, but not species richness and evenness. In addition, exclusion increased grass cover and decreased forb cover. Indicator species for excluded and control sites were identified. It was concluded that part of the pastures can be excluded from grazing as a way to analyze changes in this protected area and promote greater plant diversity.

Effects of fencing on near-term ecosystem multifunctionality in a typical steppe in Inner Mongolia

Fencing has been extensively used for the restoration of grassland degraded by human disturbance. However, its effects on ecosystem functions and services are still controversial. Here, we evaluated the response of ecosystem multifunctionality (EMF) to 7 years of grazing exclusion based on ten individual functions, and compared grazing exclusion with two common practices (mowing and grazing) in a typical steppe in Inner Mongolia. Plant and microbial diversity and three edaphic factors (soil pH, moisture and temperature) were also investigated to explore the main drivers regulating EMF. Compared with continuous grazing, fencing improved EMF mainly by increasing soil nutrient contents, including soil organic carbon, ammonium nitrogen, nitrate nitrogen and available phosphorus. No significant differences were found between fencing and mowing for all ten individual functions and EMF. Plant and fungal diversity were comparable between fencing and grazing, but were lower than under mowing, and bacterial diversity was similar between all three management practices. Soil pH, moisture and temperature were also affected by fencing. Structural equation modeling showed that EMF was mainly driven by soil moisture in the fencing and mowing plots, but by plant and bacterial diversity in the grazing plots. Our results suggest that relative to grazing, fencing and mowing are both feasible strategies to enhance EMF, and that mowing may be more conducive to biodiversity conservation. This study demonstrates that, maintenance of soil moisture is critical for the restoration of EMF in Inner Mongolia’s typical steppe.

Differences in arthropod communities between grazed areas and grazing exclosures depend on arthropod groups and vegetation types

Livestock grazing is one of the most common management practices for grasslands and can greatly affect their biodiversity. However, arthropod diversity response patterns to grazing regimes are difficult to predict. We conducted a short-term grazing exclusion experiment in traditionally managed alkali grasslands in Hungary to investigate differences between grazed and ungrazed vegetation for different arthropod groups. The experiment was laid out in a full factorial design, with twelve 50 × 100 m short-term grazing exclosures in vegetation types with high (alkali wet meadow) and low productivity (alkali steppe). We sampled ground beetles and spiders with pitfall traps and true hoppers by sweep netting. We used vegetation type (wet meadow vs dry steppe), management (grazed vs ungrazed) and their interaction as fixed effects in mixed models. We found higher species richness and activity density of spiders and ground beetles in the more productive wet meadow vegetation, where the community structure of each arthropod group also shifted toward hygrophilous species. Significant interactions between vegetation type and management indicated a dependence of management effects on vegetation types: arthropod community structure shifted towards hygrophilous species in ungrazed meadows, but not in ungrazed steppe sites. True hopper abundance was higher in grazed meadow sites, but lower in grazed steppe sites, compared to ungrazed sites. True hopper community structure shifted toward generalist herbivores in ungrazed sites, regardless of vegetation type. We concluded that vegetation types determine arthropod communities and modulate the effects of grazing on arthropods. Our results suggest that moderate disturbance from low-intensity grazing has a positive or neutral effect in wetter, more productive vegetation, but a negative or neutral effect in drier, less productive vegetation, depending on the arthropod group. Herbivorous insects that dwell on plants are particularly affected by management because they are more susceptible to direct impacts, such as unintentional predation by grazing cattle, and because of asymmetrical competition between mammalian and insect herbivores.

Distributions of medium mineral elements with long-term grazing exclusion in a semi-arid grassland of Inner Mongolia

• F18 and F39 altered distributions of medium mineral elements in plant and soil. • F18 and F39 shifted medium mineral elements from root to other parts. • Ca, Mg, and Si were shifted from soil to plant at F39 than F18. • Ca was shifted from root to litter at F39 than F18. • Mg, S, and Si were shifted from litter to root or green plant at F39 than F18. The variations of medium mineral elements in long-term grazing exclusion grassland have been few studied. Therefore, the contents, stocks, and proportions of calcium (Ca), magnesium (Mg), sulphur (S), and silicon (Si) in green plant-litter-root-soil continuum were evaluated by grazing exclusion for 18-, and 39-year (F18 and F39) and continue grazing (F0) in Mongolia grassland. Results showed that F18 and F39 decreased the stocks of Mg and Si in green plant and the stocks of Ca and Mg in 20–50 cm root ( p < 0.05). F18 and F39 increased the stocks of S in 0–100 cm soil and the stocks of elements in litter ( p < 0.05). Compared to F18, F39 increased the stocks of elements in 0–20 cm root, especially Si ( p < 0.05), and a 30.3 % higher of Ca stock in green plant was observed ( p < 0.05). The stock of Ca and Mg in 0–100 cm soil at F39 was 164.3 % and 72.6 % lower than that at F18, respectively ( p < 0.05). F39 decreased the stocks of Mg, S, and Si in incomplete- and complete decomposed litter relative to F18. We concluded that four elements were shifted from root to other parts with long-term grazing exclusion. However, Ca, Mg, and Si were shifted from soil to plant with grazing exclusion for 39 years relative to 18 years, and Ca was shifted from root to litter, and Mg, S, and Si were shifted from litter to root or green plant.

Changes in climate, grazing pressure and nutrient inputs affect the structural integrity and functioning of Andean shrublands

ABSTRACT Background Changes in climate and the intensity of agriculture expansion can alter plant population dynamics and community composition and structure of dry shrublands. Aims We tested how temperature and moisture along an elevation gradient, grazing, and nutrient addition in soil affected demographic attributes of Croton shrubs and the composition and structure of plant species in an inter-Andean dry shrubland. Methods At three elevations, we installed grazing and exclusion plots, combined with four nutrient treatments: control, and addition of nitrogen (N), phosphorous (P) alone and in combination. We measured recruitment and survival of Croton seedlings, as well as survival, growth, fruiting of adult Croton and the composition and structure of neighbouring plants. Results Grazing exclusion improved adult survival of Croton at all three elevations. Grazing exclusion and addition of N and P increased adult growth of Croton at low and medium elevations. Croton seedling recruitment and survival decreased with distance to adult plants. The cover of Croton had a positive relationship with plant abundance and diversity. Conclusions Temperature, moisture, grazing and nutrient addition can alter the demography and cover of Croton, as well as the composition and structure of its neighbouring plants threatening the functioning of the inter-Andean dry shrubland.

Grazing exclusion altered the pattern of the soil seed bank but not the aboveground vegetation along an altitudinal gradient in alpine grassland

AbstractGrazing exclusion by fencing is the principal option to restore degraded grassland, but its effects on recovery and succession of vegetation are not clear, especially in high mountain areas. In this study, we aimed to fill this gap by assessing the effect of seven‐year grazing exclusion on vegetation and soil seed bank along an altitudinal gradient in northern Tibet, China. Species richness, Shannon‐Wiener index and Simpson's diversity index of vegetation and soil seed bank, seed density, and the Sørensen index all displayed a mid‐domain (hump‐shaped) pattern with increasing altitude, except for the Shannon‐Wiener and Pielou indices of soil seed bank in fenced grasslands. These results demonstrated that the impact of grazing exclusion on the patterns of vegetation and soil seed bank change with altitude but are not synchronous. Grazing exclusion increased vegetation coverage but decreased soil seed bank density, and species diversity of vegetation and soil seed bank. The Sørensen index (0.03–0.2) and non‐metric multidimensional scaling (NMDS) analysis indicated that the species composition differed between vegetation and soil seed bank, but no difference was found between fenced and grazed grasslands. The low similarity suggests that the soil seed bank contributes little to vegetation recovery in alpine grassland. Seven‐year grazing exclusion had no effect on either vegetation succession or species composition of soil seed bank in alpine grassland. Overall, our findings suggest reconsidering the use of long‐term grazing exclusion to restore degraded grassland at high altitudes (above 4400 m above sea level) on the Tibetan Plateau.