Grazed Plots Research Articles

Seasonal Grazing Does Not Significantly Alter the Particle Structure and Pore Characteristics of Grassland Soil

Seasonal grazing is a recognized and sustainable approach to livestock management, but there is still a lack of comprehensive research on its impact on soil structure. This study utilizes advanced scanning electron microscopy technology to quantitatively evaluate the long-term effects of seasonal grazing on grassland soil structure, focusing on soil pore distribution characteristics and particle size. The investigation offers a detailed visual representation of the arrangement of soil particles at a micro-level. In both grazed and ungrazed plots (NG), soil particles ranging from 0.005 to 0.05 mm and 0.075 to 0.25 mm in size were predominant, constituting 20% and 60%, respectively. In plots subjected to seasonal grazing (grazing in June and August, G68, and grazing in July and September, G79), micro-particles (0.002–0.005 mm) and particles sized 0.05–0.075 mm were significantly lower compared to NG. Scanning electron microscope (SEM) images demonstrate structural differences, with NG displaying a higher proportion of small to medium-sized particles, more small pores, and fewer large pores. Analysis of pore size and morphology reveals the prevalence of large pores in both grazed and ungrazed plots. Continuous grazing plots exhibit significantly higher proportions of large pores compared to NG, while seasonal grazing plots show no significant differences. Correlation analyses indicate associations between soil physicochemical properties, particle size, and pore structure. Total soil nitrogen (TN), total soil carbon (TC), and soil moisture positively correlate with 0.005–0.05 mm particle proportions, while EC is negatively correlated with 0.05–0.075 mm particles. This study enhances our understanding of the effects of grazing practices on soil structure and provides scientific evidence for sustainable land management.

92 Rearing system influenced the performance, GI-parasite burden, and immune profile of pregnant does during winter

Abstract Small ruminants in the Southeast are predominantly raised outdoors, regardless of seasons and associated weather conditions. Severe weather in winter can decline the performance of pregnant animals and compromise their performance and immunological states. Indoor raising of pregnant animals during winter may minimize the adverse effect of cold stress; however, such potential has not been evaluated. This study hypothesized that performance, GI-parasite burden, and immune response would differ between pregnant does raised outdoor and indoor during winter. The objective of this study was to evaluate the performance, GI-parasite burden, and hematological, biochemical, and immunological parameters of pregnant does raised outdoor and indoor in winter. The study was conducted from late January to early April 2023. Sixteen pregnant Kiko does were divided into outdoor and indoor groups. Outdoor group was kept in one grazing plot consisting of mobile shelters, mineral feeders, hay feeders, and watering troughs. Indoor group was kept in individual pens consisting of containers for water, minerals, hay, and grain. Both groups were given corn and soybean mixed in 3:2 ratio (0.8% of animal body weight), ad libitum hay, minerals, and water. Daily ambient temperature and relative humidity (RH) data were collected for both sites, and temperature-humidity index (THI) was calculated. Animal performance data [body weight, body condition score (BCS), and FAMACHA score] and fecal samples were collected on d 1, weekly during the study, and at the end of the study. Fecal samples were analyzed for the type and quantity of GI parasites using the McMaster technique, and parasite eggs per gram of animal feces (EPG) was calculated. Blood samples were collected on d 1, 34, and 69 and analyzed for hematological, biochemical, and immunological parameters. Data on weather, animal performance, and hematological, biochemical, and immunological parameters were analyzed using the GLM procedure and EPG data were analyzed using the Wilcoxon Rank-Sum test in SAS 9.4. Indoor temperature was higher (7%, P < 0.01), RH was lower (8%, P < 0.05), and THI was higher (5%, P < 0.01) vs. outdoor. Overall, indoor does had better FAMACHA by 9% (P < 0.05) and greater EPG by 35% (P < 0.05). Eosinophils were reduced by 73% (P < 0.05), calcium was increased by 11% (P < 0.01), and total bilirubin was greater by 86% (P < 0.05) in indoor does at the end of the study (P < 0.05) vs. outdoor does. Results showed that performance, GI-parasite burden, and biochemical and immunological parameters of pregnant does were influenced by the rearing system during winter.

Prevalence and seasonal dynamic of gastrointestinal parasites in equids in France during two years

Grazing equids are constantly exposed to three clinically important gastrointestinal parasites (small strongyles/cyathostomins, Anoplocephala spp. and Parascaris spp.). Knowledge of the local seasonal dynamic of these parasitic infections is important for constructing a sustainable parasite control program with a rational number of anthelmintic treatments. However, studies describing these patterns are sparse in France. In this context, a two-year study was carried out i) to assess the seasonal dynamic and variability of strongyle faecal egg counts (FEC) and infective larvae (L3) counts on pastures, and ii) the prevalence of Anoplocephala spp. and Parascaris spp. and the dynamic evolution of their presence. During 2021 and 2022 grazing seasons, monthly individual faecal egg counts (FEC) and diarrhea scores (DS) were determined on 428 equids divided into 33 groups. A monthly body condition score (BCS) was also attributed to animals ≥3 years old and a monthly bodyweight was estimated for each animal <3 years old. At the group level, the strongyle L3 counts on grazed pastures were carried out at least in spring, summer and autumn.Eggs of strongyles were observed in 97% of equids. In 64% of the groups, the peaks of FEC were noted in September and October. At the individual level, the maximum strongyle FEC was related to age, group of breeds, number of grazed plots and number of anthelmintic treatments. No negative association was observed between strongyle FEC and BCS or average daily weight gain.In the pastures, cyathostomin larvae were found almost exclusively. Over the two years, the peaks of cyathostomin L3 counts occurred in 87% of the groups between September and November and ranged from 635 to 87,500 L3 kg-1 dry herbage. The variability of the maximum cyathostomin L3 count in each group was explained by the year and the number of grazed plots.Eggs of Anoplocephala spp. were observed in 12% of equids. Eggs of Parascaris spp. were noted in 34% of one year-old animals, 9% of two years-olds and 2% of olders. Anoplocephala spp. and Parascaris spp. eggs were observed every month with a peak in the percentage of shedders in groups in October for Anoplocephala spp. and May-June for Parascaris spp.This study highlights the prevalence of each parasite, the variability in cyathostomin egg excretion and L3 counts amongst groups and individuals and the factors involved in this variation. These local epidemiological data will help us to re-think a newer strategy against these parasites.

Grazing weakens the linkages between plants and soil biotic communities in the alpine grassland

Livestock grazing alters the diversity and composition of plants and soil biota in grassland ecosystems. However, whether and how grazing affects plant-soil biota interactions are limited. Here, we performed a field investigation on the Tibetan grasslands to determine the relationships between plant community properties (biomass, diversity and richness) and soil biota (abundance, diversity and composition of bacteria, fungi and nematodes) in the long-term yak grazing and ungrazed plots, and responses of plant-soil biota linkages to grazing in alpine meadows and alpine swampy meadows were compared. The results found that grazing did not cause significant changes in plant community properties but increased the soil water content. Further, grazing weakened plant-soil microbes/nematode relationships in alpine meadows. The bacterial and fungal abundances were correlated with plant belowground biomass and Simpson index in the ungrazed plots of alpine meadows, while the correlation was not significant under grazing. Bacterial composition was correlated with plant richness only in the ungrazed meadows. Plant-soil nematode linkages were more sensitive to grazing than plant-microbes linkages. Grazing decoupled the relationships between the abundances of nematode trophic groups and plant aboveground biomass, richness and Simpson index in alpine meadows, while the decoupling phenomenon is less evident in alpine swampy meadows. The SEM results indicate that grazing altered the plant above- and belowground biomass to affect the soil nematode community, while influenced soil microbes only through alterations of plant belowground biomass. The findings highlight the importance of grazing in influencing the interactions between aboveground plant communities and soil biological communities in Tibetan grasslands.

PSIV-29 Performance and Resiliency Against Gastrointestinal Parasites of Pregnant Does and Ewes Raised Indoor and Outdoor During the Winter Season

Abstract Small ruminants in the southeast USA are mostly raised on pastures (outdoor) irrespective of seasons and associated weather conditions. During the extreme weather conditions, such as that occur in winter, animals may perform better while kept indoors. However, literature is scant on the benefits of keeping animals indoors during winter. The objective of this study was to assess the performance and resiliency against gastrointestinal (GI) parasites of pregnant does and ewes raised indoor and outdoor in winter. The experiment was conducted for 45 days from late January to mid-March 2023. Sixteen pregnant Kiko does, and eighteen pregnant Katahdin-St. Croix cross ewes were divided into two uniform groups. Group-1 animals (8 does and 9 ewes) were kept outdoors in a grazing plot that consisted of mobile shelters, mineral feeders, hay feeders, and watering troughs. Group-2 animals (8 does and 9 ewes) were kept indoors in individual pens with consisting of containers for providing water, minerals, hay, and grain. Both groups were given ad libitum hay, minerals, and water as well as corn-soybean mixed in 3:2 ratio at the rate of 0.8% of animal live weight. Ambient temperature and relative humidity (RH) were measured for both systems. Animal performance data [body weight, body condition score (BCS), and FAMACHA score] and fecal samples were collected on Day 1, weekly during the study, and at the end of the study. Fecal samples were analyzed for the type and quantity of GI parasites using the McMaster technique, and parasite eggs per gram of animal feces (EPG) was calculated. Weather data and animal performance data were analyzed using the GLM procedure and EPG data using the Wilcoxon Rank-Sum test in SAS 9.4. Temperature was higher (13.3%, P &amp;lt; 0.01) while RH was lower (6.25%, P &amp;lt; 0.01) in the indoor system. Ewes showed greater BCS (4.86%, P &amp;lt; 0.01) and does showed better FAMACHA score (8.5%, P &amp;lt; 0.01) in indoor system compared with outdoor ewes and does, respectively. Haemonchus contortus was found to be the major GI parasite affecting animals kept in both systems. Indoor ewes showed greater EPG than outdoor ewes (89.8%, P &amp;lt; 0.05). Results suggest that indoor rearing of pregnant does and ewes during winter can enhance their performance. Further research is needed to determine the possible reasons for greater EPG in pregnant ewes raised indoor vs. outdoor.

Spatial analysis and risk mapping of Fasciola hepatica infection in dairy cattle at the Peruvian central highlands

This study aimed to develop maps for Fasciola hepatica infection occurrence in dairy cattle in the districts of Matahuasi and Baños in the Peruvian central highlands. For this, a model based on the correlation between environmental variables and the prevalence of infection was constructed. Flukefinder® coprological test were performed in samples from dairy cattle from 8 herds, during both the rainy and wet season. Grazing plots were geo-referenced to obtain information on environmental variables. Monthly temperature, monthly rainfall, elevation, slope, normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), normalized difference water index (NDWI), distance to rivers, urban areas and roads were obtained by using remote sensor images and ArcGIS®. Multilayer perceptron Artificial Neural Networks modeling were applied to construct a predictive model for the occurrence of fasciolosis, based on the relationship between environmental variables and level of infection. Kappa coefficient (k > 0.6) was used to evaluate concordance between observed and forecasted risk by the model. Coprological results demonstrated an average prevalence from 20% to 100%, in Matahuasi, and between 0 and 87.5%, in Baños. A model with a high level of concordance between predicted and observed infection risk (k = 0.77) was obtained, having as major predicting variables: slope, NDWI, NDVI and EVI. Fasciolosis risk was categorized as low (p < 20%), medium (20% < p < 50%) and high (p ≥ 50%) level. Using ArcGIS 10.4.1, risk maps were developed for each risk level of fasciolosis. Maps of fasciolosis occurrence showed that 87.2% of Matahuasi area presented a high risk for bovine fasciolosis during the dry season, and 76.6% in the wet season. In contrast, 21.9% of Baños area had a high risk of infection during the dry season and 12.1% during the wet season. In conclusion, our model showed areas with high risk for fasciolosis occurrence in both districts during both dry and rainy periods. Slope, NDWI, NDVI and EVI were the major predictors for fasciolosis occurrence.

Can the inclusion of ribwort plantain or chicory increase the seasonal and annual dry matter production of intensive dairy grazing swards?

Pasture species complementarity leading to increased dry matter (DM) production has been observed in multispecies (MS) swards which include legumes and forage herbs along with grasses. This effect has been measured in mechanically defoliated plots with little data available from grazing scenarios. There is a scarcity of data available regarding individual forage herb species contribution to increased sward DM production where only plant functional group has been monitored previously. The objective of this three year study was to assess the DM production, N fertiliser response and change of botanical composition in grazed plots across nine MS sward mixtures compared to a PRG monoculture. Multispecies swards included various combinations of species from the three plant functional groups; N fertiliser treatments of 0, 100, 150 and 200 kg N/ha/year were applied. While year influenced the effect of sward mixture on annual DM production, swards that included white clover (Trifolium repens. L.) produced an average of 1688 kg DM/ha/year more than those which did not (P < 0.05); including forage herbs did not increase either annual or seasonal sward DM production. In the final year of the study sward chicory (Chicorium intybus. L.) content was 5% in mixtures including three plant functional groups while ribwort plantain (Plantago lanceolate. L.; PL) content was 37% in the same sward types. Although PL did not increase grazed sward DM production in the current study it did persist well under grazing and may provide other beneficial ecosystem services in dairy grazing systems.

Grazing regulates soil N cycling of annual pastures by enhancing soil N turnover in arid climate condition

AbstractNitrogen is the second limited factor in arid regions. Little information is available on soil N cycling and availability under grazing in arid regions, which is required to evaluate land‐use management with respect to soil N availability and dynamics. In 2011, we established a rotational grazing field experiment in arid grassland. We conducted experiments to explore the effects of herbivores grazing on soil net N mineralization and N processes via changes in soil temperature, moisture, pH, and microbial biomass nitrogen (MBN) in 2016 and 2017. Our results showed that grazing did not alter soil N mineralization because higher soil moisture and soil MBN under grazing had positive and negative effects on soil N mineralization, thereby balancing soil N mineralization. Plant N uptake at the grazing plots was, nevertheless, 23% higher than that at the non‐grazing plots. These demonstrated that grazing potentially improved soil inorganic N availability and alleviated soil N limitation in arid regions. Soil nitrification was main pathway of N transformation in arid regions. Grazing improved soil accumulation of NO3− content, resulting in environmental problems (such as N2O emission and N leaching); however, grazing had a little effect (~15% increase) on soil N leaching and (~7% decrease) on N2O emission. These N processes reflect important mechanisms of resilience and ecosystem stability under grazing in an N‐limited environment. Our results provide an important perspective for grassland management, aiming to maintain soil N supplying capacity in annual pasture sustainably. Overall, our study suggests that grazing is an effective management practice for the sustainable usage of local grasslands, as it improves soil physicochemical and biological properties, which, in turn, increases N supply.

Effects of winter grazing and N addition on soil phosphorus fractions in an alpine grassland on the Qinghai-Tibet Plateau

Nutrient cycling in alpine grasslands is susceptible to climate change and anthropogenic activities, which can affect soil phosphorus (P) availability. Despite the crucial role of soil P availability in maintaining stability and productivity of grassland ecosystems, limited research has been conducted on the effects of nitrogen (N) addition and winter grazing on P transformation on the Qinghai-Tibet Plateau. In an 8-year experiment, we applied four different N addition rates (0, 25, 50, and 100 kg urea ha−1 year−1) in combination with winter grazing to investigate the effects of N addition and winter grazing on the soil P fractions. The results reveal that increasing the N addition gradually reduced the resin-Pi and NaOH-Pi contents in the soil by increasing the plant P uptake and promoting the release of carboxylates in the rhizosheath, regardless of grazing. Winter grazing decreased the NaHCO3-Pi and NaOH-Pi contents compared with the no-grazing treatment by increasing the P uptake of the plants. In contrast, neither grazing nor N addition affected the HClconc.-P or residual-P content. In the no-grazing plots, the soil NaHCO3-Po content exhibited a gradual increase in response to N addition, whereas N addition had no discernible effect on the NaOH-Po content. In the grazing plots, the NaHCO3- and NaOH-Po contents gradually decreased with N addition, which was associated with the increased acid phosphatase activity in the rhizosheath and the export of forage. Thus, we conclude that N addition promotes the dissolution of NaOH-Pi to more available inorganic P forms. Under winter grazing conditions only, the transformation of P from inorganic to organic forms gradually decreased with increasing N additions.

Grazing in a megagrazer‐dominated savanna does not reduce soil carbon stocks, even at high intensities

Recent studies suggest that wild animals can promote ecosystem carbon sinks through their impacts on vegetation and soils. However, livestock studies show that intense levels of grazing reduce soil organic carbon (SOC), leading to concerns that rewilding with large grazers may compromise ecosystem carbon storage. Furthermore, wild grazers can both limit and promote woody plant recruitment and survival on savanna grasslands, with both positive and negative impacts on SOC, depending on the rainfall and soil texture contexts. We used grazing lawns in one of the few African protected savannas that are still dominated by megagrazers (&gt; 1000 kg), namely white rhinoceros Ceratotherium simum, as a model to study the impact of prolonged and intense wild grazing on SOC stocks. We contrasted SOC stocks between patches of varying grazing intensity and woody plant encroachment in sites across different rhino habitat types. We found no differences in SOC stocks between the most‐ and least grazed plots in any of the habitats. Intermediately grazed plots, however, had higher SOC stocks in the top 5 cm compared to most and least grazed plots, but only in the closed‐canopy woodland habitat and not in the open habitats. Importantly, we found no evidence to support the hypothesis that wild grazing reduces SOC, even at high grazing intensities by the world's largest megagrazer. Compared to the non‐encroached reference plots, woody encroached plots had higher SOC stocks in soils with low clay content and lower SOC stocks in soils with high clay content, although only in the top 5 cm. Accordingly, our study highlights that wild grazers may influence SOC indirectly through their impact on tree‐grass ratios in grassy ecosystems. Our study thus provides important insights for future natural climate solutions that focus on wild grazer conservation and restoration.Keywords: fire, grazing impact, rewilding, soil carbon, white rhinoceros, woody encroachment

Herbivores disrupt the flow of food resources to termites in dryland ecosystems.

Irruption of herbivore populations due to the extirpation of predators has led to dramatic changes in ecosystem functioning worldwide. Herbivores compete with other species for their primary source of nutrition, plant biomass. Such competition is typically considered to occur between species in closely related clades and functional groups but could also occur with detritivores that consume senescent plant biomass. In this study, we tested predictions that in ecosystems where herbivores are not regulated by predators, their indirect impacts on dead vegetation increase with primary productivity and extend to termites that feed on senescent vegetation. We compared dead vegetation cover and termite activity in herbivore exclosures and associated grazed plots at three locations situated along a rainfall gradient in arid Australia where kangaroo populations have irrupted. Dead vegetation cover and termite activity increased with rainfall in ungrazed plots but showed a negligible response to rainfall in grazed plots. Our results suggest that grazing can disrupt the flow of energy to detritivores and decouple the relationship between termite activity and primary productivity. Such disruption could have far-reaching impacts on arid ecosystems because many organisms sit within "brown food webs" that are sustained by energy derived from the decomposition of senescent plant tissues.

Soil amelioration induced by nurse shrubs in coal mines reclaimed to pastures and their synergistic effects with grazing

Native shrubs facilitate the establishment of oak seedlings in the opencast coal mines rehabilitated to pastures in Northern Spain, under a Mediterranean sub-humid climate. We evaluate soil changes as one of the possible facilitative effects of nurse shrubs. We hypothesize that nurse shrubs on mining soils can improve edaphic properties directly and indirectly by reducing the negative effects of trampling and grazing by ungulates. Thus, we assessed the combined effects of nurse shrubs (plots with vs without shrubs) and grazing (plots with vs without a fence for preventing browsing and trampling) upon soil properties in a reclaimed coal mine. Chemical properties such as electrical conductivity, K+, cation exchange capacity, and C/N ratio reached higher values beneath shrubs’ canopies, so did total organic matter, total N, total organic C, total P, available P, and Mg2+ under shrubs but only with grazing. In contrast, pH was higher outside the shrubs; also Ca2+, though only in the absence of grazing. With grazing, Na+ decreased under shrubs. Among physical properties, bulk density increased and porosity decreased only in grazed plots, whereas sand content increased under shrubs in the grazed plots, and clay decreased in such locations. Water holding capacity and available water were the highest in ungrazed areas. Overall, we found that shrubs have a positive direct effect on soil fertility, especially relevant in grazed areas because nurse shrubs and grazing have synergistic effects, and a positive indirect effect on physical properties because they attenuate negative effects of grazing, particularly soil compaction, by reducing livestock and wild ungulates trampling. Therefore, these results demonstrate how nurse shrubs contribute to soil amelioration, helping to facilitate plant establishment in reclaimed mines, which has relevant restoration implications for pasture and forest recovery.

Aridity threshold and grazing effects revealed by ecological interaction networks between leaf, root, and biomass function

Increasing aridity and grazing have multifaceted effects on the ecosystem, of which plant traits interact with each other to coregulate the productivity function including above- and below- ground compartments of plant. The ecological interaction network among plant traits could reflect how ecosystem interact with, influence, and respond to environment change. In this study, the interaction network between leaf, root, and biomass function was revealed to indicate systemic ecosystem response to increasing aridity and grazing by sampling in enclosed plots along the aridity gradient and in neighboring grazing plots of China drylands. Systemic and abrupt changes in the network relationship between leaf, root, and biomass were observed with a threshold value of 1-AI (aridity index) ∼ 0.8. The control effect of roots on other traits and the interaction of leaf and root compartments increased in the opposite direction above the threshold. The change in the relative importance of key traits with increasing aridity caused the different grazing effects. Grazing decreased the leaf area in the area with1-AI ∼ 0.6, whereas it increased the effect of roots in the area with 1-AI ∼ 0.8, thus promoting the interaction of functional traits. This result suggests the essential role of the interaction network between plant traits in ecosystem response to environmental change, which could indicate the ecosystem change in a holistic perspective under global change.

Growth and survival of Scots pine saplings under controlled grazing in forest plantation areas of the high altitude rangelands

This study was carried out to determine the effects of controlled cattle grazing in Scots pine (Pinus sylvestris L.) plantationthat in the edge of forest areas because animal husbandry has a significant role and forage gap is a main problem in the area. For this purpose, the study was carried out in a Scots pine plantation with an average of 2,160 m altitude in the forest edge rangeland area between 2012 and 2015. The study area was divided into 12 plots in total, with each plot 0.2 ha in size. The experiment was laid out in a randomized complete block design with three replications in a split plot arrangement keeping Scots pine sapling height (0–60 cm, 61–90 cm and &gt; 90 cm) and four grazing treatments (Ungrazed, grazed in June, grazed in July, grazed in August). The relative diameter and height increments were determined along with the survival percentages for the saplings. According to the results; overall, less than 1% of saplings were found to be damaged as a result of the treatments. In all the grazing plots, the Scots pine saplings had more diameter and height increment than the ungrazed plots on average. In conclusion, controlled cattle grazing in July and August can provide both good quality forage for regional livestock and positive contributions to the growth of saplings, provided that saplings have more than 60 cm in height. Keywords: Scots pine, plantation, sapling, growing, forest, grazing

Increased nutrient availability speeds up permafrost development, while goose grazing slows it down in a Canadian High Arctic wetland

Abstract It is of prime importance to understand feedbacks due to the release of carbon (C) stored in permafrost soils (permafrost‐climate feedback) and direct impacts of climatic variations on permafrost dynamics therefore received considerable attention. However, indirect effects of global change, such as the variation in soil nutrient availability and grazing pressure, can alter soil and surface properties of the Arctic tundra, with the potential to modify soil heat transfers toward the permafrost and impact resilience of Arctic ecosystems. We determined the potential of nutrient availability and grazing to alter soil energy balance using a 16‐year split‐plot experiment crossing fertilization at different doses of nitrogen (N) and phosphorus (P) with protection from goose grazing. Moss biomass and some determinants of the surface energy budget (leaf area index (LAI), dead vascular plant biomass and albedo) were quantified and active layer thaw depth repeatedly measured during three growing seasons. We measured soil physical properties and thermal conductivity and used a physical model to link topsoil organic accumulation processes to heat transfer. Fertilization increased LAI and albedo, whereas grazing decreased dead vascular plant biomass and albedo. Fertilization increased organic accumulation at the top of the soil leading to drier and more porous topsoil, whereas grazing increased water content of topsoil. As a result, topsoil thermal conductivity was higher in grazed plots than in ungrazed ones. Including these properties into a simulation model, we showed that, after 16 years, nutrient addition tended to shallow the active layer whereas grazing deepened mean July active layer by 3.3 cm relative to ungrazed subplots. As a result of OM accumulation at the surface, fertilization increased permafrost vertical aggradation rate by almost an order of magnitude (up to 5 mm year−1 instead of 0.7 mm year−1), whereas grazing slowed down permafrost aggradation by reducing surface uprising and deepening thaw depth. Synthesis. We demonstrated that long‐term grazing and N and P addition, through their impact on vegetation and soil properties have the potential to impact permafrost dynamics to the same extent as contemporary temperature increase in High Arctic polygonal wetlands.

Effect of grazing disturbance on floral display, pollen limitation and plant pollination efficiency in the desert steppe

BackgroundGrazing disturbance usually affects floral display and pollination efficiency in the desert steppe, which may cause pollen limitation in insect-pollinated plants. Effective pollination is essential for the reproductive success of insect-pollinated plants and insufficient pollen transfer may result in pollen limitation. Caragana microphylla Lam is an arid region shrub with ecological importance. Few studies have been conducted on how grazing disturbance influences pollen limitation and pollination efficiency of C. microphylla. Here, we quantify the effect of different grazing intensities on floral display, pollinator visitation frequency and seed production in the Urat desert steppe.ResultsIn C. microphylla, supplemental hand pollination increased the seed set, and pollen limitation was the predominant limiting factor. As the heavy grazing significantly reduced the seed set in plants that underwent open-pollination, but there was no significant difference in the seed set between plants in the control plots and plants in the moderate grazing plots. Furthermore, there was a higher pollinator visitation frequency in plants in the control plots than in plants in the heavy grazing plots.ConclusionsWe found that pollinator visitation frequency was significantly associated with the number of open flowers. Our findings also demonstrated that seed production is associated with pollinator visitation frequency, as indicated by increased seed production in flowers with higher pollinator visitation frequency. Therefore, this study provides insight into the effect of different grazing intensities on floral display that are important for influencing pollinator visitation frequency and pollination efficiency in desert steppes.

Effects of seasonal grazing on plant and soil microbial diversity of typical temperate grassland.

Biodiversity is the decisive factor of grassland ecological function and process. As the most important human use of grassland, grazing inevitably affects the grassland biodiversity. However, comprehensive studies of seasonal grazing on plant and soil bacterial, archaeal and fungal diversity of typical temperate grassland are still lacking. We examined the impact of seasonal grazing, including no-grazing (NG), continuous grazing (CG), grazing in May and July (G57), grazing in June and August (G68), and grazing in July and September (G79) on grassland plant and soil microbial diversity based on a long-term field grazing experiment. The results showed that the aboveground plant biomass (AGB) of the seasonal grazing plots was significantly higher than that of the CG plots. Compared with NG, CG increased significantly the Margalef richness index of plant community, while did not significantly change the Shannon, Simpson and Pielou evenness of plant community. Grazing changed the composition and biomass of dominant vegetation. Long-term grazing decreased the proportion of Leymus chinensis (Trin.) Tzvel. and increased the proportion of Cleistogenes squarrosa (Trin.) Keng. There was no significant change in the Shannoneven, Shannon and Coverage indices of soil bacteria, archaea and fungi between NG and the grazing plots. But the Chao index of soil fungi in G57, G68 and G79 and archaea in G57, G79 was significantly higher than that in CG. The results of correlation analysis showed that the plant diversity in the CG plots was significantly negatively correlated with the soil bacterial diversity. The plant richness in the G57 and G68 plots was significantly positively correlated with the soil archaea richness. Our study showed that seasonal grazing was a sustainable grazing management strategy for maintaining typical grassland plant and soil microbial diversity in northern of China.

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.

Different grassland managements significantly change carbon fluxes in an alpine meadow.

Alpine meadow plays vital roles in regional animal husbandry and the ecological environment. However, different grassland managements affect the structure and function of the alpine meadow. In this study, we selected three typical grassland managements including free grazing, enclosure, and artificial grass planting and conducted a field survey to study the effects of grassland managements on carbon fluxes in an alpine meadow. The carbon fluxes were observed by static chamber and environmental factors including vegetation and soil characteristics were measured simultaneously. Our results show that the alpine meadow was a CO2 and CH4 sink, and grassland managements had a significant effect on all CO2 fluxes, including gross ecosystem production (GEP, P< 0.001), net ecosystem production (NEP, P< 0.001) and ecosystem respiration (ER, P< 0.001) but had no significant effect on CH4 fluxes (P > 0.05). The ranking of GEP under the different grassland managements was enclosure > free grazing > artificial grass planting. Furthermore, NEP and ER at enclosure plots were significantly higher than those of the free grazing and artificial grass planting plots. In addition, different grassland managements also affected the vegetation and soil characteristics of the alpine meadow. The aboveground biomass of artificial grass planting was significantly higher than that of the free grazing and enclosure plots. The vegetation coverage under three different grassland managements was ranked in the order of enclosure > artificial grass planting > free grazing and significant differences were observed among them. Moreover, significant differences in the number of species (P< 0.01) and the Margalef richness index (P< 0.05) were detected under three different grassland managements. Further analysis of the relationship between environmental factors and carbon fluxes revealed that GEP and NEP of the alpine meadow were positively correlated with vegetation coverage, the number of species, and the Margalef richness index. Therefore, grassland restoration should be configured with multiple species, which could improve carbon sink capacity while considering the functions of grassland restoration and production.

When disturbances favour species adapted to stressful soils: grazing may benefit soil specialists in gypsum plant communities

Background Herbivory and extreme soils are drivers of plant evolution. Adaptation to extreme soils often implies substrate-specific traits, and resistance to herbivory involves tolerance or avoidance mechanisms. However, little research has been done on the effect of grazing on plant communities rich in edaphic endemics growing on extreme soils. A widespread study case is gypsum drylands, where livestock grazing often prevails. Despite their limiting conditions, gypsum soils host a unique and highly specialised flora, identified as a conservation priority. Methods We evaluated the effect of different grazing intensities on the assembly of perennial plant communities growing on gypsum soils. We considered the contribution of species gypsum affinity and key functional traits of species such as traits related to gypsum specialisation (leaf S accumulation) or traits related to plant tolerance to herbivory such as leaf C and N concentrations. The effect of grazing intensity on plant community indices (i.e., richness, diversity, community weighted-means (CWM) and functional diversity (FD) indices for each trait) were modelled using Generalised Linear Mixed Models (GLMM). We analysed the relative contribution of interspecific trait variation and intraspecific trait variation (ITV) in shifts of community index values. Results Livestock grazing may benefit gypsum plant specialists during community assembly, as species with high gypsum affinity, and high leaf S contents, were more likely to assemble in the most grazed plots. Grazing also promoted species with traits related to herbivory tolerance, as species with a rapid-growth strategy (high leaf N, low leaf C) were promoted under high grazing conditions. Species that ultimately formed gypsum plant communities had sufficient functional variability among individuals to cope with different grazing intensities, as intraspecific variability was the main component of species assembly for CWM values. Conclusions The positive effects of grazing on plant communities in gypsum soils indicate that livestock may be a key tool for the conservation of these edaphic endemics.