Ungrazed Treatments Research Articles

Integrating grazing and food supplementation in coral restoration to enhance settler survival and growth

Sexual coral propagation faces a significant bottleneck due to high post‐settlement mortality, impeding large‐scale reef restoration. This study assessed the effectiveness of co‐culturing Diploria labyrinthiformis settlers with the herbivorous gastropod Cerithium lutosum and supplementing their diet with a commercially available food source, Reef‐Roids, to enhance settler survival and growth. Settlers were reared for 10 weeks under controlled conditions in one of four treatments: Control (C), Feeding with Reef‐Roids (F), Grazing by C. lutosum (G), and combined Feeding + Grazing (FG). Settlers in the Grazing treatment exhibited the highest survival at 87% after 10 weeks, significantly outperforming those in the Control (43%) and Feeding (48%) treatments. The combined feeding and grazing treatment improved survival rates to 74% and resulted in the highest growth rates, with settlers in this group averaging 11.98 ± 2.38 mm2, approximately 3.4‐fold larger than the control and 2.6‐fold larger than the feeding group. The feeding treatment alone did not significantly enhance survival or growth, underscoring the critical role of grazing in mitigating algal competition and promoting settler development. The results highlight the efficacy of grazing by C. lutosum (G and FG) in improving both survival and growth of coral settlers, substantially surpassing the outcomes of ungrazed treatments (F and C). This study highlights the potential of integrating microherbivores, such as C. lutosum, in ex situ coral nurseries. By regulating algal growth, these grazers minimize the need for labor‐intensive maintenance, offering a scalable and cost‐effective strategy to mitigate the high mortality rates of coral settlers.

397 Effect of corn harvest with a chopping head on performance of cattle grazing corn residue

Abstract The addition of stalk chopping equipment on combine heads has become more common. An advantage of grazing residue compared with baling, is the ability of cattle to select the more digestible plant parts (husk and leaf). Chopping may impact this ability and decrease the feeding value. Thus, this study was designed to evaluate the effects of chopping residue at harvest on grazing cattle performance. A cornfield (16 Mg grain/ha) was divided into 12 paddocks blocked by location within field and assigned randomly to be harvested using a chopping or non-chopping combine head, with 4 paddocks assigned to be grazed (1.05 ha) from each harvest method (HM) and 4 ungrazed. Growing steers [n = 40; body weight (BW) = 230 ± 3.5 kg] were stratified by BW and assigned randomly to a grazed paddock, with 6 steers in the west block and 4 steers in the east block, with 1 rumen canulated steer (484 ± 33 kg BW) being assigned to each of the east paddocks and used as diet samplers. This resulted in the same grazing pressure (2.9 animal units/ha) in grazed paddocks. Cattle were supplemented at 0.6 % of initial BW with a distillers dried grains plus solubles and mineral mix daily. Cattle grazed for 56 d resulting in 5.4 Animal Units Months/ha. Residue mass of three 0.58 m2 frames was sampled in each paddock before (d -1), during (d 36) and after grazing. Husks were collected from three 5.81 m2 areas per paddock at each of the three timepoints. For residue mass, there was a significant (P < 0.01) HM by time interaction. There was no difference (P = 0.34) in residue mass between HM prior to grazing. However, at 36 d into grazing, residue mass of standard was greater (P = 0.03) than chopped, and post-grazing residue mass of chopped was greater (P = 0.01) than standard. When husk (kg/ha) was evaluated, there was a significant (P < 0.01) HM by time by grazing interaction. Prior to grazing, there was no difference (P ≥ 0.66) in husk between the grazed and ungrazed paddocks within HM. However, husk was less (P < 0.01) for chopped than standard. On d 36, within HM, grazed had less (P < 0.01) husk than the ungrazed. However, within grazing status on d 36 there was no effect (P ≥ 0.52) of HM. Post-grazing there were no differences (P ≥ 0.19) in husk among treatments. Within grazed treatments there was greater (P < 0.01) husk prior to grazing initiation compared with both D36 and post-grazing which did not differ (P ≤ 0.85). Within ungrazed treatments, pre-grazing and D36 did not differ (P ≥ 0.10) in husk, however, husk was lesser (P > 0.01) at the post-grazing sampling. For ADG there was no difference (P = 0.20) between HM, with 0.37 and 0.31kg/d for standard and chopped, respectively. Overall, HM had no effect on grazing cattle performance.

Fire and grazing interaction in a subhumid grassland: Effects on a dominant tussock grass

AbstractQuestionsHerbivory and fire are the main disturbance drivers in open ecosystems. The aim of this study was to evaluate the effects of fire, cattle grazing, and their interaction on structural traits and the Normalized Difference Vegetation Index (NDVI) of the tussock grass Saccharum angustifolium, and its temporal dynamics in a subhumid grassland.LocationGrasslands of the Eastern Hills, Uruguay.MethodsWe set three blocks (four plots of 300 m2 each) in a homogeneous grazed area dominated by S. angustifolium within a protected area. Each block presented the combinations that emerged from the two levels of cattle grazing (grazed/ungrazed) and burning (burned/unburned) factors. The experimental burning was carried out in the spring. Clump volume, number of flowering culms, NDVI of S. angustifolium, and soil variables were measured for 2 years.ResultsBurning efficiency (plant biomass burned of the total available) was 82%, burn intensity ranged from 178–610 kW m−1, and the soil temperature increased 40% compared with pre‐fire measurements. The volume of S. angustifolium clumps decreased with fire, and the difference between burned–unburned plots decreased with time. The burned–ungrazed treatment increased the number of S. angustifolium flowering culms. NDVI of S. angustifolium clumps increased 50% with fire, and then decreased with time. Soil temperature was higher in burned treatments, and moisture was higher in unburned treatments on some dates. Bulk density, for the 0–5‐cm depth, was 9% higher in burned than in unburned plots irrespective of grazing.ConclusionsOur results provide new data in favor of the management practice carried out by ranchers in Uruguayan grasslands dominated by S. angustifolium. Our data complement the evidence that a fire–grazing interaction can maintain grasslands in different phases of a stable state. Our results constitute a useful contribution for the managers/authorities of the protected area, and can be extrapolated to other tussock grass‐dominated grassland areas.

89 Improving cattle grazing efficiency with multi-functional cover crops

Abstract Grazing cool-season cover crops provides a sustainable way of extending the grazing season and reducing the impact row-crop farming systems on the environment. Cover crops promote soil health; however, the impacts of grazing cover crops on soil health in the Southeast are not well understood. The objective of the current study was to determine the effects of different cover crop mixtures on a cotton (Gossypium hirsutum)-peanut (Arachis hypogaea) cropping system. The experiment consisted of 18 paddocks, planted in mixtures of grass [‘Coker’ oat (Avena sativa)], grass + legume [‘Dixie’ crimson clover (Trifolium incarnatum)], or grass + legume + brassica [(‘T-raptor’ brassica (Brassica napus × B. rapa)] planted at the Wiregrass Research and Extension Center (Headland, AL). Paddocks were randomly allocated to grazed or not grazed (n = 3). Grazed paddocks were grazed with yearling beef steers (266 ± 44 kg) using the put and take method to maintain a forage alloance of 1 kg DM per kg BW. Forage samples were collected every 2 wk, for biomass, botanical compositions, and nutritive value. Paddocks were grazed from 17 Jan – 22 Mar 2023 (65 d) and steer BW were taken at the beginning and end of the grazing season for calculation of average daily gain Data were analyzed using Proc Glimmix of SAS 9.4 (SAS Institute, Cary, NC) with forage sampling date considered a repeated measure. No difference in steer average daily gain was detected among grazed treatments (1.5 kg/d; P > 0.44). Cover crop (forage) biomass was also not different among all grazed and ungrazed treatments (1,097 kg DM/ha; P = 0.56). According to the results, grazing cool-season annual cover crops may reduce the supplementation required to maintain cattle through the winter months in the Southeast.

Long-term fire and grazing regimes modify soil physical properties and root traits in North American tallgrass prairie

The native Konza tallgrass prairie is maintained by two key natural processes, periodic fire and ungulate grazing. As a potential crucial feedback mechanism, how fire and grazing influence plant root traits and soil properties in the tallgrass prairie ecosystem remains less known. Here, we investigated the effects of long-term fire and grazing regimes on soil physical properties and root traits at the Konza Prairie Biological Station, near Manhattan, KS, USA. Soil cores were collected under control (unburned and ungrazed), fire (annually burned), grazing (annually grazed), and fire + grazing (annually burned and grazed) treatments. Soil water retention, total root volume, specific root length, specific root area, and root biomass were measured. We found that both fire and grazing significantly reduced soil water retention, increased soil bulk density and soil microporosity (<50 μm), and reduced macroporosity (>50 μm) compared to the unburned and ungrazed treatment. Fire and grazing also significantly reduced litter accumulation by 79 % (burned), 57 % (grazed), and 77 % (burned and grazed). Fire increased specific root area by 15 %. Grazing and fire + grazing significantly decreased specific root length by 40 % and 29 %, and specific root area by 33 % and 24 %, respectively. Litter production was positively related to soil volumetric water content and soil pore volume of 300–50 μm, but negatively related to soil bulk density and soil pore volume of less 50 μm. Soil volumetric water content was positively correlated to specific root lengths, and soil bulk density was negatively related to specific root length and specific root area. There was a significant negative relationship between root diameter and soil volumetric water content under burned and grazed treatment. The SEM model showed that fire, grazing, and fire + grazing regimes were associated with dead root biomass (R2 = 0.38) and root length density (R2 = 0.40) indirectly through soil bulk density and litter accumulation. Our findings suggested that the annual fire + grazing regime seriously leads to the degradation of tallgrass prairie by influencing soil physical properties, reducing root trait functions and root biomass, and altering the relationship between root diameter and soil volumetric water content.

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

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

Integrated crop and livestock systems increase both climate change adaptation and mitigation capacities

Integrated crop-livestock systems (ICLS) are proposed as key solutions to the various challenges posed to present-day agriculture which must guarantee high and stable yields while minimizing its impacts on the environment. Yet the complex relationships between crops, grasslands and animals on which they rely demand careful and precise management. In this study, from a 18-year ICLS field experiment in Brazil, that consists in annual no-till soybean-pastures grazed by beef cattle, we investigated the impacts of contrasted pastures grazing intensities (defined by sward heights of 10, 20, 30 and 40 cm, plus an ungrazed treatment) on the agroecosystem productivity and soil organic carbon (SOC) under both historical and future (2040–2070, RCP8.5) climatic conditions. We used an innovative methodology to model the ICLS with the STICS soil-crop model, which was validated with field observations. Results showed that the total system production increased along with grazing intensity because of higher stocking rates and subsequent live weight gains. Moderate and light grazing intensities (30 and 40 cm sward heights) resulted in the largest increase in SOC over the 18-year period, with all ICLS treatments leading to greater SOC contents than the ungrazed treatment. When facing climate change under future conditions, all treatments increased in productivity due to the CO2 fertilization effect and the increases in organic amendments that result from the larger stocking rate allowed by the increased pasture carrying capacity. Moderate grazing resulted in the most significant enhancements in productivity and SOC levels. These improvements were accompanied by increased resistance to both moderate and extreme climatic events, benefiting herbage production and live weight gain. Globally, our results show that adding a trophic level (i.e. herbivores) into cropping systems, provided that their carrying capacities are respected, proved to increase their ability to withstand climate change and to contribute to its mitigation.

420 Integrating Livestock and Cropping Systems: Interseeding Cereal Rye into Corn for Late Season Grazing

Abstract The objective of this project was to evaluate the effect of interseeding cereal rye (Secale cereale) into corn (Zea mays) for use as grazed forage after corn grain harvest on corn grain yield and additional grazing day· ha-1. In a 4-year study, corn was planted (64,246 plants· ha-1) in spring on two, 4.8-ha fields in central Pennsylvania. Cereal rye was interseeded (135 kg· ha-1) into the corn at the V4-V6 stage. Corn was harvested as grain in November and each field was divided into six, 0.8-ha paddocks and randomly assigned to either grazed (GRAZ) or ungrazed (NG) treatments. Beef cattle frontal-grazed three of the paddocks (four cows· paddock-1) in each field approximately four to five weeks after corn grain harvest and, if re-growth allowed, again in early spring before subsequent corn planting. Corn grain, corn fodder (after grain harvest), and cereal rye yields were monitored each fall. Cereal rye growth was also monitored in early spring. Statistical analyses on corn grain yield and forage biomass were conducted using the MIXED procedure in SAS 9.4 (SAS Institute, Cary, NC, USA). Least square means were separated using Fisher’s least significant difference test (α = 0.05). There were no site by treatment interactions, therefore means are presented as an average across both sites (Table 1). Corn grain, corn stover, and cereal rye yields were affected by year. Corn grain yields did not decrease as a result of grazing, or of repeated plantings of corn, ranging from 9,516-10,088 kg· ha-1 across GRAZ and NG paddocks except in 2019 (dry year) when corn grain yields averaged 6,053 kg· ha-1 across both GRAZ and NG treatments. Spring grazing only occurred in one year (2021) due to insufficient cereal rye growth in the other years. On average, the cereal rye (plus the corn stover) provided enough forage for an additional 115-130 grazing days· ha-1 in the fall. Results of this study showed that when corn is harvested too late in the year to establish a cover crop, interseeding annual forages into growing corn provides winter ground cover and an opportunity for late season grazing. Interseeding cereal rye into the corn did not negatively impact corn grain yields with repeated corn planting. While early spring growth of the cereal rye has the potential to provide even greater forage yields than fall, it is much less dependable than fall due to the potential of delayed spring growth or lack of winter precipitation under the conditions of the current study.

Grazing intensity effects on herbaceous community composition in burned sagebrush steppe

AbstractThere is limited knowledge of grazing impacts on longer term plant community dynamics following fire in sagebrush steppe. This study evaluated vegetation response to different intensities of deferred rotation cattle grazing over 16 years (2007–2022) on burned Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis (Beetle &amp; Young) Welsh) steppe in eastern Oregon. Treatments were applied in a randomized complete block, which included no grazing on burned (nonuse, n = 5) and unburned (control, n = 5) steppe; and cattle grazing at low (low, n = 4), moderate (moderate, n = 4), and high (high, n = 4) intensities on burned steppe. Vegetation dynamics were evaluated by repeated measures analysis of canopy cover and density of shrub and herbaceous species and functional groups. Herbaceous functional groups were an early‐season bunchgrass (one species, Sandberg bluegrass [Poa secunda J. Presl]), tall perennial bunchgrasses, perennial forbs, annual grass (one species, cheatgrass [Bromus tectorum L.]), and annual forbs. Tall perennial bunchgrass, Sandberg bluegrass, and perennial forb cover and density did not differ among the treatments but did decrease over time in all treatments. The cover of several tall bunchgrass species was generally less in the high treatment, mainly, Idaho fescue (Festuca idahoensis Elmer) and Thurber's needlegrass (Achnatherum thurberianum (Piper) Barkworth). The cover of cheatgrass and annual forbs varied among years but was greater in the burned‐grazed and nonuse treatments than in the control. Native plant cover in the burned treatments (grazed and nonuse) represented 77%–85% of total herbaceous cover versus the control where native plants comprised 91% of the total. Annual weather variability appears to account for most of the compositional dynamics measured in the various grazed and ungrazed treatments.

Livestock grazing is an effective conservation tool for Californian coastal grassland ecology: An eight‐year study on vegetation dynamics

AbstractQuestionsLivestock grazing is an expanding land management tool for habitat and fuel management in California grassland ecosystems, despite mixed conclusions about its effects. Our study investigated the following questions: Does a targeted grazing regime promote grassland functioning by clearing bare ground and reducing dead litter cover? Does targeted grazing reduce grassland fuels? Does targeted grazing promote native species cover and diversity? Does targeted grazing reduce non‐native, invasive species cover and diversity? LocationThe Santa Lucia Preserve, Carmel, California, USA.MethodsMonitoring grazed and ungrazed treatment plots within 17 study sites, we surveyed the effects of a targeted grazing regime on bare ground cover, litter cover and depth, herb height, and diversity and cover of different native and non‐native species groups over an eight‐year period.ResultsOn average, grazing successfully increased bare ground (by 2.8% cover), decreased litter depth (by 3.5 cm) and cover (by 12%), and decreased herb height (by 3.9 cm). Grazed plots had greater cover of native annual forbs (+1.2% cover), while decreasing invasive Bromus diandrus (by 6.0% cover). There was no difference in either native or non‐native species diversity.ConclusionsTargeted grazing can be an appropriate tool to accomplish conservation goals, including biomass management and canopy clearing, while improving native annual forbs without risk to native species as a whole. Further steps in adaptive management must examine how the application of grazing may be altered to further promote native species and to inhibit invasive species.

Moderate Grazing During the Off-Season (Fall-Winter) Reduces Exotic Annual Grasses in Sagebrush-Bunchgrass Steppe

Exotic annual grass invasion and dominance of sagebrush-bunchgrass steppe is a concern because it decreases biodiversity and promotes frequent wildfires. Management is needed to reduce exotic annual grasses to prevent sagebrush-bunchgrass communities from transitioning to annual grasslands. Grazing during the off season (fall-winter) has shown promise at reducing exotic annual grasses, but it has not been evaluated in plant communities dominated by sagebrush and native bunchgrasses. We compared moderate grazing during the off season with not grazing in five Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis [Beetle & A. Young] S.L. Welsh)−bunchgrass communities in the northern Great Basin. Treatments were applied annually for 10 yr (2009−2010 through 2018−2019). Plant community characteristics were measured after treatments had been applied from 6 to 10 yr. Off-season grazing reduced exotic annual grass density and cover. After a decade, annual grass cover was twofold greater in ungrazed areas. Sandberg bluegrass (Poa secunda J. Presl) density increased with off-season grazing, but large bunchgrass density was similar between off-season grazed and ungrazed areas. Perennial and annual forb density and cover were similar between off-season grazed and ungrazed treatments. Biological soil crust cover was also similar between off-season grazed and ungrazed areas. The results of this study provide strong evidence that off-season grazing has application for managing exotic annual grasses in sagebrush-bunchgrass steppe. Considering the vast scope of the exotic annual grass problem, properly applied grazing may be the most cost-efficient tool to mediate the impacts of annual grass invasion.

Long-term effects of grazing intensities on soil aggregation and organic matter in a no-tilled integrated soybean-cattle system

Grazing intensity in integrated crop-livestock systems (ICLS) can affect soil aggregation and C stabilization and, consequently, the soil condition and agricultural sustainability. This study evaluate the influence of 13 years of different grazing intensities on (i) soil aggregation, (ii) C content in different aggregate size, and (iii) C and N content in different fractions of soil organic matter (SOM), in a no-tilled with integrated soybean-beef production system on a subtropical Oxisol. Treatments consisted of four steers grazing intensities defined by sward height of 10, 20, 30 and 40 cm on mixed black oat and Italian ryegrass pasture in the winter under continuous stocking, plus an ungrazed treatment, in a randomized complete block design with three replicates. Soil aggregation was not affected by grazing intensities. There was no effect of the grazing intensities on organic C content in all aggregate-size fractions and in all soil layers evaluated, being lower in microaggregates than in large and small macroaggregates. The macroaggregates were predominant, representing 97% of the soil mass, of which 74% were large macroaggregates (>2 mm). The high macroaggregates stability contributed to the lack of difference in the C and N content on free light fraction and the light occlusal fraction of SOM. Most of C and N were observed heavy fraction of SOM (53–68%), with greater stock in the no grazing compared to the grazed treatments. Even with the animal trampling in the grazed systems, the soil maintained high stability of aggregates and consequently the labile forms of SOM.

Forb community response to prescribed fire, livestock grazing, and an invasive annual grass in the Pacific Northwest Bunchgrass Prairie

AbstractQuestionsGrassland degradation due to agriculture, changing fire regimes, and invasive species negatively affects forb communities. Conserving forbs and the services they provide requires a better understanding of their responses to interacting disturbances. Although fire and livestock grazing are important disturbances, their effect on forb communities in the Pacific Northwest Bunchgrass Prairies is not fully understood. Our objectives were to: (a) determine how prescribed fire and livestock grazing influence forb community composition, cover, species richness, and diversity over a 10‐year span; (b) identify indicator species for each treatment; and (c) quantify forb responses to increasing cover of the invasive grass Ventenata dubia.LocationPacific Northwest Bunchgrass Prairie, Oregon, USA.MethodsWe monitored plant responses in a manipulative study established in 2004 with four treatments (prescribed fire, livestock grazing, both fire and grazing, and a control with no fire or grazing). Fall burns occurred in 2006 and 2016.ResultsForb communities changed significantly over 10 years and were influenced more by fire than cattle grazing. Treatments involving fire were more associated with annual forbs and fewer perennial species than treatments not burned. Although forb cover was lower in grazed compared to ungrazed treatments, richness and diversity did not differ among treatments. Several fire‐adapted forb species were associated with burned treatments. Forb cover and richness was negatively correlated with Ventenata dubia cover in 2016 and 2018 when cover of this invasive species reached 20%–37%.ConclusionsWe found fall prescribed burns at a ten‐year return interval affected forb community composition and cover but not richness or diversity. Fire may promote annual and fire‐tolerant perennial forbs, but this relationship may be compromised by Ventenata dubia invasions. This study provides insights into management strategies aimed at conserving forb communities and emphasizes the need for continued monitoring of the Ventenata dubia invasion in this unique prairie.

N deposition may accelerate grassland degradation succession from grasses- and sedges-dominated into forbs-dominated in overgrazed alpine grassland systems on Qinghai-Tibetan Plateau

Alpine grasslands are sensitive to grazing and atmospheric nitrogen (N) deposition. Despite increases in N deposition, few field studies have assessed the effects of grazing in conjunction with increased N deposition on alpine grassland vegetation.In this two-year field study, we examined the effects of overgrazing and overgrazing plus N deposition on eco-physiological processes of alpine grassland plants at the functional group level. We found that both overgrazing and overgrazing plus N deposition altered species composition and the dominance of three plant functional groups (grasses, sedges, and forbs) in an alpine meadow and alpine steppe.In the overgrazing and overgrazing plus N deposition treatments, forbs dominated the plant community. Grass and sedge dominance decreased substantially, relative to a ungrazed treatment. The underlying eco-physiological processes that led to the forb-dominated plant community differed between the overgrazing and overgrazing plus N deposition treatments. Overgrazing plus N deposition increased forb dominance both directly by selective herbivory and indirectly by enhancing forb photosynthetic rates.Our results suggest that overgrazing concomitant with increases in N deposition will likely shift the plant community composition of alpine grasslands on the Qinghai-Tibetan Plateau from grass/sedge communities to forb-dominated communities in the future.

Intense winter grazing impairs subsequent Italian ryegrass re‐establishment in soybean‐pasture rotations

AbstractWe evaluated Italian ryegrass (Lolium multiflorum Lam.) establishment in a factorial of grazing intensity (intense, moderate, moderate‐light, light, and no grazing, with target average sward heights of 10, 20, 30, and 40 cm in the grazed plots) and additional seeding (self‐seeding with or without additional seeding) in an integrated soybean‐beef cattle system in southern Brazil. Grazing treatments were imposed in winter (June–July) and followed by a direct‐seeded soybean crop (November). The establishment was quantified prior to the stocking periods in 2017 and 2018, corresponding to self‐seeding from 2016 and 2017. Intense grazing impaired ryegrass re‐establishment, resulting in larger individual plants (0.54 vs. 0.15 g dry matter plant−1) but lower population density (57 vs. 1,355 plants m−2) than in the other treatments. Additional broadcast ryegrass seeding did not fully compensate for the reduced natural reseeding in this treatment. The addition of seeds under intense grazing increased plant population density to values comparable to moderate grazing intensities but reduced individual plant mass, limiting herbage mass attained by the end of the pasture establishment phase. Contrastingly, the various combinations of individual plant mass and population density were sufficient to maintain herbage masses in moderate to light grazing intensities that were comparable to that in the ungrazed treatment, regardless of seed addition (63 vs. 180 g DM m−2 for intense grazing vs. the average of other treatments over the whole establishment phase). Moderate grazing, e.g., target sward heights of 20 cm or greater, is necessary to achieve a system that can sustain itself without seed addition.

Microbial community structure across grazing treatments and environmental gradients in the Serengeti

As one of the last remaining naturally grazed ecosystems on Earth, the Serengeti National Park is an ideal location to study the influence of migratory mammals on the structure of microbial communities and the factors that generate biogeography of soil microbes. Furthermore, volcanic inputs generate environmental gradients that may also structure microbial communities. We studied 16S rRNA amplicons in a 13-year herbivore removal experiment to examine the influence of grazing and environmental gradients on the natural distribution of soil microbes. Removal of mammalian herbivores shifted microbial community structure, with 31 taxa that were significant indicator taxa of the ungrazed treatment and three taxa that were indicators of the grazed treatment. The abundance of many taxa were correlated with soil texture, phosphorus, iron, calcium and rainfall, and the evenness of taxa within samples was also correlated with these variables. Bayesian general linear mixed effects models with single predictors of multiple, highly correlated variables of beta diversity were consistent with a significant, but weak (2%), effect of grazing, and stronger effects of phosphorus (14%). Beta diversity of microbial communities was greater in grazed than in ungrazed plots; suggesting that the impacts of grazing on community assembly of microbes results from deterministic environmental filtering caused by the influence of herbivores on plant communities and soil properties rather than stochastic dispersal via herds of large mammals. These herbivore effects are superimposed on deterministic environmental filtering by natural soil and precipitation gradients across the Serengeti.

Livestock grazing impacts components of the breeding productivity of a common upland insectivorous passerine: Results from a long‐term experiment

Abstract The intensity of pastoral management in areas of High Nature Value farming is declining in some regions of Europe but increasing in others. This affects open habitats of conservation concern, such as the British uplands, where bird species that benefit from low‐intensity grazing may be most sensitive to such polarization. While experimental manipulations of livestock grazing intensities have improved our understanding of upland breeding bird responses in the short term, none have examined the long‐term impacts of altered management on reproductive success. Using a replicated landscape‐scale experiment that started in 2003, we investigated the effects of four grazing treatments (intensive sheep; low‐intensity sheep; low‐intensity mixed sheep and cattle; and no grazing) on the breeding productivity of meadow pipits Anthus pratensis, the most common upland passerine. Surveys were carried out systematically during early (2003 and 2004) and late (2015 and 2016) sampling periods of the experiment to compare the short‐ and long‐term effects of grazing treatments on breeding density and productivity of pipits specifically, but also on the overall bird community. Pipit breeding density was lowest under low‐intensity sheep grazing while the highest egg‐stage nest survival was observed in the same treatment, although no significant treatment effects were detected on overall nest survival or fledgling output. There were no significant differences in treatment effects between the sampling periods on any breeding variable, but overall nest survival was lower in the later sampling period across all treatments. Breeding bird species richness differed between treatments in the later sampling period, with highest species richness in the ungrazed treatment. Synthesis and applications. Livestock grazing management can have different outcomes for different upland birds. Our results showed that, with time, meadow pipit breeding productivity tended to be higher when sheep grazing intensity was reduced and/or mixed with cattle, and lower when livestock were removed, but not significantly so. Removal of grazing, however, can significantly increase bird species richness. The long‐term experiment showed an overall decline in fledglings regardless of grazing treatments, potentially a result of increased predator numbers harboured by nearby developing woodland, highlighting the importance of considering wider landscape processes in grazing management decisions.

Populations of Small Mammals, Tallgrass Prairie and Prescribed Fire: A Fire-Reversal Experiment

We sampled small mammals in burned and unburned tallgrass prairie by using three sites in each of two contiguous ungrazed experimental fire-reversal treatments during 1999-2010. One of the experimental treatments (001A to R20A) had been burned in spring for >20 years and then was switched to an unburned research treatment after the spring fire in 2000. In contrast, the other treatment (020A to R01A) had been left unburned for 20 of 29 years before it was switched to an annually burned treatment beginning with the prescribed fire in spring 2001. Overall, we recorded 11 species of rodents and two of shrews for a total of 2,444 individuals. The white-footed mouse (Peromyscus leucopus) was the most abundant species followed by the hispid cotton rat (Sigmodon hispidus) and deer mouse (P. maniculatus). Of the seven common species (>25 individuals), six were strongly associated with one of the treatments, and several species showed positive associations with some part of the landscape within each treatment. Furthermore, white-footed mice, deer mice, prairie voles (Microtus ochrogaster), western harvest mice (Reithrodontomys megalotis) and Elliot's short-tailed shrews (Blarina hylophaga) showed significant temporal patterns of abundance in either R01A or R20A in one or both seasons (autumn or spring). Our study also supports a very important conservation message. That is, the white-footed mouse (a woodland species) and the hispid cotton rat (a colonizing species) were more numerically dominant than the most common rodent, the deer mouse, (a native prairie species) throughout the 10-year study. These observations demonstrate that areas not burned frequently allow encroachment by shrubs and then trees, which subsequently allow the white-footed mouse and hispid cotton rat to expand into these areas. Conversely, the stoppage of frequent fires ultimately degrades the mosaic of prairie habitats for native prairie small mammals [such as the deer mouse, prairie vole and western and plains harvest mice (R. montanus)] and these species move out as shrubs and trees become common. Visual observations indicate that the latter (degradation of native tallgrass prairie) occurs much more rapidly (potentially within a decade) than the restoration of native tallgrass prairie by the elimination of shrubs and trees by annual burning (potentially 50 or more years).

Grazing affects snow accumulation and subsequent spring soil water by removing vegetation in a temperate grassland

By altering plant and soil properties and microclimate environments, grazing has a profound influence on the structure and function of grassland ecosystems. However, few studies have addressed the potential grazing effects on snow accumulation and subsequent spring soil water after snow melting and soil thawing. In this study, vegetation properties, snow accumulation and soil water were measured in experimental plots subjected to 8 years of cattle grazing comprising six different grazing intensity treatments in a typical temperate grassland in eastern Eurasia. The results indicated that heavy grazing reduced the snow depth by 51% and the snow mass by 40%. Snow accumulation first rapidly increased but then remained relatively stable with increases in both the aboveground biomass and canopy height. An obvious inflection point occurred at approximately 200 g m−2 aboveground biomass and at a 12.5 cm canopy height. The obvious difference in soil water content between the heavily grazed and ungrazed treatments occurred mainly in the spring after snow melting and soil thawing. The spring soil water content (0–30 cm) reached 31.5% in the ungrazed treatment (G0), which was 1.7 times that in the heavily grazed treatment (G0.92). The soil water content increased exponentially with increasing vegetation properties (aboveground biomass, canopy height and canopy cover), and a similar trend occurred with increasing snow mass and snow depth. Our structural equation modeling showed that both vegetation properties and snow accumulation had significant positive effects on spring soil water. By removing vegetation, grazing at increased intensities had significant, indirect suppressive effects on snow accumulation and spring soil water. Therefore, to obtain increased amounts of snow accumulation and spring soil water, land managers should consider reducing the grazing intensity or leaving some plots ungrazed.

Winter grazing does not affect soybean yield despite lower soil water content in a subtropical crop-livestock system

Commercial-scale integrated crop-livestock systems intensify land use by combining complementary agricultural enterprises and leveraging synergistic ecosystem services to achieve both productive and environmental outcomes. Although widely implemented in southern Brazil as an annual beef/soybean rotation, tradeoffs such as competing soil water use between pasture and crop phases may result from seasonal grazing in this system. We compared soil water and plant physiological variables in the crop phase of an integrated annual beef-soybean system managed with no-till and best grazing practices with those of an ungrazed cover crop control as part of a long-term experiment in southern Brazil. A mixed black oat (Avena strigosa Schreb.) and Italian ryegrass (Lolium multiflorum Lam.) pasture was either grazed by beef cattle to 20-cm sward height or left as an ungrazed cover crop in the winter, and direct-planted to soybean (Glycine max [L.] Merr.) in the summer. Although soybean yields did not differ between grazed and ungrazed treatments, soil matric potential was on average 25% lower across depths and growth stages in plots that had been grazed during winter. Soybeans in grazed plots also exhibited up to 34% lower light-use efficiency and a 2-week slower time to physiological maturation than soybeans in plots that had not been previously grazed. These results describe for the first time the differential crop growing conditions and crop physiological responses created after 16 years of integration with grazing animals. As integrated crop-livestock systems grow in importance in commercial production settings, this research can inform adaptive management practices to ensure the sustainability of these systems into the future and under a variety of environmental conditions.