Moderate Grazing Intensity Research Articles

Effects of the progressive abandonment of grazing on dung beetle biodiversity: body size matters

Dung beetles are an ecologically important group of insect species inhabiting semi-natural grasslands in Europe. Despite their ecological importance, several dung beetle species are currently facing local threats mainly stemming from changes in land use practices, including the abandonment of pasturelands. The aim of this study was to analyze the impact of the progressive abandonment of grazing lands on dung beetle alpha diversity, abundance, biomass and body size classes. Areas representing a range of trophic resource availability were compared: (i) abandoned, (ii) low and (iii) moderate grazing intensity. A total of 136,884 specimens belonging to 56 species (3 Geotrupinae; 16 Scarabaeinae; 37 Aphodiinae) of dung beetle were collected. Pastureland abandonment was shown to lead to a decrease in alpha diversity and biomass density, a reduction of 22 and 78% respectively in abandoned areas. From a biomass standpoint, the effects of pastureland abandonment varied according to the body size classes of the dung beetles, with larger species proving more susceptible to local extinction. Such body-size dependent variations led us to propose the use of both biomass and abundance data in making assessments since they are differentially sensitive to trophic resource availability. Hence, from a conservationist standpoint, the obtained results suggest that traditional pastureland management with low-moderate grazing intensity should be maintained.

Grazing intensity influence soil microbial communities and their implications for soil respiration

Abstract Soil microorganisms regulate carbon (C) transfer from terrestrial sources to the atmosphere, therefore playing a pivotal role in soil C dynamics. Worldwide, grazing is one of the most prevalent grassland management strategies, yet the effects of grazing on soil microbial community size and soil respiration (SR) are still active areas of debate. We conducted a meta-analysis of 71 publications to synthesize the responses of soil microbial community size and SR to grazing. Our results showed that grazing significantly decreased soil total microbial, bacterial and fungal community size by 11.74, 8.85 and 11.45%, respectively. However, this effect were differed when the studies were grouped by the grazing intensity. Briefly, light and moderate grazing intensity had no effect on soil microbial, bacterial and fungal community size, but heavy grazing intensity significantly reduced soil’s total microbial, bacterial and fungal community size by 14.79, 16.48 and 28.12%, respectively. The responses of microbial community size to grazing were positively correlated with those of SR both under moderate and heavy grazing intensity. Our findings indicate that soil microbial community size could be an important underlying mechanism involved in determining soil C dynamics under grazing. Hence better understanding of the responses of soil microbial community size would greatly contribute to our understanding of soil C dynamics. Lastly, our results underscore the importance of factoring grazing intensity into consideration to further improve the model’s projection of soil C dynamics.

Grazing Intensity and Phenotypic Plasticity in the Clonal Grass Leymus chinensis

Phenotypic plasticity enables plants to cope with changes in their environment. Plasticity in a population of Leymus chinensis, a common grass species in arid and semiarid temperate grasslands of northern China, was determined in a natural grassland grazed by large domestic herbivores. We measured shoot and bud characteristics monthly along a grazing intensity gradient indicated by distance from the village gate during two growing seasons. In addition, some plants along the gradient were removed to a common transplant garden and their growth was compared. Leaf characteristics (leaf angle, leaf length, and leaf number), growth form (tiller height and tiller clusters), bud proliferation, and plant fitness differed significantly in situ along the gradient. The expression of plasticity was grazing intensity dependent: the greatest increase in tiller density, tiller cluster, and bud number occurred at a moderate grazing intensity (2.5 km from the village gate). In the transplant garden, no evidence was found for distinct populations of L. chinensis within the grassland. Leaf characteristics, tiller growth form, and bud demography of tillers not grazed showed phenotypic plasticity in response to grazing of neighbor shoots because clonal reproduction is the main breeding system for this species in grazed natural grassland and defoliation of neighbor shoots is likely to affect the physiology and morphology of tillers that are not grazed. The observed overcompensation in vegetative reproduction may aid future survival and growth and could be achieved in a prudent grazing system designed to take into account the needs of this dominant grass in semiarid temperate steppes.

Soil carbon and nitrogen stocks, light organic matter, and remaining phosphorus under a crop-livestock integration system

Crop-livestock integration (CLI) is a management system that has been developed for a variety of soil and climatic conditions, which combined with the no-tillage system (NTS), has many variations in Brazil, particularly regarding grazing intensity. The objective of this study was to assess the effects of different grazing intensities and soybean (Glycine max L.) crops on carbon (Cst) and nitrogen (Nst) stocks, light organic matter (LOM), root content of the LOM (RLOM), and remaining phosphorus (Prem) in an Oxisol under CLI. The treatments consisted of three different heights (0.25 m [P25], 0.35 m [P35], and 0.45 m [P45]) of pasture grown in a CLI system. Two control areas, an area without grazing (AWG) and a native vegetation area of the Cerrado biome (NCA), which were adjacent to the experimental area, were compared with the cultivated areas. Soil samples were collected from 0.00-0.05, 0.05-0.10, and 0.10-0.20 m beneath each area in a completely randomized design with six replications. Soil characteristics were evaluated in the post-pasture cycle period (PP) and the post-soybean crop period (PC), which coincided with the wet and dry seasons, respectively. The NCA had more LOM in the 0.00-0.05 m layer during the PC and the 0.05-0.10 m layer during both the PP and the PC, C in the LOM in the 0.00-0.20 m layer during the PP and the PC, N in the LOM in the 0.00-0.05 m layer in the PC and the 0.05-0.10 m layer in the PP and the PC, and Cst in the 0.00-0.20 m layer in the PP and the PC than the cultivated areas, but a lower soil density (SD) and Prem in the 0.00-0.20 m layer during both the PP and the PC. Treatment P35 had more Nst in the PC and RLOM in the PP than the other cultivated treatments and the AWG. The absence of grazing in the AWG decreased the SD from the PP to the PC, while the treatments with different grazing intensities had similar values throughout this period. Our results suggest that production could be intensified under light and moderate grazing intensities in the CLI system.

Towards a mechanistic understanding of the effect that different species of large grazers have on grassland soil N availability

Abstract Herbivore grazing has major effects on soil nutrient dynamics in a variety of grassland ecosystems. Previous studies have examined how large herbivores as a group affect nutrient cycling, but little information is available on how assemblages of different herbivore species may influence nutrient cycling, and whether herbivore assemblage effects are influenced by plant community characteristics (e.g. composition, diversity) of the grazed grassland. We conducted a 5‐year, replicated grazing experiment to test the effects of different large herbivore assemblages (cattle grazing, sheep grazing, combined cattle and sheep grazing, no grazing) under moderate grazing intensity on soil nitrogen (N) mineralization rate in two types of grassland communities (high forbs/high diversity and low forbs/low diversity) in meadow steppe habitat of northeast China. Moreover, we examined two distinctly different pathways that herbivores could influence soil N availability: directly through urine and dung deposition and indirectly by shifting grassland species composition (i.e. the grass: forb ratio), thereby the quality of plant litter available to soil decomposers. We found that grazer effects on soil N availability (indexed with anion and cation adsorption strips) depended on herbivore assemblage, and the herbivore assemblage effects varied in the two types of grasslands. In one type of grassland characterized by low diversity, grazing by each of the herbivore assemblages enhanced soil N availability compared to the ungrazed plots, and mixed species (cattle and sheep) grazing had a greater effect than single species grazing. In high diversity grassland, single species herbivore grazing significantly increased soil N availability, but mixed grazing had no effect. Mixed linear modelling revealed that soil N availability was facilitated primarily by excreta additions to the soil and secondarily by the abundance of grasses. Synthesis. Grazers increased soil N availability directly by adding readily accessible N in urine and dung to the soil. Herbivores indirectly influenced soil N availability by altering the plant composition (grass: forb cover). Both mechanisms contributed to the variation in how different herbivore assemblages affected soil N availability in the two grassland types.

Impacts of grazing intensity and increased precipitation on a grasshopper assemblage (Orthoptera: Acrididae) in a meadow steppe

1. Grasshoppers are dominant herbivores in grassland ecosystems, and many studies have examined how grazing by large herbivores and precipitation patterns individually influence the dynamics of grassland grasshopper assemblages, but their combined effects are largely unknown.2. In this study, grazing intensities (ungrazed, moderate, and heavy) were manipulated and precipitation (ambient and increased amount of rainfall) altered in a field experiment to test the effects of grazing and altered precipitation on a grasshopper community in a meadow steppe in northeastern China.3. It was found that grasshopper species richness did not change according to different grazing intensities under ambient precipitation, but was significantly higher (by 38.1%) in moderate grazing intensities under increased precipitation. Grasshopper abundance increased considerably with increasing grazing intensities in ambient precipitation treatments; however, grasshopper abundance in heavy grazing intensities was significantly lower (by 32.9%) than in the other two grazing intensities under increased precipitation. Moreover, the responses of grasshopper abundance to grazing under altered precipitation were species‐specific.4. Grazing effects on grasshopper species diversity were mediated through the species richness and biomass of grasses (food resources), but the effects on grasshopper abundance were mediated through plant height (vegetation structure) under altered precipitation.5. These results suggest that appropriate grazing by large herbivores would be considered as beneficial management practices for maintaining grasshopper diversity and abundance under conditions of increased precipitation in grassland ecosystems. Additionally, greater attention should be paid to the population dynamics of different grasshopper species to better understand the responses of grasslands to grazing and altered precipitation.

Clonal integration increases tolerance of a phalanx clonal plant to defoliation

Defoliation by herbivores commonly imposes negative effects on plants, and physiological integration (resource sharing) can enhance the ability of guerilla clonal plants to tolerate stresses. Here we examined whether physiological integration can increase the ability of phalanx clonal plants to withstand defoliation. On a high mountain grassland in southwestern China, we subjected the phalanx clonal plant Iris delavayi within 10cm×10cm plots to three levels of defoliation intensity, i.e., control (no defoliation), moderate (50% shoot removal to simulate moderate herbivory) and heavy defoliation (100% shoot removal to simulate heavy herbivory), and kept rhizomes at the plot edges connected (allowing physiological integration) or disconnected (preventing integration) with intact ramets outside the plots. Defoliation significantly reduced leaf biomass, root biomass and ramet number of I. delavayi. Clonal integration did not affect the growth of I. delavayi under control, but significantly increased total biomass, rhizome and root biomass under heavy defoliation, and leaf biomass and ramet number under moderate defoliation. We conclude that clonal integration associated with resource reallocation plays an important role in maintaining the productivity of the alpine and subalpine grassland ecosystems in SW China where clonal plants are a dominant component of the grasslands and are commonly extensively managed with moderate grazing intensity. Our results also help to better understand the adaption and tolerance of phalanx clonal plants subjected to long-term grazing in the high mountain environment.

Effects of grazing intensity and the use of veterinary medical products on dung beetle biodiversity in the sub-mountainous landscape of Central Italy.

Grazing extensification and intensification are among the main problems affecting European grasslands. We analyze the impact of grazing intensity (low and moderate) and the use of veterinary medical products (VMPs) on the dung beetle community in the province of Pesaro-Urbino (Italy). Grazing intensity is a key factor in explaining the diversity of dung beetles. In the case of the alpha diversity component, sites with a low level of grazing activity—related in a previous step to the subsequent abandonment of traditional farming—is characterized by a loss of species richness (q = 0) and a reduction in alpha diversity at the levels q = 1 and q = 2. In the case of beta diversity, sites with a different grazing intensity show remarkable differences in terms of the composition of their species assemblages. The use of VMPs is another important factor in explaining changes in dung beetle diversity. In sites with a traditional use of VMPs, a significant loss of species richness and biomass is observed, as is a notable effect on beta diversity. In addition, the absence of indicator species in sites with a historical use of VMPs corroborates the hypothesis that these substances have a ubiquitous effect on dung beetles. However, the interaction between grazing activity and VMPs when it comes to explaining changes in dung beetle diversity is less significant (or is not significant) than the main effects (each factor separately) for alpha diversity, biomass and species composition. This may be explained if we consider that both factors affect the various species differently. In other words, the reduction in dung availability affects several larger species more than it does very small species, although this does not imply that the former are more susceptible to injury caused by the ingestion of dung contaminated with VMPs. Finally, in order to prevent negative consequences for dung beetle diversity, we propose the maintenance of a moderate grazing intensity and the rational use of VMPs. It is our view that organic management can prevent excessive extensification while providing an economic stimulus to the sector. Simultaneously, it can also prevent the abuse of VMPs.

Effects of grazing intensity on organic carbon stock characteristics in Stipa breviflora desert steppe vegetation soil systems

Grassland ecosystems, an important component of the terrestrial environment, play an essential role in the global carbon cycle and balance. We considered four different grazing intensities on a Stipa breviflora desert steppe: heavy grazing (HG), moderate grazing (MG), light grazing (LG), and an area fenced to exclude livestock grazing as the Control (CK). The analyses of the aboveground biomass, litter, belowground biomass, soil organic carbon and soil light fraction organic carbon were utilised to study the organic carbon stock characteristics in the S. breviflora desert steppe under different grazing intensities. This is important to reveal the mechanisms of grazing impact on carbon processes in the desert steppe, and can provide a theoretical basis for conservation and utilisation of grassland resources. Results showed that the carbon stock was 11.98–44.51 g m–2 in aboveground biomass, 10.43–36.12 g m–2 in plant litters, and 502.30–804.31 g m–2 in belowground biomass (0–40 cm). It was significantly higher in CK than in MG and HG. The carbon stock at 0–40-cm soil depth was 7817.43–9694.16 g m–2, and it was significantly higher in LG than in CK and HG. The total carbon stock in the vegetation-soil system was 8342.14–10494.80 g m–2 under different grazing intensities, with the largest value in LG, followed by MG, CK, and HG. About 90.54–93.71% of the total carbon in grassland ecosystem was reserved in soil. The LG and MG intensities were beneficial to the accumulation of soil organic carbon stock. The soil light fraction organic carbon stock was 484.20–654.62 g m–2 and was the highest under LG intensity. The LG and MG intensities were beneficial for soil nutrient accumulation in the desert steppe.

Variation in biomass and morphology of Artemisia fragrans Willd. under grazing in northwest mountainous rangelands of Iran

Animal grazing in rangelands ecosystems is considered as one of the most influential factors in changing plants' biomass, dimensional characteristics and different aspects of ecosystem. Regarding the fact that Artemisia fragrans species is one of the main dominated species of mountainous rangelands in the northwest of Iran, limited information is available concerning the influence of various grazing intensities on its structural properties, aerial biomass, and especially on its underground biomass. In order to this, the effects of different grazing intensities (low, moderate and high) on aerial and underground biomass and structural properties of this species are investigated. Accordingly, three rangeland areas with various grazing intensities were chosen and sixty 1m2 plots were established along six, 100m transects. Afterwards, structural properties, leaf litter, aerial and underground biomass of the Artemisia fragrans species were measured in each of the areas. In order to compare the mean biomass and structural parameters of the plant in the three areas, one-way ANOVA and Duncan's multiple range tests were used. The results indicate that there is a significant difference between the quantity of investigated parameters (except for the area and diameter of the collar) of the studied species under three grazing intensities. The highest and lowest aerial biomass average in two places with low and high grazing intensities was 5.18 and 76.42g, respectively. Moreover, the maximum average of underground biomass per plant (95.32g) and its minimum amount (46.56g) belong to low and high grazing intensities, respectively. Estimating the percentage of parameters' variations in areas with high and moderate grazing intensities in comparison to the area with low grazing intensity demonstrated that all the parameters had a decreasing trend and the maximum percentage of variations of this species is related to the high intensity grazing area. Generally, by increasing grazing intensity, the decrease in collar diameter and plant cover was the lowest and for the characteristics of leaf litter, underground and aerial biomass was the highest.

Patterns and thresholds of grazing‐induced changes in community structure and ecosystem functioning: species‐level responses and the critical role of species traits

Summary Overgrazing has resulted in widespread decline in biodiversity and ecosystem functioning in grasslands world‐wide in recent decades. However, few studies have examined the patterns and thresholds of grazing‐induced changes in community structure and ecosystem functioning along a grazing gradient and based on species‐level responses and plant functional traits. To identify the thresholds of grazing intensity (GI) at both species and community levels, we conducted a grazing manipulation experiment with seven levels of GI (0–9 sheep ha−1) and two topographies (flat vs. slope) in a typical steppe. Four plant functional traits were measured, including specific leaf area (SLA), plant height, leaf nitrogen content (LNC) and stem: leaf ratio. The threshold of GI that significantly altered community composition was at 3·75 sheep ha−1 for the flat system and 3·0 sheep ha−1 for the slope system. For both flat and slope systems, the threshold GI for changes in primary productivity was at 3·0 sheep ha−1, beyond which the productivity decreased substantially. At the species level, the abundances of common species, most of which are perennial grasses, declined at moderate grazing intensities (3·0–4·5 sheep ha−1). The abundances of most rare species, which are perennial forbs, declined at low grazing intensities (1·5–3·0 sheep ha−1). SLA and LNC are good predictors of species‐level responses to grazing. Low SLA and high LNC species are negatively affected by high GI, while high SLA and low LNC species are little affected by grazing. The negative effect of GI on species’ abundance was greater in the slope system than in the flat system. Synthesis and applications. Our results indicate that the structural and functioning thresholds of grazing intensity depend on plant traits and species composition, which is mediated by topographic location. These findings, integrating plant functional traits and threshold approaches, have important implications for determining sustainable grazing intensity in grassland management and biodiversity conservation in semi‐arid regions.

Maintain Spatial Heterogeneity, Maintain Biodiversity—A Seed Bank Study in a Grazed Alpine Fen Meadow

AbstractWetland degradation is a source of anxiety and is more severe in cold regions than other areas. The soil seed bank acts as a propagule source for revegetation to affiliate the restoration of degraded wetlands. However, the effects of this approach are controversial and depend on the traits of the seed bank and its interactions with the environment. The seed bank in an alpine fen meadow was studied to determine its exact role in revegetation. The surveyed shore of a Tibetan lake, Gahai Lake, was divided into three sites under different levels of grazing pressure. Each site was separated into six transects along a water‐depth gradient to collect soil cores to determine the pattern of biodiversity through a germination experiment in a greenhouse. After an analysis of heterogeneity‐related diversity, partitioning of 58 discovered species indicated that 39.5 could be contributed to beta‐diversity, which was mainly contributed to water depth. Overgrazing (0.607 sheep unit/acre, November—March) decreased seed bank diversity in many respects, especially through decreasing spatial heterogeneity and homogenizing biota. A lightly grazed, well‐protected site had not only the highest beta‐diversity and species abundance but also the highest inter‐site species turnover rate compared with other sites under moderate grazing intensity. Despite the lack of target species, the seed bank serves as (i) a species‐rich pool; (ii) an extant legacy seed source for sustaining heterogeneity and floristic diversity; and (iii) an ecological indicator, and its effect can be reinforced by appropriate grazing practices (multiple intensity) and hydrological modifications. Copyright © 2016 John Wiley & Sons, Ltd.

Cattle Grazing Intensity and Duration Have Varied Effects on Songbird Nest Survival in Mixed-Grass Prairies

Grassland bird species are declining more quickly than birds of any other biome in North America, but effects of the most widespread use of native mixed-grass prairies, livestock grazing, on nest survival of songbirds are not well understood. We used an adaptive management grazing experiment in southwestern Saskatchewan to evaluate effects of cattle grazing intensity and number of years grazed on nest survival of five songbird species in 2009 and 2010. Two 300-m² plots were located in each of 12 pastures. Three pastures were ungrazed controls, while the remaining pastures had grazing intensities ranging from 0.23 to 0.83 animal unit months (AUM) · ha−1 (very low to very high for this region) and were grazed for 2−3 or > 15 yr. Analyses were conducted using logistic exposure regression. We found few effects of grazing on nest survival. Exceptions to this pattern were that the lowest nest survival rates occurred at low-moderate grazing intensities for Sprague’s pipits (Anthus spragueii) in 2009, at low grazing intensities for chestnut-collared longspurs (Calcarius ornatus) in 2009, and at moderate grazing intensities for vesper sparrows (Pooecetes gramineus) in 2010. Increasing grazing duration lowered nest survival for Sprague’s pipits and increased nest survival for chestnut-collared longspurs in 2009. Although low or moderate grazing intensities are generally recommended to promote wildlife conservation, this may not promote productivity of all species. Nonetheless, our results suggest that in the short term, a wide range of grazing intensities is consistent with conservation of grassland songbirds.

Temporal profiles of vegetation indices for characterizing grazing intensity on natural grasslands in Pampa biome

The Pampa biome is an important ecosystem in Brazil that is highly relevant to livestock production. The objective of this study was to analyze the potential use of vegetation indices to discriminate grazing intensities on natural grasslands in the Pampa biome. Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) images from Jan to Dec, 2000 to 2013 series, were analyzed for natural grassland experimental units managed under high (forage allowance of 5 ± 2 % live weight – LW), moderate (13 ± 5 % LW) and low grazing intensity (19 ± 7 % LW). Regardless of intensity, the temporal profiles showed lower NDVI and EVI during winter, increased values in spring because of summer species regrowth, slightly decreased values in summer, especially in years when there is a water deficit, and increased values in the fall associated with the beginning of winter forage development. The average temporal profiles of moderate grazing intensity exhibited greater vegetation index values compared with low and high grazing intensities. The temporal profiles of less vegetation index were associated with lower green biomass accumulation caused by the negative impact of stocking rates on the leaf area index under high grazing intensity and a floristic composition with a predominance of tussocks under low grazing intensity. Vegetation indices can be used for distinguishing moderate grazing intensity from low and high intensities. The average EVI values can discriminate moderate grazing intensity during any season, and the NDVI values can discriminate moderate grazing intensity during spring and winter.

Importance of Early Season Conditions and Grazing on Carbon Dioxide Fluxes in Colorado Shortgrass Steppe

Understanding the influence of grazing management and environmental drivers on net ecosystem exchange of CO2 (NEE) is essential for optimizing carbon (C) uptake in rangelands. Herein, using 15 treatment-years (two 3-yr experiments, one with three grazing treatments, the other two) and Bowen ratio flux towers, we evaluated the influence of grazing intensity, soil water content (SWC), and plant cover (Normalized Difference Vegetation Index, or NDVI) on NEE in Colorado shortgrass steppe. Among several soil water and plant cover traits evaluated over 6-yr, early season (April, DOY 91–120) SWC and early season (DOY 130) NDVI were most highly correlated with NEE (−0.96 and −0.98, respectively) during the second quarter (April to June) of the year and also over the entire growing season (April to September; −0.97 and −0.96). Due to the strong effect of early-season SWC, an average of 166 g m−2 CO2 were lost in 2 yr with dry spring weather, compared with an average annual uptake of 218 g m−2 CO2 in 4 yr with more abundant early-season precipitation and plant cover. Grazing effects on NEE were also apparent. In one experiment, moderate grazing resulted in annual CO2 uptake of 267 g m−2 CO2 over 3 yr compared with essentially zero NEE in heavily grazed pasture. However, that treatment difference in annual NEE was only half that experienced between dry and wet years. Similar trends were observed in a second experiment, although results were insignificant. Results suggest that the recommended moderate grazing intensity for the Colorado shortgrass steppe is near optimal for CO2 uptake under season-long continuous grazing, with annual climatic variability sometimes being more influential. To enhance C sequestration in the western Great Plains of North America, grazing management strategies should emphasize flexible and adaptive practices that consider early-season SWC and promote vegetation cover during the key early spring growth period.

Elk Foraging Site Selection on Foothill and Mountain Rangeland in Spring

Previous research suggests facilitative grazing by cattle during the preceding summer-fall can enhance spring foraging habitat of Rocky Mountain elk (Cervus elaphus nelsoni). However, previous studies were limited to 1 year or conducted within relatively small experimental pastures. We evaluated elk foraging site selection during spring across 4 years and 59 040 ha of foothill and mountain rangeland in northwestern Wyoming and west-central Montana. Elk in spring avoided foraging in nonforested portions of cattle-grazed pastures where cattle had not grazed during the previous summer−early fall. In contrast, elk selected foraging sites where cattle had grazed lightly (11−30% forage use) or moderately (31−60% forage use), and selection by elk was stronger for moderately grazed sites. Neither moderate nor light cattle grazing intensity were correlated with any other elk habitat attribute that we sampled, and both moderate and light cattle grazing intensity exerted more influence on elk foraging site selection than any other variables, including distance to security cover, distance to primitive roads, distance to improved roads, aspect, or slope. We developed and validated a resource selection model that correctly classified 80−89% of elk foraging observations across five study sites and 4 years. Resource managers can use our model to map predicted changes in elk grazing distribution when considering potential habitat adjustments in security cover, roads, or cattle grazing intensities and distribution. Our results indicate that resource managers can use targeted cattle grazing in summer−early fall to purposely modify elk forage conditions to 1) increase elk foraging efficiency in spring, 2) lure elk away from places needing rest or deferment from spring elk grazing, or 3) lure elk away from places where elk in spring are experiencing conflicts with humans, predators, or other wildlife.

Soil phosphorus compounds in integrated crop-livestock systems of subtropical Brazil

Soil phosphorus (P) utilization may be affected by agricultural complexity, in particular when combining annual crops and livestock grazing on the same land area and at overlapping times. Our objectives were to qualify and quantify soil organic and inorganic P compounds using sodium hydroxide-ethylenediaminetetraacetic acid (NaOH-EDTA) extraction and 31P nuclear magnetic resonance spectroscopy (31P NMR) in response to increasing complexity with integrated crop-livestock systems (ICLS) in subtropical Brazil. Soil at a depth of 0–5cm was collected from three long-term (7 to 12years) cropping studies with and without ruminant grazing of cover crops. All sites were managed under no tillage, and treatments with livestock were managed with moderate grazing intensity. In these agro-ecosystems, grazing compared with no-grazing had greater soil P content as total and bioavailable orthophosphate and lower soil organic P and fewer monoesters, including inositol phosphates. Grazing increased P bioavailability and reduced recalcitrant organic P concentration in soil; therefore, cropping systems that integrate livestock (ICLS) can be a sustainable alternative to improve P use in farming systems of subtropical Brazil.

Small‐scale Geodiversity Regulates Functioning, Connectivity, and Productivity of Shrubby, Semi‐arid Rangelands

AbstractGeodiversity has recently been attracting increasing attention as a measure of diversity for the physical components of natural environments. It has shown positive relations with biodiversity, as well as with several ecosystem services. Yet, so far, geodiversity studies have focused on relatively large spatial scales, ranging between hillslope, basin, and landform scales. It is proposed that either natural‐induced or anthropogenic‐induced, small‐scale (centimeter‐scale to few decimeter‐scale) geodiversity has a large impact on the hydrological connectivity and overall functioning of semi‐arid rangelands and other shrubby and woody drylands. It is further proposed that greater small‐scale geodiversity increases the on‐site retention of water and soil resources, decreasing the vulnerability of rangelands to prolonged droughts and climatic changes. Particularly, positive impact of moderate grazing intensity on rangelands functioning is demonstrated by the formation of livestock trampling routes, which transect hillslopes, increase ecosystem geodiversity, and modify the spatial redistribution of scarce water and soil resources at the patch scale. Numerical simulations of a mathematical model for vegetation patterns in water‐limited systems show that the trampling routes increase the survivability of vegetation patches under prolonged droughts. In practical terms, the concept of small‐scale geodiversity is relevant for the determination, monitoring, and assessment of land degradation, as well as for restoration projects of eroded lands and degraded ecosystems. Copyright © 2015 John Wiley & Sons, Ltd.

Restoring sand shinnery oak prairies with herbicide and grazing in New Mexico

Abstract Sand shinnery oak (Quercus havardii) prairies are increasingly disappearing and increasingly degraded in the Southern High Plains of Texas and New Mexico. Restoring and managing sand shinnery oak prairie can support biodiversity, specific species of conservation concern, and livestock production. We measured vegetation response to four treatment combinations of herbicide (tebuthiuron applied at 0.60 kg/ha) and moderate-intensity grazing (50% removal of annual herbaceous production) over a 10-year period in a sand shinnery oak prairie of eastern New Mexico. We compared the annual vegetation response to the historical climax plant community (HCPC) as outlined by the U.S. Department of Agriculture Ecological Site Description. From 2 to 10 years postapplication, tebuthiuron-treated plots had reduced shrub cover with twice as much forb and grass cover as untreated plots. Tebuthiuron-treated plots, regardless of the presence of grazing, most frequently met HCPC. Tebuthiuron and moderate-intensity grazi...

Sheep grazing and soil bacterial diversity in shrublands of the Patagonian Monte, Argentina

Our objective was to assess whether long-term continuous sheep grazing was associated with the bacterial community of the Patagonian Monte soils. We randomly extracted soil samples from 5 plant-covered patches (PCP) and the nearest inter-canopy areas (IC) at sites with low (L), moderate (M) and heavy (H) grazing intensity. Bacterial communities were evaluated by denaturing gradient gel electrophoresis (DGGE) and dominant bands were sequenced. Dendrograms showed a different association among grazing sites in PCP compared to IC areas. In PCP, M and H sites were clustered and DGGE revealed a high similarity in the bacterial community regardless of grazing intensity. In IC areas, analyses clustered L and M sites. Band sequencing revealed that members of these communities belonged to Sphingobacteria, Solibacteres, Gammaproteobacteria, Betaproteobacteria and Bacilli. Some of the band sequences related to Nitrosococcus oceani and Nitrosococcus watsonii which are restricted to marine environments and salt lakes. Microcoleus vaginatus and diatom chloroplast-related sequences were mainly detected in IC areas from L and M. Heavy grazing could alter autotrophic bacteria/diatom composition in IC areas possibly due to physical disturbance of biological crusts by trampling, threatening the potential of crust re-formation. Grazing intensity affected soil bacterial communities differently in PCP and IC areas with soil crust, highlighting the importance of improving our understanding of microbial diversity responses to land use.