INFILTRATION AND WATER QUALITY ON RANGE SITES AT FORT STANTON,NEW MEXICO1

ABSTRACT: The hydrologic impacts of livestock grazing schemes on selected plant communities and soils at Fort Stanton, New Mexico, were evaluated. Simulated rainfall was applied to 1 m²plots. On a mesa-top, infiltration rates for a grassland livestock exclosure and a pinyon pine-juniper community closely approximated each other and were significantly greater (P = 0.10) than either a moderate continuous or a heavy continuous treatment in a grassland community. Sediment concentration from the heavy continuous treatment was more than twice that of the other treatments. Infiltration rates on the hillside site were highest in a pinyon pine-juniper community receiving short duration grazing. Infiltration for this treatment was found to be significantly higher (P = 0.10) than that of a short duration grazing treatment, but not from a rest rotation grazing treatment on grassland. The short duration grazing treatment on a grassland had the highest sediment concentration, while the rest rotation grazing on a grassland and the short duration pinyon pine-juniper treatments were found to be similar. In the bottomland site, a fertilized and unfertilized treatment showed no significant difference in infiltration or sediment concentration, although twice as many animals were present on the fertilized treatment.     

Effect of grazing on plant attributes and hydrological properties in the sloping lands of the East African highlands

Extending livestock grazing to the steep slopes has led to unstable grazing systems in the East African Highlands, and new solutions and approaches are needed to ameliorate the current situation. This work was aimed at studying the effect of livestock grazing on plant attributes and hydrological properties. The study was conducted from 1996 to 2000 at the International Livestock Research Institute at Debre Ziet Research Station. Two sites were selected: one at 0–4% slope, and the other at 4–8% slope. The treatments were: (1) no grazing (control); (2) light grazing, 0.6 animal unit months per hectare (aum/ha); (3) moderate grazing, 1.8 aum/ha; (4) heavy grazing, 3.0 aum/ha; (5) very heavy grazing, 4.2 aum/ha; (6) initially plowed and continuously very heavily grazed, 4.2 aum/ha. The result showed that species richness, infiltration rate, bare ground, and soil loss significantly varied with grazing pressure. Species richness was higher in grazed plots compared to nongrazed plots. Biomass yield improved on heavily grazed plots as cow dung accumulated over years. Cynodon dactylon plant species persisted with livestock grazing pressure in both sites. Infiltration rate improved and soil erosion declined in all treatments after the first year.     

Impact of Grazing on Plant Species Richness, Plant Biomass, Plant Attribute, and Soil Physical and Hydrological Properties of Vertisol in East African Highlands

Understanding the problems of grazing land in vertisol areas and seeking long-lasting solutions is the central point where mixed crop livestock is the second stay for the majority of the population. In order to understand this, the current study was conducted at two sites, one with 0–4% slope and the other with 4–8% slope at Ginchi watershed, 80 km west of Addis Ababa, Ethiopia. The specific objectives of the study were to quantify changes in plant species richness, biomass, plant cover, and soil physical and hydrological properties. The grazing regimes were: moderate grazing (regulated), heavy grazing (free grazing), and no grazing (closed to any grazing), which was considered the control treatment. The results showed that the biomass yield in nongrazed plots was higher than in the grazed plots. However, the biomass yield in grazed plots improved over the years. Species richness and percentage of dominant species attributes were better in medium grazed plots than the other treatments. Soil compaction was higher in very heavily grazed plots than in nongrazed and medium-grazed plots. In contrast to that, the soil water content and infiltration rate were better in nongrazed plots than in grazed plots. Soil loss in grazed plots decreased with the increase of biomass yields and as the soil was more compacted by livestock trampling during the wet season. Finally since the medium stocking rate is better in species richness and plant attributes, and lies between nongrazed and heavily grazed plots in the rest of the measured parameters, it could be the appropriate stocking rate to practice by the smallholder farmer.     

RUNOFF AND SEDIMENT YIELD UNDER GRAZING IN FOOTHILLS FESCUE GRASSLANDS OF ALBERTA1

ABSTRACT: Grazing can have a profound impact on infiltration and thus runoff and erosion. The objectives of this study were to quantify the effects of select grazing systems on rainfall and snowmelt induced runoff and sediment yield from sloped areas of the foothills fescue grasslands of Alberta, Canada. The effects of two grazing intensities (heavy and very heavy) for two durations (short duration and continuous throughout the growing season) were compared to an ungrazed control between June 1988 and April 1991. Runoff was measured using 1-rn² runoff frames and collection bucket systems. Sediment yields were then determined on samples from the collected runoff. Snowmelt was the dominant source of runoff. Snowmelt runoff was higher from the heavily grazed areas than from the very heavily grazed areas, due to the higher standing vegetation which accumulated snow in the former areas. Sediment yields as a result of snowmelt were generally low in all areas. Only a few summer storms caused runoff. Runoff volumes and sediment yields from summer rainstorms were low, due to low rainfall and to generally dry antecedent soil moisture conditions. The greatest risk of summer runoff, and thus sediment yield, appears to occur in August.     

The Effects of Long Time Conservation of Heavily Grazed Shrubland: A Case Study in the Northern Negev,Israel

One of the major reasons for desertification is unrestricted grazing leading to vegetation depletion, soil erosion and degradation, phenomena often considered irreversible in the short term. Here, we compare soil and biological parameters of degraded and conserved, recently rehabilitated arid shrubland in the Northern Negev, Israel. The study area was restored by conservation efforts including a strictly controlled grazing regime initiated in 1992. The visually recognizable improvement in the ecology of the restored shrubland is reflected in significant improvement in all examined biotic (herbaceous biomass, shrub patch density, and insect activity), and soil parameters (nutrients, organic matter content, moisture, and water infiltration). The difference is created predominantly by restoration of large biological patches composed of shrubs and other perennial plants often associated with ant or termite nests, where the most significant increases in productivity and soil quality were observed. In the conserved shrubland such patches covered 35 or 25 % of the area (in a normal and a drought year, respectively). In the degraded shrubland 5 % or less of the area was occupied by such patches that were much smaller and of lower biological complexity. With respect to plant biodiversity, six plant species were found only—and 18 others became significantly more common—in the rehabilitated area. The results of this article indicate that functional arid drylands can be restored within <16 years relying on strict conservation management with reduced grazing intensity.     

Using Social Media to Discover Public Values, Interests, and Perceptions about Cattle Grazing on Park Lands

In the western United States, livestock grazing often co-exists with recreation, cultural resource management and biodiversity protection on federal and state protected rangelands as well as on many local government open space areas. While the value of livestock grazing for managing rangeland vegetation to reduce fire fuel loads and improve wildlife habitat is increasingly recognized by resource management professionals, public concerns, and conflict between recreationist and livestock have led to reductions in public land grazing. Traditional public input methods yield a constrained picture of people’s attitudes toward cows and public land grazing. Public meetings, hearings, and surveys, the most commonly used mechanisms for public land managers to solicit public opinion, tend to foster participation of organized special interests or, in the case of surveys, focus on a specific topic. General public input is limited. This study explored the use of personal photography in social media to gain insight into public perceptions of livestock grazing in public spaces. Key findings of this study include that many recreationist in grazed San Francisco Bay Area parks shared views, interests, and concerns about cows and grazing on the photo-sharing website, Flickr^TM that seldom show up at a public meeting or in surveys. Results suggest that social media analysis can help develop a more nuanced understanding of public viewpoints useful in making decisions and creating outreach and education programs for public grazing lands. This study demonstrates that using such media can be useful in gaining an understanding of public concerns about natural resource management.     

Western Land Managers will Need all Available Tools for Adapting to Climate Change,Including Grazing: A Critique of Beschta et al.

In a previous article, Beschta et al. (Environ Manag 51(2):474–491, 2013) argue that grazing by large ungulates (both native and domestic) should be eliminated or greatly reduced on western public lands to reduce potential climate change impacts. The authors did not present a balanced synthesis of the scientific literature, and their publication is more of an opinion article. Their conclusions do not reflect the complexities associated with herbivore grazing. Because grazing is a complex ecological process, synthesis of the scientific literature can be a challenge. Legacy effects of uncontrolled grazing during the homestead era further complicate analysis of current grazing impacts. Interactions of climate change and grazing will depend on the specific situation. For example, increasing atmospheric CO₂ and temperatures may increase accumulation of fine fuels (primarily grasses) and thus increase wildfire risk. Prescribed grazing by livestock is one of the few management tools available for reducing fine fuel accumulation. While there are certainly points on the landscape where herbivore impacts can be identified, there are also vast grazed areas where impacts are minimal. Broad scale reduction of domestic and wild herbivores to help native plant communities cope with climate change will be unnecessary because over the past 20–50 years land managers have actively sought to bring populations of native and domestic herbivores in balance with the potential of vegetation and soils. To cope with a changing climate, land managers will need access to all available vegetation management tools, including grazing.     

Methane emissions of beef cattle on forages: efficiency of grazing management systems

Fermentation in the rumen of cattle produces methane (CH4). Methane may play a role in global warming scenarios. The linking of grazing management strategies to more efficient beef production while reducing the CH4 emitted by beef cattle is important. The sulfur hexafluoride (SF6) tracer technique was used to determine the effects of best management practices (BMP) grazing compared with continuous grazing on CH4 production in several Louisiana forages during 1996-1998. Cows and heifers (Bos taurus) grazed common bermudagrass [Cynodon dactylon (L.) Pers.], bahiagrass (Paspalum notatum Flugge), and ryegrass (Lolium multiflorum Lam.) pastures and were wintered on bahiagrass hay with supplements of protein molasses blocks (PMB), cottonseed meal and corn (CSMC), urea and corn (URC), or limited ryegrass grazing (LRG). Daily CH4 emissions were between 89 and 180 g d(-1) for young growing heifers and 165 to 294 g d(-1) for mature Simbrah cows. Heifers on "ad lib" ryegrass in March and April produced only one-tenth the CH4 per kg of gain as heifers on LRG of 1 h. Using BMP significantly reduced the emission of CH4 per unit of animal weight gain. Management-intensive grazing (MIG) is a BMP that offers the potential for more efficient utilization of grazed forage crops via controlled rotational grazing and more efficient conversion of forage into meat and milk. Projected CH4 annual emissions in cows reflect a 22% reduction from BMP when compared with continuous grazing in this study. With the BMP application of MIG, less methane was produced per kilogram of beef gain.     

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Grazing management necessarily emphasizes the most spatially extensive vegetation assemblages, but landscapes are mosaics, often with more mesic vegetation types embedded within a matrix of drier vegetation. Our primary objective was to contrast effects of equine grazing on both subalpine vegetation structure and associated arthropods in a drier reed grass (Calamagrostis muiriana) dominated habitat versus a wetter, more productive sedge habitat (Carex utriculata). A second objective was to compare reed grass and sedge as habitats for fauna, irrespective of grazing. All work was done in Sequoia National Park (CA, USA), where detailed, long-term records of stock management were available. We sampled paired grazed and control wet meadows that contained both habitats. There were moderate negative effects of grazing on vegetation, and effects were greater in sedge than in reed grass. Conversely, negative grazing effects on arthropods, albeit limited, were greater in the drier reed grass, possibly due to microhabitat differences. The differing effects on plants and animals as a function of habitat emphasize the importance of considering both flora and fauna, as well as multiple habitat types, when making management decisions. Sedge supported twice the overall arthropod abundance of reed grass as well as greater diversity; hemipteran and dipteran taxa were particularly abundant in sedge. Given the greater grazing effects on sedge vegetation, greater habitat provision for terrestrial arthropods, and value as aquatic arthropod habitat, the wetter sedge assemblage is worthy of additional consideration by managers when planning for grazing and other aspects of land usage.     

Grazed Riparian Management and Stream Channel Response in Southeastern Minnesota (USA) Streams

The U.S. Department of Agriculture-Natural Resources Conservation Service has recommended domestic cattle grazing exclusion from riparian corridors for decades. This recommendation was based on a belief that domestic cattle grazing would typically destroy stream bank vegetation and in-channel habitat. Continuous grazing (CG) has caused adverse environmental damage, but along cohesive-sediment stream banks of disturbed catchments in southeastern Minnesota, short-duration grazing (SDG), a rotational grazing system, may offer a better riparian management practice than CG. Over 30 physical and biological metrics were gathered at 26 sites to evaluate differences between SDG, CG, and nongrazed sites (NG). Ordinations produced with nonmetric multidimensional scaling (NMS) indicated a gradient with a benthic macroinvertebrate index of biotic integrity (IBI) and riparian site management; low IBI scores associated with CG sites and higher IBI scores associated with NG sites. Nongrazed sites were associated with reduced soil compaction and higher bank stability, as measured by the Pfankuch stability index; whereas CG sites were associated with increased soil compaction and lower bank stability, SDG sites were intermediate. Bedrock geology influenced NMS results: sites with carbonate derived cobble were associated with more stable channels and higher IBI scores. Though current riparian grazing practices in southeastern Minnesota present pollution problems, short duration grazing could reduce sediment pollution if managed in an environmentally sustainable fashion that considers stream channel response.     

Sheep grazing effects on Mojave Desert vegetation and soils

Some effects of domestic sheep grazing on vegetation and soils were measured at four sites in the western Mojave Desert. Although sheep have grazed the Mojave Desert for the past 50–100 years, the effects of grazing on the desert ecosystem are largely unknown.The results reflect only short-term effects of grazing, because fenced control areas were not available for study. Heavy grazing caused a 60% reduction in the above-ground biomass under creosote bushes (Larrea tridentata), and sheep trampling caused an increase in soil strength and decreased intershrub annual densities 24 and 28% in two areas. The average area per individual (cover) of burrobush (Ambrosia dumosa) decreased 16–19% and the cover of spiny hop-sage (Grayia spinosa) decreased 29% under grazing pressure. The volumes of individual Ambrosia were 21 and 65% less in two heavily grazed areas than in two lightly grazed areas; the volume of goldenhead (Acamptopappus sphaerocephalus) was 68% less in one heavily grazed area.These changes indicate that the range quality of the Mojave Desert is deteriorating under sheep grazing pressures. Trampling reduces annual cover and disrupts the soil surface, thus promoting wind erosion. The loss of annual biomass and shrub cover should adversely affect reptiles and rodents by removing food sources and protection. Soil strength increases may retard future growth of annuals, further contributing to erosion and food source losses. Studies should be initiated to determine the long-term effects of grazing in the Mojave Desert.     

Reducing Livestock Effects on Public Lands in the Western United States as the Climate Changes: A Reply to Svejcar et al

Svejcar et al. (Environ Manage, 2014) offered several perspectives regarding Beschta et al. (Environ Manage 51:474–491, 2013)—a publication that addressed the interacting ecological effects of climate change and domestic, wild, and feral ungulates on public lands in the western United States (US)—by largely focusing on three livestock grazing issues: (1) legacy versus current day impacts; (2) grazing as a fire reduction tool; and (3) the complexity of grazing. Regarding these issues, we indicate that (1) legacy effects to western ecosystems were indeed significant and contemporary livestock use on public lands generally maintains or exacerbates many of those effects; (2) livestock grazing has been a major factor affecting fire frequency, fire severity, and ecosystem trajectories in the western US for over a century; and (3) the removal or reduction of grazing impacts in these altered ecosystems is the most effective means of initiating ecological recovery. Svejcar et al. (Environ Manage, 2014) offer no evidence that livestock use is consistent with the timely recovery of grazing-degraded uplands, riparian areas, or stream systems. We thus conclude that public-land ecosystems can best persist or cope with a changing climate by significantly reducing ungulate grazing and related impacts.     

Plant and soil surface responses to a combination of shrub removal and grazing in a shrub-encroached woodland

Shrub encroachment into open woodland is a widespread phenomenon in semi-arid woodlands worldwide. Encroachment or woody thickening, is thought to result from overgrazing, changes in fire regimes and increased atmospheric carbon dioxide concentrations. Eighteen years after one-off shrub removal by ploughing we assessed the effects of four different land management systems resulting from two levels each of grazing (grazed, ungrazed) with and without ploughing, on the cover of landscape units, soil surface condition, diversity of understorey plants and density of shrubs. We recorded 2–7 times more patches under conventional conservation (unploughed-ungrazed) than the others treatments, and plant cover and diversity were greater on the two conservation (ungrazed) plots, irrespective of ploughing. Soils under shrubs and log mounds had greater indices of infiltration, stability and nutrients. Shrub density under the active pastoral (ploughed-grazed) treatment was two and a half times greater than that in other treatments, but results were not significant. The effects of different treatments on shrubs were largely species-specific. Overall, our results suggest that ploughing does not provide long-term control of encroaching shrubs.     

The Effects of Long-Term Grazing Exclosures on Range Plants in the Central Anatolian Region of Turkey

Over the last fifty years, almost half of the steppe rangeland in the Central Anatolian Region of Turkey (CAR) has been converted to cropland without an equivalent reduction in grazing animals. This shift has led to heavy grazing pressure on rangeland vegetation. A study was initiated in June 2003 using 6 multiscale Modified-Whittaker plots to determine differences in plant composition between areas that have not been grazed in 27 years with neighboring grazed plant communities. A total of 113 plant species were identified in the study area with the ungrazed plots containing 32 plants more than the grazed plots. The major species were Astragalus acicularis, Bromus tomentellus, Festuca valesiaca, Genista albida, Globularia orientalis, Poa bulbosa, and Thymus spyleus ssp rosulans. Grazing impacts on forbs were more pronounced than for grasses and shrubs. Based on Jaccard’s index, there was only a 37% similarity of plant species between the two treatments. Our study led to four generalizations about the current grazing regime and long-term exclosures in the steppe rangeland around the study area: (1) exclosures will increase species richness, (2) heavy grazing may have removed some plant species, (3) complete protection from grazing for a prolonged period of time after a long history of grazing disturbance may not lead to an increase in desirable plant species with a concomitant improvement in range condition, and (4) research needs to be conducted to determine how these rangelands can be improved.     

Consequences of Livestock Grazing on Water Quality and Benthic Algal Biomass in a Canadian Natural Grassland Plateau

The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau, Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early season livestock grazing (June–August), (2) late season livestock grazing (August–September), (3) all season grazing (June–September), and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation, and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments. Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons) were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable, and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO₂ ^? + NO₃ ^? and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal communities were either nitrogen-limited or not limited by nutrients, depending on stream and season.     

Heterogeneity of Thermal Extremes: Driven by Disturbance or Inherent in the Landscape

Ecologists are beginning to recognize the effect of heterogeneity on structure and function in arid and semiarid ecosystems. Additionally, the influences of temperature on ecosystems are widely documented, but landscape temperature patterns and relationships with vegetation are rarely reported in ecological studies. To better understand the importance of temperature patterns to the conservation and restoration of native ecosystems, we designed an experiment to investigate relationships among soil surface temperature, landscape heterogeneity, and grazing intensity. Grazing intensity did influence the vegetation structure and composition. Heavy treatments had the greatest bare ground and the least vertical structure. Ungrazed treatments had the most litter and live grass cover. However, average temperatures among the three grazing treatments were not different and ranged less than 2°C during midday summer periods. The temperature difference between riparian and upland landscapes within grazing treatments was 21°C. Landscape position (riparian vs. upland) did have a significant influence on soil surface temperature and produced a variation in temperature 11 times greater than grazing intensities. Thermal heterogeneity did not differ among grazing treatments. Lower soil surface temperatures (associated with riparian areas) may provide a critical thermal refuge for many animals in arid and semiarid ecosystems on hot summer days, when air temperatures can exceed 37°C. Riparian zones, specifically riparian vegetation, are an important component in ecosystem management.     

Grassland Fire and Cattle Grazing Regulate Reptile and Amphibian Assembly Among Patches

Fire and grazing are common management schemes of grasslands globally and are potential drivers of reptilian and amphibian (herpetofauna) metacommunity dynamics. Few studies have assessed the impacts of fire and cattle grazing on herpetofauna assemblages in grasslands. A patch-burn grazing study at Osage Prairie, MO, USA in 2011–2012 created landscape patches with treatments of grazing, fire, and such legacies. Response variables were measured before and after the application of treatments, and I used robust-design occupancy modeling to estimate patch occupancy and detection rate within patches, and recolonization and extinction (i.e., dispersal) across patches. I conducted redundancy analysis and a permuted multivariate analysis of variance to determine if patch type and the associated environmental factors explained herpetofauna assemblage. Estimates for reptiles indicate that occupancy was seasonally constant in Control patches (ψ ~ 0.5), but declined to ψ ~ 0.15 in patches following the applications of fire and grazing. Local extinctions for reptiles were higher in patches with fire or light grazing (ε ~ 0.7) compared to the controls. For the riparian herpetofaunal community, patch type and grass height were important predictors of abundance; further, the turtles, lizards, snakes, and adult amphibians used different patch types. The aquatic amphibian community was predicted by watershed and in-stream characteristics, irrespective of fire or grazing. The varying responses from taxonomic groups demonstrate habitat partitioning across multiple patch types undergoing fire, cattle grazing, and legacy effects. Prairies will need an array of patch types to accommodate multiple herpetofauna species.     

Relationship Between Pastoralists’ Evaluation of Rangeland State and Vegetation Threshold Changes in Mongolian Rangelands

Applying the threshold concept to rangeland management is an important challenge in semi-arid and arid regions. Threshold recognition and prediction is necessary to enable local pastoralists to prevent the occurrence of an undesirable state that would result from unsustainable grazing pressure, but this requires a better understanding of the pastoralists’ perception of vegetation threshold changes. We estimated plant species cover in survey plots along grazing gradients in steppe and desert-steppe areas of Mongolia. We also conducted interviews with local pastoralists and asked them to evaluate whether the plots were suitable for grazing. Floristic composition changed nonlinearly along the grazing gradient in both the desert-steppe and steppe areas. Pastoralists observed the floristic composition changes along the grazing gradients, but their evaluations of grazing suitability did not always decrease along the grazing gradients, both of which included areas in a post-threshold state. These results indicated that local pastoralists and scientists may have different perceptions of vegetation states, even though both of groups used plant species and coverage as indicators in their evaluations. Therefore, in future studies of rangeland management, researchers and pastoralists should exchange their knowledge and perceptions to successfully apply the threshold concept to rangeland management.     

Simulated grazing responses on the proposed prairies National Park

The tallgrass prairie version of the ELM Grassland Model was used to evaluate the potential impact of establishing a tallgrass prairie National Park in the Flint Hills region of Kansas. This total ecosystem model simulates (a) the flow of water, heat, nitrogen, and phosphorus through the ecosystem and(b) the biomass dynamics of plants and consumers. It was specifically developed to study the effects of levels and types of herbivory, climatic variation, and fertilization upon grassland ecosystems. The model was used to simulate the impact of building up herds of bison, elk, antelope, and wolves on a tallgrass prairie. The results show that the grazing levels in the park should not be decreased below the prepark grazing levels (moderate grazing with cattle) and that the final grazing levels in the park could be maintained at a slightly higher level than the prepark grazing levels.