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Today East African pastoralists including Borana are increasingly engaged in livelihood diversification evolved over time as an adaptation strategy in the context of climate change and other stressors. This study was undertaken in Borana, southern Ethiopia, to understand women's involvement in livelihood diversification, as well as their gains and losses. The study employed household survey, focus group discussions, key informant interviews and field observations for data collection. Results show that traditional cattle-centered pastoralism has been transforming into more diversified livelihood activities such as crop production, animal trade, petty trade, poultry farming, and selling of firewood and charcoal. Although men dominate most of the pastoral livelihood diversification activities, this study shows women are also playing significant roles in petty trade, poultry farming, and selling of firewood, which increases women's workload and income and improves their decision-making power in the household. Moreover, the proactive role played by Borana women in diversification activities highlights women's initiatives in adaptation and challenges the dominant discourse that focuses on women's vulnerability to changes. Furthermore, a better understanding of the roles women play in diversification enables the use of their knowledge and expertise in designing well-informed policies and strategies.
Climate change may make semiarid grasslands increasingly prone to wildfire. We studied fire seasonality and growing season condition effects on a semiarid grassland in Southern Alberta, Canada. Plots were hand-torched in either fall or spring. Response variables estimated included plant composition and diversity, plant height, aboveground net primary production (ANPP), and forage nitrogen quality. The experiment was replicated over three consecutive growing seasons, and each replicate was monitored for 3 yr thereafter. Drought conditions occurred during two of the six growing seasons. Fall fires appeared to be hotter than spring fires based on a greater fuel mass (standing litter) and exposed the soil surface to a longer period without the benefit of standing litter over winter. Although this grassland is resilient to fire, compared with spring-burned grasslands, the species composition, ANPP, and leaf length of grasses of fall burned communities took a longer time to recover to preburn conditions. Our results suggest that spring-burned grasslands should not be grazed for 1 year post burn to allow time for recovery of ANPP and litter. However, given that ANPP of fall-burned communities also exhibited higher nitrogen concentration that may make the forage more palatable to livestock, and that these communities were more severely impacted, it seems prudent to delay their grazing for more than 1 year to prevent overgrazing. The negative impacts of fire on ANPP may be ameliorated with above-average precipitation in June, which may be forecast during an El Niño year.
Managing grasslands to sequester carbon is of global importance, but effects of grazing on soil organic carbon (SOC) stocks remain uncertain. We quantified effects of livestock grazing (grazed or not for 9–26 yr) and soil texture on SOC stocks (kg × m–2) of 20 sites in a temperate grassland. We also quantified the effects of livestock grazing on SOC concentration and bulk density. Percent sand explained a considerable amount of the variation in SOC stock (r2 = 0.45 to 0.59). In addition, SOC stocks were 12% less in areas rested from livestock grazing (i.e., not grazed) than annually grazed. Soil carbon concentrations were also 10% less in rested than grazed areas. Bulk density was 2% less in areas rested from grazing, but bulk density was greater at sites with longer periods of rest. We also detected a grazing treatment and rest duration interaction, indicating that bulk density differences between grazing treatments tended to be greater at sites with longer periods of rest. Compared with no grazing, moderate grazing tended to increase SOC stocks and concentrations. Although compaction (i.e., increase in bulk density) is generally regarded as an indicator of declining soil health, minor compaction may help reduce mineralization of SOC and ultimately increase SOC stocks. We discuss methodological improvements needed for a next generation of grazing land experiments to better resolve how best to manage livestock and sequester carbon.
Livestock guardian dogs (LGDs) are efficient at controlling predation upon livestock. LGDs create a safer landscape for livestock through accompaniment and the reduction of the abundance and distribution of wild carnivores. However, the effects of LGDs on livestock behavior, group dynamics, and use of space remain understudied. To understand LGDs' impact on sheep behavior and group dynamics, and using a natural experiment approach, we worked on two sheep farms that differed in the use of LGDs to control predation. We used the focal sampling technique to observe sheep behavior; in addition, we obtained information about group size and nearest neighbor distance. Nutritional quality and habitat selection were also assessed. For each individual, we calculated the proportion of time invested in behavioral categories (scanning, feeding, resting, and traveling), and categories between properties were contrasted with the nonparametric U-test, as well as features related to group dynamics, vegetation structure, and food quality. Furthermore, we investigated the effect of LGDs and other management and biological variables on sheep behavior and group properties. In close proximity to LGDs, sheep spent more time in scanning while time allocated to feeding decreased; however, feeding time did not change based on its presence. Moreover, LGDs' company led to the formation of larger sheep groups and individuals closer to each other. Sheep together with LGDs selected habitats with limited plant cover, which allows animals greater visibility. Lastly, we suggest that the ability of LGDs to maintain larger and more cohesive groups in open areas, as well as with more vigilant animals, could increase livestock responsiveness to predator presence, thus helping to reduce probability of predation on sheep and, in consequence, reducing the necessity of killing wild species in retaliation.
There are few side-by-side comparisons on how Kentucky bluegrass (Poa pratensis L.) invasion has affected plant diversity and carbon (C) and nitrogen (N) dynamics. Between 2013 and 2015, four plots (4.9 × 4.9 m) were annually located on a long-term (1916–2016), moderately stocked pasture at the Northern Great Plains Research Laboratory (USDA-ARS) near Mandan, North Dakota. All plots were located on loamy ecological with minimal microsite differences. Each site had areas that were visually observed to have the largest vegetative component dominated by either Kentucky bluegrass (KBG) or dominated by other species (CONT). Two 1/8 m2 quadrats were clipped by species, including detached plant material (litter), within each subplot between mid to late July 2013, 2014, and 2015. This period represents peak biomass production and offers the best opportunity to capture cool- and warm-season perennial species. In 2013, soil samples were taken at depths of 0–5, 5–10, and 10–20 cm within each plot and thatch samples were hand excavated after clipping. Carbon and N were determined on biomass, litter, thatch, and soil samples. KBG plots produced 28% more biomass annually than the CONT plots. In 2014 and 2015, species richness was 0.7–2.1 × greater in the CONT plots. Although N and C concentrations were similar between treatments for aboveground biomass, litter, and thatch when expressed on a g m–2 basis, N was 34% greater for aboveground biomass and 600% greater for litter in KBG plots. Soil organic C and total soil N at 0–5 cm were 26% and 22% greater in KBG plots, respectively. Our findings indicate that KBG plots had less diversity and greater aboveground and belowground N and C than CONT. More follow-on research is needed to understand how C and N stocks and dynamics influence Kentucky bluegrass invasion.
The quality and quantity of forage available to reproductive female ungulates during the summer can influence body condition and lactation, ultimately influencing herd production. The energetic costs of migration can influence individual fitness, thus understanding the mechanisms that drive some individuals in a partially migratory population to migrate, while others remain on winter range year-round, has important conservation and ecological implications. We examined differences in forage quality and quantity between migratory (n = 19) and resident (n = 17) summer home ranges for a population of mule deer (Odocoileus hemionus) in the John Day Basin of northeast Oregon. During 2018, we collected vegetation measurements three times throughout the summer (mid-May, mid-June, mid-July) to determine changes in dry matter digestibility (DMD; %) at three different phenological stages (emergent, mature, and cured) for three forage classes (grass, shrub, forbs). On the second visit, at the peak of the growing season, we collected biomass and cover data to determine differences in forage quantity for each forage class between the migratory and resident summer ranges. In mid-June 2019, we revisited a subsample of sites (migratory [n = 5]; resident [n = 5]) to estimate interannual variation. Migratory deer had access to overall higher quality forage at higher-elevation summer ranges. Forbs had the highest forage quality on both summer ranges. Forage quality declined across the entire study area as moisture declined and vegetation senesced. Shrub forage quality was higher (DMD = 54.1%) on resident ranges than migratory ranges (49.7%; P = 0.001). Grasses had higher biomass (26.1 Mg/ha) and cover (50.1 %) than forbs (19.2 Mg/ha; 34.7% cover) or shrubs (20.6 Mg/ha; 6.7% cover) across the entire summer range. Overall, migratory deer had access to higher-quality forage throughout the summer, yet resident deer had access to higher-quality shrub browse. This trade-off in forage availability may partially explain the persistence of a partially migratory population as a bet-hedging strategy on a landscape where low moisture availability and episodic drought and disturbance create variable foraging conditions.
Rangelands provide numerous ecosystem services, including forage for livestock grazing. Effective grazing management requires measuring forage availability, which influences the level of grazing that can be sustained while maintaining healthy ecological conditions. However, spatiotemporal variability makes such determinations of forage quantity difficult, potentially hindering optimal management. These determinations are especially difficult across large, remote areas. To address this, we developed an approach using data from a one-time sampling of vegetation throughout the Uintah and Ouray Reservation in northeast Utah. By associating these data in a random forest model with environmental and climatic covariates that vary annually, we produced yearly predictions of forage availability on a pixel-by-pixel basis for the Reservation and surroundings from 1984 to 2018. This method addresses and quantifies the spatiotemporal variability of available forage. The model confirms that forage availability is highly variable throughout the area. On average, forage availability in Reservation management units declined as much as 32% below median availability in some years and increased 33% above median availability in others. Moreover, some management units experienced large increases in favorable years but less significant declines in unfavorable years, while the opposite was true in others. In comparison to determining a single “typical” forage availability of management units, recognizing this inherent variability and how it differs between units provides a fuller picture of the range of possible forage availability. This can improve grazing management by revealing how forage quantities vary from year to year and may help avoid forage overutilization during unfavorable years such as drought. The model can continue to be used into the future to monitor vegetation trends, though with ongoing climate and vegetation changes periodic recalibration may be necessary. In addition, the modeling method may be applicable to other similar study systems.
Many rangelands worldwide are threatened by human population growth, so there is an urgent need for understanding how we can preserve functional diversity across these systems. The conservation and restoration of mammalian carnivores (order Carnivora) is critical because they impart important trophic cascading effects. Land use practice on rangelands may determine carnivore distributions and abundances; thus, to effectively facilitate coexistence between carnivores and humans, it is essential to understand carnivore community functioning in human-dominated landscapes. We conducted a camera trapping survey on multiple-use rangeland in north-central Namibia to investigate the spatial ecology of free-ranging carnivores in a farming system that comprises both livestock farming activities and wildlife-based land uses. We hypothesized that carnivore diversity and occupancy would be determined by farm type and predicted the associations of carnivore distributions with covariates related to resource availability, intraguild interactions, and anthropogenic influence. We considered single-season occupancy models and hypothesized that in this semiarid study system, seasonality had profound effects on the spatial ecology of carnivores. Our results show that Namibian multiple-use rangeland supported a diverse carnivore guild. Carnivore diversity and occupancy were generally similar across farm types, suggesting that the carnivore community assemblage in our study area was homogeneous. Local-scale variation in land use practices did not limit carnivore distributions, which could be key to maintaining ecological integrity of rangelands. The effect of seasonality suggested that carnivore space use on Namibian rangelands was influenced by availability of dry season resources. In addition, carnivores were dependent on natural resources, showed complex interactions with intraguild members, and had seasonally contrasting associations with anthropogenic activities. Namibian multiple-use rangelands may function as viable socioecological landscapes and could act as an important link between core conservation areas.
Estimating plant biomass in rangeland ecosystems is essential to understanding carbon cycling, impacts on natural resources, and ecological functioning or structure—all of which inform sustainable land management. However, biomass estimation has been relatively understudied for the sagebrush steppe of North America, one of the continent's most widespread ecosystems. As a nondestructive alternative to direct biomass measurements, allometric models may be used to estimate aboveground plant biomass using predictor variables once models are developed. With this as our aim, we developed species-specific and multispecies models for eight common bunchgrass species in Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) plant communities. As codominant perennials, these bunchgrass species provide much of the forage for large herbivores while contributing to soil stability and carbon storage. To develop allometric models for these bunchgrass species, we used individual height, basal diameter, and tiller count as predictor variables. On average, multiple-predictor models (RMSE CV = 61%) were more effective (i.e., exhibited more agreement between predicted and actual biomass) than single-predictor models (RMSE CV = 79%). Power models (RMSE CV = 66%) were slightly more effective than exponential models (RMSE CV = 72%). Applying models to each species demonstrated that the effectiveness of multispecies (RMSE CV = 65%) versus species-specific (RMSE CV = 67%) models largely depended on the species being modeled. Combining our models with plant density resulted in an area-based biomass estimate range (2.3–26.7 g/m2) that generally agreed with previous studies (0.2–19 g/m2). It is our hope that the allometric models developed in this study will be tested on various locations and ultimately inform rangeland management throughout the big sagebrush region.
Arbuscular mycorrhizal fungi (AMF) are drivers of plant communities as they influence plant competition by increasing plants' root absorptive surface. As such, AMF could be an important tool for ecological restoration. However, a lack of research using AMF in sagebrush steppe communities implies a need for more assessments of its efficacy. Here, we assessed the ability of a commercial inoculum to colonize and influence growth of three native Artemisia spp. (sagebrush) shrubs and the exotic Taeniatherum caput-medusae (medusahead). We expected to increase colonization and biomass production with the addition of the inoculum. Before testing the inoculum, its viability was examined using Trifolium incarnatum (crimson clover) in autoclaved soil. Next, a factorial greenhouse experiment was conducted to evaluate the target species when grown in live or autoclaved field soil from a disturbed (early seral) site. Inoculation resulted in an average root colonization of 24.82% ± 4.86% for T. incarnatum but failed to colonize any of the sagebrush steppe species in autoclaved soil and had little to no influence on colonization in live soil. All sagebrush steppe species were colonized by AMF in live soil, and biomass production averaged 889 mg, 530 mg, 323 mg, and 1 852 mg, respectively; however, average biomass for all species was greater when grown in autoclaved soils (1 620 mg, 706 mg, 371 mg, and 3 902 mg, respectively). Our results reveal differential effects of a commercial AMF inoculum on root colonization of Artemisia spp. and T. incarnatum and highlight the need to assess the efficacy of AMF inoculum before field application.
Grazing and fire are both independently important drivers of plant community dynamics; however, their interactive effects may be even more influential. Little is known about prefire grazing effects on postfire plant community dynamics. We investigated the effects of dormant-season, moderate prefire grazing by cattle on postfire plant community response in the imperiled Artemisia (sagebrush) steppe. Treatments were moderately grazed or not grazed by cattle for 5 yr before fire. The first yr post fire, shrub density was 4 × greater in grazed areas, demonstrating fire-induced mortality was reduced with grazing. This further suggested that grazing reduced fire severity and postfire large bunchgrass biomass was greater in grazed compared with ungrazed areas. Biomass and abundance of the exotic annual grass, Bromus tectorum L., were substantially greater and plant diversity was lower in ungrazed compared with grazed areas post fire. Five years post fire, perennial herbaceous vegetation still dominated prefire-grazed areas, but ungrazed areas were dominated by B. tectorum, suggesting that a novel ecosystem state had developed. Substantial increases in B. tectorum are concerning because it prevents recruitment of native perennial plants and increases fire frequency, which would further decrease diversity and reinforce an exotic annual-dominated state. Lower diversity in ungrazed areas post fire is concerning because diversity can be important for plant community stability. The importance of livestock as ecological engineers through their influence on fire has largely been overlooked but is clearly substantial and needs to be integrated into conservation and management plans.
In the North American Northern Great Plains, Kentucky bluegrass (Poa pratensis L.) and smooth bromegrass (Bromus inermis Leyss. subsp. inermis) pose a serious threat to native grassland integrity and function. This study's objectives were to 1) determine drought resistance of non-native grassland and invaded-native tallgrass prairie during 1 and 2 yr of drought and 2) determine drought resilience of nonnative grassland and invaded-native tallgrass prairie after 1 yr of drought and 1 yr of recovery with 100% of average precipitation. Three rainout shelters, 3.6 m x 4 m, were installed on non-native and invaded-native grassland in eastern South Dakota to simulate drought conditions by excluding ambient rainfall. The shelter system was constructed on a track whereby the shelter automatically moved over the experimental plots when it rained and moved away from the plots when it stopped raining. Weekly watering treatments consisted of ambient, 75%, 100%, 125%, and 250% of the 30-yr average in 2013 and 2014 (Experiment I). Also, in 2014 a second set of the 75%, 100%, and 125% watering treatments were watered to 100% of the 30-yr average (Experiment II). Drought reduced biomass production in both non-native and invaded-native grassland sites. When plots were watered to 100% of the 30-yr average, the non-native site had similar amount of biomass compared with the drought year, but the invaded-native site had lower biomass. This response provides more evidence regarding the aggressive nature of these two introduced cool-season grasses and a mechanism to explain their continual dominance and expansion in this region.
Fire is widely used by farmers in Brazil during the winter, or the dry season, to remove accumulated dead pasture biomass. These practices have substantial impacts on vegetation, soil nutrients and carbon emissions. However, they are rarely represented within process-based fire models embedded within Dynamic Global Vegetation Models (DGVM). We developed an algorithm named Chalumeau to estimate the expected burning dates from daily precipitation or temperature depending on the seasonality type. By coupling with a fire module from a DGVM, Chalumeau enables the ignition of fire as an essential part of modelling fire practices. The burning dates are evaluated by comparing against observed fire dates on pasture. From these estimated dates, we extract the timing strategies of ranchers, which vary regionally within Brazil. This study confirms that climatic conditions are the main trigger for farmers decisions to set fire and shows the different burning strategies across Brazil.
Studying the effects of trampling at different stages on plant reproduction is necessary to provide the basis for grassland management. However, the changes in forage growth characteristics are still unclear under the action of livestock trampling from soil thawing to regreening stage of alpine meadows.
We studied the changes of growth, reproduction, and storage characteristics of Kobresia humilis in the alpine meadow of Tianzhu, Gansu Province, after 2 yr of simulated Tibetan sheep and yak trampling at five periods (prophase, initial, and middle period of thawing, initial regreening, and regreening period).
Trampling period had the highest influence on K. humilis phenotypic traits, followed by livestock species. Considering the same trampling period, the negative effects of Tibetan sheep trampling on the sexual reproduction, different modular biomass, and root growth of K. humilis were lower than those of yak trampling. Sexual reproduction effort and storage growth effort were higher in Tibetan sheep trampling conditions, and vegetative reproductive effort was lower in sheep compared with yak trampling treatment conditions.
There was a trade-off of resource allocation between K. humilis reproductive organs and storage organs. For the average of each indicator under different combination treatments, the vegetative reproductive effort was 11.1 times that of sexual reproduction effort. The comprehensive evaluation of K. humilis phenotypic traits showed that the trampling treatments could be divided into excellent (prophase period of thawing), good (middle period of thawing), general (initial period of thawing), and inferior (initial regreening to regreening period) grades of Tibetan sheep and yak trampling.
We suggest that the actual grazing process in the cold-season pastures of this alpine meadow should be fully used at the prophase of soil thawing, implement rest-grazing for grassland and confinement from initial period of soil thawing to the forage regreening period, and appropriately increase the proportion of Tibetan sheep and reduce the number of yaks to avoid the high-intensity trampling of grassland. This will not only make optimum use of the limited grassland resources but also promote their recuperation.
Mob-grazing involves maintaining high densities of livestock for short periods so that most plants are either eaten or trampled, followed by long rest periods. This practice has been proposed as a mechanism to increase soil carbon (C) storage and range quality. However, mob-grazing has not universally achieved these objectives, possibly because many factors influence the effects of grazing on soil C dynamics and vegetation. This study examines factors that may mediate grazing impacts on soil C by comparing plant cover and the seasonal dynamics of roots, soil variables, and mycorrhizal fungal hyphae in experimental plots treated with traditional grazing, annual mob-grazing or no grazing for 18 yr. Root and soil variables were measured directly underneath a C4 grass, a C3 grass, and a forb up to 5 × during a 13-mo period. Mob-grazing did not influence total soil C, but it significantly increased soil organic matter (SOM), fine particulate organic matter, and nitrogen-15 (δ15N). Furthermore, mob-grazing increased soil compaction, decreased soil aggregate stability, decreased soil moisture, and tended to increase the abundance of two invasive plant species: Salsola tragus and Bromus tectorum. Soil compaction, soil aggregate stability, root biomass, particulate organic matter, and percent soil C and N varied significantly across seasons and among plant species. The density of mycorrhizal fungal hyphae varied with season but not with grazing treatment. A significant grazing by date interaction in root biomass and soil carbon-13 (δ13C) suggests that root dieback and inputs of pulverized plant material with a higher δ13C signature could be the source of higher SOM in mob-grazed plots. Compared with ungrazed plots, traditionally grazed plots had higher SOM without the adverse impacts on vegetation and soil properties observed in the mob-grazed plots. No single management strategy is universally beneficial. Range managers should carefully weigh the pros and cons of mob-grazing because, although it can increase SOM in surface soils, it may also negatively impact soil structure and composition of vegetation.
Greater sage-grouse (Centrocercus urophasianus, hereafter, sage-grouse) have experienced habitat loss from expansion of juniper (Juniperus spp.) woodlands into sagebrush steppe. Sage-grouse avoid high levels of juniper cover (> 10% cover) but can vary in response to cover > 0–10%. Selection patterns by hens may be affected by differences in resource needs or predation risk between brooding (i.e., hens with chicks) and nonbrooding hens (i.e., hens without chicks). We investigated whether reproductive status influenced habitat selection at multiple spatial scales among hens in a landscape undergoing juniper expansion. We conducted our study during the 2017–2018 breeding seasons in southwestern Idaho. We collected habitat data at broad spatial extents (hereafter, macroscales) using remotely sensed layers and at a fine spatial extent (hereafter, microscale) with field-based surveys. We collected data at used and available locations for 11 brooding and 19 nonbrooding hens at macroscales (n = 2 059 locations) and microscales (n = 181 locations). At the macroscales, both reproductive groups avoided cover class II (> 10–20% juniper cover) and III (> 20% juniper cover) but nonbrooding hens were 2.8 × more likely to select cover class I (> 0–10% juniper cover) than brooding hens. In addition, nonbrooding hens selected wetlands dominated by woody vegetation (e.g., willows), whereas brooding hens selected wetlands dominated by herbaceous vegetation. At the microscale, brooding hens were 22.1 × more likely to select taller nonsagebrush shrubs than nonbrooding hens. Our results support our prediction that nonbrooding hens were more likely to select cover class I juniper than brooding hens. Our results help inform more targeted treatment whereby removal of juniper around wetlands and mesic habitats with taller nonsagebrush shrubs may be the most beneficial because increasing the availability of these habitats could positively influence survival of chicks and adults.
Sand shinnery oak (Quercus havardii) shrublands are estimated to have once occupied 5–7 million ha across the southwestern United States. As a result of herbicide and plowing, this endemic vegetation community has been significantly reduced in extent. Further, sand shinnery oak shrublands were historically maintained by relatively frequent fires, but recent fire suppression has resulted in substantial changes in plant community composition and structure where this vegetation type remains. Few studies have been conducted to determine wildlife species composition and richness in remaining sand shinnery oak shrublands and how management practices, such as fire, may influence species occurrence. In this study, we conducted breeding bird surveys in an intact sand shinnery oak shrubland managed with prescribed fire in western Oklahoma to describe the breeding bird assemblage and evaluate the effects of prescribed fire on species abundance. We found the breeding bird community varied along a gradient of sites with high tree/tall shrub density to more open sites dominated by grasses and sand shinnery oak. Bird species richness increased with higher tree/tall shrub densities and declined with greater cover of grasses, shrubs, and bare ground. The 10 most common bird species displayed a range of responses to prescribed fire. Species such as northern bobwhite (Colinus virginianus) and field sparrow (Spizella pusilla) had their greatest relative abundance in recently burned patches, and species such as painted bunting (Passerina ciris) and Bewick's wren (Thryomanes bewickii) were most abundant in patches that were > 36 mo post fire, with many of the remaining species having peak abundance in intermediate times since fire. Our findings show prescribed fire can be used to create a diversity of vegetation structure that provides habitat for multiple shrubland and grassland bird species. However, factors such as tree density and precipitation may influence the response of bird species to prescribed fire.
Reducing grass standing crop by grazing may increase forbs and benefit wildlife that depend on forbs. However, precipitation and soil texture also strongly influence forb standing crop. We determined if standing crop of forbs selected by white-tailed deer (Odocoileus virginianus Zimm.) is more strongly influenced by grazing or precipitation. Ungulates typically graze in patches with greater standing crop than the surrounding vegetation. Our second objective was to determine if predicted relationships of forb standing crop with grazing, precipitation, and percent sand were similar with less productive sites included or excluded from models. We estimated standing crop of grasses and forbs in 50 paired grazing exclosures and grazed plots on each of six 2 500-ha study sites. Standing crop of forbs selected by white-tailed deer (selected forbs) was strongly related to precipitation and percent sand but not estimated percent use of grasses. For our second objective, we examined grazing effects on forbs by removing pairs of exclosures and grazed plots from the data where grass standing crop in nongrazed exclosures exceeded the average standing crop of grass after grazing. Percent use of grasses did not influence selected forb standing crop when we included only productive patches. For overall forb standing crop in productive patches, percent use of grasses and percent sand interacted. Forbs declined with increasing percent use of grasses in less sandy soils and increased with percent use of grasses in sandy soils. Grazing is not useful to increase forbs selected by white-tailed deer in our study sites because standing crop of selected forbs is more strongly dependent on precipitation and soil texture than on grazing. Grazing did influence forb standing crop in productive areas, which suggests accounting for grazing effects in productive versus less productive areas of the landscape provides insight into herbivore-vegetation relationships.
Salt cedar (Tamarix spp. L), is found across Texas and the western United States, primarily near riparian areas. Introduced in the 1800s as an ornamental plant, salt cedar escaped domestic gardens, invading native rangelands. Mechanical and chemical control options for salt cedar are available, but effective control can be difficult and cost prohibitive. Sheep and goats will readily consume salt cedar after exposure at weaning, and goats readily consume the plant when released on rangelands. Unfortunately, sheep and goats are not a viable option in many areas due to predation or lack of appropriate fencing. The objectives of this study were to determine if cattle would consume salt cedar at a similar level (body weight basis) as sheep and goats and to determine if preconditioning improved acceptance of salt cedar by cattle. Angus-Hereford cross heifers (n = 15), Rambouillet lambs (n = 15), and Boer-Spanish cross kids (n = 15) were placed in individual pens for 21 d and fed salt cedar leaves and tender stems daily. For the first 21 d, eight head from each species were fed a basal diet and salt cedar while 7 head only received the basal diet. The amount of salt cedar in the diet was increased from 5% of the diet to 10% of the diet after 7 d of feeding and fed until d 21. From d 22 to 28 both naïve and familiar animals were fed salt cedar daily. All animals readily increased intake of salt cedar. By d 7, cattle, sheep, and goats consumed the plant, but intake varied daily for cattle and sheep. After the first 7 d, goats consistently ate more (P < 0.05) salt cedar than cattle or sheep. While goats may consume more salt cedar, cattle may be a viable option to reduce salt cedar cover when goats are not a viable option.
The exotic annual grass medusahead (Taeniatherum caput-medusae [L.] Nevski) has invaded millions of hectares in the western United States. The herbicide aminopyralid is an emerging tool for controlling medusahead. Aminopyralid reduces viability of grass seeds when applied just before seed production. In annual grasslands, desirable forage grasses generally begin seed production before medusahead, and applying aminopyralid when medusahead is still mostly vegetative but forage grasses have begun producing seed allows medusahead to be targeted somewhat selectively. In recent experiments, this approach reduced medusahead viability and cover to near zero and increased forage grasses. These experiments occurred in small plots, and results may differ in pastures if grazing or environmental heterogeneity causes plant stages to vary. Moreover, the results may prove highly sensitive to application timing. To address these information gaps, we factorially combined grazing and aminopyralid treatments in pastures and varied application timings in small plots. In pastures, aminopyralid reduced medusahead cover from about 45% to 20% one yr and from 60% to 20% another year. These reductions are smaller than in past research, but this doesn't seem attributed to the larger treatment area because reductions were similar in pastures and small plots treated the same time. Despite smaller reductions in medusahead cover, forage grasses increased as much or more than previously, perhaps because aminopyralid previously more sharply reduced forage grass seed viability. Seed viability did not vary with grazing, indicating grazing can occur during treatment, because aminopyralid does not have grazing restrictions. Careful application timing is critical: Just 12 d separated the least (jointing and boot stages) and most (boot to early heading) effective timings for controlling medusahead. A low rate of aminopyralid (22% of maximum labeled rate) is needed to reduce medusahead seed production, and the low cost of the low rate should encourage repeated applications when necessary.
Reclamation of surface disturbances on grasslands is an important management issue. This research examined how cattle grazing and revegetation treatments influenced vegetation development on mixed-prairie well sites. Three seed mix treatments, dominant wheatgrass (a Triticeae tribe) (four species providing 95% wheatgrass seed in the seed mix), nondominant wheatgrass (five species with 80% nonwheatgrasses in the seed mix), and diverse (22 grass and forb species), plus a natural recovery (unseeded) treatment, with and without cattle grazing, were compared with undisturbed (control) prairie for soil seedbank, vegetation composition, ground cover, and biomass. The nondominant wheatgrass seed mix resulted in communities dominated by wheatgrass species, whereas natural recovery was dominated by early and midseral species. Seeding yielded greater aboveground biomass with < 20% bare ground; natural recovery biomass was slightly less with greater bare ground (grazed 45%, ungrazed 23%). Cattle grazing reduced cover of northern wheatgrass (Elymus lanceolatus [Scribn. & J.G.Sm.] Gould) in seeded treatments. Species richness and diversity were greater with natural recovery than with seeding and in undisturbed prairie. Multivariate tests showed that plant community composition in undisturbed prairie and natural recovery differed from seeded treatments; natural recovery was dominated by early to mid-successional species. The short-term patterns of change in different vegetation parameters suggest that irrespective of grazing, natural recovery and seeding with a diverse native seed mix could be effective approaches for mixed-prairie reclamation.
Marissa A. Ahlering, Clare Kazanski, Patrick E. Lendrum, Pablo Borrelli, William Burnidge, Lexi Clark, Chad Ellis, Kirk Gadzia, Jonathan Gelbard, Sasha Gennet, Jeff Goodwin, Jeffrey E. Herrick, Emily Kachergis, Corrine Knapp, Nancy Labbe, Kristie Maczko, Elizabeth Porzig, David Rizzo, Sheri Spiegal, Christopher Wilson
While increasing numbers of ranchers are striving to demonstrate sustainable ranching operations geared toward a healthy landscape, companies are seeking to advance sustainability along beef supply chains and consumers are making more environmentally oriented purchasing choices. Yet there is a need for greater clarity on which indicators are most effective for assessing and monitoring sustainable management and continuous improvement of ranching operations. Our objective was to synthesize existing guidance on monitoring and assessing ranch-scale sustainability in the United States and to identify core ecological, social, and economic indicators that could identify well-managed ranching, support adaptive management, and demonstrate producers' sustainability and continuous improvement to retailers and consumers. We evaluated 21 range and pastureland assessments from nongovernmental organizations, agencies, and academics that totaled 180 indicators. From this, we selected 20 commonly used “core” indicators (12 ecological and 8 socioeconomic). We identified indicators that are designed to detect change over time for management practices, common among many approaches, and/or critical indicators for outcomes of common interest to producers, companies, and consumers. The synthesis of indicators across many guidance documents offers insight into what a diverse set of range professionals and institutions see as critical to demonstrate and track ranch-level sustainability, and producers, consumers, and companies may find a subset of these indicators to be relevant for their operation and region, values, and/or company sustainability goals. The synthesis also highlights the need for more integration and agreement on socioeconomic indicators of ranch sustainability. We acknowledge that socioeconomic indicators are context dependent and discuss the pitfalls of not integrating them into ranch assessments. Finally, we identified four issues to consider in operationalizing widespread use of common indicators: 1) who bears the cost, 2) agreement on simple and robust standardized protocols, 3) developing region-specific thresholds, and 4) issues of data privacy and sharing agreements for data use.
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